Technical Q&A: Conformal Coating System
 

1. How can nozzle clogging and skinning issues be resolved?
2. What causes bubbles after automated coating, and how can they be eliminated?
3. How can spray edge definition be precisely controlled?
4. What causes uneven coating thickness?
5. How do I choose the right valve?
6. What is the principle and importance of UV inspection?
7. How does fluid viscosity affect automation?
8. What is the maintenance frequency and what are the consumables?
9. Should I choose an In-line or Off-line coating system?
10. How can "Capillary Action" be prevented?


1. How can nozzle clogging and skinning issues be resolved?

A： Conformal coatings (such as silicone, acrylic, or polyurethane) cure easily when exposed to air. You should regularly inspect the automatic soaking and wiping systems. If the machine is idle for an extended period, the nozzle should be placed in a solvent cup. Additionally, use moisture-proof air filters to ensure the air lines remain dry, preventing material reaction inside the valve body.


2. What causes bubbles after automated coating, and how can they be eliminated?

A： Bubbles typically result from excessive spray pressure, rapid solvent evaporation, or over-agitation of the fluid. To fix this, reduce atomization pressure, increase the flash-off time, or perform a de-bubbling (degassing) process on the coating material before application.


3. How can spray edge definition be precisely controlled?

A： Users often encounter "overspray" on restricted areas like connectors or gold fingers. The key lies in nozzle selection and height control. Using a Film Coat valve provides sharp edges. Pair this with a CCD vision alignment system to automatically compensate for PCB positioning shifts. For critical areas, physical fixtures or masking tape can also be used for protection.


4. What causes uneven coating thickness?

A：This is usually caused by inconsistent movement speeds or fluctuations in viscosity. You should install a constant temperature system to stabilize viscosity and perform regular weight calibrations to ensure the flow rate per unit of time remains consistent. Using smaller syringes/cartridges can also reduce the range of viscosity changes over time.


5. How do I choose the right valve?

A：
Spray Valve: Ideal for large areas and thin coatings.
Conformal Valve: Best for high efficiency and sharp edge definition.
Needle Valve: Suitable for gap filling or precision dispensing.

EP conformal coating system support multi-head configurations, allowing one machine to handle both high-speed coating and fine dispensing simultaneously, increasing production flexibility.


6. What is the principle and importance of UV inspection?

A：Most conformal coatings contain UV fluorescent tracers. Coating machines are typically equipped with UV light sources and vision cameras to detect missed spots. If the coating glows blue under blacklight, coverage is complete. This is a critical component of automated Quality Control (QC).


7. How does fluid viscosity affect automation?

A： If viscosity is too high, the material won't atomize properly; if it's too low, sagging (dripping) occurs. It is recommended to maintain viscosity between 50 to 300 cps. If ambient temperatures fluctuate significantly, a heating device is mandatory.


8. What is the maintenance frequency and what are the consumables?

A： Check nozzle cleanliness daily; clean filters weekly; and replace O-rings every six months. Primary consumables include nozzles, sealing components, and cleaning solvents.。


9. Should I choose an In-line or Off-line coating system?

A：
In-line: Best for high-volume production; integrates directly with SMT lines to save labor.
Off-line: Ideal for high-mix, low-volume (HMLV) production, R&D, or varying PCB sizes. It also has a smaller footprint.

The iL series offers flexible configurations for both in-line and off-line applications to meet diverse market demands.


10. How can "Capillary Action" be prevented?

A： Capillary action occurs when coating seeps into connectors due to low viscosity or excessive volume. To prevent this, increase fluid viscosity, reduce spray pressure, or apply a "dam" (a high-viscosity barrier) around sensitive components before the main coating process.