PCB News - PCB solder mask process

PCB solder mask process

Solder mask is a layer of ink printed on the surface of the PCB. It not only plays a role in insulation, but also plays a role in protecting the copper surface. It also plays a beautiful role. It is like a piece of clothing worn on the outside of the PCB proofing. It is easy to find any flaws, so solder mask is also the most prone to customer complaints among all processes. In the PCB solder mask process, you may also encounter various quality problems if you are smart and experienced. The following Shenzhen circuit board manufacturers summarize some common problems for you, and hope to inspire and help you. The common ones are as follows:

Problem: penetration, blur
Reason 1: The ink viscosity is too low.
Improvement measures: increase the concentration without adding diluent.
Reason 2: The screen printing pressure is too high.
Improvement measures: reduce pressure.
Reason 3: Bad squeegee.
Improvement measures: Replace or change the angle of the squeegee screen.
Reason 4: The distance between the screen and the printing surface is too large or too small.
Improvement measures: adjust the spacing.
Reason 5: The tension of the silk screen becomes smaller.
Improvement measures: re-make a new screen version.

Problem: sticky film
Reason 1: The ink is not baked dry
Improvement measures: check the ink dryness
Reason 2: The vacuum is too strong
Improvement measures: check the vacuum system (can not add air guide)

Problem: Poor exposure
Reason 1: Poor vacuum
Improvement measures: check the vacuum system
Reason 2: Improper exposure energy
Improvement measures: adjust the appropriate exposure energy
Reason 3: The temperature of the exposure machine is too high
Improvement measures: check the temperature of the exposure machine (below 26°C)

Problem: White spots in printing
Reason 1: White spots in printing
Improvement measures: mismatched diluents, use matching diluents [please use the company's supporting diluents]
Reason 2: The sealing tape is dissolved
Improvement measures: switch to white paper to seal the net

Problem: Excessive development (corrosion test)
Reason 1: The concentration of the potion is too high and the temperature is too high
Improvement measures: reduce the concentration and temperature of the potion
Reason 2: Development time is too long
Improvement measures: shorten the development time
Reason 3: insufficient exposure energy
Improvement measures: increase exposure energy
Reason 4: The developing water pressure is too large
Improvement measures: lower the developing water pressure
Reason 5: Ink mixing is uneven
Improvement measures: stir the ink evenly before printing
Reason 6: The ink is not dried
Improvement measures: Adjust the baking parameters, see the question [The ink does not dry]

Problem: the ink won't dry
Reason 1: The oven exhaust is not good
Improvement measures: check the exhaust air condition of the oven
Reason 2: The oven temperature is not enough
Improvement measures: Determine whether the actual temperature of the oven reaches the required temperature of the product
Reason 3: Put less thinner
Improvement measures: increase diluent, fully dilute
Reason 4: The thinner dries too slowly
Improvement measures: use matching thinner [please use the company's supporting thinner]
Reason 5: The ink is too thick
Improvement measures: appropriately adjust the ink thickness

Problem: Green Oil Bridge Broken Bridge
Reason 1: Insufficient exposure energy
Improvement measures: increase exposure energy
Reason 2: The board is not handled properly
Improvement measures: check the treatment process
Reason 3: Too much pressure for developing and washing
Improvement measures: check the developing and washing pressure

Problem: post-bake oil
Reason 1: There is no segmented baking
Improvement measures: segmented baking
Reason 2: Insufficient viscosity of plug hole ink
Improvement measures: adjust the ink viscosity of the plug hole

Problem: Poor upper tin
Reason 1: The development is not clean
Improvement measures: improve several factors of poor development
Reason 2: Post-baking solvent contamination
Improvement measures: increase oven exhaust or machine cleaning before spraying tin

Problem: Foaming on the tin
Reason 1: Excessive development
Improvement measures: improve the development parameters, see the problem [over development]
Reason 2: The pre-treatment of the board is not good, and the surface is oily and dusty
Improvement measures: do a good job of pre-treatment of the board and keep the surface clean
Reason 3: insufficient exposure energy
Improvement measures: check the exposure energy and meet the ink usage requirements
Reason 4: Abnormal flux
Improvement measures: adjust flux
Reason 5: Insufficient post-baking
Improvement measures: baking process after inspection

Problem: Ink discoloration
Reason 1: Insufficient ink thickness
Improvement measures: increase ink thickness
Reason 2: Oxidation of the substrate
Improvement measures: check the pre-treatment process
Reason 3: The post-baking temperature is too high
Improvement measures: too long time after checking the baking parameters

Problem: The development is not clean
Reason 1: The storage time after printing is too long
Improvement measures: control the placement time within 24 hours
Reason 2: The ink runs out before development
Improvement measures: work in the darkroom before developing (the fluorescent lamp is wrapped in yellow paper)
Reason 3: Not enough developing potion
Improvement measures: the temperature is not enough, check the concentration and temperature of the medicine
Reason 4: Development time is too short
Improvement measures: extend the development time
Reason 5: Exposure energy is too high
Improvement measures: adjust the exposure energy
Reason 6: The ink is over-baked
Improvement measures: adjust the baking parameters, not to burn to death
Reason 7: Ink mixing is uneven
Improvement measures: stir the ink evenly before printing
Reason 8: The thinner does not match
Improvement measures: use matching thinner [please use the company's supporting thinner]

Problem: ink matt
Reason 1: The thinner does not match
Improvement measures: use matching thinner [please use the company's supporting thinner]
Reason 2: Low exposure energy
Improvement measures: increase exposure energy
Reason 3: Excessive development
Improvement measures: improve the development parameters, see the problem [over development]

Problem: Blocking the Internet
Reason 1: Drying is too fast.
Improvement measures: add slow drying agent.
Reason 2: The printing speed is too slow.
Improvement measures: increase the speed and slow down the drying agent.
Reason 3: The ink viscosity is too high.
Improvement measures: add ink lubricant or extra slow drying agent.
Reason 4: The thinner is not suitable.
Improvement measures: use designated thinners.

Problem: Ink adhesion is not strong
Reason 1: The ink model is not suitable.
Improvement measures: use appropriate inks.
Reason 2: The ink model is not suitable.
Improvement measures: use appropriate inks.
Reason 3: The drying time and temperature are incorrect and the exhaust air volume during drying is too small.
Improvement measures: use the correct temperature and time, and increase the exhaust air volume.
Reason 4: The amount of additives is inappropriate or incorrect.
Improvement measures: adjust the dosage or switch to other additives.
Reason 5: The humidity is too high.
Improvement measures: improve air dryness.

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