R&D BULLETIN THICK FILM TECHNOLOGY Thick film technology is simply a technique for applying a layer of material onto a substrate. Layer thickness can be varied from 5 to several hundred microns but typically are about 25. Thick film technology is widely used in the electronic industry for the preparation of hybrid circuits. Thick film layers are applied and processed in powder form. The layer material is mixed with polymer and glass binders, used to give the thick film layer both strength and adhesion to the substrate and temperature depending electric properties. A heavy organic solvent is also added to form a thick film ink of a viscosity suitable for a screen printing process. The ink is printed as an image through a mesh screen onto the substrate, dried to remove most of the organic medium (100°C-200°C) and fired (450°-900°C) to form a continuous layer with specific electrical behaviour and tolerances. A layer containing Ag/Pd, Ni/Cr, Mo or C powders printed in the form of a resistive track onto an insulating substrate has potential applications as a heating element. The ink composition governs both the electric (O/sq and TCR) and mechanical (adhesion, TCE) behaviour of the thick film layer. By changing the powder composition, dielectric or conducting areas can be printed as well. By selection of the binder material and processing conditions it is possible to apply several thick film layers onto many different substrates, including 300 and 400 series stainless steel, aluminium, ceramics, glass and mica foils. Printable shapes may be both flat and circular. Cermet and polymer thick film heating elements have several attractive properties including thin section, direct application to the surface to be heated, rapid response, high power density support, flexible design and power pattern, NTC/PTC control integration. Multiple heating elements and varying power outputs can be incorporated across a single substrate in order to get the requested temperature distribution. Max temperature of operation depends upon the substrate and the dielectric thickness, ranging from 200°C up to 600°C. Different resistor paste formulations fix a wide range of O/sq and TCR (Temperature Coefficient of Resistance, in ppm/K) enabling several options in terms of circuit design and product behaviour. Pd/Ag Ni/C r Mo C O/sq 0.1 .. 0.2 0.2 .. 2.0 50 .. 1000 2 .. 200 ppm/K 300 .. 3500 400 .. 600 -400 .. 400 -500 .. –1000 Depending on the heat transfer conditions the watt densities on the hot track can be raised up until 100 watt/sqcm. At the upper limit, in static air conditions, a Thick Film heater provide a thermal response of about 300°C/sec. Silver based terminations / pads are suitable for soldering or mechanical contact. Solderable pads for electronic component attachment (SMD) can be built onto the substrate as well. All these features make Thick Film heaters a smart solution for improving appliance performances and efficiency while reducing the global cost of the host application. Applications include tea kettles, waffle irons, clothes dryers, stove top burners, humidifiers, water heaters, boilers, thermal print heads, glue guns, ceiling heating panes, acquarium, fridge defrosting, deicing or demisting devices, warming tray, car reversing mirror, evaporators, plate exchangers, just to list some of them. Thick Film heaters offer a 2D-profile design that can be fitted into appliance framework, hydraulic and mechanical parts. Due to low thermal mass and excellent heat transfer, Thick Film heaters have proven to be energy-efficient heat sources, leading to space, time, energy and water savings. Another advantage of Thick Film heaters deals with quality issues. In fact, due to the heating element structure, traditional failures due to moisture adsorption and electrical leakage are avoided. 11/2003 - 07 All the Thick Film elements are designed and tested to withstand 2000 V dielectric breakdown. That value is achieved by appropriate insulating layers depending on substrate properties and working temperature. The data presented in this brochure are in accordance with the present state of our knowledge. We reserve the right to change product data within the scope of technical progress or new developments. The recommendations made in this brochure do not absolve the user from the obligation of investigating the possibility of infringement of third parties’ rights and, if necessary, clarifying the position. Recommendations for use do not constitute a warranty, either express or implied, of the fitness or suitability of the product for a particular purpose.

R&D BULLETIN POLYMER THICK FILM HEATERS WITH PTC EFFECT An innovative technology for integrating compact, efficient, reliable and safe heating elements onto the surface of mechanical and hydraulic parts of domestic appliance, professional and industrial equipment, transport and garments is available through the R&D facility of IRCA Group. The heating elements are built by screen printing a number of Polymer Thick Film (PTF) electric circuits onto a wide range of substrates, including metals, ceramics, glass, mica, plastics, polyimide and polyester foils, adhesive transfer tapes, textile materials,...

R&D BULLETIN POLYMER THICK FILM HEATERS WITH PTC EFFECT TYPICAL PROPERTIES PROPERTIES RATINGS • Specific resistance range • 1,000 – 90,000 ohm/sq • Average TCR range • 5,000 – 300,000 ppm/°C • Switch-off temperature range • 50 – 150 °C • Heat-up rate Depends on power density, substrate thermal mass and heat transfer conditions • Useful power density (at working temp.) Depends on substrate and heat transfer conditions, typically being: • Max temperature of operation • Up to 100 °C/sec • Less than 1.0 watt/sqcm in still air • Less then 2.0 watt/sqcm in forced air • Less than 4.0 watt/sqcm for water...