Thick film low resistance resistors (usually in the milliohm range) play an important role in modern electronic circuits, especially in applications such as current detection, power management, and power distribution. Compared to other technologies such as thin films, metal foils, or wire wound resistors, thick film low resistance resistors exhibit some unique advantages:
Excellent cost-effectiveness and manufacturability:
Mature process: Thick film technology is a mature and highly automated production process, particularly suitable for large-scale manufacturing.
Substrate compatibility: It can be directly printed and sintered on ceramic substrates such as alumina or aluminum nitride, compatible with many power electronic module substrates, and easy to integrate.
Material cost: Compared to resistors that require precision alloy foil or special winding materials, the raw material cost of thick film resistor paste is usually more advantageous, especially for low resistance resistors produced in large quantities.
Integration capability: It can be printed together with other thick film components (capacitors, conductors) on the same substrate to form hybrid integrated circuits, reducing the number of discrete components, assembly steps, and overall costs.
Excellent high current carrying capacity:
Thick film characteristics: As the name suggests, the thickness of the resistance layer of thick film resistors is much greater than that of thin film resistors (micrometer vs. nanometer). This larger physical thickness provides a larger cross-sectional area of the current path.
Heat dissipation foundation: The ceramic substrate itself has excellent thermal conductivity, and the thick resistor layer is tightly bonded to the substrate, which facilitates the conduction and dissipation of heat from the resistor to the substrate.
Power density: Thick film technology can achieve higher rated power within a given package size, which is crucial for low resistance applications that require handling high currents, such as current sensing resistors.
Good structural strength and reliability:
Sintering bonding: After high-temperature sintering, the thick film resistor paste forms a strong metallurgical bond with the ceramic substrate, and the structure is very strong.
Mechanical robustness: This structure gives it excellent resistance to mechanical impact, vibration, and bending, making it suitable for harsh environments such as automotive and industrial applications.
Thermal stability: Thick film resistors can typically withstand high overload currents and temperature cycles, and their structure is less prone to cracking or failure due to differences in thermal expansion coefficients (compared to some thin film or precision foil resistors).
Design flexibility and resistance range:
Slurry formula: By adjusting the proportion and type of conductive phases (such as silver, palladium silver, and ruthenate) in the resistance slurry, different square resistance slurries can be designed.
Geometric design: By utilizing the flexibility of screen printing, it is easy to accurately set low resistance values by changing the aspect ratio (L/W) of the resistor body. A short and wide resistor pattern is an effective way to achieve milliohm level resistance.
Low TCR selection: Although the absolute TCR of thick film resistors is usually not as good as metal foil or precision thin film resistors, low resistance thick film resistors with lower and relatively stable temperature coefficient (TCR) can also be manufactured through special paste formulations (such as copper, nickel, etc.), meeting general current detection needs.
Relatively good surge tolerance:
Due to its body structure and good heat dissipation combination with the substrate, thick film low resistance resistors are usually better able to withstand short-term high current pulses (surge currents) than thin film resistors, which is important in scenarios such as power start-up and load switching.
Summarize key advantages:
The core competitiveness of thick film low resistance resistors lies in their high cost-effectiveness in achieving high current carrying capacity, good structural strength, and reliability. It is an attractive solution for milliohm level resistor applications that require high power and harsh environments in large-scale production, such as current detection in power modules, motor drives, battery management systems, and automotive electronics. Although it may be slightly inferior to top metal foil resistors in terms of absolute accuracy and ultra-low TCR, its comprehensive performance, cost, and robustness make it the preferred technology in many application scenarios.