Failure Modes of InGaAsP/InP Lasers Due to Adhesives

Sudden failure modes for lnGaAsP/InP lasers were observed during aging. Growth of Sn whiskers, formation of voids between the heat sink and package stem, separation of metallized metal from the diamond heat sink, and reaction of solder material with laser chip were observed. Since they were found to induce sudden failures, the choice of bonding solders and metals for heat sink metallization is very important to obtain highly reliable lasers. A Au-rich Au-Sn alloy was found to be the most stable solder against the sudden failures among Sn, Sn-rich Au-Sn, Pb-Sn, and Au-rich Au-Sn.