Structural Synthesis
Substrate manufacturing relies on a high-temperature pressing step to bond copper foils and prepreg sheets into a rigid base. This consolidation occurs during core lamination under controlled temperature profiles to cure the epoxy resin. This step secures the internal registration of copper traces before drilling.
Lamination Cycle
Processing begins with a vacuum drawdown to remove air and volatiles from the stack of materials. Thermosetting prepreg undergoes a transition from solid to liquid as the press platen temperature rises. This fluid phase allows the resin to fill the gaps between the copper traces on the inner layers.
High pressure is maintained while the resin polymerizes and cures, forming a permanent crosslinked structure. Cooling is performed under pressure to prevent copper delamination or board warpage.
Defect Prevention
Insufficient heating or inadequate hydraulic pressure can lead to incomplete curing of the thermosetting sheets. When the resin fails to crosslink completely, the mechanical strength and dielectric properties of the composite board are degraded. Voids can form in areas of low resin flow, resulting in localized moisture entrapment.
Delamination often becomes apparent during solder reflow or thermal shock testing. Verifying the cure state through thermal analysis prevents assemblies from failing in the field.
