Homebrew PCBs

Hello all,
Wondering if anyone could point me in the right direction.
To find the correct exposure time I made up a strip of inkjet
transparent film with 10 identical dill sockets plus some lines,
placed this over a strip of "fotoboard 2" board (with glass holding
it all together) and placed it under a 2* 8W uv light for between 4
and 13 mins (uncovering each dill socket every minuite). I made up
the developing solution ratio 10:1, and placed the board in a glass
dish containg developer.
After about 1 min I started to see my image appear on the board and
a bluish residue around the exposed print. This seemed ok but did
not develop any more as left it in the solution for a couple of more
mins, then the print slowely started to dissapear to nothing. I
tried etching anyway but all I got was a nice clean board striped of
all copper and no tracks/sockets at all.
At least I know how to etch the board but I am confused why the
image started to develop and then dissapeared.

In case it helps I used fotoboard 2, pcb developer and pcb etchent
from maplins ( the products are made by chiltern and I had a 1:1
ratio of etchent to water)

Any help graetfully received

Kind regards Tbone

Hi Tbone,
put in the developer a unexposured pcb, it may not disolve the resist 
if it dos its to strong 
I think your to short in exposure time or maybe lights to far away-
3 to 4" is normal distance
And be shore that the daylight must be tempered a bit 

please excuse my bad english.

gr. Roel
 
--- In Homebrew_PCBs@yahoogroups.com, "tboneuk_2000" 
<a_reynolds@b...> wrote:

> Hello all,
> Wondering if anyone could point me in the right direction.
> To find the correct exposure time I made up a strip of inkjet
> transparent film with 10 identical dill sockets plus some lines,
> placed this over a strip of "fotoboard 2" board (with glass holding
> it all together) and placed it under a 2* 8W uv light for between 4
> and 13 mins (uncovering each dill socket every minuite). I made up
> the developing solution ratio 10:1, and placed the board in a glass
> dish containg developer.
> After about 1 min I started to see my image appear on the board and
> a bluish residue around the exposed print. This seemed ok but did
> not develop any more as left it in the solution for a couple of more
> mins, then the print slowely started to dissapear to nothing. I
> tried etching anyway but all I got was a nice clean board striped of
> all copper and no tracks/sockets at all.
> At least I know how to etch the board but I am confused why the
> image started to develop and then dissapeared.
> 
> In case it helps I used fotoboard 2, pcb developer and pcb etchent
> from maplins ( the products are made by chiltern and I had a 1:1
> ratio of etchent to water)
> 
> Any help graetfully received
> 
> Kind regards Tbone

I assume you are using "positive" acting resist, where the 
exposed portions of the resist become soluble in the developer.
If you experienced incomplete developing then it sounds like your 
13 minute maximum test was still not long enough. From my 
experience with positive resists, the unexposed resist will still 
dissolve in developer after extend period of time. Normally this 
time is significantly longer than the time it takes for exposed 
resist to dissolve, so the resist image can be left on the PCB.

Before testing with artworks, simply expose pieces of photoresist 
coated PCB and compare them with unexposed pieces. Try placing a 
piece out in the sun for 20+ minutes to guarantee full exposure, 
then compare that with unexposed piece.

Once you get a ball part figure of the exposure time, then you 
can refine it with the stepped method you did earlier.

Adam

tboneuk_2000 wrote:

> Hello all,
> Wondering if anyone could point me in the right direction.
> To find the correct exposure time I made up a strip of inkjet
> transparent film with 10 identical dill sockets plus some lines,
> placed this over a strip of "fotoboard 2" board (with glass holding
> it all together) and placed it under a 2* 8W uv light for between 4
> and 13 mins (uncovering each dill socket every minuite). I made up
> the developing solution ratio 10:1, and placed the board in a glass
> dish containg developer.
> After about 1 min I started to see my image appear on the board and
> a bluish residue around the exposed print. This seemed ok but did
> not develop any more as left it in the solution for a couple of more
> mins, then the print slowely started to dissapear to nothing. I
> tried etching anyway but all I got was a nice clean board striped of
> all copper and no tracks/sockets at all.
> At least I know how to etch the board but I am confused why the
> image started to develop and then dissapeared.
> 
> In case it helps I used fotoboard 2, pcb developer and pcb etchent
> from maplins ( the products are made by chiltern and I had a 1:1
> ratio of etchent to water)
> 
> Any help graetfully received
> 
> Kind regards Tbone
> 
> 
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs 
> 
> Yahoo! Groups Links
> 
> To visit your group on the web, go to:
>  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/ 
> 
>

Thanks Roel,
I will try an unexposed piece tommorow, the instructions stated 10mg 
of developer per 100ml of water. I did not have any scales to 
measure this amount so I could have put too much developer in the 
solution.
I have also just found another post that has had similar problems to 
this but he had the developer solution to hot, mine was around 20°c 
room tempreture so I do not think that is the problem.


--- In Homebrew_PCBs@yahoogroups.com, "roel_cnc" <atmelletje@g...> 
wrote:
> Hi Tbone,
> put in the developer a unexposured pcb, it may not disolve the 
resist 
> if it dos its to strong 
> I think your to short in exposure time or maybe lights to far away-
> 3 to 4" is normal distance
> And be shore that the daylight must be tempered a bit 
> 
> please excuse my bad english.
> 
> gr. Roel
>  
> --- In Homebrew_PCBs@yahoogroups.com, "tboneuk_2000" 
> <a_reynolds@b...> wrote:
> > Hello all,
> > Wondering if anyone could point me in the right direction.
> > To find the correct exposure time I made up a strip of inkjet
> > transparent film with 10 identical dill sockets plus some lines,
> > placed this over a strip of "fotoboard 2" board (with glass 
holding
> > it all together) and placed it under a 2* 8W uv light for 
between 4
> > and 13 mins (uncovering each dill socket every minuite). I made 
up
> > the developing solution ratio 10:1, and placed the board in a 
glass
> > dish containg developer.
> > After about 1 min I started to see my image appear on the board 
and
> > a bluish residue around the exposed print. This seemed ok but did
> > not develop any more as left it in the solution for a couple of 
more
> > mins, then the print slowely started to dissapear to nothing. I
> > tried etching anyway but all I got was a nice clean board 
striped of
> > all copper and no tracks/sockets at all.
> > At least I know how to etch the board but I am confused why the
> > image started to develop and then dissapeared.
> > 
> > In case it helps I used fotoboard 2, pcb developer and pcb 
etchent

> > from maplins ( the products are made by chiltern and I had a 1:1
> > ratio of etchent to water)
> > 
> > Any help graetfully received
> > 
> > Kind regards Tbone

Hi Tbone--

One teaspoon roughly equals 5 milliliters ... milliliters = milligrams =
centimeter-cubed in terms of water, so adjust accordingly.

Regards/Roger, in Bangkok

-----Original Message-----
....
.... I did not have any scales to measure this ...

Roger, in Bangkok wrote:

> Hi Tbone--
> 
> One teaspoon roughly equals 5 milliliters ... milliliters = milligrams =
> centimeter-cubed in terms of water, so adjust accordingly.
> 

Actually,

  milliliter = gram = centimeter cubed

Thanks everybody , here is a little more information

As both the developer and etchent were from the same company and in 
the same packaging I used an approximation like so:-

Etchent was in a 250 ml Bottle
Developer was in a 250mg Bottle

so knowing that a teaspoon is 5ml, roughly the same amoun of 
deveoper granuales on a teaspoon would be 5mg,

similar to this post 

--- In Homebrew_PCBs@yahoogroups.com, "Roger, in Bangkok" 
<mercies@c...> wrote:

> One teaspoon roughly equals 5 milliliters ... milliliters = 
milligrams =

I used 500ml of water with a 10:1 ratio of developer so I would need 
50mg of granuales or 10 teaspoons as an approximation, however as 
this post

--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" 
<leon_heller@h...> wrote:

>It sounds as if it was too strong, anyway - Fotoboard 2 uses half-
strength developer.

I also noted this so I only used 5 teaspoons (leveled not heaped to  
be on the safe side)


--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" 
<leon_heller@h...> wrote:
> Try agitating the developer by rocking the container continuously.

I did continuously keep the deveoper moving both by rocking and by 
moving a brush around the solution (not brushing the board, this did 
not come into contact with the board, just kept the solution moving)

hope that makes things a little clearer

Kind regards

Tbone

I have just looked at the film I used and discovered the print may 
have been the wrong way around. I presume the ink should have been 
next to the board, I had this the other way around so the light hit 
the ink printed on the film then had to pass through the transparent 
film itself before hitting the board.
Am I right in thinking this would effect the exposure efficientcy or 
will it not make any difference?
 
 Kind regards
 
 Tbone

On Wed, 04 Feb 2004 17:06:49 -0000, tboneuk_2000 
<a_reynolds@...> wrote:

> I have just looked at the film I used and discovered the print may
> have been the wrong way around. I presume the ink should have been
> next to the board, I had this the other way around so the light hit
> the ink printed on the film then had to pass through the transparent
> film itself before hitting the board.
> Am I right in thinking this would effect the exposure efficientcy or
> will it not make any difference?
>
>  Kind regards
>
>  Tbone
>
>

it is better to put the ink to the board because of undercutting of light, 
however i have made
a few boards the wrong way around and it always worked...
it should not affect the result in larger copper areas (e.g. a pad).

ST

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Wed, 04 Feb 2004 17:06:49 -0000, tboneuk_2000 
> <a_reynolds@b...> wrote:
> 
> > I have just looked at the film I used and discovered the print 
may
> > have been the wrong way around. I presume the ink should have 
been
> > next to the board, I had this the other way around so the light 
hit
> > the ink printed on the film then had to pass through the 
transparent
> > film itself before hitting the board.
> > Am I right in thinking this would effect the exposure 
efficientcy or
> > will it not make any difference?
> >
> >  Kind regards
> >
> >  Tbone
> >
> >
> 
> it is better to put the ink to the board because of undercutting 
of light, 
> however i have made
> a few boards the wrong way around and it always worked...
> it should not affect the result in larger copper areas (e.g. a 
pad).
> 
> ST

Although it may not make a differance I fliped the film over, so the 
ink faced the board.
My original trial board was exposed for 4 to 13 mins at 1 min 
intervals, now I tried exposing another board for 12 to 30 mins in 2 
min steps.
Still not developing, should I see an image of the transfer (even a 
faint image) before developing the board ?
One thing that may be worth mentioning is that for this second trial 
I used the same deveoping solution that I used for the first (is it 
normal to do this or should I have made anew batch for each 
development)..?
The original board had an image for few seconds then seem to 
dissapear in the solution, this new board exposed for longer had no 
such image. Could it be I need to expose for a much shorter time <4 
mins ?

Kind Regards 

Tbone

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

From: "tboneuk_2000" <a_reynolds@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, February 04, 2004 9:21 PM
Subject: [Homebrew_PCBs] Re: Dissapearing Tracks in deveoper


>
> Although it may not make a differance I fliped the film over, so the
> ink faced the board.
> My original trial board was exposed for 4 to 13 mins at 1 min
> intervals, now I tried exposing another board for 12 to 30 mins in 2
> min steps.
> Still not developing, should I see an image of the transfer (even a
> faint image) before developing the board ?

There should be a faint image visible if the exposure was OK.


> One thing that may be worth mentioning is that for this second trial
> I used the same deveoping solution that I used for the first (is it
> normal to do this or should I have made anew batch for each
> development)..?

You can reuse developer many times. I make my own from NaOH (about 12 g per
litre of water) and use it fresh each time as it's very cheap.

> The original board had an image for few seconds then seem to
> dissapear in the solution, this new board exposed for longer had no
> such image. Could it be I need to expose for a much shorter time <4
> mins ?

Sounds as if it was overexposed.

Leon

> Although it may not make a differance I fliped the film over, so the
> ink faced the board.

eliminate all unknown variables, good idea.

> My original trial board was exposed for 4 to 13 mins at 1 min
> intervals, now I tried exposing another board for 12 to 30 mins in 2
> min steps.
> Still not developing, should I see an image of the transfer (even a
> faint image) before developing the board ?

with the boards i used one could see a yellow/green discoloration
if you hold it at an agle against the light.

however if you put it in the developer and everything is correct you should
see instantly the pattern clearly showing against the exposed areas.

i remember that it looks like the image is "hovering" over the board
in the water for a few seconds if you have something wrong.
i tried to remember and tried to find the maual where i found the answer
but no luck. i think it means it is actually underexposed (and you have 
added
more developer to get things going).

> One thing that may be worth mentioning is that for this second trial
> I used the same deveoping solution that I used for the first (is it
> normal to do this or should I have made anew batch for each
> development)..?

it degrades with time, so (open)storage is no good, but it should 
definitely
last for some boards in a row.

> The original board had an image for few seconds then seem to
> dissapear in the solution, this new board exposed for longer had no
> such image. Could it be I need to expose for a much shorter time <4
> mins ?

this depends on the combination of light source and resist.
try it.
sorry that i can't help more, it seems i have forgotten the time when 
starting
with photoprocess.....

st

tboneuk_2000 wrote:
> 
> Although it may not make a differance I fliped the film over, so the 
> ink faced the board.
> My original trial board was exposed for 4 to 13 mins at 1 min 
> intervals, now I tried exposing another board for 12 to 30 mins in 2 
> min steps.
> Still not developing, should I see an image of the transfer (even a 
> faint image) before developing the board ?
> One thing that may be worth mentioning is that for this second trial 
> I used the same deveoping solution that I used for the first (is it 
> normal to do this or should I have made anew batch for each 
> development)..?
> The original board had an image for few seconds then seem to 
> dissapear in the solution, this new board exposed for longer had no 
> such image. Could it be I need to expose for a much shorter time <4 
> mins ?
> 
> Kind Regards 
> 
> Tbone

I think the makeup of positive photoresist developer solution is 10 +/-2 
grams per liter of sodium hydroxide. Are you using that ?
If you cannot measure in 1 g resolution then do this;
Get yourself;
   container of 98% NaOH powder (make sure its free flowing powder).
   750ml cleaned softdrink bottle with a non-metalic lid.
   (fill bottle with tap water about 3/4 full)
   small plastic funnel
   a pen, and a note pad.
   a plastic drinking cup

Go to the post office with the above items. Ask post worker you like to 
weigh some powder. Somewhere close to the scales setup the drink bottle 
with the funnel in the top. Put cup on scales, and record weight. Pour 
between 75 to 80g of NaOH into the cup and record total weight. Carfully 
take cup with NaOH and pour into the bottle using the funnel. Some NaOH may 
remain sticking to the cup sides so pour some of the water from the bottle 
into the cup and then pour back into bottle again. Put lids on and tell 
them thank you.

Top up the bottle with water so it has 750ml. Calculate and mark the bottle 
with the NaOH concentration. This will be your developer concentrate. You 
can now use simple kitchen volume measuring equipment to make up 10 +-2g 
g/L NaOH developer. Never resue developer.

Before worrying about exposure times, try as I said before, and expose a 
piece of PCB in the sun for 20+ minutes, put some black PVC tape on one 
half to block out the light. Then you have guaranteed exposure. Develope 
the PCB and see how it goes.

Hi Tbone,

    I think you are way overexposing it.
I use the sun ( I live in AZ ) and it only takes 30 to 35 seconds per side and I get perfect results every time ( 35 years of doing it this way). Also the sun is infinitely far away, as far as the resist is concerned, so I get sharp clear results
    Give it a try.

Jack

  ----- Original Message ----- 
  From: tboneuk_2000 
  To: Homebrew_PCBs@yahoogroups.com 
  Sent: Wednesday, February 04, 2004 2:21 PM
  Subject: [Homebrew_PCBs] Re: Dissapearing Tracks in deveoper


  --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
  <stefan_trethan@g...> wrote:
  > On Wed, 04 Feb 2004 17:06:49 -0000, tboneuk_2000 
  > <a_reynolds@b...> wrote:
  > 
  > > I have just looked at the film I used and discovered the print 
  may
  > > have been the wrong way around. I presume the ink should have 
  been
  > > next to the board, I had this the other way around so the light 
  hit
  > > the ink printed on the film then had to pass through the 
  transparent
  > > film itself before hitting the board.
  > > Am I right in thinking this would effect the exposure 
  efficientcy or
  > > will it not make any difference?
  > >
  > >  Kind regards
  > >
  > >  Tbone
  > >
  > >
  > 
  > it is better to put the ink to the board because of undercutting 
  of light, 
  > however i have made
  > a few boards the wrong way around and it always worked...
  > it should not affect the result in larger copper areas (e.g. a 
  pad).
  > 
  > ST

  Although it may not make a differance I fliped the film over, so the 
  ink faced the board.
  My original trial board was exposed for 4 to 13 mins at 1 min 
  intervals, now I tried exposing another board for 12 to 30 mins in 2 
  min steps.
  Still not developing, should I see an image of the transfer (even a 
  faint image) before developing the board ?
  One thing that may be worth mentioning is that for this second trial 
  I used the same deveoping solution that I used for the first (is it 
  normal to do this or should I have made anew batch for each 
  development)..?
  The original board had an image for few seconds then seem to 
  dissapear in the solution, this new board exposed for longer had no 
  such image. Could it be I need to expose for a much shorter time <4 
  mins ?

  Kind Regards 

  Tbone



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

Thanks for the idea of measuring the powder, I hadn't thought of 
that way to do it.
Adam wrote:-
"Before worrying about exposure times, try as I said before, and 
expose a
piece of PCB in the sun for 20+ minutes, put some black PVC tape on 
one
half to block out the light. Then you have guaranteed exposure. 
Develope
the PCB and see how it goes."
I live in the uk and at the moment the weather is rain and them some 
more rain, so the chance of sun is very slim.

I did however try exposing a peice of board for only 2 mins and 
another at 1hr 10 mins but with no image showing on the board before 
developing as stated by Stefan:-

"with the boards i used one could see a yellow/green discoloration
if you hold it at an agle against the light."
and Leon
"There should be a faint image visible if the exposure was OK"

So Now I have tried boards without film and with film for the 
following times
2,4,5,6,7,8,9,10,11,12,13,14,16,18,20,22,24,26,28,30 and 1hr 10 mins.
 I get no colour change what so ever to the board.
So with this in mind I think:-
a/ The problem may be that I am using Phillips TL 8W / 08 F8 T5 /BLB 
blacklight tubes and not pcb exposure tubes (which are now back in 
stock). Maybe these tubes do not produce the uv required to expose 
the board or 
b/ the glass is stopping the uv from passing to to the board (this 
was salvaged from a
cheap photoframe)
To eliminate the possibility of the uv being stopped by the glass I
secured the film to the board, placed it in the bottom of the
exposure unit under the uv tubes and exposed for 14 mins.

Still get no image , thinking the presensitized board is faulty
allthough it looks the same as some other board I purchased from a
seperate source at a different time.

anybody use this "fotoboard 2" make before (available from maplin in 
the uk)

Getting desperate

Tbone

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

From: "tboneuk_2000" <a_reynolds@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, February 05, 2004 12:28 AM
Subject: [Homebrew_PCBs] Re: Dissapearing Tracks in deveoper


> To eliminate the possibility of the uv being stopped by the glass I
> secured the film to the board, placed it in the bottom of the
> exposure unit under the uv tubes and exposed for 14 mins.
>
> Still get no image , thinking the presensitized board is faulty
> allthough it looks the same as some other board I purchased from a
> seperate source at a different time.
>
> anybody use this "fotoboard 2" make before

I use it all the time without any problems.

Ordinary glass is OK with the long-wave UV used for PCB exposure. I use a 13
minute exposure, but have quite a large distance from the tubes. Your
exposure should be much less.


Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" 
<leon_heller@h...> wrote:

 
> I use it all the time without any problems.
> 
> Ordinary glass is OK with the long-wave UV used for PCB exposure. 
I use a 13
> minute exposure, but have quite a large distance from the tubes. 
Your
> exposure should be much less.
> 
> 

Heelo you wonderfull people

I am pleased to anounce that I have had sucess, a fully exposed, 
developed and etched board.

To all those people who said less exposure time .. you were right.

You see I have made many boards before on proffesinal equipment but 
never with my own home made gear. I never had to work out exposure 
times, development times etc.. they were allways known by someone 
and using a "made from bits and peices laying around the house" 
exposure unit I could not be sure of times for exposure, I naturaly 
assumed by using blacklights it would take a lot longer and 
devlopment would be slow with hobby type chemicals.

Amazingly the exposure time was about 1 min

Development a staggering 30-45 seconds

Etching about 20 mins at 20°C no bubbles just swishing the solution 
over the board.

Maybe these chemicals/boards are far better than the ones I have 
used before (it has been over 10 years). 

Thankyou all for your help, I do appreciate it and thanks for your 
patience with a newbie.

At least someone else may in the future benifit from my experience 
while searching through this forum, and more importanly benifit from 
the good people that submit helpfull advice to others

Kind Regards

Tbone

> put in the developer a unexposured pcb, it may not disolve the 
resist 
> if it dos its to strong 
> I think your to short in exposure time or maybe lights to far away-
> 3 to 4" is normal distance
> And be shore that the daylight must be tempered a bit 
 
Would not think it is too short exposure time if all the resist is 
coming off when developed.  

Sounds more like his image and the transparency is not dark enough 
or he is getting the board exposed to light before transparency is 
in place or after exposure and before going into the developer.  
These should be the only reason for all the resist to be removed in 
the developer or that the developer is for some reason way too 
strong.  His exposure time should be OK.

Ben

> I have just looked at the film I used and discovered the print 
may 
> have been the wrong way around. I presume the ink should have been 
> next to the board, I had this the other way around so the light 
hit 


Yes the printed side should be towards the board, if you had it the 
other way your image would be reversed also from how you designed if 
unless you reversed printed you transparency.  Even with the 
transparency backwards you should still get your traces just might 
be smaller in size unless you are doing really small traces.

Ben

> One thing that may be worth mentioning is that for this second 
trial 
> I used the same deveoping solution that I used for the first (is 
it 
> normal to do this or should I have made anew batch for each 
> development)..?
> The original board had an image for few seconds then seem to 
> dissapear in the solution, this new board exposed for longer had 
no 
> such image. Could it be I need to expose for a much shorter time 
<4 
> mins ?
 

If you are doing Pos. type resist???? and it is all coming off in 
developing then it is getting exposed otherwise it would not be 
coming off in developing solution.  Normally you can do a number of 
boards in the same batch of solution.  But if you solution mix is 
wrong it is not going to work.

Is there any chance that you are letting the board be exposed to 
light before you place the transparency or after exposure before 
placing in the developer???

Ben

> a/ The problem may be that I am using Phillips TL 8W / 08 F8 
T5 /BLB 
> blacklight tubes and not pcb exposure tubes (which are now back in 
> stock). Maybe these tubes do not produce the uv required to expose 
> the board or 
> b/ the glass is stopping the uv from passing to to the board (this 
> was salvaged from a
> cheap photoframe)
 
I use 15 watt blacklight tubes, they work fine, normally expose 
about 5 mins.

> Amazingly the exposure time was about 1 min
> 
> Development a staggering 30-45 seconds
> 
> Etching about 20 mins at 20°C no bubbles just swishing the 
solution 
> over the board.
> 
> Maybe these chemicals/boards are far better than the ones I have 
> used before (it has been over 10 years). 
 

Did a search for fotoboard since I was not familar with it.  Seems 
to be a UK product and I am in the USA.  Found a site that said it 
only required a 1 min exposure time which is what you have found it 
to be.  Also said that the boards supplied to schools has a 3 min. 
exposure time and that developer was half strength also.

Even with some over exposure unles your image is not dark enough you 
should have still be getting something left but then sounded like 
you developing solution may have been too strong at first also.

Anyway sounds like you found the right combination now.  

Ben

Hi All

Am I missing something here? surely if the print is turned over then one way or the other the 
circuit will be wrong.

Regards Alan

To:             	Homebrew_PCBs@yahoogroups.com
From:           	"tboneuk_2000" <a_reynolds@...>
Date sent:      	Wed, 04 Feb 2004 21:21:44 -0000
Subject:        	[Homebrew_PCBs] Re: Dissapearing Tracks in deveoper
Send reply to:  	Homebrew_PCBs@yahoogroups.com

> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
> <stefan_trethan@g...> wrote:
> > On Wed, 04 Feb 2004 17:06:49 -0000, tboneuk_2000 
> > <a_reynolds@b...> wrote:
> > 
> > > I have just looked at the film I used and discovered the print 
> may
> > > have been the wrong way around. I presume the ink should have 
> been
> > > next to the board, I had this the other way around so the light 
> hit
> > > the ink printed on the film then had to pass through the 
> transparent
> > > film itself before hitting the board.
> > > Am I right in thinking this would effect the exposure 
> efficientcy or
> > > will it not make any difference?
> > >
> > >  Kind regards
> > >
> > >  Tbone
> > >
> > >
> > 
> > it is better to put the ink to the board because of undercutting 
> of light, 
> > however i have made
> > a few boards the wrong way around and it always worked...
> > it should not affect the result in larger copper areas (e.g. a 
> pad).
> > 
> > ST
> 
> Although it may not make a differance I fliped the film over, so the 
> ink faced the board.
> My original trial board was exposed for 4 to 13 mins at 1 min 
> intervals, now I tried exposing another board for 12 to 30 mins in 2 
> min steps.
> Still not developing, should I see an image of the transfer (even a 
> faint image) before developing the board ?
> One thing that may be worth mentioning is that for this second trial 
> I used the same deveoping solution that I used for the first (is it 
> normal to do this or should I have made anew batch for each 
> development)..?
> The original board had an image for few seconds then seem to 
> dissapear in the solution, this new board exposed for longer had no 
> such image. Could it be I need to expose for a much shorter time <4 
> mins ?
> 
> Kind Regards 
> 
> Tbone
> 
> 
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>

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

From: <alan.metcaf@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, February 05, 2004 9:52 AM
Subject: Re: [Homebrew_PCBs] Re: Dissapearing Tracks in deveoper


> Hi All
>
> Am I missing something here? surely if the print is turned over then one
way or the other the
> circuit will be wrong.

He was doing this when trying to get the process to work, not for making a
real board.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

On Thu, 05 Feb 2004 09:52:41 -0000, <alan.metcaf@...> wrote:

> Hi All
>
> Am I missing something here? surely if the print is turned over then one 
> way or the other the
> circuit will be wrong.
>
> Regards Alan
>

Not if you print it mirrored.

ST