US5852257A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical module with fluxless laser reflow soldered joints
Assignee: Viavi Solutions Inc
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Filing: 1996-05-30
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Granted: 1998-12-22
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Expires: 2016-05-30
Abstract
Abstract An optic module contains a flexible circuit board forming a cable which connects between an optical sub-assembly and a rigid interconnect structure within the optic module. One end of the cable includes lands proximate to through holes for soldered connection to pins which extend from the optical sub-assemblies. At the other end of the cable leads extend across interconnection pads on the surface of the rigid interconnect structure for soldered connection. The top surface of the interconnect pads is 10/90 (Sn/Pb) solder to provide a high temperature soldered joint. Solder flux can not be used because cleaning solvents would contaminate the interconnect structure. An atmosphere of formic acid mixed with nitrogen surrounds the lead and pad and a fluxless solder joint is formed.
Inventors
- 👤 Eberhard Siegfried Dittman
- 👤 Mukund Kantilal Saraiya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:14
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/22; B23K35/24; B23K35/26; B23K35/268; B23K1/00; B23K1/005; B23K1/0056; G; G02; G02B; G02B6/00; G02B6/24; G02B6/42; G02B6/4201; G02B6/4219; G02B6/4236; G02B6/4238; G02B6/4246; G02B6/4292; H; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/325; H05K3/326; H05K3/34; H05K3/341; H05K3/3421; H05K3/3447; H05K3/346; H05K3/36; H05K3/361; H05K3/363; B23K2101/00; B23K2101/36; B23K2101/40; G02B6/4256; G02B6/4262; G02B6/4263; G02B6/4266; G02B6/4268; G02B6/4269; G02B6/4274; G02B6/428; G02B6/4281; H05K1/00; H05K1/02; H05K1/03; H05K1/0393; H05K1/11; H05K1/118; H05K2201/00; H05K2201/03; H05K2201/0332; H05K2201/0388; H05K2201/0397; H05K2201/10; H05K2201/10007; H05K2201/10121; H05K2201/10431; H05K2201/1059; H05K2203/00; H05K2203/01; H05K2203/0195; H05K2203/10; H05K2203/107; H05K3/306; H05K3/3465; H05K3/3468; H05K3/3494; H05K3/366; H05K3/40; H05K3/4092; Y; Y02; Y02P; Y02P70/00; Y02P70/50
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
80 words
An electrical assembly, comprising: an interconnect structure having an electric circuit including an electrically conductive pad for soldered connection on a surface of the interconnect structure and an electrically conductive pathway connected to the conductive pad; a solder pad of Pb and 3-20% Sn connected to the surface of the conductive pad; a lead of an electrical component positioned across a surface of the solder pad; and a laser reflow soldered joint connecting between the solder pad and the lead.
Claim 2
Dependent Claim
80 words
An electrical assembly, comprising: an interconnect structure having an electric circuit including an electrically conductive pad for soldered connection on a surface of the interconnect structure and an electrically conductive pathway connected to the conductive pad; a solder pad of Pb and 3-20% Sn connected to the surface of the conductive pad; a lead of an electrical component positioned across a surface of the solder pad; and a laser reflow soldered joint connecting between the solder pad and the lead.
Claim 3
Dependent Claim
14 words
The electrical assembly of claim 1, in which the reflow soldered joint is fluxless.
Claim 4
Dependent Claim
20 words
The electrical assembly of claim 1, in which the lead is a thin copper film less than 0.3 mm thick.
Claim 5
Dependent Claim
17 words
The electrical assembly of claim 1, in which the lead is covered with a solder wettable coating.
Claim 6
Dependent Claim
16 words
The electrical assembly of claim 1, in which the conductive pad is on a ceramic substrate.
Claim 7
Dependent Claim
121 words
An electrical assembly, comprising: an interconnect structure having an electrical circuit including electrical conductors and conductive pads for soldered connection on a surface of the structure connected to the conductors; a flexible ribbon cable including: at least one flexible conductive layer patterned to provide multiple conductive paths which extend outward as leads from one end of the flexible ribbon cable; and at least one flexible dielectric layer on a major surface of the conductive layer, which does not extend completely over the leads; a solder pad of Pb and 3-20% Sn solder on one of the conductive pads on the surface of the interconnect structure for each respective lead; and a reflow solder joint between each solder pad and respective lead.
Claim 8
Dependent Claim
121 words
An electrical assembly, comprising: an interconnect structure having an electrical circuit including electrical conductors and conductive pads for soldered connection on a surface of the structure connected to the conductors; a flexible ribbon cable including: at least one flexible conductive layer patterned to provide multiple conductive paths which extend outward as leads from one end of the flexible ribbon cable; and at least one flexible dielectric layer on a major surface of the conductive layer, which does not extend completely over the leads; a solder pad of Pb and 3-20% Sn solder on one of the conductive pads on the surface of the interconnect structure for each respective lead; and a reflow solder joint between each solder pad and respective lead.
Claim 9
Dependent Claim
14 words
The electrical assembly of claim 6, in which the reflow solder joint is fluxless.
Claim 10
Dependent Claim
21 words
The electrical assembly of claim 6, in which the conductive layer is a thin copper film less than 0.3 mm thick.
Claim 11
Dependent Claim
17 words
The electrical assembly of claim 6, in which the leads are covered with a solder wettable coating.
Claim 12
Dependent Claim
16 words
The electrical assembly of claim 6, in which the conductive pads are on a ceramic substrate.
Claim 13
Dependent Claim
164 words
An electrical assembly, comprising: an interconnect structure having an electrically conductive circuit on a top surface in which the circuit includes electrical conductors connected to conductive pads on the top surface for soldered connections; a flexible ribbon cable including: a layer of copper film less than 0.3 mm thick to provide desired flexibility and reliability and patterned to provide a multiple of conductive paths which extend as leads from one end of the flexible ribbon cable; a coating of solder on each of the leads; and a flexible dielectric layer less than 0.1 mm thick to provide desired flexibility positioned on each of the conductive paths and which does not extend onto the leads; a solder pad of Pb and 3-20% Sn solder connected on top of one of the conductive pads on the top surface of the interconnect structure for each respective lead; and a fluxless reflow solder joint of Pb and 3-20% Sn solder connecting between each lead and respective solder pad.
Claim 14
Dependent Claim
164 words
An electrical assembly, comprising: an interconnect structure having an electrically conductive circuit on a top surface in which the circuit includes electrical conductors connected to conductive pads on the top surface for soldered connections; a flexible ribbon cable including: a layer of copper film less than 0.3 mm thick to provide desired flexibility and reliability and patterned to provide a multiple of conductive paths which extend as leads from one end of the flexible ribbon cable; a coating of solder on each of the leads; and a flexible dielectric layer less than 0.1 mm thick to provide desired flexibility positioned on each of the conductive paths and which does not extend onto the leads; a solder pad of Pb and 3-20% Sn solder connected on top of one of the conductive pads on the top surface of the interconnect structure for each respective lead; and a fluxless reflow solder joint of Pb and 3-20% Sn solder connecting between each lead and respective solder pad.
Claim 15
Dependent Claim
14 words
The electrical assembly of claim 4 in which the coating includes a Pb/Sn solder.
Claim 16
Dependent Claim
22 words
The assembly of claim 1 in which the solder pad is plated onto the conductive pad and is approximately 4 mils thick.
Claim 17
Dependent Claim
17 words
The assembly of claim 1 in which the solder pad is Pb and 3-10% Sn solder alloy.
Claim 18
Dependent Claim
31 words
The electrical assembly of claim 1 in which a portion of the lead remote from the solder joint is covered by a flexible layer of dielectric less than 0.1 mm thick.
Claim 19
Dependent Claim
67 words
The electrical assembly of claim 6 in which the flexible conductive layer of the flexible ribbon cable comprises: a layer of copper film less than 0.3 mm thick and having a second major surface, and the at least one flexible dielectric layer comprises two dielectric layers, each of the two dielectric layers being positioned on a respective one of the two major surfaces of the copper film.
Claim 20
Dependent Claim
22 words
The electrical assembly of claim 6 in which one or more of the conductive paths are conductive ink that has been fired.
Claim 21
Dependent Claim
22 words
The assembly of claim 6 in which the solder pad is plated onto the conductive pad and is approximately 4 mils thick.
Claim 22
Dependent Claim
17 words
The assembly of claim 6 in which the solder pad is Pb and 3-10% Sn solder alloy.
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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) | 2001-12-21 | 2002-06-22 | 2002-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-12-21 | 2006-06-22 | 2006-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-12-21 | 2010-06-22 | 2010-12-22 | $7700.00 | Window Closed / Lapsed |