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Common circuit board quality problems and improvement measures in multi-layer PCB solder mask process
In the multi-layer 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 multilayer PCB 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: use white paper to seal the net
problem: sticky film
Reason 1: The circuit board ink is not dried
Improvement measures: check the degree of ink drying
Reason 2: Multi-layer PCB vacuum is too strong
Improvement measures: check the vacuum system (the air guide strip may not be added)
Problem: Poor exposure
Reason 1: Poor vacuum
Improvement measures: check the vacuum system
Reason 2: Multi-layer PCB exposure energy is inappropriate
Improvement measures: adjust the appropriate exposure energy
Reason 3: The temperature of the multi-layer PCB exposure machine is too high
Improvement measures: check the temperature of the exposure machine (below 26)
Problem: The ink does not dry out
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: Less thinner
Improvement measures: increase thinner, 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 company 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: It takes too long after printing
Improvement measures: control the storage 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 exposure energy
Reason 5: Multi-layer 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 the printed circuit board
Reason 7: Not enough developing potion
Improvement measures: the temperature is not enough to check the concentration and temperature of the medicine
Reason 8: The thinner does not match
Improvement measures: use matching thinner [please use company 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 [Ink does not dry]
Problem: Green Oil Bridge Broken Bridge
Reason 1: Insufficient exposure energy
Improvement measures: Increase exposure energy
Reason 2: The sheet 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-treatment of multi-layer PCB boards to 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-bake
Improvement measures: Baking process after inspection
Problem: Poor upper tin
Reason 1: The development is not clean
Improvement measures: improve several factors of poor image development
Reason 2: Post-baking solvent contamination
Improvement measures: increase oven exhaust or machine cleaning before spraying tin
problem: post-baking and exploding oil
Reason 1: There is no segmented baking
Improvement measures: stage baking
Reason 2: Insufficient viscosity of multi-layer PCB plug hole ink
Improvement measures: adjust plug hole ink viscosity
Problem: Ink matte
Reason 1: The thinner does not match
Improvement measures: use matching thinner [please use company supporting thinner]
Reason 2: Low exposure energy
Improvement measures: Increase exposure energy
Reason 3: Overdeveloped circuit board
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: Multilayer circuit board substrate oxidation
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: Ink type selection is inappropriate.
Improvement measures: Change to appropriate ink.
Reason 2: The ink type selection is inappropriate.
Improvement measures: Change to appropriate ink.
Reason 3: The drying time, temperature is not correct, 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: The viscosity of the multilayer PCB ink 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 circuit board silk screen pressure is too large.
Improvement measures: reduce stress.
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.
iPCB is a high-tech manufacturing enterprise focusing on the development and production of high-precision PCBs. iPCB is happy to be your business partner. Our business goal is to become the most professional prototyping PCB manufacturer in the world. Mainly focus on microwave high frequency PCB, high frequency mixed pressure, ultra-high multi-layer IC testing, from 1+ to 6+ HDI, Anylayer HDI, IC Substrate, IC test board, rigid flexible PCB, ordinary multi-layer FR4 PCB, etc. Products are widely used in industry 4.0, communications, industrial control, digital, power, computers, automobiles, medical, aerospace, instrumentation, Internet of Things and other fields.
