Handling of Common Problems in Solder Mask Ink Screen Printing

Solder resist ink printing in the PCB process is to apply the solder resist ink to the printed circuit board by screen printing. This article lists some common faults and solutions in the use of solder mask inks.

Ink Adhesion is Not Strong
Cause 1:
Ink model selection is not appropriate.
Solution:
Change to the appropriate ink.

Cause 2:
The surface of the print is untreated or incompletely treated.
Solution:
Add silk screen pre-treatment process and perfect pre-treatment process.

Cause 3:
Incorrect drying time, temperature and too little exhaust air during drying.
Solution:
Use the correct temperature and time, and increase the exhaust air volume.

Cause 4:
Inappropriate or incorrect amounts of additives are used.
Solution:
Adjust the dosage or use other additives.

Cause 5:
Humidity is too high.
Solution:
Improve air dryness.

Clogged Mesh
Cause 1:
Drying too fast.
Solution:
Add slow drying agent.

Cause 2:
Printing speed is too slow.
Solution:
Increase the speed and slow down the drying agent.

Cause 3:
Ink viscosity is too high.
Solution:
Add ink lubricant or extra slow drying agent.

Cause 4:
Thinners are not suitable.
Solution:
Use the specified thinner.

Bleeding Hazing
Cause 1:
Ink viscosity too low.
Solution:
Increase the concentration without adding diluent.

Cause 2:
Screen printing pressure is too high.
Solution:
Reduce the pressure.

Cause 3:
Bad squeegee.
Solution:
Change or change the angle of the squeegee screen.

Cause 4:
The distance between the stencil and the printing surface is too large or too small.
Solution:
Adjust spacing.

Cause 5:
The tension of the silk screen becomes smaller.
Solution:
Make a new screen version.

Ink wrinkle
Cause 1:
Ink is too thick.
Solution:
Reduce viscosity.

Cause 2:
The ink dries too slowly.
Solution:
Speed ​​up drying agent.

Cause 3:
Insufficient drying.
Solution:
Increase drying temperature or extend time.

Cause 4:
The storage environment after screen printing is not good.
Solution:
Reduce temperature and humidity and increase ventilation.

Blisters and Pinholes
Cause 1:
Ink viscosity is too high.
Solution:
Reduce viscosity.

Cause 2:
The screen is too fast from the board during screen printing.
Solution:
Decrease off-board speed.

Cause 3:
The countertop is uneven.
Solution:
Adjust or replace the countertop.

Cause 4:
The ink itself is the problem.
Solution:
Add defoamer or replace ink.

Cause 5:
The ink did not sit for a while after stirring.
Solution:
After the ink is stirred, it needs to be used for a period of time.

Cause 6:
Bake the board directly after screen printing.
Solution:
After screen printing, it needs to stand for a period of time before drying the board.

The Ink turns white after curing
Cause 1:
Diluent mismatch.
Solution:
Use the specified thinner instead.

Cause 2:
Ink contains moisture.
Solution:
Replace with new ink.

Cause 3:
Air humidity is high.
Solution:
Reduce air humidity.