基于埋置式基板的3D-MCM封装结构的研制

研制一种用于无线传感网的多芯片组件（3D-MCM) . 采用层压、开槽等工艺获得埋置式高密度多层有机（FR-4）基板，通过板上芯片（COB) 、板上倒装芯片（FCOB) 、球栅阵列（BGA）等技术，并通过引线键合、倒装焊等多种互连方式将不同类型的半导体芯片三维封装于一种由叠层模块所形成的立体封装结构中；通过封装表层的植球工艺形成与表面组装技术（SMT）兼容的BGA器件输出端子；利用不同熔点焊球实现了工艺兼容的封装体内各级BGA的垂直互连，形成了融合多种互连方式3D-MCM封装结构. 埋置式基板的应用解决了BGA与引线键合芯片同面组装情况下芯片封装面高出焊球高度的关键问题. 对封装结构的散热特性进行了数值模拟和测试，结果表明组件具有高的热机械可靠性. 电学测试结果表明组件实现了电功能，从而满足了无线传感网小型化、高可靠性和低成本的设计要求.

Development of a Three-Dimensional Multichip Module Based on Embedded Substrate

A new type of 3D multichip module (3D-MCM) for wireless sensor networks is developed based on embedded FR-4 substrate,in which FCOB (flip-chip on board),COB (chip on board),BGA (ball grid array) technologies,and wire bonding and flip-chip interconnection technologies are combined.The PBGA device and bare die are hybrid-integrated on the embedded multi-layer FR-4 substrate.By solder ball placement and reflow,the BGA is formed at the bottom of the 3D-MCM.Solder balls with different melting points are used for initial and final vertical interconnections for the sake of compatability of all levels of interconnections of the BGA by reflow soldering.The application of embedded substrate solves the problem that the top surface of the wirebonded chip overtops the solder balls under the condition that the chip was assembled on the same side of the substrate as the BGA of the MCM.The thermal management is conducted and the thermal related reliability of the 3D-MCM is simulated and evaluated.This kind of packaging structure satisfies the electrical performance and thermal requirement,and meets the challenge of minimization,high reliability,and low cost of the package design for wireless network.