Printed Circuit Boards are crucial components that support various electrical components mechanically while also offering them electrical connection. The electrical connections occur via tracks or copper traces that technicians form on a laminated copper plate. However, to get to this part of production, fabricators must go through a couple of steps, including designing the PCB design.
After designing your PCB, your PCB contract manufacturer (CM) can create circuit boards that cater to your requirements according to the design. However, just like architectural designs, circuit board designs must be clear, precise, and accurate for the manufacturer to use them efficiently. Moreover, the design has to be followed by various documentation, which is also crucial to the development process. One of these documents is Gerber files which fabricators utilize to fabricate raw PCBs. But what exactly does Gerber File entail? Why are they crucial to the PCB production process? And why should you consider using them in your project?
A Clear Understanding of Gerber Files
Gerber files, generally, are Open ASCII Vector File formats that encompass info on every physical circuit board layer as portrayed by your PCB design. The Gerber files represent PCB objects such as silkscreen images, solder mask, pads, vias, and copper traces via draw code or flash and then defines them using vector coordinates. Manufacturers utilize Gerber files to efficiently translate the information contained in your design to physical Printed Circuit Board properties.
Printed Circuit Board designers typically generate Gerber files via PCB designing software, for example, CAD. However, even though all circuit board designing software programs do the same job, producing Gerber files, they utilize different steps and processes to get to the final product.
Today, most of the Gerber files you will find in the market are generated conforming to the current RS-274X Gerber file format, surpassing other obsolete formats, such as the RS-274-D standard.
Like other text files, Gerber files don’t have to bear a specific identifying name, however, some common Gerber extensions include:
Gerber File Processes
During the circuit board designing phase, Circuit Board designers typically zip the file into one file after developing the Gerber file and then send it to the PCB manufacturer. Sometimes the information package might entail multiple layers, but this depends on the following:
- The Printed Circuit Board’s stack-up
- Array layout
- Fabrication drawing
- Pick and place
- Drill programs
Each ground, power, copper circuitry, and artwork layer must correspond efficiently with the Gerber file for the manufacturer to generate the required circuit board pattern.
The PCB outermost layers, known as bottom and top, solder and component, will also bear conforming layers for silkscreen and solder mask application. Finally, the paste layers are generally provided for the purposes of assembly.
Moreover, the Gerber files also have programming information for drilling machinery. In some cases, these files might cater to more than one drill machine according to the type of PCB being manufactured. The drilling program provided by the Gerber file for every hole conforms to X and Y coordinates that relate to 0,0, as defined within the fabrication drawing. In most cases, we define plate through-holes, buried and blind vias, slots, and non-plated holes in different Gerber files. In addition, the files should entail the board’s outline describing the machining profile to be manufactured and any cutouts (internal) that technicians have to make. Often included inside the Readme.txt file is information concerning the purpose of the files above.
Gerber File Formats
The RS274X file format has been in use since 1998, and it is a revised version of the RS274-D format, which utilizes data, unit, and embedded format information. The complex apertures that define the PCB layer are embedded, allowing for custom apertures and standard sizes. Moreover, this file format lets designers use polarity control, polygon fill commands, multi-layer structures for single layers, film control, et cetera. Moreover, this improved version eliminates manual information entry and reduces photo plotting errors.
RS274-D is the oldest Gerber file format designed by Gerber file scientists. Moreover, you present this file using NC (Numerical Control) and is compatible with varying photo plotters. However, due to a couple of drawbacks regarding RS274-D as per user interpretation and the input of data manually, scientists have come up with newer file formats that are more efficient.
The ODB++ file format was generated by valor, and it is a standardized, self-extracting, and all-inclusive input format that automates the following processes:
- Drill placement
- Stack up
Initially, ODB++ wasn’t user-friendly; however, this file format is now easy to utilize through multiple updates. Moreover, you can also use ODB++ as input by CAD programs.
Gerber X2 is the most recent Gerber file format in the market today, and it is made for advanced CAM PCB software apps. Some examples of attributes that designers can apply when working with this Gerber file include:
- Pad function (fiducial, VIA Pad, SMD, etc.)
- Parts represented by the file (coupon, an array, single PCB, etc.)
- The function of files (top copper, top mask, etc)
Moreover, this format is compatible with the original Gerber X1 format, which lets designers quickly transfer valuable PCB design information between these file formats.
Benefits of Gerber Files
They Include Imagery
We can present Gerber files in the form of images for utilization in direct imagers, auto-optical inspection machines, and plotters.
All Gerber file formats are simple ASCII format files. Therefore, most manufacturers can work with them without using a lot of resources.
Accepted by Multiple Manufacturers
Gerber files simplify PCB design translation; therefore, multiple manufacturers prefer to utilize this format in the design translation phase. Even manufacturers who have their custom designs also accept standard Gerber files.
Disadvantages of Gerber Files
Prone to Errors
Manufacturers require multiple Gerber files to translate circuit board designs effectively. However, the involvement of various files grows the odds of errors occurring.
Slows Down Fabrication the PCB Fabrication Process
Gerber files don’t transfer well during the fabrication process. Due to this reason, these files tend to slow down the fabrication process immensely.
Gerber files are crucial components that manufacturers should pay attention to during the PCB fabrication process. When utilized well, Gerber files have the potential to make the fabrication process smooth. Moreover, these files also reduce the chances of an error occurring during the production process by ensuring that the manufacturer perfectly matches the user requirement to the finished product.