Conformal Coatings

Acrylic, Polyurethane, Silicone, UV and Rubber-Based Conformal Coatings

thin protective film to safeguard electronic assemblies

Epoxy Binding Resins Epoxy Coating Powders Conformal Coatings

Conformal Coatings

A conformal coating is a thin protective film designed to safeguard electronic assemblies from corrosion and environmental hazards in harsh operating conditions. The term "conformal" refers to its ability to conform precisely to the complex contours of the surface it covers. This coating offers several advantages, including protection from debris and dust infiltration, enhancing corrosion resistance, extending product warranties, and increasing overall reliability and safety. In essence, applying a conformal coating effectively prolongs the longevity and durability of electronic assemblies.

One of the main advantages of conformal coatings is their dielectric properties. These coatings exhibit excellent insulation resistance, effectively protecting electronic components and assemblies from electrical failures. Another significant advantage is moisture resistance, which serves as a crucial defense against moisture ingress, preventing potential damage and electrical failures in humid or damp environments. Additionally, the breakdown voltage characteristic plays a pivotal role in protecting the component from high voltages and electrical stresses. Finally, the flexibility of the coating endows the substrate with enhanced mechanical resilience, enabling it to better withstand external stresses and environmental fluctuations without deforming, cracking, or delaminating.

Overview

FAQs

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LINQCOAT PC-1032 | Acrylic conformal coating
- Acrylic Conformal Coating
- Transparent
- Dielectric Strength 30 kV/mm
4 - 6 weeks
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LINQCOAT PC-3112 | Fluorinated conformal coating
- Electronic component protection
- Quick dry time (3-5s)
- 0.1-1 micron coating thickness
8 - 12 weeks
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LOCTITE STYCAST CC 8555
- UV curable
- Excellent chemical resistance
- Good wettability and void free
8 - 12 weeks
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LinqSil LSC100 One-Part Liquid Silicone Semiconductor Junction Coating
- One-part liquid silicone coating
- For protection and passivation of semiconductor junctions
- Ionic purity levels of max 1 ppm
4 - 6 weeks
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LOCTITE SI 5293
- PCB/Electronics Protection
- UV and moisture cure
- Alkoxy Silicone
8 - 12 weeks
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LOCTITE STYCAST PC18M
- Conformal Coating
- For environmental and moisture protection
- Room temperature cure
8 - 12 weeks
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LOCTITE STYCAST PC40-UMF
- VOC free
- Single component
- UV and Moisture cure
8 - 12 weeks
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LOCTITE STYCAST PC62
- Fluorescent under UV
- Toluene free
- Easily removable with soldering iron
8 - 12 weeks

Henkel Conformal Coatings

	Loctite Stycast PC 62	Loctite Stycast PC 18M	Loctite SI 5293	Loctite Stycast 40-UMF
Film Thickness (µm)	25-200	Varies	Varies	Varies
Insulation Resistance, ohms: (50µm film, 25ºC / 50% RH)	>2.3×10¹⁴	>1×10¹⁵	N/A	N/A
Volume Resistivity, (ohms-cm)	1.04×10¹⁶	2×10¹³	1×10¹⁴	3.5×10¹⁶
Dielectric Strength, (volts/mil)	2,000	1200	406	420
Dielectric Constant / Dissipation Factor @ 100 KHz	2.29 / 0.12	4.2	4.6 / 0.005	2.75 / 0.12 @ 1 mHz
TYPICAL ENVIRONMENTAL RESISTANCE	Fungus Resistance per ASTM G21- Non nutrient	Fungus Resistance per ASTM G21-Non nutrient	N/A	NASA Outgassing: TML, % 0.87 CVCM, % <0.01 WVR, % 0.36
TYPE OF COATING	Acrylic	Polyurethane	Silicone	UV-Based

Frequently Asked Questions about Conformal coatings

How is a conformal coating applied?

There are multiple ways to apply a conformal coating, all based on the specifics of the application. Some methods include:

Hand Brushing
Hand Dispensing
Spray Coating - Aerosol/Handspray
Dip Coating
Selective Coating

How does conformal coating work?

The liquid coating "conforms" to any varied profile of an electronic component, completely covering all parts of the assembly to protect it from environmental factors.

Different types of conformal coatings

Acrylic - Acrylic-based coatings represent the largest market share of conformal coatings. These coatings are formulated from single components and provide superior moisture resistance properties, making them highly suitable for protecting electronic assemblies in challenging environments. The widespread choice of acrylic-based coatings can be attributed to their ease of use, short cure time, and reworkability/repairability. Acrylic-based coatings are most often used in Engine Control Units (ECUs), Avionics, and communication equipment.

Polyurethane - Polyurethane-based coatings have excellent chemical resistance, rendering them highly effective in countering the effects of compounds such as salt spray and noxious gas. Available in both one-part and two-part systems, these coatings are easy to apply. Compared to other conformal coatings, polyurethane-based coatings do have a lengthier curing time. Reworkability is a notable advantage of these coatings, and they are commonly used in demanding environments with applications that include industrial controls, marine electronics, and chemical processes.

Silicone - Silicone-based conformal coatings are uniquely characterized by their exceptional high-temperature performance. Due to this characteristic, they are suitable for industrial mining equipment, electronics with temperatures greater than 150°C, and underhood components in the automotive industry. Silicone-based conformal coatings offer reasonable moisture protection while remaining reworkable and repairable. They are solvent-free, yielding a 100% solid content and good solvent resistance. Moreover, these coatings incorporate flexible elastomers, enhancing their flexibility. This adaptability allows the coating to accommodate mechanical stresses and temperature fluctuations without compromising its integrity.

UV-Based - UV-Based conformal coatings are primarily selected for their short cure time, which occurs within a matter of seconds. This expedited curing process reduces the cycle time while providing increased temperature performance to the coated components. UV Based coatings exhibit excellent resistance to moisture and chemicals while also having high flexibility and abrasion resistance. One of the main advantages of this type of coating is that it is environmentally friendly, as it contains no Volatile Organic Compounds (VOCs) or solvents. Like Silicone Coatings, it is 100% solid content. Due to the short cure time, UV Based conformal coatings are suitable for high-volume applications.

Rubber-Based - Ruber-based conformal coatings represent a class of single-component coatings with excellent moisture resistance and low Moisture Vapor Permeability (MVP). Like other conformal coatings, they are easy to repair/rework, have a short cure time, and have excellent adhesion to various substrates. The characteristic that distinguishes rubber-based coatings is their superb flexibility and thermal-mechanical properties. Specifically, their low Coefficient of Thermal Expansion (CTE) and Glass Transition Temperature (Tg) enables the components to effectively withstand thermal shock, enhancing overall performance and reliability. This quality makes rubber-based coatings particularly well-suited for applications where temperature fluctuations pose a challenge, preserving functionality and integrity even in demanding environments.

How to select the right coating for your application
	ACRYLIC	URETHANE	UV	SILICONE	RUBBER
TOUGHNESS ABRASION RESISTANCE	Low	Medium	Medium	Low	Low
HIGH TEMP RESISTANCE	Low	Medium	Best	Best	Medium
FLEXIBILITY	Best	Medium	Best	Best	Best
THERMAL SHOCK RESISTANCE	Low	Medium	Best	Best	Best
MOISTURE RESISTANCE (MVP)	Medium	Medium	Best	Low	Best
SIR/MIR	Medium	Medium	Best	Medium	Medium
ENVIRONMENT	Med/Low	Med/Low	Best	Best	Low
MAIN FEATURES	General Purpose	Chemical Resistance	Environment, High Temp, Chemical Resistance, Volume Production	High Temp	Thermal Shock