Investigation of wiring boards based on biopolymer substrates

The paper at hand engages the topic of the use of biopolymers in electrical engineering. While different articles on the functionalization of bio-based substrates by polymer thick film technique were published, only few dealt with the functionalization by metal foil lamination and subsequently etching. The latter is the research topic of the paper presented here. Bio-based substrates were functionalized by polymer thick film technique and foil lamination and subsequently etching. The surface roughness was assessed before and after the functionalization using 3D-light microscopy. Furthermore SMD-chips were mounted on the functionalized substrates using different techniques. The techniques were soldering and adhesive bonding. The joint between the substrate and the SMD-chips was evaluated with destructive shear force measurements. It could be shown, that metal foil laminated substrates get not as strong bonds as polymer thick film functionalized substrates, if adhesive bonding is used. However, the strongest bonds can be achieved by soldering. Additionally, the failure form was analysed and six failure types could be distinguished. The data seems to point to a connection between failure type and substrate/mounting technique combination.