The development of a top-bottom-BGA (TB-BGA)

A “top bottom ball grid array” (TB-BGA) is described, that takes advantage of existing BGA- and CSP-techniques, to create a new package for SCMs, MCMs, sensors and actuators. By using a pin-compatible BGA configuration at the bottom and the top of the carrier, a 3D stack assembly of several TB-BGAs is possible. Considering thermomechanical reliability, the compact stack assembly reduces bending loads and shear forces by using suitable materials, The area configuration of solder balls ensures a good thermal conductivity. As demonstrators, ceramic TB-BGAs are actually developed as single chip modules (SCMs) and few chip modules (FCMs). They will be mounted as intelligent sensor bus interfaces in conventional sensor casings. A full operating 16-bit-processor-unit including microcontroller, S-RAM, EEPROM physical CAN bus interface, oscillator and SMD components will require a volume of only 1.5 cm³