STRESS-ANALYSIS OF PRINTED-CIRCUIT BOARDS WITH HIGHLY POPULATED SOLDER JOINTS AND COMPONENTS - A MICROMECHANICS APPROACH

The single most difficult aspect for thermo-mechanical analysis at the board level lies in to an accurate accounting for interactions among boards and small features such as solder joints and secondary componen ts. It is the large number of small features populated in a close neig hborhood that proliferates the computational intensity. This paper pre sents an approach to stress analysis for boards with highly populated small features (solder joints, for example). To this end, a generalize d self-consistent method, utilizing an energy balance framework and a three-phase composite model, is developed to obtain the effective prop erties at board level. The stress distribution inside joints and compo nents are obtained through a back substitution. The solutions presente d are mostly in the closed-form and require a minimum computational ef fort. The results obtained by present approach are compared with those by finite element analysis. The numerical calculations show that the proposed micromechanics approach can provide reasonably accurate solut ions for highly populated printed circuit boards.