PCB PRODUCTION PROCESS
Making A Multi-Layer PCB
DESIGN REVIEW AND PREPARATION OF PRODUCTION TOOLS.
The first stage in the manufacturing process involves a review of the manufacturing data package that is provided by the designer and preparation of the manufacturing tools and CAM data.
Production data package
The output of the PCB design is a data package provided to the manufacturer in an industry standard format – Extended Gerber or ODB++. The Gerber files define the copper layers, solder mask layers, component notations. In addition, the manufacturing data package includes a drill file, netlist and general specifications.
Once all the engineering questions have been resolved the necessary tools for production will be prepared.
Preparation of the manufacturing panels.
Manufacturers use standard manufacturing panels. The manufacturing panel has to be designed to maximize material usage, considering the PCB dimensions and manufacturing requirements: process control coupons, tooling holes and handling.
Working film (photo tools) preparation.
Using a laser plotter, a film is created for each PCB layer. The laser plotter is in a temperature and humidity controlled dark room. The films are registered with each other to assure perfect alignment between the layers. The punched registry holes are used later to align the films in the UV exposure process. Another method is using laser direct imaging (LDI), using a CCD camera in the exposure machine in order to register the phototool.