Designing Electronics for Harsh Conditions
February 12, 2018 | Patty Rasmussen, East West ManufacturingEstimated reading time: 5 minutes
This chart provides a visual of how IP ratings are applied and read. (Source: superbrightled.com)
What are Conformal Coatings?
Most electronics include printed circuit board assemblies (PCBA), fiberglass boards with components attached that are then sprayed or 'painted' with conformal coatings to keep the circuits dry and dust free. Conformal coating is an inexpensive way to keep electronic components functioning in less than ideal environments. There are five main types of conformal coatings, each with their advantages and disadvantages. The coating you choose is based on the application of your electronic product and the functionality requirements within the application.
Urethane Resin (UR)
Urethane resins can be either single- or double-part substances.
Advantages
- Great chemical resistance
- Good humidity resistance
- Resistant to mechanical wear
Disadvantages
- Difficult to remove
- Risk of peeling
- Long cure times common
- Use of soldering iron for rework could leave brown-colored tint
Acrylic Resin (AR)
Acrylic resins are preformed acrylic polymers that have been dissolved in a solvent (Source: ACI Technologies). They are typically one-part substances.
Advantages
- Easily applied and removed
- Makes for easy rework or repair
- No shrinkage during curing process
- Affordable option
Disadvantages
- Low chemical and solvent resistance
- Low abrasion resistance
- Not ideal for harsh environments
- Not ideal for high-temp applications
Epoxy Resin (ER)
Urethane coatings are usually two-part compounds, although one-part varieties are also available.
Advantages
- Great abrasion and moisture resistance
- Great chemical resistance
- Good humidity resistance
- Excellent performance in harsh environments
Disadvantages
- Difficult to remove
- Shrinkage during curing process
- Soldering iron required for rework or repair
Silicone Resin (SR)
Silicone resin coatings are single-component compounds that are often chosen for electronics that will be subjected to extreme temperature ranges.
Advantages
- Performs well in extreme temperatures
- Excellent humidity and corrosion resistance
- Good chemical resistance
- Adheres well to most PCB components/materials
Disadvantages
- Most difficult to remove
- Removal requires strong chemical strippers and harsh abrasion
- Localized repairs only
Parylene (XY)
Parylene coatings are applied through a process called chemical vapor deposition. Parylene becomes a gas when heated. After cooling, it is put into a vacuum chamber, where it polymerizes and turns into a film. The film is placed over the electronics.
Advantages
- Best solvent and extreme temperature resistance of all coatings
- High dielectric strength
- Coating forms at room temperature; no curing time required
- Transparent and colorless
Disadvantages
- Difficult to remove, must be abraded off
- Specialized equipment needed for chemical vapor deposition
- Not ideal for long-term exposure outdoors
Designing electronics to survive the abuse we humans can create is no easy task, but you're not on your own. Guidelines like IP ratings, MIL STD 810g and understanding the pros and cons of the various conformal coatings can help direct your engineering team as they work to create your ideal product—able to withstand whatever gets thrown at it.
This article originally appeared on the East West Manufacturing blog, which can be found here.
Page 2 of 2Suggested Items
AIM Solder’s Dillon Zhu to Present on Ultraminiature Soldering at SMTA China East
04/22/2024 | AIMAIM Solder, a leading global manufacturer of solder assembly materials for the electronics industry, is pleased to announce that Dillon Zhu will present on the topic: Ultraminiature Soldering: Techniques, Technologies, and Standards at SMTA China East. This event is being held at the Shanghai World Expo Exhibition & Convention Center from April 24-25.
Hentec/RPS Publishes an Essential Guide to Selective Soldering Processing Tech Paper
04/17/2024 | Hentec Industries/RPS AutomationHentec Industries/RPS Automation, a leading manufacturer of selective soldering, lead tinning and solderability test equipment, announces that it has published a technical paper describing the critical process parameters that need to be optimized to ensure optimal results and guarantee the utmost in end-product quality.
New Book on Low-temperature Soldering Now Available
04/17/2024 | I-Connect007I-Connect007 is pleased to announce that The Printed Circuit Assembler’s Guide to… Low-temperature Soldering, Vol. 2, by subject matter experts at MacDermid Alpha Electronics Solutions, is now available for download.
Nordson Electronics Solutions Expands the SELECT Synchro Selective Soldering Equipment Family With New Synchro 3 Release
04/03/2024 | BUSINESS WIRENordson Electronics Solutions, a global leader in reliable electronics manufacturing technologies, releases the Synchro™ 3, a new model in the SELECT® Synchro™ selective soldering equipment family for high-volume printed circuit board assembly applications.
Revolutionizing Precision Soldering: Introducing the iBot-i1/2s by Sasinno Americas
04/02/2024 | Sasinno AmericasSasinno Americas is pleased to introduce its latest advancement in soldering technology – the iBot-i1/2s. This cutting-edge system redefines precision soldering with groundbreaking features designed to elevate efficiency and performance in electronics manufacturing processes.