Homebrew_PCBs

Hi,

I have some old PCB boards that were exposed but never eched. I
need to find something to remove the old resist. I have tried Mineral
Spirits, Lacquer Thinner, Acetone, Gasoline and nothing touches it. I
would sure appreciate any ideas. I have not been able to locate a
source for a "remover" though I know it is made. Also, is there a
source in the US for Positive Resist in spray cans? I must be
searching in the wrong place.

Thanks - Jack

Jack:

I admit I have used ONLY one kind of that "spray-on, photo-sensitive resist",
and it ALWAYS came off instantly with JUST lacquer thinner. BUT, I imagine
it may be possible that it "time-hardens", if not cleaned off within a week
(?).

I would try 50/50 Amyl Acetate (that's Laq.Thin., I THINK), and Acetone, Let
it Soak (if you don't have a shallow pan, you would have to "paint it on"
continuously, and 90% would be lost by evaporation very quickly, AND, it'd be
dangerous! DO this outdoors, if you do it at all, and wear "surgical
gloves", at least!)

Try "pushing it off" with bits of Scotchbrite, after it has soaked several
minutes to a quarter hour. It MAY be quite soft, just not "fluid", after
"aging".

Some Chemguru in here know the answer???

Jan Rowland


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

If it is dry film resists then you need a strong alkaline like sodium
hydroxide. Exposed the remaining resists and then soak in say 5%
solution for few minutes and it should just 'lift' off of copper.

jackafaz wrote:

>Hi,
>
> I have some old PCB boards that were exposed but never eched. I
>need to find something to remove the old resist. I have tried Mineral
>Spirits, Lacquer Thinner, Acetone, Gasoline and nothing touches it. I
>would sure appreciate any ideas. I have not been able to locate a
>source for a "remover" though I know it is made. Also, is there a
>source in the US for Positive Resist in spray cans? I must be
>searching in the wrong place.
>
>Thanks - Jack
>
>
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[Non-text portions of this message have been removed]

I had some exposed board that had negative kpr type resist i think i
used paint stripper to clean them it was stippeze i think the active part
was methylene chloride nasty stuff wear gloves. good luck

Adam -- I think that 5% NaOH is overdoing it -- not that Sodium
Hydroxide is expensive -- but I think that 3% is fine. 5% will blow
the photoresist right off the copper. Of course, if it's just
one-shot then mix a capful of drano with 100ml of water and let her rip.