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THE IMPACT OF GLASS STYLE AND ORIENTATION ON THE RELIABILITY OF SMT COMPONENTS


 Printed circuit board (PCB) glass style and orientation can have a significant influence on thermal cycling reliability of surface mounted components. DfR has conducted thermal cycling (−40°C to 125°C) tests on two PCB glass styles (1080 and 7628). The in plane and out of plane Coefficients of Thermal Expansion (CTE) were measured and found to be about 3–4ppm/°C different in the X-Y directions of the boards. To facilitate the reliability assessment of SMT component reliability four 0-ohm resistor sizes (2512, 1206, 0602 and 0402) were mounted on each board. Each board had 20 resistors with multiple orientations. The overall sample size consisted of 32 resistors of each size per glass style. In addition, the PCBs have two pad sizes. The purpose of these experiments was to develop a model for validating fatigue life predictions for different laminate materials. This paper will present the experimental structure, results of the stress tests and variables on the reliability of the chip components and insight into the development of appropriate models.