Conformal Coating for automotive electronics applications »Reliability in the automotive industry perhaps higher even than aerospace«

Phil Kinner, Electrolube: »Auf Grund der ’aus weniger mehr herausholen‘-Philosophie unserer Gesellschaft erwarte ich, dass der Bedarf an Lackierprozessen mit höherer Leistungsrate, mit kürzeren Durchlaufzeiten, höherer Fertigungsgeschwindigkeit und einem höheren Maß an Automatisierung ganz alltäglich werden wird.«
Phil Kinner, Electrolube: »The unique reliability challenges provided by automotive electronics will continue to drive the development of new chemistries and new processes to provide ruggedisation to the electronics systems. Conformal coating will continue to be a key part of that ruggedisation tool kit, although perhaps not in exactly the same form as we are used to.«

Balancing the requirements of environmental acceptability, manufacturing acceptability and end-product reliability continues to be the main challenge facing coating formulators especially in the automotive electronics industry. Electrolube's new range of conformal coatings can help users address all of these issues simultaneously. We talked to Phil Kinner, Head of Conformal Coatings at Electrolube.

Markt&Technik: Over the past decade, the automotive electronics industry has evolved significantly, what changes have you seen?

Phil Kinner: The automotive electronics industry has evolved rapidly during the last decade. The most striking aspect is the way that the use of electronic controls, sensors, safety features and in-cabin entertainment, communications and navigation, have been adopted in mid and low-end vehicles. Automobiles are now much safer, more fuel-efficient and more comfortable as a direct result of the increased adoption of electronics.

On top of this, we have seen the emergence of electric vehicles offering a more environmentally acceptable alternative to fossil-fuel based vehicles. These electric vehicles now have a range that is useful to most commuters (150-200km) and we are seeing a rapid installation of charging stations and other infrastructure requirements to make these vehicles more mainstream. Finally, we’ve seen the emergence of smart cars that can communicate with each other, making pre-emptive interventions to help maintain safety and avoid collisions, with ‘driverless’ vehicles making daily journeys on highways and other roads without major incident. Who would have thought that would be close to a practical possibility a decade ago?  

The industry faces many challenges to manufacture reliable electronics that meet the many automotive regulatory requirements. How does Electrolube help automotive electronics customers accomplish this?

I would say that the challenges on electronics reliability in the automotive industry are perhaps higher even than aerospace applications, due to the fact that aerospace systems usually have at least 2 back-up systems that automotive systems do not. The elimination of cleaning from many automotive electronics assembly processes has placed an even greater emphasis on the performance requirements of the protective coatings.

Given the volume of automotive parts produced, the use of solvent-containing products is discouraged to help meet solvent-emissions targets. The list of prohibited substances for use in automotive applications continues to grow. The manufacturing processes need to be ‘lean’ and provide ‘one piece flow’ at the maximum possible, defect-free, manufacturing velocity. As an ISO14000 company itself, Electrolube is dedicated to producing products that can help automotive manufacturers achieve all these requirements, whether it is the demonstrably higher performance solvent-free conformal coatings, encapsulation resins for more demanding applications, high performance lubricants and greases for enhancing switches, bearings and other moving parts or advanced thermal management for keeping assemblies cool to extend their lifetimes, Electrolube has a great portfolio of products to help enhance the reliability and productivity of automotive electronics.  

What challenges do you face as a manufacturer of conformal coatings with your automotive electronics customers?

We see our customers needing to achieve ever higher operating temperatures as the electronics continue to become more powerful resulting in higher temperatures, also, historically electronics have been considered in-cabin or under-hood, with greater requirements for under-hood applications. We are seeing a blurring within these boundaries and a drive towards using one material in both applications to simplify manufacturing processes.

From a performance point of view, thermal shock, the rapid transition from extremely cold, towards maximum operating temperatures, originally intended as a destructive test methodology has become an important acceptance criteria for customers, with the number of cycles increasing from 1000 towards 2000. This poses real challenges for some solvent-free chemistries, especially UV curable materials, so popular because of their manufacturing attractiveness from a ‘lean’ and ‘one piece flow’ point of view.  

What types of conformal coatings are best suited to automotive electronics and what do automotive electronics manufacturers need to consider to select the appropriate conformal coating for their applications?

There are many types of conformal coating that may be suitable for automotive electronics from Acrylics, Urethanes and Silicones that have been used historically, through to modern UV curable hybrids and even ‘ultra-thin’ coatings. The correct choice will always be dictated by a combination of performance requirements, manufacturing requirements and environmental considerations.

From a performance requirement point of view, the manufacturer must consider the end operating environment and determine likely minimum and maximum operating temperatures, consider the likelihood of splash or immersion in water or liquid spills, humidity/condensation and chemical exposures e.g. salt-spray, corrosive gases or unintentional oil spills etc. From an environmental point of view, the use of solvents needs to be considered, along with other chemicals that may be banned by company policy or international regulations such as RoHS, REACH etc. Finally, the manufacturer must give consideration to the possible coating application methods that may be used to manufacture the assembly and assess likely impacts on manufacturing throughputs, floor space requirements, Work In Process (WIP) and manufacturing velocity. They must also ensure that their application process and material selection work together to give an acceptably defect free process that meets their end reliability requirements. Considering these 3 key areas together, a manufacturer may find that a material that performs well in all 3 consideration factors, may be more suitable for their purposes than a material that has excellent environmental characteristics, but does not suit their manufacturing processes.