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Gold-tin solders in 80%-20% ratio are used to mount commercial 1 watt laser diodes soldered on chemical vapor deposition diamond heat sinks. An additional metallization of 2 micrometers gold reduces the mechanical stress in the laser diode and forms reproducible bonds. An analytical model calculates the maximal shear, tensile, and peel stress. High resolution X-ray microscopic results show the absence of voids in the bond interface. The results of the burn-in and the first-accelerated aging tests are presented.

Fluxless flip-chip bonding on various thick film metallizations of green tape ceramic substrates utilizes gold/tin solder bumps combined with palladium-silver substrate. Reliability data show that the use of underfill improves contact performance. The contact resistance shows no measurable decrease after 6500 thermal cycles and after exposure of more than 1000 hours. The results of temperature ageing tests, humidity exposure tests, and pressure cooker tests confirm the reliability of fluxless flip chip interconnections.

Tape automated bonding devices having a 75 micrometer pitch show the highest reliability when the thickness of the Au-tape metallization in the outer lead bonding solder fillet is 0.8 micrometers. The high Au-concentrations improve solder wetting behavior and show better solder fillet formation and mechanical behavior. Low Au-concentrations give lower mechanical pull test values after bonding, thermal ageing, and cycling. The effects of intermetallic Au-Sn phases, Kirkendall pore formation, ternary Cu-Sn-Au compound formation, and amount of Sn in the fillet are analyzed.

A study of the thickness changes between the gold and solder in a Tape Automated Bonding (TAB) outer lead bond reveals the Au-concentration in the outer lead bond (OLB) contacts. A critical concentration of gold is present in the TAB packages, which reduces the reliability of the TAB-bonded devices. The critical Au concentration is 9 wt%.

Investigation of the tin and gold plated tapes on FR4 substrates having tin-head solder by a bond parameter study reveals that a high thermomode temperature is required for the functioning of Au-plated tapes. The study also reveals that it is possible to laser solder the tin and gold tape metallizations on tin-lead solder pads for high temperature applications.

The investigation of Au-Sn-Cu and Au-Cu metallurgies in the inner lead bond area reveals the influence of diffusion in the ternary Cu-Sn-Au system on the dependability of ILB contacts. A strong degradation of the forces by Kirkendall pore formation is caused by an aggregation of the eutetic Au/Su alloy, which is in direct contract with copper. The mechanism of pore formation, pore growth and coagulation causes the adhesion in the ILB contacts. Proper formation of bond parameters eradicates the Kirkendall porosity.