• UL and MIL approved
• Solvent removable and solvent resistant coatings
• Acrylic, silicone, polyurethane and solvent free
• UV trace to aid inspection
• Thinners and masking products

Conformal coatings are specially formulated lacquers designed to protect PCBs and related equipment from their environment. This improves and extends their working life and ensures security and reliability of performance. These coatings ‘conform’ to the contours of the board and its components creating a thin (25 – 50µm) layer which is both lightweight and flexible. They protect circuitry from hazards such as chemicals (e.g. fuels, coolants etc.), vibration, moisture, salt spray, humidity and extremes of temperature this can prevent corrosion, mould growth and current leakage which may otherwise result in board failure with an un-coated PCB.

Electrolube is among the worlds foremost experts in the formulation and application of conformal coatings designed to meet international approvals (including European and American military specifications). The range of products currently available comprises acrylics, silicones, polyurethanes and water based coatings. Electrolube can offer products with UL approval and most utilise a UV trace to aid inspection. (DCA SCC3)

Electrolube also offers a full range of ancillary products to complement the use of our conformal coatings that include thinners and strippers, peelable coating mask and thixotropic materials for the effective coating of lead ends. (FSC, PCM, NSC)

Benefits of Conformal Coatings

Conformal Coatings application chart

These coatings improve the reliability of PCBs, enhance security and ensure life-long performance by forming a protective layer which insulates and protects circuitry against the effects of environmental attack from chemicals, moisture and other contaminants.

Conformal coatings allow higher power and closer track spacing as they prevent current leakage. This, in turn, enables designers to meet the demand for miniaturisation.

Both transparent and pigmented coatings improve the appearance of PCBs - the latter ensures a high degree of security by camouflaging the components and layout.

Typical Applications

Initially conformal coatings were only used in ‘high tech’ applications. As consumers become more concerned with quality and reliability, and electronic assemblies become more widely used in everyday life, conformal coatings offer manufacturers the ability to improve the quality of their products whilst eliminating costly warranty failures.

Typical areas of use include domestic and commercial electronics, automotive, aerospace, marine, medical and industrial.

Selection Criteria
With such a wide range of conformal coatings, all offering differing features and benefits, it is important that the correct coating and method of application is chosen. The main questions to be addressed are:-

• Working environment
• Electrical requirement
• Board layout
• Method of application
• Rework and repair

Working Environment
Controlling or predicting the exact operating conditions is difficult to achieve without expensive, sophisticated test chambers, so the solution is to protect the circuit completely from the hazards it may face.

The physical demands on equipment range from sudden decompression, as an aircraft climbs through the atmosphere, to the constant vibration of an office printer; so flexibility and the ability to expand and contract are important features in a conformal coating. Checks should be made to ensure these characteristics are maintained when sudden pressure and temperature changes take place, and that the material will retain these properties throughout the lifetime of the equipment.

Electrical Requirements
A conformal coating should exhibit high dielectric strength and breakdown voltage. The minimum required dielectric strength of the coating can be determined from the inter-track separation and the potential difference between adjacent tracks.

Board Layout
The design of the board should include consideration of the placement of components that must not be coated. These components include connectors, IC sockets, adjustable potentiometers and test points. If the design allows, these components should be placed on the edge of the PCB to enable the board to be coated with the minimum of masking. If this is not possible, Electrolube provide a fast curing peelable coating mask to protect the relevant components. Component legs should be cropped to minimum length to ensure a coherent film is formed.

Rework and Repair
If the assembly requires repair, consideration must be given to the ease of removal of the coating. Most coatings may be safely soldered through and some can be easily removed in a standard solvent.

Electrolube can also supply powerful solvents and strippers to remove the most stubborn, aged coatings.