Question

What are the causes of copper-free holes?

Answer 1

The reasons for no copper holes are:

1. Insufficient or excessive desmear removal (causing resin changes and poor washing).

2. Plug the holes with drilling dust or make the holes thicker.

3. Cracks in the hole wall or splitting between the inner layers after drilling.

4. Insufficient neutralization treatment after removing the slag, resulting in residual alkali stannate compounds in the holes.

5. The imbalance of cleaning and degreasing liquid concentration and other ratios affects the adsorption of Pd.

6. The concentration of the activation solution is low, which affects the adsorption of Pd.

7. The processing is over-accelerated, and Pd is also removed when Sn is removed.

8. Chemical copper potion potion has poor activity.

9. There are bubbles in the holes, circuit ink in the holes, no protective layer, and no copper in the holes after etching.

Answer 2

The reasons for no copper holes are generally as follows:
1. Drill the dust plug hole or hole thickness
2. There are bubbles in the liquid when depositing copper, but no copper is deposited in the holes.
3. There is circuit ink in the hole, no protective layer is applied, and there is no copper in the etched post-hole.
4. After the copper is deposited or the plate is charged, the acid and alkali solution in the hole is not cleaned, and the hole is left for too long, resulting in slow corrosion.
5. Improper operation, staying too long during the micro-etching process
6. The stamping pressure is too high and the middle (the designed punching hole and the conductive hole are too close to each other) are neatly disconnected.
7. Poor penetration ability of electroplating liquid (tin and nickel)

Improvements were made in view of these seven problems with no copper air holes:
1. For holes that are prone to dust (for example, hole diameters below 0.3 mm include 0.3 mm), add high-pressure water washing and slag removal procedures
2. Improve the activity and vibration effect of the medicinal solution
3. Replace the printing screen and registration film
4. Extend the washing time and specify how many hours to complete the graphic transfer.
5. Set a timer
6. Add explosion-proof holes to reduce stress on the board
7. Conduct penetration tests regularly