Fabrication Of Gold-Tin Solder And Packaging Study On High Power Semiconductor Lasers

Creep and electrical movement of solders usually occurred in high power semiconductor lasers and linear-array semiconductor lasers packaged with soft solders such as In or Pb-Sn.Soft solders are relatively weak in enduring fatigue in device operation and chip bending, deformation may be caused due to thermal strain in packaging process, which would seriously influence the beam quality and aging time of devices.Study on the thermal characteristics and packaging process of high power semiconductor lasers has been presented in this work. The bonding technology and heat dissipation characteristics of high power semiconductor lasers with different solder materials and solder structures have been researched theoretically and experimentally in detail focused on high power QW lasers. Main works are summarized as the following:1. The temperature distribution as well as the thermal resistances of high power QW lasers with epi-side down mounting forms have been obtained, the effect of mounting structures and process on laser thermal characteristics has been discussed.2.A new bonding structure by A1N ceramic plate used as matching submount between laser chip and copper heat sink and Au-Sn alloy as solder have been designed. An acid electroplating solution of Au was prepared and and the electroplating equipment was designed and set up based on our experiment condition. The optimal conditions for uniform and smooth thick Au electroplating with acid solution were studied, qualified Au depositing layer was obtained, which was satisfied for device bonding.3.By magnetron sputtering, electroplating and thermal evaporating process, multiple metal layers for device bonding were prepared and deposited onto A1N submount .The soldering process of Au-Sn alloys for device bonding was studied and the soldering condition was optimized.4. The packaged high power QW lasers were characterized by using I-V and P -I methods., the thermal resistances of the laser device decreased, which confirmed the design of the mounting process.