Newbie- Mounting the PCB directly to a heatsink for better heat transfer?

[Hirudin]

Howdy Mariss,

I was looking at my G340 drives and being the curious person I am I started removing screws. There are 2 screws that hold the PCBs to the base. If you remove those screws the PCBs and base will separate revealing 5 MOSFETs (I'm pretty sure that's what they're called) with heatsink compound on them.

Being a computer nerd what I see when I do this is the potential for achieving better heat transfer by removing the base and screwing the PCB directly to the heatsinks. I figure this will also reduce the amount of heatsink compound I need to use as the base is quite large.

I'm not sure if there was a warranty on this drive to start with, but I figure since I bought it used (they say "G7" on top so I think that means they were shipped July '07 originally) it was probably already void before I got it. So I'm not worried about that.

Do the MOSFETs need to be electrically isolated from each other? I plan to attach several drivers/heatsinks together, is it necessary to keep the MOSFETs from different drivers electrically isolated?

I did my best to measure between the screws, I came up with ~0.955" (or ~24.25mm) center to center. Is there some place where I can find the exact measurement? Or, can you please look it up for me?

If someone at Gecko is looking up dimensions, would it be possible to also get the exact distances from the edges of the PCB so that it can be mounted perfectly centered?

Thanks!

[CoAMarcus]

The MOSFETs must be isolated. That plate they are attached to is a hard anodized aluminum plate. The dimensions for the plate are on the last page of the G340 manual, which is what you will want to mount to your heatsink. If it is not attached to the hard anodized plate it is currently on and is instead put on a piece of conductive metal, the MOSFETs will be destroyed on power up.

Marcus

[Hirudin]

Aw darn... Yeah, the heatsinks I got are copper based, so definitely conductive. I really like the idea of mounting directly to the heatsink though. Maybe I'll throw a electrically isolating/heat conductive pad on there instead... we'll see. Thanks for letting me know what needs to be done!

If you come across those screw-hole dimensions and feel like sharing them please do!