A printed circuit board (PCB), commonly called a printed wiring board (PWB) or etched wiring board, is a structure used to connect and support electronic components through conductive pathways. These pathways are etched from copper sheets that are laminated into a substrate that does not conduct the signal.
Multiple Layer PCB
Circuit boards are often composed of many layers and are called multi-layer PCBs. These layers, whether thin etched boards or trace layers, are bonded with lamination. The lamination process consists of placing the internal layers under extreme temperature (375 degrees Fahrenheit) and pressure (275 to 400 psi) while laminating with a photosensitive dry resist. The PCB is allowed to cure at a high temperature, the pressure is slowly released and then the material is slowly cooled.
Double-Sided PCBs
Though other aspects of manufacturing double-sided PCBs differ, the lamination process remains very similar. The PCB panel is laminated with a photosensitive dry resist under extreme temperature and pressure.
Sequential Lamination
Printed circuit boards can be comprised of two or more subsets if you use the sequential lamination technology. The subsets, multi-layer PCBs created in separate processes, are pressed together and a dielectric element is interposed among each pair of subsets. It is then subject to the standard manufacturing steps.
Teflon (PTFE) Microwave Laminates
PTFE microwave laminates are a type of laminate that has a very low electrical loss, consistent dielectric constant and tight thickness tolerance---all required for certain applications such as radio frequencies.
One common way of laminating PTFE laminates is with CTFE (chlorotrifluoroethylene) thermoplastic film. A pressure of 100 to 200 psi is maintained through the entire lamination process. It is heated until it reaches 400 degrees Fahrenheit, where it is cured, then is slowly cooled.
Lamination | Multi-layer PCB Manufacturing Process - 04
