Blog

This blog post outlines the techniques required for the removal of HumiSeal UV cure conformal coating. The products covered in this article are:

• UV40, UV40-250
• UV50LV
• UV500, UV500LV

Before we look at conformal coating in the 21st Century, it is worth looking at how our industry has changed since the 20th Century and the effect these changes have had on reliability. 

30 years ago, we had:

• Through-hole PCAs with axial components and wide conductor spacing (see fig. 1)
• Round axial components that were easy to conformably coat
• Wide conductor spacing (causing a few problems with dendritic growth)
• Leaded solder
• The widely adopted practice of cleaning before conformal coating

Fig. 1

Now move forward 30 years. In that time, surface mount components have been developed that are predominantly square with sharp edges, conductor spacing has been reduced, and packing densities have increased to levels never dreamt of in the past (see fig. 2). 

When conventional coating methods such as hand spray, total dipping or robotic selective coating don’t provide the protection required, there is always selective dip coating.

What is selective dip conformal coating?

Selective dip coating is a process whereby the substrate rather than globally immerised in the coating, is discreetly coated in desired locales.  The technique in one form or another, has been around for over 25 years and is used with both classic solvent-based coatings and 100% UV cure conformal coatings.

Counterfeit conformal coatings have infiltrated the electronics industry, posing a significant threat to device reliability. These counterfeit coatings may look like genuine products, but they lack the quality and protective properties required for electronic applications. Here are some reasons why counterfeit conformal coatings are causing failures:

Conformal coatings have a long and storied history with printed circuit boards. A good conformal coating protects PCB components from moisture, corrosion, contaminants, and additional PCB threats like vibration and thermal shock. Coatings are a complicated science, and there isn’t one best coating or application method for every job. These choices are dependent on the design, use case, and assembly of the PCB. For instance, manual brushing PCB coating material is a slow, tedious process; but for small batch applications, it’s quite cost-effective.

Regardless of the chosen method, there are fundamental application errors that can occur, leading to defects forming in the coating which ultimately limit the functional service life of the PCB.

Conformal coating technology is on a continuous path of improvement, and we're excited to say the latest step on that path just happened. UV550 is the most recent innovation from HumiSeal, continuing the trend of industry-defining capabilities in the conformal coating space. This is to be expected from the original inventors of conformal coating material. But what sets UV550 apart from the rest?

Let's discuss how the ever-changing requirements of the automotive and white market space fueled the thresholds this uv-curable material attains, especially with regard to its durability under the most extreme thermal and mechanical cycling conditions.  

We at HumiSeal are no strangers to conformal coatings; and if you’re reading our blogs, it’s likely you’re familiar with these coatings as well. The word “conformal” is descriptive of the function of the coatings which are expected to spread and conform evenly across all surfaces that are to be protected. This uniform and even distribution is necessary to protect delicate electronic components from things such as humidity, water, vibrations, and thermal damage (to name a few).

Manual brushing is just one of many methods commonly used for applying conformal coating materials to PCBs and other components. It is a hand-applied method that requires little investment into automation or equipment. With practice, it can be one of the simplest methods available, especially for small-batch production or isolated applications.

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.