PCB Tech - Circuit board factory: improve the method of short circuit caused by etching

Circuit board factory: improve the method of short circuit caused by etching

Short circuits cause considerable harm to circuit board factories. Unclean etching is an important cause of circuit board short circuits. Finding ways to improve the etching process to reduce short circuits is a process that circuit board factories must go through, especially in the printed circuit board manufacturing process. In the process, the requirements of the etching process have become more and more refined.

The short-circuit causes considerable harm to the circuit board factory, ranging from burning components to large PCB circuit boards being scrapped. We can only try to avoid short circuits, we must grasp every step of the production, and do not miss every suspicious point during inspection. In the etching process, the aspects that usually cause the circuit board to short-circuit include: improper control of the etching solution parameters, and uneven thickness of the electroplated layer when the entire board is electroplated with copper, resulting in unclean etching. The quality of the etching yao water parameter control directly affects the quality of the circuit board to the etching. The following is the specific analysis of the etching solution of the Shenzhen circuit board factory:

1. PH value: controlled between 8.3 and 8.8. If the PH value is low, the solution will become viscous, the color will be white, and the corrosion rate will decrease. This situation is likely to cause side corrosion, which is mainly controlled by adding ammonia PH value.

2. Chloride ion: control between 190~210g/L, mainly through the etching salt to control the chloride ion content, the etching salt is composed of ammonium chloride and supplements.

3. Specific gravity: The specific gravity is mainly controlled by controlling the content of copper ions. Generally, the content of copper ions is controlled between 145 and 155g/L, and the test is performed every one hour or so to ensure the stability of the specific gravity.

4. Temperature: Control at 48~52 degree Celsius. If the temperature is high, the ammonia volatilizes quickly, it will cause the pH value to be unstable, and most of the cylinder of the etching machine is made of PVC material, and the PVC temperature resistance limit is 55 degree Celsius, Exceeding this temperature will easily cause the cylinder body to deform and even cause the etching machine to be scrapped. Therefore, an automatic thermostat must be installed to effectively monitor the temperature to ensure that it is within the control range.

5. Speed: Generally adjust the appropriate speed according to the thickness of the bottom copper of the plate.

In order to achieve the stability and balance of the above parameters, it is recommended to configure an automatic feeder to control the chemical components of the sub-liquid and make the composition of the etching liquid in a relatively stable state.

The thickness of the electroplating layer is uneven when the copper is electroplated on the whole board, which leads to the improvement method of unclean etching.

1. When electroplating the whole circuit board, try to realize automatic line production. At the same time, adjust the current density per unit area (1.5~2.0A/dm2) according to the size of the hole area, and keep the plating time as consistent as possible. Increase the cathode and anode baffles, and formulate the use system of "plating edge strips" to reduce the potential difference.

2. If the full-board electroplating of the circuit board is manual line production, the large board needs to be electroplated with double clamps, try to keep the current density per unit area consistent, and install a timing alarm to ensure the consistency of the plating time and reduce the potential difference.