Homebrew_PCBs

I have a 24vac timer that got soaked pretty good. Tons of corrosion
on the resistors, diodes etc. The four ICs also have smooth glassy
looking areas over some of the pins (power pins I bet), making me
think they're fried.

The traces look good though. The dielectric seems to have held up, no
evidence of burning etc. Just for the hell of it, I'm going to see if
I can clean this up and replace the ICs to see if I can get it
working again.

Question is, Whats a good method of drying out the board after
cleaning? I'll go at it with distilled water and a soft brush, then
some contact cleaner but I'm worried about water trapped in little
nooks and crannies.

Would putting it in an oven set for, say, 200F for a couple hours be
a good way? If not, what would?

Scrub the board with dish washing detergent and warm water. Then
shake off the excess water and dry the board in an oven set to
approximately 150 F to 200F. You can also dip a wet board into some
alcohol to get rid of the water and then just let the alcohol
evaporate off. If your water is really hard use a distilled final dip
before using either drying method. Both ways have worked good for me
but just watch out for the potentiometers etc. that might not like
the water!

Tom


--- In Homebrew_PCBs@yahoogroups.com, "ghidera2000
<ghidera2000@y...>" <ghidera2000@y...> wrote:

> I have a 24vac timer that got soaked pretty good. Tons of corrosion
> on the resistors, diodes etc. The four ICs also have smooth glassy
> looking areas over some of the pins (power pins I bet), making me
> think they're fried.
>
> The traces look good though. The dielectric seems to have held up,

no

> evidence of burning etc. Just for the hell of it, I'm going to see

if

> I can clean this up and replace the ICs to see if I can get it
> working again.
>
> Question is, Whats a good method of drying out the board after
> cleaning? I'll go at it with distilled water and a soft brush, then
> some contact cleaner but I'm worried about water trapped in little
> nooks and crannies.
>
> Would putting it in an oven set for, say, 200F for a couple hours

be

> a good way? If not, what would?

ghidera2000 wrote:

> The traces look good though. The dielectric seems to have held up, no
> evidence of burning etc. Just for the hell of it, I'm going to see if
> I can clean this up and replace the ICs to see if I can get it
> working again.
>
> Question is, Whats a good method of drying out the board after
> cleaning? I'll go at it with distilled water and a soft brush, then
> some contact cleaner but I'm worried about water trapped in little
> nooks and crannies.

Its pointless applying cleaner AFTER rinsing with distilled water. Cleaner
residue is the killer so you want to rinse with water last. If you have copper
oxides I'd first scrub the board with vinegar, then do what Tom suggested.
I think sodium hydroxide (a main ingredient in dishwashing detergent) will
dissolve the white powdery tin(IV) oxides that may have formed on some tin
plated component leads. Rinse under running tap, shake it dry, then get spray
bottle with distilled water or alcohol and rinse the board with it. That way no
residue should remain once dried.

Adam

adam Seychell wrote:

>
> ghidera2000 wrote:
>
>>The traces look good though. The dielectric seems to have held up, no
>>evidence of burning etc. Just for the hell of it, I'm going to see if
>>I can clean this up and replace the ICs to see if I can get it
>>working again.
>>
>>Question is, Whats a good method of drying out the board after
>>cleaning? I'll go at it with distilled water and a soft brush, then
>>some contact cleaner but I'm worried about water trapped in little
>>nooks and crannies.
>
>
> Its pointless applying cleaner AFTER rinsing with distilled water. Cleaner
> residue is the killer so you want to rinse with water last. If you have copper
> oxides I'd first scrub the board with vinegar, then do what Tom suggested.
> I think sodium hydroxide (a main ingredient in dishwashing detergent) will
> dissolve the white powdery tin(IV) oxides that may have formed on some tin
> plated component leads. Rinse under running tap, shake it dry, then get spray
> bottle with distilled water or alcohol and rinse the board with it. That way no
> residue should remain once dried.

There's an electronics detergent called 'safewash 2000' that makes soldering
really shiny, removes flux, and other residue. RS Components or Farnell have
it. Just scrub the pcb with it and some warm water using an old tooth brush.