Re: Discrete Mosfets/IGBTs mounting techniques ...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Mike Poulton <mpoulton-at-mtptech-dot-com> 

Tesla list Wrote:
 > Original poster: "Rajesh Seenivasan" <rajeshkvs-at-hotmail-dot-com>
<snip>
 > Because, even though the mosfets can handle 40 Amps or even higher, the PCB
 > tracks cannot handle that much current ?

For high current traces, solder a continuous bare wire of appropriate
size along the length of the trace (saturate it with solder). I have
made multi-hundred-amp PCBs with this technique, and seen it used in
commercial products includung a 2kW 12VDC inverter (200A input!). For
mosfets mounted in parallel on a heatsink, I often just use
point-to-point wiring, but in a neat and electromagnetically "correct"
fashion. Just bend each lead into a different plane -- i.e. bend all
gates back 90 degrees, all sources forward 90 degrees, and leave the
drains straight (or any other combination thereof). Solder straight
heavy copper wire or bar stock across the sets of leads (light wire
for gate drive, obviously). Make the power connections for source and
drain at opposite ends of the busses to equalize the bus impedance to
each device.
-------------------------------------------------
Mike Poulton
MTP Technologies
mpoulton-at-mtptech-dot-com
KC0LLX (70cm AM ATV, 33cm/12cm FM ATV, Omaha, NE)