Provide documents and PCBA material list before pcb production

Most engineers are used to sending PCB files directly to PCB factories after they have been designed. However, the most popular practice in the world is to convert PCB files into GERBER files and drill data and then hand them over to PCB. Why do you want to "do more than this"?

Because PCB production engineers and PCB design engineers have different understandings of PCB, the GERBER file converted from the PCB factory may not be what you want. For example, when you define the parameters of components in the PCB file during design, you do not want these parameters to be displayed on the finished PCB. Without your explanation, the PCB factory follows the lead and leaves these parameters on the finished PCB. This is just an example. If you convert PCB files to GERBER files yourself, you can avoid such events.

pcb design

GERBER file is an international standard photo format file, which includes RS-274-D and RS-274-X formats. RS-274-D is called the basic GERBER format, and a D code file must be attached at the same time to fully describe a drawing; RS-274-X is called extended GERBER format, which contains D-code information. Common CAD software can generate these two formats.

How to check the correctness of the generated GERBER? You only need to import these GERBER files and D code files in the free software Viewmate V6.3 to see them on the screen or print them out through the printer.

Drilling data can also be generated by various CAD software, generally in Excel format, and can also be displayed in Viewmate. No PCB can be made without drilling data.

Bill of materials during PCB manufacturing in PCBA

PCBA will appear in almost every kind of electronic equipment. It is the carrier of all electronic equipment. There are PCBA everywhere in the computer. From household appliances in daily life to vehicle mounted electronic equipment, the application of PCB is indispensable. What materials are needed in PCB manufacturing? Let's get to know.

1. Substrate

The original material of printed circuit board is copper clad substrate, referred to as substrate. The base plate is a resin plate with copper on both sides. The most commonly used sheet code is FR-4. FR-4 is mainly used for computer, communication equipment and other electronic products. Requirements for plates: first, flame resistance, second, Tg point, and third, dielectric constant. The circuit board must be flame resistant, cannot burn at a certain temperature, and can only be softened.

2. Copper foil

Copper foil is a conductor that forms wires on the substrate. There are two methods for manufacturing copper foil: calendering and electrolysis.

3、PP

PP is an indispensable raw material in the production of circuit boards, and its role is the adhesive between layers. In short, the substrate sheet in the b-stage is called PP. The specification of PP is the thickness and glue (resin) content.

4. Dry film

Photosensitive dry film is called dry film for short. Its main component is a kind of resin which is sensitive to specific spectrum and generates photochemical reaction. The practical dry film has three layers, and the photosensitive layer is sandwiched between the upper and lower layers of plastic film for protection. According to the chemical characteristics of photosensitive substances, there are two types of dry films, photopolymerization and photodegradation. Photopolymerized dry film will harden under the light of specific spectrum, and change from water-soluble material to water-insoluble, while the photodegradation is just the opposite.

5. Anti soldering paint

Solder proof paint is actually a kind of solder resist, which is a kind of liquid photosensitive material that has no affinity for liquid solder. Like the photosensitive dry film, it will change and harden under the light irradiation of specific spectrum. When used, the anti welding paint shall be mixed with the hardener. Solder proof paint is also called ink. The color of PCB we usually see is actually the color of solder mask.

6. Negative film

The negative we are talking about is similar to the photographic negative, which is a material that uses light-sensitive materials to record images. The customer transmits the designed circuit diagram to the Circuit board factory, and the workstation of the CAM center outputs the circuit diagram, but not through a common printer, but through a photo plotter. The role of the negative in the PCB factory is very important. All things on the substrate must be turned into the negative first by using the image transfer principle.