Glass frit bonding is an important technology for the hermetical encapsulation of microsensors. During manifactiring processes and in application the bonding layer is repeatedly exposed to temperature changes. Therefore a meaningful stability assessment must consider possible temperature dependent fracture toughness parameters. This work shows that the influence of temperature changes on the fracture toughness depends on whether the bonding layer is subjected to externally pure tensile or combined tensile and shear loading. The reasons for this effect are discussed by use of finite element simulations. Two different kinds of cracks are compared with regard to the residual stresses that result from the wafer bonding process. These residual stresses have a high influence on the loading conditions at the crack tip, when the crack is kinking into the glass frit material. However, the influence of residual stresses on an interfacial crack that propagates parallel to the plan e of the bonding layer is almost negligible

No abstract

No abstract

No abstract

AcknowledgmentsThe presented results be a part of the project "Investigations of a power module design for high thermal stress applications in automotive, aerospace and space -HiT -Modul". The project is founded by the federal ministry of research and education Germany and is a part of the program "Power Electronics for Energy Efficiency Enhancements". AbstractDAB are a new kind of substrates in which the copper layer was replaced by an aluminum layer. In [1] a increase of the roughness of these aluminum layer was observed during thermal cycling tests. A similar effect was observed during power cycling tests in [2,3]. This paper will discuss this effect with experimental results and Finite Element (FEM) simulations.