On Aug 30, 8:59*pm, "Phil Allison" wrote:
** I had hoped that the dreaded Yellow Glue peril had gone away - but it is
still with us.

Most of you will have seen it holding parts down to PCBs on Asian made
equipment and many of those will have seen what happens if the parts
involved get hot.

The example on my bench is the SMPS from an Alesis powered monitor ( M1
Active, Chinese made) ) which has blown up big time because of the damn
Yellow Glue used to secure a ferrite toroidal coil. *All the glue used had
gone brown or back ( ie carbonised ) on this coil and arced across nearby
tracks taking out the main switching MOSFET, its drive IC and associated
transistors, high speed diodes and even the AC bridge rectifier diodes.

The toroidal coil had to be un-wound, cleaned up and re-wound. The same glue
was attacking parts elsewhere on the board too ( it corrodes copper) and had
to be laboriously scraped off.

Are the dickheads who squirt this horrible goop all over PCBs *NEVER *going
to wake up ??

..... *Phil

Sony had a problem with this glue on broadcast video recorders years
ago. Their tech bulletin blamed "CHLOROPRENE GLUE". One current mfr
data sheet shows a reduction in resistance from 10^13 to 10^8 after
500 hours at 100C. Unfortunately, the resistance just keeps dropping
after that.