Conformal coating is applied to electronic circuits to provide a protective barrier to moisture and contamination and to provide electrical insulation. The most common specifications used for conformal coating testing are IPC-CC-830 and MIL-I-46058.
IPC-CC-830 is currently broken down into three categories: Column A testing for qualification, Column B testing for retention of qualification and Column C testing for quality conformance. MIL-I-46058 is broken down into four categories: Qualification, Group A, Group B and Group C. The testing frequencies for each specification are outlined below.
|Required Initially||Column A, Qualification Testing||Qualification Testing|
|Required Every 2 Years||Column B, Retention of Qualification Testing||Group C Testing|
|Required Every Year||Not Applicable||Group B Testing|
|Required on Each Batch||Column C, Conformance Testing||Group A Testing|
Although the MIL-I-46058 document has been canceled for new design since November of 1998, the Defense Logistics Agency (DLA) still maintains a Qualified Products List (QPL) for this document because the material is still being purchased for the manufacture of products that are being built to old military contracts. NTS is a DLA-approved testing laboratory for this specification and can supply full conformal coating qualification and conformance testing including assistance interacting with DLA to complete the necessary application form.
There is currently no QPL maintained for IPC-CC-830 qualified products although one is being developed by IPC. If you, the user, are responsible for supplier surveillance, we recommend reviewing your supplier’s actual dated test reports to confirm necessary testing is being completed.
NTS supplies consultation and testing services to conformal coating manufacturers and users including root cause failure analysis for adhesion, electrical, contamination and other issues.
|Test||Test Vehicle||Number of Specimens|
|1) Appearance||Glass||4 coated; 1 uncoated|
|2) Fluorescence||Glass||4 coated; 1 uncoated|
|3) Thickness||Glass||4 coated; 1 uncoated|
|4) Fungus Resistance||Glass||4 coated|
|5) Flexibility||Tin Panel||4 coated|
|6) Flammability||UL 94 test strips (1/2” X 5” bare laminate strips with the sides sanded)||20 coated|
|7) Dielectric Withstanding Voltage (DWV)||IPC-B-25A test boards (with the D-pattern wired)||5 coated|
|8) Moisture and Insulation Resistance (MIR)||IPC-B-25A test boards (with the D-pattern wired)||4 coated; 1 uncoated|
|9) Thermal Shock||IPC-B-25A test boards (with the D-pattern wired)||5 coated|
|10) Temperature and Humidity Aging (Hydrolytic Stability)||“Y” shape test assembly (with the resistors, one color coded and one with numbers/alphabets, soldered)||5 coated|