Common problems and solutions of pvd vacuum coating equipment and daily maintenance of the pvd vacuum coating equipment

PART ONE

Common problems with vacuum coating equipment are mainly concentrated in three core scenarios: vacuum degree, film quality, and equipment operation. Targeted troubleshooting of parameters and components can efficiently solve these issues. The following is a detailed explanation:

I. Vacuum-related Issues (Core Impact on Coating Environment)
Question 1: The vacuum degree cannot be achieved or the pumping speed is slow
Reasons: Aging and damage of sealing parts (sealing rings, sealing rubber), contamination or insufficiency of vacuum pump oil, residual oil and water vapor inside the vacuum chamber, pipeline blockage or valve failure.
Solution: Replace the aged sealing parts and clean the sealing surface; Replace/replenish the vacuum pump oil and maintain the vacuum pump regularly. Clean the cavity and internal parts with anhydrous ethanol and dry them to remove moisture. Check if the pipeline is blocked and repair or replace the faulty valve.

Question 2: The vacuum degree cannot be maintained (prone to leakage)
Cause: The cavity door/flange is not tightly sealed. Observe that the seal at the connection between the window glass and the cavity has failed, and the pipeline joint is loose.
Solution: Re-tighten the cavity door and flange bolts to ensure there are no foreign objects on the sealing surface. Replace the gasket of the observation window; Check each pipe joint one by one, tighten the loose parts, and replace the joint seals if necessary.

Ii. Film layer quality issues (the most common, directly affecting product performance)
Question 1: Poor adhesion of the film layer (prone to peeling and scratching)
Reason: There are impurities such as oil stains and dust on the surface of the base, and the pre-treatment of the base is insufficient. The coating temperature is too low, and the film layer does not bond firmly with the substrate. The target material does not match the substrate material, or the sputtering power/pressure parameters are unreasonable.
Solution: Clean the substrate with ultrasonic waves before coating, and use plasma cleaning to remove surface impurities. Appropriately increase the substrate temperature (adjust according to the substrate tolerance); Replace the suitable target material, optimize the sputtering power and working air pressure, and extend the pre-sputtering time to remove the oxide layer on the target material surface.

Question 2: Poor uniformity of the film layer (inconsistent thickness/color)
Reasons: Uneven consumption of the target material (such as arc spots on the target surface), inconsistent distance between the substrate and the target material, uneven airflow distribution inside the cavity, and the substrate not rotating or moving at a constant speed during the coating process.
Solution: Regularly clean the arc spots on the surface of the target material and replace the target material if necessary. Adjust the position of the base frame to ensure that the distance between all bases and the target material is consistent. Check whether the gas pipeline is unobstructed and optimize the air intake method. Ensure that the base transmission system (such as the turntable) operates at a constant speed and repair faulty transmission components.

Question 3: The film layer has pinholes, particles and bubbles
Reason: The interior of the cavity was not thoroughly cleaned, leaving behind dust and particles. The purity of the target material is insufficient and it contains impurities. There are contaminants such as moisture and oil stains in the working gas. The coating rate is too fast and the gas is not discharged in time.
Solution: Regularly and thoroughly clean the cavity (including target material, base frame, and inner wall); Select high-purity target materials and working gases (such as argon with a purity of over 99.99%); Install a filtering device in the gas pipeline to remove moisture and oil stains. Appropriately reduce the coating rate and extend the vacuuming time.

Question 4: Abnormal color of the film layer (color deviation, darkening)
Reasons: The film thickness did not meet the design requirements, the composition of the target material deviated from the standard, the vacuum degree fluctuated during the coating process, and the substrate temperature was too high or too low.
Solution: Calibrate the film thickness monitor to precisely control the coating time and power; Replace qualified target materials; Check for leakage points in the vacuum system and stabilize the vacuum degree. Adjust the substrate temperature to the appropriate range (refer to the requirements of the target material and film layer type).

Iii. Equipment Operation Failure (Affecting Production Continuity)
Question 1: The sputtering target does not discharge or the discharge is unstable
Cause: RF/DC power supply failure, loose connection between the target material and the power supply, too low or too high working air pressure, severe oxidation on the surface of the target material.
Solution: Inspect and repair the power supply (such as replacing fuses, repairing circuit boards); Re-tighten the terminal blocks of the target material. Adjust the working air pressure to a reasonable range (usually 0.1-1Pa); Pre-sputter the target material to remove the surface oxide layer.

Question 2: Cooling system failure (Excessive temperature of the target material/cavity)
Reasons: The cooling water pipeline is clogged or leaking, the coolant is insufficient or the temperature is too high, and the cooling pump is damaged.
Solution: Unclog the cooling pipeline and repair the leaking part; Replenish the coolant (such as deionized water or special cooling oil), and check the heat dissipation effect of the cooling water tank. Repair or replace the faulty cooling pump.

Question 3: The transmission system is stuck (the base frame does not rotate, the conveyor belt does not move)
Cause: Motor failure, wear and loosening of transmission gears/belts, foreign objects jamming transmission components.
Solution: Inspect and repair the motor (such as checking the wiring and replacing the motor); Replace worn gears or belts and re-tighten the transmission components; Clear foreign objects from inside the cavity and in the transmission system.

PART TWO
This daily maintenance Checklist for vacuum coating equipment is classified by "daily/weekly/monthly", focusing on core components and key parameters, taking into account both practicality and operability, and is convenient for direct implementation

I. Daily Maintenance (Before startup and after shutdown, mandatory for each use)
Check the oil level of the vacuum pump to ensure it is between the scale lines, and the oil color is not turbid or black.
Clean the surface of the vacuum chamber and the observation window, remove dust and fingerprints to avoid affecting the observation and sealing.
Check the cooling system: The coolant level is normal, there is no leakage or blockage in the pipelines, and the cooling pump operates without abnormal noise.
Inspect the sealing parts (cavity door, flange sealing ring) : no damage or deformation, no oil stains or impurities on the surface. If necessary, wipe them with anhydrous ethanol.
Confirm the gas pipeline: The valve opens and closes flexibly, there is no leakage, and the pressure of the working gas (such as argon) is sufficient.
After shutdown, clean the surface of the target material: Remove the surface oxide layer through pre-sputtering, and turn off all power and gas valves.

Ii. Weekly Maintenance (Regular inspection to prevent minor hazards)
Check the transmission system: The base frame and conveyor belt operate smoothly without jamming or abnormal noise, and the gears/belts are not loose or worn.
Clean the interior of the cavity: Wipe the cavity walls and base frame with a lint-free cloth to remove any remaining target material debris and particles.
Check the power connection: The terminals of the RF/DC power supply are not loose or overheated, and the insulation layer of the cable is not damaged.
Test the vacuum pumping speed: Record the time it takes to evacuate the vacuum to the target vacuum degree, compare it with the standard value, and determine whether there is any leakage or a decrease in the pump body efficiency.
Check the auxiliary components: The film thickness monitor, pressure gauge and other instruments display accurately and have no abnormal alarms.

Iii. Monthly Maintenance (Deep servicing to Extend Equipment Lifespan)
Change the vacuum pump oil: Completely drain the old oil, clean the oil tank, and add new special vacuum pump oil (matching the model as per the equipment manual).
Inspect and replace the sealing parts: Replace the aged and hardened sealing rings and gaskets to ensure the sealing effect.
Clean the gas filter: Replace or clean the filter element in the gas pipeline to remove impurities such as moisture and oil stains.
Calibrate key parameters: Calibrate the film thickness monitor and vacuum gauge to ensure coating accuracy; Check the consumption of the target material and replace it if necessary.
Thoroughly clean the equipment: Remove the dust and oil stains inside the equipment, check the ventilation of the circuit junction boxes and control cabinets to prevent overheating.
Record the operation data of the equipment: summarize parameters such as vacuum degree, sputtering power, and coating time, establish maintenance files, and facilitate subsequent fault traceability.

Iv. Maintenance Precautions
1.All maintenance operations must be carried out after power and gas supply have been cut off to avoid the risk of electric shock or gas leakage.
2.When cleaning, do not use corrosive solvents. Give priority to using special consumables such as anhydrous ethanol and lint-free cloths.
3.When replacing components (such as target materials and seals), ensure that the model matches and they are installed properly.
4.If any abnormality is detected (such as a sudden drop in vacuum degree, abnormal equipment noise, or alarm), stop the machine immediately for inspection. Do not continue to use it until the fault is eliminated.