Understanding the effect of molding compound mechanical properties on the electrical performances drift of hall effect sensor

摘要

The innovative technology of hall effect sensor (HES) has proven to reach new level in electronic industry. However, it is undeniable that new technology also needs time to be developed into the perfect product. The hall sensor had experienced some issues related to the electrical performance. Several possible factors such as IC design, humidity, delamination, compound visco-elastic property, thermal aging and die attach glue have been included as the cause to this problem. Research studies collaboration between Carsem (M) Sdn. Bhd. and Customer Z was achieved in order to understand the relationship between the electrical performance of hall sensor and the mechanical properties of molding compound. Thermal hysteresis test by Customer Z resulted in sensitivity drift approximately more than 1.5%. The shifts in the hysteresis cycle indicate that the HES is experiencing internal stress from the package. Two types of mold compound were tested in Carsem Technology Centre (CTC) Material Lab at Carsem (M) Sdn Bhd under different post mold cure condition. These mold compound thermal and mechanical properties was determined using in-house lab equipment such as thermal mechanical analyzer (TMA) and dynamic mechanical analyzer (DMA). This technical paper will explore the new method used to predict mold compound stability using TMA equipment and its correlation with the thermal hysteresis of the electrical sensitivity drift. Other testing such as thermal aging, stress relaxation by DMA equipment and moisture absorption test will be further discussed as we conclude the most suitable mold compound to be used in the production of HES package.