Failure Analysis Techniques Applied in Resolving Hybrid Microcircuit Reliability Problems

The failures discussed in this paper are those that are not presently easy to detect with conventional screening. This summary contains a series of recommendations for additional surveillance to assure more reliable hybrids. 1- Add a high temperature bake to qualify a bonding process. At least quarterly on Class B hybrids and on a lot to lot basis for Class A devices. Should failure occur the frequency of testing should be increased. 2- If multilevel substrates are used some hybrids should be sectioned to check for quality level. If possible vias should not connect more than two adjacent levels and chips that generate heat should be kept on the first level. 3- PIND testing should be instituted at the hybrid manufacturers as an on line process check and improvement technique. Users should also use PIND testing as a check on what process,if any,is generating oose particles. 4- Check chip capacitors at Incoming Inspection to see if any contaminants are trapped in the end terminations. 5- The present pre-cap visual should be modified to allow for rejecting parts with spittle droplets in them. 6- Institute a regular check on hybrids to determine the level of moisture resulting from the manufacturer's process. This test should be carried out using one of the methods described in the pending test method 5008 of Mil-Std-883. The levels should be below 1000 ppm (parts per million) rather than the 6000 ppm minimum called for in test method 5008.