What is Conformal Coating?
A conformal coating is a thin polymeric film applied to a printed circuit board (PCB) to protect the board and its components from the operating environment and corrosion. The film is typically applied at 25-250µm and ‘conforms’ to the shape of the board and its components, covering and protecting the PCB.
Prostech’s Conformal Coating Solution
Conformal Coating can be applied in a number of ways, including brushing, spraying, dispensing, and dip coating
Furthermore, many materials can be used as a coating layer, such as acrylics, silicones, urethanes, epoxies, and perylene. Initially, the material is coated onto the PCB in liquid form, then cure according to different mechanisms. Other specialist types of Conformal Coatings such as Parylene are applied differently. They are not liquid bases and are applied in a chemical vapor deposition process. Each has its own characteristics, making them preferred for certain environments and manufacturing scenarios.
Most circuit board assembly firms coat assemblies with a layer of transparent coating, which is lighter and easier to inspect. However, the colored coating can be used to secure the PCB design.
Conformal Coating can be applied in many industries such as electronics (handheld devices-pads, smartphones, speakers), automotive, military, air transportation, and medical devices.
Benefits and Purposes of Conformal Coating
The main purposes of the coating include:
Improving electrical properties of the PCB
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Insulation is a prerequisite for coating. The electronic circuit boards are more and more compact but must perform complex functions, resulting in high-density electrical interconnect packaging. A layer of Conformal Coating provides the PCB with insulation while increasing dielectric strength between the connections and components. |
Protecting the PCB from the harsh operating environment
With the strong growth of technology, PCBs are used in most industries, which means that sensitive PCBs are more and more exposed to hazardous environments such as moisture, dust and debris, corrosive agents, chemical substances, temperature extremes, etc,…These factors cause serious damage to the circuit board. Conformal Coating prevents those agents from harming the PCB by a layer of polymeric material. This material is resistant to chemicals, prevent contaminants as well as dust and debris from entering the PCB, and damages solder joint and components. It also prevents moisture from causing corrosion. The coating can provide resistance to environmental exposure, but they are not fully water-proof.
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| Uncoated PCB corrosion due to saltwater | No corrosion PCB thanks to Conformal Coating |
Contributing to heat dissipation
Temperature is the most influential factor in the failure of electronic components, so the PCBs must have effective thermal management. Organic coatings are seldom used for the primary purpose of conducting heat. Unfilled polymers and polymer coatings have low thermal conductivities. Filler can be used to increase thermal conductivities of the coating, but also decrease its insulation. Therefore, that method of increasing thermal conductivity is only used in some special cases. Normally, Conformal Coating is applied as thin as possible for easier heat transfer, since thermal conduction is inversely proportional to thickness.
Advantages and Disadvantages of Conformal Coating
Advantages of Conformal Coating
Among the electronic circuit boards protection solutions such as potting/encapsulating and low-pressure molding, conformal coating is different in its ability to protect the PCB with only a thin layer:
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Firstly, thanks to the thinness of the layer, it causes a minimum increase in the overall volume and size of the PCB. That is also useful for designs that require compact and tight, precise dimensions.
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At the same time, this thin layer also allows heat to be transferred from the PCB to the outside quickly, minimizing the risk of component failure or corrosion due to high temperatures.
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It’s also much easier to inspect and repair the PCB with conformal coating than with potting/encapsulant as well as low-pressure molding. We can easily observe the components on PCB through a transparent film.
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When necessary, the colored coating is used to secure the PCB’s design.
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A coating applies relatively little stress upon the components, this is a particular advantage where a component has thin pins or legs.
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Another advantage of Conformal Coating is that it provides a wide range of methods to apply. The manufacturer can choose the suitable method that fit the production scale and PCB’s requirements from manual brushing to automatic dispensing. The flexible processes can be easily done by the automated system. Initial investment costs will make the later production process efficient and economical.
Find out 06 common methods to apply conformal coating now.
Disadvantages of Conformal Coating
Besides the above advantages, there are some disadvantages of conformal coating that need to be considered in order to have a reliable coating:
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Although this method can protect the PCB from moisture, it is semi-permeable and not waterproof. Therefore, it is rarely used in environments exposed to a lot of moisture and water.
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Also, conformal contains VOCs within the solvents, though these are becoming less and less abundant.
- Lớp phủ bảng mạch cũng. không quá hiệu quả trong việc bảo vệ PCB khỏi rung động và va đập do màng này rất mỏng. Đối với các ứng dụng trực tiếp chịu các tác động của rung động và va đập, phương pháp potting/ encapsulating và đúc nhựa áp lực thấp sẽ được ưu tiên hơn.
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Conformal coating is not effective to protect the PCB from vibration and impact because of its thinness. For applications subject to frequent shocks and vibrations, potting/encapsulating and low-pressure molding are preferred.
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While can be done automatically, the process of Conformal Coating is quite long and complicated, requires meticulousness and precision.
Prostech understands the technical issues related to conformal coating for circuit boards and electronic devices. We offer comprehensive solutions, including consulting, materials, and automated adhesive application equipment. We have a global warehousing network to assist customers with logistics procedures. Positioned as a comprehensive supplier, Prostech is constantly striving to become a trusted partner for manufacturers around the world. Contact us by leaving your information below:
