SPOT WELDER FOR MAKING SMALL ELECTRICAL CONTACTS

A capacitive-discharge spot welder is described which is primarily int ended for making electrical connections between small (<25-150 mu m di ameter) wires and samples of metallic materials, although it can be us ed in many applications where miniature welds must be made. It has bee n particularly useful in allowing low resistance (several m Omega) con tacts to be created on samples of rare earth and actinide intermetalli c compounds which are highly resistant to soldering. The device has a minimum time constant of about 25 mu s and can deliver a maximum of be tween 700 mu J and 400 mi of energy to the weld legion, depending on t he resistance of the latter. A suitable electrode holder is also descr ibed, and considerations for choosing the electrode materials, selecti ng the contact wires, preparing the sample, and creating a weld are di scussed. (C) 1998 American Institute of Physics. [S0034-6748(98)02307- 7].