EP0036247A2
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EP
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A thin film resistance thermometer element and its method of manufacture
Assignee: Leeds and Northrup Co
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Filing: 1981-02-16
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Granted: —
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Expires: 2001-02-16
Abstract
Abstract The resistance thermometer element is made by forming a serpentine pattern 16,18,20 of a thin film of a metal such as platinum deposited on a substrate 10. The deposited metal has a bulk temperature coefficient of resistance (TCR) substantially greaterthan the desired TCR which is established by controlling the thickness of the film to the correct value in a range of thicknesses where TCR changes relatively rapidly with thickness, eg the range 0.05 to 0.8 microns for platinum. The required thickness may be established by deposition at a control rate for a controlled time or by over deposition followed by reduction in thickness by etching. The calibration resistance at the ice point is then independently established by selective removal of shorting links in parts 22, 24, 26, 28 of the pattern.
Inventors
- 👤 Ronald Dale Baxter
- 👤 Paul Justus Freud
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 20:54
CPC Classifications
H; H01; H01C; H01C7/00; H01C7/02; H01C7/021; G; G01; G01K; G01K7/00; G01K7/16; G01K7/18; G01K7/183; H01C17/00; H01C17/22; H01C17/232
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
67 words
1 . A method of making a thin film resistance thermometer element with a predetermined TCR by depositing the film on an electrically insulating substrate, characterised in that the film is produced as a deposit of a metal whose bulk TCR is substantially higher than the predetermined TCR and the thickness of film is controlled to a value at which the TCR is at the predetermined value.
Claim 2
Dependent Claim
67 words
1 . A method of making a thin film resistance thermometer element with a predetermined TCR by depositing the film on an electrically insulating substrate, characterised in that the film is produced as a deposit of a metal whose bulk TCR is substantially higher than the predetermined TCR and the thickness of film is controlled to a value at which the TCR is at the predetermined value.
Claim 3
Dependent Claim
36 words
A method according to claim 1, characterised in that the film is deposited to a thickness exceeding that necessary to obtain the predetermined TCR and is then reduced to that value which gives the predetermined TCR.
Claim 4
Dependent Claim
19 words
A method according to claim 2, characterised in that the film thickness is reduced by ion beam sputter etching.
Claim 5
Dependent Claim
17 words
A method according to claim 2, characterised in that the film thickness is reduced by chemical etching.
Claim 6
Dependent Claim
24 words
A method according to claim 1, characterised in that the film thickness is built up by successive depositions until the predetermined TCR is obtained.
Claim 7
Independent Claim
30 words
A method according to any of claims 1 to 5, characterised in that the film is platinum and the thickness is controlled to the range between 0.05 and 0.8 microns.
Claim 8
Independent Claim
41 words
A method according to any of claims 1 to 5, characterised in that the film is platinum and the thickness is small enough for the ratio of relative change of TCR to relative change of thickness to be greater than 0.01.
Claim 9
Independent Claim
38 words
A method according to any of claims 1 to 5, characterised in that the film is platinum and the thickness is small enough for the TCR to be at least 1% below the film bulk value of TCR.
Claim 10
Independent Claim
27 words
A method according to any of claims 1 to 5, characterised in that the thickness exceeds the thickness at which nucleation in the film affects its conductivity.
Claim 11
Independent Claim
46 words
A method according to any of claims 1 to 9, characterised in that the film has a serpentine pattern with shorting links and in that selected shorting links are out to provide a predetermined resistance at 0 0 C after the predetermined TCR has been established.
Claim 12
Dependent Claim
82 words
A resistance thermometer element comprising an electrically insulating substrate and a think platinum film with a predetermined TCR deposited on the substrate in a pattern to produce a predetermined ice point resistance, characterised in that the thickness of the film is such as to produce the predetermined TCR and is substantially below the thickness at which the TCR is at its bulk value but substantially above the thickness at which nucleation effects predominate in determining the conductivity and TCR of the film.
Claim 13
Dependent Claim
82 words
A resistance thermometer element comprising an electrically insulating substrate and a think platinum film with a predetermined TCR deposited on the substrate in a pattern to produce a predetermined ice point resistance, characterised in that the thickness of the film is such as to produce the predetermined TCR and is substantially below the thickness at which the TCR is at its bulk value but substantially above the thickness at which nucleation effects predominate in determining the conductivity and TCR of the film.
Claim 14
Dependent Claim
20 words
A resistance thermometer element according to claim 11, characterised in that the film thickness is between 0.05 and 0.8 microns.
Claim 15
Dependent Claim
30 words
A resistance thermometer element according to claim 11 or 12, characterised in that the ratio of relative change of TCR to relative change in film thickness is greater than 0.01.
References Cited (Backward Citations)
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