PCB Technical - PCB cross file type and ceramic PCB are expensive

Types of documents that PCB handed over to the manufacturer

The best is the GERBER file, but also the PCB source file.

Most PCB design engineers are accustomed to designing the PCB files and sending them directly to the PCB factory for processing. However, the most popular method in the world is to convert the PCB files into GERBER files and drilling data and then submit them to the PCB factory. ?

Because PCB production engineers and PCB design engineers have different understanding of PCB, the GERBER file converted by the PCB factory may not be what you want. For example, when you design the parameters of the components in the PCB file, you don’t want these The parameters are displayed on the finished PCB. You haven't explained them. The PCB factory keeps these parameters on the finished PCB. This is just an example. If you convert the PCB file into a GERBER file, you can avoid such incidents.

The GERBER file is an international standard gerber file format. It contains two formats: RS-274-D and RS-274-X. RS-274-D is called the basic GERBER format, and it must be accompanied by a D code file. Describe a picture completely; RS-274-X is called the extended GERBER format, which itself contains D code information. Commonly used CAD software can generate these two format files.

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

Drilling data can also be generated by various CAD software, the general format is Excellon, which can also be displayed in Viewmate. Of course, PCB can't be made without drilling data.

The reason why ceramic PCB is more expensive than resin PCB and metal PCB

In the PCB industry, resin PCBs, metal PCBs, and ceramic PCBs. Among them, resin is the cheapest and ceramic is the most expensive. So where is ceramics expensive?

1. Substrate material

Ceramic PCBs are currently mainly divided into two types: alumina and aluminum nitride, both of which cost more than resin substrates, aluminum substrates and copper substrates.

2. Manufacturing process

The preparation methods of ceramic substrates can be divided into four categories: HTCC, LTCC, DBC and DPC. These four process requirements and undertakings are relatively high

HTCC requires a high temperature above 1300°C, and the cost of electrode selection is relatively high.

LTCC requires a calcination process at 850°C, and the accuracy is poor, so the yield is low.

DBC requires the formation of alloys between copper foil and ceramics, and the calcination temperature needs to be strictly controlled within the temperature range of 1065-1085°C, and the thickness of the copper foil should generally not be less than 150-300 microns.

DPC includes vacuum coating, wet coating, exposure and development, etching and other process links. The shape processing requires laser cutting.

3. Product performance

Ceramic PCB has properties that organic substrates do not possess, such as high thermal conductivity, excellent chemical stability and thermal stability.

Higher thermal conductivity;

More matching coefficient of thermal expansion;

Stronger, lower resistance metal film;

The substrate has good reliability and high temperature resistance;

Good insulation;

Low high frequency loss;

Can be assembled in high density;

No organic ingredients, high reliability in aerospace and long life;

The copper layer does not contain an oxide layer and can be used for a long time in reducing gases.