Heavy Copper & Exotic Matl

[VMFA312]

I have a requirement for 10+ oz copper, which may exceed 150 degrees c. The brd will be compressed between aluminum & sil-pad insulators with 100+ psi. All this at 10-8 torr vacuum. Should I find a bridge to jump off???? Anyone have any experience with these kind of conditions? I'm sure open to thoughts.

[randychase]

Wow :eek:

I have done high temp 12 ounce copper boards, sounds similar. We also used aluminum bolt on heatsinks and thermal pads and grease. FETs up the wazoo to deal with a lot of power.

(side note. One company I laid out boards for did very high power stuff. They needed a "load" so they got this huge cable and coiled thousands of feet of it on their roof as a load. When the powered it up, it worked well, but a little while later, they received a visit from San Diego Gas and Electric wanting to know the source of the huge power drain)


The bridge may be the best choice. I can tell you hint, that at 12 ounces, the etchback is significant and you do not want to use really fine traces and pads. If there is mixed technology on the board, I recommend splitting it up. Do not put the controller circuit on the same board.

[VMFA312]

Thanks,
I understand the etch back issue. Can you tell me what the track/space you used? I'm trying to get the thermal pours as close as possible without the brd fab guys hunting me down.

[randychase]

It's been a while, but I think we designed the boards with a min .020" track and spacing.

[VMFA312]

Thanks,
I'm going for 15/17 on 10oz. I'll post results & notes after testing.

[robert Tarzwell]

yes you can get 10 oz boards made, your design sounds like one i made for Boeing
there are design guidlines available from Colins /rockwell, and others. I have writen 2 books on the subject of heavy copper and high voltage printed circuit design and manufacturing. and are available at megadawn.com not all heavy copper circuits are only etched, in fact most are not, but rather plated up with a combination of 4 oz base copper and plating up to 10 oz, we easly produced 10 oz boards with .030 mill traces and spaces with almost no etch back. It is also possible to make boards with diffrent levels of copper , this allows for heavy copper (10oz) traces for the power and thin ( 2 oz ) traces/pads for the SMT components.
you can also get the traces buried withing te boards so the solder mask and white marking are not over high traces. If any one needs help on heavy copper they can contact me through this forum. rtarzwell