Help for Evaluating Conformal Coating

Conformal coating improves reliability of some printed board assemblies. Unfortunately, problems with coating selection or application may cause problems related to mismatched coefficient of thermal expansion (CTE), trapped moisture, outgassing, corrosion, abrasion or future rework/repair. To help users evaluate and identify conformal coating problems, IPC’s online store is now carrying two evaluation guides from Bob Willis, industry SMT guru. They are:

Conformal Coating Photographic Poster Guide

The 21-page color poster guide is ideal as a reference source for production, inspection and training departments who must evaluate and inspect conformal coatings. The individual .PDF sheets can be printed in standard or large sizes for bench top reference or for posters for reference in manufacture. Alternatively they can be viewed on a PC with each page featuring three images illustrating points to examine or steps in the inspection process. Currently the guide features 21 individual pages for on-site printing and display.

Conformal Coating Photo Guide on CD

This CD provides the process or quality engineer with 290 photographs for company inspection documentation or training presentations. Sample photos include: copper dendrites on the solder mask; black sulfur corrosion on chip capacitor termination under mask; dendrite formation on PCBA due to rework flux; corrosion under coating between terminations; solder balls under conformal coating; lifted chip under coating open circuit; lifted chip under coating open circuit resistor; solder balls under conformal coating and many more.

And don’t forget, IPC has several standards on conformal coating as well. Conformal coating users will get great benefit from IPC-HDKB-830. A separate standard, IPC-CC-830, provides coating material qualification requirements but does not provide criteria for using the coatings.

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

This handbook is a compilation of the conformal coating industry’s practical experience, and will assist the designers and users of conformal coatings in making informed choices. Users will better understand the properties of the various conformal coatings, the results to be achieved by its application and how to verify that these goals have been met. Use this document as a supplement in conjunction with the industry standard for qualification and quality conformance of conformal coating, IPC-CC-830B. 88 pages.

8 Comments

  1. Posted August 11, 2009 at 8:44 am | Permalink

    it seems that not all sucontractors now that the cleanliness is required for all type of cc

  2. Posted November 26, 2009 at 10:21 am | Permalink

    I’ve worked with some printed board assemblies in the past and at times I did struggle with selecting the right coating. I found that there was often too much information to sift through. I wished that I had resources like these in my last position – it would have saved me a lot of work.

  3. Posted December 19, 2010 at 11:46 pm | Permalink

    Thank you for sharing the information with us. i have looked for the information related to the corrosion for a while, and finally i get this post.

  4. Posted April 27, 2011 at 10:25 am | Permalink

    What are the differences between the IPC-HDBK-830 and the CD available at this link https://portal.ipc.org/Purchase/ProductDetail.aspx?Product_code={7345B7C3-5C3A-DF11-AA66-002219545FD5} ?

    I am interested in buying the CD but I wish to know if topics here are not identical to that in IPC-HDBK-830. Thanks.

  5. Posted April 28, 2011 at 9:30 am | Permalink

    Hello Tomas – Here is the answer I received from Bob Willis, author of the interactive CD:

    The Conformal Coating interactive CD, and the other Photo CD ROM are both for training where as the standard is for reference.

    The photo CD has hundreds of images to include in presentations for training. The interactive CD ROM covers all of the process, materials rework and inspection steps but also includes an interactive defect guide where you can print out defect examples. It also includes interviews with many engineers on process issues on coating. I would say each of the products I have produced complement the IPC standards.

    Many thanks

    Bob Willis
    2 Fourth Ave, Chelmsford, Essex, CM1 4HA England
    Tel: (44) 1245 351502
    Fax: (44) 1245 496123
    Mobile: 07860 775858
    http://www.PackageOnPackage.co.uk
    http://www.ASKbobwillis.com
    http://www.BobWillisOnline.com

  6. Corby II
    Posted November 29, 2011 at 12:55 pm | Permalink

    What a frankly good blog post!

  7. victor powell
    Posted November 30, 2011 at 4:21 pm | Permalink

    Can anyone direct me to the IPC document or tell me the conformal coat adhesion test needed to determine proper coating of PWA’s?

    • Kim Sterling
      Posted December 1, 2011 at 9:52 am | Permalink

      Thanks for the question.

      From John Perry, IPC technical project manager:

      Qualification of the conformal coating material itself: IPC-CC-830B
      Acceptable level of application to the printed board assembly (e.g., thickness, coverage): IPC-J-STD-001E
      Fun stuff to know about conformal coating types, their properties and application methods: IPC-HDBK-830.
      IPC standards with table of contents can be found at http://www.ipc.org/onlinestore.
      You can reach John directly at JohnPerry@ipc.org or answers@ipc.org.


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