PCB file introduction

PCB is a common circuit product in our life. In the electronic design industry, the final file of embedded product are also PCB documents.

A PCB project generally contains four files: xxx.SchDoc (PCB schematic diagram), xxx.PcbDoc (PCB package diagram), xxx.SchLib (PCB schematic library), and xxx.PcbLib (PCB package library).

The general process is as follows: first draw [PCB schematic library SchLib], then draw [PCB packaging library PcbLib], and associate schematic library components with packaging library.

Then draw the [PCB schematic diagram SchDoc], update it to the [PCB package diagram PcbDoc], Design ->update PCB Document, and finally layout copper.

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    Introduction to Gerber files

    Why use Gerber? Gerber, also known as photo file, is a standard file format. Gerber consists of two important parts,Gerber photo file,which is used to describe the contents of one layer (a bit similar to film),and NC Drill hole file.

    PCB factories can directly produce the final PCB through Gerber. At present, the commonly used format is RS-274X, and most of the board factories also support the latest Gerber X2 format (with more stacking information and attributes of boards). Many engineers like to send PCB design documents directly to the board factory. In fact, this “lazy” approach is risky. Because the board factory ultimately needs to convert the PCB file to Gerber for production, there are many potential problems in the process from PCB to Gerber.

    Due to the problem of EDA tool version, the PCB file opened by the board factory may have changed.

    Due to lack of communication, some parameters on the PCB that do not need to be displayed are also left on the finished product.

    In a word, the process of converting PCB to Gerber is not necessarily the same as copy, and designers should be responsible for this process. Therefore, most experienced engineers will convert PCB into Gerber by hand, and then check whether Gerber has problems through software such as CAM350, and then send it to the board factory for processing. In addition, whether you use Altium, Allegro or Expedition, as long as you convert to Gerber, the board factory can correctly identify. Another point is that it is difficult to reverse generate PCB from Gerber. For the sake of safety, enterprises are not willing to send the design source file directly to the board factory.

    PCB gerber file normally include outline, CNC(plated & non-plated), silkscreen layer, solder mask layer, copper layer, solder paste layer as below:

    How to identify correct Gerber files

    The layout file consist of D-code and coordinates file. If there is no D-code, the trace will have no width, and the pad will have only outline; If there are no coordinates, there will be no graphics outline and board size; Ordinarily, the coordinate file will reflect the layout file, while the D-code file sometimes exists separately. At this time, we need to recognize these D-codes separately. If the software cannot recognize them, our engineers have to manually enter the D-code and send to customer to confirm whether the GERBER file is correct or not.

    About CNC file, normally, including DDR file and drill file, in DDR file, there are hole size,count and plated or not just like below

    About drill file,normally, its format is usually shown by “TXT” format,It is mainly used to provide the coordinate file required by the NC drill in production for the drill, indicating the drill to drill at the marked position of the program, and completing the process of PCB drilling, So, it start with M48,meanwhile,define drill file format(3:3 or 4:3),Units and Zero Suppression information, let us take a sample below,one sample P/N:20002131C below,

    Origin of PCB file suffix

    There are many EDA tools for PCB design, and the file format of PCB corresponding to each software is different. 

    Specific steps for opening PCB file


    Because the pcb file is drawn with professional software, it can be opened with this kind of software, such as the widely known Protel software


    It can also be opened with Altium software, which is the latest version of protel software


    We can also select the PADS software that is also easy to use as below. Pads software for high-end circuit design.


     The software described above is the software for design PCB files.

    Common gerber file to pcb file

    Method 1: 1. Directly export Gerber files to DXF format: Note: you need to select a lower version of DXF format. 2. Create a blank PCB and then import it:

    Method 2: 1. Create a Gerber file 2. Perform the quick import action, import the Gerber file of each layer, as well as the NC Drill file. In addition, if you want to obtain the accurate network name, the IPC-D-356 file must also be imported together. 3. After all files are imported, then:

    How to use Altium designer to reverse the Gerber file to generate PCB graphics and text!
    Convert Gerber files to PCBs. The common one is Cam350. Now it can be realized by using altium designer to reverse Gerber files to PCBs.
    Create a new CAM file.
    Open Altium designer14.2 software, File — New — Cam document.

    Tool — Netlist — extract, extract the network of the imported Gerber file (treat the connected tracks as the same network, and the network name is randomly generated). If you do not import the network table, you cannot generate PCB files.

    File — Export — Export to PCB to export CAM files to PCB. If the network table is not generated in the previous step, PCB export cannot be realized.

    PCB file transfer to GERBER

    Pcb file generation gerber file requires two steps: 1. generation of GERBER 2. generation of NC drilling file Run Altium Designer file, select Menu – File – Open the required PcbDoc file1. Select Menu – File – Enter Gerber file

    About CNC file, The summary is to set the English or metric units (inch English milimeters metric system) and precision. The format is 4:4 or 4:3. Generally, the metric system is 4:4

    DXF file transfer to GERBERUsing software cam350, it will be easy to transfer DXF file to Gerber, file- import -choosing DXF(Note,if ODB++ file from genesis2000 software, it can be recognized as well)

    File — Export — Export to PCB to export CAM files to PCB. If the network table is not generated in the previous step, PCB export cannot be realized.

    Finally, the file conversion between different software may hide certain hidden dangers, such as the recognition of special shaped pads, which need to be compared or confirmed with the original file. At the same time, it is necessary to realize that all software is not universal and has its use limitations.

    Ancient Chinese proverb: Caution makes a ship of ten thousand years old!

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