High Power RF electronics is one of the essential parts for wireless communication, including the personal communication, broadcasting, microwave radar, etc. Moreover, high efficient high power electronics has entered the ISM market, such as the power generator of microwave oven.@en

The present study deals with experimental investigation of the delamination toughness of EMC (epoxy molding compound) and Copper-leadframe interfaces. Test samples were directly obtained from the production line. EMC is attached on copper substrates with various surface treatments. Mixed mode bending experiments were performed under various temperature and moisture environments. The test procedure and some results were reported previously in ECTC08 and ECTC09 [1-2]. Recently, we studied the effect of delaminated surfaces in order to get better understanding of the established fracture toughness. Therefore, after the delamination experiments, some of the delaminated samples were subjected to various surface analyses (SEM, FIB, EDX). Two types of failure patterns are found depending on the loading mode mixture, and the environmental conditions. Firstly, depending on the type of copper surface treatment, pure interface delamination is observed for some of the interfaces. Here, we observed clean delaminated copper surfaces. The second type of failure is a combination of interface delamination and compound cracking. Here, it is found that after the separation of interfaces, some EMC remains on the copper surface. In this case the experiment results showed that the interface delamination and molding compound cracking combined failure occurs at relatively high force values.@en

Microelectronic packages can be considered as composite structures fabricated from highly dissimilar materials. Interface delamination related failure often occurs when the packaged devices are subjected to thermo-mechanical loading. The analysis of delamination of a laminate structure with a crack along the interface is central to the characterization of interfacial toughness. Due to the mismatch in thermal mechanical properties of the materials adjacent to the interface and also possible asymmetry of loading and geometry, usually the crack propagates under mixed mode conditions. In this paper, the interface toughness of epoxy molding compound - copper interface in IC packages is characterized. The test specimen is directly obtained from a production process line. A small-size multi-functional mixed mode bending (MMB) tool was designed and fabricated. For measurements under various temperatures and moisture conditions, a special climate chamber is designed. The ¿current crack length¿ is required for the interpretation of measurement results through FEM-fracture mechanics simulations. Therefore, during testing the ¿current crack length¿ is captured using a CCD camera. The critical fracture properties are obtained by interpreting the experimental results through finite element modeling. As input parameters, the material properties are both experimentally and numerically characterized as functions of temperature and moisture. In order to get more accurate interfacial toughness, the influence of residual stresses in the sample is considered.@en

As we face higher numbers of material layers in the increasingly complex Microsystems, the rating of layers reliability has to keep pace. Fracture mechanical descriptions are a big qualitative improvement when using simulation for design and reliability support, especially when looking at layer delamination. In order to simulate the interfacial fracture we urgently need to find empirical parameters, because the fracture parameters have to be verified as critical. Such experiments are difficult to carry out at the Silicon-to-Epoxy Molding Compound (EMC) interface. We are now able to do such investigations using the Mixed Mode Chisel (MMC) setup. In this paper we compare results of the Silicon-EMC interface for the in- and exclusion of thermal residual stresses in the simulations. The interface specimens are of package scale and are derived from the embedded wafer level molding process. We find the impact of thermal residual stresses crucial for the validity of fracture toughness values, and show relations to consider when using the MMC setup. We do not find any EMC residuals on the delaminated Silicon surface.@en

Interfacial delamination has become one of the key reliability issues in the microelectronics of portable devices 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 interfacial toughness. Due to the mismatch in mechanical properties of the materials adjacent to the interface and also possible asymmetry of loading and geometry, usually the delamination propagates under mixed mode conditions. In this study, a modified mixed mode bending test using production line interface samples is proposed. The critical fracture properties are obtained by interpreting the experimental results through dedicated finite element modeling. The interface types being considered in the present work are between EMC's and copper lead frame. Keywords-fracture; delamination; testing@en

An ongoing root cause of failure in microelectronic industry is interface delamination. In order to explore the risk of interface damage, FE simulations for the fabrication steps as well as for the testing conditions are generally made in the design stage.@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 interfacial toughness. Due to the mismatch in mechanical properties of the materials adjacent to the interface and also possible asymmetry of loading and geometry, usually the crack propagates under mixed mode conditions. 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. As a consequence the specimen dimensions are relatively small and therefore a dedicated small-size test set-up was designed and fabricated. The test set-up allows transferring two separated loadings (mode I and mode II) on a single specimen. The set-up is flexible and adjustable for measuring specimens with various dimensions. For measurements under various temperatures and moisture conditions, a special climate chamber is designed. The "current crack length" is required for the interpretation of measurement results through FEM-fracture mechanics simulations. Therefore, during testing the "current crack length" is captured using a CCD camera and a micro deformation analysis system (MicroDac). The critical fracture properties are obtained by interpreting the experimental results through dedicated finite element modeling.@en

Warpage is a critical issue for a QFN panel molding process. Much work was done in the past to predict the warpage of a package during cooling down from molding temperature. However, until now, warpage could not always be predicted well, even if the viscoelastic behavior of the molding compound is taken into account. It was for example observed that the cooling velocity affected the warpage after cooling down. Because of this reason, the mechanical behavior of the molding compound was investigated in more detail. In this research, the mechanical properties of the molding compound are determined. It turned out that the properties are highly dependent on time and temperature. A complete viscoelastic model of the model compound is achieved by combining DMA and dilatometric test results. The model is implemented in the finite element software ABAQUS. In this study, our advanced model is compared with elastic calculations which are normally done. A validation experiment is performed in which simulation results are compared with experimental warpage data of a double layered beam, consisting of a layer of molding compound and a layer of silicon. This beam is cooled down from a temperature above Tg to room temperature with different cooling rates. In the meantime warpage is measured and compared to simulation results. Finally, the advanced material model is used for calculations on a QFN-panel.@en