is arctic silver unacceptable for the BIP373??

[icarus]

ok i have another thread that details my megasquirt troubles here:

http://forums.hybridz.org/showthread.php?t=136325

 

but i have a specific question here that has arisen from stumbling across this post on a random other forum:

 

2nd issue with the BIP and the heatsink. I'm going to blame myself for that as well. I had a tube of heatsink compound from my computer laying around(silver based stuff). It is more conductive then the thermal compound that comes with the megasquirt chips. Later today, I'm going to remount the BIP with new compound and double check all the resistances. Once that is set everything should be good.

the BIP373 has a metal backing and must therefore be insulated from the heatsink to avoid grounding it out, a mica plate is used but is the silver-based heatsink compound conducting and grounding it out?

 

is this plausible? could this really be the cause of all of my trouble not getting spark out of my MS running the Bosch BIP373 direct coil driver??

 

i just used a tube of heatsink compound that i had laying around from my last computer build, thinking it would suffice,

here is what i used:

 

 

i guess it would be nice if this was what was causing all my headache...

[m4xwellmurd3r]

that's possible I suppose. if the chip does indeed need to be insulated from the heatsink, arctic silver would conduct electricity. If you do want to use some sort of computer heatsink compound, I suggest using Arctic Silver Ceramique. for PC applications, there's only a 2-3C difference in temps compared to arctic silver 5.

[icarus]

that wasnt the problem for me unfortunately

 

but for others' purposes i guess ill say that this HAS been the case for some with the Bosch BIP373. it can apparently be EXTREMELY sensitive to being accidentally grounded to the heatsink. so make sure to insulate it thoroughly.

 

 

here is what i did to test, i unscrewed the BP from the heatsink and bent it upward so that it was not at all contacting anything, and mine still isnt sparking for me, so this wasnt my problem i guess:

 

 

on to try other things i suppose...

[Matt Cramer]

You're not the first. I've seen times where the heat sink compound - even the white stuff we use on our assembled units - got around the mica and grounded out a BIP373.

[icarus]

as you can probably see in the picture, i applied... well, liberally

 

gonna get a non-conductive compound (like ceramique) and use a VERY small quantity to avoid any squishing around the edges at all.

[FricFrac]

Old thread but important to note for those coming back here for info - if you are concerned about the device not being isolated from the heat sink do a simple resistance check with your ohm meter - should read very high (as in not conducting). Also remember less is more with thermal compound. Its there to fill in the microscopic scratches and flaws in the finish of the metals. There shouldn't really be any "squishing out" of the thermal compound. I do put it on both sides of the mica myself though - just very thin. If normal thermal compound isn't doing the job you need to make sure your mechanical connection is good otherwise you need a better heat sink not a better thermal paste.