US4661431A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of imaging resist patterns of high resolution on the surface of a conductor
Assignee: Hunt Imaging LLC
•
Filing: 1986-04-04
•
Granted: 1987-04-28
•
Expires: 2006-04-04
Abstract
Abstract An electrostatic latent image in a desired pattern is formed on an electrostatically imageable surface and toned with a liquid toner to form a toner image on the surface. The toner image is then transferred while still wet to a transfer sheet and then to the surface of a conductor, or the toner image may be transferred directly to the surface of a conductor without a transfer sheet, such direct transfer being preferred. The toner image is then fused to the conductor surface to provide an etch resist pattern of high resolution on the conductor surface. The conductor may then be etched to form a high density printed circuit. In the direct transfer method a nonpolar insulating solvent-carrier is applied to the surface of the conductor and the electrostatically imageable surface.
Inventors
- 👤 David P. Bujese
- 👤 Peter J. Calabrese
- 👤 Gary W. Schmidt
- 👤 Abelardo M. Santos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:04
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/061; H05K3/065; G; G03; G03G; G03G15/00; G03G15/06; G03G15/10; G03G15/14; G03G15/16; G03G15/1625; G03G15/22; G03G15/225; G03G15/65; G03G15/6582; G03G15/6585; H05K2203/00; H05K2203/05; H05K2203/0502; H05K2203/0517; H05K2203/0537; H05K3/10; H05K3/12; H05K3/1266
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
156 words
A method of fabricating a printed circuit board from a conductor laminate comprising the steps of: (a) forming an electrostatic latent image in a desired pattern on an electrostatically imageable surface; (b) toning the electrostatic latent image with a heat fusible liquid toner to form a toner image in the desired pattern on the electrostatically imageable surface; (c) transferring the toner image while still wet, in a first transfer step, from the electrostatically imageable surface to a dielectric transfer sheet; (d) transferring the toner image, in a second transfer step, from said transfer sheet to the conductor surface of a conductor laminate; (e) fusing the toner image to the conductor surface to form a pin-hole free, etch resistant toner image on the conductor surface; (f) etching non-image areas of the conductor to remove conductor from said non-image areas; and (g) removing toner from the image areas of the conductor surface to obtain a printed circuit board.
Claim 2
Independent Claim
156 words
A method of fabricating a printed circuit board from a conductor laminate comprising the steps of: (a) forming an electrostatic latent image in a desired pattern on an electrostatically imageable surface; (b) toning the electrostatic latent image with a heat fusible liquid toner to form a toner image in the desired pattern on the electrostatically imageable surface; (c) transferring the toner image while still wet, in a first transfer step, from the electrostatically imageable surface to a dielectric transfer sheet; (d) transferring the toner image, in a second transfer step, from said transfer sheet to the conductor surface of a conductor laminate; (e) fusing the toner image to the conductor surface to form a pin-hole free, etch resistant toner image on the conductor surface; (f) etching non-image areas of the conductor to remove conductor from said non-image areas; and (g) removing toner from the image areas of the conductor surface to obtain a printed circuit board.
Claim 3
Dependent Claim
58 words
The method of claim 1 wherein, during the second transfer step, an electric field is maintained between the conductor surface and the transfer sheet by applying a transfer potential in the form of a DC voltage to the conductor relative to a backing electrode said backing electrode being positioned adjacent the non-image bearing side of the transfer sheet.
Claim 4
Dependent Claim
27 words
The method of claim 2 further comprising the step of applying a film of nonpolar insulating solvent to the conductor surface prior to said second transfer step.
Claim 5
Dependent Claim
10 words
The method of claim 3 wherein the conductor is copper.
Claim 6
Dependent Claim
11 words
The method of claim 4 wherein the transfer sheet is plastic.
Claim 7
Dependent Claim
11 words
The method of claim 5 wherein the transfer sheet is flexible.
Claim 8
Dependent Claim
11 words
The method of claim 6 wherein the transfer sheet is polyester.
Claim 9
Dependent Claim
26 words
The method of claim 5 wherein the nonpolar insulating solvent applied to the conductor surface is a solvent-carrier that is also present in the liquid toner.
Claim 10
Dependent Claim
15 words
The method of claim 8 wherein the nonpolar insulating solvent is a branched aliphatic hydrocarbon.
Claim 11
Dependent Claim
23 words
The method of claim 5 wherein the second transfer step is initiated while the toner image on the transfer sheet is still wet.
Claim 12
Dependent Claim
19 words
The method of claim 5 wherein a transfer potential of about 500 to about 3500 volts DC is applied.
Claim 13
Dependent Claim
15 words
The method of claim 5 wherein pressure is 1 applied during the second transfer step.
Claim 14
Dependent Claim
26 words
The method of claim 1 wherein the toner image is permitted to dry in air on the conductor surface after step (d) and before step (e).
Claim 15
Dependent Claim
17 words
The method of claim 13 wherein the toner image is fused by applying heat to that image.
Claim 16
Dependent Claim
28 words
The method of claim 14 wherein the toner image is fused by heated it at about 40° C. to about 150° C. for about 15 to 30 seconds.
Claim 17
Dependent Claim
63 words
The method of claim 1 wherein the liquid toner comprises: (a) a nonpolar insulating solvent-carrier; (b) an alcohol insoluble maleic modified rosin ester; (c) a linear polyolefin; (d) an amphipathic polymer; (e) a copolymer of ethylene with a monomer selected from the group consisting of acrylic acid, the alkyl esters of acrylic acid, vinyl acetate and combinations thereof; and (f) a phthalocyanine pigment.
Claim 18
Independent Claim
164 words
A method of fabricating a printed circuit board from a conductor laminate comprising the steps of: (a) forming an electrostatic latent image in a desired pattern on an electrostatically imageable surface; (b) toning the electrostatic latent image with a heat fusible liquid toner to form a toner image in the desired pattern on the electrostatically imageable surface; (c) maintaining an electric field between the conductor surface and the electrostatically imageable surface; (d) placing the conductor surface in close proximity to the electrostatically imageable surface bearing the toner image to effect transfer of the toner image from the electrostatically imageable surface to the surface of the conductor; (e) fusing the toner image to the conductor surface of the conductor laminate to form a pin-hole free, etch resistant toner image on the conductor surface; (f) etching non-image areas of the conductor to remove conductor from said non-image areas; and (g) removing toner from the image areas of the conductor surface to obtain a printed circuit board.
Claim 19
Independent Claim
164 words
A method of fabricating a printed circuit board from a conductor laminate comprising the steps of: (a) forming an electrostatic latent image in a desired pattern on an electrostatically imageable surface; (b) toning the electrostatic latent image with a heat fusible liquid toner to form a toner image in the desired pattern on the electrostatically imageable surface; (c) maintaining an electric field between the conductor surface and the electrostatically imageable surface; (d) placing the conductor surface in close proximity to the electrostatically imageable surface bearing the toner image to effect transfer of the toner image from the electrostatically imageable surface to the surface of the conductor; (e) fusing the toner image to the conductor surface of the conductor laminate to form a pin-hole free, etch resistant toner image on the conductor surface; (f) etching non-image areas of the conductor to remove conductor from said non-image areas; and (g) removing toner from the image areas of the conductor surface to obtain a printed circuit board.
Claim 20
Dependent Claim
32 words
The method of claim 17 wherein the electric field is maintained by applying a charge to the conductor surface from a discharge corona positioned on the conductor side of the conductor laminate.
Claim 21
Dependent Claim
26 words
The method of claim 17 wherein the electric field is maintained by applying a transfer potential in the form of a DC voltage to the conductor.
Claim 22
Dependent Claim
18 words
The method of claim 19 wherein about 500 to about 3500 volts DC is applied to the conductor.
Claim 23
Dependent Claim
28 words
The method of claim 17 wherein the toner image is permitted to dry in air on the conductor surface after step (d) and before step (e) is conducted.
Claim 24
Dependent Claim
21 words
The method of claim 21 wherein the toner image is fused to the conductor surface by applying heat to the image.
Claim 25
Dependent Claim
29 words
The method of claim 22 wherein the toner image is fused by heating it at about 40° C. to about 150° C. for about 15 to about 20 seconds.
Claim 26
Dependent Claim
115 words
The method of claim 17 further comprising the steps of applying a water soluble polymer film to the conductor surface step (d), wherein said film is applied as a liquid coating that is dried before step (d), or as a dry film that is left dry prior to step (d), fusing the toner image to the dry polymer film and to the conductor surface in step (d) by applying heat to the image, rinsing the conductor surface with water after step (e) to remove the water soluble polymer film from non-image areas of the conductor surface, and removing the fused toner and polymer film from the image aras of the conductor surface during step (g).
Claim 27
Dependent Claim
13 words
The method of claim 24 wherein the water soluble polymer is polyvinyl acetate.
Claim 28
Dependent Claim
26 words
The method of claim 24 wherein the toner image is fused to the polymer film and to the conductor surface by applying heat to the image.
Claim 29
Dependent Claim
28 words
The method of claim 24 wherein the toner image is fused by heating at about 40° C. to about 210° C. for about 15 to about 30 seconds.
Claim 30
Dependent Claim
10 words
The method of claim 17 wherein the conductor is copper.
Claim 31
Independent Claim
207 words
A method of fabricating a printed circuit board from a conductor laminate comprising the steps of: (a) forming an electrostatic latent image in a desired pattern on an electrostatically imageable surface; (b) toning the electrostatic latent image with a heat fusible liquid toner which includes a nonpolar insulating solvent to form a toner image in the desired pattern on the electrostatically imageable surface; (c) applying a nonpolar insulating solvent to the conductor surface of the conductor laminate; (d) applying an electric field at a point of transfer between the conductor surface and the electrostatically imageable surface; (e) placing the conductor surface in close proximity to the electrostatically imageable surface bearing the toner image to effect transfer of the toner image from the electrostatically imageable surface to the conductor surface of the conductor laminate to create imaged areas and non-imaged areas on the conductor surface; (f) fusing the toner image to the conductor surface of the conductor laminate to form a pin-hole free, etch resistant toner image on the conductor surface; (g) etching the non-imaged areas of the conductor surface to remove conductor from the non-imaged areas; and (h) removing toner from the imaged areas of the conductor surface to expose a printed circuit pattern on the conductor.
Claim 32
Independent Claim
207 words
A method of fabricating a printed circuit board from a conductor laminate comprising the steps of: (a) forming an electrostatic latent image in a desired pattern on an electrostatically imageable surface; (b) toning the electrostatic latent image with a heat fusible liquid toner which includes a nonpolar insulating solvent to form a toner image in the desired pattern on the electrostatically imageable surface; (c) applying a nonpolar insulating solvent to the conductor surface of the conductor laminate; (d) applying an electric field at a point of transfer between the conductor surface and the electrostatically imageable surface; (e) placing the conductor surface in close proximity to the electrostatically imageable surface bearing the toner image to effect transfer of the toner image from the electrostatically imageable surface to the conductor surface of the conductor laminate to create imaged areas and non-imaged areas on the conductor surface; (f) fusing the toner image to the conductor surface of the conductor laminate to form a pin-hole free, etch resistant toner image on the conductor surface; (g) etching the non-imaged areas of the conductor surface to remove conductor from the non-imaged areas; and (h) removing toner from the imaged areas of the conductor surface to expose a printed circuit pattern on the conductor.
Claim 33
Dependent Claim
27 words
The method of claim 29 wherein the electric field is maintained at least partially by applying a charge to the conductor surface by a DC transfer corona.
Claim 34
Dependent Claim
20 words
The method of claim 30 wherein the DC transfer corona is positioned on the conductor side of the conductor laminate.
Claim 35
Dependent Claim
28 words
The method of claim 29 wherein the electric field is at least partially maintained by applying a transfer potential in the form of DC voltage to the conductor.
Claim 36
Dependent Claim
18 words
The method according to claim 32 wherein the transfer potential is about 500 to about 3500 volts DC.
Claim 37
Dependent Claim
23 words
The method according to claim 29 wherein the toner image is fused to the conductor surface by applying heat to the toner image.
Claim 38
Dependent Claim
12 words
The method according to claim 29 wherein the conductor surface is copper.
Claim 39
Dependent Claim
30 words
The method according to claim 29 wherein excess nonpolar insulating solvent is removed from the non-imaged areas while the imaged areas remain wet after step (e) and before step (f).
References Cited (Backward Citations)
US2910351A
Cited
US3071070A
Cited
US3075866A
Cited
US3650860A
Cited
US3856519A
Cited
US3758327A
Cited
JPS4838259A
Cited
US3862848A
Cited
US4373016A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-04-27 | 1990-10-27 | 1991-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-27 | 1994-10-27 | 1995-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-27 | 1998-10-27 | 1999-04-28 | $7700.00 | Window Closed / Lapsed |