PCB fabrication technology includes computer-aided manufacturing and processing techniques, such as CAD/CAM, as well as photoplotting technology. Below, we’ll take a closer look at computer-aided manufacturing and processing techniques.
Computer-Aided Manufacturing (CAM) involves performing various process operations according to the specified manufacturing procedures. Before photoplotting begins, all previously discussed process requirements must be carefully prepared. For instance, tasks such as mirroring, solder mask expansion, process lines, process frames, linewidth adjustments, center hole creation, and outline shaping are all handled during the CAM stage. It’s especially important to address cases where the spacing between user-defined features is too narrow, ensuring these areas are properly managed. Since each manufacturer follows a unique production process and maintains varying levels of technical expertise, achieving the customer’s final specifications often requires making tailored adjustments during the CAM process—whether in terms of precision or other critical factors. As a result, CAM processing has become an indispensable step in modern printed circuit board manufacturing.
The work completed by CAM
1. Correction of pad sizes, merging D-codes.
2. Correction of line width, merging D-code.
3. Check the minimum spacing between pads, between pads and traces, and between traces themselves.
4. Check and combine the aperture sizes.
5. Check for the minimum line width.
6. Determine the solder mask expansion parameters.
7. Perform mirroring.
8. Add various process lines and process boxes.
9. Perform linewidth correction to mitigate side etching.
⒑ Form a center hole.
⒒ Add outline corner lines.
⒓ Add positioning holes.
⒔ Layout, rotate, mirror.
⒕ Patchwork.
⒖ Overlay processing of graphics, including chamfer and tangent treatments.
⒗ Add user trademark.
Organization of the CAM Process
Since there are dozens of popular CAD software options available on the market, managing CAD processes must first begin with organizational measures—after all, effective organization can help achieve twice the results with half the effort.
Since the Gerber data format has become the industry standard for photoplotting, Gerber data should be used as the primary object throughout the entire photoplotting process. Using CAD data instead would lead to the following issues.
1. There are too many types of CAD software available. If every process requirement must be handled within a single CAD program, it would mean that each operator would need to become proficient in mastering the operation of *every* CAD software. This, in turn, would necessitate an extensive training period—long enough to turn operators into skilled professionals capable of meeting real-world production demands.
This is not cost-effective, either in terms of time or money.
2. Due to the numerous process requirements, some of them simply cannot be met by certain CAD software. This is because CAD software is primarily designed for drafting and design purposes, without accounting for the specialized needs inherent in manufacturing processes, making it impossible to fulfill all requirements. In contrast, CAM software is specifically tailored for handling manufacturing processes.
These are exactly what I do best.
3. The CAM software is powerful, but it only works with Getber files and cannot handle CAD files at all.
4. If CAD is used for process planning, it requires each operator to have access to all CAD software packages, and each software package also comes with its own specific process requirements. This would introduce unnecessary complexity into management.
In summary, CAM organizations should have the following structure—particularly in large and medium-sized enterprises.
⑴ All process operations are uniformly performed using Gerber data as the processing target.
⑵ Each operator must master the skill of converting CAD data into Gerber data.
⑶ Each operator must master the operation methods of one or more CAM software programs.
⑷ Establish unified process specifications for Gerber data files.
The CAM process can be handled more efficiently by having several operators work together in a coordinated manner. A well-organized structure will significantly enhance management and production efficiency, while also effectively reducing error rates—and ultimately improving product quality.