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Tuesday, January 10, 2017
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The best materials to construct a thick film power resistor
In thick film power electrical device style material choice is important to confirm the electrical device will each dissipate the specified quantity of warmth and retain a stable resistance over time.
Important problems to think about in thick film electrical device style include:
• electrical device tolerance
• Temperature constant of resistance
• Resistance drift
• Power rating
Often the ability rating and resistance drift area unit the foremost necessary however all area unit associated with the suitable alternative of materials. as an example the ability rating and temperature constant of resistance area unit mostly obsessed on the selection of substrate material. Whereas resistance drift is additional associated with the electrical device paste and process.
No single substrate material is a perfect alternative that satisfies all the necessary properties of thick film substrates. the selection of substrate material is thus typically associated with the electrical, thermal and mechanical demands of the applying. a perfect thick film substrate ought to have:
• Low nonconductor constant
• smart dimensional stability throughout process
• smart adhesion between substrate and written materials
• High thermal conduction
• A thermal constant of enlargement matching different materials within the circuit
• High electrical electric resistance
Alumina may be a common alternative that satisfies the bulk of the on top of necessities in most applications but it's brittle and might snap (especially with massive substrates), shaping may typically be a problem. For terribly high power dissipation aluminum chemical compound is usually used because it has 5 times the thermal conduction of aluminum oxide however it's comparatively dear and needs the utilization of special printing pastes and process.
With the substrate material established the electrical device material ought to be outlined. electrical device materials area unit applied in paste kind by screen printing and area unit then dismissed by heating to a extreme temperature. electrical device pastes have 3 main ingredients:
• The practical components (metal alloy or compound particles)
• Binder (glass particles)
• Organic solvents and temporary binder
The temporary binders offer management over the printing. They evaporate early within the firing method along side the solvents. The glass particles soften within the firing method, bind the active particles along, adhere to the substrate and supply stability to the circuit.
Important problems to think about in thick film electrical device style include:
• electrical device tolerance
• Temperature constant of resistance
• Resistance drift
• Power rating
Often the ability rating and resistance drift area unit the foremost necessary however all area unit associated with the suitable alternative of materials. as an example the ability rating and temperature constant of resistance area unit mostly obsessed on the selection of substrate material. Whereas resistance drift is additional associated with the electrical device paste and process.
No single substrate material is a perfect alternative that satisfies all the necessary properties of thick film substrates. the selection of substrate material is thus typically associated with the electrical, thermal and mechanical demands of the applying. a perfect thick film substrate ought to have:
• Low nonconductor constant
• smart dimensional stability throughout process
• smart adhesion between substrate and written materials
• High thermal conduction
• A thermal constant of enlargement matching different materials within the circuit
• High electrical electric resistance
Alumina may be a common alternative that satisfies the bulk of the on top of necessities in most applications but it's brittle and might snap (especially with massive substrates), shaping may typically be a problem. For terribly high power dissipation aluminum chemical compound is usually used because it has 5 times the thermal conduction of aluminum oxide however it's comparatively dear and needs the utilization of special printing pastes and process.
With the substrate material established the electrical device material ought to be outlined. electrical device materials area unit applied in paste kind by screen printing and area unit then dismissed by heating to a extreme temperature. electrical device pastes have 3 main ingredients:
• The practical components (metal alloy or compound particles)
• Binder (glass particles)
• Organic solvents and temporary binder
The temporary binders offer management over the printing. They evaporate early within the firing method along side the solvents. The glass particles soften within the firing method, bind the active particles along, adhere to the substrate and supply stability to the circuit.
