Homebrew PCBs

Hi,

I'm looking to try out photo etching and am considering the options.

Can someone please recommend a UV lighting source which:
 - is cheap
 - has consistent UV output
 - is readily available, or easily made up from items from general
   hardware stores
 - gives good results with low exposure time (preferably 5-10 mins,
   I'm not keen on 30 minutes)

Also, is it hard to get good results using spray-on resist? Should I
just cop the extra cost of pre-coated PCBs?

Cheers
David

I just use an F15T8 bulb in a standard 18" strip light fixture.  Wood pieces on both ends make it 4.5" above the surface.  I put a bent piece of aluminum (like a cookie sheet) directly over the bulb as a reflector.  It actually hangs on the buld.   Exposure time is 13 minutes with Injectoral pre-sensitized boards.  

John

  ----- Original Message ----- 
  From: David McNab 
  To: Homebrew_PCBs@yahoogroups.com 
  Sent: Friday, February 23, 2007 5:31 PM
  Subject: [Homebrew_PCBs] cheap UV light sources?


  Hi,

  I'm looking to try out photo etching and am considering the options.

  Can someone please recommend a UV lighting source which:
  - is cheap
  - has consistent UV output
  - is readily available, or easily made up from items from general
  hardware stores
  - gives good results with low exposure time (preferably 5-10 mins,
  I'm not keen on 30 minutes)

  Also, is it hard to get good results using spray-on resist? Should I
  just cop the extra cost of pre-coated PCBs?

  Cheers
  David



   

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

David McNab wrote:
> Hi,
> 
> I'm looking to try out photo etching and am considering the options.
> 
> Can someone please recommend a UV lighting source which:
>  - is cheap
>  - has consistent UV output
>  - is readily available, or easily made up from items from general
>    hardware stores
>  - gives good results with low exposure time (preferably 5-10 mins,
>    I'm not keen on 30 minutes)

Bunnings sell a helical dark blue (Woods glass) fluro tube that screws
into a normal light socket. Rig up six of them. (I haven't tried these).

> Also, is it hard to get good results using spray-on resist?

Yes. With 4 "small" flouro tubes about 50-100mm from the pcb, PRP takes
about 3-5mins IIRC.

 > Should I
> just cop the extra cost of pre-coated PCBs?

To make PRP work well means cleaning the PCB well before coating it.

Precoated PCB is less hassle to prepare, but more expen$ive from retail
shops. I get mine much cheaper from the pcb house i use.

The normal precoated pcb from the board house is 100x more sensitive
to uv light, so exposure time in normal uv light boxes may be ridiculously
short.

Sunlight.

Short wavelength UV doesn't pass through glass very well.  The good UV 
bulbs are made of quartz, hence they're kinda pricey.

I've done boards in sunlight with some success.  The trouble is, the 
amount of UV you get from the sun varies widely from day to day and I 
think humidity eats it up.

Russell Shaw wrote:

> David McNab wrote:
>   
>> Hi,
>>
>> I'm looking to try out photo etching and am considering the options.
>>
>> Can someone please recommend a UV lighting source which:
>>  - is cheap
>>  - has consistent UV output
>>  - is readily available, or easily made up from items from general
>>    hardware stores
>>  - gives good results with low exposure time (preferably 5-10 mins,
>>    I'm not keen on 30 minutes)
>>     
>
> Bunnings sell a helical dark blue (Woods glass) fluro tube that screws
> into a normal light socket. Rig up six of them. (I haven't tried these).
>
>   
>> Also, is it hard to get good results using spray-on resist?
>>     
>
> Yes. With 4 "small" flouro tubes about 50-100mm from the pcb, PRP takes
> about 3-5mins IIRC.
>
>  > Should I
>   
>> just cop the extra cost of pre-coated PCBs?
>>     
>
> To make PRP work well means cleaning the PCB well before coating it.
>
> Precoated PCB is less hassle to prepare, but more expen$ive from retail
> shops. I get mine much cheaper from the pcb house i use.
>
> The normal precoated pcb from the board house is 100x more sensitive
> to uv light, so exposure time in normal uv light boxes may be ridiculously
> short.
>
>

Hello Dale,

  Saturday, February 24, 2007, 5:10:28 AM, you wrote:

> Sunlight.

  Nonconstant UV-A radiation on hourly basis.

> Short wavelength UV doesn't pass through glass very well.  The good UV 
> bulbs are made of quartz, hence they're kinda pricey.

  Short  UV  has  nothing  to  do with photoresist on copperclad. Peak
  sensitivity of photoresist is somewhere around 340nm what stands for
  'long wave UV' aka UV-A.

> I've done boards in sunlight with some success.  The trouble is, the 
> amount of UV you get from the sun varies widely from day to day and I 
> think humidity eats it up.

  For  my  prototypes I use Philips UV tubes for reprography. they are
  marked  'somethinginhere/05N'.  Won't  harm  your  eyes,  and  this
  wavelength  of  UV  is  passing ordinary window glass. I'm using 6mm
  (1/4")  piece  as  it  is heavy enough to make enough pressure to my
  repro films or vellum.

-- 
 Best regards,
 Zoran A. Scepanovic
 zastos@...

*********
When working toward the solution of a problem, it always helps if you know the answer. 
*********

Please be advised what was said may be absolutely wrong, 
and hereby this disclaimer follows.  
I reserve the right to be wrong and admit it in front of the entire world.



Local time: 08:31


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

Very Good light source here:
http://thinktink.com/stack/volumes/voliii/equipment/uvlamp/uvlamp.htm

I use presensitized pcb, brand name Ever-Muse
takes 90 - 120 sec for good exposure.
bob

On Sat, 2007-02-24 at 06:32 -0700, Robert Blumer wrote:
> Very Good light source here:
> http://thinktink.com/stack/volumes/voliii/equipment/uvlamp/uvlamp.htm

Thanks

> I use presensitized pcb, brand name Ever-Muse
> takes 90 - 120 sec for good exposure.

Now that's what we want - an exposure phase in less than the time it
takes to run board+artwork n times through a laminator :)

The idea of a 10-30 minute exposure was putting me off photo in a big
way.

Cheers
David

>The idea of a 10-30 minute exposure was putting me off photo in a big
>way.

This homebrew light box takes 3.5 minutes per side to expose double 
sided 6"X4" Ever-Muse boards and that's with normal daylight 
fluorescent bulbs. The single sided Ever-Muse boards are much more 
sensitive, it only takes 90 seconds. I have UV tubes for the box but 
never got around to using them since the box is much more useful as a 
portable light source.

http://www.pbase.com/eldata/image/52321530

--- In Homebrew_PCBs@yahoogroups.com, David McNab <rebirth@...> wrote:
>

I use a 500 watt halogen "work light" from the hardware store, $10 
including an extra bulb stashed in the handle. I also use this chinese 
dry-film resist (ebay, $40 for way more than I can use before it dies) 
fed through a $25 laminator from walmart, using the procedures noted at 
thinktink.com. My contact frame is an old glass-faced photo contact 
printer, a couple bucks at a thrift store but generally available cheap 
on fleabay.

With the UV-filtering glass and guard assembly flopped out of the way I 
get a good exposure in about four minutes at ~18 inches. I also avoid 
eyeball exposure, I figure that UV filter is there for a reason.

I generally only do brass, not copper pcb, and I have a darkroom so I can 
go from a good dark inkjet print to litho film without too terrible much 
trouble. I *have* used an inkjet print as the mask (oil the paper with 
vegetable oil, let soak a while, then keep wiping until dry-ish), takes 
about twice the exposure and requires testing - produces slightly rough 
edges. I'm going to need to make a pcb or two soon, so I expect this 
experience will come in handy.

     -Gary

>  Can someone please recommend a UV lighting source which:
>  - is cheap
>  - has consistent UV output
>  - is readily available, or easily made up from items from general
>  hardware stores
>  - gives good results with low exposure time (preferably 5-10 mins,
>  I'm not keen on 30 minutes)

Can you describe what makes brass pcb different from copper pcb? I'm wondering if I should switch to brass material.
How good is soldering?

regards -
Henry

www.ehydra.dyndns.info


-----Urspr\ufffdngliche Nachricht----- 
Von: "garydeal" <garydeal@...>
An: <Homebrew_PCBs@yahoogroups.com>
Gesendet: Dienstag, 27. Februar 2007 11:48
Betreff: [Homebrew_PCBs] Re: cheap UV light sources?


| I use a 500 watt halogen "work light" from the hardware store, $10
| including an extra bulb stashed in the handle. I also use this chinese
| dry-film resist (ebay, $40 for way more than I can use before it dies)
| fed through a $25 laminator from walmart, using the procedures noted at
| thinktink.com. My contact frame is an old glass-faced photo contact
| printer, a couple bucks at a thrift store but generally available cheap
| on fleabay.
|
| With the UV-filtering glass and guard assembly flopped out of the way I
| get a good exposure in about four minutes at ~18 inches. I also avoid
| eyeball exposure, I figure that UV filter is there for a reason.
|
| I generally only do brass, not copper pcb, and I have a darkroom so I can
| go from a good dark inkjet print to litho film without too terrible much
| trouble. I *have* used an inkjet print as the mask (oil the paper with
| vegetable oil, let soak a while, then keep wiping until dry-ish), takes
| about twice the exposure and requires testing - produces slightly rough
| edges. I'm going to need to make a pcb or two soon, so I expect this
| experience will come in handy.
|
|      -Gary
|
| >  Can someone please recommend a UV lighting source which:
| >  - is cheap
| >  - has consistent UV output
| >  - is readily available, or easily made up from items from general
| >  hardware stores
| >  - gives good results with low exposure time (preferably 5-10 mins,
| >  I'm not keen on 30 minutes)
|
|
|
| Be sure to visit the group home and check for new Links, Files, and Photos:
| http://groups.yahoo.com/group/Homebrew_PCBs
|
| If Files or Photos are running short of space, post them here:
| http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
| Yahoo! Groups Links
|
|
|

At 7:11 am ((PST)) Thu Mar 1, 2007, otc_friend wrote:
>Can you describe what makes brass pcb different from copper pcb?

Yes: AFAIK there isn't any!

(You have misinterpreted 'brass' as an adjective instead
of a noun in order to extend its scope to 'pcb'.)

Brass pcb wouldn't work all that well commercially since
the zinc content might mess up the processing baths,
would mess up the solder chemistry, and brass is a
much poorer electrical conductor than copper.

Some contributors here use (photo)chemical etching to
make parts out of metal shim stock; for example stencils,
and chassis frames for model railway rolling stock.

It produces a high-precision result in material which is
too fragile for mechanical machining, without the
expensive machinery of EDM or ECM.


Regards, LenW

Personally I found soldering brass metal not very difficult. I mean here low-temperature soldering, not plunging.
So it may make sense to ask for use it as a pcb material. Especially if the board should be thick and stable.
I think "German silver" would be another material especially for model builders.

Thank you for your explanation!

regards -
Henry


www.ehydra.dyndns.info


-----Urspr\ufffdngliche Nachricht----- 
Von: "Len Warner" <novost@...>
An: <Homebrew_PCBs@yahoogroups.com>
Gesendet: Freitag, 2. M\ufffdrz 2007 13:52
Betreff: [Homebrew_PCBs] Re: cheap UV light sources?


| At 7:11 am ((PST)) Thu Mar 1, 2007, otc_friend wrote:
| >Can you describe what makes brass pcb different from copper pcb?
|
| Yes: AFAIK there isn't any!
|
| (You have misinterpreted 'brass' as an adjective instead
| of a noun in order to extend its scope to 'pcb'.)
|
| Brass pcb wouldn't work all that well commercially since
| the zinc content might mess up the processing baths,
| would mess up the solder chemistry, and brass is a
| much poorer electrical conductor than copper.
|
| Some contributors here use (photo)chemical etching to
| make parts out of metal shim stock; for example stencils,
| and chassis frames for model railway rolling stock.
|
| It produces a high-precision result in material which is
| too fragile for mechanical machining, without the
| expensive machinery of EDM or ECM.
|
|
| Regards, LenW

>Can you describe what makes brass pcb different from copper pcb? I'm 
>wondering if I should switch to brass material.
>How good is soldering?

     I'm sorry, I meant that I etch brass sheet, not pcb's (mostly, 
anyway). The brass sheet is for parts for miniaturists and the whole 
etching thing was more of an exercise in learning another process for 
making prototypes for my job (making things for miniaturists). I joined 
here more for the etching info, but I've learned plenty about doing 
pcb's. 

     I need to make a small pcb soon, I expect the 1 oz or so copper will 
be easier to etch than the .010" brass I did last.

     -Gary

There is no such thing as a brass pcb.

People etch thin sheets of brass for making models.  For example:
http://www.etched-brass.scale-train.com/EBNFARMWINDMILL_windmill-3.php

-Sebastien Bailard
RepRap.org - self-reproducing 3D printer project

On Thursday 01 March 2007 09:47, otc_friend wrote:
> Can you describe what makes brass pcb different from copper pcb? I'm
> wondering if I should switch to brass material. How good is soldering?
>
> regards -
> Henry
>
> www.ehydra.dyndns.info
>
>
> -----Ursprüngliche Nachricht-----
> Von: "garydeal" <garydeal@...>
> An: <Homebrew_PCBs@yahoogroups.com>
> Gesendet: Dienstag, 27. Februar 2007 11:48
> Betreff: [Homebrew_PCBs] Re: cheap UV light sources?
>
> | I use a 500 watt halogen "work light" from the hardware store, $10
> | including an extra bulb stashed in the handle. I also use this chinese
> | dry-film resist (ebay, $40 for way more than I can use before it dies)
> | fed through a $25 laminator from walmart, using the procedures noted at
> | thinktink.com. My contact frame is an old glass-faced photo contact
> | printer, a couple bucks at a thrift store but generally available cheap
> | on fleabay.
> |
> | With the UV-filtering glass and guard assembly flopped out of the way I
> | get a good exposure in about four minutes at ~18 inches. I also avoid
> | eyeball exposure, I figure that UV filter is there for a reason.
> |
> | I generally only do brass, not copper pcb, and I have a darkroom so I can
> | go from a good dark inkjet print to litho film without too terrible much
> | trouble. I *have* used an inkjet print as the mask (oil the paper with
> | vegetable oil, let soak a while, then keep wiping until dry-ish), takes
> | about twice the exposure and requires testing - produces slightly rough
> | edges. I'm going to need to make a pcb or two soon, so I expect this
> | experience will come in handy.
> |
> |      -Gary
> |
> | >  Can someone please recommend a UV lighting source which:
> | >  - is cheap
> | >  - has consistent UV output
> | >  - is readily available, or easily made up from items from general
> | >  hardware stores
> | >  - gives good results with low exposure time (preferably 5-10 mins,
> | >  I'm not keen on 30 minutes)
> |
> | Be sure to visit the group home and check for new Links, Files, and
> | Photos: http://groups.yahoo.com/group/Homebrew_PCBs
> |
> | If Files or Photos are running short of space, post them here:
> | http://groups.yahoo.com/group/Homebrew_PCBs_Archives/
> | Yahoo! Groups Links

You can make your own brass pcb. I see no problem as such.

- Henry


www.ehydra.dyndns.info


-----Urspr\ufffdngliche Nachricht----- 
Von: "Sebastien Bailard" <penguin@...>
An: <Homebrew_PCBs@yahoogroups.com>
Gesendet: Dienstag, 6. M\ufffdrz 2007 03:14
Betreff: Re: [Homebrew_PCBs] Re: cheap UV light sources?


There is no such thing as a brass pcb.

People etch thin sheets of brass for making models.  For example:
http://www.etched-brass.scale-train.com/EBNFARMWINDMILL_windmill-3.php

-Sebastien Bailard
RepRap.org - self-reproducing 3D printer project

On Thursday 01 March 2007 09:47, otc_friend wrote:
> Can you describe what makes brass pcb different from copper pcb? I'm
> wondering if I should switch to brass material. How good is soldering?
>
> regards -
> Henry
>
> www.ehydra.dyndns.info
>

On Wed, 07 Mar 2007 18:54:56 +0100, otc_friend <otc_friend@...> wrote:

> You can make your own brass pcb. I see no problem as such.
> - Henry


They do aluminum layers now, for heatsinks.

ST