Thick Film FAQs

Watlow's new thick film heaters are now available using an assortment of ceramic materials as the base substrate. This high performance heater uses thick film technology to provide maximum temperature response in a compact package. Ceramics provide low thermal expansion, a high temperature tolerance, a lower dielectric constant, rigidity and dimensional stability; making it a preferred substrate for many applications.

Thick film on ceramic substrates provides a low-profile heater that can be special ordered to fit any CAD-generated, two-dimensional shapes. Due to the direct surface contact, these thick film heaters ensure greater heat transfer through the thermally stable ceramic substrates. The bottom of this page includes a description of each ceramic substrate available for thick film applications.

Ceramic substrates are mainly composed of powdered metal oxides or nitrides combined with glass or frit particles. The mix of these materials is varied to generate a range of physical properties. The mixture is shaped into its desired form by either tape casting, powder pressing, roll compacting, or extrusion, and then sintered in to form a hard crystalline structure.

Thick film heaters on ceramics can be applied in areas where space is at a premium or where conventional heaters cannot be used due to the voltage and wattage combination preventing the usage of other types of resistive heaters. Because of the unique nature of thick film circuit, this heater can be designed to vary heat output across the entire surface. This feature will correct virtually any temperature uniformity problems a current design is generating.

Watlow's thick film heaters are manufactured to meet the requirements of NEC codes with UL® and CSA. Certifications are pending.

• Up to 480 Volts, 3-phase

• Fast response to power input due to low thermal mass

• 932°F (500°C) maximum substrate temperature

• Provide uniform heat with see-through option
• Capable of extremely uniform temperature distribution utilizing infrared thermal scanning technology and finite element analysis
• Improve process quality and yield

• Watt densities: 20 W/in² for open air applications, 50 W/in² for clamp-on applications, 175 W/in² for immersion applications

• Precise, repeatable wattage distribution places heat directly where required

• Termination options include contact pad, epoxied, soldered or welded lead connector

• Substrate material offers excellent corrosion resistance

• Bonded RTD, epoxied thermistors, attached thermocouples plus full control integration

• Low profile package fits into tight spaces
• Able to design heater around existing mounting holes, notches, sensors, etc.

• Thermally stable ceramic heating surface

• Moisture resistant glass material eliminates moisture problems and has low current leakage

• Semiconductor: Susceptor plates, integrated circuits
• Life science: Thermal cycling, sample analysis
• Digital printing and laser copying
• Analytical equipment: Gas chromatography and spectroscopy
• Packaging: Seal bars, seal rams

Aluminum Nitride (AlN) - This material has high thermal conductivity making it an excellent choice where fast response or high levels of uniformity are required. Aluminum nitride is costly to fabricate due to high temperature atmosphere required for firing requirements and material costs.

Beryllium Oxide (BeO) - This material has the highest thermal conductivity available and has excellent dielectric strength needed for some applications. Beryllium oxide is available only in small sizes and safety can be a concern when dealing with toxic beryllium oxide powder.

Silicon Carbide (SiC) - This ceramic is also highly conductive and offers an alternative to aluminum nitride and beryllium oxide. Caution must be used when selecting silicon carbide substrates as dielectric strength can vary as temperature increases.