Homebrew PCBs

A previous poster made the following comment:
    I did 'em myself using Radio Shack FeCl³.  I tried Ammonium
    Persulfate once, but NO WAY at home, ever again!  Whew!

I had used messy ferric chloride when I made some hobby PCBs about 25 
years ago, but I have seen other less-staining etchants are now 
available, such as ammonium persulphate and sodium persulphate.

What are most people using at home, and what are the pros and 
cons of the various etchants?  Cost?  Shelf life?  Ease of use?  
Safety?  Cleanliness?  Availability?

WT
Winnipeg, Canada

First of all, thanks for the replies concerning the various reasons you are
all constructing boards.  I’m sure I’ll find the ongoing discussions
interesting in this group.

 

I suppose I’ll offer something to the group by making a submission on this
subject of Etchants.  Since I don’t know what everyone is using for
etchants at home (and I’m not doing any type of this work at home myself),
I can offer what I know from the industry.  My experience has been that the
three major etchant types used are:

 

1)      Ammoniacal (Ammonium chloride)

2)      Cupric Chloride

3)      Ferric Chloride

 

Typically I find Ammonium Chloride and Cupric Chloride used for producing
circuit boards, and Ferric Chloride used in the chemical milling industry.  

 

For home use, I would think that either Cupric Chloride or Ferric Chloride
would be preferred.  Ammonium Chloride (as someone pointed out earlier)
produces quite an ammonia smell, which is much worse when the solution is
heated.  However, if you are using tin / tin lead as an etch resist, then
Ammonical Chloride is “typically” required (this may not be the case in
home etching scenarios) since other etchants will etch away tin / tin lead
resist.

 

Cupric Chloride and Ferric Chloride share a few similarities.  In the old
days, both were rejuvenated using the oxidizer “chlorine gas”, then later
people started using Hydrogen Peroxide, but now a-days people use Sodium
Chlorate (salt water, for example).  This oxidizer can easily be made at
home by mixing a clean rock salt with water, allowing the water to absorb
as much salt as possible.  Then the salt water (brine) is added to the
etchant to rejuvenate it.  Note… this rejuvenation process is only for
Cupric Chloride or Ferric Chloride… not Ammonium Chloride.  There is a
great deal of technical detail that can be discussed when adding an
oxidizer to the etchant (such as monitoring the oxidation reduction
potential), but I’m not sure if that is needed for this group.  Let me
know if you would like that information and I’ll put something together,
or I’m sure this information could easily be found on the Internet.  

 

Cupric Chloride and Ferric Chloride also need a certain amount of
Hydrochloric Acid, another item fairly easily obtained (Muratic Acid can be
used, and it is much easier to obtain).  And of course, both Cupric and
Ferric will need a certain amount of Copper and Ferric Iron ions in
solution for the whole etching process to occur.  Again, much detail is
available for these two components (monitoring the Hcl level with methods
such as titration or electronically, and monitoring the specific gravity of
copper / Iron levels… very easily done with a hydrometer).

 

Of the three, the Ferric Chloride is probably the easiest to dispose.  I
have been told those years ago, some cities encouraged manufacturing plants
using Ferric Chloride to dump the solution down the drain when they wanted
to dispose of it.  Apparently, it helped keep the city pipes clean!  NOTE:
(here’s my disclaimer) I am in no way suggesting that you do this with
your ferric chloride etchant.

 

I’ll leave it there for now.  I’ll just add that I remember many years
ago when I took an electronics class, I used Ferric Chloride as my etchant
(just poured it out of a gallon jug and “swished” my board around until
the exposed copper was gone.  Worked pretty well for a single sided, single
layer board, but I also remember that board had line widths and spaces of
about a half inch.  

 

Thanks for letting me contribute.  Take care.

Marty

-----Original Message-----
From: wturchyn [mailto:wturchyn@...] 
Sent: Thursday, May 22, 2003 10:18 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Etchant options?

 

A previous poster made the following comment:
    I did 'em myself using Radio Shack FeCl³.  I tried Ammonium
    Persulfate once, but NO WAY at home, ever again!  Whew!

I had used messy ferric chloride when I made some hobby PCBs about 25 
years ago, but I have seen other less-staining etchants are now 
available, such as ammonium persulphate and sodium persulphate.

What are most people using at home, and what are the pros and 
cons of the various etchants?  Cost?  Shelf life?  Ease of use?  
Safety?  Cleanliness?  Availability?

WT
Winnipeg, Canada








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[Non-text portions of this message have been removed]

there is also the possibility to use either hcl or sulphuric acid in combination with hydrogen peroxyde.
the hcl H2O2 method is very related to "air oxygen regenerated cupric cloride" but much faster and a bit 
different i think.
the sulphuric acid method seems to be good when using metal film resist and also stainless tanks are 
fine. (this seems to be a more selective etchant).

with using h2o2 and hcl you can get etching to happen fine in 30 seconds (i did around 10 some times).
without much stirring etc, simply put in in jar.

i belive it is faster than (air) cucl etching because also the conversion from plain copper and hcl to 
CuCl2 is utilised for etching and not only CuCl2 enriched to Cu2Cl2. (hope i got this right).
this is only a guess by me. also regeneration is done instantly while etching.

i also did messy fe3cl, but don't like it.

regards
stefan


22.05.2003 17:23:22, "Marty Grove" <MartyGrove@...> wrote:

>First of all, thanks for the replies concerning the various reasons you are
>all constructing boards.  I\ufffd\ufffdm sure I\ufffd\ufffdll find the ongoing discussions
>interesting in this group.
>
> 
>
>I suppose I\ufffd\ufffdll offer something to the group by making a submission on this
>subject of Etchants.  Since I don\ufffd\ufffdt know what everyone is using for
>etchants at home (and I\ufffd\ufffdm not doing any type of this work at home myself),
>I can offer what I know from the industry.  My experience has been that the
>three major etchant types used are:
>
> 
>
>1)      Ammoniacal (Ammonium chloride)
>
>2)      Cupric Chloride
>
>3)      Ferric Chloride
>
> 
>
>Typically I find Ammonium Chloride and Cupric Chloride used for producing
>circuit boards, and Ferric Chloride used in the chemical milling industry.  
>
> 
>
>For home use, I would think that either Cupric Chloride or Ferric Chloride
>would be preferred.  Ammonium Chloride (as someone pointed out earlier)
>produces quite an ammonia smell, which is much worse when the solution is
>heated.  However, if you are using tin / tin lead as an etch resist, then
>Ammonical Chloride is \ufffd\ufffdtypically\ufffd\ufffd required (this may not be the case in
>home etching scenarios) since other etchants will etch away tin / tin lead
>resist.
>
> 
>
>Cupric Chloride and Ferric Chloride share a few similarities.  In the old
>days, both were rejuvenated using the oxidizer \ufffd\ufffdchlorine gas\ufffd\ufffd, then later
>people started using Hydrogen Peroxide, but now a-days people use Sodium
>Chlorate (salt water, for example).  This oxidizer can easily be made at
>home by mixing a clean rock salt with water, allowing the water to absorb
>as much salt as possible.  Then the salt water (brine) is added to the
>etchant to rejuvenate it.  Note\ufffd\ufffd this rejuvenation process is only for
>Cupric Chloride or Ferric Chloride\ufffd\ufffd not Ammonium Chloride.  There is a
>great deal of technical detail that can be discussed when adding an
>oxidizer to the etchant (such as monitoring the oxidation reduction
>potential), but I\ufffd\ufffdm not sure if that is needed for this group.  Let me
>know if you would like that information and I\ufffd\ufffdll put something together,
>or I\ufffd\ufffdm sure this information could easily be found on the Internet.  
>
> 
>
>Cupric Chloride and Ferric Chloride also need a certain amount of
>Hydrochloric Acid, another item fairly easily obtained (Muratic Acid can be
>used, and it is much easier to obtain).  And of course, both Cupric and
>Ferric will need a certain amount of Copper and Ferric Iron ions in
>solution for the whole etching process to occur.  Again, much detail is
>available for these two components (monitoring the Hcl level with methods
>such as titration or electronically, and monitoring the specific gravity of
>copper / Iron levels\ufffd\ufffd very easily done with a hydrometer).
>
> 
>
>Of the three, the Ferric Chloride is probably the easiest to dispose.  I
>have been told those years ago, some cities encouraged manufacturing plants
>using Ferric Chloride to dump the solution down the drain when they wanted
>to dispose of it.  Apparently, it helped keep the city pipes clean!  NOTE:
>(here\ufffd\ufffds my disclaimer) I am in no way suggesting that you do this with
>your ferric chloride etchant.
>
> 
>
>I\ufffd\ufffdll leave it there for now.  I\ufffd\ufffdll just add that I remember many years
>ago when I took an electronics class, I used Ferric Chloride as my etchant
>(just poured it out of a gallon jug and \ufffd\ufffdswished\ufffd\ufffd my board around until
>the exposed copper was gone.  Worked pretty well for a single sided, single
>layer board, but I also remember that board had line widths and spaces of
>about a half inch.  
>
> 
>
>Thanks for letting me contribute.  Take care.
>
>Marty
>
> 
>
> 
>
> 
>
> 
>
> 
>
>-----Original Message-----
>From: wturchyn [mailto:wturchyn@...] 
>Sent: Thursday, May 22, 2003 10:18 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Etchant options?
>
> 
>
>A previous poster made the following comment:
>    I did 'em myself using Radio Shack FeCl\ufffd\ufffd.  I tried Ammonium
>    Persulfate once, but NO WAY at home, ever again!  Whew!
>
>I had used messy ferric chloride when I made some hobby PCBs about 25 
>years ago, but I have seen other less-staining etchants are now 
>available, such as ammonium persulphate and sodium persulphate.
>
>What are most people using at home, and what are the pros and 
>cons of the various etchants?  Cost?  Shelf life?  Ease of use?  
>Safety?  Cleanliness?  Availability?
>
>WT
>Winnipeg, Canada
>
>
>
>
>
>
>
>
>Yahoo! Groups Sponsor
>
>
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><http://rd.yahoo.com/M=249982.3179269.4495679.1261774/D=egroupweb/S=17050832
>91:HM/A=1524963/R=0/*http:/hits.411web.com/cgi-
>bin/autoredir?camp=556&lineid=3179269\ufffd\ufffd=egroupweb&pos=HM> 
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>l/S=:HM/A=1524963/rand=712236907> 
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><http://docs.yahoo.com/info/terms/>  Terms of Service. 
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>[Non-text portions of this message have been removed]
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>Be sure to visit the group home and check for new Bookmarks and files:
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>
>
>

Hi Marty,

Interesting info.  Thanks.

Would you have any info relating to how clean the final etch is, and what 
minimum traces can be obtained by each of the options you mentioned.  I've 
traditionally used FeCl, but just picked up some Ammonium Persulphate (MG 
Brand) but haven't tried it yet.  Also, the ammonium fumes may be a problem 
so I'm not trying to get as much info as possible before I actually try it.

Cheers,
-Neil.


On Thursday 22 May 2003 10:23, Marty Grove scribbled:
> <lots o' stuff>

i think all processes are capable of providing nearly the same results if used properly.
the one thing is the resist, it must be suited for the etchant.
the second, underetching under the resist, can be prevented if the process is used the right way.
i think if all is right (aeriation if needed, stirring, heating) and all is set up to result in a even 
etch over the whole board there is nearly no under-etching.

i think the most of the listed processes are also used in professional setups(some more often, some 
less). 
therefore they all should be suitable to provide perfect results.

i think for setting up a etch it is important to consider the following:
availability of the chemicals.
disposal regulations / possibilities.
required speed.
available room.
time you want to invest, money you want to invest.
very important: number of pcbs per time unit you want.
ability to build etching compartments (more complicated with spraying/aeration)

you can use methods which need virtually no preparation/maintainance but also need more time/money when 
actually making a pcb. but in methods like cucl you have to prepare the etch quite a time before and 
also you need time for regeneration etc.


if you really want to make pcbs in your garage you have to read descriptions for all methods.
you have to look at your stores what you can get easily. only then you can decide.
you will soon find arguments against the one or other method.


regards
st


22.05.2003 18:20:36, Neil <cobra_neil@...> wrote:

>Hi Marty,
>
>Interesting info.  Thanks.
>
>Would you have any info relating to how clean the final etch is, and what 
>minimum traces can be obtained by each of the options you mentioned.  I've 
>traditionally used FeCl, but just picked up some Ammonium Persulphate (MG 
>Brand) but haven't tried it yet.  Also, the ammonium fumes may be a problem 
>so I'm not trying to get as much info as possible before I actually try it.
>
>Cheers,
>-Neil.
>
>
>On Thursday 22 May 2003 10:23, Marty Grove scribbled:
>> <lots o' stuff>
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>

Hello Neal.

 

I'm assuming that you are asking how clean the lines are after etch (as
opposed to how clean the etchant is after you have etched some boards).  I
you are using the "swish the board around in the solution" method, I cannot
say how the lines will turn out (I have practically no experience with that
method of etching).  I would imagine they would be okay down to a certain
width, but at some point I would think that the "swish" method would produce
ragged, uneven, and/or broken circuits for a number of reasons. poor
chemistry distribution, chemistry out of range (out of specification),
chemistry getting up-under the resist, etc. 

 

Our equipment was applying the chemistry to the board by spray.  If all of
the nozzles were properly clean, and the oscillation system that sprayed the
chemistry was operating correctly (and the chemistry was in specification),
the application of etchant was very evenly applied to the board(s).  The
impact of the spray on the board (the impingement) speeds up the etching
process considerably.  When using a high quality photo-resist and everything
was working properly (including artwork, imaging, applying the resist, and
developing), we were able to achieve line spaces and widths as small as 5 to
3 mil's with typically nice straight lines, and the industry is currently
trying to get even tighter tolerances.  I once read that in another 8 to 10
years, the industry wants to consistently achieve 1 mil lines and spaces.
<whew>

 

I'm curious as to whether anyone has built their own home spray etcher (a
small bench-top machine)?  It would be fairly easy (albeit the time and
components required).

 

Cheers to you too!  I'm guessing you're in the U.K.  I'll be visiting the
U.K. in about two months.  Although I've made several business trips over
there, this will be my first vacation (holiday).  I'm looking forward to it!

 

Marty

-----Original Message-----
From: Neil [mailto:cobra_neil@...] 
Sent: Thursday, May 22, 2003 12:21 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Etchant options?

 

Hi Marty,

Interesting info.  Thanks.

Would you have any info relating to how clean the final etch is, and what 
minimum traces can be obtained by each of the options you mentioned.  I've 
traditionally used FeCl, but just picked up some Ammonium Persulphate (MG 
Brand) but haven't tried it yet.  Also, the ammonium fumes may be a problem 
so I'm not trying to get as much info as possible before I actually try it.

Cheers,
-Neil.
 



[Non-text portions of this message have been removed]

On Thursday 22 May 2003 12:07, Stefan Trethan scribbled:
> i think all processes are capable of providing nearly the same results if
> used properly. the one thing is the resist, it must be suited for the
> etchant.

I use the positive photo-resist boards from MG.


> the second, underetching under the resist, can be prevented if the process
> is used the right way. i think if all is right (aeriation if needed,
> stirring, heating) and all is set up to result in a even etch over the
> whole board there is nearly no under-etching.

Doing all that -- agitation and heating.


> i think the most of the listed processes are also used in professional
> setups(some more often, some less).
> therefore they all should be suitable to provide perfect results.
>
> i think for setting up a etch it is important to consider the following:
> availability of the chemicals.

Yep -- I found Ammonium Persulphate at Fry's, which is why I thought I'd try 
it, instead of FeCl, which I was getting from RadioShack.


> disposal regulations / possibilities.

Still need to investigate this for Ammonium Persulphate.


> required speed.

It's been taking me 10-15 mins or so for FeCl.  Whereas a few minutes would be 
really nice, I'm willing to compromise here.


> available room.

Bathroom.  In a apartment for now, so no garage.  I can do this out on the 
patio, but I avoid anything outdoors since I've had bugs get in it before.


> time you want to invest, money you want to invest.

Time I can get.  Money, as little as possible :-)


> very important: number of pcbs per time unit you want.

I make one PCB every week (on average).  I'm in no rush.


> ability to build etching compartments (more complicated with
> spraying/aeration)

I'm in the middle of doing this now -- re-building my etching "system".  I'm 
using tall, slimmish plastic containers.  They have covers, so I intend to 
leave the solutions in the containers for the next time.  Once I have it 
setup, I'll write it up.


> you can use methods which need virtually no preparation/maintainance but
> also need more time/money when actually making a pcb. but in methods like
> cucl you have to prepare the etch quite a time before and also you need
> time for regeneration etc.
>
>
> if you really want to make pcbs in your garage you have to read
> descriptions for all methods. you have to look at your stores what you can
> get easily. only then you can decide. you will soon find arguments against
> the one or other method.

Yep, which is why I'm on this list. :-)
>
>
> regards
> st

Thanks,
-Neil.

On Thursday 22 May 2003 12:17, Marty Grove scribbled:
> Hello Neal.
>
> I'm assuming that you are asking how clean the lines are after etch (as
> opposed to how clean the etchant is after you have etched some boards).  I

Yes, exactly.


> you are using the "swish the board around in the solution" method, I cannot
> say how the lines will turn out (I have practically no experience with that
> method of etching).  I would imagine they would be okay down to a certain
> width, but at some point I would think that the "swish" method would
> produce ragged, uneven, and/or broken circuits for a number of reasons.
> poor chemistry distribution, chemistry out of range (out of specification),
> chemistry getting up-under the resist, etc.

I had been using a flat tray, with the board sitting flat on it, and I'd 
heat/stir with a small hairdryer aimed so that the solution swirls in 
circles.  And I flip the board every few minutes. Got better results than 
shaking manually every few minutes.  Recently picked up an air pump for my 
new PCB "system" so I expect better results.


> Our equipment was applying the chemistry to the board by spray.  If all of
> the nozzles were properly clean, and the oscillation system that sprayed
> the chemistry was operating correctly (and the chemistry was in
> specification), the application of etchant was very evenly applied to the
> board(s).  The impact of the spray on the board (the impingement) speeds up
> the etching process considerably.  When using a high quality photo-resist
> and everything was working properly (including artwork, imaging, applying
> the resist, and developing), we were able to achieve line spaces and widths
> as small as 5 to 3 mil's with typically nice straight lines, and the

Interesting you mention spray.  I was looking into this for rinsing my boards 
(thinking ouf using spray nozzles from a car windshield washer) and thought a 
about it for etchant, but decided to choose an etchant before investigating 
if the etchant would corrode/damage the pump.  I would ask what spray system 
you use, but my guess is that anything industry-specific will be $$$.


> industry is currently trying to get even tighter tolerances.  I once read
> that in another 8 to 10 years, the industry wants to consistently achieve 1
> mil lines and spaces. <whew>

Heard similar as well.  I went to a PCB trade show late last year, and saw 
some 3-mil boards, and 40-layer boards .... holy #$%*&#@* !!!

Luckily I only need 10 mil for now, but need to get it consistent.  I'd like 
to make my system a "science" rather than an "art".


> I'm curious as to whether anyone has built their own home spray etcher (a
> small bench-top machine)?  It would be fairly easy (albeit the time and
> components required).

Someday.


> Cheers to you too!  I'm guessing you're in the U.K.  I'll be visiting the
> U.K. in about two months.  Although I've made several business trips over
> there, this will be my first vacation (holiday).  I'm looking forward to
> it!
>
>
>
> Marty
>

Actually, I'm in the US, but not sure where I got cheers from.  I lived in 
London for a year a few years ago, but I was using cheers before that.  And I 
doubt that I got it from my original home in the Caribbean.

Cheers,
-Neil.

>Interesting you mention spray.  I was looking into this for rinsing my boards 
>(thinking ouf using spray nozzles from a car windshield washer) and thought a 
>about it for etchant, but decided to choose an etchant before investigating 
>if the etchant would corrode/damage the pump.  I would ask what spray system 
>you use, but my guess is that anything industry-specific will be $$$.

Neil

As Marty stated, constucting a spraying etcher is not that difficult.
I have one for home use that I bought from a small german company.
Anyways, all it (basically) consist of is a plastic container. From
the top to bottom there is a tube with fine holes in it. The tube is
turned from a motor that is mounted on top of the box cover. The tube
is having three bigger holes on it's lower end (it's otherwise
closed). This end is then placed so as it reaches the etchant floating
on the bottom of the box. The etchant enters the tube from the bottom.
Since the tube turns quickly, the etchant is then pressed towards the
tube walls and since there are small holes it leaves the tube therby
spraying.

Unfortunately the guy running this company seems to be a bit an a* and
I don't recommend buying from him dut to several reasons. I don't want
to go into these details here cause this is a group about PCB's and
not one to discuss political stuff. Anyways, I created a little page
for you that showes three pictures of the device so as you get the
idea. 

http://www.myhome.ch/mzingg/pcbstuff/

Markus

Hi all

I would like to hear from you guys if it's possible to create a
professional looking solder stop mask for PCB's. Is there a foil or
such that could be laminated and photochemically treated etched or
something? Anything possible? Marty do you have an idea?

Markus

Marty,

I built a small spray etcher many years ago using a "Little Giant" 
pump and a quartz heater for use with ferric chloride. Now I use this 
same unit to develop dry film photoresist. I used some HCL to clean 
out the ferric chloride stains and it works great for dry film. This 
etcher was modeled after the Kepro units but is just a bit larger so 
it can handle a 18" x 24" panel. My main etcher now is an old Chemcut 
315 which has oscillating spray bars and uses ferric chloride. 

I use Micromat drilling machines, one for drilling and one dedicated 
for routing. For prototypes I just use a scope drill. We soldermask 
all of our boards mainly to keep the copper from tarnishing. I just 
make boards for my own products and don't operate as a merchant shop 
any longer. 

Tom

=================================================================

Marty wrote:

I'm curious as to whether anyone has built their own home spray 
etcher (a
small bench-top machine)? It would be fairly easy (albeit the time and
components required).



Cheers to you too! I'm guessing you're in the U.K. I'll be visiting 
the
U.K. in about two months. Although I've made several business trips 
over
there, this will be my first vacation (holiday). I'm looking forward 
to it!



Marty

if you want to keep it "portable" you may try such a cooling container (the insulatet box for keeping 
things cold without active cooling system).
this has a lid on it.
but it is best for etchants which can stay there exposed to air and can be reused (regenerated) like the 
cucl with air regeneration.
(you have read all the cucl posts here?)

but if you want to try, for example one of the hydrogen peroxyde using processes i think it is better to 
have several smaller containers because the h2o2 is volatile. if you only use a small amount of etchant 
you only have to replenish a small amount of h2o2 to activate.

well, you have bought Ammonium Persulphate, i never tried this.
i don't know if it can be reused, is good to spray etc.

i would NOT recommend fe3cl. simply because a tiny drop stains everything.
i also don't like the etching speed (without suitable heating and agitation).
i still have some bags of fe3cl here which i never used. (here i'm talking about the cheap yellow stuff, 
not the "sublimate"? was it called so?)

are you sure you want to stay with Ammonium Persulphate?
you want to heat? agitation (bubbles?)?
having a bubbler on the bottom has resulted in stronger etching on the bottom (with cucl).


regards
stefan

In a message dated 5/22/2003 11:19:54 AM Central Standard Time, 
cobra_neil@... writes:

> Also, the ammonium fumes may be a problem 
> so I'm not trying to get as much info as possible before I actually try it.

Neil:  

Be CERTAIN you either put that ammonium persulfate stuff in a GLASS 
container, or use it up FAST, if it arrives in plastic!  I bought a "minimum order" 
(what was it, 2 lb?) once; came in a plastic container with screw-lid, so I put 
it on the BOTTOM shelf of a cabinet after just TRYING some, and FORGOT about 
it.  Within six months, it had eaten through the plastic container, the bottom 
(MDF) bookshelf, and the $$ carpet below!  Dum!  Need I recall the 
"conversation" with my wife over that?????           Jan Rowland


[Non-text portions of this message have been removed]

isn't this done by silkscreen printing?
all i know a about this is that you have a screen which is coated with photoresist.
this has to be exposed pretty much like a pcb.
then you can apply the color from the top (with a roller??).

this can't be too difficult if you can get the material.
i know of people having done t-shirt printing this way.

as you are in .ch:
http://www.altesspital.ch/i_werken.html they have "siebdruck" equipment, maybe try to ask them where 
they get it?

there are (quite big) screens at ebay.de for two additional days from now... maybe have a look.


i found something much better: (more familiar)
there is also a optical method:
http://www.peters.de/saved/ref149d.htm
i assume you speak german.
in principle it is applying a laquer and then exposing it.
afterwards the unwanted parts are developed off with sodium carbonate or alcohol.
then it is hardened.

seems quite simple.
as i don't want to make this (no need) i don't search further. please tell us if you find better 
descriptions/sources.

regards
stefan


22.05.2003 20:27:11, Markus Zingg <m.zingg@...> wrote:

>Hi all
>
>I would like to hear from you guys if it's possible to create a
>professional looking solder stop mask for PCB's. Is there a foil or
>such that could be laminated and photochemically treated etched or
>something? Anything possible? Marty do you have an idea?
>
>Markus
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>

This is a good question. I hadn't thought of this while considering the
possibilities of building boards at home.  Although I rarely got involved
with the solder masking of boards. I generally worked around the wet
processing steps. developing, etching, & stripping, and chemical /
mechanical cleaning, the processes that I am aware of are liquid solder mask
(typically applied by screen printing) and dry film solder mask.  Both
methods require special equipment; not something I would think would fall
into the "homebrew" category.

 

I also seen some solder masks that were applied via a plating process (i.e.
dip tank).  They were some composition of metals that were applied directly
to the traces, but again this is out of my realm of knowledge.  However..

 

I did a quick Internet search using keywords of the above items (solder
mask, dry film, screening, dip tank.) and I found the following link:
http://www.cam.org/~burt/circuits/sol-coat.html

 

This might be a viable solution for those who are making only a few boards.
The process seems time consuming, but at least its "do-able" at home.  I
especially like the idea of installing the components and performing the
soldering / solder mask steps at the same time.

 

Anyone else have solder mask techniques to share?  

 

Marty

-----Original Message-----
From: Markus Zingg [mailto:m.zingg@...] 
Sent: Thursday, May 22, 2003 2:27 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Creating a professional looking solder stopp mask

 

Hi all

I would like to hear from you guys if it's possible to create a
professional looking solder stop mask for PCB's. Is there a foil or
such that could be laminated and photochemically treated etched or
something? Anything possible? Marty do you have an idea?

Markus





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[Non-text portions of this message have been removed]

Hi Tom.

 

I'm very familiar with the 315.  I would think that would be a great etcher
for home brewing pcb's.  

 

Marty

-----Original Message-----
From: twb8899 [mailto:twb8899@...] 
Sent: Thursday, May 22, 2003 2:27 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Etchant options?

 

Marty,

I built a small spray etcher many years ago using a "Little Giant" 
pump and a quartz heater for use with ferric chloride. Now I use this 
same unit to develop dry film photoresist. I used some HCL to clean 
out the ferric chloride stains and it works great for dry film. This 
etcher was modeled after the Kepro units but is just a bit larger so 
it can handle a 18" x 24" panel. My main etcher now is an old Chemcut 
315 which has oscillating spray bars and uses ferric chloride. 

I use Micromat drilling machines, one for drilling and one dedicated 
for routing. For prototypes I just use a scope drill. We soldermask 
all of our boards mainly to keep the copper from tarnishing. I just 
make boards for my own products and don't operate as a merchant shop 
any longer. 

Tom

=================================================================

Marty wrote:

I'm curious as to whether anyone has built their own home spray 
etcher (a
small bench-top machine)? It would be fairly easy (albeit the time and
components required).



Cheers to you too! I'm guessing you're in the U.K. I'll be visiting 
the
U.K. in about two months. Although I've made several business trips 
over
there, this will be my first vacation (holiday). I'm looking forward 
to it!



Marty






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[Non-text portions of this message have been removed]

Hi Marty & Steve

Thanks for the pointers. I'm willing to take some effort to get a real
solder stop mask. 

@Marty - I would be especialy interested how the dry film solder mask
technique works. I'm ready to let some dollars roll. I usually don't
need a solder stop mask since I'm hand soldering my prototypes, but
there are ocasions where I must create a prototype in a short time
that should look like one made in a board house and where time does
not allow to have it made externally. Could you therefore elaborate a
bit on how this is done, what equipement is needed, what a simple one
would aproximately cost and possibly where to get it?

@Steve - thanks for the pointers. I defniately will go through them.

Markus

>This is a good question. I hadn't thought of this while considering the
>possibilities of building boards at home.  Although I rarely got involved
>with the solder masking of boards. I generally worked around the wet
>processing steps. developing, etching, & stripping, and chemical /
>mechanical cleaning, the processes that I am aware of are liquid solder mask
>(typically applied by screen printing) and dry film solder mask.  Both
>methods require special equipment; not something I would think would fall
>into the "homebrew" category.
>
> 
>
>I also seen some solder masks that were applied via a plating process (i.e.
>dip tank).  They were some composition of metals that were applied directly
>to the traces, but again this is out of my realm of knowledge.  However..
>
> 
>
>I did a quick Internet search using keywords of the above items (solder
>mask, dry film, screening, dip tank.) and I found the following link:
>http://www.cam.org/~burt/circuits/sol-coat.html
>
> 
>
>This might be a viable solution for those who are making only a few boards.
>The process seems time consuming, but at least its "do-able" at home.  I
>especially like the idea of installing the components and performing the
>soldering / solder mask steps at the same time.
>
> 
>
>Anyone else have solder mask techniques to share?  
>
> 
>
>Marty
>
> 
>
>-----Original Message-----
>From: Markus Zingg [mailto:m.zingg@...] 
>Sent: Thursday, May 22, 2003 2:27 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Creating a professional looking solder stopp mask
>
> 
>
>Hi all
>
>I would like to hear from you guys if it's possible to create a
>professional looking solder stop mask for PCB's. Is there a foil or
>such that could be laminated and photochemically treated etched or
>something? Anything possible? Marty do you have an idea?
>
>Markus
>
>
>
>
>
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I think this is also a great question - how to apply solder mask at home.

For all you chemical gurus on this list, couldn't you mix up a solution of
wet solder mask material, put it in a 'drafting pen' and then use an HP
plotter to 'draw' the solder mask on the board? You would just have to
create a file that draws everywhere you want the mask to be. That isn't
hard. The hard part (to me) is to find the right stuff to put in the pen. I
would assume that you'd then have to bake the board in an oven or something
to get the liquid solder mask to dry.

Can the same thing be done for do-it-yourself silk screen? I would guess so.
We'd just need the right 'ink' to put in the pen and then draw on the silk
screen layer. What type of ink could one use?

*Brian

I've done a couple different things as far as masking at home. 
Acrylic floor polish works fairly well as long as you're using it to
protect the copper and not sending it through some type of oven/reflow
machine.  Because the coating is pretty vulnerable to solder
temperatures it's a simple matter to first completely coat the board and
let it dry.  Afterward a soldering iron will go right through the stuff
without interfering with the solder wicking and so forth.  Makes for a
shiny, very nice looking board.  I use liquid flux and so ideally you'd
be able to dissolve it without affecting the acrylic; I'm not sure this
would be possible, although you could simply strip the board and then
recoat the board.
  I've also used dry-film resist as solder mask.  Again, you end up with
remainders of whatever flux you use when soldering, but I expect the
resist would be tough enough to stand up to a mild solvent for a short
time.  Gives the board a very "high-tech" look with a very high contrast
between the dark blue resist and the silver solder/copper pads.  The
artwork for this is easy enough to make, as it's simply an inverted
version of the mask used to expose the board originally.  Likewise, you
can use the dry-film resist as a poor-man's silk-screen for either side
of the board.  Because it's so dark blue it looks wonderful, and is
pretty robust.  I don't think I'll ever spring for real photo-resist; it
starts at $135 for a 40 foot roll and I only coat boards when I'm really
concerned about long-term performance.

  In regards to dry-film resist, I really think people overestimate how
difficult it is to apply.  There are definitely some important tricks
that you need when using it, but with those in hand you can do very
high-quality, cheap boards.  The best part is, if you mess up
exposing/coating a board you can just strip it and start fresh.  The
resist is sold from think-n-tinker
(http://www.thinktink.com/stack/volumes/voli/store/specs/m115spec.htm)
and for about $70 you can get enough resist (50 feet on a 12 inch roll)
to last for a LONG time.  Theoretically the stuff goes bad over time,
but as long as you keep it cool (no temps above 80 degrees preferably)
it will be good for several years.  I expect in a production environment
its characteristics change a bit over time which causes them problems
that a person using it on-and-off would never notice.  I'm not
affiliated with TNT, just a happy customer.  If anyone is interested, I
can share some of the things I've discovered over the years.

Larry

On Thu, 2003-05-22 at 13:43, Brian Schmalz wrote:
> I think this is also a great question - how to apply solder mask at
> home.
> 
> For all you chemical gurus on this list, couldn't you mix up a
> solution of
> wet solder mask material, put it in a 'drafting pen' and then use an
> HP
> plotter to 'draw' the solder mask on the board? You would just have to
> create a file that draws everywhere you want the mask to be. That
> isn't
> hard. The hard part (to me) is to find the right stuff to put in the
> pen. I
> would assume that you'd then have to bake the board in an oven or
> something
> to get the liquid solder mask to dry.
> 
> Can the same thing be done for do-it-yourself silk screen? I would
> guess so.
> We'd just need the right 'ink' to put in the pen and then draw on the
> silk
> screen layer. What type of ink could one use?
> 
> *Brian
>

Hello Markus,

22. May 2003, 22:35:57, you wrote:

MZ> Hi Marty & Steve

MZ> Thanks for the pointers. I'm willing to take some effort to get a real
MZ> solder stop mask. 

MZ> @Marty - I would be especialy interested how the dry film solder mask
MZ> technique works. I'm ready to let some dollars roll. I usually don't
MZ> need a solder stop mask since I'm hand soldering my prototypes, but
MZ> there are ocasions where I must create a prototype in a short time
MZ> that should look like one made in a board house and where time does
MZ> not allow to have it made externally. Could you therefore elaborate a
MZ> bit on how this is done, what equipement is needed, what a simple one
MZ> would aproximately cost and possibly where to get it?

MZ> @Steve - thanks for the pointers. I defniately will go through them.

MZ> Markus

www.thinktink.com

This is the place where you can spend some of your $$

A little bit more at:

http://www.thinktink.com/stack/volumes/volvi/pholam.htm


-- 
 Best Regards,
 Zoran
 mailto:zasto@...

I use a screen printed soldermask that is UV cured. There are many 
suppliers of this ink and mine is made by Taiyo. We make a silksceen 
using Autotype Five Star indirect film emulsion on a 180 mesh screen 
fabric. Aluminum frames should be used for best results since the 
wood types can't hold the required screen tension for very long. 

Taiyo also offers a liquid photo imageable mask. The circuit board 
is "flood coated" using a blank 110 mesh screen and then cured at 180 
degrees F until "tack free" but not fully cured. A film positive is 
then used to expose the required pattern. The exposed panel is 
developed in a 1% soda ash solution. After development the panel is 
baked at about 300 degrees F for 45 to 60 minutes.

DuPont used to make a dry film solder mask. We used their 8140 series 
dry film solder mask but I don't think they make it any longer. The 
liquid photo imageable types have taken over the market. It's very 
difficult to apply these dry film masks without using a vacuum 
laminator. We never did care much for the results and this was after 
wasting $48,000 on a DuPont vacuum laminator. The liquid types work 
much better. 

The only time anyone really uses the dry film masks now days is when 
they need to "tent" or cover over drilled holes with the exposed mask 
which is rare. Dry film and liquid photo imageable solder mask both 
require a huge amount of UV power to expose them properly. We used an 
ORC 5 kW exposure unit for this purpose. It had water cooled lamps 
since the heat from the lamps could damage the panel being exposed. 

If the board gets too hot during exposure the film photo tool will 
stick to the panel and make a big mess. By water cooling the lamp 
only the UV light gets through and the films don't stick. 

I think the silk screen method would be the best way to go for the 
home shop. You can cure UV screen printed inks with a mercury vapor 
lamp or just print the two part epoxy solder mask that is cured in a 
regular oven.

Tom

--- In Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic" 
<zasto@y...> wrote:
> Hello Markus,
> 
> 22. May 2003, 22:35:57, you wrote:
> 
> MZ> Hi Marty & Steve
> 
> MZ> Thanks for the pointers. I'm willing to take some effort to get 
a real
> MZ> solder stop mask. 
> 
> MZ> @Marty - I would be especialy interested how the dry film 
solder mask
> MZ> technique works. I'm ready to let some dollars roll. I usually 
don't
> MZ> need a solder stop mask since I'm hand soldering my prototypes, 
but
> MZ> there are ocasions where I must create a prototype in a short 
time
> MZ> that should look like one made in a board house and where time 
does
> MZ> not allow to have it made externally. Could you therefore 
elaborate a
> MZ> bit on how this is done, what equipement is needed, what a 
simple one
> MZ> would aproximately cost and possibly where to get it?
> 
> MZ> @Steve - thanks for the pointers. I defniately will go through 
them.

> 
> MZ> Markus
> 
> www.thinktink.com
> 
> This is the place where you can spend some of your $$
> 
> A little bit more at:
> 
> http://www.thinktink.com/stack/volumes/volvi/pholam.htm
> 
> 
> -- 
>  Best Regards,
>  Zoran
>  mailto:zasto@y...

FeCl3 stains can be removed with dilute HCl. If you stain some
clothing, just soak in bucket of water with a "splash" of
concentrated HCl, leave overnight.

Ammonium persulphate does not fume, unless you add a strong base
like sodium hydroxide which will release the ammonium ion as
ammonia gas, and only then will smell. Kind of like how table
salt doesn't smell like chlorine gas even though it contains
chlorine atoms.

Adam

Neil wrote:

> Hi Marty,
> 
> Interesting info.  Thanks.
> 
> Would you have any info relating to how clean the final etch is, and what 
> minimum traces can be obtained by each of the options you mentioned.  I've 
> traditionally used FeCl, but just picked up some Ammonium Persulphate (MG 
> Brand) but haven't tried it yet.  Also, the ammonium fumes may be a problem 
> so I'm not trying to get as much info as possible before I actually try it.
> 
> Cheers,
> -Neil.
> 
> 
> On Thursday 22 May 2003 10:23, Marty Grove scribbled:
> 
>><lots o' stuff>
> 
> 
> 
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
> 
>  
> 
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
> 
>

Jan,

Your Ammonium Persulphate story reminds me of the movie "Alien". :-)

When I picked up the AP, I did so for one specific reason ... Fry's was out of 
my usual FeCl.  So I thought I'd give this a try.  The container has it 
clearly marked on the front that plastic is fine.  But I spoke with MG's tech 
support and they told me the same thing -- I cannot leave it in a plastic 
container for a long time.  It will crystallize over time, concentrations 
will vary, and any fumes escaping will eventually render it inert.

No I'm not a chemist or even close, so I never investigated all the effects.

My intention was that now that I'm settled back in an apartment, I was setting 
up my PCB system so that I can leave the solutions in the containers for a 
long time ... weeks, months, etc.  I will be making prototypes regularly over 
the next few months.

So I returned the AP to the store, and they had FeCl in stock today, so I'm 
back to old faithful.  I've learned about its staining ability in the past, 
so I've learned to be drip-free / spill-free.  My new setup will make that 
even easier.

Cheers,
-Neil.



On Thursday 22 May 2003 14:17, JanRwl@... scribbled:

> In a message dated 5/22/2003 11:19:54 AM Central Standard Time,
>
> cobra_neil@... writes:
> > Also, the ammonium fumes may be a problem
> > so I'm not trying to get as much info as possible before I actually try
> > it.
>
> Neil:
>
> Be CERTAIN you either put that ammonium persulfate stuff in a GLASS
> container, or use it up FAST, if it arrives in plastic!  I bought a
> "minimum order" (what was it, 2 lb?) once; came in a plastic container with
> screw-lid, so I put it on the BOTTOM shelf of a cabinet after just TRYING
> some, and FORGOT about it.  Within six months, it had eaten through the
> plastic container, the bottom (MDF) bookshelf, and the $$ carpet below! 
> Dum!  Need I recall the "conversation" with my wife over that?????         
>  Jan Rowland
>
>
> [Non-text portions of this message have been removed]
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
> ---
> [This E-mail scanned for viruses]

No, I'm not sure I want to use Ammonium Persulphate, so I returned it.  Back 
to FeCl.  I think I can manage to avoid spilling any  ..... famous last 
words! :-)

I haven't followed all the CuCl posts, cause I had no intention of using it, 
and am not the type to go chase down this stuff.  But I think I'll go back 
thru the archives now.

Cheers,
-Neil.



On Thursday 22 May 2003 13:52, Stefan Trethan scribbled:

> if you want to keep it "portable" you may try such a cooling container (the
> insulatet box for keeping things cold without active cooling system).
> this has a lid on it.
> but it is best for etchants which can stay there exposed to air and can be
> reused (regenerated) like the cucl with air regeneration.
> (you have read all the cucl posts here?)
>
> but if you want to try, for example one of the hydrogen peroxyde using
> processes i think it is better to have several smaller containers because
> the h2o2 is volatile. if you only use a small amount of etchant you only
> have to replenish a small amount of h2o2 to activate.
>
> well, you have bought Ammonium Persulphate, i never tried this.
> i don't know if it can be reused, is good to spray etc.
>
> i would NOT recommend fe3cl. simply because a tiny drop stains everything.
> i also don't like the etching speed (without suitable heating and
> agitation). i still have some bags of fe3cl here which i never used. (here
> i'm talking about the cheap yellow stuff, not the "sublimate"? was it
> called so?)
>
> are you sure you want to stay with Ammonium Persulphate?
> you want to heat? agitation (bubbles?)?
> having a bubbler on the bottom has resulted in stronger etching on the
> bottom (with cucl).
>
>
> regards
> stefan
>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
> ---
> [This E-mail scanned for viruses]

Markus,
Can you tell us the size of the holes at the bottom (inlet) and the sides (outlet) of the spray tubes? Thanks
Regards
John C.

-----Original Message-----
From: Markus Zingg [mailto:m.zingg@...]
Sent: Friday, 23 May 2003 4:25 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Etchant options?

 From the top to bottom there is a tube with fine holes in it. The tube is
turned from a motor that is mounted on top of the box cover. The tube
is having three bigger holes on it's lower end (it's otherwise
closed). 

http://www.myhome.ch/mzingg/pcbstuff/

Markus


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i would really try to use the photosensitive laquer which is developed with soda ash.
i think you can apply this without using the screen.
maybe spraying is an option.
then proceed it very like a normal pcb.
(someone sayd solder stop is simply the negative of the copper artwork - this is not true because you 
want your tracks covered. but any pcb software should be able to produce it. if not make a layer with no 
traces but (bigger) pads. invert and print.)

i don's see any advantage in using the screen print method where you have to make the screen first if 
you can get laquer which already is photo sensitive. this would only add a unneccesary step?

or is there no photosensitive coating which doesn't need high power UV?


regards
stefan





23.05.2003 01:34:34, "twb8899" <twb8899@...> wrote:

>I use a screen printed soldermask that is UV cured. There are many 
>suppliers of this ink and mine is made by Taiyo. We make a silksceen 
>using Autotype Five Star indirect film emulsion on a 180 mesh screen 
>fabric. Aluminum frames should be used for best results since the 
>wood types can't hold the required screen tension for very long. 
>
>Taiyo also offers a liquid photo imageable mask. The circuit board 
>is "flood coated" using a blank 110 mesh screen and then cured at 180 
>degrees F until "tack free" but not fully cured. A film positive is 
>then used to expose the required pattern. The exposed panel is 
>developed in a 1% soda ash solution. After development the panel is 
>baked at about 300 degrees F for 45 to 60 minutes.
>
>DuPont used to make a dry film solder mask. We used their 8140 series 
>dry film solder mask but I don't think they make it any longer. The 
>liquid photo imageable types have taken over the market. It's very 
>difficult to apply these dry film masks without using a vacuum 
>laminator. We never did care much for the results and this was after 
>wasting $48,000 on a DuPont vacuum laminator. The liquid types work 
>much better. 
>
>The only time anyone really uses the dry film masks now days is when 
>they need to "tent" or cover over drilled holes with the exposed mask 
>which is rare. Dry film and liquid photo imageable solder mask both 
>require a huge amount of UV power to expose them properly. We used an 
>ORC 5 kW exposure unit for this purpose. It had water cooled lamps 
>since the heat from the lamps could damage the panel being exposed. 
>
>If the board gets too hot during exposure the film photo tool will 
>stick to the panel and make a big mess. By water cooling the lamp 
>only the UV light gets through and the films don't stick. 
>
>I think the silk screen method would be the best way to go for the 
>home shop. You can cure UV screen printed inks with a mercury vapor 
>lamp or just print the two part epoxy solder mask that is cured in a 
>regular oven.
>
>Tom
>
>--- In Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic" 
><zasto@y...> wrote:
>> Hello Markus,
>> 
>> 22. May 2003, 22:35:57, you wrote:
>> 
>> MZ> Hi Marty & Steve
>> 
>> MZ> Thanks for the pointers. I'm willing to take some effort to get 
>a real
>> MZ> solder stop mask. 
>> 
>> MZ> @Marty - I would be especialy interested how the dry film 
>solder mask
>> MZ> technique works. I'm ready to let some dollars roll. I usually 
>don't
>> MZ> need a solder stop mask since I'm hand soldering my prototypes, 
>but
>> MZ> there are ocasions where I must create a prototype in a short 
>time
>> MZ> that should look like one made in a board house and where time 
>does
>> MZ> not allow to have it made externally. Could you therefore 
>elaborate a
>> MZ> bit on how this is done, what equipement is needed, what a 
>simple one
>> MZ> would aproximately cost and possibly where to get it?
>> 
>> MZ> @Steve - thanks for the pointers. I defniately will go through 
>them.
>> 
>> MZ> Markus
>> 
>> www.thinktink.com
>> 
>> This is the place where you can spend some of your $$
>> 
>> A little bit more at:
>> 
>> http://www.thinktink.com/stack/volumes/volvi/pholam.htm
>> 
>> 
>> -- 
>>  Best Regards,
>>  Zoran
>>  mailto:zasto@y...
>
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>

look in the archives, i have already annoyed him with plenty of questions about this unit.

his tubes have a end plate with holes only i think.
if you can't get it working (not enough revs) i would try to glue in a small fan blade at the bottom end
(of this tiny computer fans). they are for air but also will work fine with liquid. this would propell 
more etchant up the tube, also at lower speeds. (but you need a amount of speed also to get it spraying 
nice.) (please remove the frame and motor part, the fan wheel is driven directly by the rotating pipe.

regards
stefan

the assembly would be more easy if you use a stainless steel rod (maybe plastic) with a few mm diameter.
this in beared on the bottom in some sleeve (plastic, ceramic).
in the top lid there is another bearing (no etchant contact here).

the rod stands out the top and has either a pulley or the motor directly attached.
at the now sturdy beared rod you simply glue the piece of pipe.

this i think is much easier to manufacture than a rod which is free at the bottom end.
if its cog is out of the center it will disintegrate when at very high revs, possibly leaving you with a 
very fast out of control rotating mass in a lot of etchant.

regards
stefan


23.05.2003 05:09:32, "John Craddock" <John.Craddock@...> wrote:

>Markus,
>Can you tell us the size of the holes at the bottom (inlet) and the sides (outlet) of the spray tubes? 
Thanks

>Regards
>John C.
>
>
>-----Original Message-----
>From: Markus Zingg [mailto:m.zingg@...]
>Sent: Friday, 23 May 2003 4:25 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Etchant options?
>
> From the top to bottom there is a tube with fine holes in it. The tube is
>turned from a motor that is mounted on top of the box cover. The tube
>is having three bigger holes on it's lower end (it's otherwise
>closed). 
>
>http://www.myhome.ch/mzingg/pcbstuff/
>
>Markus
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>

Hi John

Problem is that the unit I have is filled with etchant. I would have
to disassemble it to give much more precise information. I will do
this at a later time, but at the moment I'm really "full power" busy
to finish my plating trhough station. Also tonight I (finnaly) get my
first digital camera and hence will be able to take some pictures. I
first will put some info on the plating through machine online cause I
promissed this a while ago already. 

I think the etcher - while a fine unit - could be made even better.
For those interested, the archives also show the link to the
manufacturer of it - but again, if you visit his page you soon know
why I don't recomend buying there. Anyways, as soon as I have finished
the boards that I'm in the urgent need of I will have some more time
to experiment and - well time to disasemble the etcher and make more
detailed photos and measures etc.

@steve - you were not anoying me :-) It's just that I can't disasemble
the unit at the moment.

Markus

>Markus,
>Can you tell us the size of the holes at the bottom (inlet) and the sides (outlet) of the spray tubes? Thanks
>Regards
>John C.
>
>
>-----Original Message-----
>From: Markus Zingg [mailto:m.zingg@...]
>Sent: Friday, 23 May 2003 4:25 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Etchant options?
>
> From the top to bottom there is a tube with fine holes in it. The tube is
>turned from a motor that is mounted on top of the box cover. The tube
>is having three bigger holes on it's lower end (it's otherwise
>closed). 
>
>http://www.myhome.ch/mzingg/pcbstuff/
>
>Markus
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>

Thank you very much Markus. I loof forward to reading about both the through plating and the spray etcher at a time when you are less "snowed under".
Regards
John C

-----Original Message-----
From: Markus Zingg [mailto:m.zingg@...]
Sent: Friday, 23 May 2003 7:46 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Etchant options?


Hi John

Problem is that the unit I have is filled with etchant. I would have
to disassemble it to give much more precise information. I will do
this at a later time, but at the moment I'm really "full power" busy
to finish my plating trhough station. Also tonight I (finnaly) get my
first digital camera and hence will be able to take some pictures. I
first will put some info on the plating through machine online cause I
promissed this a while ago already. 

I think the etcher - while a fine unit - could be made even better.
For those interested, the archives also show the link to the
manufacturer of it - but again, if you visit his page you soon know
why I don't recomend buying there. Anyways, as soon as I have finished
the boards that I'm in the urgent need of I will have some more time
to experiment and - well time to disasemble the etcher and make more
detailed photos and measures etc.

@steve - you were not anoying me :-) It's just that I can't disasemble
the unit at the moment.

Markus

>Markus,
>Can you tell us the size of the holes at the bottom (inlet) and the sides (outlet) of the spray tubes? Thanks
>Regards
>John C.
>
>
>-----Original Message-----
>From: Markus Zingg [mailto:m.zingg@...]
>Sent: Friday, 23 May 2003 4:25 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Etchant options?
>
> From the top to bottom there is a tube with fine holes in it. The tube is
>turned from a motor that is mounted on top of the box cover. The tube
>is having three bigger holes on it's lower end (it's otherwise
>closed). 
>
>http://www.myhome.ch/mzingg/pcbstuff/
>
>Markus
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
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> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>



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Hello Markus.



I’ll take a look and see what all is needed for this and post something
a.s.a.p.



I thought id’ make a quick point to let everyone know that an excellent
place to find various PCB equipment (used, but often in excellent
functioning condition) is DoveBid   http://www.dovebid.com/



This is an auction house.  Many circuit board shops have been closing over
the past couple of years (do to many factors), and just about every one of
them auctions their items off through DoveBid.  I’ve been to a few of the
auctions, and I can tell you that all of the stuff is going for pennies on
the dollar.  With this in mind, this might be a good place to gather the
items you need for solder masking (as well as any items for home etching).



Marty

-----Original Message-----
From: Zoran A. Scepanovic [mailto:zasto@...]
Sent: Thursday, May 22, 2003 6:08 PM
To: Markus Zingg
Subject: Re: [Homebrew_PCBs] Creating a professional looking solder stopp
mask



Hello Markus,

22. May 2003, 22:35:57, you wrote:

MZ> Hi Marty & Steve

MZ> Thanks for the pointers. I'm willing to take some effort to get a real
MZ> solder stop mask.

MZ> @Marty - I would be especialy interested how the dry film solder mask
MZ> technique works. I'm ready to let some dollars roll. I usually don't
MZ> need a solder stop mask since I'm hand soldering my prototypes, but
MZ> there are ocasions where I must create a prototype in a short time
MZ> that should look like one made in a board house and where time does
MZ> not allow to have it made externally. Could you therefore elaborate a
MZ> bit on how this is done, what equipement is needed, what a simple one
MZ> would aproximately cost and possibly where to get it?

MZ> @Steve - thanks for the pointers. I defniately will go through them.

MZ> Markus

www.thinktink.com

This is the place where you can spend some of your $$

A little bit more at:

http://www.thinktink.com/stack/volumes/volvi/pholam.htm


--
Best Regards,
Zoran
mailto:zasto@...






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[Non-text portions of this message have been removed]

On Fri, 2003-05-23 at 00:24, Stefan Trethan wrote:
> i would really try to use the photosensitive laquer which is developed
> with soda ash.
> i think you can apply this without using the screen.
> maybe spraying is an option.
> then proceed it very like a normal pcb.
> (someone sayd solder stop is simply the negative of the copper artwork
> - this is not true because you 
> want your tracks covered. but any pcb software should be able to
> produce it. if not make a layer with no 
> traces but (bigger) pads. invert and print.)

  Whoops, that would be me.  Not sure what I was thinking when I wrote
that.  What I meant to say was I would plot a negative of the pattern
without traces.  Back on topic, can anyone tell me what type of liquid
photo-resist (available in the USA) they use which can give consistent,
repeatable results?  I've tried two types of liquid resist; one which
was developed using a caustic solution, and one which was developed
using a very aggressive solvent.  Neither one worked very well and I had
a terrible time getting consistent results.  Also, are any of this
liquid resists visible after exposure?  That's what I really enjoy about
the dry-film resist; the pattern is very clear after exposure and you
can usually tell when you've under/over-exposed just by looking at it.

Larry

all i know about liquod resist is the following:
its from a friend in hugary. he makes lots of prototypes, 0,15mm standard with.
always sprays on resist himself.
i didn't ask him for permission of posting this part of email but i think he would grant.

>> start
I detail tested the photopositive RESISTS:

POSITIVE 20
(KONTAKT CHEMIE)

CRAMOLIN POSITIVE RESIST ART.-NO. 126
(Chemische Produkte GmbH)

TN 120
(WOLF)

The TN 120 is big covering, develope quality is best, but
the resist not antistatic during lacking, and long drying time
1 day (the upper resist layer dry with high speed and slowing
the lower layer dry), totally unsensitive on color temperature
The lack is unsensitive for temperature too.
The price is low.

The POSITIVE 20 not antistatic, but sensitive for development
process (thermicaly), The pice is higher.

The CRAMOLIN 126 sensitive for good exposition time
and color temperature.

I recomending  POSITIVE 20 or TN 120
with 1 day dry (2 min on 60 C plus 24 hour 24C)

>> stop

(lack=laquer)
this are german companies (he is in hungary).
you may nor get in the u.s. but maybe it helps.


regards
stefan

>  Whoops, that would be me.  Not sure what I was thinking when I wrote
>that.  What I meant to say was I would plot a negative of the pattern
>without traces.  Back on topic, can anyone tell me what type of liquid
>photo-resist (available in the USA) they use which can give consistent,
>repeatable results?  I've tried two types of liquid resist; one which
>was developed using a caustic solution, and one which was developed
>using a very aggressive solvent.  Neither one worked very well and I had
>a terrible time getting consistent results.  Also, are any of this
>liquid resists visible after exposure?  That's what I really enjoy about
>the dry-film resist; the pattern is very clear after exposure and you
>can usually tell when you've under/over-exposed just by looking at it.
>
>Larry
>
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
> 
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
>
>
>

--- In Homebrew_PCBs@yahoogroups.com, "Marty Grove" <MartyGrove@c...>
wrote:
> This is a good question. I hadn't thought of this while considering the
> possibilities of building boards at home.  Although I rarely got
involved
> with the solder masking of boards. I generally worked around the wet
> processing steps. developing, etching, & stripping, and chemical /
> mechanical cleaning, the processes that I am aware of are liquid
solder mask
> (typically applied by screen printing) and dry film solder mask.  Both
> methods require special equipment; not something I would think would
fall
> into the "homebrew" category.

In a small semiconductor research lab in which I work, we regularly
apply photoresist to silicon wafers using a spinner.  Is there some
reason such a process, using a clamped PCB board and a
servo-controlled motor, couldn't work for applying liquid photoresist
to copper-clad boards, as well?  Seems to me almost a homebrew solution.

Jonathan

----- Original Message ----- 

From: "Jonathan W" <n0ym@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, May 24, 2003 5:35 AM
Subject: [Homebrew_PCBs] Re: Creating a professional looking solder stopp
mask
>
> In a small semiconductor research lab in which I work, we regularly
> apply photoresist to silicon wafers using a spinner.  Is there some
> reason such a process, using a clamped PCB board and a
> servo-controlled motor, couldn't work for applying liquid photoresist
> to copper-clad boards, as well?  Seems to me almost a homebrew solution.

This technique used to be used a lot for coating PCBs (before the adoption
of film resist), and I've heard of people using it at home with an ordinary
motor. Something like a large cardboard box is advisable to stop the room
and contents from being coated, as well. 8-)

Leon
--
Leon Heller, G1HSM
leon_heller@...
http://www.geocities.com/leon_heller

Jonathan,
I have used that process, even used the same resist at one of my former 
jobs. It worked ok once you get
a handle on applying the resist.
Bill Higdon
Jonathan W wrote:

> --- In Homebrew_PCBs@yahoogroups.com, "Marty Grove" <MartyGrove@c...>
> wrote:
> > This is a good question. I hadn't thought of this while considering the
> > possibilities of building boards at home.  Although I rarely got
> involved
> > with the solder masking of boards. I generally worked around the wet
> > processing steps. developing, etching, & stripping, and chemical /
> > mechanical cleaning, the processes that I am aware of are liquid
> solder mask
> > (typically applied by screen printing) and dry film solder mask.  Both
> > methods require special equipment; not something I would think would
> fall
> > into the "homebrew" category.
>
> In a small semiconductor research lab in which I work, we regularly
> apply photoresist to silicon wafers using a spinner.  Is there some
> reason such a process, using a clamped PCB board and a
> servo-controlled motor, couldn't work for applying liquid photoresist
> to copper-clad boards, as well?  Seems to me almost a homebrew solution.
>
> Jonathan
>

--- In Homebrew_PCBs@yahoogroups.com, Bill Higdon <w.higdon@a...> wrote:
> Jonathan,
> I have used that process, even used the same resist at one of my former 
> jobs. It worked ok once you get
> a handle on applying the resist.
> Bill Higdon


The photoresist we use in my lab is Clariant AZ5209 (useable as
positive or negative photoresist, depending upon the processing). 
Spinning at 4000 rpm gives you a .9um coating.

Does anyone know of other sources for photoresist, along with any
pricing info?  Just about the only one I know of is the Seno resist
sold through Mega Electronics.

Jonathan

Please accept my apologies. It was so quiet here lately (for me?) that
I'm not sure if my ISP blocks this list in his spam filters or such...

Markus