As PCB gets unavoidably scrapped in the actual production process, the factory needs to add an additional proportion of materials to ensure the required quantity of good boards. The additional proportion should take into account the number of layers, copper thickness, trace width, trace spacing, surface finish, special processes and so on. In general, the more difficult the processes are, the more additional materials are needed. The next step after feeding is sheet material cutting that involves in two stages.
PCB production starts with a large piece of sheet material. Due to the limitations of PCB production equipment and manufacture capabilities, the factory has requirements for its minimum and maximum processing size. Therefore, under the guidance of manufacture instruction (MI), the raw material of PCB (Copper Clad Laminate) needs to be cut into the processing size by automatic cutting machine before production. (Copper Clad Laminate, short for CCL, is a type of material made of electronic glass fiber cloth or other reinforcing materials dipped in resin, laminated with copper foil on one or both sides and heat pressed.). In order to maximize the utilization of CCL, manufacturers design PCB panelization in advance and get the appropriate processing size. While cutting, size of panelized boards, PCB thickness, sheet material types, copper thickness, and spacing between components and the edge of the board are all factors to be considered.
After cutting, those sheet materials cannot be directly used for image transfer, they need to be grinded and baked. The corners of the boards will be rounded and edged to remove the glass fibers left at the edge of the board during cutting to reduce scratch issues on the board surface or other hidden quality problems. At the same time, the moisture and organic volatiles are removed by baking to increase the dimensional stability and mechanical strength of the materials.
Once all the raw materials for PCB production have been processed, the image transfer process is now about to begin.
Check Pre-engineering | Multi-layer PCB Production Process 01 for previous process.
