温循与振动条件下三种加固方式的BGA焊点可靠性评估

Reliability Evaluation of BGA Solder Joints with Three Reinforcement Methods Under Temperature Cycles and Vibration Conditions

围绕球栅阵列(BGA)封装器件加固,建立器件和板级有限元模型,分析在温循和随机振动条件下螺钉紧固、底部填充及局部点胶三种加固方式对BGA焊点可靠性的耦合作用规律。结果表明:静应力下,相比局部胶加固方式,底部填充方式会将螺钉紧固引起的变形传递给所有焊点,从而使焊点整体静应力处于较高水平;温循应力作用下,螺钉安装距离相同时,加固方式相较于螺钉位置对焊点热应力的影响更大,四角L形点胶加固方式具有更低的焊点热应力;振动应力作用下,螺钉紧固方式与局部点胶加固方式对降低随机振动应力均有积极作用,当螺钉位置与点胶加固位置交叉分布时,抗振性能最优。研究结果可为BGA印制件的结构设计与加固工艺设计提供参考。

The coupling effect rules of three reinforcement methods such as screw fastening,under-filling and local dispensing on the reliability of ball grid array(BGA)solder joints under temperature cycles and random vibration conditions were analyzed by establishing the finite element model of device and printed board assembly around the BGA package device reinforcement.The results show that under the stasic stress,compared with local dispensing reinforcement method,the underfill method will transfer the deflection caused by screw fastening to all solder joints,making the overall static stress of solder joints at a high level.Under the temperature cyclic stress,the influence of reinforcement method on the thermal stress of solder joints is greater than that of screw position for the same mounting distance,and the four-corner L-shape dispensing reinforcement method has lower thermal stress of solder joints.Under the vibration stress,both screw fastening and local dispensing reinforcement methods have positive effect on reducing random vibration stress.When the screw position and dispensing reinforcement position are cross-distributed,the vibration resistance is the best.The research results can provide reference for the structural design and reinforcement process design of BGA printed board assembly.