Micromechanics of multilayer printed circuit boards

Lee, L. C.; Darekar, V. S.; Lim, C. K.

doi:10.1147/rd.286.0711

Cited by 16 publications

(1 citation statement)

References 7 publications

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“…(3) The bonding between all materials is able to withstand the subjected shear load. (7) The in-plane CTE mismatch which produces tension and compression in the copper is assumed to be less significant than the out-of-plane CTE mismatch. (4) The temperature is uniformly distributed throughout the PWB.…”

Section: Approach and Assumptionsmentioning

confidence: 99%

<title>Sensitivity study of printed wiring board plated-through-holes copper barrel voids</title>

et al. 1991

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Improved printed wiring board (PWB) manufacturing technology has resulted in more advanced methods for component mounting (such as surface mount technology). Evidence has shown that the new generation of PWBs cannot be built using surface mount technology (SMT) alone. Some passive components and connectors can only be mounted by using plated through holes (PTHs) and vias. Up to now, PTHs and vias are still the most widely used inter-layer connections in a PWB. The advanced miniaturization technologies has dramatically reduced the size of a PTH to as small as 5mils and the use of multilayer composite construction further increases the level of design complexity. It has been determined that PTH failure results from thermo-mechanical deformation due to mismatch of coefficients of thermal expansion (CTE) in the out-of-plane (Z) direction between board substrate and the PTH copper plating at elevated temperatures. Although many studies have been conducted concerning the general PTH design, what has not yet been evaluated in a systematic and comprehensive manner is the PWB failure resulting from copper barrel plating voids. A collaborative research effort between Georgia Tech and Motorola has recently been carried out to investigate the influence of voids on PTH failures. This study first identifies the basic key design parameters (such as void size, void shape, void location, copper plating thickness, etc.) relevant to void characterization. These parameters with selected values were collectively formed a parametric matrix and were evaluated using a finite element computer program to examine the strain level inside the copper plating. It is not the intention of this study to predict the actual failure mechanisms for the PTH design. The objective is to understand the impact of the existence of the copper barrel voids on the Pm design and to improve the inspection guidelines for PTHs.

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Section: Approach and Assumptionsmentioning

confidence: 99%