US5829124A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming metallized patterns on the top surface of a printed circuit board
Assignee: International Business Machines Corp
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Filing: 1995-12-29
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Granted: 1998-11-03
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Expires: 2015-12-29
Abstract
Abstract A method for attaching pads to a high density printed circuit board (PCB) having a plurality of through-holes opening on the top surface. The method includes forming a plurality of pads on a carrier sheet so that each of said pads have a copper layer proximate to said carrier sheet and a joining metal layer formed on top of said copper layer, positioning the plurality of pads on the carrier sheet so that they are aligned with the through-hole pattern on the top surface of the PCB, laminating the pads to the through-holes on the top surface using the joining metal, and separating the carrier sheet from the plurality of pads that are joined to the through-holes so that the copper layer is exposed. The pads may comprise a variety of shapes such as disk-shaped, elongated, or rectangular, and can cover one or multiple through-holes. An electrical component may be soldered to the pad. The method advantageously prevents wicking of the solderball volume into the through-hole, thereby increasing yield and part reliability. In one embodiment, the pad and through-hole may be compressed so that the top surface of the pad is even (flush) with the top surface of the external dielectric surface.
Inventors
- 👤 John Steven Kresge
- 👤 David Noel Light
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 09:40
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/40; H05K3/4007; H05K3/4015; H05K3/30; H05K3/32; H05K3/34; H05K1/00; H05K1/02; H05K1/11; H05K1/111; H05K1/112; H05K1/113; H05K2201/00; H05K2201/03; H05K2201/0332; H05K2201/0364; H05K2201/0376; H05K2201/09; H05K2201/09209; H05K2201/095; H05K2201/096; H05K2201/10; H05K2201/10227; H05K2201/1025; H05K2203/00; H05K2203/02; H05K2203/0278; H05K2203/13; H05K2203/1377; H05K2203/1394; H05K3/0094; H05K3/46; H05K3/4611; H05K3/4614; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49124; Y10T29/4913; Y10T29/49144
Claims Analysis
Total Claims: 60
Claim 1
Independent Claim
140 words
A method for attaching pads to a high density printed circuit board having a plurality of through-holes opening on the top surface, comprising the steps of: a) forming a plurality of pads in a predetermined pattern on a carrier layer so that each of said pads have a copper layer proximate to said carrier layer and a joining metal layer formed on top of said copper layer; b) positioning the plurality of pads on the carrier layer so that they are aligned with the through-hole pattern on the top surface of the circuit board; c) bonding the pads to the through-holes on the top surface using the joining metal layer for said bonding; and d) after step (c) separating the carrier layer from the plurality of pads that are bonded to the through-holes, so that the copper layer is exposed.
Claim 2
Independent Claim
140 words
A method for attaching pads to a high density printed circuit board having a plurality of through-holes opening on the top surface, comprising the steps of: a) forming a plurality of pads in a predetermined pattern on a carrier layer so that each of said pads have a copper layer proximate to said carrier layer and a joining metal layer formed on top of said copper layer; b) positioning the plurality of pads on the carrier layer so that they are aligned with the through-hole pattern on the top surface of the circuit board; c) bonding the pads to the through-holes on the top surface using the joining metal layer for said bonding; and d) after step (c) separating the carrier layer from the plurality of pads that are bonded to the through-holes, so that the copper layer is exposed.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein said step (a) includes sputtering and electroplating copper on the carrier layer.
Claim 4
Dependent Claim
11 words
The method of claim 1 wherein said carrier layer comprises polyimide.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein said carrier layer comprises stainless steel.
Claim 6
Dependent Claim
15 words
The method of claim 1 wherein said step (a) comprises electroplating the joining metal layer.
Claim 7
Dependent Claim
15 words
The method of claim 5 wherein said joining metal layer comprises gold and tin films.
Claim 8
Dependent Claim
17 words
The method of claim 1 wherein said step of bonding comprises a transient liquid phase (TLP) process.
Claim 9
Dependent Claim
31 words
The method of claim 7 wherein said joining metal layer comprises gold and tin films and said TLP process comprises heating said gold and tin films to form a gold-tin alloy.
Claim 10
Dependent Claim
58 words
The method of claim 1 wherein said printed circuit board defines a top surface comprising a dielectric material, and said step (c) includes compressing the plurality of pads into the printed circuit board so that the outermost surface of said plurality of pads is flush with the top surface of the dielectric layer in the printed circuit board.
Claim 11
Dependent Claim
23 words
The method of claim 1 further comprising the step of mounting an electrical component to at least one of said plurality of pads.
Claim 12
Dependent Claim
17 words
The method of claim 10 wherein said step of mounting an electrical component comprises applying a solderball.
Claim 13
Dependent Claim
42 words
The method of claim 1 wherein at least one of said plurality of pads has a shape for covering at least two through-holes in said printed circuit board, and said bonding step includes bonding said pad to said at least two through-holes.
Claim 14
Independent Claim
169 words
A method for forming a high density multilayer printed circuit board having a plurality of through-holes opening on the top surface, comprising the steps of: a) forming a plurality of pads in a predetermined pattern on a carrier layer so that each of said pads have a copper layer proximate to said carrier sheet and a joining metal layer formed on top of said copper layer; b) aligning a plurality of preformed core circuit boards having a predefined through-hole pattern, said plurality of boards including a top board having a top surface having externally-opening through-holes; c) positioning the plurality of pads on the carrier layer so that they are aligned with the through-hole pattern on the top surface; d) bonding the pads to the through-holes on the top surface using the joining metal layer and simultaneously laminating the plurality of boards to provide a multilayer structure; e) separating the carrier layer from the plurality of pads that are joined to the through-holes, so that the copper layer is exposed.
Claim 15
Independent Claim
169 words
A method for forming a high density multilayer printed circuit board having a plurality of through-holes opening on the top surface, comprising the steps of: a) forming a plurality of pads in a predetermined pattern on a carrier layer so that each of said pads have a copper layer proximate to said carrier sheet and a joining metal layer formed on top of said copper layer; b) aligning a plurality of preformed core circuit boards having a predefined through-hole pattern, said plurality of boards including a top board having a top surface having externally-opening through-holes; c) positioning the plurality of pads on the carrier layer so that they are aligned with the through-hole pattern on the top surface; d) bonding the pads to the through-holes on the top surface using the joining metal layer and simultaneously laminating the plurality of boards to provide a multilayer structure; e) separating the carrier layer from the plurality of pads that are joined to the through-holes, so that the copper layer is exposed.
Claim 16
Dependent Claim
18 words
The method of claim 13 wherein said step (a) includes sputtering and electroplating copper on the carrier layer.
Claim 17
Dependent Claim
11 words
The method of claim 13 wherein said carrier layer comprises polyimide.
Claim 18
Dependent Claim
12 words
The method of claim 13 wherein said carrier layer comprises stainless steel.
Claim 19
Dependent Claim
15 words
The method of claim 13 wherein said step (a) comprises electroplating the joining metal layer.
Claim 20
Dependent Claim
15 words
The method of claim 17 wherein said joining metal layer comprises gold and tin films.
Claim 21
Dependent Claim
19 words
The method of claim 13 wherein the steps of bonding and laminating comprise a transient liquid phase (TLP) process.
Claim 22
Dependent Claim
31 words
The method of claim 19 wherein said joining metal layer comprises gold and tin films and said TLP process comprises heating said gold and tin films to form a gold-tin alloy.
Claim 23
Dependent Claim
56 words
The method of claim 13 wherein said multilayer circuit defines a top surface comprising a dielectric material, and said step (d) includes compressing the plurality of pads into the multilayer structure so that the outermost surface of said plurality of pads is flush with the top surface of the dielectric layer in the resulting multilayer structure.
Claim 24
Dependent Claim
23 words
The method of claim 13 further comprising the step of mounting an electrical component to at least one of said plurality of pads.
Claim 25
Dependent Claim
17 words
The method of claim 13 wherein said step of mounting an electrical component comprises applying a solderball.
Claim 26
Dependent Claim
41 words
The method of claim 13 wherein at least one of said plurality of pads has a shape for covering at least two through-holes in said multilayer structure, and said bonding step includes bonding said pad to said at least two through-holes.
Claim 27
Independent Claim
214 words
A method for attaching pads to a high density multilayer printed circuit board having a plurality of through-holes opening on the top surface, comprising the steps of: a) forming a plurality of pads on a carrier layer, including the substeps of a.i) depositing a copper surface layer on the carrier layer to provide a copper-surfaced carrier layer, a.ii) applying photoresist to the copper-surfaced carrier layer, a.iii) exposing said photoresist on the copper-surfaced carrier layer to light with a predetermined pad pattern, a.iv) developing and washing the exposed photoresist from step a.iii to provide a plurality of exposed copper layer areas having the predetermined pad pattern; a.v) depositing copper pads on the plurality of exposed copper layer areas, a.vi) depositing a joining metal layer on each copper pad deposited in the previous step, and a.vii) stripping the resist layer and the copper layer, except copper layer portions under the pads, from the carrier layer; b) positioning the plurality of pads on the carrier layer so that they are aligned with the through-hole pattern on the top surface of the multilayer circuit board; c) bonding the pads to the through-holes on the top surface using the joining metal layer; and d) separating the carrier layer from the plurality of pads that are joined to the through-holes.
Claim 28
Independent Claim
214 words
A method for attaching pads to a high density multilayer printed circuit board having a plurality of through-holes opening on the top surface, comprising the steps of: a) forming a plurality of pads on a carrier layer, including the substeps of a.i) depositing a copper surface layer on the carrier layer to provide a copper-surfaced carrier layer, a.ii) applying photoresist to the copper-surfaced carrier layer, a.iii) exposing said photoresist on the copper-surfaced carrier layer to light with a predetermined pad pattern, a.iv) developing and washing the exposed photoresist from step a.iii to provide a plurality of exposed copper layer areas having the predetermined pad pattern; a.v) depositing copper pads on the plurality of exposed copper layer areas, a.vi) depositing a joining metal layer on each copper pad deposited in the previous step, and a.vii) stripping the resist layer and the copper layer, except copper layer portions under the pads, from the carrier layer; b) positioning the plurality of pads on the carrier layer so that they are aligned with the through-hole pattern on the top surface of the multilayer circuit board; c) bonding the pads to the through-holes on the top surface using the joining metal layer; and d) separating the carrier layer from the plurality of pads that are joined to the through-holes.
Claim 29
Dependent Claim
14 words
The method of claim 25 wherein said carrier layer comprises a peelable polyimide layer.
Claim 30
Dependent Claim
15 words
The method of claim 25 wherein said carrier layer comprises a peelable stainless steel layer.
Claim 31
Dependent Claim
15 words
The method of claim 25 wherein said step a.vi comprises electroplating the joining metal layer.
Claim 32
Dependent Claim
15 words
The method of claim 25 wherein said joining metal layer comprises gold and tin films.
Claim 33
Dependent Claim
19 words
The method of claim 25 wherein said steps of bonding and laminating comprise a transient liquid phase (TLP) process.
Claim 34
Dependent Claim
31 words
The method of claim 30 wherein said joining metal layer comprises gold and tin films and said TLP process comprises heating said gold and tin films to form a gold-tin alloy.
Claim 35
Dependent Claim
56 words
The method of claim 25 wherein said multilayer circuit defines a top surface comprising a dielectric material, and said step (c) includes compressing the plurality of pads into the multilayer structure so that the outermost surface of said plurality of pads is flush with the top surface of the dielectric layer in the resulting multilayer structure.
Claim 36
Dependent Claim
23 words
The method of claim 25 further comprising the step of mounting an electrical component to at least one of said plurality of pads.
Claim 37
Dependent Claim
17 words
The method of claim 33 wherein said step of mounting an electrical component comprises applying a solderball.
Claim 38
Dependent Claim
43 words
The method of claim 25 wherein at least one of said plurality of pads has a shape for covering at least two through-holes in said multilayer structure, and said bonding and laminating steps include bonding said pad to said at least two through-holes.
Claim 39
Independent Claim
107 words
A method of forming a multilayer printed circuit board comprising the steps of: forming a plurality of core printed circuit boards (PCBs) including a top core having a top surface that has a plurality of exposed through-holes; forming a plurality of pads in a predetermined pad pattern on a peelable carrier layer; aligning said core PCBs with respect to each other in interconnectable formation; aligning said predetermined pad pattern in alignment with said top surface; heating and compressing said core PCBs and plurality of pads; and peeling away the carrier layer to provide a multilayer PCB board having pads over the through holes in the top surface.
Claim 40
Independent Claim
107 words
A method of forming a multilayer printed circuit board comprising the steps of: forming a plurality of core printed circuit boards (PCBs) including a top core having a top surface that has a plurality of exposed through-holes; forming a plurality of pads in a predetermined pad pattern on a peelable carrier layer; aligning said core PCBs with respect to each other in interconnectable formation; aligning said predetermined pad pattern in alignment with said top surface; heating and compressing said core PCBs and plurality of pads; and peeling away the carrier layer to provide a multilayer PCB board having pads over the through holes in the top surface.
Claim 41
Independent Claim
188 words
A method for attaching pads to a circuit board having a plurality of conductive sites arranged in a predetermined pattern at a top surface of the circuit board, comprising the steps of: forming a plurality of pads on a top surface of a carrier layer so that first ends of the pads are releasable from the carrier layer when the carrier layer is pulled from the first ends of the pads and so that second ends of the pads are in a pattern that match at least a portion of said plurality of conductive sites at the top surface of the circuit board; positioning the carrier layer so that said second ends of the pads engage said at least a portion of the plurality of conductive sites; bonding the second ends of the pads to said at least a portion of the conductive sites; and pulling the carrier layer from the first ends of the pads leaving the second ends of the pads bonded to the conductive sites and the first ends of the pads exposed and extending from said at least a portion of the conductive sites.
Claim 42
Independent Claim
188 words
A method for attaching pads to a circuit board having a plurality of conductive sites arranged in a predetermined pattern at a top surface of the circuit board, comprising the steps of: forming a plurality of pads on a top surface of a carrier layer so that first ends of the pads are releasable from the carrier layer when the carrier layer is pulled from the first ends of the pads and so that second ends of the pads are in a pattern that match at least a portion of said plurality of conductive sites at the top surface of the circuit board; positioning the carrier layer so that said second ends of the pads engage said at least a portion of the plurality of conductive sites; bonding the second ends of the pads to said at least a portion of the conductive sites; and pulling the carrier layer from the first ends of the pads leaving the second ends of the pads bonded to the conductive sites and the first ends of the pads exposed and extending from said at least a portion of the conductive sites.
Claim 43
Dependent Claim
13 words
A method as claimed in claim 37 wherein the carrier layer is flexible.
Claim 44
Dependent Claim
13 words
A method as claimed in claim 38 wherein the carrier layer is polyimide.
Claim 45
Dependent Claim
14 words
A method as claimed in claim 38 wherein the carrier layer is stainless steel.
Claim 46
Dependent Claim
42 words
A method as claimed in claim 37 wherein each conductive site includes a through-hole through the circuit board with a conductive sleeve disposed therein, each conductive sleeve having an edge that is substantially flush with the top surface of the circuit board.
Claim 47
Dependent Claim
45 words
A method as claimed in claim 37 wherein each pad is multilayered with a first layer being copper and a second layer being a bonding layer, the copper layer providing one of said first ends and the bonding layer providing one of said second ends.
Claim 48
Dependent Claim
25 words
A method as claimed in claim 42 wherein the bonding layer is multifilmed with a first film being gold and a second film being tin.
Claim 49
Dependent Claim
26 words
A method as claimed in claim 37 wherein the step of bonding includes heating the pad until the pad joins with one or more conductive sites.
Claim 50
Dependent Claim
26 words
A method as claimed in claim 44 wherein, in addition to heating, the step of bonding includes pressure applied between the pads and the circuit board.
Claim 51
Dependent Claim
49 words
A method as claimed in claim 45 wherein said circuit board includes a dielectric material and the pressure and heating compresses the pads into the dielectric material of the circuit board so that the first surfaces of the pads are flush with the top surface of the circuit board.
Claim 52
Dependent Claim
111 words
A method as claimed in claim 37 wherein the step of forming said plurality of pads comprises the steps of: forming a thin copper layer on the carrier layer; forming a photoresist pattern on the copper layer with openings exposing portions of the thin copper layer at sites for said plurality of pads; electroplating a thick copper layer on each exposed portion of the thin copper layer; electroplating a bonding material layer on each of the thick copper layers to form said pads; removing the photoresist pattern; and etching away the thin copper layer except at said sites thereby leaving pads of copper and bonding material extending from said carrier layer.
Claim 53
Dependent Claim
29 words
A method as claimed in claim 47 wherein said electroplating a bonding material layer includes electroplating multifilms wherein a first film is gold and a second film is tin.
Claim 54
Dependent Claim
13 words
A method as claimed in claim 48 wherein the carrier layer is flexible.
Claim 55
Dependent Claim
26 words
A method as claimed in claim 49 wherein the step of bonding includes heating the pad until the pads bond with one or more conductive sites.
Claim 56
Dependent Claim
26 words
A method as claimed in claim 50 wherein in addition to heating the step of bonding includes pressure applied between the pads and the circuit board.
Claim 57
Dependent Claim
49 words
A method as claimed in claim 51 wherein said circuit board includes a dielectric material and the pressure and heating compresses the pads into the dielectric material of the circuit board so that the first surfaces of the pads are flush with the top surface of the circuit board.
Claim 58
Dependent Claim
57 words
A method as claimed in claim 51 wherein: each conductive site includes a through-hole through the circuit board with a conductive sleeve disposed therein, each conductive sleeve having an edge that is substantially flush with the top surface of the circuit board; and said bonding bonds the pads to one or more edges of the conductive sleeve.
Claim 59
Dependent Claim
13 words
A method as claimed in claim 51 wherein the carrier layer is polyimide.
Claim 60
Dependent Claim
14 words
A method as claimed in claim 51 wherein the carrier layer is stainless steel.
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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) | 2001-11-02 | 2002-05-04 | 2002-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-02 | 2006-05-04 | 2006-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-02 | 2010-05-04 | 2010-11-03 | $7700.00 | Window Closed / Lapsed |