<title>Thermal deformation measurement of electronic packaging component using AFM scanning moire method</title>

Abstract

ABSTRACTThe AFM scanning moire method was proposed to measure the in-plane deformation in the micrometer scale.The principle and technique for measuring in-plane deformation using AFM scanning moire method aredescribed. This method was applied to measure the thermal deformation in a quad flat pack (QFP) electronicpackage at 100°C. The normal strain component c, and the shear strain component y, near the die in the QFPpackage were measured. Keywords: AFM scanning moire method, electronic packaging, high frequency grating, thermal deformation 1. Introduction With the development of microelectronics and micro-machining engineering, more powerful and lower cost microelectronics products have been the driving forces in the technological advances of electronics packaging. Thetendency of the electronic packages is much smaller, more functional and powerful than ever before. Due to the coexistenceof variety materials with different coefficient of thermal expansion in the electronic packages, reliability becomes aninteresting problem, especially with smaller package sizes. The thermal mismatches often result in the delamination ofinterfaces between two materials, which eventually leads to ultimate mechanical and/or electrical failure. Additionally, withthe increasing application of the micro-electro-mechanical systems (MEMS), the failure of MEMS components becomes anew interesting point for us. In the above mentioned problems, the interface between two materials or components (in theelectronic package and MEMS) is in a size from few tens micron to 0.1mm. It is very difficult to utilize the conventionalmethods to measure the deformation in such a small area. Moire interferometry was employed in the analysis of thermaldeformation in electronic packages'. When moire interferometer is used to measure a deformation in a micro-area, anobjective lens for microscope is utilized to magnify the measured area. However, the magnifying power of the objectivelens is always fixed, and less than x40. Hence, it is difficult to observe the area with different magnification using thismethod.From 1990's, with the development of nanotechnology, the scanning probing microscopy techniques have been widely usedfor the processing, manufacture and measurement from micro- to nano-scale. In consideration of the character of highresolution of AFM, it can be utilized to measure in-plane deformation in a micro-area with high sensitivity. In this study,the AFM scanning moire method is applied to determine the thermal deformation of QFP electronic package. A holographicgrating with the frequency of 1200 lines/mm is adhered to the measured area in the packaging using epoxy resin. The