Conformal coating standards

Co-Authors and contributors

  • Dr Lee Hitchens, Nexus

There are International, National, National Trade Bodies and internal company standards for conformal coating processing and inspection.

The role of the standard is to give a guideline for users on the quality of the product.

For Conformal Coating Standards there are two areas that they cover.

These are:

The conformal coating material manufacture standards are used for making the conformal coating. They are only really relevant to suppliers so that they can measure their coating performance against a set of tests.

The conformal coating production standards are used for qualifying a process. They are used by the end users of the coating material in the production environment.

These two areas are examined in more detail below.

The conformal coating material manufacture standards are used for making the conformal coating. The conformal coating production standards are used for qualifying a process.
The conformal coating material manufacture standards are used by the suppliers for making the conformal coating. The conformal coating production standards are used by engineers for qualifying a process.

 

Conformal coating manufacture

These conformal coating standards are used for the manufacture of the conformal coating.

They include:

  • MIL-I-46058C
  • Underwriters Laboratories (UL)
  • IPC-CC-830B
  • IEC 61086-1 ed2.0

As stated these conformal coating standards are written for the manufacturer of the conformal coating and used for the manufacture of the Coating.

These conformal coating standards can also be split in two other ways.

  • Self-Certification: Those that the manufacturer follows and completes the testing themselves on their own conformal coatings.
  • Independent: Those standards that are completed by independent laboratories on the customer coatings.

These common standards used in conformal coating are summarised below and on individual pages.

MIL-I-46058C

  • The Mil Standard for conformal coating has been inactive for new designs since November 1998. However, the standard is still widely used for independent certification of conformal coatings.
  • All companies tested to the Mil standard are listed on a Qualified Product List (QPL). Conformal coatings listed on the QPL will have been through rigorous 3rd party testing.
  • Caution should be shown when examining conformal coating datasheets which state MEET the requirements of MIL-I-46058C since they conformal coatings will likely not have been tested by the independent laboratory.

Click to read about the Mil-I-46058C Standard in more detail.

Underwriters Laboratories (UL)

  • UL are a global safety certification body for consumer electronics.
  • For conformal coating, two parts of the standard are important, being UL 746 and UL94.
  • UL 94 measures conformal coating material’s tendency either to extinguish or to spread the flame once the test specimen has been ignited.
  • The first program is described in UL 94.
  • This is now harmonized with IEC 60707, 60695-11-10 and 60695-11-20 and ISO 9772 and 9773.
  • UL 746E measures the ignition resistance of the conformal coating to electrical ignition sources.
  • The conformal coating material’s resistance to ignition and surface tracking characteristics is described in UL 746E.

Click to read about the UL Standards in more detail.

IPC-CC-830B Qualification and Performance of Electrical Insulating Compound for Printed Wiring Assemblies

  • The CC-830 standard is written for manufacturers of electrical insulating compounds (conformal coatings).
  • It covers the qualification of the conformal coating and the conformance of the material.
  • Although the standard is Self Certification it is possible to have 3rd parties complete test work to the standards.

Click for the IPC Standards in more detail.

IEC 61086-1 ed2.0 Coatings for loaded printed wire boards (conformal coatings) – Part 1: Definitions, classification and general requirements

  • The IEC (International Electrotechnical Commission) provide International Standards and Conformity Assessment for all electrical, electronic and related technologies.
  • The standard gives the definitions, classification and general requirements for electrical insulating materials suitable for application as coatings for loaded printed wire boards (conformal coatings).
  • This standard excludes requirements for compatibility between such coatings and printed wire boards, this characteristic being evaluated in individual applications.

Click to read about the IEC 61086 standard in more detail

Conformal coating production process

The production process conformal coating standards are used by the end user of the coating in the Production Environment.

They include:

  • IPC A 610 Acceptability of Electronic Assemblies
  • IPC-HDBK-830 Guidelines for Design, Selection and Application of Conformal Coatings

These common standards used in conformal coating are summarised below and on individual pages.

IPC A 610 Acceptability of Electronic Assemblies

  • IPC-A-610, Acceptability of Electronic Assemblies is the most widely used standard published by the IPC.
  • It is a source for end product acceptance criteria for consumer and high reliability printed wiring assemblies.
  • However, for conformal coating, the standard only gives some minor references which are of limited help except for specifying acceptance criteria.
  • It is also a self-certifying standard.

Click for the IPC Standards in more detail

IPC-HDBK-830 Guidelines for Design, Selection and Application of Conformal Coatings

  • The IPC Conformal Coating Handbook is a compilation of the conformal coating industry’s practical knowledge and will help designers & users of conformal coatings to understand the practical implications of selection, application and inspection, explaining in detail how to achieve the best results.
  • The IPC-CC830 was originally written as an alternative to MIL-I-46058C and is used in conformal coating all over the world.

Click for the IPC Standards in more detail.

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