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What is PCB etching?

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Published by: Keyou June 20,2019

The process from the light board to the display of the printed circuit board is a relatively complex process of physical and chemical reactions. At present, the typical process of PCB processing adopts "graphic plating method". That is, a layer of lead-tin resist is pre-plated on the copper foil portion to be retained on the outer layer of the board, that is, the pattern portion of the circuit, and then the remaining copper foil is chemically etched away, which is called PCB etching.
The PCB etching method is a method of removing the copper foil other than the conductive line by using an etching solution. The engraving method is a method of removing the copper foil other than the conductive line by an engraving machine. The former is a chemical method, which is more common, and the latter is a physical method. .
The PCB etching method is a chemical etching method, which is a circuit board made by etching copper which is not required by concentrated sulfuric acid. The engraving method uses a physical method, a special engraving machine, and a method of engraving a copper plate to form a circuit trace.
Learn about the issues you should be aware of during the PCB etching process.

 

                                PCB etching 

 

Factors affecting side erosion


1. PCB etching method: Soaking and bubbling etching will cause large side etching, and the side etching of splashing and spray etching is small, especially the spray etching effect is the best.


2, the type of PCB etching solution: different etching liquid chemical composition is different, the etching rate is different, and the etching coefficient is also different. For example, an acid chloride copper etching solution usually has an etching coefficient of 3, and an alkaline copper chloride etching solution has an etching coefficient of 4. Recent studies have shown that a nitric acid-based etching system can achieve almost no side etching, and the sidewalls of the etched lines are nearly vertical. This etching system is yet to be developed.

 

                                 PCB etching


3, PCB etching rate: slow etching rate will cause severe side etching. The improvement in etching quality is greatly related to the acceleration of the etching rate. The faster the etching speed, the shorter the time the board stays in the etching solution, and the smaller the amount of side etching, the clear and tidy pattern.

4. PH value of PCB etching solution: When the pH value of alkaline etching solution is high, the side etching increases. In order to reduce the side erosion, the general pH should be controlled below 8.5.


5, the density of PCB etching solution: the density of the alkaline etching solution is too low will increase the side etching, the use of high copper concentration of etching solution is beneficial to reduce side etching.

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