Introduction to the electrical properties of hardware metal

In the field of electronic components, it is inevitable to deal with hardware, whether you are purchasing or technology, handy metal knowledge or let you know a lot at work, and can also avoid detours at work. The hardware is commonly used as a tool obtained by processing gold, silver, copper, iron, tin and other metals, and its purpose is to fix, process, and decorate. Gold and silver are precious metals, mostly used for making jewelry, currency, etc.; as the messenger of human civilization, copper has strong conductivity and low price, and is the best choice for wires; iron is one of the most abundant metals in the world and is widely used In the electrical industry; there are also metals such as tin and nickel that are mostly used in the plating of small objects. The electrical performance of metal is an important criterion for material selection.

1. Conductivity

The ability of an object to conduct electrical current is called conductivity. The conductivity of metals is limited by objective factors such as temperature and humidity. The order of resistivity at 20°C from small to large is: silver, copper, gold, aluminum, tungsten, zinc, nickel, tin, iron, lead. At this temperature, the performance of the metal wire is the best silver, and it decreases sequentially. Good conductive properties play an important role in hardware. Usually, copper with strong conductive properties is selected as the material of the conductive parts, which has small resistivity and high cost performance.

Metal thermal conductivity is measured by thermal conductivity. Thermal conductivity refers to the 1m thick material under stable heat transfer conditions, the temperature difference between the two sides of the surface is 1 degree (K, ℃), within 1 second (1S), the heat transferred through an area of ​​1 square meter, the unit is Watt/meter·degree (W/(m·K), here K can be replaced by ℃). Different materials have different thermal conductivity. The thermal conductivity of the same substance is related to its structure, density, humidity, temperature, pressure and other factors. When the moisture content of the same substance is low and the temperature is low, the thermal conductivity is small. In general, the thermal conductivity of solids is greater than that of liquids, and that of liquids is greater than that of gases. The thermal conductivity of metals is arranged from large to small: silver, copper, gold, aluminum, sodium, molybdenum, tungsten, zinc, nickel, iron, platinum, tin, lead.

3. Hardness and ductility

Hardness is an important performance indicator to measure the degree of softness and hardness of metal materials. It can be understood as the ability of a material to resist elastic deformation, plastic deformation or destruction, or it can be expressed as the ability of a material to resist residual deformation and anti-destruction. Hardness is not a simple physical concept, but a comprehensive indicator of mechanical properties such as material elasticity, plasticity, strength and toughness. Hardness test can be divided into static pressure method (such as Brinell hardness, Rockwell hardness, Vickers hardness, etc.), scratch method (such as Mohs hardness), rebound method (such as Shore hardness) and Various methods such as micro hardness and high temperature hardness. For alloys, the hardness of different composition ratios is also different. The common hardness of common metals is iron>silver>gold>aluminum>lead. Harder metals are less ductile, while softer metals are more ductile and resilient.

4. Corrosion resistance

The ability of metal materials to resist the corrosion and destruction of the surrounding medium is called corrosion resistance. It is determined by the composition, chemical properties, and morphology of the material. Adding chromium, nickel, aluminum, and titanium that can form a protective film to steel; copper that changes electrode potential, and titanium and niobium that improve intergranular corrosion can improve corrosion resistance. Adding chromium to steel will make the surface very bright. Avoid hexavalent chromium. It is generally used as a coating for exposed metal parts. It is very beautiful; adding nickel to prevent corrosion. It is generally used as a percentage with chromium; or zinc.

The shell material of the connector and the metal hardware used for the contacts play an important role in the performance of the entire connector. The connector usually uses a brass chrome-plated shell, nickel-plated internal metal parts on the copper alloy surface, and copper alloy surface The gold-plated needle core can not only ensure the stability of the conductive parts, but also have a beautiful and durable appearance.

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