Process Optimization of Injection Overmolding Structural Electronics with Regard to Film Distortion

Research output: Contribution to journalArticleResearchpeer-review

Authors

  • Behnam Madadnia
  • Jonas Groten
  • Jan Vanfleteren
  • Barbara Stadlober
  • Frederick Bossuyt
  • Jatinder Kaur

External Organisational units

  • Institute of Nanostructured Materials and Photonics, Joanneum Research
  • Department of Materials Science and Engineering, Ghent University
  • kdg Holding GmbH

Abstract

The integration of structural electronics in injection-molded parts is a challenging step. The films—comprising of laminated stacks with electronics—are exposed to shear stresses and elevated temperatures by the molten thermoplastic. Hence, molding settings have a significant impact on the successful, damage-free manufacturing of such parts. In this paper, test films with polycarbonate (PC) sheets as outer and two different thermoplastic polyurethanes (TPUs) as middle layers incorporating conductive tracks on a flexible printed circuit board (flexPCB) are manufactured and overmolded with PC. Parameter studies investigating the influence of the melt temperature, mold temperature, injection speed and used TPU layer were performed. The molded parts were inspected visually and compared with a numerical simulation using injection molding software. A shear distortion factor for the TPU layer was derived based on the simulations that linked the shear stresses with the injection time and the softening (melting) of the TPU. The distortion of the films was found to reduce with higher melt temperature, lower mold temperature and faster injection speed. Films using the TPU with the higher melting temperature yielded significantly better results. Moreover, distortion on the films reduced with the increasing distance to the gate and a larger cavity thickness was found to be beneficial. All those relations could be correlated with the shear distortion factor.

Details

Original languageEnglish
Article number5060
Number of pages20
JournalPolymers
Volume14.2022
Issue number23
DOIs
Publication statusPublished - 22 Nov 2022