US6316289B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming fine-pitch interconnections employing a standoff mask
Assignee: Amerasia International Technology Inc
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Filing: 1999-03-25
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Granted: 2001-11-13
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Expires: 2019-03-25
Abstract
Abstract In the construction of electronic devices with one or more flip chips and, in some cases, one or more leadless components, mounted on a substrate, the interconnections are made with conductive adhesive or solder paste deposited using specialized stencils or masks, including suitable snap-back stencils and direct-contact masks without snap back. A metal stencil (or mask) is placed temporarily onto the face of a substrate, such as a semiconductor wafer, circuit board or other substrate, and is spaced apart therefrom by standoff features. When the stencil is properly positioned with respect to the wafer or substrate, as by relational alignment holes or optical alignment methods, conductive adhesive material is deposited onto the substrate through holes or openings in the stencil. The metal stencil includes on the side thereof facing the substrate a flexible standoff layer having standoff features to space the stencil apart from the substrate. The flexible standoff features are spaced away from the openings of the stencil so as to facilitate the forming of fine features of the conductive paste that have a height that is substantially greater than the thickness of the metal stencil, while avoiding smearing of the conductive adhesive paste and avoiding the conductive adhesive paste adhering to the openings of the stencil rather than to the substrate. Standoff features are formed by depositing suitable adhesive or metal materials or by etching the metal stencil. Openings in the metal stencil are formed by suitable means such as laser cutting, electroforming or photo-etching. The stencil may be fabricated of a membrane of magnetic material and be held in place by the magnetic forces produced by an electromagnet included in the assembly tooling.
Inventors
- 👤 Kevin Kwong-Tai Chung
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:03
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/10; H05K3/12; H05K3/1216; H05K3/1225; H10; H10W; H10W70/00; H10W70/01; H10W70/05; H10W70/098; B; B41; B41M; B41M3/00; H10W72/00; H10W72/01; H10W72/012; H10W72/01204; H10W72/20; H10W72/221; H10W72/225; H10W72/251; H10W72/253; H10W72/90; H10W72/921; H10W72/923; H10W72/941; H10W72/9415; H10W72/951; H10W72/952
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
177 words
A method for forming a pattern of adhesive on a substrate, the pattern of adhesive having a height greater than a given height, comprising: obtaining a substrate having a pattern of sites thereon on which adhesive is to be deposited; obtaining a standoff mask including a metal sheet of thickness substantially the given height having a pattern of openings corresponding to the pattern of sites and having standoff features thereon, wherein the standoff features are spaced away laterally from the openings and with said metal sheet define a thickness greater than the given height; positioning said substrate and said standoff mask proximate each other with the standoff features proximate the substrate so that the pattern of sites and the pattern of openings correspond; applying adhesive to substantially fill and pass through the openings of said standoff mask and to contact the sites on the substrate; and removing said standoff mask to leave said adhesive on said pattern of sites, whereby a pattern of adhesive having a height greater than the given height is formed on the substrate.
Claim 2
Independent Claim
177 words
A method for forming a pattern of adhesive on a substrate, the pattern of adhesive having a height greater than a given height, comprising: obtaining a substrate having a pattern of sites thereon on which adhesive is to be deposited; obtaining a standoff mask including a metal sheet of thickness substantially the given height having a pattern of openings corresponding to the pattern of sites and having standoff features thereon, wherein the standoff features are spaced away laterally from the openings and with said metal sheet define a thickness greater than the given height; positioning said substrate and said standoff mask proximate each other with the standoff features proximate the substrate so that the pattern of sites and the pattern of openings correspond; applying adhesive to substantially fill and pass through the openings of said standoff mask and to contact the sites on the substrate; and removing said standoff mask to leave said adhesive on said pattern of sites, whereby a pattern of adhesive having a height greater than the given height is formed on the substrate.
Claim 3
Dependent Claim
45 words
The method of claim 1 wherein said obtaining a standoff mask includes obtaining a sheet of metal, forming the pattern of openings therein, and forming the standoff features on at least one surface of said sheet of metal and spaced away from the openings therein.
Claim 4
Dependent Claim
34 words
The method of claim 2 wherein said metal is selected from the group including steel, carbon steel, stainless steel, magnetic stainless steel, nickel alloy, iron alloy, molybdenum, titanium and alloys, combinations and laminations thereof.
Claim 5
Dependent Claim
24 words
The method of claim 2 wherein said forming the pattern of openings includes at least one of photo-etching, laser machining, electroforming, and die cutting.
Claim 6
Dependent Claim
45 words
The method of claim 2 wherein said forming the standoff features includes forming a layer of flexible material having a surface energy of less than about 50 dyne/cm on at least one surface of said sheet of metal and spaced away from the openings therein.
Claim 7
Dependent Claim
45 words
The method of claim 2 further including forming a layer of flexible material having a surface energy of less than about 50 dyne/cm on a second surface of said sheet of metal and having openings therein corresponding to the openings in the sheet of metal.
Claim 8
Dependent Claim
85 words
The method of claim 1 wherein said obtaining a standoff mask includes obtaining a sheet of metal having first and second opposing surfaces, forming at least one cavity in the first surface of said sheet of metal to define the standoff features on at least the first surface thereof spaced away from locations at which the openings of the pattern of openings are formed, and forming the pattern of openings between the second surface and the at least one cavity of the sheet of metal.
Claim 9
Dependent Claim
82 words
The method of claim 1 wherein said obtaining a standoff mask includes obtaining a sheet of metal having first and second opposing surfaces, forming the pattern of openings between the first and second surfaces of the sheet of metal and forming standoff features on at least the first surface thereof spaced away from locations at which the openings of the pattern of openings are formed, wherein the standoff features are formed by selectively electroplating, selectively electroforming or selectively electro-depositing the same metal.
Claim 10
Dependent Claim
38 words
The method of claim 1 wherein obtaining a substrate includes obtaining a semiconductor wafer having a plurality of electrical circuits formed therein, each of said electrical circuits having contact pads that are included in said pattern of sites.
Claim 11
Dependent Claim
40 words
The method of claim 1 wherein obtaining a substrate includes obtaining a printed wiring circuit board having an electrical circuit wiring pattern thereon, wherein said electrical circuit wiring pattern includes contact pads that are included in said pattern of sites.
Claim 12
Dependent Claim
77 words
The method of claim 1 wherein positioning said substrate and said standoff mask includes aligning at least two relational alignment holes on said standoff mask with two corresponding relational alignment holes on said substrate, the relational alignment holes of said standoff mask being in known predetermined position with respect to said pattern of openings and the corresponding relational alignment holes of said substrate being in the same known predetermined position with respect to said pattern of sites.
Claim 13
Dependent Claim
36 words
The method of claim 11 wherein said aligning at least two relational alignment holes includes inserting respective alignment pins through each respective aligned pair of corresponding relational alignment holes of said standoff mask and said substrate.
Claim 14
Dependent Claim
43 words
The method of claim 1 wherein positioning said substrate and said standoff mask includes one of positioning said standoff mask against said substrate for use as a mask and positioning said standoff mask spaced apart from said substrate for use as a stencil.
Claim 15
Dependent Claim
34 words
The method of claim 1 wherein positioning said substrate and said standoff mask includes positioning said standoff mask spaced apart from said substrate and tensioning said standoff mask for use as a snap-back stencil.
Claim 16
Dependent Claim
14 words
The method of claim 1 wherein said applying adhesive includes applying a solder paste.
Claim 17
Dependent Claim
25 words
The method of claim 1 wherein said applying adhesive includes applying a flexible polymer adhesive selected from the group including thermoplastic resin and thermosetting resin.
Claim 18
Dependent Claim
28 words
The method of claim 1 wherein said applying adhesive includes applying a flexible polymer adhesive filled with sufficient electrically-conductive particles to render the flexible polymer adhesive electrically conductive.
Claim 19
Dependent Claim
29 words
The method of claim 17 wherein said electrically-conductive particles are selected from the group including gold, silver, platinum, palladium and alloys thereof and coatings thereof on a base material.
Claim 20
Dependent Claim
46 words
The method of claim 1 further comprising attaching said substrate to a device substrate having a pattern of sites thereon corresponding to the pattern of sites on said substrate, wherein corresponding sites of the respective patterns of sites are aligned and are joined by said adhesive.
Claim 21
Dependent Claim
18 words
The method of claim 19 wherein said attaching said substrate includes heating said substrate and said device substrate.
Claim 22
Dependent Claim
19 words
The method of claim 19 wherein said attaching said substrate includes pressing said substrate and said device substrate together.
Claim 23
Dependent Claim
72 words
The method of claim 1 wherein said obtaining a standoff mask includes obtaining a sheet of metal having the pattern of openings therein, forming a layer of flexible material on at least one surface of said sheet of metal material, and forming openings in said layer of flexible material that are substantially larger than corresponding ones of the openings in said sheet of metal so as to be spaced away laterally therefrom.
Claim 24
Dependent Claim
32 words
The method of claim 22 wherein said forming openings in said layer of flexible material includes forming openings that include a plurality of ones of the openings in said sheet of metal.
Claim 25
Dependent Claim
25 words
The method of claim 1 wherein at least ones of the sites of said pattern of sites have a pitch of less than 200 microns.
Claim 26
Dependent Claim
20 words
The method of claim 1 wherein at least one of said openings has a dimension of less than 300 microns.
Claim 27
Dependent Claim
20 words
The method of claim 1 wherein at least one of said openings has a dimension of less than 100 microns.
Claim 28
Dependent Claim
12 words
An electronic device made according to the method of claim 1 .
Claim 29
Dependent Claim
12 words
An electronic device made according to the method of claim 19 .
Claim 30
Dependent Claim
110 words
A standoff mask comprising a metal membrane of thickness substantially a given dimension having a pattern of openings therethrough and a patterned layer of flexible material on at least one side of said metal membrane, said patterned layer having a pattern of openings therethrough corresponding to the pattern of openings in said metal membrane, wherein said flexible material is spaced away laterally from at least one of the openings in said metal membrane, and wherein said metal membrane with said patterned layer defines a thickness greater than the given dimension, whereby material deposited through the pattern of openings of said metal membrane has a height greater than the given dimension.
Claim 31
Dependent Claim
110 words
A standoff mask comprising a metal membrane of thickness substantially a given dimension having a pattern of openings therethrough and a patterned layer of flexible material on at least one side of said metal membrane, said patterned layer having a pattern of openings therethrough corresponding to the pattern of openings in said metal membrane, wherein said flexible material is spaced away laterally from at least one of the openings in said metal membrane, and wherein said metal membrane with said patterned layer defines a thickness greater than the given dimension, whereby material deposited through the pattern of openings of said metal membrane has a height greater than the given dimension.
Claim 32
Dependent Claim
24 words
The standoff mask of claim 29 wherein said flexible material is a flexible polymer adhesive having a surface energy less than about 50 dyne/cm.
Claim 33
Dependent Claim
40 words
The standoff mask of claim 29 wherein said metal membrane is formed of a metal selected from the group including steel, carbon steel, stainless steel, magnetic stainless steel, nickel alloy, iron alloy, molybdenum, titanium and alloys, combinations and laminations thereof.
Claim 34
Dependent Claim
60 words
The standoff mask of claim 29 wherein said patterned layer of flexible material defines standoff features on one surface of the sheet of metal spaced away from the openings of the pattern of openings, wherein the standoff features are formed by selectively electroplating, selectively electroforming or selectively electro-depositing the same metal onto the one surface of the sheet of metal.
Claim 35
Dependent Claim
27 words
The standoff mask of claim 29 wherein the openings in said metal membrane are formed by at least one of photo-etching, laser machining, electroforming, and die cutting.
Claim 36
Dependent Claim
61 words
The standoff mask of claim 29 further comprising a second patterned layer of flexible material formed on a second side of said metal membrane, said second patterned layer having a pattern of openings therethrough corresponding to the pattern of openings in said metal membrane, wherein said flexible material is a flexible polymer adhesive having a surface energy less than 50 dyne/cm.
Claim 37
Dependent Claim
41 words
The standoff mask of claim 29 wherein said metal membrane and said flexible layer each have a respective thickness, and wherein the aggregate of the respective thicknesses of said metal membrane and said flexible layer is no greater than 100 microns.
Claim 38
Dependent Claim
36 words
The standoff mask of claim 29 wherein said metal membrane and said flexible layer each have a respective thickness, and wherein the thickness of said metal membrane is less than the thickness of said flexible layer.
Claim 39
Dependent Claim
25 words
The standoff mask of claim 29 wherein at least ones of the openings through said metal membrane have a pitch of less than 200 microns.
Claim 40
Dependent Claim
25 words
The standoff mask of claim 37 wherein at least ones of the openings through said metal membrane have a pitch of less than 100 microns.
Claim 41
Dependent Claim
21 words
The standoff mask of claim 29 wherein at least one of said openings has a dimension of less than 200 microns.
Claim 42
Dependent Claim
21 words
The standoff mask of claim 39 wherein at least one of said openings has a dimension of less than 100 microns.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-11-12 | 2005-05-14 | 2005-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-11-12 | 2009-05-14 | 2009-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-11-12 | 2013-05-14 | 2013-11-13 | $7700.00 | Window Closed / Lapsed |