Standards and production processes of precision resistors
In the field of electronic devices, high-precision resistors occupy a vital position, especially in applications that require extremely high precision. The definition of high-precision resistors is based on the size of their resistance error. Specifically, when the resistance of the resistor is greater than 1Ω, if the resistance error can be controlled within ±0.5%, it can be called a precision resistor. The accuracy of more advanced precision resistors can reach an astonishing 0.01%. This level of accuracy is usually described by electronic engineers as an accuracy of one ten thousandth, and represents the top level of resistor manufacturing technology. This type of high-precision resistors are mostly manufactured using thin-film technology, because only thin-film resistors can meet such high-standard production process requirements. In contrast, the accuracy of ordinary series of resistors above 1Ω is generally above ±5%, which is the most common accuracy category in electronic products, but does not belong to the category of high-precision resistors.
For resistors below 1Ω, a precision of ±1% can already be classified into the ranks of high-precision resistors. Considering the small base of the resistance value, even a 1% error will have a relatively small actual impact. Further improving the accuracy to ±0.5% puts forward higher requirements for production processes and technologies, reflecting technological progress in material selection, fine processing, etc.
Types and selection of high-precision resistors
High-precision resistors can be divided into two categories: plug-in type and chip type according to the installation method. Chip type resistors are widely used because of their high precision, low temperature coefficient (low temperature drift), small size and suitability for automated production. All kinds of high-end electronic products. In addition, according to materials, precision resistors can also be divided into three types: metal film, wirewound and metal foil. Metal film precision resistors are known for their high accuracy, but are slightly deficient in resistance temperature coefficient and distribution parameters; wire-wound precision resistors are excellent in resistance accuracy and temperature coefficient, but their distribution parameters are low; Metal foil precision resistors have excellent performance in terms of accuracy, temperature coefficient of resistance and distribution parameters, and are the embodiment of precision, performance and technological integration.
In applications, choosing the appropriate type of precision resistor needs to be based on actual needs and cost considerations. For example, in DC or low-frequency AC circuits, wirewound or metal film precision resistors can meet most needs, eliminating the need for higher-cost metal foil precision resistors. It is worth noting that precision resistors of different shapes also show their own characteristics during installation and use. For example, wire-wound precision resistors use a non-inductive winding method to reduce distributed inductance, while precision resistors of specific shapes such as rectangular frame shapes Wirewound resistors, often customized to the requirements of specific equipment, are used to meet the precise measurement needs of special applications.
Maintenance and replacement of high-precision resistors
In practical applications, the maintenance and replacement of high-precision resistors is the key to ensuring the stable operation of electronic equipment. When a precision resistor of a specific shape (such as a rectangular frame-shaped wire-wound precision resistor) in an instrument is damaged, a new alloy resistance wire of the same material, diameter and length as the original resistor can be selected and wound evenly according to the original frame. Make a substitution. If the surface insulation layer of the resistor is damaged, its function can be restored by disassembling the original resistance wire, re-dipping it in paint and drying it, and then winding it onto the original frame again. These maintenance and replacement operations require operators not only to have professional electronic knowledge, but also to have certain manual skills to ensure that the replaced resistor can meet the same performance standards as the original resistor.