Requirements of PCBs after conformal coating:
1. The surface of the circuit board can not have the phenomenon of paint flow, leakage, and semi-wetting.
2. The three anti-paint layer should be smooth, bright and even in thickness, and the surface of the pad, stick element or conductor should be well protected.
3. No orange peel, bubbles, pinholes or ripples on the surface of the paint layer.
4. Do not paint the components or components that do not need protection.
5. The printed board shall be clean and tidy after the three protection, and there shall be no damage of components.
6. No dirt, fingerprints, ripples, shrinkage holes, dust and other defects and foreign objects on the board and components, no powder, no peeling phenomenon.
Which products are PCB Conformal coating mainly used for?
Venture Team has many clients whose projects require the use of Conformal coating.
Their products are mainly applied to tropical electrician products, relay, LED circuit board, navigation instrument panel, thermal instrumentation, precision instruments, carrier communication control panel, security of electronic circuit boards, vehicle-mounted motherboards, computer motherboards, lighting lamps and lanterns of circuit board, LED electronic control board, inverter control panel, power panel electronic components of the protective and motor protection, etc.
Are there any components on PCB that cannot be brushed and painted with Conformal coating?
1. High power components with cooling surface or radiator, power resistor, power diode, cement resistor.
2. Dip switch, adjustable resistance, buzzer, battery seat, safety seat (tube), IC seat, touch switch.
3. All types of sockets, pins, terminals and DB terminals.
4. Plug or stick light-emitting diode, digital tube.
5. Other parts and devices that are not allowed to use insulating paint as specified in the drawings. The screw holes of 6PCB card cannot be coated with Conformal coating.
Venture PCB Conformal Coating ensures reliable performance of electronics nowadays. Venture can continue to deliver pinhole-free and ultra-thin electronics coatings that meet industry needs.
Venture has been 10 years in providing world-class PCB conformal coating services to clients within aerospace, electronics, marine, defense, and space exploration industries.
Venture PCB conformal coating ensures trouble-free performance and component reliability the industry demands.
Your Leading PCB Conformal Coating Supplier in China
Venture PCB Conformal coating is a thin film of protective material applied to a circuit board. Venture is a professional PCB conformal coating in China for more than 10 years.
Our PCB conformal coating services cover the entire board and protect both the parts and the board including the solder joints, exposed traces, component leads, and other areas of exposed metal.
Venture PCB conformal coating is designed to protect the metal from corrosion. It also shields the entire board from moisture, spray, dust, fungus, and other contaminations from harsh environments.
Additionally, PCB conformal coatings help prevent damage from mechanical and thermal stress and as well as rough handling helping to extend the life of the PCB.
As a professional in handling PCB conformal coating, we offer different kinds of conformal coating for your PCB. These are:
- Acrylic Resin (AR)
- Silicone Resin (SR)
- Urethane Resin (UR)
- Epoxy Resin (ER)
At Venture, we are always ready to work with you on your PCB manufacturing and recommending which conformal coating will best suit to your PCB needs.
We have more than 10 years of experience doing this. We have the resources you need in order to ensure that your design is manufactured to the highest levels of quality.
If you want more information on Venture PCB conformal coating standards, please don’t hesitate to contact us now!
Conformal Coating Types: The Ultimate FAQ Guide
I know you’d like to learn more about conformal coating types in PCB fabrication.
Well, this guide has every information you are looking for – keep reading.
- What is Conformal Coating in PCB?
- Why is Conformal Coating Important?
- What are some of the Common Conformal Coating Types?
- What Influences the Choice of Conformal Coating used on PCBs?
- Why are Urethane Resins used as Conformal Coating?
- What are the Shortcomings of using Urethane Resins as Conformal Coating for PCBs?
- What are Acrylic Resins?
- Why is the use of Acrylic Resins as Conformal Coatings Limited?
- What are the Features of Epoxy Resin as a Conformal Coating?
- Where is Silicone Resin used as a PCB Conformal Coating?
- How is Parylene Coating Applied on PCBs?
- What makes Parylene Coating a favorable choice for PCBs?
- Are all Conformal Coatings Solvents?
- What are Hybrid Conformal Coatings?
- Can Conformal Coatings be Water-based?
- What are the Qualities of UV Cure Conformal Coatings?
- Are Two Part Conformal Coatings made Thicker than their Single Part Counterparts?
- How does Poly-para-xylelene compare with Fluorinated poly-para-xylelene Coating?
- What is Amorphous Fluoropolymer Coating?
- Is Conformal Coating Waterproof?
- Where are Conformal Coatings useful?
What is Conformal Coating in PCB?
Conformal coating refers to a protective layer that is used over the PCB surface adapting to the board’s features.
The protection it offers the board is against external elements in the environment such as moisture and dust, and also deterioration.
You find this coating is made from polymers, notably resin, consequently serving as an insulator to the circuit board.
A conformal coat is typically a very thin layer that does not usually exceed 250µm.
It blankets in its protection, the joints resulting from the solder process, bare conductive paths, component leads and metallic features.
Use of conformal coating increases a PCB’s durability.
Why is Conformal Coating Important?
You find a number of benefits derived from using conformal coating on printed circuit boards.
Some of these advantages are described below:
- Without conformal coating, the PCB is at the mercy of environmental elements such as dust and moisture.
When such elements accumulate on the board surface they could hamper its performance by interrupting electrical paths and causing molding.
- You can achieve high value voltage gradients by using conformal coating while also reducing the space between conductive traces.
As you will find, the layer circuit density is increased this way allowing for smaller board formations with increased performance.
- Since conformal coating adheres to the PCB features, you find it has reduced space requirements.
Therefore, this coating approach does away with the requirement of elaborate packages for the PCB.
- The conformal coating is not bulky and as such weighs very little.
You, therefore, find using conformal coating does not add to the overall board weight in the process.
- Since the coatings are made from polymers they are poor electrical and thermal conductors.
As a result, you find these coatings contribute to thermal management.
Their use allows narrower spaces between conductive traces increasing the layer’s circuit density.
- A bare circuit board when left exposed can be subject to unwanted chemical interaction such as spillage.
Applying conformal coats helps ensure the board is safe from such interactions that could result in corrosion.
What are some of the Common Conformal Coating Types?
You find several conformal coatings presently used for PCBs in the industry.
These coatings can be placed in several different categories based on their highlighting features such as their chemical structure.
A common chemical substance present in many conformal coatings and used in their classification is resin.
In this regard you find the following types of conformal coating:
Conformal coating on PCB
- Acrylic coating
- Silicone coating
- Epoxy coating
- Urethane coating
What Influences the Choice of Conformal Coating used on PCBs?
Choosing a conformal coating for you printed circuit board is not entirely a matter of preference.
You need to consider a few factors to ensure you make the appropriate material selection.
Some of the important aspects to weigh your decision include:
- The area of application of the printed circuit board.
- The functional requirement of the PCB.
- The environment in which the PCB will be used.
- The ease of application of the coating.
- The ease of rework on the coating.
- The compatibility of the coating with the PCB properties such as CTE.
- The duration it takes for the curing process.
- The cost of carrying out the coating process.
Why are Urethane Resins used as Conformal Coating?
Urethane resin are structurally fashioned on a single particulate or dual constituents.
You find the use of urethane resins is on the strength of their resistance to moisture and chemical substances.
Conformal coating on PCB
Moreover, the resulting coating formed from urethane is hardly unaffected by abrasion.
You also find urethane coatings to offer impressive dielectric aspects to the printed circuit board.
Furthermore, the chances of reverse potential occurring with this coating are minimal.
What are the Shortcomings of using Urethane Resins as Conformal Coating for PCBs?
When using urethane resins as conformal coating for PCBs the following disadvantages are observed:
- When applying this coating, you find that the curing process is extended taking up to four weeks.
Additionally, you discover the moisture content in the atmosphere influences the rate of curation and final coating characteristics.
- You find removing urethane coatings to be an arduous process. In addition, this coating type is not entirely safe on exposure posing health risks.
- The coating resulting from urethane resins comes off at some parts.
Moreover, when a soldering iron is used on this coating during rework, brown colour tints are observed on the surface.
- When you use urethane coating, chances are they will succumb to stress when subjected to continuous temperature cycles.
Subsequently, you find these coatings can return to original state.
What are Acrylic Resins?
Acrylic resins are single element polymers based on acrylics that have been developed and ionized in solutions.
These resins are widely available and easy to work with since their application and removal is not a difficult task.
Furthermore, when acrylic resins are cured they do not shrink and take a relatively short time to dry.
The resistance ability of acrylic resins to humidity is remarkable and so is its response when its viscosity is altered.
You also find the fluorescence level is high for this coating type.
Why is the use of Acrylic Resins as Conformal Coatings Limited?
While acrylic resins are an affordable alternative when it comes to conformal coatings, its use is limited in certain ways.
Some notable limitations are as follows.
- You find acrylic-based conformal coatings are affected by chemical interactions such as acids.
- Additionally, these coatings are easily prone to mechanical wear and tear.
- Acrylic coatings are affected by high temperature and are therefore not suitable for PCBs used in such usage.
- Extreme environments of temperature and humidity negatively hampers the usefulness of acrylic coating as they can revert to original state.
- Their ease of response to alteration of viscosity makes the task of maintaining it at a certain level tough.
- You find this coating can easily catch fire resulting in its destruction.
What are the Features of Epoxy Resin as a Conformal Coating?
Epoxy-based coats have various outstanding features that contribute to their use or disuse.
For instance, these coats are preferred for these reasons.
Applying conformal coating
- Their impressive durability even in extreme environment usage. This feature allows these resin type to hold at temperatures of up to 150 o
- Epoxy coatings are hardly affected by chemical interactions and moisture.
- The coat provided by epoxy resin can tolerate mechanical wear.
- Also, the dielectric quality of epoxy resin is impressive with a coefficient of thermal expansion that matches the PCB’s laminate.
However, epoxy resins are made developed through making elaborate chemical mixtures that are not easy to comprehend.
Furthermore, this coating is highly rigid entailing a demanding process to control its viscosity.
It also succumbs to stress during thermal cycles which increases chances for its return to original state.
There pair and removal of epoxy-based coats is found to be grueling with a high risk of contamination with chlorides.
Additionally, when curing this PCB coating, shrinking occurs deforming the coat surface.
You also find there is need for using solder iron when reworking which causes tint formation.
Where is Silicone Resin used as a PCB Conformal Coating?
Silicone resin is a mono-structured substance that finds use in PCB applications destined for extreme temperature usage.
You find silicone resins make conformal coatings that resist atmospheric moisture content and solvents with strong pH.
Consequently, a silicone coating cannot be easily eroded.
You also find silicone resins are unaffected by ultraviolet radiation.
Their flexibility levels allows for protection against mechanical shocks.
Silicone resins used as coatings have good dielectric properties.
Furthermore, you realize the conformity of the silicone resin to the PCB surface and features is relatively high.
However, removing a silicone resin coat is a demanding task involving a rigorous process with concentrated solvent removers.
You can also only carry out rework at select board areas with silicone-based coatings.
While curing of silicone coating is dependent on humidity levels, it offers minimal protection in the face of solvent interaction.
How is Parylene Coating Applied on PCBs?
Parylenevaporizes when subjected to heat, consequently, its application is notably different from other coatings referred to as chemical vapor decomposition.
You need a specialized assembly that includes a vacuum chamber to carry out the chemical vapor decomposition process.
Parylene vapor is cooled and fed to the vacuum chamber where, in the absence of matter, polymerization takes place.
As a result, a film is formed after which it is applied over the PCB.
This film adheres firmly over the PCB surface requiring painstaking efforts to remove it.
Furthermore, it cannot be exposed in open environment for long without deteriorating.
What makes Parylene Coating a favorable choice for PCBs?
Use of parylene as a PCB conformal coating is grounded on several desirable properties it has.
Some of these properties include:
- Parylene offers a very impressive solvent choice with its ability to tolerate high temperatures and harsh application environment. Its temperature tolerance is observed to be the best among other resin based coatings.
- You find this type of coating is transparent allowing you an unobstructed view of the board features with remarkable dielectric qualities.
- Additionally, parylene is developed at room temperature eliminating the need for long curing process.
Are all Conformal Coatings Solvents?
Not all conformal coatings are derived from solvents, however solvent-based coatings are more common in industry.
The popularity of these coating types results from the following features.
- Conformal coatings derived from solvents are easy to process and subsequently apply on the printed circuit board.
- You can easily adjust the viscosity of conformal coating solvents to achieve a particular desired fluidity for your application.
- Solvent-based conformal coatings are adaptable for a variety of uses.
- The curing process of conformal coatings derived from solvents is straight forward without many complexes.
What are Hybrid Conformal Coatings?
Hybrid coatings are developed through the chemical combination of different base substances.
With this approach, you find the resulting coating is a precise outcome of certain desired features to suit a particular use.
For example, silicone and urethane resins can be combined to develop a coating with higher thermal resistance.
When you utilize hybrid coatings for PCBs, you benefit from better features and performance than conventional types.
These coatings are also easily applied due to their solvent form.
They offer improved resistance to chemical infraction allowing rework through the use of specialized equipment.
Hybrid coating can also support use in different environmental conditions.
Can Conformal Coatings be Water-based?
Yes, they can.
Conformal coatings that are water-based have come to existence to reduce the negative impact of organic solvents on the environment.
These coatings are an example of hybrid coatings cured through an evaporation process that removes water molecules.
Consequently, it differs from solvent-based coatings by recording fewer solvent-related releases into the atmosphere.
However, the drying process of water-based coatings is slow with the possibility of cracks increasing with the thickness of the coating.
Furthermore, not all PCB applications will be favorable for such coatings to be effectively used.
Nonetheless, several advantages are derived from water-based conformal coatings such as:
- Eliminating large use of organic solvents allows for reduces emissions that are harmful to both the environment and personal health.
- These coatings do not require special equipment to be used in their application. They are instead compatible with the typical equipment used for the other coatings.
- The resistance of these coatings to chemical infringements is commendable while also offering decent performance.
What are the Qualities of UV Cure Conformal Coatings?
With UV cure conformal coatings, ultraviolet radiation is used in the curing process.
This process takes a short time of less than a couple seconds faster than any other coating.
Subsequently, their use is favored for large production cycles.
You find the ultraviolet radiation can miss out on PCB surface parts that are obstructed by components and other board features.
This is called the shadow effect which and to complete curing for these parts, another curing process is carried out.
Conformal coating on PCB
UV cure conformal coatings are can demonstrate limited stiffness when subjected to different temperature environments.
Consequently, these coatings require elaborate test procedures.
However, the following qualities are associated with these conformal coating type:
- These coatings are developed considerably quickly allowing their use in large production cycles.
Ultraviolet radiation takes only a few seconds to complete the curing process for a single board.
- Additionally, you can use an ancillary curing process to cater for the locked out areas during the UV cure.
A thermal or moisture cure can suffice.
- UV cure conformal coatings provide decent PCB surface protection from the elements in different environments.
Their ability to resist chemical intrusion is also remarkable.
Are Two Part Conformal Coatings made Thicker than their Single Part Counterparts?
Two part coatings can be made thicker than single part coatings albeit not as a necessary measure.
When you use two part coatings, you blend multiple resins with different features to derive one with several desirable qualities.
Consequently, the resulting coating possesses enhanced features for better board protection.
Furthermore, these two part coatings are as easy to process as single part coatings with a similar price range too.
Their performance levels are much higher and so is their functionality across different environments.
Their resistance to moisture content is also impressive.
How does Poly-para-xylelene compare with Fluorinated poly-para-xylelene Coating?
The fluorinated poly-para-xylelene differs mainly from the regular poly-para-xylelene in the material constitution where it is added fluorine compounds.
Furthermore, you find the coating process for fluorinated poly-para-xylelene is slower requiring specialized equipment to conduct the application process.
Additionally, the fluorinated poly-para-xylelene has better dielectric properties with a much higher thermal stability.
Both these resins are chemically inert indifferent to interactions with both basic and acidic solutions.
They offer an exceptional uniform surface with limited absorbency.
Nonetheless, you will find both these resin types require batch processing for the boards in enclosures of vacuity.
Also, where there is to be no coating a mask is required to shield the area making the process long.
You will also need specialized devices to remove these coatings and also rework them.
Poly-para-xylelene has a reduced weight measure with limited emissions and as a result is less of a threat to the environment.
It also finds employment in medical equipment due to its adherence to biological aspects.
However, this coating resin is not suitable for doping and is easily affected by ultraviolet radiation and extreme temperatures.
What is Amorphous Fluoropolymer Coating?
Amorphous fluoropolymer is a resin-based coating that features impressive dielectric qualities and high working temperature.
PCB conformal coating
Also, the absorption rate of water for this coating is low similar to its surface energy.
You also find this coating type to be less affected on interaction with chemicals and oils.
Nevertheless, amorphous fluoropolymer coating is dependent on certain specific solvents for its development in polymerization.
Its reduced solubility is a hindrance in achieving thicker films.
The surface established with this coating also requires to be treated while it still exhibits low adhesion.
Is Conformal Coating Waterproof?
As a general observation, you find many conformal coatings are not waterproof save for parylene resin coating.
The coating surfaces can allow for the penetration of water molecules onto the board surface where they can cause corrosion problems.
Consequently, it is necessary as a precaution measure to avoid direct interaction of the board with water.
Where are Conformal Coatings useful?
Conformal coatings offer the printed circuit board from contaminants such as moisture and dust particles.
Common areas where conformal coatings find significant application are as follows:
You find conformal coatings useful on analogue circuits where high signal quality is needed.
Coatings keep off contaminants which could result in faint conductivity that could alter the quality of the signals.
Additionally, coatings can offer on board semiconductor chips relief from physical shocks and thermal induced stress.
Such stresses can result from intense vibrations. Coatings can safeguard the thin wire connections preventing them from breaking apart.
You will also find conformal coatings useful in areas where there is high circuitry.
In such instances, the insulating property of the coatings offers a shield to the electric field formations.
For any inquiries or questions about conformal coating types, contact Venture Electronics now.