Electrically conductive adhesives for surface mount solder replacement
Electrically conductive adhesives for surface mount solder replacement
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用于表面贴装焊料替代的导电粘合剂
DOI：
10.1109/3476.558550
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
D. Napp
中科院分区：
文献类型：
--
作者：
M. Zwolinski;J. Hickman;H. Rubin;Yulia Zaks;S. Mccarthy;T. Hanlon;P. Arrowsmith;A. Chaudhuri;R. Hermansen;S. Lan;D. Napp
导电粘合剂为印刷电路板（PCB）表面贴装组件的附着提供了无铅、相对低温的工艺。国家制造科学中心（NCMS）导电胶粘剂项目定义了对各向同性导电胶粘剂（ICA）的要求。在这项研究中，25种市售的银填充环氧树脂在85/spl度/C/85% RH老化500小时后，在铜和锡/铅表面表面表面的结合电阻稳定性进行了评估。通过搭接剪切和冲击试验评估了材料的力学性能。该测试对表面贴装粘合剂提出了一系列要求，包括体积电阻率为1 m/spl Omega/-cm，老化后电阻变化小于20%，并且能够通过塑料铅芯片载体（PLCC） 44封装从1.52米（60英寸）的高度跌落6次。在筛选研究中确定的有前途的候选粘合剂在具有各种组件的电路板测试车上进行了评估。与焊接相比，组装显示了一个狭窄的加工窗口。冲击试验表明，目前的材料对许多部件的冲击强度不足，加速的T/H老化导致Sn/Pb成品部件的电阻不稳定。初步数据包括已开发的一种新的粘合剂配方，以解决目前可用的ica的缺点。
Electrically conductive adhesives offer a lead free, relatively low temperature process for attachment of surface mount components to printed circuit boards (PCB's). The National Center for Manufacturing Sciences (NCMS) Conductive Adhesives project has defined a requirement for an isotropically conductive adhesive (ICA). In this study, 25 commercially available silver-filled epoxies were evaluated for joint resistance stability on copper and tin/lead surface finishes after 500 h of 85/spl deg/C/85% RH aging. Mechanical properties were evaluated through lap shear and impact testing. This testing led to a set of requirements for a surface mount adhesive including a volume resistivity of 1 m/spl Omega/-cm, less than a 20% shift in resistance after aging, and the ability to pass six drops with a plastic leaded chip carrier (PLCC) 44 package from a height of 1.52 m (60 in). Promising candidate adhesives identified in the screening study were evaluated on a circuit board test vehicle with a variety of components. Assembly revealed a narrow processing window when compared to solder. Impact testing demonstrated that current materials have inadequate impact strength for many components and accelerated T/H aging reveals unstable electrical resistance with Sn/Pb finished components. Preliminary data is included on a new adhesive formulation that has been developed to address the shortcomings of currently available ICAs.