Thick Film Technology
Thick film is used to make electronic devices such as PCB's and sensors. Using this technology involves the deposition of several successive layers of conductor, resistors and dielectric layers onto an electrically insulating substrate using a screen-printing process. The Thick film process involves many steps that involves a lot of preparation along with a clean work environment.
A product that is using thick film technology is built by screen printing different thick film ink layers onto a base substrate. The base substrate can be a number of different materials: ceramic, stainless steel and in some applications, aluminum.
The thick film inks used to make thick film products are broadly distributed into 3 categories: Dielectrics, Conductors and Resistors. The dielectric materials are generally glass and ceramic based and are not conductive. The conductors contain precious metal particles such as silver, palladium, gold or platinum and their alloys. Resistors are blends of glasses, metals and metal oxides such as silver and ruthenium in various combinations to achieve inks with different resistance values. All the ceramic based thick film inks are blended with glass particles called frit. During the firing process the metal and metal oxide particles bond together in a solid state process called sintering to form a network of millions of electrical connections between the conductive particles. Also during the firing process the glass particles melt, flow and act as an adhesive and filling voids between particles of metal and metal oxides and bonding the entire structure together and to the base substrate.