Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- 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