- What are the Benefits/Functions Of Conformal Coatings?
Conformal coatings are essential for enhancing the reliability and long-term performance of electronic assemblies. They provide superior protection against:
- Mechanical stress
- Shock and vibration
The primary function of conformal coating is to prevent the electronic circuit boards from long-term corrosion due to moisture condensation. Other desirable features include a better prevention of electrical shorts in high humidity days.
- Why use a Conformal Coating?
Due to the decrease in size of PCBs and the increased packing density, there is increase in the chance of shorts, corrosion, dendrite growth and electro migration. Conformal coating a PCB can improve the long term reliability of an assembly through careful application (and selective robotic application is the best for this).
Conformal coatings are defined as thin polymeric films that conform to the surface of the printed circuit board (PCB) and components. The conformal coating acts as an insulator. It protects the electronic circuits from the environment including moisture ingress and contaminants such as airborne dust which could lead to corrosive effects and shorts, as well as providing mechanical strength for vibration and shock.
- Why not mask and spray paint my boards?
While spray painting or submerging PCB boards may seem like an easy and cost effective way to create conformal coatings – this works for some builds, however taking into an account the time spent masking and removing masking, no-uniformity – makes robotic selective coating a much more viable and accurate solution that reduces board loss and coating wastage .
- If I have protected my electronics in a sealed plastics and metal boxes but the electronics are used outdoor, do I still need to conformal coat my circuit boards inside the sealed box?
Having a sealed electrical box is good for rain. Moisture can still pass through the plastic boxes and rubber gasket. In fact, sealed boxes do not “breathe” and thus trapped moisture that cannot escape and will condense to become sitting water inside the box at night or colder weather. Condensed with potentially contaminating ionics from the air is one of the most potent corrosive ingredient.
- We are required to use a Conformal Coating that are UL recognized. Do you have any UL recognized Conformal Coatings?
Yes we have a great many Coatings that are recognized under the Component Program of Underwriters Laboratories, Inc., File Number E 105698.
- Do you have coatings that meet the military specification and are military qualified?
Yes, in fact we have many coating products that are qualified by the Military´s MIL-I-46058C specification
- Is Out-Gassing an issue with Conformal Coatings?
Some conformal coating materials out-gas and can cause conformal coating failures. The effect can occur in a vacuum or when the conformal coating is heated, which can result in conformal coating material volatizing and re-depositing on sensitive components. We use the following conformal coating materials meet and or exceed NASA specifications for out-gassing:
- Arathane 5750 by Huntsman
- Aptek 2503 by Aptek Labs
- Solithane 113 by Crompton-Uniroyal Chemical
- CE-1155 by Cytec Industries
- I have reviewed your website and can find no mention of a Parylene coating. What is it and do you provide it?
Parylene, also know as Polyparaxylelene, is a very good Conformal Coating that applies by a vapor deposition process. However Parylene is also a very expensive coating. Not only is the material itself expensive, the equipment required to apply Parylene is also expensive. Parylene is vacuum deposited onto the assembly and one application cycle can require many hours to complete. Due to its cost and application issues, Parylene does not readily lend itself to large volume application and subsequently we have chosen not to include it in our range of product or service offerings. If you have an application where you feel that Parylene may be required, there is a strong possibility that another Coating may suffice at far less expense.
- There are so many different Conformal Coatings available, how do I know which one is right for my particular application?
Selecting the best Coating for your application can be challenging. To assist you we have trained application engineers that will help identify the right process for you. We also suggest that your review the IPC´s CC-830 Conformal Coatings Handbook, available from the IPC at www.ipc.org
- What type of conformal coating should be used if the board has “press fit” connectors?
In this case, I would say that the key is to choose a soft coating to enable ease of push-fit and avoid risk of damaging the connector. Acrylic materials are generally used by most people doing this kind of assembly, although some softer urethane coatings can work with a bit more effort, especially if the connector is fitted as soon as the material is touch dry. UV cure materials are generally pretty tough after UV curing and so are less suitable (in general) for this kind of assembly.
- How thick should the conformal coatings be for optimum protections?
Traditional conformal coatings such as epoxy, polyurethane, acrylic and silicone recommend 50-75 micron thickness. Other than silicone, epoxy, acrylic and polyurethane conformal coating are generally hydrophilic and more susceptible to moisture penetration.
We use conformal coatings that are engineered to be super hydrophobic – such as the AIT CC7090-E and SC7130 are effective from 5-15 micron thickness. Thicker coating thickness is not necessary but will not have any negative effect.
When the conformal coatings are hydrophobic, the thickness requirements are not as important.
- Should I conformal coat the edges of the circuit boards?
Most circuit board edges are cut and thus are not protected with any coating. Whenever possible, the edges should be coated over with conformal coating to prevent easy moisture and water migration between the board solder mask and the board itself.