Homebrew PCBs

I've tweaked my UV box to even out the intensity (somewhat, not 100%
perfect but good enough).  I'm ready to actually use it now :-)  I've
got some questions about steps in the photo process that would be nice
to skip or otherwise cheat on:

* Developer/stripper chemistry - is more concentrated ok?  Not optimal
  from a cost point of view, but I'm thinking of time-between-discards
  and shelf life.

* Developer/stripper temperature - I can use warm water to mix it, but
  heating it up for use might be tricky.  Will it work at room
  temperature, albiet slower?

* Laminating - hotter OK?  My laminator doesn't have a heat setting,
  and the hot air gun is too unpredictable, so do I err on the side of
  "hotter" or is "just right" important?

* baking - 212F for 5 min after developing.  How important is this?
  How critical?  Hot air gun OK?

* bubbling/agitating developer/stripper - how much of an effect is
  this?  With the containers I have I could "swish" the boards around,
  but that's about it.

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

From: "DJ Delorie" <dj@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, June 16, 2008 3:50 AM
Subject: [Homebrew_PCBs] photomask shortcuts


>
> I've tweaked my UV box to even out the intensity (somewhat, not 100%
> perfect but good enough).  I'm ready to actually use it now :-)  I've
> got some questions about steps in the photo process that would be nice
> to skip or otherwise cheat on:
>
> * Developer/stripper chemistry - is more concentrated ok?  Not optimal
>  from a cost point of view, but I'm thinking of time-between-discards
>  and shelf life.

What are you using? It's quite critical for NaOH.


>
> * Developer/stripper temperature - I can use warm water to mix it, but
>  heating it up for use might be tricky.  Will it work at room
>  temperature,

Should be used at room temperature.

>
> * Laminating - hotter OK?  My laminator doesn't have a heat setting,
>  and the hot air gun is too unpredictable, so do I err on the side of
>  "hotter" or is "just right" important?
>
> * baking - 212F for 5 min after developing.  How important is this?
>  How critical?  Hot air gun OK?

What do  you need to laminate and bake?

>
> * bubbling/agitating developer/stripper - how much of an effect is
>  this?  With the containers I have I could "swish" the boards around,
>  but that's about it.

Just rock the container. It should take under 30s for development. I use IPA 
and a piece of kitchen towel for removing the resist.

Leon

"Leon" <leon355@...> writes:

> > * Developer/stripper chemistry - is more concentrated ok?  Not optimal
> >  from a cost point of view, but I'm thinking of time-between-discards
> >  and shelf life.
> 
> What are you using? It's quite critical for NaOH.

Whatever samples javaguy is selling - http://www.pcbhobbyist.com/

> Should be used at room temperature.
> 
> >
> > * Laminating - hotter OK?  My laminator doesn't have a heat setting,
> >  and the hot air gun is too unpredictable, so do I err on the side of
> >  "hotter" or is "just right" important?
> >
> > * baking - 212F for 5 min after developing.  How important is this?
> >  How critical?  Hot air gun OK?
> 
> What do  you need to laminate and bake?

Same film as above ;-)

> > * bubbling/agitating developer/stripper - how much of an effect is
> >  this?  With the containers I have I could "swish" the boards around,
> >  but that's about it.
> 
> Just rock the container. It should take under 30s for development. I use IPA 
> and a piece of kitchen towel for removing the resist.

It's a vertical container (like a bubble-up etch tank), so I can't
rock it.

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

From: "DJ Delorie" <dj@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, June 16, 2008 4:26 AM
Subject: Re: [Homebrew_PCBs] photomask shortcuts


>
> "Leon" <leon355@...> writes:
>
>> > * Developer/stripper chemistry - is more concentrated ok?  Not optimal
>> >  from a cost point of view, but I'm thinking of time-between-discards
>> >  and shelf life.
>>
>> What are you using? It's quite critical for NaOH.
>
> Whatever samples javaguy is selling - http://www.pcbhobbyist.com/
>
>> Should be used at room temperature.

He recommends sodium carbonate, which isn't generally used. I use about 12 
g/litre sodium hydroxide. Sodium metasilicate is popular, and has much more 
latitude than NaOH. NaOH has unlimited shelf life and can be reused. A more 
concentrated solution can be used for stripping resist.

>>
>> >
>> > * Laminating - hotter OK?  My laminator doesn't have a heat setting,
>> >  and the hot air gun is too unpredictable, so do I err on the side of
>> >  "hotter" or is "just right" important?
>> >
>> > * baking - 212F for 5 min after developing.  How important is this?
>> >  How critical?  Hot air gun OK?
>>
>> What do  you need to laminate and bake?
>
> Same film as above ;-)

I use pre-coated boards - much simpler.

>
>> > * bubbling/agitating developer/stripper - how much of an effect is
>> >  this?  With the containers I have I could "swish" the boards around,
>> >  but that's about it.
>>
>> Just rock the container. It should take under 30s for development. I use 
>> IPA
>> and a piece of kitchen towel for removing the resist.
>
> It's a vertical container (like a bubble-up etch tank), so I can't
> rock it.

Just use a small plastic food container, it's much easier and cheaper.

Leon

> * Developer/stripper chemistry - is more concentrated ok?  Not
optimal   from a cost point of view, but I'm thinking of
time-between-discards
>   and shelf life.
> 
> * Developer/stripper temperature - I can use warm water to mix it, but
>   heating it up for use might be tricky.  Will it work at room
>   temperature, albiet slower?

In the tests I have done so far, I have not used exact measurements.
For the developer I think what I used would be about 1 to 2
tablespoons for 16 ounces. All I really did was just sprinkle a little
into a shallow pan of  warm water.

Since the sodium hydroxide is just used to remove the resist, I do not
think you can use too much, but again probably a few tablespoons to 16
ounces. I used warm water.

> 
> * Laminating - hotter OK?  My laminator doesn't have a heat setting,
>   and the hot air gun is too unpredictable, so do I err on the side of
>   "hotter" or is "just right" important?

My laminator has a hi and low setting. I used the high and it worked
okay.  The high setting is also what I used for toner transfer. 

> 
> * baking - 212F for 5 min after developing.  How important is this?
>   How critical?  Hot air gun OK?

Not sure about the baking. I have not done that myself. 
> 
> * bubbling/agitating developer/stripper - how much of an effect is
>   this?  With the containers I have I could "swish" the boards around,
>   but that's about it.

When developing I just swished the boards around until the unexposed
resist dissolved away. 

When stripping I just put the board in and left it for about 5
minutes. The resist will come off in clumps. 

The datasheet for the resist is on the home page of
www.pcbhobbyist.com. They give more exact parameters for lamination,
exposure, developing and stripping. 

The direct url is http://www.pcbhobbyist.com/mm100i.pdf 

The best thing to do is just give it a try on a test board and see
what happens. That's what I did.

> >
> > "Leon" <leon355@...> writes:
> >
> >> > * Developer/stripper chemistry - is more concentrated ok?  Not
optimal
> >> >  from a cost point of view, but I'm thinking of
time-between-discards
> >> >  and shelf life.
> >>
> >> What are you using? It's quite critical for NaOH.
> >
> > Whatever samples javaguy is selling - http://www.pcbhobbyist.com/
> >
> >> Should be used at room temperature.
> 
> He recommends sodium carbonate, which isn't generally used. I use
about 12 
> g/litre sodium hydroxide. Sodium metasilicate is popular, and has
much more 
> latitude than NaOH. NaOH has unlimited shelf life and can be reused.
A more 
> concentrated solution can be used for stripping resist.


Actually the datasheet for the resist recommends that you do not use
NaOH for developing. Instead Sodium or Potassium Carbonate is
recommended.

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

From: "javaguy11111" <javaguy11111@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, June 16, 2008 5:22 AM
Subject: [Homebrew_PCBs] Re: photomask shortcuts


>> >
>> > "Leon" <leon355@...> writes:
>> >
>> >> > * Developer/stripper chemistry - is more concentrated ok?  Not
> optimal
>> >> >  from a cost point of view, but I'm thinking of
> time-between-discards
>> >> >  and shelf life.
>> >>
>> >> What are you using? It's quite critical for NaOH.
>> >
>> > Whatever samples javaguy is selling - http://www.pcbhobbyist.com/
>> >
>> >> Should be used at room temperature.
>>
>> He recommends sodium carbonate, which isn't generally used. I use
> about 12
>> g/litre sodium hydroxide. Sodium metasilicate is popular, and has
> much more
>> latitude than NaOH. NaOH has unlimited shelf life and can be reused.
> A more
>> concentrated solution can be used for stripping resist.
>
>
> Actually the datasheet for the resist recommends that you do not use
> NaOH for developing. Instead Sodium or Potassium Carbonate is
> recommended.

It must be a different resist than is used on precoated boards. Is it 
negative?

Leon

--- In Homebrew_PCBs@yahoogroups.com, "Leon" <leon355@...> wrote:
>
> ----- Original Message ----- 
> From: "javaguy11111" <javaguy11111@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Monday, June 16, 2008 5:22 AM
> Subject: [Homebrew_PCBs] Re: photomask shortcuts
> 
> 
> >> >
> >> > "Leon" <leon355@> writes:
> >> >
> >> >> > * Developer/stripper chemistry - is more concentrated ok?  Not
> > optimal
> >> >> >  from a cost point of view, but I'm thinking of
> > time-between-discards
> >> >> >  and shelf life.
> >> >>
> >> >> What are you using? It's quite critical for NaOH.
> >> >
> >> > Whatever samples javaguy is selling - http://www.pcbhobbyist.com/
> >> >
> >> >> Should be used at room temperature.
> >>
> >> He recommends sodium carbonate, which isn't generally used. I use
> > about 12
> >> g/litre sodium hydroxide. Sodium metasilicate is popular, and has
> > much more
> >> latitude than NaOH. NaOH has unlimited shelf life and can be reused.
> > A more
> >> concentrated solution can be used for stripping resist.
> >
> >
> > Actually the datasheet for the resist recommends that you do not use
> > NaOH for developing. Instead Sodium or Potassium Carbonate is
> > recommended.
> 
> It must be a different resist than is used on precoated boards. Is it 
> negative?
> 
> Leon
>
 
It is Dupont Riston. It is a dry film negative actiing resist.

hey guys.... 
did you notice that you left SIX levels of previous messages?
is that necessary to make your point?

--- On Mon, 6/16/08, javaguy11111 <javaguy11111@...> wrote:

>> >> >> > * Developer/stripper chemistry - is more concentrated ok?  Not optimal
>> >> >> >  from a cost point of view, but I'm thinking of time-between-discards and shelf life.

...

Hello,

your developer should be 9:1 ratio. 9 parts warm water to 1 part
developer. How i do it, when Im "burning" the image, I have the
developer in its tub sitting in another with hot water. That heats up
the developer just right. You dont need a bubbler in with the
developer. just swish it over the board like your doing, when the
image youve burned appears, remove board and rinse. I dont do
laminating on my boards, but I think a spray mask would work better
for you.

heres a link for the product:
http://www.soselectronic.com/?str=371&artnum=S035740

hope this helps!
Joe