Application of Friction Riveting technique for the assembly of electronic components on printed circuit boards (PCB)

Abstract

Abstract The Friction Riveting process has shown promising feasibility for a variety of material combinations and applications in the transportation industry. Recent research has explored the potential application of this technique in electronics, specifically for the assembly of printed circuit boards (PCBs), using AA-2024-T3 rivets on thin glass-fiber-reinforced epoxy substrates. Considering these promising results, this study focuses on the effects of reducing the diameter of the rivets used in Friction Riveting because of the need for downscaling when joining assemblies on a smaller scale. Therefore, the joint formation of joints produced with PCBs was investigated in terms of process temperature evolution, microstructural changes, and mechanical properties. Joints were obtained at process temperatures ranging from 285 ºC to 368 ºC. Notably, the use of 4 mm rivets resulted in extensive delamination, weak joint mechanisms, and cracking. These issues were impaired by the different coefficients of thermal expansion of the materials involved. However, reducing the rivet diameter to 3 mm significantly improved the joint quality. Although a further reduction to 2.5 mm rivet diameter minimized delamination, it led to insufficient anchorage and cracking. Overall, joints produced with a 3 mm rivet diameter achieved the highest ultimate tensile force (UTF) of 276 N. This study lays the foundation for applying the Friction Riveting process to practical PCB assemblies. It demonstrates that it is possible to achieve a balance between sufficient rivet anchoring, minimized delamination, and reduced cracking by optimizing the process parameters to the diameter-to-thickness ratio. Further joint optimization can be deduced from this study by potentially using rivets with lower plasticizing temperatures and selecting PCBs with improved heat resistance. In summary, this research highlights the prospect of Friction Riveting as an innovative method for PCB assembly, demonstrating the critical role of temperature control and rivet diameter in ensuring robust joint formation and performance.