LR6 battery!Causes and solutions to common problems in PCB alkaline etching

　　1. Problem: Reduced etching rate in printed circuits

　　reason:

　　Caused by improper control of process parameters

　　Solution:

　　Check and adjust process parameters such as temperature, spray pressure, solution specific gravity, pH value and ammonium chloride content according to process requirements to the process specified values.

　　2. Problem: Precipitation of etching liquid in printed circuits

　　reason:

　　(1) The ammonia content is too low

　　(2) Excessive water dilution

　　(3) The specific gravity of the solution is too large

　　Solution:

　　(1) Adjust the PH value to reach the process specified value or appropriately reduce the exhaust volume.

　　(2) When adjusting, strictly follow the process requirements or appropriately reduce the exhaust volume.

　　(3) Discharge some solutions with high specific gravity according to process requirements and add aqueous solutions of ammonium chloride and ammonia after analysis to adjust the specific gravity of the etching solution to the range allowed by the process.

　　3. Problem: The metal resist coating in the printed circuit is corroded

　　reason:

　　(1) The pH value of the etching solution is too low

　　(2) Chloride ion content is too high

　　Solution:

　　(1) Adjust to the appropriate pH value according to process regulations.

　　(2) Adjust the chloride ion concentration to the process specified value.

　　4. Problem: The copper surface in the printed circuit turns black and cannot be etched.

　　reason:

　　The sodium chloride content in the etching solution is too low

　　Solution:

　　Adjust sodium chloride to the specified value according to process requirements.

　　5. Problem: There is residual copper on the surface of the substrate in the printed circuit

　　reason:

　　(1) The etching time is not enough

　　(2) The film removal is not clean or there is corrosion-resistant metal

　　Solution:

　　(1) Conduct the first piece test according to the process requirements to determine the etching time (i.e. adjust the transmission speed).

　　(2) Before etching, the board surface should be inspected according to process requirements. It is required that there is no residual film and no anti-corrosion metal plating.

　　6. Problem: The etching effect on both sides of the substrate in printed circuits is obviously different.

　　reason:

　　(1) The nozzle of the etching section of the equipment is blocked

　　(2) The conveying rollers in the equipment need to be arranged staggered before and after each rod, otherwise it will cause marks on the board surface.

　　(3) Water leakage from the nozzle causes a drop in spray pressure (often occurs at the joints between the nozzle and the manifold)

　　(4) There is insufficient solution in the liquid preparation tank, causing the motor to idle

　　Solution:

　　(1) Check the nozzle blockage and clean it in a targeted manner.

　　(2) Thoroughly recheck and arrange the staggered positions of the rollers in each section of the equipment.

　　(3) Check each joint of the pipeline and perform repairs and maintenance.

　　(4) Observe frequently and make timely additions to the positions specified by the process.

　　7. Problem: Uneven etching on the printed circuit board surface leaves some residual copper.

　　reason:

　　(1) The film removal on the surface of the substrate is not complete, and there is residual film

　　(2) When the whole board is plated with copper, the thickness of the copper layer on the board surface is uneven.

　　(3) When the board surface is corrected or repaired with ink, it gets on the driving roller of the etching machine.

　　Solution:

　　(1) The film removal on the surface of the substrate is not complete, and there is residual film.

　　(2) When the whole board is plated with copper, the thickness of the copper layer on the board surface is uneven.

　　(3) When the board surface is corrected or repaired with ink, it gets on the transmission roller of the etching machine.

　　(4) Check the film removal process conditions, adjust and improve them.

　　(5) To ensure the consistency of the thickness of the copper layer according to the density of the circuit pattern and the accuracy of the wires, the brush grinding and flattening process can be used.

　　(6) The repaired ink must be cured, and the contaminated rollers must be inspected and cleaned.

　　8. Problem: Severe side corrosion of wires was found after etching in the printed circuit board

　　reason:

　　(1) The nozzle angle is wrong and the nozzle is out of balance

　　(2) The spray pressure is too high, causing rebound and serious side erosion.

　　Solution:

　　(1) Adjust the nozzle angle and nozzle according to the instructions to meet the technical requirements.

　　(2) According to the process requirements, the spray pressure is usually set to 20-30PSIG, and adjusted through the process test method

　　9. Problem: The substrate moving forward on the conveyor belt in the printed circuit exhibits diagonal movement.

　　reason:

　　(1) The levelness of equipment installation is poor

　　(2) The nozzle in the etching machine will automatically swing back and forth from left to right. It is possible that some of the nozzles swing incorrectly, causing uneven spray pressure on the board surface and causing the substrate to tilt.

　　(3) Damage to the conveyor belt gear of the etching machine caused some of the transmission wheel rods to stop working

　　(4) The transmission rod in the etching machine is bent or twisted

　　(5) The water squeezing water stop roller is damaged

　　(6) The position of some baffles of the etching machine is too low, which blocks the conveyed boards.

　　(7) The upper and lower spray pressure of the etching machine is uneven. If the downward pressure is too high, the board will be lifted up.

　　Solution:

　　(1) Make adjustments according to the equipment instructions. Adjust the horizontal angle and arrangement of each roller section to meet the technical requirements.

　　(2) Check in detail whether the nozzle swings of each section are correct and make adjustments according to the equipment instructions.

　　(3) Inspections should be carried out section by section in accordance with process requirements, and damaged or damaged gears and rollers should be replaced.

　　(4) Replace the damaged transmission rod after detailed inspection.

　　(5) Damaged accessories should be replaced.

　　(6) After inspection, the angle and height of the baffle should be adjusted according to the equipment instructions.

　　(7) Adjust the spray pressure appropriately.

　　10. Problem: The copper on the board surface of the printed circuit board is not completely corroded, and residual copper remains on some edges.

　　reason:

　　(1) The dry film has not been completely removed (it may be that the two copper and tin-lead plating layers are too thick and wide to cover a small amount of dry film, making it difficult to remove the film)

　　(2) The conveyor belt speed in the etching machine is too fast

　　(3) During tin-lead plating, the plating solution penetrates into the bottom of the dry film, causing a very thin coating to contaminate the dry film, which slows down the corrosion of copper there and leaves residual copper at the edge of the wire.

　　Solution:

　　(1) Check the film withdrawal situation and strictly control the coating thickness to avoid coating extension.

　　(2) Adjust the speed of the etching machine conveyor belt according to the etching quality.

　　(3)A Check the film application procedure, select the appropriate film application temperature and pressure, and improve the adhesion between the dry film and the copper surface

　　B Check the slightly roughened state of the copper surface before applying the film.

　　11. Problem: The etching effect on both sides of the printed circuit board is not synchronized

　　reason:

　　(1) The thickness of the copper layers on both sides is inconsistent

　　(2) Uneven spray pressure up and down

　　Solution:

　　(1) A Adjust the upper and lower spray pressure according to the thickness of the coating on both sides (copper layer thickness points downward);

　　B uses single-sided etching and only activates the lower nozzle pressure.

　　(2)A Check the upper and lower spray pressure and adjust it according to the quality of the etched board;

　　B Check whether the nozzle of the etching section in the etching machine is blocked, and use a test plate to adjust the upper and lower spray pressure.

　　12. Problem: Excessive crystallization of alkaline etching solution in printed circuits

　　reason:

　　When the pH value of the alkaline etching solution is lower than 80, the solubility becomes poor, resulting in the formation of copper salt precipitation and crystallization.

　　Solution:

　　(1) Check whether the amount of sub-liquid in the spare tank for replenishment is sufficient.

　　(2) Check whether the controller, pipelines, pumps, solenoid valves, etc. for sub-liquid replenishment are blocked or abnormal. (3) Check whether excessive ventilation will cause a large amount of ammonia to escape and reduce the PH. (4) Check whether the function of the pH meter is normal.

　　13. Problem: The etching speed decreases during continuous etching in printed circuits, but the etching speed can be restored if the machine is shut down for a period of time.

　　reason:

　　The exhaust volume is too low, resulting in insufficient oxygen supplementation

　　Solution:

　　(1) Find the correct exhaust volume through process testing.

　　(2) Debugging should be carried out according to the instructions provided by the supplier to find the correct data.

　　14. Problem: Photoresist peeling off (dry film or ink)

　　reason:

　　(1) If the pH value of the etching solution is too high, the alkaline water-soluble dry film and ink will be easily damaged.

　　(2) The sub-liquid supply system is out of control

　　(3) The type of photoresist itself is incorrect and its alkali resistance is poor

　　Solution:

　　(1) Adjust according to the value determined by the process specification.

　　(2) Check the pH value of the sub-liquid, maintain appropriate ventilation, and prevent ammonia gas from directly entering the area where the board is transported.

　　(3) A good dry film can withstand PH=9 or above.

　　B Use the process test method to test the alkali resistance of the dry film or replace it with a new photoresist brand.

　　15. Problem: Over-etched wires in printed circuits become thinner

　　reason:

　　(1) The conveyor belt transmission speed is too slow

　　(2) When the pH is too high, side erosion will be aggravated

　　(3) The specific gravity value of the etching solution is lower than the standard setting value

　　Solution:

　　(1) Check the relationship between copper layer thickness and transmission speed, and set operating parameters.

　　(2) Check the pH of the etching solution. If it is higher than the range specified by the process, you can use enhanced ventilation until it returns to normal. (3) Check the specific gravity value. If it is lower than the set value, add copper salt and stop supplementing the sub-liquid. , so that the specific gravity value returns to the range specified by the process.

　　16. Problem: Insufficient etching in printed circuit and too large residual area

　　reason:

　　(1) The conveyor belt transmission speed is too fast

　　(2) The PH of the etching solution is too low (its value has little effect on the etching speed, but when the PH is lowered, the side etching will be reduced, but the residual foot will become larger)

　　(3) The specific gravity of the etching solution exceeds the normal value (the specific gravity has little effect on the etching speed, but when the specific gravity increases, the side etching will decrease)

　　(4) The temperature of the etching solution is insufficient

　　(5) Insufficient spray pressure

　　Solution:

　　(1) Check the relationship between the thickness of the copper layer and the transmission speed of the etching machine, and find out the optimal operating conditions through process testing.

　　(2) Detect the pH value of the etching solution. When the value is lower than 80, it is necessary to take measures to improve it, such as adding ammonia or accelerator liquid and reducing drafts.

　　(3) A detects the specific gravity value of the etching solution and adds more sub-liquid to reduce the specific gravity value to the process specified range.

　　B Check whether the sub-liquid supply system is malfunctioning.

　　(4) Check whether the heater function is abnormal.

　　(5) A. Check the spray pressure and adjust it to the optimal state.

　　BCheck whether there is any abnormality in the pump or pipeline.

　　C The water level in the liquid preparation tank is too low, causing the pump to run idling. Check the operating procedures for liquid level control, replenishment, and discharge of the pump.