PCB fabrication may seem simple, but it isn’t always the case. One thing that should not be overlooked is the accuracy in the manufacturing process, which is a major role of the designing process of PCB’s. The design should be exactly pictured and made according to the client’s specifications. These board specifications include the number of layers, the type of materials, the dimensions, and the number and circumference of holes. These are all put in a design, and a single mistake will make a nonfunctional or rejected PCB.
Designing and prototyping of the schematics are the initial steps in PCB fabrication.
These are the key steps to produce or prevent inaccuracies in the further stages of producing PCBs. During the initial phase, to create a physical version of the electronic schematic, a net list file is necessary. The sketch version or layout details are transferred to a Gerber, which is still commonly used, however there are other available EDA – Electronic Design Automation software tools.
Gerber file format isn’t that accurate as some poor manufacturers perceive, but this format is the foundation in manufacturing PCBs. The Gerber file contains alphanumeric characters and symbols. The new standard for Gerber files allows just one file to contain the majority of information, while the old standard requires more than a single file for containing the information for a layer. The advantage of the new standard over the old standard is that a single file is easy to keep track with than two or more files.
Gerber files’ instructions are used in the configuration parameters such that their codes include the suitable and desired geometry in the PCB fabrication process. They also include the specifications about the polygon fills, line widths, complex shapes, lettering and other parameters. Gerber files make possible the generation of codes, which have corresponding results in the physical layout of PCB’s.
Gerber files are not just limited to codes but they also show an image of the copper’s location on a layer, of where it should be. Gerber files also show images of where the solder mask and screen paint should be applied. They also contain information about the size, locations and properties of holes, which are in the form of codes. Excellon is another computer program that can help further with the layout concerning the specific drilling and routing places on the board.
Gerber files include the layouts of the top, bottom, silkscreen top, drill and board outline layer. Basically a Gerber file defines what needs to be done on each layer, including milling, drilling and cutting the layer of the board. However, the CAM technicians must continuously update the computer system so that there will be no discrepancies between the designing and manufacturing process in PCB fabrication.
After Gerber files are checked, along with the machine for prototyping, they are used for the creation of the PCB substrate. As part of completing the board, components are soldered into place. It is important that all traces are routed.
There are differences among the PCB manufacturers regarding the various processes that involve the designing and prototyping of PCB’s. Some have more advanced PCB software and a checklist online in which the client has the direct access to input the specifications and quantities of the PCB they need. The check file can be loaded directly to the design software. Other manufacturers use EAGLE or Easily Applicable Graphic Layout Editor, which is easier to use because of its schematic capture and PCB layout editor. There is a variety of free software that the manufacturers can choose from to assure them of ease during the initial phases of the PCB fabrication process.