Technical data for resistance materials - KOUEI CO.,LTD.

Technical data for resistance materials

Volume resistivity and the highest service temperature for resistance materials

This is a distribution map of volume resistivity and the highest service temperature for typical resistance materials. Please reference this when you choose materials.

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Characteristic value of resistance materials

This is a characteristic value of typical resistance materials.

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Change of resistance by temperature.

Generally, electric resistance of materials changes along with temperature. Normally, resistance of metallic conductors increases along with rise of temperature. To the contrary, resistance decreases as for semiconductor, electrolyte, carbon, nonconductor and so on along with rise of temperature.

Temperature coefficient of resistance

“Temeperature coefficient of resitance at specific temperature” is expressed by an increased resistance value from specific temperature to certain increased temperature, and which is devided by the the resistance value at the increased temerature. From 20℃ to 200℃ the relationship between resistance value and temperature coefficient shows linearly change, so practically we can understand like the follwoing.

If the resistance value rises by every r 【Ω】 as the temperature rises every 1℃, the temperature coefficient α0 at 0℃, temperature coefficient α20 at 20℃ and temperature coefficient αt at t℃ are shown in formula below.

Resistance value of metallic conductor Rt at t℃ is calculated in formula below.

R₀:resistance value at 0℃ α₀:temperature coefficient at 0℃

Likewise, resistance value of metallic conductor Rt at 20℃ is calculated in formula below.

R₂₀:resistance value at 20℃ α₂₀:temperature coefficient at 20℃

Hence, this relationship between resistance value and temperature coefficient is formed below.

RT:resistance value at T℃ αt:temperature coefficient at t℃ Rt:resistance value at t℃

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Conductor resistance test

Conductor resistance test is performed according to JIS C2525. Standard temperature shall be 23℃. Conductor resistance whose dimension is out of specified dimension is calculated by calculation formula below, and rounded to three significant figures according to JIS Z 8401.

Rc=ρ/A

Rc: conductor resistance (Ω/m)
ρ: volume resistivity of Table1 (μΩ・m)
A: Cross-sectional area calculated by agreed dimensions between shipping and receiving parties. In case of strip, the value is calculated by the formula listed below and according to JIS Z 8401, rounded to four significant figures.

Width: less than 10mm thickness×width×0.96=cross-sectional area
Width: more than 10mm thickness×width×0.98=cross-sectional area

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