Computational material property simulation for laminated composites

Mechanical property of laminated composite plate, such as substrate and printed circuit board are critical in package mechanical modeling, especially for package overall response and die stresses. These laminates are often orthotropic materials, which has a set of 9 independent parameters. Layers in the laminates may consist of different materials. Material composition and distribution patterns affect the layer properties, which in tern affect the properties of the laminates. There are literatures regarding computing of some material parameters of laminates, but fall short to provide all independent parameters. Lack of entire set of material parameters for a laminate makes it difficult to provide input data for mechanical simulation. A computational material property simulation method is presented in this work. As the first step, the mechanical and CTE properties of each laminate layer are simulated. An FEM mesh is first generated based on bit map form of circuit physical layout. Each layer is simulated with one thermal loading and 6 mechanical loadings: three simple tensions and three shears. From simulation results, 12 orthotropic material properties and three CTE values are obtained, among which three Poisson´s ratios are dependent. The dependency relations are used to verify the simulation validity. With material properties of each layer, the laminate model can be modeled and simulated in the way similar to the layer simulation. The simulation processes are automated with ANSYS APDL language. The results are compared with available theoretical cases and show excellent agreement