How best to make connection mosfet to fat wire ?

You need to get a piece of copper clad circuit board. Then, use a Dremel with a fine bit or cutting wheel and remove enough copper so that you have the two or three pads (per fet) necessary to solder your fets to, and leave enough copper to solder heavy wires to. You could even drill holes to route the wires through to give it additional mechanical support.

I think Radio Shack still carries this type of board. Is there a Frys near you?

Bob

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Thanks for the answer

I had thought about something like that, but was concerned that the circuit board thickness might not carry the current.. I guess id have to look for a fairly thick copper coating.

"Ray"

** Only the source lead needs to have a large area pad - and you can make it as big as you like as that lead is on one side.

The common drain connector is the heatsink

Running solder all over the pad and drain lead reduces resistance to a trivial amount.

.... Phil

In the original post, it sounds like you mostly have a stress-relief problem.

Instead of copper-clad circuit board, just use perf-board. Enlarge holes as needed for the

14-gage wire, a short distance from the holes you are using for the FET leads. Push the FET leads and wire through the board from the top, solder on the bottom. You may be able to bend over the FET leads to wrap around the wire ends, or vice-versa, or use separate hookup wire between them.

If this doesn't give enough stress relief, take steps to "nail down" the wire before it goes through the hole. Run it parallel to the board (so it turns 90 degrees to go through the hole), and either hot-glue to the board, or use a short piece of hookup wire to lace it down through other holes. Or both.

You can sometimes avoid the perf-board completely by assembling and soldering while held in a little "helping hands" (alligator clip, etc) clamp, then applying hot glue and letting it solidify before releasing the clamps. You end up with a "glob on a wire", which can then be screwed to a heat sink, etc.

Best regards,

Bob Masta DAQARTA v4.51 Data AcQuisition And Real-Time Analysis

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**Thanks for the idea's Guys....

Should be able to a better job on the next try

M

the mosfets which are

Mount one or more standoffs to the heatsink, and run the heavy wire to the standoff(s); if you can't find something easier to connect, a barrier strip terminal array is suitable.

From the terminals on the MOSFETs, run copper braid (like the outside of a coax cable, it's available in many sizes, pre-tinned) to the standoff.

The first key element is that the heavy wire must be mechanically attached so it doesn't bend the MOSFET lead wires; it'll pull the leads and short them, or will pull free of a solder connection in PCB material (PCB direct to heavy wire is a VERY BAD idea). The second key element is an easily routed (flexible) wire to bring out the leads from the MOSFET, and wire-ring with braid and lead soldered inside, or braid wrapped around/soldered to the lead, or even barrel crimp over the lead, will work fine. I sometimes make lap joints, with a strand of copper wire whipped around the lap region; flux and solder, it'll hold firm.

Many hardware store carry copper flashing, you could make heavy duty fiberglass circuit board material.

You could bolt ordinary copper circuit board strips to aluminum rectangular bar stock from the hardware store to beef up the current capacity.

Just run some #8 solid wire between two insulating supports.

You can special order metal from onlinemetals.com

copper rectangular bar stock