RELIABILITY OF DOPED BALL GRID ARRAY COMPONENTS IN THERMAL CYCLING AFTER LONG-TERM ISOTHERMAL AGING

摘要

Dopant levels of the solder paste alloys strongly affect the performance of the solder joints on laminate assemblies exposed to high-stress environments. For this study, reliability of solder pastes with various dopant levels were examined through thermal cycling. The reliability of the solder paste in multiple applications is important throughout many industries. Two substrate material were used in testing: FR4-06 and Megtron6. Each Printed Circuit Board (PCB) assembly consisted of CABGA, CTBGA, CVBGA, PBGA, SBGA, and SMR components. This paper will focus on Super Ball Grid Array components (SBGA304 and SBGA600). Three separate solder paste materials were used with matched solder joints. The PCB assemblies were isothermally aged for 0, 12, and 24 months at 75C to study the effect of log-term aging on the reliability under harsh thermal cycling. The test vehicles were subjected to thermal cycles of-40°C to 125°C on a 120-minute thermal profile, with a 15-minute dwell time at each extreme, and a 45-minute ramp time at a rate of 15°C per minute, in a modified JEDEC JESD22-A104-B single-zone environmental chamber. Each test vehicle was subjected up to 3000 thermal cycles. Failure analysis was performed to measure the reliability of the solder joints throughout all applications using Weibull charts and other data graphing tools. Failure percentage was measured by the amount cycles or amount of time the solder paste could withstand without causing a failure at the joint. Result shows a systemic adverse effect of again time on SBGA components reliability in thermal cycling. It also indicates that even components that show similar initial reliability trends may display differences following aging.