Common quality problems and improvement measures in PCB solder mask process

Question: Printing has white spots

Reason 1: Printing has white spots

Improvement measures: The diluent does not match the matching diluent [Please use the company's matching thinner]

Reason 2: The sealing tape is dissolved

Improvement measures: use white paper to seal the net

Question: Sticky film

Reason 1: The ink is not baked dry

Improvement measures: check the degree of ink drying

Reason 2: The vacuum is too strong

Improvement measures: check the vacuum system (without gas guides)

Problem: Poor exposure

Reason 1: Poor vacuum

Improvement measures: check the vacuum system

Reason 2: The exposure energy is not suitable

Improvement measures: adjust the appropriate exposure energy

Cause 3: The exposure machine temperature is too high

Improvements: Check the exposure machine temperature (less than 26 ° C)

Problem: Ink does not dry

Reason 1: The oven is not well exhausted

Improvement measures: check the 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: Less diluent

Improvement measures: increase the diluent and fully dilute

Reason 4: The diluent is too slow to dry

Improvement measures: use matching diluent [please use company matching thinner]

Reason 5: The ink is too thick

Improvement measures: adjust the ink thickness appropriately

Problem: development is not clean

Reason 1: The placement time after printing is too long

Improvement measures: control the placement time within 24 hours

Cause 2: The ink is removed before development

Improvement measures: work in the darkroom before development (the fluorescent lamp is wrapped in yellow paper)

Reason 3: Developing drug is not enough

Improvement measures: insufficient temperature to check the concentration of the drug, temperature

Reason 4: The development time is too short

Improvement measures: extend development time

Reason 5: Exposure energy is too high

Improvement measures: adjust the exposure energy

Reason 6: Excessive ink baking

Improvement measures: adjust the baking parameters, can not be baked

Reason 7: Uneven ink mixing

Improvement measures: Stir the ink evenly before printing

Reason 8: The diluent does not match

Improvement measures: use matching diluent [please use company matching thinner]

Problem: Overexposure (etching)

Reason 1: The concentration of the syrup is too high and the temperature is too high

Improvement measures: reduce the concentration of the syrup and the temperature of the syrup

Cause 2: The development time is too long

Improvement measures: shorten development time

Reason 3: Insufficient exposure energy

Improvement measures: increase exposure energy

Reason 4: The developing water pressure is too large

Improvement measures: reduce the development water pressure

Cause 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 [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 processed well.

Improvement measures: inspection process

Reason 3: Development and washing pressure are too high

Improvement measures: check development and washing pressure

Problem: Sparkling on tin

Reason 1: Overexposure

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

Reason 2: The pre-treatment of the board is not good, the surface is oily. Dust

Improvement measures: pre-treatment of the board to keep the surface clean

Reason 3: Insufficient exposure energy

Improvement measures: check the exposure energy to meet the ink requirements

Cause 4: Flux abnormality

Improvement measures: adjust the flux

Reason 5: Insufficient post-baking

Improvement measures: inspection and post-baking process

Problem: bad tin

Reason 1: The development is not clean

Improvement measures: to improve the development of several factors

Reason 2: Post-baking solvent contamination

Improvement measures: increase the oven exhaust or spray the machine before the machine cleaning

Problem: post-baking oil

Reason 1: No segment baking

Improvement measures: segmented baking

Reason 2: The plug hole ink viscosity is not enough

Improvement measures: Adjust the viscosity of the plug hole ink

Problem: Ink matte

Reason 1: The diluent does not match

Improvement measures: use matching diluent [please use company matching thinner]

Reason 2: Low exposure energy

Improvement measures: increase exposure energy

Reason 3: Overexposure

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

Problem: ink discoloration

Reason 1: The ink thickness is not enough

Improvement measures: increase ink thickness

Reason 2: Substrate oxidation

Improvement measures: inspection pre-treatment process

Reason 3: The post-baking temperature is too high

Improvement measures: time is too long, check the post-baking parameters

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Problem: ink adhesion is not strong

Cause 1: The ink model selection is not suitable.

Improvements: Switch to the appropriate ink.

Cause 2: The ink model selection is not suitable.

Improvements: Switch to the appropriate ink.

Cause 3: The drying time, temperature is incorrect, and the amount of exhaust air during drying is too small.

Improvement measures: use the correct temperature and time, increase the amount of exhaust air.

Reason 4: The amount of additive is not appropriate or correct.

Improvements: Adjust the dosage or switch to other additives.

Cause 5: The humidity is too large.

Improvement measures: Improve air dryness.

Problem: blocking the net

Cause 1: Drying too fast.

Improvement measures: Add slow drying agent.

Cause 2: The printing speed is too slow.

Improvement measures: increase the speed and slow down the dry agent.

Cause 3: The viscosity of the ink is too high.

Improvement measures: Add ink lubricant or extra slow drying agent.

Reason 4: The diluent is not suitable.

Improvements: Use the specified diluent.

Problem: penetration, blurring

Cause 1: The viscosity of the ink is too low.

Improvement measures: increase the concentration without adding thinner.

Cause 2: The screen printing pressure is too large.

Improvement measures: reduce stress.

Cause 3: Poor squeegee.

Improvements: Replace or change the angle of the squeegee screen.

Cause 4: The distance between the stencil and the printed surface is too large or too small.

Improvement measures: adjust the spacing.

Cause 5: The tension of the screen printing net becomes small.

Improvements: Re-create a new screen.

MTB-DC

Mietubl Global Supply Chain (Guangzhou) Co., Ltd. , https://www.mietublmachine.com