TY - THES

T1 - Influence of Process Parameters on Interfacial Adhesion, Mechanical and Thermomechanical Properties of Glass Fiber Reinforced Epoxy Resin in Printed Circuit Boards

AU - Obwaller, Rene

N1 - embargoed until 30-09-2029

PY - 2024

Y1 - 2024

N2 - In this work, the effects of the press process during manufacturing of printed circuit boards (PCBs) on the fracture toughness as well as the mechanical and thermo-mechanical performance of the dielectric layers of PCBs are experimentally determined using a statistical design of experiments (DoE). Strong interfacial adhesion in PCBs, for example, is crucial for ensuring long-term reliability, as it prevents delamination and mechanical failures under various operating conditions. The results should provide valuable insights into optimizing the press profiles to enhance material characteristics and layer-to-layer adhesion, thereby improving the overall performance and durability of the PCBs. Kinetic curing modeling and rheological characterization were used to define the process parameters, followed by establishing a DoE that offers a statistical evaluation of the factors and interactions between the different material properties. Mechanical and thermo-mechanical performance was characterized using conventional methods like tensile test, dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA), while the bonding strength was assessed by a fracture-mechanical approach based on the double cantilever beam (DCB) test. The results from the factorial design showed that mechanical and thermo-mechanical properties did not show significant deviations that can be described by the varying process parameters. The fracture toughness, on the other hand, was definitely influenced by the press process, resulting in three different types of fracture behavior. The statistical evaluation showed that the fracture toughness is impacted, besides by the pressure, holding temperature and time, primarily by the applied heating rate, resulting in a weakening of the interface with increasing heating rates. Eventually, the gained information about the influence of the press process can be used to find material specific optimum parameter sets during pressing that can enhance interfacial adhesion of the layers within.

AB - In this work, the effects of the press process during manufacturing of printed circuit boards (PCBs) on the fracture toughness as well as the mechanical and thermo-mechanical performance of the dielectric layers of PCBs are experimentally determined using a statistical design of experiments (DoE). Strong interfacial adhesion in PCBs, for example, is crucial for ensuring long-term reliability, as it prevents delamination and mechanical failures under various operating conditions. The results should provide valuable insights into optimizing the press profiles to enhance material characteristics and layer-to-layer adhesion, thereby improving the overall performance and durability of the PCBs. Kinetic curing modeling and rheological characterization were used to define the process parameters, followed by establishing a DoE that offers a statistical evaluation of the factors and interactions between the different material properties. Mechanical and thermo-mechanical performance was characterized using conventional methods like tensile test, dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA), while the bonding strength was assessed by a fracture-mechanical approach based on the double cantilever beam (DCB) test. The results from the factorial design showed that mechanical and thermo-mechanical properties did not show significant deviations that can be described by the varying process parameters. The fracture toughness, on the other hand, was definitely influenced by the press process, resulting in three different types of fracture behavior. The statistical evaluation showed that the fracture toughness is impacted, besides by the pressure, holding temperature and time, primarily by the applied heating rate, resulting in a weakening of the interface with increasing heating rates. Eventually, the gained information about the influence of the press process can be used to find material specific optimum parameter sets during pressing that can enhance interfacial adhesion of the layers within.

KW - Design of Experiment

KW - PCB

KW - Composites

KW - Prepreg

KW - Model Free Kinetics

KW - Fracture Mechanics

KW - Statistische Versuchsplanung

KW - Leiterplatten

KW - Verbundwerkstoffe

KW - Prepregs

KW - Modellfreie Kinetic

KW - Bruchmechanik

M3 - Master's Thesis

ER -