PCB help and diagnose ?

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PCB help and diagnose ?

Postby hopkinwfg » Sat May 17, 2014 1:05 am

Dear PCB makers designers,

I recently got myself an old amplifier which circuit runs via two large area of PCB..
as its dark green in color and perhaps double sided PCB...

upon close inspection of the PCB I spotted two unusual sight... which near the diodes and transistor were soldered on i saw very unusual lumps/bumps which happens near the soldered areas of the PCB. its certainly not flux residue but due to my course of curiosity i then feel is with a wooden stick as its rather hard but it finally burst out spewing green colored mass ...i quickly stop it as am afraid that i may have in at course spoil the PCB or in another way causes it to erode the PCB.

i am puzzled if its a process flaw or its signs of early damage of the PCB due to extreme heat generated by electronic components ?

if i should remove the bumps/lumps and clean it with alcohol and lastly encapsulate it with PCB lacquer (silicon resin type) or epoxy over the areas ?

can anybody with good indepth of PCB experience advice me on what should be the best way to restore the PCB areas ?

thank you and i also attached the pic of the PCB with arrows pointing to the concerned matters.
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Re: PCB help and diagnose ?

Postby Sal Hernandez » Thu May 22, 2014 8:06 am

I reached out to our manufacturing team and here is the feedback I received.

1. It kinda looks like it is some “damage” to the soldermask possibly from heat along the traces that has caused the mask to bubble. If it is “spewing a green mass” it almost sounds like moisture under the mask.

2. Looks like the soldermask was damaged during a hand soldering process and probably absorbed water in post clean. The mask could be an older type with poor thermal properties compared to today’s mask.

3. it could even be flux or flux/cleaner under the mask.

Clean all the gooey mask and clean up with alcohol and then use a type of air dry epoxy to cover the area to protect it from further air contaminants. There are many solder mask touch up pens that you can use to repair the areas.
Regards,

Sal Hernandez
Software Support Engineer I
Sunstone Circuits
13626 S. Freeman Road
Mulino, OR 97042
Phone: 503-829-9108 x226
Fax: 503-829-5482
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