What are the processing techniques for alloy resistors?

There are various processing techniques for resistors, and the core goal is to accurately form an alloy resistor layer with target resistance value, excellent temperature stability, low temperature coefficient, low noise, and high reliability on a specific substrate material. The main processes include:
 
 
1. Thin film process:
Vacuum deposition: In a high vacuum environment, alloy materials (such as nickel chromium alloys, tantalum nitrogen alloys, etc.) are deposited in atomic or molecular form on insulating substrates (such as ceramics, glass) through physical vapor deposition or chemical vapor deposition methods.
Lithography and etching: Coating photoresist on deposited thin films, exposing and developing them through photolithography masks to form a protective layer of the desired resistance pattern. Then use chemical etching or ion beam etching to remove the unprotected portion of the thin film, accurately forming a resistance pattern.
Laser tuning: Fine tune the etched resistance pattern with laser to precisely adjust the resistance value to the target resistance value (with an accuracy of ± 0.01% or higher). This is a crucial step in achieving high precision.
 
Features: High precision, low temperature coefficient, good stability, low noise. Suitable for manufacturing high-precision, small-sized, low-power resistors. The cost is relatively high.
 
2. Thick film process:
Screen printing: A resistor paste containing alloy powder (such as ruthenium oxide, palladium silver, etc. Strictly speaking, metal oxide paste is more commonly used for thick films, but alloy powder paste can also be used), glass powder, and organic carrier is accurately printed on a ceramic substrate through a screen template.
High temperature sintering: The printed substrate is sintered in a high-temperature furnace (usually 700-900 ° C). The organic carrier evaporates, and the glass powder melts to form a glass phase, firmly bonding the conductive phase (alloy particles) to the substrate and forming a conductive network.
 
Laser tuning: The resistance value after sintering has a certain range, and it is also necessary to achieve the target accuracy through laser tuning.
Features: The process is relatively simple, the cost is low, the power density is high, and it is suitable for manufacturing various resistance ranges. But the accuracy, temperature coefficient, and stability are usually slightly inferior to thin film resistors. Widely used in conventional surface mount resistors.
 
 
3. Metal foil process:
Alloy foil etching: bonding a thin foil (micrometer thickness) of a specific alloy (usually a nickel chromium based or copper nickel based modified alloy, such as Evans alloy) onto a ceramic substrate. Then, through photolithography and precision chemical etching processes, the foil material is etched into complex winding resistance patterns.
Characteristics: It has extremely low temperature coefficient, extremely high stability, extremely low noise, excellent pulse load capacity, and long-term stability. The accuracy is also very high. It is an ideal choice for high-performance and high reliability applications, such as precision instruments, medical equipment, and aerospace. The highest cost.
 
 
4. Winding process:
Winding: Thin alloy resistance wires (such as manganese copper, constantan, nickel chromium alloy, etc.) are wound onto an insulating skeleton (ceramic, plastic) or precisely wound onto a substrate.
Encapsulation: To protect the wound resistor, commonly used materials include glaze, epoxy resin, silicone, or metal casing.
 
Features: High power, good stability, low noise, and can withstand high pulses. However, due to its relatively large size and the presence of parasitic inductance and capacitance, it is not suitable for high-frequency circuits. Mainly used in high-power and high-precision applications.
 
5. Metal ceramic body technology:
Mixed pressing and sintering: Metal oxide powder (such as ruthenium oxide) is mixed with ceramic powder (such as alumina), pressed into shape, and then sintered into a solid resistor at high temperature. Both ends are covered with electrodes.
Features: Located between thick film and wire winding, it has good pulse load capacity, high power density, and good stability. Commonly used for power resistors.
 
 
 
6. Metal strip/stamping process:
Stamping forming: Using a stamping die to press alloy sheets (such as manganese copper and constantan) into specific resistance shapes (such as sheet or strip).
Welding leads/terminals: Welding leads or directly forming them into terminals on a stamped resistor body.
Encapsulation: Perform protective encapsulation (such as molded plastic, painted).
Features: Mainly used for high current detection resistors (current sampling resistors, splitters). Require extremely low resistance (milliohm level) and good temperature stability.
 
 
Key common process steps:
 
 
 
Base preparation: Clean and process ceramic substrates or other insulating substrates.