Verification of Numerical Models Used in Microelectronics Packaging Design by Interferometric Displacement Measurement Methods

Abstract

Verified/predictive modeling has become an integral part of electronic packaging product development in order to reduce costs and cycle time. In this paper, interferometric displacement measurement methods are utilized to verify the validity of numerical models for microelectronics packaging design. Three optical methods with submicron sensitivities are employed: moire´ interferometry, microscopic moire´ interferometry and Twyman/Green interferometry. The first two provide contour maps of in-plane displacement fields, and the third maps out-of-plane displacement fields. Their high sensitivity and high spatial resolution make them ideally suited for verification of numerical models. By combining numerical modeling and experimental verification until the results merge, numerical models become more accurate and dependable. Then, the models can be applied extensively to optimize the package designs with confidence that the models provide effective information on material and geometry sensitivity.

Recent Applications of Moiré Interferometry

“…Thus, the deformation incurred by the temperature increment is locked into the grating and recorded at room temperature. Numerous examples can be found in the literature [20,21,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”

Investigation of long-term reliability and failure mechanism of solder interconnections with multifunctional micro-moiré interferometry system

“…Different experimental photo-mechanics techniques, including geometry moir e (GM) [16], moir e interferometry (MI) [17], holographic interferometry (HI) [18], speckle interferometry (SI) [19], electronic speckle pattern interferometry (ESPI) [20], and digital image speckle correlation (DISC) [21], have been developed to evaluate the deformation of microelectronic packages in the stages of design, fabrication and product. On the other hand, many people use the two major experimental reliability qualification techniques, i.e., temperature cycling (TC) and thermal shock (TS), to assess the long-term reliability of microelectronic packages.…”

Mapping of mechanical, thermomechanical and wire-bond strain fields in packaged Si integrated circuits using synchrotron white beam X-ray topography

“…In the case of scanning acoustic microscopy the resolution is dependent on frequency (typically 10-100MHz) and hence on depth [16], [17]. Moiré interferometry [18]- [20] and indeed microscopic Moiré interferometry [22] has been used successfully to provide contour maps of in-plane displacement fields with high sensitivity and high spatial resolution. For example, the Moiré fringes observed in [18] corresponded to deformations of the order of 0.4 m, which, for the package structures studied, correspond to observed strains of the order of 10 .…”

“…Current approaches include a) finite element modeling (FEM) [9]; b) the positioning of miniature strain gauges especially using piezoresistive stress sensors [10]- [15]; c) scanning acoustic microscopy, in either C-mode or (scanning laser acoustic microscopy) SLAM-mode [16], [17]; d) using Moiré interferometry [18]- [22]; e) photoelastic techniques [23]- [26]. Each of these techniques possesses considerable merits and demerits, though naturally they are all useful for soliciting vital information about the state of strain in IC packages.…”