How to Solve the Defects of PCB Hole Metallization Technology

In PCB factories, hole metalization usually consists of 8~9 steps of chemical working fluid treatment to complete the entire process. For each technology condition control of each step, some quality defects may occur, thus affecting the quality of the final electroless copper. Do you know what causes the defect? And how to solve these defects?

 

 

 

1. The backlight is unstable and there is no copper in the hole wall

Reason:

1) The working fluid components of electroless copper plating are out of balance or the technology conditions are out of control.

2) The regulator is missing or invalid.

3) The activator component is low or the temperature is low.

4) Acceleration is too strong.

5) The base material are different and the drilling stain removal is too strong.

6) The inner layer of the hole wall is broken or peeled off during drilling.

 

 

Solution:

1) Adjust the working fluid components and technology conditions, especially increase the HCHO content, increase the temperature appropriately or reduce the addition of stabilizer-containing components to improve the activity of the working fluid.

2) Add or replace the regulator at normal temperature.

3) Add activator and increase the temperature.

4) Reduce the accelerator concentration or board immersion time.

5) Appropriately reduce the intensity of drilling stain removal, and increase the activity of the activator and electroless copper plating solution.

6) Improve the quality of drill bits, base materials, and black oxide removal treatments.

 

 

2. There is no copper on the hole wall after electroplating

Reason:

1) Chemical copper is too thin and oxidized.

2) The micro-etching treatment before electroplating is too strong.

3) There are bubbles in the plating holes.

 

 

Solution:

1) Increase the thickness of chemical copper.

2) Adjust micro-etching intensity.

3) Add a plating vibrator.

 

 

3. The hole becomes thicker

Reason:

1) The electroless copper plating working fluid is unstable and copper powder precipitates.

2) The activator working fluid is not filtered.

3) Insufficient water washing after activator.

4) The accelerating working fluid is out of balance or fails.

 

 

Solution:

1) Filter the working fluid, adjust the components of the working fluid, and adjust the temperature.

2) Filter the activator working fluid.

3) Increase the amount of water washed.

4) Adjust or replace the working fluid.

 

 

4. Hole wall bursting

Reason:

1) The thickness of the plating layer is not enough.

2) The electroless copper plating is uneven and has holes. The unevenness after electroplating causes hole wall stress.

3) It cannot be washed clean after using the regulator.

4) The drilling contamination was not removed enough, and there was resin residue on the hole wall.

 

 

Solution:

1) Increase the coating thickness to 25μm.

2) Improve the deposition of electroless copper plating.

3) Strengthen the water washing of the regulator.

4) Strengthen the ability to remove drilling contamination.

 

 

5. Hole wall is irregular

Reason:

1) The drill bit for drilling is old.

2) The removal of drilling contamination is too strong, causing the resin to be etched too deeply and exposing the fibers.

 

 

Solution:

1) Replace the drill bit with a new one.

2) Adjust the swelling agent and potassium permanganate technology conditions for removing drilling contamination to reduce the ability to remove drilling contamination.

 

 

6. The small hole is blocked

Reason:

1) When drilling, the resin residue is not completely removed.

2) There is a lot of sediment in each medicine tank and water tank.

3) The reducing agent in the drilling contamination removal process is too strong.

 

 

Solution:

1) Improve drilling, especially drill bits.

2) Filter working fluids, especially potassium permanganate, palladium liquid, electroless copper plating and other working fluids. Clean the water washing tank and increase the washing water flow.

3) Adjust the reducing power of the reducing agent.

 

 

HoYoGo is an international, professional and reliable PCB factory. We have experience in the production of single-sided and double-sided and multilayer PCB, and have high level automation and dedicated automotive production lines. We can also provide you with preferential prices to meet your customization needs. If you have related needs, you are welcome to send us your inquiry.