长期贮存下电路镀层结构可靠性与失效分析研究

Research on reliability and failure analysis of circuit coating structure after long⁃term storage

针栅阵列(PGA)封装用于高速大规模逻辑LSI电路,其引脚、焊盘等关键接触位置的结构至关重要,一般情况下在表面镀涂不活泼金属(如金),保护基材不受腐蚀。若该位置的镀层结构在环境因素的影响下产生腐蚀,可能对器件的可焊性产生影响,造成参数漂移、性能退化等问题,甚至发生短路或断路失效,从而降低集成电路的寿命与应用可靠性。因此,通过扫描电子显微镜(SEM)和能谱分析仪(EDS)等对镀层表面形貌、焊盘腐蚀生成物及其成分进行分析,研究经长期贮存后电路镀层结构的腐蚀行为和机理。结果表明,镀层结构表面存在微小孔隙,在水汽、灰尘或其他杂质离子的长期作用下,下层活泼金属反应生成污染离子,其通过孔隙迁移到表面聚集形成腐蚀物,从而造成外观失效,影响电路的性能与应用。

Pin grid array(PGA)package is used in high⁃speed and large⁃scale logic LSI circuit,and the structure of key contact positions such as pins and pads is crucial.The inactive metal(such as Au)is coated on the substrate to protect the substrate from corrosion under normal circumstances.If the coating structure at this location undergoes corrosion under the influence of environmental factors,it may affect the solderability of the device,causing problems such as parameter drift,performance degradation,and even short circuit or open circuit failure,reducing the lifespan and application reliability of integrated circuits.Scanning electron microscope(SEM)and energy dispersive spectrometer(EDS)are used to analyze the morphology,corrosion products and their composition on the surface of the coats.The corrosion behavior and mechanism of circuit coating structure after long⁃term storage are researched.The results indicate that there are small pores on the surface of the coating structure.Under the long⁃term action of water vapor,dust,or other impurity ions,the active metal in the lower layer reacts to generate pollution ions,which migrate to the surface through the pores to form corrosive substances,resulting in appearance failure and affecting the performance and application of the circuit.