PCB Conformal Coating

Conformal Coating PCB Services

At Sierra Assembly, we specialize in conformal coating PCB services designed to protect your printed circuit boards from environmental hazards, chemical exposure, dust, and thermal stress. With years of experience serving U.S.-based clients, we ensure that every board leaving our facility is reliable, compliant, and ready for high-performance applications. Whether your project requires silicone conformal coating, acrylic conformal coating, or black conformal coating, we provide tailored solutions for low, medium, and high-volume production.

What is PCB Conformal Coating?

PCB (Printed Circuit Board) conformal coating is a thin, protective polymer layer applied over electronic assemblies to shield them from environmental hazards and operational wear.

The coating conforms to the board’s surface, covering components, solder joints, and traces, while usually maintaining a thickness between 25 and 250 µm to ensure reliable protection without interfering with performance.

Types of Conformal Coating

 These coating types are selected based on your circuit board conformal coating requirements, device environment, and application.

Steps We Follow for Conformal Coating Application

Sierra Assembly employs multiple pcb conformal coating application methods:

1. Brush Coating: Ideal for small batches or selective coverage.
2. Spray Coating: Ensures uniform coating for medium volumes.
3. Dip Coating: Efficient for high-volume PCB production.
4. Automated Systems: For precision coating of fine-pitch components such as BGAs.

Before application, we mask sensitive areas like connectors or sockets to prevent interference. This step ensures accurate pcb coating while maintaining electrical performance.

We Measure Conformal Coating Thickness at Sierra Assembly

Accurate thickness measurement ensures performance and compliance:

• Wet Film Gauges: Measure immediately after application.
• Non-contact Instruments: Ultrasonic or eddy-current tools verify final coating thickness.

Typical coating thickness ranges from 25–75 µm (50 µm typical). Maintaining this precision is critical for protecting high-density BGAs and other complex components.

Steps We Follow for PCB Conformal Coating Curing

Proper curing of a conformal coating is critical to ensure a durable, reliable protective layer on your printed circuit boards (PCBs). The choice of curing method depends on the type of conformal coating being used acrylic, silicone, epoxy, polyurethane, or specialized UV-curable coatings. Here’s a breakdown of the main curing methods

1. Evaporative / Air Drying Curing: This is commonly used for acrylic conformal coatings. The solvent in the coating evaporates naturally at room temperature, leaving behind a uniform protective film.

2. Moisture Curing: Certain silicone conformal coatings cure through a reaction with moisture in the air. The process forms a flexible, durable film that is highly resistant to temperature extremes and environmental stress.

3. Heat / Oven Curing: This method is commonly applied to epoxy and polyurethane coatings. Coated boards are placed in an oven at controlled temperatures to accelerate the curing reaction.

4. UV Curing: UV-curable conformal coatings are applied and then exposed to ultraviolet light, which rapidly hardens the coating.

 
Choosing the right curing method ensures the circuit board coating adheres perfectly, prevents peeling, maintains reliability, and enhances the long-term durability of your assemblies. At Sierra Assembly, we match the curing process to the coating type and application, delivering consistent, high-quality PCB conformal coating services.

Our Conformal Coating Removal Process

Sometimes, it’s necessary to remove a conformal coating PCB layer to replace a damaged component, perform BGA repair, or conduct rework. The method chosen depends on the type of coating, the area size, and the sensitivity of components on the board. At Sierra Assembly, we ensure safe and precise removal, protecting Ball Grid Arrays, micro components, and the PCB itself.
 
Common Methods for PCB Coating Removal:

1. Solvent Removal: Many coatings, especially acrylic conformal coatings, can be safely dissolved with specific solvents. Harder coatings like epoxy, silicone, and polyurethane require specialized solvents, while parylene coatings generally cannot be removed this way.
2. Peeling: Flexible coatings, such as certain silicone conformal coatings, can sometimes be carefully peeled off small areas without harming the board.
3. Thermal / Burn-through: For precise local rework, a controlled soldering iron can burn through the coating over the targeted component, allowing quick access while keeping surrounding areas intact.
4. Micro blasting: For tougher coatings like parylene or epoxy, a gentle mix of compressed air and soft abrasives can remove coatings from small areas without damaging sensitive components.
5. Grinding / Scraping: Reserved as a last resort, mechanical abrasion removes hard coatings but requires caution to avoid damaging the PCB or its fine features.

At Sierra Assembly, we choose the safest removal method based on coating type and board layout, ensuring efficient rework, BGA reballing, or component replacement while maintaining board integrity.

Our Step-by-Step PCB Conformal Coating Process

1. Pre-Cleaning & Surface Prep: Remove dust, oils, and flux residues.
2. Masking:  Protect sensitive pads, connectors, and components.
3. Coating Application: Apply silicone conformal coating, acrylic conformal coating, or black conformal coating using the appropriate method.
4. Thickness Verification: Ensure consistent pcb coating using wet-film gauges or non-contact devices.
5. Curing: Air, oven, or UV curing depending on coating material.
6. Inspection & Testing: AOI, adhesion tests, and functional checks.
7. Final Delivery: Fully coated, tested, and ready-to-use boards.

Common Defects and Prevention

Quality Inspection of PCB Coatings

At Sierra Assembly, we integrate multiple inspections for circuit board conformal coating quality:

• Automated Optical Inspection (AOI):  Verifies uniform coverage and placement.
• Visual Inspection:  Detects bubbles, voids, or thin areas.
• Adhesion Testing: Ensures coating sticks securely.
• Environmental Testing: Humidity, thermal, and chemical resistance tests.

This layered approach guarantees reliable performance for all coated boards.

Benefits of PCB Conformal Coating

• Protects against moisture, dust, chemicals, and UV light
• Enhances thermal management for sensitive BGAs
• Reduces corrosion and electrical failures
• Supports miniaturized devices with circuit board conformal coating
• Allows safe BGA repair and BGA reballing

Why Choose Sierra Assembly

Customers choose Sierra Assembly because we combine technical expertise with reliable U.S.-based support and project management. Our team specializes in PCB conformal coating, including silicone conformal coating, acrylic conformal coating, and black conformal coating, ensuring high-quality protection for your boards.

Equipped with advanced AOI, X-ray, and precise thickness measurement tools, we maintain strict adherence to IPC-CC-830, MIL-I-46058C, ISO 9001:2015, and AS9100D standards. With extensive experience handling complex BGA designs and assemblies, Sierra Assembly delivers consistent, reliable results for every project.
 
Protect your PCBs with Sierra Assembly’s pcb conformal coating services. Whether you need silicone conformal coating, acrylic conformal coating, or black conformal coating, we deliver high-quality, reliable, and compliant circuit board coating solutions for your prototypes, low-volume production, or high-volume projects. Contact us today to discuss your requirements and request a quote.