PCB Manufacturing

Gerber files are generated for manufacturing.

Manufacturing

PCB manufacturing consists of many steps.

PCB CAM

Manufacturing starts from the fabrication data generated by computer aided design, and component information. The fabrication data is read into the CAM (Computer Aided Manufacturing) software. CAM performs the following functions:

Input of the fabrication data.

Verification of the data

Compensation for deviations in the manufacturing processes (e.g. scaling to compensate for distortions during lamination)

Panelization

Output of the digital tools (copper patterns, drill files, inspection, and others)

Panelization

Several small printed circuit boards can be grouped together for processing as a panel. A panel consisting of a design duplicated n-times is also called an n-panel, whereas a multi-panel combines several different design onto a single panel. The outer tooling strip often includes tooling holes, a set of panel fiducials, a test coupon, and may include hatched copper pour or similar patterns for even copper distribution over the whole panel in order to avoid bending. The assemblers often mount components on panels rather than single PCBs because this is efficient.

The panel is eventually broken into individual PCBs along perforations or grooves in the panel.[28] Today depaneling is often done by lasers which cut the board with no contact. Laser depaneling reduces stress on the fragile circuits, improving the yield of defect-free units.

Copper patterning

The first step is to replicate the pattern in the fabricator's CAM system on a protective mask on the copper foil PCB layers. Subsequent etching removes the unwanted copper. (Alternatively, a conductive ink can be ink-jetted on a blank (non-conductive) board. This technique is also used in the manufacture of hybrid circuits.)

Silk screen printing uses etch-resistant inks to create the protective mask.

Photoengraving uses a photomask and developer to selectively remove a UV-sensitive photoresist coating and thus create a photoresist mask. Direct imaging techniques are sometimes used for high-resolution requirements. Experiments were made with thermal resist.[29]

PCB milling uses a two or three-axis mechanical milling system to mill away the copper foil from the substrate. A PCB milling machine (referred to as a 'PCB Prototyper') operates in a similar way to a plotter, receiving commands from the host software that control the position of the milling head in the x, y, and (if relevant) z axis.

Laser resist ablation Spray black paint onto copper clad laminate, place into CNC laser plotter. The laser raster-scans the PCB and ablates (vaporizes) the paint where no resist is wanted. (Note: laser copper ablation is rarely used and is considered experimental.[clarification needed])

Laser etching The copper may be removed directly by a CNC laser. Like PCB milling above this is used mainly for prototyping.

The method chosen depends on the number of boards to be produced and the required resolution.