Customer Challenge:
Conductive coatings are used to shield circuits from incoming electromagnetic and radio frequency interference (EMI/RFI). With this technology, spectroscopic tools that measure responses of an unknown substance to a specific electric field can be made portable since the application of conductive coating around the device effectively filters out unwanted noise. Ion Mobility Spectroscopy (IMS) is a technique that measures the mobility of ions in a carrier gas when subjected to an electric field. Today, the technique is widely used in scanning devices to screen trace quantities of hazardous materials in chemical vapours such as explosives and narcotics. For the customer, the challenge was to find a cost-effective material to conformally coat the inner shell of a portable scanning device while providing broadband shielding against external electric fields.
KEY CUSTOMER REQUIREMENTS
- Strong Adhesion to ABS plastic
- >40dB attenuation at frequencies above 60 MHz
- Strong cohesive strength to ensure conductive particles do not migrate and cause shorting
SOLUTION
MG Chemicals 841AR is a 1-part, electrically conductive coating that adheres strongly to many plastics. It uses a specially engineered Nickel flake with a high aspect ratio (high surface area relative to thickness) to help achieve a very smooth cured film with very good cohesive strength, ensuring the flake does not become labile and cause incidental shorting. The customer was able to successfully apply the coating to the inner shell of the scanner in one step, avoiding the use of a pretreatment or primer. The coated scanner achieved sufficiently high shielding from external electric fields enabling it to make accurate measurements within noisy environments.
CONCLUSION
Portable scanning tools often require complete isolation from external interference sources to function properly. A solution to this requirement is the application of conductive coatings which attenuate external EMI/RFI, preventing unwanted noise from disrupting measurements. The 841AR is a simple 1-part Nickel conductive paint that attains primerless adhesion to many common plastics like ABS. It applies conformally to complex geometries, ensuring complete coverage and no gaps in the conductive layer. These properties coupled with the coating’s exceptional EMI suppression enable intricate measuring instruments like IMS scanners to work within noisy environments.
