Want to know how conformal coating machines work and how they can safeguard and enhance the reliability and performance of electronic devices? Keep reading this blog to find out the answer!
In the landscape of miniaturized electronics and circuitry, conformal coating machines stand out as a crucial element in preventing PCBs from adverse conditions. They are the skin of the electronic industry, ensuring that electronic devices remain protected from environmental factors, corrosion, component failure, dendrite growth, and more.
Additionally, the conformal coating machines work to extend the device’s life, improve reliability, and reduce warranty claims. They can handle PCBs of any type and size, whether used in electronic consumer products, communication equipment, automotive electronics, medical equipment, and more, making them a versatile solution for various industries.
Conformal Coating Machines & How It Works: A Brief Overview
A Conformal Coating Machine is a multi-phase robotic system that altogether works to coat the PCB surface with a thin polymeric film. The film is typically 25-250 µm and “conforms” to the design of the board and its components. It dust-proofs, water-proofs, and prevents the device from corrosion damage and other adverse environmental factors. Keep reading to know how conformal coating works!
Conformal Coating Process
Now that you know what a conformal coating machine is, let’s understand how it works! Below is the step-by-step process suggesting the various phases of conformal coating!
1. Preparation Phase
Cleaning the PCB: The PCB is meticulously cleaned to remove the traces of dust, dirt, grease, or flux residues, ensuring seamless adhesion of the resin on the PCB’s body
Masking the PCB: Some areas or elements in the PCBs including connectors or test points need not be coated; hence these are masked using tapes or caps
2. Choosing the Coating Type
The next phase in the conformal coating process is choosing the right coating material. Also, take into account factors such as coating thickness, machine speed, ambient temperature, and humidity levels to ensure that the PCB is coated well.
Given below are some of the popularly used conformal coatings, along with their unique characteristics, properties, and benefits.
Acrylic-Based Coatings: With their exceptional UV and moisture resistance properties, acrylic-based coating works well for circuit boards exposed to direct sunlight.
- Suitable Application Type: Dipping, Spraying, and Brushing
- Removal Method: Using non-aggressive solvents like isopropanol if the circuit needs to be modified.
- Limitations: Shows the least resistance towards solvents and can’t sustain temperatures over 250 degrees Fahrenheit.
Silicone-Based Coatings
With excellent flexibility and high-temperature resistance, silicone-based coatings are ideal for circuit boards operating in extreme temperature environments.
- Suitable Application Type: Dipping, Spraying, and Brushing
- Removal Method: Using specialized solvents or abrasion methods due to strong adhesion.
- Limitations: Lower abrasion resistance and longer curing times compared to other coatings.
Polyurethane-Based Coatings
Polyurethane-based coatings are well-suited for circuit boards exposed to harsh chemicals and mechanical stress.
- Suitable Application Type: Dipping, Spraying, and Brushing
- Removal Method: Requires aggressive solvents like methylene chloride for removal.
- Limitations: Susceptible to moisture absorption during curing and turn yellow over time with UV exposure.
Epoxy-Based Coatings
Providing exceptional chemical, moisture, and abrasion resistance, epoxy-based coatings are ideal for circuit boards requiring a tough, protective barrier.
- Suitable Application Type: Dipping, Spraying, and Brushing
- Removal Method: Difficult to remove; typically requires mechanical abrasion or aggressive chemical solvents.
- Limitations: Rigid and brittle, making them prone to cracking under thermal stress.
Hybrid Coatings
Constituting the best properties of multiple coating types, hybrid coatings offer enhanced durability, flexibility, and environmental protection.
- Application Type: Dipping, Spraying, and Brushing
- Removal Method: Varies depending on the composition, often requiring a combination of solvents and mechanical methods.
- Limitations: Performance characteristics depend on formulation, and cost may be higher than single-type coatings.
3. Application of Coating
In the next step, the conformal coating machine coats the PCB using one of the following approaches!
- Spray Coating: In this method, a spray nozzle, which is crucial conformal coating equipment, is put in action to coat the PCB in a controlled manner.
- Selective Coating: Often done when there’s a need to perform precise coating. The conformal coating machine uses robotic nozzles to coat specific areas of the PCB.
- Dip Coating: In this method, the PCB is dipped into a bath of conformal coating material, covering the entire surface. Masking is critical here to protect unwanted areas.
4. Drying the Coating
The next step in the conformal coating process is to dry/harden the PCB Coating. The various methods include:
- Thermal Curing: Also known as oven curing, it works by making the oven work in tandem with the conformal coating machine. It’s done by placing the PCB in an oven to dry the coating.
- Infrared Curing: It is done by exposing PCBs to infrared radiation. Although it can be faster than traditional oven curing, it needs to be closely monitored to prevent the PCB from overheating.
- UV Curing: Depending on the PCB’s heat resistance capacities, the PCB is exposed to the UV light.
- Moisture Curing: Coatings cure by reacting with ambient moisture, which may take longer.
5. Inspection and Quality Control
After curing, the coated PCB is inspected for uniformity, coverage, and defects. This is often done using UV light, as most coatings fluoresce under UV for easy inspection.
6. Post-Coating Process
Based on the flaws identified in the inspection phase, the PCB is taken for rework or repair. The flaws are all fixed to ensure consistency in the coating.
7. Demasking and Cleaning
Masking materials are removed, and any residue is cleaned off. The PCB is now ready for further assembly or use.
Types of Conformal Coating Machines and Their Functions
When it comes to deciding what type of conformal coating machine can work well, take a step back and reconsider your requirements. Take into account factors such as automation level, precision, and application method. Below listed are a few conformal coating machines, along with their functions:
1. Selective Coating Machines
- Function: It works precisely by applying the conformal coating to specific areas of a PCB, avoiding connectors and other sensitive components.
- Best For: Ideal for PCBs used in automotive, aerospace, and medical electronics industries, where precision is critical.
HJE Tech offers a top-rated selective conformal coating machine HTF-450B that’s ISO certified, cost-effective, easy-to-use, and ensures smooth operation.
2. Dip Coating Machines
- Function: This type of conformal coating machine submerges the entire PCB into a tank of conformal coating, ensuring complete coverage. Excess coating drips off before drying.
- Best For: PCBs requiring coating on all surfaces, including hard-to-reach areas.
3. Robotic & Fully Automated Coating Systems
- Function: It is a state-of-the-art and fully automated system that controls the entire coating process, from application to curing.
- Best For: It is a high precision, efficient, and one-of-a-kind coating system that in-lines the entire coating process.
Final Words
Conformal coating machines play a key role in safeguarding the circuit board against environmental conditions, preventing corrosion, reducing mechanical stress, and preventing dendrite growth.
However, the results depend a lot on the type of conformal coating machine, the used conformal coating, and the selected curing method. For instance, some circuit boards have terminals that may not perform well with coating; here selective conformal coating machines can work well. On the other hand, if there’s a circuitry requiring precision, one may should go with Robotic & Fully Automated Coating Systems.
If you’re looking for top-rated, ISO certified Conformal Coating Machines, then look no further than HJE Tech India Private Limited. We deliver nothing less than perfection to our clients. Get in touch to know more about our products or services.
Frequently Asked Questions (FAQS) About Conformal Coating Machines and Their Types
What is the main purpose of Conformal Coating Machines in the electronic industry?
The Conformal Coating Machines are primarily used to apply a thin layer of resin onto PCBs, protecting them against the impacts of moisture, dust, chemicals, etc.
What factors should I consider when choosing a Conformal Coating machine?
When selecting a conformal coating machine, consider the following factors:
- Desired Coating Thickness
- Application Method
- Operating Temperature Range
- Compatibility with Existing Manufacturing Process
- Budget
Disclaimer– The information provided in this content is just for educational purposes and is written by a professional writer. Consult us to learn more about high-quality SMT/DIP solutions and services for electronics manufacturing businesses.