One of the more common occurrences of PCB ink in actual production is the drop of the solder mask ink on the circuit board. Then what is the cause of the ink on the circuit board? How to avoid PCB solder resist ink deinking

There are many reasons for the peeling of the solder mask ink on the circuit board. Generally speaking, there are mainly the following three reasons. Here is an analysis of the three reasons for everyone, and how to solve the problem of avoiding solder mask falling off.

1. When the PCB circuit board is printed with solder resist ink, the pre-treatment is not in place. For example: There are stains, dust on the surface of the PCB board, or some areas are oxidized.

Solving this problem is the easiest. You only need to re-do the pre-treatment and do it again. Try to clean up the stains, impurities or oxide layer on the surface of the PCB circuit board to ensure that the circuit board is printed on the solder resist ink. The top is clean.

2. It is also possible that the solder mask falls off because of the oven, the baking time of the circuit board is short or the baking temperature is not enough. Because the circuit board must be baked at a high temperature after printing the thermosetting solder mask or photosensitive solder mask, and if the baking temperature or time is insufficient, the strength of the board surface ink will be insufficient, so the printed circuit board After the subsequent processing is delivered to the customer, the customer receives the board and then performs the patch processing. The high temperature of the tin furnace during the patch processing will cause the circuit board solder mask to fall off.

To solve this problem, we must first make sure that the baking display temperature of the oven is consistent with the actual baking temperature, so as to avoid the baking conditions required by the ink due to the oven temperature. Each solder mask ink has different requirements for baking time and temperature, so try to bake in accordance with the parameter conditions given by the ink manufacturer.

3. Ink quality problems or ink expired, the ink products produced by each PCB ink manufacturer will be different in quality. Sometimes, in order to control costs, circuit board manufacturers need to use cheaper circuit board solder resist inks because of For circuit board manufacturers, although solder mask ink accounts for a very small part of the production cost, if the amount is large, there will be a lot of difference, so sometimes because of cost considerations, cheaper solder mask inks are selected. The cheap solder resist ink sometimes suffers from deinking due to problems such as adhesion. There are also some small circuit board factories, the purchased ink has not been used up for a long time, and the performance of multiple use is greatly reduced, and the ink drop is more likely to occur. Generally speaking, it is recommended to use the solder mask ink within 24 hours after opening the tank and adjusting the oil. If it exceeds 24 hours, the performance of the ink will be greatly reduced.

If the customer requirements of the circuit board factory are relatively high, try to choose a good solder mask ink. After all, the ink cost accounts for less than 3% of the total cost. If you lose a stable customer because of the ink problem, it will be more than the gain. Japan’s Sun’s solder mask and Taiwan Chuanyu’s solder mask are very good. Of course, as a pseudo-patriotic youth, it is better to buy Japanese solar solder resist ink than Taiwan Chuan Yu solder resist ink. They are almost the same. Wouldn’t it be better to just choose.

Solve these three problems. Generally, solder mask inks rarely have ink deinking. If so, try to contact the ink supplier and arrange for a technician to follow up and solve it.