Silver-Filled Epoxy Shielding Coating Using Ultrasonic Spray Deposition
Ultrasonic coating technology, followed by a low temperature heat cure, offers a cost-effective alternative to costly sputtering-based coating equipment for package-level Electromagnetic (EMI/RFI) shielding coating processes. High performance silver EMI coating materials are applied with Sono-Tek’s FlexiCoat fully automated XYZ motion coating systems in mobile device manufacturing processes. FlexiCoat is available as an in-line conveyor configuration for high throughput processes.
Sono-Tek’s non-clogging ultrasonic coating technology is well known for ultra-thin micron layer coatings of functional and protective materials. The ultrasonic vibration of the nozzle effectively disperses particles in suspension and produces very uniform dispersion of particles in thin film layers without conductive particle settling out of suspension.
Spray-on silver-filled epoxy shielding materials have been in use for several years. Thinner, lighter device designs have made the transition from board level shielding to package-level shielding, enabling higher board density. Silver-filled polyester coatings are applied using ultrasonic spray following package placement as an alternative to sputtering.
At a fraction of the cost of sputtering technology, Sono-Tek ultrasonic coating systems have been used as CVD alternatives where cost savings is a significant concern during manufacturing. Effective EMI shielding coatings enable high processing speeds without operational disruption performance issues from neighboring device electromagnetic field interference.
Benefits of ultrasonic coating technology for EMI shielding coating processes include:
- Complete thin film coverage of geometries with excellent uniformity
- High throughput (UPH)
- Excellent surface conductivity due to homogeneous distribution of particles
- Highly effective shielding of small devices
- Optimal side wall coverage in tight geometries, with ultrasonic nozzle tilt
- Precise thickness control
- Flexible, programmable nozzle tilt and rotate capabilities
- No backside contamination
- Adhesion performance proven to be excellent
- Simple, cost effective technology compared to sputtering
- Common materials for use: LOCTITE Ablestik EMI8605, Parker Chomerics CHO-SHIELD 608
The heart of all Sono-Tek spray systems is our patented ultrasonic spray nozzle, which uses high frequency sound vibrations to produce a soft mist of mathematically defined droplets. This eliminates clogging, since no pressure is used to produce the spray, and the droplets have a very narrow drop distribution size, further contributing to uniformity of the layer deposited. Go to http://www.sono-tek.com/how-ultrasonic-nozzles-work/ for more information.