Functionalized Compounds for Micro‐Injection Molded Piezo Modules (μIMP‐Modules) and Their Electrical Contacting
Multi‐component micro‐injection molding enables the manufacturing of active elements as well as electrical contacting in situ and in a single process by using piezo active and electroconductive plastic compounds. Each compound is functionalized with filler materials according to its special demands. To this end, polypropylene (PP) with an electromechanical active filler based on piezoceramic powder (PZT: Lead zirconate titanate) for sensor functionality as well as PP with electroconductive properties based on carbon nanotubes (CNT) and carbon black (CB) for electrical contacting are investigated. Therefore, different compound compositions are analyzed with regard to their mechanical and electrical properties as well as their mechanical compatibility. For the analyses, micro injection molded samples of the different compounds are used. Furthermore, investigations on composite strength are conducted by measuring interlaminar shear strength between the functionalized compounds. Based on the material characterization, a simulation of the thermomechanical behavior is done and the process‐related residual stresses are analyzed. To achieve the prerequisites for fabricating sensor modules in mass production, the functionalized compounds should be processed by means of the two‐component micro‐injection molding technology. According to this, the objective target is a large‐scale integration of these piezo modules into multifunctional lightweight structures. Therefore, the modules are combined with electrically functionalized textile substrates creating semi‐finished products with sensor functionalities. The mechanical and electrical connections are created by ultrasonic welding. Applying this technology requires a manufacturing study with varying process parameters of joining force, amplitude and welding time with the aim of achieving minimal electrical contact resistance.