Enhanced protection for enhanced PCB performance
Conformal coatings are designed to protect printed circuit boards and related equipment from their environment. Typically applied at 25-75μm, these coatings ‘conform’ to the contours of the board allowing for excellent protection and coverage, ultimately extending the working life of the PCB.More info > Download product selector chart > Download product brochure >
The use of conformal coatings is particularly important in automotive, military, aerospace, marine, lighting, industrial and green energy applications. Due to the rapid expansion of the electronics industry, conformal coatings are also finding their way into the domestic and mobile electronics industries, providing the necessary combination of high performance and reliability within a vast array of electronic devices.
Conformal coatings can be used in a wide range of environments to protect printed circuit boards from moisture, salt spray, chemicals and temperature extremes in order to prevent corrosion, mould growth and electrical failures, for example. The protection provided by conformal coatings allows for higher power and closer track spacing, in turn enabling designers to meet the demands of miniaturisation and reliability.
Electrolube is among the world’s 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, hybrid chemistries and environmentally friendly options.
Electrolube can offer both transparent and pigmented coatings to improve or camouflage the appearance of printed circuit boards. The range also includes a number of ancillary products to complement the use of our conformal coatings, including thinners and removers, peelable coating masks and thixotropic materials for dam and fill applications.
Conformal coating standards are a series of specifications and tests which a coating must pass in order to be considered for use in certain environments such as Military or Automotive applications.
Most conformal coatings are either qualified to MIL-I-46058C or meet the requirements of the closely related IPC-CC-830B specification. In addition they may be recognised by Underwriters Laboratories, either as a permanent coating, in which case the flammability of the coating is assessed to UL94V0, or as a conformal coating, where the electrical properties will be assessed as part of the UL746E standard.
These tests all require flat coupons to be coated with the conformal coating in question and are subjected to a variety of temperature and humidity conditions to assess the material’s properties. Whilst perfectly acceptable to assess the potential performance of the material, the actual protective capability of the coating in the end use environment is of greater concern to the user. The rest of this article will be devoted to understanding the issues that relate to end use performance in potentially corrosive environments.
Military Insulating Compound – this is a common standard used throughout the industry for conformal coating materials. While it has been inactive for new designs since 1998, it is still a standard often required by military contractors. The main advantage of MIL-I-46058C is that it requires independent testing by a MIL approved laboratory (although at least one conformal coating manufacturer is an approved test laboratory so not completely independent!) and the military maintains a Qualified Product List (QPL) drawn from successful independent test reports.
The UK Ministry of Defence standard – similar to the MIL-I-46058C this is a standard used by the British military for coatings used in high end electronics.
International Electrotechnical Commission. Whilst similar in requirements to MIL-I-46058C, this standard is based on supplier self-certification. Of course, an independent test laboratory can be used, but the IEC does not maintain a QPL.
IPC-CC-830B is closely related to MIL-I-46058C and was introduced to provide an alternative to the MIL spec when it was declared inactive. CC-830 is an active specification and is continually being updated. Once again, there is no requirement to use an independent test laboratory, and there is no QPL maintained for this specification. Materials qualified to MIL-I-46058C are automatically deemed to meet the requirements of IPC-CC-830B.
UL94 relates to the flammability or self-extinguishing nature of the conformal coating on an FR4 substrate. V-0 is the highest classification that can be achieved, with other categories such as V-1 and V-2 denoting materials that burn for longer durations.
UL746E is composed of a series of dielectric breakdown evaluations in addition to the UL94 flammability testing, and is intended to denote products that can be safely used on products that are required to meet UL safety standards. By documenting the use of UL recognised materials throughout the design, manufacturers can avoid the requirement to test their device to the applicable UL safety standards.
Here at Electrolube we believe that it is everyone’s responsibility, both individually, and as a business look after the world in which we all inhabit. Our R&D team are always looking at ways to minimise our environmental impact and we have several groundbreaking products as a result.
Policy:- Environmental Policy
‘Volatile Organic Compounds (VOC) means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates and ammonium carbonate, which participates in atmospheric photochemical reactions.’
‘Any organic compound with a boiling point less than or equal to 250˚C at a standard pressure of 101.3 kPa.’
Previously the directive referred to the definition as ‘Any organic compound, having at 20˚C a vapour pressure of 0.01KPa or more, or having corresponding volatility under the particular conditions of use’.
As stated on the European Commission website, either method is suitable:
‘The “boiling point approach” was adopted for Directive 2004/42/CE because during negotiations Member States were generally more in favour of this definition of VOCs than the “vapour pressure approach” definition in Directive 1999/13/EC. The main reason is that the boiling point of a substance is easier to identify (and presumably more data are available) than the vapour pressure at room temperature of the same substance. Nevertheless, the results of the two approaches for any one substance are, to the knowledge of the EU Commission, in most cases identical.’
Products such as the Electrolube water-based coatings help to keep VOC levels to an absolute minimum without compromising on performance:
Electrolube are continually developing ‘greener’ technologies, helping to minimise solvent emissions and their impact on the environment.
Registration, Evaluation and Authorisation of Chemicals – the REACH system
If you have any questions about any of the above, or need some help or advice, please give us a call or Contact us