US3650860A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making printed circuits
Assignee: Bell and Howell Co
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Filing: 1968-08-22
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Granted: 1972-03-21
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Expires: 1988-08-22
Abstract
Abstract Printed circuits are made by a method which applies a dissoluble magnetizable layer to the electrically conductive coating of a circuit board blank. A magnetic image of the desired circuit is provided in the applied magnetizable layer and etchant-resistive magnetic toner is attracted by the magnetic image to form an etch resist pattern. The electrically conductive coating is then etched with the aid of an etchant and the latter etch resist pattern.
Inventors
- 👤 John H Rolker Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:31
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/061; H05K3/065; H05K2203/00; H05K2203/05; H05K2203/0502; H05K2203/052; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/901
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
25 words
A method as claimed in claim 1, wherein said magnetic toner is composed of a magnetizable substance and a material resisting attack by said etchant.
Claim 2
Dependent Claim
24 words
A method as claimed in claim 1, wherein said magnetic toner includes magnetizable particles having shells of a material resisting attack by said etchant.
Claim 3
Dependent Claim
26 words
A method as claimed in claim 1, wherein said magnetic image is provided by premagnetizing said magnetizable layer and selectively demagnetizing portions of said premagnetized layer.
Claim 4
Dependent Claim
33 words
A method as claimed in claim 4, wherein said portions of said premagnetized layer are demagnetized by heating said portions of said premagnetized layer to above the Curie temperature of said premagnetized layer.
Claim 5
Dependent Claim
23 words
A method as claimed in claim 1, wherein said magnetic image is provided by thermoremanent magnetization of selected portions of said magnetizable layer.
Claim 6
Dependent Claim
45 words
A method as claimed in claim 1, wherein said thermoremanent magnetization includes the steps of heating said selected portions of said magnetizable layer to above the Curie temperature of said magnetizable layer, and cooling said heated portions in the presence of an external magnetic field.
Claim 7
Dependent Claim
32 words
A method as claimed in claim 1, wherein said magnetic image is provided by preparing a master record of said magnetic image, and magnetically copying said master record on said magnetizable layer.
Claim 8
Dependent Claim
27 words
A method as claimed in claim 8, wherein said master record is copied on said magnetizable layer by thermoremanent magnetization in the presence of said master record.
Claim 9
Dependent Claim
37 words
A method as claimed in claim 9, wherein said thermoremanent magnetization includes the steps of heating said magnetizable layer to above its Curie temperature and cooling said heated magnetizable layer in the presence of said master record.
Claim 10
Dependent Claim
39 words
A method as claimed in claim 8, wherein said master record is copied on said magnetizable layer by the steps of providing anhysteretic transfer fields, and subjecting said magnetizable layer to said master record and said anhysteretic transfer fields.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-03-21 | 1975-09-20 | 1976-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-03-21 | 1979-09-20 | 1980-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-03-21 | 1983-09-20 | 1984-03-21 | $7700.00 | Window Closed / Lapsed |