Voltage in-situ electrical metrology for test-to-failure BGA component shock margin assessment

Abstract

As customers embrace new mobile market segments, electronic systems containing direct ball grid array (BGA) components will inevitably experience greater stresses resting from shock and drop events during their use. These events can result in BGA field failures especially when the product is exposed to solder joint or material excursions. Such issues could result in significant loss to the manufacturer in terms of line downtime or warranty returns. The current screening metrologies used for detection of BGA product solder joint failures are either time consuming, unreliable, or inefficient. Some of these methods can only be used with traditional daisy chain (DC) test packages and do not readily enable electrical monitoring of individual joints (or ball-level). To address the above problems, an innovative solution is required. This paper introduces a new cost-effective, efficient and reliable metrology also called voltage metrology to electrically detect ball-level failures in-situ on live product BGA components during the shock event. First, the metrology validation results collected on the product components are reviewed to demonstrate robustness. The benefits of this metrology are highlighted using drops-to-failure probability approach which is commonly used in the cell-phone industry. The data is used to compare the relative performance across different products, which is a common query from original design manufacturers (ODMs) and original equipment manufacturers (OEMs). This paper also presents examples showing how ball-level damage progression can help enable board design optimization through better printed circuit board (PCB) pad design and sacrificial pin definition. In addition, a case study is presented to demonstrate metrology effectiveness towards development of shock acceleration models. Finally, the paper shares necessary test vehicle (TV) design modifications to activate ball-level monitoring feature on traditional DC test coupons.