Thick film heaters are commonly used in various applications, including industrial, automotive, and consumer electronics. These heaters are made by depositing a thick film of resistive material on a substrate. The choice of materials for thick film heaters depends on factors such as the operating temperature, power requirements, and the specific application. Here are the commonly used materials in the manufacturing of thick film heaters:
1. Substrate: The substrate provides mechanical support for the heater and can be made of materials like alumina (ceramic), stainless steel, or glass-ceramic. Alumina is a popular choice due to its excellent thermal conductivity and electrical insulation properties.
2. Resistive Material: The resistive material is the key component of the thick film heater. Commonly used materials include:
Silver Palladium (AgPd): Silver-based materials like silver palladium are often used due to their high electrical conductivity and stability at elevated temperatures.
Platinum (Pt): Platinum-based materials are suitable for high-temperature applications due to their excellent corrosion resistance and stability at high temperatures.
Gold (Au): Gold-based thick film heaters are used in applications where corrosion resistance is essential. Gold has good stability and is resistant to oxidation.
Cermet (Ceramic-Metal Composites): Cermet materials combine ceramic and metal particles, offering a balance between electrical conductivity and mechanical strength.
3. Dielectric Material: Dielectric layers are used to insulate the resistive elements and prevent electrical short circuits. Common dielectric materials include glass-based compositions.
4. Conductive Traces: Conductive traces are used to connect the resistive elements and form the desired heating pattern. Silver-based conductive inks are often used for this purpose due to their high conductivity.
5. Terminal Material: Terminals are used for electrical connections to the external circuit. Materials like silver or silver-plated materials are commonly used for terminals due to their good conductivity and solderability.
6. Protective Coatings: In some applications, a protective coating is applied to enhance the durability and resistance to environmental factors such as moisture and chemicals.
The manufacturing process involves screen printing or other deposition techniques to create the desired pattern on the substrate. After deposition, the thick film heater is fired at high temperatures to sinter the materials and ensure good adhesion to the substrate.
It's important to note that the specific choice of materials can vary based on the requirements of the application and the manufacturer's preferences for performance, cost, and reliability.
