Most engineers are accustomed to sending their PCB design files directly to high-frequency board manufacturers for production. However, the more common practice internationally is to convert PCB files into GERBER files and drilling data before handing them over to high-frequency board manufacturers. Why this extra step?
This is because electronic engineers and PCB engineers may have different understandings of the circuit board. The GERBER files generated by high-frequency board manufacturers might not match your requirements. For instance, if you define component parameters in your PCB design but don't want them to appear on the final product, and you haven't specified this, the manufacturer might inadvertently leave those parameters on the PCB. This is just one example. By converting the PCB files to GERBER files yourself, you can avoid such situations.
GERBER files are internationally standardized photoplot format files. They encompass two formats: RS-274-D and RS-274-X. RS-274-D is the basic GERBER format, which requires the accompanying D-code file to fully describe a graphic. RS-274-X is the extended GERBER format, which includes D-code information within itself. Common CAD software can generate both of these file formats.
Gerber File Extensions and Meanings:
GTL: Top Layer
GBL: Bottom Layer
GTO: Top Overlay (Top Silk Screen)
GBO: Bottom Overlay (Bottom Silk Screen)
GTP: Top Paste (for SMT Stencils)
GBP: Bottom Paste
GTS: Top Solder Mask (also called Solder Resist or Green Solder Mask, negative)
GBS: Bottom Solder Mask
G1: Midlayer 1 (Inner Layer 1)
G2: Midlayer 2 (Inner Layer 2)
GP1: Inner Plane 1 (Negative Plane 1)
GP2:Inner Plane 2 (Negative Plane 2)
...
GM1: Mechanical 1
GM2: Mechanical 2
...
GKO: Keep Out Layer (Restrictive Layer)
GG1: Drill Guiding Layer
GD1: Drill Drawing Layer
GPT: Top Pad Master (Top Solder Pad)
GPB: Bottom Pad Master (Bottom Solder Pad)
These additional Gerber file extensions represent various internal layers, mechanical layers, and additional components or information in a printed circuit board (PCB) design.
