PCB树脂基体复合材料在焊盘坑裂失效中的断裂机理及板级机械可靠性研究

项目名称： PCB树脂基体复合材料在焊盘坑裂失效中的断裂机理及板级机械可靠性研究

项目编号： No.61474095

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 无线电电子学、电信技术

项目作者： 李世玮

作者单位： 香港科技大学深圳研究院

项目金额： 70万元

中文摘要： 近十年来，焊点受到机械载荷，导致焊盘底部的印刷电路板（PCB）树脂基体发生断裂，造成焊点与PCB分离的失效模式，即所谓的焊盘坑裂（Pad Cratering），在电子器件的生产，组装以及各种机械测试中越来越频繁的出现，成为无铅制成下焊点的主要失效模式之一。然而，对该失效模式的产生机理目前尚无深入的研究。本项目结合对PCB树脂基体的材料分析，焊盘抗坑裂强度的机械测试，以及断裂形貌分析，来研究不同PCB树脂基体体系的焊盘坑裂形成机理，并且对不同程度的热冲击下焊盘坑裂模式与强度的变化进行比较。同时，结合有限元仿真，研究在板级机械测试中，焊盘底部的应力/应变分布，分析组装后的印刷电路板组件（PCBA）的整体应变与焊盘局部应变的关系，以建立焊盘坑裂在板级测试中的应变失效准则。

中文关键词： 可靠性设计；电子封装；失效机制

英文摘要： Over the last decade, the electronics manufacturing industry has gradually but firmly entered the Lead-free era. However, the fracture inside the epoxy matrix underneath a copper pad causing a separation of the copper pad and a solder joint failure, known as pad cratering, happens more and more frequently during the manufacturing process or mechanical reliability tests. It has become one of the dominant failure modes of the solder joint, and therefore draws an increasing attention all over the world. However, the fracture behavior mechanism of pad cratering is still not well understood, thus it becomes the motivation for us to propose this project. In this project, PCB samples will categorized by different curing agent (Dicy and Phenolic) of the resin matrix, and their material properties, including thermal properties and Vickers hardness, will be analyzed and compared. The pad crater strength and the fracture morphology will be inspected to investigate the fracture mechanism of pad crater, and the thermal impact effect will also be evaluated. Then, the PCB assembly board level mechanical tests will be conducted. And the performance of different PCBs with regard to pad crater failure will be evaluated. The stress/strain distribution at the pad area will be analyzed with the aid of finite element simulation. A strain-criterion for pad crater failure will be established by relating the global strain with the copper pad local strain.

英文关键词： Reliability;Electronic Packaging;Failure Mechanism