Compression Force
Localized forces applied to individual layers, trace patterns, or embedded structures during the composite bonding process ensure proper adhesion and material flow. This localized stress, referred to as sub-component pressure, must be carefully controlled to prevent damage to delicate inner-layer copper traces and vias. If the applied force is too low, voids and dry spots form in the dielectric material, leading to delamination.
Conversely, excessive force can crush glass fibers or wash out copper traces. Maintaining the correct stress ensures the structural integrity of complex multi-layer boards.
Distribution Method
Hydraulic laminating presses use sacrificial padding and conformable release sheets to distribute the force evenly across the uneven copper circuit patterns. Because the copper traces stand proud of the dielectric base, the press must squeeze the resin into the gaps between the traces. This conformable layer translates the bulk press force into the required sub-component pressure at each point of the board.
Technicians monitor the pressure profile throughout the cure cycle to adapt to the changing viscosity of the resin.
Joint Integrity
Inadequate localized pressure results in weak resin-to-copper bonds that fail during subsequent thermal assembly processes. When the board is heated during solder reflow, trapped air pockets expand and tear the layers apart. Proper force control eliminates these internal voids and prevents layer separation under thermal stress.
