Asymtek's Jet Dispensing Precisely and Accurately Dispenses Catalyst Ink of Fuel Cell Membranes

Asymtek, leader in dispensing technology and pioneer in jetting technology, introduces two coating/dispensing technologies for applying catalyst inks onto membranes in electrode assemblies of proton exchange and direct methanol fuel cells. Pulse spray coating technology provides quick large area coverage, allowing for uniform film thicknesses. DispenseJet technology deposits the ink with a uniform thickness and density so lines and patterns are smooth, even, and the same consistency throughout. The consistent and precision application of the ink increases the porosity of the film so fuel and byproducts can pass through the membrane efficiently.

Asymtek offers fuel cell manufacturers two types of application technologies for increased dispensing flexibility: spray coating and discrete dot dispensing. Spray coating is for large areas, for controlled thicknesses, and even film thicknesses. Discrete dot dispensing is used for specific patterns with high edge definition and exact film build up of highly volatile inks. Asymtek has a multiple array of coating and dispensing technologies for catalyst inks, polymer electrolytes, gasketing, and sealing depending on the application.

Catalyst inks are very expensive because of the platinum content. With the Asymtek jet, the ink is deposited precisely where it is programmed to be placed, so there is limited waste. The jet deposits discrete dots in whatever pattern is desired without masking. Asymtek’s closed-loop system measures the exact amount of fluid that’s deposited. Process controls and Asymtek’s Easy Coat^® for Windows XP^® (ECXP) software regulate the volume, size, shape, and viscosity of the dot.

Selective spray coating is a highly selective method of jetting materials and enables fluid to reach locations not possible with other applicators. Dot sizes to 1.2mm (0.05 in.) are possible as well as thinner film builds of 5µm. Jetting is fast, up to 500mm/sec (20 in/sec), because there is no Z-axis motion. The system is so accurate that it eliminates the need for masking. The system is easy to disassemble and maintain.

Discrete jet dispensing allows material application in tight spaces as small as 175 microns with final dot diameters as small as 200 microns. Shot volumes of 1.0 nanoliter are possible and the jet stream size can be as small as 50 microns. Fluids from 1 to 250,000 mPa (cps) can be jetted. As with coating, this is a very fast system. The system jets "on the fly" with no stopping between dots required at a rate of 200 dots per second.

“The success of the catalyst ink depends 50% on its chemistry and 50% on its application,” said Jim Klocke, Asymtek senior business development manager. “While most application methods use spray technology, the catalyst inks may vary in thickness and density. With Asymtek’s jet dispensing, all those problems are eliminated and the ink is deposited precisely, with uniform thickness and density.”