Prediction of High-Speed Oscillator Frequency Drift Under Package Level Reliability Tests

The touch controller is prevalently adopted in mobile devices and laptops as a touch screen and touchpad, respectively. Synaptics is the major player and is working on enhancing user interaction and developing minimal controller sizes and low-power designs. In addition, Synaptics' designs pursue fast response rates, noise immunity, high sensitivity with glove wearing, etc. To satisfy such challenging characteristics and ensure it is working properly during operation, the evaluation of reliability tests becomes crucial. Temperature and humidity are common environmental factors that can lead to material aging and influence the physical properties of electronic devices. High-temperature storage tests (HTST), thermal cycling tests (TCT), and highly accelerated stress tests (HAST) are utilized to accelerate life evaluation and simulate user operation conditions, as defined by JEDEC. Under long-term storage at high temperatures and humidity conditions, the frequency drift of the high-speed oscillator (HSO) exceeded 1%. Therefore, this paper studied different package combinations for wire bonding ball grid array (WBBGA) designs, including polyimide coating, thicker die, and material properties of the die-attach film (DAF). After reliability and functional tests, the frequency drift percentage would vary with changing stress levels according to the corresponding designs. Finite element analysis software was used to clarify the effect of each factor.