Common circuit board quality problems and improvement measures in PCB solder mask process

　　In the PCB solder mask process, as smart as you may encounter various problems in the production of circuit boards, the common ones are as follows:

　　Problem: White spots in printing

　　Reason 1: The printed PCB board has white spots

　　Improvement measures: the thinner does not match, use the matched thinner [please use the company's supporting thinner]

　　Reason 2: The circuit board is dissolved in the sealing tape

　　Improvement measures: switch to white paper to seal the net

　　Problem: sticky film

　　Reason 1: The circuit board ink is not dried

　　Improvement measures: check the ink dryness

　　Reason 2: PCB 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: PCB exposure energy is inappropriate

　　Improvement measures: adjust the appropriate exposure energy

　　Reason 3: PCB exposure machine temperature is too high

　　Improvement measures: check the temperature of the exposure machine (below 26°C)

　　Problem: the ink won't dry

　　pcb circuit board/circuit board screen printing room

　　pcb circuit board/circuit board screen printing room

　　Reason 1: The exhaust air of the circuit board oven is not good

　　Improvement measures: check the exhaust air condition of the oven

　　Reason 2: Reduce the amount of thinner

　　Improvement measures: increase diluent, fully dilute

　　Reason 3: The ink is too thick

　　Improvement measures: appropriately adjust the ink thickness

　　Reason 4: The thinner dries too slowly

　　Improvement measures: use matching thinner [please use the company's supporting thinner]

　　Reason 5: The oven temperature is not enough

　　Improvement measures: Determine whether the actual temperature of the oven reaches the required temperature of the product

　　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: Development time is too short

　　Improvement measures: extend the development time

　　Reason 4: Exposure energy is too high

　　Improvement measures: adjust the exposure energy

　　Reason 5: The circuit board ink is over-baked

　　Improvement measures: adjust the baking parameters, not to burn to death

　　Reason 6: Ink mixing is uneven

　　Improvement measures: stir the ink evenly before printing

　　Reason 7: Not enough developing potion

　　Improvement measures: check the concentration and temperature of the potion if the temperature is not enough

　　Reason 8: The thinner does not match

　　Improvement measures: use matching thinner [please use the company's supporting thinner]

　　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: 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: Foaming on the tin

　　Circuit board solder mask text screen printing room

　　Circuit board solder mask text screen printing room

　　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-processing the PCB 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: 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: post-bake oil

　　Reason 1: There is no segmented baking

　　Improvement measures: segmented baking

　　Reason 2: PCB plug hole ink viscosity is not enough

　　Improvement measures: adjust the ink viscosity of the plug hole

　　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: The circuit board is overdeveloped

　　Improvement measures: improve the development parameters, see the problem [over development]

　　Problem: Ink discoloration

　　Reason 1: Insufficient ink thickness

　　Improvement measures: increase ink thickness

　　Reason 2: Oxidation of circuit board substrate

　　Improvement measures: check the pre-treatment process

　　Reason 3: The post-baking temperature is too high

　　Improvement measures: the time is too long to check the baking parameters

　　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.

　　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: PCB 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: penetration, blur

　　Reason 1: The ink viscosity is too low.

　　Improvement measures: increase the concentration without adding diluent.

　　Reason 2: The printing pressure of the circuit board is too large.

　　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.

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