Copper/Tungsten vs.Copper Flange Construction
■Barry Industries set out to compare the two different construction methods of their Flanged and leaded Resistors. Construction “A” consists of a Copper/Tungsten (Cu/W) flange with Gold/Germanium (Au/Ge) preforms and .060” thick BeO, 270-ohm chip resistor with leads. Construction “B” consists of a Copper (Cu) flange with Lead/Silver preforms and .060” thick BeO, 270-ohm chip resistor with leads. Four resistors of each type construction were cycled for a period of 9 seconds on and 9 seconds off.Each resistor had 150 Watts of applied power for the 9 second on cycle.
●Conclusion:
■While Resistors built on Copper flanges may be good for CW power applications, they do not survive in applications where the power is constantly being cycled. The main reason for this is the disparity in the Thermal Coefficient of Expansion (TCE) between the Copper flange and the substrate material. The construction “B” type resistors are not recommended for Pulsed Power Applications.
■The Resistors built on Copper/tungsten flanges have a TCE that is matched to that of the BeO Substrate. This matching forms a bond that moves in unison as the Assembly is heated and cooled by the applied power. The Construction ” A” samples are greatlySuperior when the application requires the power to be pulsed or cycled.The Copper/Tungsten flanged resistors lasted an average of 150 Times longer.
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Flanged and leaded Resistors 、 Copper/Tungsten flanged resistors |
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Application note & Design Guide |
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Please see the document for details |
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English Chinese Chinese and English Japanese |
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November 17, 2005 |
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Revision:A |
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BTR-030 |
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208 KB |
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