| abstract |
A test assembly for testing a high density circuit or a test board, which comprises a test head containing a mirror image circuit of the circuit to be tested on the test board, a plurality of test points on the test head circuit, the test points comprising a plurality of metal pads, and metal contacts soldered to the metal pads, the metal contacts being in the form of metal balls or flakes selected from the group consisting of brass, bronze or copper, of a size ranging from about 5 to about 30 mils. The test head is positiioned over the test board with the metal contacts on the test head in contact with corresponding test points on the high density circuit on the test board. Means are provided for connecting the circuit on the test head with a tester, thereby providing signals from the high density circuit under test through the test head circuit to the tester. A solder composition is provided which is especially adapted for soldering the metal contacts to the metal pads on the test head. Such solder composition comprises a liquid vehicle, finely divided solder metal dispersed in the vehicle, the solder metal having a particle size ranging from 40 to 70 microns, and additional metal particles dispersed in the vehicle, the additional particles being in the form of metal balls or flakes selected from the group consisting of brass, bronze and copper, the additional metal particles having a size ranging from about 5 to about 30 mils and being present in an amount ranging from about 5 to about 60% by weight of the total composition. |