What is foaming stuff on some parts on pwr board?

[pixelphoto]

I've just replaced some caps in my monitor and there is a white firm but spongy substance affixed to a number of parts. It was necessary to use a xacto blade to slice through several to enable the removal of 3 caps. Is it there to reduce resonance and vibration? What is it? Is it that foaming stuff used in electrical outlets as insulation. Is there a substitute? Is it necessary to replace it?

Thanks,
Cheers, Marvin

[Evil Lurker]

Re: What is foaming stuff on some parts on pwr board?

That be glue. Manufacturers use it to secure components to the PCB before soldering them in place. Saves time and money for the manufacturer, bad for the consumer as some types of glue used have a tendency to degrade over time and become electrically conductive. Unless its a silicon type adhesive, it needs to go!

[pixelphoto]

Re: What is foaming stuff on some parts on pwr board?

Holly cow Evil Lurker that was as fast as a speeding bullet! Thanks for the response. I'll be going back in tomorrow to replace more caps so I'll just slice it off.


Regards,
Marvin

[ratdude747]

Re: What is foaming stuff on some parts on pwr board?

yeah

the general rule (IIRC):

if it is white or clear, it is ok (cut it if you need to, obviously). the white is silicone (often seen in higher end units, often delta and olderish hipro), the clear is traditional hot glue (normally found in cheap PSUs, leadman/powmax units come to mind).

if it is yellow, brown, or black, get rid of it! this is the type that turns conductive. not sure on the chemical type... as it turns from yellow to brown to black, it becomes more and more conductive. seen in many brands, including bestec, ultra, and enermax among others.