High reliability LTCC BGA for telecom applications

The trend in the telecommunications industry is towards the usage of smaller packaging options while improving electrical and reliability performance. National Semiconductor, a producer of low temperature cofired ceramics (LTCC) and wireless components, strives to integrate these products into small, high performance modules. In particular, the module under development requires an LTCC substrate with ball grid array (BGA) ball attachment technique. This paper describes a series of experiments focused on materials selection required to produce high performance solder joints. Further evaluations were also performed to determine the printed circuit board (PCB) level reliability during thermal cycle life evaluation. This study evaluated commercially available LTCC pad metallizations and solder alloys, while also comparing several pad construction methods as a function of thermal cycle life. The results identify the key factors for material selection, which produced the maximum thermal cycle life for the LTCC BGA module.