Lamination Procedure
Controlled thermal and mechanical profile applications in a hydraulic press system fuse the individual layers of a multi-layer board together under a vacuum. A multi-stage vacuum press cycle regulates temperature, pressure and vacuum level over a period of several hours to cure the resin in the prepreg sheets. This process is executed at the core lamination stage of high-reliability PCB fabrication.
It establishes the final thickness and mechanical bond strength of the board.
Dynamic Profile
The cycle begins with a drawing of a deep vacuum inside the press chamber to remove air and volatile gasses from between the layer interfaces. Next, the platens are heated at a controlled ramp rate to melt the resin while a low kiss pressure is applied to hold the stack-up in place. Once the resin reaches its lowest viscosity point, the press ramps up to full pressure to compress the laminate and squeeze out excess resin.
The temperature is then held high to complete the curing reaction before a slow cooling phase begins. This slow cooling prevents the buildup of internal thermal stresses that would cause the panel to warp.
Laminate Quality
Strict control of each cycle stage ensures that the finished composite is free of internal voids and achieves a uniform thickness. This uniformity is necessary for maintaining consistent trace impedance across the entire active area of the board. High yields in multi-layer fabrication depend on this lamination repeatability.
