There is a quite famous means for making decisions when there is not enough useful information or verifiable data. This technique is known as the SWAG method. However, because the results of using the method can be quite unpredictable, it is not the preferred approach for doing good engineering work. A more reliable strategy is to follow a scientific method that begins with a thorough understanding of the problem to be solved, followed by conducting research and implementing actions that have been validated experimentally.
A good example of following the scientific method is the utilization of your CM’s DFM and DFA rules and guidelines as constraints for your PCBA design choices. What about conveying these decisions to your CM? Often, the PCB Gerber file format—which has its advantages and disadvantages—is used. However, are there other design file options that may, in fact, be better?
The PCB Gerber File Format: Advantages and Disadvantages
Gerbers hold the distinction of being the first industry-wide format for PCB file packages. As such, the PCB Gerber file format has been long viewed as an industry standard and all manufacturers accept them. In addition to being first, Gerbers have other advantages, as listed below.
PCB Gerber File Advantages
- Include imagery
Gerbers can be represented as images for use in plotters, direct imagers and automatic optical inspection (AOI) equipment.
- Simple format
Gerbers are simple ASCII formatted files.
- Accepted by all manufacturers
Even manufacturers that prefer their own custom design file format will accept Gerber files.
PCB Gerber File Disadvantages
- Multiple files
Although the format is simple, several different files are required for the PCB Gerber file format package. For example, there is no component placement data, embedded netlist or drill hole data included in the Gerber file format. These require additional files.
- Prone to errors
The need to have multiple files aligned increases the opportunity for errors.
- Tend to slow the fabrication process
Gerbers do not transfer to fabrication as well as other formats.
As shown above, there are pros to using Gerbers. However, there are cons, as well. Fortunately, alternatives are available that successively address these shortcomings.
Other Options for PCB Design Files
Although Gerbers are included as an output option in virtually all PCBA design software packages, they have never been adopted by any recognized standards organization as being the preferred method for compiling or transferring design information, data and/or imagery. In fact, the premier standards organization for the PCB industry recognizes IPC-DPMX Digital Product Model Exchange, which is more commonly known as IPC-2581, as the standard for exchanging design data with your CM. IPC-2581 is inspired by OBD++ and compares favorably with Gerbers, as well as manufacturer custom CAD files.
|PCB DESIGN FILE OPTIONS|
|Attributes||Gerbers||Manufacturer Custom CAD||ODB++||IPC-2581|
|Can be used by most CMs||Yes||No||Yes||Yes|
|Easy to generate||Yes||No||Yes||Yes|
|Optimizes quote process||No||Yes||Yes||Yes|
|Promotes fast development||No||Yes||Yes||Yes|
1 Custom CAD files typically can only be generated using the manufacturer’s software.
2 Most major fabricators and assemblers are capable of utilizing the IPC-2581 standard due to an aggressive campaign by IPC to promote its utilization to improve innovation and reduce costs.
3 Although not all PCBA design packages can generate the IPC-2581 format, the best in the industry can.
3 PCB Manufacturing Trends You Need to Know
As the table above illustrates, the primary advantages of designers using the PCB Gerber file format hinge on familiarity. As for improving the PCBA development process, using a manufacturer’s custom format is probably a better option. The best alternative of all, however, is a generic CAD file format, such as IPC-2581, which is designed specifically to optimize board design, fabrication and assembly.
|Tempo's Custom PCB Manufacturing Service
At Tempo Automation, our goal is to help you design at the speed of innovation by building high-quality PCBAs for prototyping and low-volume production faster than anyone in the industry, whether you take advantage of the IPC-2581 standard or prefer Gerbers.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.