US5289964A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluxless soldering process
Assignee: Denso Corp
•
Filing: 1992-07-21
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Granted: 1994-03-01
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Expires: 2012-07-21
Abstract
Abstract A fluxless soldering process comprising the steps of: preparing first and second members to be bonded by soldering, the first member having a bonding surface with a higher solder-wettability and the second member having a bonding surface with a lower solder-wettability; placing the second member with the bonding surface thereof facing upward, a solder foil on the bonding surface of the second member, and the first member on the solder foil and with the bonding surface thereof facing downward, to form an assembly; heating the assembly in a reducing atmosphere to fuse the solder foil, thereby forming a molten solder between the first and second members; and cooling the assembly to solidify the molten solder, thereby bonding the first and second members.
Inventors
- 👤 Takao Yoneyama
- 👤 Katsuhiro Izuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:53
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/001; B23K35/004; B23K1/00; B23K1/012; B23K35/02; B23K35/0222; B23K35/0233
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
117 words
A fluxless soldering process comprising the steps of: preparing first and second members to be bonded by soldering, the first member having a bonding surface with a higher solder-wettability and the second member having a bonding surface with a lower solder-wettability and having a cross-sectional area smaller than that of the bonding surface of the first member; placing the second member with the bonding surface thereof facing upward, a solder foil on the bonding surface of the second member, and the first member on the solder foil with the bonding surface thereof facing downward, to form an assembly; heating the assembly in a reducing atmosphere to fuse the solder foil, thereby bonding the first and second members.
Claim 2
Dependent Claim
117 words
A fluxless soldering process comprising the steps of: preparing first and second members to be bonded by soldering, the first member having a bonding surface with a higher solder-wettability and the second member having a bonding surface with a lower solder-wettability and having a cross-sectional area smaller than that of the bonding surface of the first member; placing the second member with the bonding surface thereof facing upward, a solder foil on the bonding surface of the second member, and the first member on the solder foil with the bonding surface thereof facing downward, to form an assembly; heating the assembly in a reducing atmosphere to fuse the solder foil, thereby bonding the first and second members.
Claim 3
Dependent Claim
25 words
A fluxless soldering process according to claim 1, wherein the bonding surface of the second member is covered with a thin oxide film formed thereon.
Claim 4
Dependent Claim
23 words
A fluxless soldering process according to claim 2, wherein the second member is prepared by depositing a metal layer on a glass material.
Claim 5
Dependent Claim
17 words
A fluxless soldering process according to claim 1, wherein the first member is made of a metal.
Claim 6
Dependent Claim
22 words
A fluxless soldering process according to claim 1, wherein the reducing atmosphere is composed of a gas mixture of hydrogen and nitrogen.
Claim 7
Dependent Claim
22 words
A fluxless soldering process according to claim 2, wherein the reducing atmosphere is composed of a gas mixture of hydrogen and nitrogen.
Claim 8
Dependent Claim
46 words
A fluxless soldering process according to claim 6, wherein the oxide film on the bonding surface of the second member has a thickness of less than about 15 Å and the gas mixture has a composition of more than 30% hydrogen with the rest being nitrogen.
Claim 9
Dependent Claim
35 words
A fluxless soldering process according to claim 1, wherein the bonding surface of the second member has a size of from about 0.4 mm to about 1 mm in terms of a minimum cross-sectional dimension.
Claim 10
Dependent Claim
26 words
A fluxless soldering process according to claim 3, wherein the heating is carried out at a temperature of from about 250° C. to about 300° C.
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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) | 1997-02-28 | 1997-08-30 | 1998-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-28 | 2001-08-30 | 2002-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-02-28 | 2005-08-30 | 2006-03-01 | $7700.00 | Window Closed / Lapsed |