基于DIC的多层板热翘曲实验及仿真研究
EXPERIMENTAL AND SIMULATION RESEARCH ON THERMAL WARPING OF MULTI-LAYER PLATES BASED ON DIC
-
摘要: 在微电子封装中, 普遍存在由不同材料组成的多层板结构, 当温度变化时, 各层级材料的热膨胀失配将会导致热翘曲现象, 而过大的翘曲将导致芯片开裂、芯片分层、焊点失效等封装失效问题, 因此针对典型多层板结构的热翘曲问题的研究非常有必要. 文章基于三维数字图像相关方法(DIC) 搭建热翘曲测量平台, 对多层板升温过程中的热翘曲进行实验测量. 利用红外热像仪温度成像结果修正仿真过程中的温度加载曲线, 建立了多层板热翘曲的等效仿真模型, 并对热翘曲仿真结果和实验结果进行对比验证. 在实验和仿真分析中, 讨论了板厚度、材料属性和层数对热翘曲值的影响. 进一步利用基于DIC的热翘曲测量技术对芯片表面翘曲值进行测定, 并与白光干涉法测量结果进行了对比验证. 研究结果表明, 在升温过程中, 基于DIC技术测量得到的多层板热翘曲结果与仿真结果吻合较好, 单层材料和厚度的变化对翘曲影响较大. 使用DIC和白光干涉法测量得出的芯片表面翘曲结果一致, 基于DIC的测量技术可为微电子封装中典型多层结构的热翘曲测量提供有效途径.Abstract: Multilayer structures composed of different materials are widely used in microelectronic packaging. When temperature changes, thermal expansion mismatch of materials at different layers will lead to thermal warping, and excessive warping will lead to chip cracking, chip layering, solder joint failure and other packaging failure problems. Therefore, it is necessary to study the thermal warping of typical multilayer structure. In this paper, the thermal warpage measurement platform was built based on the three-dimensional digital image correlation method (DIC) to realize the real-time observation of thermal warping process of multilayer plate. In the heating process, the thermal warping of typical double-layer and triple-layer plates with different thicknesses and materials were measured respectively. Furthermore, the finite element simulation of thermal warping of multilayer plates was conducted according to experimental conditions, in which the temperature loading curve was obtained by modifying the measured temperature results by infrared thermal imager. The thermal warping simulation results and experimental results were compared. According to experimental and simulation results, the effects of plate thickness, material properties and number of layers on the thermal warpage value were discussed. Moreover, the warpage measurement technology based on DIC was used to measure the warpage value of a chip at room temperature, and the results were compared with that by using the white light interference method. The results show that the thermal warpage results of multilayer plates measured by DIC method are in good agreement with the simulation results in the heating process. And the variation of single layer material and thickness has great influence on warping. For the QFN128 package, the surface warpage results measured by DIC method and white light interference method at room temperature are consistent. The DIC method can provide an effective way to measure the thermal warpage of typical multilayer structures in microelectronic packaging.