The interest in, awareness of and need for conformal coating has never been greater. With the continued drive towards miniaturisation, increased performance expectations among users and the ever more diverse and unexpected operating environments encountered, increasing the reliability of electronic assemblies becomes increasingly more of a challenge.
Conformal coatings have long been used in military and aerospace environments, and more recently have become more prevalent in automotive electronics as an additional level of protection to prevent corrosion and other failures due to humidity and condensation. Increasingly, however, industrial control electronics and even consumer devices require coating to survive their warranty period, and provide a consumer acceptable lifetime.
Increasingly, western designed electronics are being manufactured and sold in developing economies, and encountering operating environments for which they were not designed, with high levels of humidity and pollution, resulting in some fairly corrosive operating environments. Many OEM’s have encountered these kinds of issues, and often, the addition of a protective layer of conformal coating has been a more cost-effective solution than redesigning the device, electronics and or enclosures.
A Tale of Two Countries
One OEM of which we are aware had a monthly warranty claim in India alone of $600,000, for a mature, uncoated product design that had warranty claims in the region of $10,000 per year in North America. The company’s brand image was suffering and senior management was ‘deeply concerned with finding a solution’.
One year after instigating a conformal coating process, this OEM now has warranty claims of under $10,000 in India. The OEM achieved an ROI of greater than 60%, with a less than two month payback. The Senior Leadership team is delighted, the operations manager responsible for the implementation was promoted to a global corporate role and they are looking to implement coating on all new designs and adopting a ‘design for coating’ mantra, based on their experiences over the last year. All in all, a total success story?
Well not quite. It took them three months to identify and prove the root cause failure mechanism was corrosion due to the cocktail of sulfides and nitroxides, present in significant quantities in the polluted indian cities, mixing with humidity and condensing as acidic solutions on the electronics, in a similar fashion to the ‘acid rain’ phenomenon so familiar in the west.
After they had diagnosed the
failure mechanism, it took them two more months to decide on conformal coating, rather than changing the housing, gasketing the housing or potting as solutions. Then they decided to adopt the conformal coating used by their parent company on the basis ‘if it was tested and found good enough for them, it would be good enough for us’.
They then coated assemblies for test, by hand using an aerosol spray can, and ran them through a 3 month much shortened verification campaign, at the end of which all the units bar one had failed dismally. 2 weeks later they had a failure report which attributed most of the failures to either ‘the conformal coating material was not able to protect the circuit from the test environment’ or that ‘poor coverage and bad application technique were responsible for the failures’.
The engineering team gets smart
Thankfully, the failure analysis brought the operations team into the equation, since if the application method was important, then that should be considered as part of the solution. The operations team got the selective coating equipment suppliers involved, and a partnership with the conformal coating material supplier was formed.
The manufacturers of the materials and equipment provided some actionable input, and a new set of assemblies was coated with a robot and a different (much more expensive) material and subjected to the test regime.
Three months later all of the test units had survived the accelerated test, the material was fast-tracked through the corporate qualification program (another two months) since it was unknown and untested by them, and the implementation program began with another two month lead time on production equipment.
The real cost of implementation
The OEM had still been stuck with the warranty claims throughout the process development of nearly one year (approx $7,200,000)
Laboratory testing at an outsourced laboratory for the 6 months of actual validation, the expedited failure analysis report and the cost of corporate qualification cost the program close to $500,000
The overhead cost of the project team with an equivalent ten full-time members ran to nearly $1,000,000
The opportunity cost was unmeasured, but the same team were required to solve a soldering defect which was deferred.
The damage to the brand reputation of the additional year’s field failures and warranty returns.
The capital equipment for five production lines ran to $600,000
The material expenditure ran at $300,000 per annum
Total Investment = $9,300,000
Payback = 31 Months
3 Yr Return = 1%
5 Yr Return = 4%
Of course, the big number here is the length of time during which they continued to field warranty claims (and pay the project team, and an extra set of lab tests and more delay due to the false start with the original material and application method). The selection of which was based on a bad assumption, and could very well be made again. Was it the material or was it the application method that caused the failures in the first round of testing? Is there a way to separate the two? Does this dilemma sound familiar?
Is there a better way?
Conformal Coating is a process, not a material. Not all materials and processes are created equally. When it comes to increasing the reliability of your printed circuit assemblies in harsh operating conditions, you need to know which conformal coating materials and application processes provide the best levels of protection for your assembly.
• Whether your material is the best available or most suitable for your application
• Whether your
conformal coating application process is giving you the best results from your material
• Whether there is a significant difference in protection provided by the various application methods.
• Which materials and processes you should be considering for your new (or legacy) projects.
Had the OEM team been armed with this report, they would have known that the initial
conformal coating material selection and application method was or was not suitable and could have saved half of the time (and $4,500,000) they spent on this project, reducing the payback by seven months to 24 months, improving returns to a more respectable 5% and 9%, reducing the damage to their brand reputation and moved onto solving the solder defect quicker, thus compounding their savings.
