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Take a quick look at the photograph on your right. If you are in the business of PCB manufacturing with conformal coatings, does it frighten or concern you at all? Does the magnified coating appear to truly “conform” to the surfaces evenly? And if not, what effect, if any, might this have on the protection of your PCBs?

First of all, don’t panic. What you see in the photograph is not unusual and is not necessarily a problem. It is important, however, that if you are in the business of applying conformal coatings, you should have a clear understanding of some of the unique challenges they present.

UV curable conformal coatings have attained widespread use in applications requiring fast through-put times, such as automotive, white goods, and industrial control manufacturing. In addition to speed of cure, UV curable conformal coatings provide the advantage of high physical protection and chemical resistance for electronic systems. Traditionally the UV curing of coatings is an energy intensive process. One that uses high-power mercury discharge lamps, which as a result of use produce considerable amounts of heat and ozone. The recent introduction of new, high-output LED UVA light units allows for the successful cure of conformal coatings by using between 365nm and 395nm wavelength of UVA light, effectively curing with minimal heat and no ozone generation.

Adoption of plug in -electric vehicles (EVs) has been slower than many expected, but there is little question the next few years will see adoption accelerate. Your hypersensitive dog will have to find new visitors to harass when your delivery drivers arrive without notice, driving to your door silently in all-electric commercial vans. Many of your favorite suppliers and stores have already ordered these vehicles. Game-changing battery and charging developments are eliminating range anxiety, and autonomous driving controls and safety innovations are in the final stages of building our trust.

Modern hydrogen fuel cell technologies require ever more sophisticated and reliable electronic control systems to assure both safety and longevity. Hydrogen fuel cells are gaining in popularity in critical industries including automotive, aerospace, ocean transportation, military, and power microgrid systems among others. Protection of printed circuit boards and their components from physical, chemical, and thermal damage is essential to produce robust and reliable fuel cell systems for demanding applications.

One of the most basic and common questions we at HumiSeal^® are asked by both existing and potential new customers is,

“How much does it cost to conformally coat my printed circuit boards?”

Since conformal coatings are usually sold in liquid form by the liter or gallon, it is necessary to go through a fairly basic calculation that we will present here.

The simplest and most common way to evaluate cost is by determining the cost in dollars of coating per PCB.

A critical function of conformal coatings is to protect PCBs and electronics from damage caused by moisture and humidity. In this discussion, we will attempt to answer some of the more common questions we often hear regarding the level of protection you can expect from a conformal coating.

Are conformal coatings waterproof?

The above is probably the most common question and most misunderstood subject in the area of PCB protection

In previous articles, we discussed common defects in conformal coatings related to surface energy issues. These included issues such as

• fish eyes
• lack of coating coverage
• poor bonding
• delamination

We received significant feedback, and the most common response was to ask for more specifics about just what surface energy is anyway.

The PCB industry continues to evolve with ever increasing demands for efficiency and manufacturing cost reductions. From the design phase onward, suppliers and contract manufacturers are being asked by their OEM overlords for increased performance at lower and lower costs. An obvious potential source for cost reduction is the use of alternative cheaper raw materials or their elimination where possible. At some point in the discussion, it is sometimes asked,  “Why don’t we just eliminate the conformal coating?” or "Are conformal coatings necessary".

Conformal coating of printed circuit boards (PCBs) has resulted in a steady evolution in performance and protection for modern electronics. It has allowed for lightweight and reliable controls in industries such as automotive and aerospace among others. This has brought about the possibility of increased length of warranties as well as fewer failures and claims. Nevertheless, original equipment manufacturers (OEMs) and consumers continue to raise their standards and expectations for longevity and reliability to levels unimagined just 10 years ago. In the automotive industry, as an example, thermal cycling testing might have involved as few as 10 or 50 cycles in the recent past. That standard is now often 500 or even 1000 cycles with no apparent ending in sight.

So what do I do when conformal coating is not enough?

Nobody likes masking, nevertheless it can be a necessary part of your PCB production process.

“But I thought selective conformal coating equipment had eliminated the need for masking in most cases.”

The cost of selective conformal coating equipment can easily run into hundreds of thousands of dollars. Even those who invest in the latest selective coating technology find, at times, that masking in certain areas is the only solution.