Spot welding coper shim

By dolphin Date 11-21-2002 04:17

Dear anyone,

I would like to spot weld copper shim of thickness 70 microns to copper sheet of thickness 200 microns. the size of the weld is about 5mm square. I have tried using our little welder but unfortunately the electrode tends to stick to the shim. I was wondering if anyone would be able to advise me on what sort of electrodes (if any) could be used in our application.

I look forward to a reply,

cheers,

James Cotsell

By G.S.Crisi (****)

Date 11-22-2002 17:33

Dear James,
You're talking about thicknesses of 70 microns (0.07 millimeters) and 200 microns (0.2 millimeters). The welding current must be measured perhaps in tenths of an amps.
Here in this site, the majority of us are accostumed to currents measured in hundreds of amps and thicknesses of 1/8 of an inch (3.2 millimeters) and over.
Yours is a welding application, sure, but I doubt that anybody in this site is able to answer your question. I'd be happy to be wrong and see an answer, so I'll learn something new.
Your application is typical for making chips, semiconductors, printed circuits and other sophisticated electronic stuff. Perhaps this opinion will put you in the right direction to have your doubt cleared up.
Giovanni S. Crisi
Sao Paulo - Brazil

By jwright650 (*****)

Date 11-22-2002 18:18

James,
What process(s) have you tried? Would a soldered joint work? I would think that an electric soldering gun of sufficient wattage should do the trick.
Anyway, I have to agree with Giovanni about my knowledge of welding such thin materials, particularly copper which conducts heat so well.
I too, hope that someone will be able to answer your question, so I too, can learn alittle more myself.
John Wright

By Ratinfested Date 12-04-2002 05:06

If you explain to me a little better what your trying to do i may be able to help. You are resistance welding right? Whats the electrode tip shape and size? I weld most anything all shapes and sizes all kinds of different materials. For an example click below.
http://www.geocities.com/ratinfested/foil.html?1022125847940

By DGXL

Date 12-04-2002 17:23

dolphin:
One of my clients performs "micro-spot welding" as they call it. They are a specialty RSW company. They typically use custom electrodes of various alloys and alloyed copper. A 5mm nugget sounds kind of large for the material thickness (maybe why the shim is sticking?) in your application. I think they use their "standard" equipment with material such as yours and they use their "high-end" equipment (upslope/downslope, etc.) on the exotic stuff.

Be sure the electrode is of the correct material, tip diameter, welding parameters (hold, weld, forge, energy, etc.) and the tip is dressed properly.