What is the Gerber file in PCB?

This paper mainly tells what is the Gerber file in PCB.

Gerber file is a standard format used in electronic design automation (EDA), especially in the design and manufacturing process of printed circuit board (PCB), to transmit information such as circuit layer, pad, routing and component layout. It plays a vital role in all aspects of PCB manufacturing, helping manufacturers to obtain accurate production information from design documents. The following is a detailed explanation of the Gerber file, which is explained step by step:

1. The basic concept of GERBER file

Gerber file is a standard format for transmitting the manufacturing patterns of electronic equipment, which is mainly used in PCB manufacturing to describe the design information of each level on the circuit board, such as copper layer, pad, solder mask layer, screen printing layer and so on. Gerber files can be generated by various CAD tools, which is an important bridge from design stage to production stage.

2. Structure of Gerber file

Gerber files usually contain multiple files, each of which describes a specific layer of PCB. Mainly includes:

Copper Layers: describe the electrical connection parts of PCB, including signal layer, power layer, etc.

Solder Mask Layer: defines which areas should be soldered and which areas can be soldered.

Silkscreen Layer: used to display component logos, words and other identification marks.

Drill Layer: indicates where holes need to be punched in PCB, including component pin holes and test holes.

Component Placement Layer: indicates the placement position and direction of components.

3. The format of Gerber file

Gerber files are in a format similar to vector graphics, and each file contains the path description of PCB layers. Common Gerber file formats are:

RS-274X: A commonly used Gerber file format, which uses an "extended" file format and can contain more information, such as component identification and graphic details.

RS-274-D: An older Gerber format, which needs a separate auxiliary file to describe the supplementary information in graphics, is not as commonly used as RS-274X format.

Gerber file describes the circuit pattern by containing a series of instructions. For example, an instruction may mean "draw a straight line" or "draw a circle"-these instructions together form a complete graphic of a PCB layer.

4. Generation of Gerber file

Gerber files are usually generated by electronic design automation (EDA) software, such as Altium Designer, Eagle, KiCad, etc. After designing the circuit diagram and layout, these softwares will output corresponding Gerber files according to the designed layers. During the generation process, designers need to confirm the following aspects:

Hierarchical setting: ensure that each design layer (such as signal layer, power layer, screen printing layer, etc.) is output correctly.

Precision requirements: The precision of the path (usually micron level) is defined in the Gerber file to ensure that the details of the circuit board are accurately conveyed to the manufacturer.

Drilling information: If there is a position on the PCB that needs to be drilled (such as component pin hole), it will also be described through the drilling layer in the Gerber file.

5. Application of Gerber file

Gerber file is the most basic data format in the process of PCB manufacturing and assembly, which is widely used in the following links:

PCB manufacturing: The manufacturer uses the information such as copper layer and solder mask in the Gerber file to carry out lithography and etching of PCB.

Component placement and welding: Through screen printing layer and component placement layer, the manufacturer can determine the placement position of components and the specific welding area.

Drilling: the drilling layer indicates the position where holes should be drilled on the PCB for use by the drilling machine.

6. Transmission and verification of Gerber file

Once the Gerber files are generated, they will be transmitted to the PCB factory. In order to ensure the accuracy of manufacturing, designers usually use the "Gerber Viewer" tool to check the documents and confirm whether the information of each layer meets the expectations. These tools can simulate the effect of overlapping layers and help identify potential design errors, such as routing errors and drilling position errors.

In addition, many companies will use the design document verification (DFM/DFA) tool to review the Gerber document to ensure that the document meets the requirements of the manufacturing process and optimize the manufacturing process.

7. The challenge of the Gerber document

File integrity and accuracy: Because the Gerber file contains complex graphic paths and multiple layers, minor errors in any file may lead to PCB manufacturing defects. Therefore, it is very important to ensure the accuracy and completeness of the document.

Version compatibility: There may be format differences between different versions of Gerber files, so when transmitting across different design platforms and manufacturers, it is necessary to ensure version compatibility to avoid errors due to format mismatch.

Complexity management: With the increase of design complexity (such as multi-layer PCB, 3D packaging, etc.), the complexity and management difficulty of Gerber files also increase, and designers need to manage each design layer more carefully.

summarize

Gerber file is an important file format in the process of PCB design and manufacturing, which is used to accurately describe the pattern of each PCB layer. It provides PCB manufacturers with detailed requirements of designers to ensure the smooth progress from design to production. Through the accurate generation, transmission and verification of Gerber files, design errors can be greatly reduced, and manufacturing efficiency and product quality can be improved. Gerber file is still one of the most widely used standard data formats in modern integrated circuit packaging and manufacturing.

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