How the five IPC coating types compare on thickness, temperature, rework and protection, and which one fits your assembly.
Conformal coating services › Conformal coating types
There are five main types of conformal coating, identified by IPC type codes: acrylic (AR), epoxy (ER), polyurethane (UR), silicone (SR) and parylene (XY). The first four are liquids that are sprayed, dipped or brushed on and then cure. Parylene is deposited from vapour. They differ most in how hard they are to remove for rework, how much heat and chemical exposure they tolerate, and how thick they are applied. This page compares all five and shows which one usually fits which job.
| Type (IPC code) | How it is applied | Typical thickness | Typical maximum temperature | Ease of rework | Main strength |
|---|---|---|---|---|---|
| Acrylic (AR) | Spray, dip or brush | 30 to 130 microns | Up to about 125°C | Easiest: removed with mild solvents | Simple to apply and repair, good moisture protection |
| Epoxy (ER) | Spray, dip or brush | 30 to 130 microns | Up to about 150°C | Difficult: hard film | Abrasion and chemical resistance |
| Polyurethane (UR) | Spray, dip or brush | 30 to 130 microns | Up to about 125°C | Difficult: resists solvents | Long-term chemical resistance |
| Silicone (SR) | Spray, dip or brush | 50 to 210 microns | Up to about 200°C | Moderate: needs specific strippers | Heat, flexibility and humidity resistance |
| Parylene (XY) | Vapour deposition | 10 to 50 microns | Depends on the parylene type | Hardest: laser ablation or micro-abrasion | Thin, even coverage of every exposed surface |
Thickness ranges are the IPC-A-610 figures as published by Specialty Coating Systems. Temperature figures are the typical maximums quoted by Conro Electronics, a UK coatings distributor. Individual products vary, so always check the datasheet of the specific coating against your operating conditions.
Acrylic is the most widely used general-purpose coating. It dries quickly, gives good protection against moisture and humidity, and can be removed with relatively mild solvents such as isopropyl alcohol or xylene, which makes repair straightforward. That same ease of removal is its main weakness: acrylic gives less protection where the assembly meets strong solvents. Specialty Coating Systems gives 125°C as the maximum continuous operating temperature of one of the most popular acrylic coatings.
Epoxy cures to a hard, tough film with good resistance to abrasion, moisture and chemicals. The hardness that protects the board also makes it difficult to remove, so epoxy suits assemblies that are not expected to be reworked.
Polyurethane, often called urethane, is chosen for long-term resistance to chemicals and solvents. Like epoxy, that resistance makes it difficult to strip for rework, so plan any repair access before coating.
Silicone stays flexible after curing and copes with the highest temperatures of the liquid types, which suits assemblies that see heat or thermal cycling. It is applied thicker than the other liquids, at 50 to 210 microns in the IPC-A-610 ranges, and is softer, so it gives less abrasion resistance.
Parylene is a different process altogether. It is deposited as a vapour under vacuum and forms directly on every exposed surface, so it coats edges and tight gaps evenly at 10 to 50 microns. It resists solvents, which also makes it the hardest coating to remove for rework. Our parylene vs conformal coating page covers that choice in detail.
Neither is better in general. Choose acrylic when the board sits in a normal operating environment and may need rework, because it is easier to apply, inspect and remove. Choose silicone when the assembly runs hot, sees wide temperature swings or flexes, because silicone tolerates higher temperatures and stays flexible. Silicone is applied thicker, so check clearances around tall components and connectors.
Yes. Epoxy is one of the IPC conformal coating types, code ER. Searches for "epoxy vs conformal coating" usually mean epoxy compared with the more common acrylic. The trade-off is protection against rework: epoxy is tougher and more chemical resistant, acrylic is far easier to remove and repair. Epoxy potting, where the whole assembly is encased in a thick block of resin, is a different process. See conformal coating vs potting.
Liquid conformal coatings are polymer resins, acrylic, epoxy, polyurethane or silicone, supplied either in a solvent that evaporates as the coating dries or in solvent-free forms that cure, for example by UV light. Parylene starts as a solid powder that is vaporised and converted to a gas, which then forms a polymer film on the parts in a vacuum chamber.
Our suggestion is to answer three questions in this order:
Thickness also matters for fit and inspection. Our conformal coating thickness page sets out the ranges and how they are measured.
Systemation Euro offers liquid conformal coating to the coating you specify, applied by spray, dip, hand or gel, and parylene coating, with plasma cleaning where a surface is hard to coat. Every job includes cleaning, masking, de-masking and inspection, with a certificate of conformity if required. If you are unsure which type you need, tell us the environment and your specification and we will advise.
Acrylic (AR), epoxy (ER), polyurethane (UR), silicone (SR) and parylene (XY). The first four are liquid coatings that are sprayed, dipped or brushed; parylene is applied by vapour deposition.
Acrylic is the most widely used for general circuit board protection, because it is easy to apply, inspect and remove for repair.
Of the liquid types, silicone is typically rated highest, up to about 200°C according to Conro Electronics. Always check the datasheet of the specific product.
Acrylic. It can be removed with relatively mild solvents such as isopropyl alcohol. Epoxy, urethane and parylene are much harder to remove.
Sources: Specialty Coating Systems, Conformal Coating Specifications (IPC-A-610 thickness ranges); Specialty Coating Systems, Comparing Parylene and Acrylic (acrylic rework, 125°C example, parylene removal); Conro Electronics, Types of Conformal Coating (typical temperature maximums and properties). Supplier sources; check product datasheets and the current revision of each standard.
Tell us the assembly, the operating environment and any specification you work to, and we will advise on the coating. Add a phone number if you would like a call back, or call us on 01604 491107.
Converting, programming, testing, and packaging electronic components for defence, aerospace, automotive, and medical manufacturers since 1992.
Tel: (01604) 491107
info@systemationeuro.com
Systemation Euro Automotive Ltd
19 Mansion Close
Moulton Park Industrial Estate
Northampton
NN3 6RU
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