PCB circuit boards and double-sided circuit boards and above will need to sink copper in the holes, so that the vias have copper and become electrical vias.

However, during the production process, the manufacturer will accidentally find that there is no copper in the hole or the copper is not saturated after the copper sinking. Now our company briefly describes several reasons. The reason why there is no copper in the hole is nothing more than:

1. Drilling dust plug holes or thick holes.

2. There are bubbles in the potion when sinking copper, and no copper sinks in the hole.

3. There is circuit ink in the hole, no protective layer is applied, and there is no copper in the hole after etching.

4. The acid-base potion in the hole is not cleaned after the copper is deposited or after the board is electrified, and the parking time is too long, and slow bite corrosion occurs.

5. Improper operation, the stay time is too long in the micro-etching process.

6. The pressure of the punching plate is too large, (the designed punching hole is too close to the conductive hole) and the middle is regularly broken.

7. Electroplating potions (tin, nickel) have poor penetration ability.

To improve the reasons for these 7 major problems of copper-free holes.

1. Add high-pressure water washing and de-smear processes for holes that are prone to dust (such as 0.3mm or less with a diameter of 0.3mm).

2. Improve potion activity and shock effect.

3. Change the printing screen and counterpoint film.

4. Extend the washing time and specify how many hours to complete the graphic transfer.

5. Set the timer.

6. Increase explosion-proof holes to reduce the force on the board.

7. Do regular penetration tests.