Dielectric coatings—also known as thin-film coatings or interference coatings—provide shielding for radio-frequency applications. Sub-micron layers of dielectric materials applied to surfaces on thin metal parts can provide the shielding necessary for printed circuit boards (PCBs), micro sub-assemblies, and many other types of electronics.
Given tolerance requirements on electronic components are often extremely tight, there is no space for coatings that are not precisely fabricated to an exact thickness. Precision is vital for the application of interference coatings, which are used in electronics and semiconductors across industries, including aerospace, defense, and medical.
Dielectric Coating Process
Dielectric coatings work by reflecting the interference from multiple interfaces away from sensitive electronic components. These coatings may be used in applications such as:
- Transformer turns
- RFI shielding
- Laminations in small motors
- Additional protection for conductive surfaces
- Heat dissipation for PCBs or thin metal parts
All dielectric coatings must meet specifications for good isolation and thickness:
- The high potential (Hi-Pot) specification for thin-film coatings can be tested at 5,400 V/mil, compared to a typical 800 V/mil for powder-coated electrical insulation.
- Thickness is determined by customer requirements. Copper, brass, and aluminum surfaces as large as 12” by 12” or 12” by 24” may be coated to specification.
Designing dielectric coatings involves a choice of one or two materials and consideration of the necessary layers and their thickness values. Our process can be used to apply a single layer of thin-film coating or several layers, depending on project requirements.
The process for EMI and RFI shields is done when components are in panel form. That way, coating materials do not fill or mar bend lines. This permits a low-profile shield design, which is useful in many small electronic parts.
Dielectric Coating Capabilities
Our engineers at E-Fab pride themselves on finding solutions for any client need. We began applying dielectric coatings as a small process for one customer. This type of thin coating on circuit boards was not available from similar companies, and we quickly found that there is a larger market need for the service. Through the creation of proprietary processes and testing, E-Fab has been able to offer interference coatings to customers in multiple industries.
Our system yields Hi-Pot tests up to five times higher than powder coating when tested on PCBs and thin metal parts. Our dielectric coatings meet Hi-Pot 800 volt standards and we triple the thickness to allow approximately 2000 volts. Quality control ensures uniform thickness of applied coatings and strong adhesion and durability.