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

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 not suitable

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

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

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.