7 must-know PCB design tips for engineers

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7 must-know PCB design tips for engineers [Copy link]

1. What is the relationship between the line width and via size on the PCB board and the current passing through it?

The copper foil thickness of a general PCB is 1 ounce, about 1.4 mil, and the maximum current allowed for a line width of approximately 1 mm is 1 A. Vias are relatively complex, and in addition to being related to the size of the via pad, they are also related to the thickness of the copper deposited on the hole wall after electroplating during the processing process.

2. Why do we need to convert PCB files into GERBER files and drilling data before handing them over to the PCB factory for board making?

Most engineers are accustomed to sending the PCB files directly to the PCB factory for processing after designing them. However, the more popular practice internationally is to convert the PCB files into GERBER files and drilling data before handing them over to the PCB factory. Why do we need to do this?

Because electronic engineers and PCB engineers have different understandings of PCB, the GERBER files converted by the PCB factory may not be what you want. For example, when you define the parameters of the components in the PCB file during design, and you do not want these parameters to be displayed on the finished PCB, and you do not explain, the PCB factory will follow suit and leave these parameters on the finished PCB.

This is just an example. You can avoid this kind of thing if you convert the PCB files to GERBER files yourself.

GERBER file is an international standard photolithography format file, which includes 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 to fully describe a graphic; RS-274-X is called the extended GERBER format, which contains D code information. Commonly used 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 into 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 Excellon format, and can also be displayed in Viewmate. Of course, PCB cannot be made without drilling data.

3. How to improve the delivery rate?

To complete the design of a printed circuit board, you usually have to go through the process of inputting the schematic, generating the network table, defining the KeepoutLayer network table (components), loading the component layout, and automatically (manually) routing.

Several popular software on the market today are not very powerful in the automatic layout of components. Often, manual layout can improve the routing rate. But please don’t forget to make full use of the Move to Grid function, which can automatically move components to the intersection of the grid, which is very helpful in improving the routing rate.

4. How to add Chinese characters to PCB files ?

There are many ways to add Chinese characters to PCB files. My favorite method is the one that will be introduced below:

A. Prerequisite: Protel99 software should be installed on your PC and can run normally.

B. Steps: copy the client99.rcs English menu file in the windows directory to another directory and save it; download Protel99cn.zip, unpack it and copy the client99.rcs in it to the windows directory; then copy other files to the DesignExplorer99 directory; restart the computer and run Protel99 to display the Chinese menu, and you can add Chinese characters in the Place | Chinese Characters menu.

5. If there are only four DDR memories on the motherboard and the clock is required to reach 150Mhz , what are the specific requirements for wiring ?

150Mhz clock routing requires to minimize the length of the transmission line and reduce the impact of the transmission line on the signal. If the requirements are still not met, simulate to see if the matching, topology, impedance control and other strategies are effective.

6. After automatic copper floating, the floating copper will fill the blank space according to the position of the components on the board and the routing layout.

However, this will form many sharp corners and burrs less than or equal to 90 degrees, which will cause discharge during high-voltage testing and fail the high-voltage test. I wonder if there is any other good way except automatically floating copper and then manually correcting it bit by bit to remove these sharp corners and burrs.

The problem of sharp-corner copper floating in automatic copper floating is indeed a very troublesome problem. In addition to the discharge problem you mentioned, the acid droplet accumulation problem during processing will also cause processing problems. The above content comes from Rongronghao.

led2015

In fact, there are many omissions, and there are many details to pay attention to, such as stacking, routing, etc.

jyb271126848

Thanks for sharing. I have been looking for similar experiences to share. Today I really gained a lot. Thanks again.