Component Placement on Antisotropic Substrates
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15
Proper orientation of components on substrates with anisotropic coefficients of thermal expansion can enhance product life by minimizing strains produced in solder joints by temperature cycling. This placement minimizes thermal strains, and the following analysis thereof leads to an optimum shape for components on anisotropic substrates that maximizes component area while minimizing thermal strains. (Image Omitted) Solder joint reliability is maximized when components are placed in a way which minimizes the cyclic strain induced by thermal cycling. This is usually accomplished by matching the thermal coefficent of expansion (TCE) for the component and substrate as closely as possible. Some circuit board materials, such as some epoxy-glass laminates, have TCEs which are anisotropic in the plane of the card.