关键词: 塑料封装, 分层失效, Die-EMC界面, 失效机理, 制程优化, 可靠性, 表面贴装

Abstract: Plastic packaging is the mainstream packaging form for semiconductor integrated circuits. Its non‑hermetic structure makes it prone to delamination failure. Aiming at the high-temperature no-output and Pin 2 open-circuit failure of TSSOP-8 surface-mount plastic encapsulated chips, this paper adopts X-ray inspection, C-SAM, cross-section analysis and EDX energy spectrum analysis to clarify the chain failure mechanism of such devices: delamination at the Die-EMC interface of such devices induces interfacial stress concentration, which further causes mechanical solder ball pull-out, and ultimately results in pin open circuit failure. This study quantifies delamination from a "potential reliability risk" to a "direct inducement of functional failure", establishes the correlation criterion between delamination area and electrical performance failure, and reveals that thermal expansion coefficient mismatch, insufficient interface activation, oxidation and moisture absorption are the dominant causes of delamination. On this basis, a three-in-one process optimization scheme is proposed, including plasma cleaning, nitrogen anti-oxidation storage, and precise control of residence time in key processes. Tests and mass application results show that after optimization, following 200 temperature cycles ranging from -55 ℃ to 155 ℃, the maximum delamination rate of devices is reduced from 100% to 0%. Solder ball detachment and functional failure are completely eliminated, and the overall device reliability is significantly improved. Independent of material replacement and structural modification, the research findings provide theoretical basis and engineering reference for delamination prevention and control as well as process iteration of high-reliability surface-mount plastic encapsulated devices.

Key words: plastic packaging, delamination failure, Die-EMC interface, failure mechanism, process optimization, reliability, surface mount