湿热环境下微电子互连ACF的导电及腐蚀行为

Electronic conductive attributes and corrosive behavior of ACF under thermal humid conditions for microelectronic interconnection

各向异性导电胶膜(anisotropic conductive adhesive film,ACF)替代锡铅(Sn/Pb)钎料已应用于微电子封装中。以聚苯乙烯微球(Polystyrene,PSt)(3～5μm)为导电核心体,其表面化学镀一层Ni粒子(1～2μm)形成的复合微球填充在树脂中形成的各向异性导电胶膜作为研究对象,采用交流阻抗和动电位扫描等方法,探讨了湿热环境下ACF胶膜导电及耐蚀性能。实验表明,高温(80℃)和高湿(RH85%)中老化4h后,各向异性导电胶膜的接触电阻有较显著的增加,所致原因是湿热环境下起导电作用的Ni粒子氧化阻止了电流穿越,且温度的影响大于湿度的影响,两者协同作用加速各向异性导电胶膜(ACF)互连失效。对比实验表明,ACF耐腐蚀性能明显高于锡铅钎料,原因是基体胶对导电粒子的保护作用,阻碍了腐蚀介质向内部扩散。

Anisotropic conductive adhesive film（ACF） is chosen to substitute for Sn/Pb solder and applied to microelectronic packaging.In this thesis,ACF is composed of polystyrene microspheres（PSt）（3~5 μm） plated with a thin Ni particles（1~2 μm） outside and a special epoxy resin.Both of them are mixed to be ACF.Electronic conductive attributes and corrosive resistance behavior of ACF are analyzed by alternating current impedance measurement and potentiodynamic polarization under highly thermal humid conditions.The results show that after aging 4 h in 80 ℃ and 85% RH condition,contact resistance of ACF increases greatly,and the main reason is the oxidation formation of Ni prevents electric current from going through.Furthermore,the effect of temperature on corrosive behavior of ACF exceeds the effect of humidity,and both of them accelerate the failure of ACF reliability in microelectronic interconnection.Corrosion resistances of ACF are better than that of Sn-37Pb solder in the same case.The possible reason is that Ni is protected by the base epoxy resin,and dispersion of corrosive medium into adhesive interlayer is held back.