Adhesive bonding between multi-material assembly injection molding parts with an adhesive interlayer

摘要

As it offers a wide range of benefits, assembly injection molding of plastics represents an innovative technology. In a material, cost efficient and integrative process, the most diverse products for mechatronics applications can be manufactured. The technique can generate multi-material systems combining different parts with special functionality, e.g., plastics casings and circuit boards, in a fully automated process. This automated integration of part structure and functionality makes these products superior to others. However, it implies a great challenge in terms of technology for part development and production. Of vital importance for a media tight and durable connection between individual materials/parts of the assembly, are factors such as the components' compatibility and chemical-physical adhesion. Thermal stress in hybrid assemblies due to different thermal expansion coefficients is often the reason for part failure. An approach to meeting these challenges is the investigation of the process-integrated application of functional interlayers, in order to improve the formation of adhesion along with the optimization of the stress distribution. The following article will present findings obtained on the bond strength generated by different types of interlayers (hot-melt and pressure-sensitive adhesives) between circuit cards and different types of casing plastics. A fundamental understanding of underlying effects and the tools for predicting process dependent effects is required for the optimization of the systems' functionality. For this purpose, the interactions between material, system design and process conditions are considered in relation to bond strength.