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How do you select and test a conformal coating that is right for your specific application? Or maybe you would like to create your own test specification due to any special characteristics of your device’s operating environment? Or depending on your geographical location, you may also be required to use a different testing specification that is dictated by local authorities.

A widely used method to create an internal specification, is to simply select a conformal coating material that meets an existing specification standard. Such standard could be MIL-I-46058C or IEC-60664. However, you must be careful to ensure that the existing standard that you choose, does indeed meet 100% of your requirements. In such cases, you may have to specify test methods from other existing standards.

So, you’ve spent a considerable amount of time setting up your conformal coating process only to observe the dreaded cobwebbing effect once you start applying the material. Well, in this blog post, I’m going to run through the common root causes and provide some simple solutions you can take to get you back to applying your coating in a defect free manner.

The counterfeit of electronic materials is nothing new in the industry. There are numerous sources of these fraudulent practices and they come in various forms. However, the most important aspect is the cost that these forged coatings have on users.

It is known and well documented that in today’s electronics industry, there are some PCB board components that may come from manufacturer scraps, re-labeled unused parts, and removed components from used circuit boards. It has been reported that most of these electronic components are integrated circuits. 

Dear customer, thank you for many years of patronage and for your continuous support to HumiSeal conformal coating products. To celebrate you, the customer, we would like to share some findings of our internal survey. The objective was to find the characteristics of our ideal customer, those whom we have had the most success. 

Have you ever wondered if your UV oven is performing up to specification?   Has your UV curable conformal coating come out of the oven tacky?  Today I’d like to take a few minutes to write about the importance of calibrating your UV oven to ensure you are getting the most out of our UV conformal coatings.  Setting up and optimizing your UV oven is a simple process that can be accomplished in three easy steps.  Here’s what you’ll need to get yourself started!

• Conformal coating technical data sheet (TDS)
• UV radiometer (calibrated and certified)
   

That’s it!  You only need these two items to successfully test and optimize your UV oven whether you are using a benchtop or inline UV curing system.  

Hello Again!  The last time we discussed bubbles in conformal coating, I wrote how to resolve process related root causes.  There are other simple ways to reduce the amount of bubbles:

• by varying the types of solvents used in a product
• by using a product that contains a surface tension modifier, hence increasing the rate at which bubbles burst.

If you recall, most of the bubbles are basically solvent or air entrapped in the coating.  As you might expect, the air and solvent try to find their way up through the liquid to escape.  The problem is that the surface dries first, creating a thin skin that prevents those bubbles from escaping.  Therefore, the solution is to eliminate the bubbles in the coating prior to the skin formation.   In other words, use a solvent set and other surface tension reducing chemistries to accelerate elimination of bubbles.

Figure 1: Thermally induced cracking in conformal coating

Does your conformal coating require long term thermal shock testing?   Do you struggle to overcome cracking and adhesion loss with your current conformal coating after 1000 thermal shock cycles?   With the drive for increasing functionality for end devices, and increased life cycles being placed on all electronic assemblies, the need to have materials endure more stringent testing becomes increasingly vital.  Necessary robustness to these stringent conditions force suppliers like HumiSeal to innovate new material solutions to address these requirements.

What is so special about synthetic rubber conformal coatings?   Why do many high reliability applications require synthetic rubber?  Would synthetic rubber be a better fit for your application?  Synthetic rubber copolymer provides higher operating temperature and exhibits superior mechanical properties compared to traditional materials. The products have been developed to withstand the demanding conditions in the most severe environments required in today’s applications.  Commonly used conformal coatings are acrylic, polyurethane and silicone.   Less known are synthetic rubber conformal coatings, however these have been used for many years and HumiSeal continues to develop new and improved varieties of this chemistry.

Have you ever experienced uncontrolled conformal coating migration?   Have you had to strip your recently coated boards because conformal coating wicked into non-desired keep out zones?   Wicking is a phenomenon caused by a combination of low surface tension coating, which is usually characterized by low viscosity, coupled with strong capillary forces generated by low standoff gaps possessed by the SMT process.   Wicking into connectors; onto grounding hole; or under sensitive components will create defects that will have to be reworked, as it may cause reliability concerns with the finished product, which we will describe in detail.   There are ways to either reduce and/or eliminate wicking issues through decisions made during preparation, application, and conformal coating selection.