HumiSeal® UV20Gel: Durability and Reliability for PCBs Under Thermal Stress

Posted by Chase Corp Editor on May 10, 2022 11:16:46 AM
Chase Corp Editor
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UV20-Thermal-Stress-blog HumiSeal UV20Gel is a unique, strong, and flexible gel coating developed to protect PCB (Printed Circuit Boards) components against environmental conditions and vibrations. UV20Gel has proven successful in many demanding industries and product families including-

  • Conventional Automotive
  • EV and Industrial EVs
  • White Goods such as Washers, Dryers…
  • Agricultural Vehicles and Machinery
  • And many more

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Over the past few years, HumiSeal scientists have been developing an extensive base of knowledge regarding UV20Gel that can be valuable for PCB design engineers' considerations. One such area is high-temperature (thermal) aging and stability.

Related Article: UV20Gel - Shock and Vibration Testing


What is Thermal Stress and Why Thermal Stability Matters

PCBs have become ubiquitous, not just in automobiles but across products and industries where such things were unimaginable in the past. Consumers have shown a preference, and a willingness to pay, for “smart” technology in products, including outdoor grills, washers and dryers, handheld devices and tools, toasters, and even clothing.

PCBs and their components are expected to hold up to extensive vibration over long time periods in many of these situations. In addition, control of temperature and humidity is impossible on something like an outdoor smart grill or a wearable device for a marathon road race.

Humiseal UV20Gel has undergone extensive testing for temperature and humidity conditions common to many of these demanding applications.


Dry and Wet Thermal Stress Testing

The following is a brief discussion of some of the testing that has been conducted in-house regarding temperature and humidity stability of the protective properties of UV20Gel with PCB components.

Related Article: The Evolution of UV Curable Conformal Coatings


400 Hours at 125 C “Dry” Bake

Test Description:

Test samples were created in accordance with ASTM D412 “dumbbell samples” and the tensile testing was conducted in a manner like the ASTM D412 method but without a climate-controlled oven. Critical sample size measurements are taken from the thin middle part of the dumbbell which is where the force is applied. These measurement targets are 1.5’’ x 0.24’’ x 0.06’’ however each sample is measured separately with digital calipers and the actual measurements are used to calculate % elongation and tensile strength in psi. The speed of separation was also changed to accommodate the tensile elongation at break. After testing materials at 100, 200, and 400 hours it was found that the material retained original tensile strength and elongation values within the seen error of the test.

UV 1


2000 Hours at 85 C/85% RH “Wet” Bake

The test was conducted internally. It involved creating mechanical strength samples of UV20GEL in the same method as the above listed “Test #1 – 125° C dry bake.” After the samples were created, they were tested for an initial value (t = 0) and then placed inside a humidity chamber oven on top of aluminum foil with an oven temperature of 85° C ± 0.5° C and relative humidity of 85% ± 1%. After 2000 hours the samples were removed, allowed to come to room temperature for 2-3 days and tested for tensile strength and tensile elongation at break. Samples were also periodically removed and tested throughout the duration of the test to track any changes during testing. UV20GEL maintained tensile strength and elongation within test error throughout the duration of the 2000-hour test.

UV 2


Humiseal UV20Gel has been successful in protecting PCB components from vibration and environmental conditions when traditional conformal coatings alone are not up to the task. This protection depends on the polymer maintaining tensile and elongation strength and flexibility characteristics over time. Humiseal scientists have recognized the need for data regarding performance over time and under temperature and humidity conditions typical to many of these industries. As can be identified in the data and testing within this presentation, Humiseal UV20Gel has shown consistent tensile and elongation properties when tested at continuous operating temperatures as high as 125 C for 400 hours and combined conditions of 85 C and 85% RH for up to 2000 hours.

Related Article: How Best to Protect PCB from Vibrations


As a supplier of most forms and chemistries of electronics and industrial coatings, Chase and Humiseal can help you with an unbiased approach to evaluating your application and process. We’ll show you how to maximize efficiency, minimize cost, and improve product reliability. Our outstanding manufacturing and technical support groups can provide your organization with reliable global supply, unmatched quality, and superior technical support.

Please contact us today to discuss your application!

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Topics: Electronic Protection, Vibration Suppression, Thermal Compatibility, Protection for PCB, Thermal Stress Testing

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