Semi-conductor devices are mostly encapsulated by epoxy molding compound (EMC) materials. During encapsulation, stresses are generated due to the curing of the molding compound. Moreover, additional stresses will build up during cooling down from molding to ambient temperature caused by the differences in the coefficient of thermal expansion. These residual stresses add up to the stresses generated during mechanical loading and may lead to product failure. The viscoelastic properties of the encapsulation material depend highly on temperature and degree of cure. In this paper, the thermo-mechanical properties of an epoxy molding compound with and without filler are investigated both experimentally and theoretically. The cure-dependent properties of the EMCs, likewise, the cure kinetics, coefficient of thermal expansion and cure shrinkage were measured using a Differential Scanning Calorimetry (DSC) and GNOMIX high pressure dilatometer. In addition using a Dynamic Mechanical Analyzer (DMA) the time and temperature dependent storage modulus was measured and mastercurves were constructed.@en

Interfacial delamination has become one of the key reliability issues in the microelectronic industry and therefore is getting more and more attention. The analysis of delamination of a laminate structure with a crack along the interface is central to the characterization of the interfacial toughness. Interfacial toughness is highly dependent of temperature, moisture and mode mixity. the present study deals with delamination toughness measurements of an epoxy molding compound - copper lead frame interface as directly obtained from a real production process in harsh environment, temperature >100 degrees C & 100%RH. To deal with it, a chamber with high pressure, i.e. pressure vessel or pressure cooker, is needed. Controlling the inside pressure makes it possible to have 100% RH at different temperature levels. In addition to the initial stress state due to the harsh environment, mechanical loading under combined mode I/II conditions is applied on a bi-material specimen to initiate and propagate the delamination. For this a mixed mode bending setup is installed in the pressure chamber.@en

Delamination between copper and epoxy molding compound (EMC) is one of the common failure modes in packages due to relatively weak adhesion at the interface. Delamination is difficult to predict because a package is often with a complex structure design constructed with different materials and under combined normal and shear loading. Development of cohesive zone elements applied in FEM has emerged into the application of cohesive zones as an effective tool for crack propagation simulation. In this study, a methodology to obtain useful parameters for cohesive zone modeling from experimental measurements is proposed. The approach is demonstrated with the adhesive joint between epoxy molding compound and copper that was under residual stresses and applied mixed-mode loading. The proposed approach to determine the traction-separation function does not rely on the uncertainties of crack tip stresses. The predicted load-displacement result is matched with experimental measurement results at the crack propagation region. Package delamination can be predicted by implementing the proposed testing and modeling scheme within the cohesive zone model.@en

Delamination of interfaces is known as one of the root causes of failure in microelectronic industry and therefore is getting more and more attention. In order to be able for judging the risk of the interface fracture, the critical fracture properties of the interfaces should be available i.e. Interfacial fracture toughness. Interfacial fracture toughness is highly dependent to temperature, moisture and mode mixity. This work deals with the fracture toughness measurements of an EMC-Cu lead frame interface under pressure cooker conditions ( >100 oC & 100% RH). To deal with it, a chamber with high pressure, i.e. pressure cooker or pressure vessel, is needed. A mixed mode bending setup is installed in the pressure chamber. This will make it possible to have a prescribed opening displacement under combined mode I/ II conditions on a bi-material specimen.@en