Abstract
Radar is currently employed in automotive applications to provide the range, angle, and velocity of objects using RF waves (77GHz). This paper outlines solder joint reliability of a specific micro-processor that processes data received from a SRR (short range radar operating from 0.2 to 30 meters). It is a powerful digital signal processing accelerator, which targets safety applications that require a high Automotive Safety Integrity Level (ASIL-B). The paper explores the package design and construction, SMT (surface mount technology) assembly, and board level reliability testing of various BGA pad surface finish and solder ball alloy materials on a 0.65 mm pitch, 10 × 10 mm body 141 MAPBGA (mold array process-ball grid array) package. The package configurations include two BGA pad surface finishes (Ni/Au and OSP [organic solderability protectant]) and three solder alloys (SnAg, SAC405, and SAC-Bi [a Bi containing SAC derivative]). Solder joint reliability analysis was performed through AATS (air-to-air thermal shock) between 40°C and +125°C and JEDEC Drop Testing at 1500G's. Thermal shock was extended until at least 75% of the populations failed, which was well past the points needed to qualify the packages for the intended end-use applications. The evaluations of the micro-processor indicate that the MAPBGA package can meet the ASIL-B specification requirements with optimized combinations of BGA pad surface finish and solder alloy. The focus of this paper was to determine the baseline solder-joint thermal shock and JEDEC drop performance with varied BGA pad surface finish and solder ball alloy materials.
