Mr. Stadem's comment about conformal coating wicking is true. I have seen instances where it got inside connectors making them impossible to connect or gluing them shut.

  The IPC should make recommendations regarding conformal coating masking in their hand book. Should it be left on after coating? Subject to qualification?

  Mr. Stadem is mistaken regarding conformal coating and "moisture condensation". Moisture yes, condensation no. A lot of other engineers make this incorrect assumption. Conformal coating applied as liquid doesn't provide water proofing on 3 dimensional objects. If it's expected to then the qualifying tests should be changed.

  Dipping is a good way to apply conformal coating and dipping with a machine gives better results than dipping by hand. Many companies that dip by hand do so because they don't have to invest in equipment. Many of the companies that would benefit from coating by dipping chose not to because of the time necessary to coat each board.  My former employer used to sell the dipping machines that Mr. Naisbitt's company manufactures.

  Mr. Naisbitt's comments about hand dipping resulting in a coating too thick are correct in some instances but the viscosity of the coating solution can be adjusted by adding more thinner until the target thickness is achieved.  A few hand dippers dip twice in diluted conformal coating, reversing the edge on top for the second dip.







Edward Mines BEChE, MEChE
238 Willard Dr.
Hewlett, NY  11557
516 205-6523

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