US3635802A
Expired / Lapsed
US
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Method of anodizing a thin-film device
Assignee: AT&T Inc
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Filing: 1970-11-06
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Granted: 1972-01-18
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Expires: 1990-11-06
Abstract
Abstract Thin-film resistors and other devices are precision adjusted by a regular, geometric progression of steps. Each step of a binary step anodization pattern for adjusting a resistor to a nominal resistance value is designed to decrease by one-half the percentage deviation in resistance from the nominal value at the end of the preceding step. Successive binary step decreases in the percentage resistance deviation are attained by a series of binary step decreases in the product of anodizing current and anodizing time for each step. The resultant, decreasing rate adjustment pattern tends to render negligible any chance of substantially overshooting the desired nominal value while permitting rapid attainment of the nominal value. A general purpose, process control computer is equipped with a series of tapes or other program devices storing anodizing current and anodizing time information for carrying out successive steps of the subject anodizing technique. Such information is that which has been derived for given sets of conditions and resistor codes, incorporating various regular, geometric progression anodizing patterns and linear approximations, such as a linear approximation of a binary step pattern. Each resistor is anodized in successive steps, after each of which steps a resistance measurement is made and the anodizing current and anodizing time for the next step are determined. Anodization is terminated when the tolerance zone about the nominal resistance value is entered.
Inventors
- 👤 Robert A Manning
- 👤 Donald H Raymond
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:16
CPC Classifications
H; H01; H01C; H01C17/00; H01C17/22; H01C17/26; H01C17/262; C; C25; C25D; C25D11/00; C25D11/02; G; G05; G05F; G05F1/00; G05F1/10; H10; H10N; H10N97/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
20 words
A method of anodizing a thin-film device as set forth in claim 1, wherein said fixed fractional multiple is one-half.
Claim 2
Dependent Claim
46 words
A method of anodizing a thin-film device as set forth in claim 1, wherein the product of anodizing current and anodizing time for each succeeding step is selected as said fixed fractional multiple times the product of anodizing current and anodizing time for the preceding step.
Claim 3
Dependent Claim
20 words
A method of anodizing a thin-film device as set forth in claim 3, wherein said fixed fractional multiple is one-half.
Claim 4
Dependent Claim
85 words
In a method of anodizing a thin-film device, the steps of: applying to the thin-film device in the presence of an electrolyte a first anodizing current for A first time period selected to provide a first current-time product; and then applying to the thin-film device in the presence of said electrolyte a second anodizing current for a second time period, the second anodizing current and the second time period selected to provide a second current-time product substantially equal to one-half of said first current-time product.
Claim 5
Dependent Claim
111 words
In a method of anodizing a thin-film device: anodizing the device by performing at least three steps substantially according to a pattern of steps InTn K nI0T0, where n is the number of each step, In is the anodizing current applied to the device in the presence of an electrolyte during each step n, Tn is the time for which the anodizing current In is applied during each step n, K is a constant greater than 1, I0 is the anodizing current applied to the device during an initial step corresponding to n 0, and T0 is the time for which the anodizing current I0 is applied during said initial step.
Claim 6
Dependent Claim
17 words
In a method of anodizing a thin-film device as set forth in claim 6, where K 2.
Claim 7
Dependent Claim
115 words
In a method of anodizing a thin-film device: anodizing the device by performing at least three steps according to a linear approximation of the nonlinear pattern of steps InTn K nI0T0, where n is the number of each step, In is the anodizing current applied to the device in the presence of an electrolyte during each step n, Tn is the time for which the anodizing current In is applied during each step n, K is a constant greater than 1, I0 is the anodizing current applied to the device during an initial step corresponding to n 0, and T0 is the time for which the anodizing current i0 is applied during said initial step.
Claim 8
Dependent Claim
17 words
In a method of anodizing a thin-film device as set forth in claim 8, where K 2.
Claim 9
Dependent Claim
140 words
In a method of anodizing a thin-film device, the steps of: applying to the thin-film device in the presence of an electrolyte a first anodizing current for a first time period, the first anodizing current and the first time period selected to provide a first current-time product; then applying to the thin-film device in the presence of said electrolyte a second anodizing current for a second time period, the second anodizing current and the second time period selected to provide a second current-time product substantially equal to a predetermined percentage of the first current-time product; and then applying to the thin-film device in the presence of said electrolyte for a third time period, the third anodizing current and the third time period selected to provide a third current-time product substantially equal to said predetermined percentage of the second current-time product.
Claim 10
Dependent Claim
20 words
In a method of anodizing a thin-film device, as set forth in claim 10, said predetermined percentage being 50 percent.
Claim 11
Dependent Claim
32 words
In a method of anodizing a thin-film device as set forth in claim 10, at least one of said steps comprising varying the anodizing current from that employed during a preceding step.
Claim 12
Dependent Claim
32 words
In a method of anodizing a thin-film device as set forth in claim 10, at least one of said steps comprising varying the time period from that employed during a preceding step.
Claim 13
Dependent Claim
134 words
In a method of anodizing a thin-film device, as set forth in claim 10, to bring a parameter of the thin-film circuit within a tolerance range of a desired final value of the parameter: performing a plurality of steps each comprising applying to the thin-film device in the presence of said electrolyte an anodizing current for a time period such that the current-time product for each succeeding step is substantially said predetermined percentage Of the current-time product for the preceding step until the parameter falls within the tolerance range of the desired final value of the parameter, at least one of said steps comprising varying the anodizing current from that employed during a preceding step and at least one of said steps comprising varying the time period from that employed during a preceding step.
Claim 14
Dependent Claim
87 words
In a method of anodizing a thin-film device as set forth in claim 10: first performing a plurality of steps each comprising applying to the thin-film device in the presence of said electrolyte a constant anodizing current for time periods varying substantially in geometric progression according to said predetermined percentage; and then performing a plurality of steps each comprising applying to the thin-film device in the presence of said electrolyte for a constant time period anodizing currents varying substantially in geometric progression according to said predetermined percentage.
References Cited (Backward Citations)
US2920018A
Cited
US3520783A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |