To provide end users with an assurance of acceptability for newly developed conformal coatings, the Institute for Printed Circuits (IPC) developed the IPC-CC-830 Standard, which is a replacement for the MIL-I-46058C Standard, which was declared inactive in 1998. The IPC-CC-830 Standard very closely resembles the MIL-I-46058C Standard, testing the coating’s ability to withstand extremes such as temperature shock, moisture saturation, fire, fungus exposure and mechanical stress while maintaining its intended properties as a flexible, dielectric coating. The main differences between the two standards are the ability for the coating vendor to self-certify new coatings as compliant and the lack of a Qualified Product List (QPL).
The IPC-CC-830 determines a product’s fitness for use by subjecting the coating to various stresses common in electronic applications, such as thermal cycling, high humidity, fungal exposure, fire, and weathering. Following exposure, the coating is evaluated subjectively (appearance of defects like cracking, blistering, peeling) and often with a series of measurements to ensure the dielectric properties have not been compromised. Below are the specific tests involved in IPC qualification
Visual inspection of coated samples for defects
Aged sample checked for compliance with dielectric testing
Cured samples are inspected for evidence of cracking, tackiness or loss of adhesion
Uncured coating inspected for appearance of any deleterious substances
Coating inspected under black lamp to confirm presence of UV tracer dye
coated samples incubated and examined for bacterial growth
Coated tin panels bent 180 degree over mandrel to check for cracking, delamination
Coated FR4 strips set on fire. Flame progression measured over horizontal surface.
Coating thickness measured against compliance requirements
Dielectric Withstand Voltage
Coated samples subjected to 1500VDC for 1 min without discharge between traces
Moisture Insulation Resistance
Coated samples incubated in high humidity and 50VDC. Insulation of 5×109 Ω is required
Coating cycled between -65˚C and 125˚C for 24 hrs then measured for dielectric compliance
Coating subjected to high temperature and humidity and checked for gradual discoloration
Included in the Standard are QC tests like viscosity and Infrared scans to help coating users ensure batch to batch consistency
The IPC-CC-830 Standard has been amended over the years to reflect best industry practices. Currently the Standard is on revision C, which includes the following updates not present in revision B:
- Inclusion of 2 new coating types: ultra-thin (<12.5μm) and styrenated block-copolymer. This brings the total number of recognized IPC coating types to 8.
- Changes to the Dielectric Withstand Voltage Test. Prior revisions tested traces spaced closer together on a standard test board, whereas in this revision the traces are spaced further apart. See Figure 1, below, which illustrates this change.
The IPC has assembled a committee of professionals who meet regularly to discuss whether further amendments are needed to reflect current industry practices.
Figure 1: Depiction of changes made when measuring Dielectric Withstand Voltage for Revisions B & C
MG Chemicals has several IPC-CC-830 certified conformal coating products:
- Acrylic conformal coatings: 419C (revision B), 419D (revision B), 419E (revision C)
- Epoxy conformal coatings: 4225 (revision C)
- Polyurethane conformal coatings: 4223F (revision B)
- UV conformal coatings: 4200UV (revision C)