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US4865654A
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US
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Delayed reflow alloy mix solder paste
Assignee: Texas Instruments Inc
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Filing: 1987-12-17
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Granted: 1989-09-12
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Expires: 2007-12-17
Abstract
Abstract A solder paste mixture for soldering surface mount devices to a circuit board using a reflow soldering process which utilize a vapor phase furnace. The solder paste mixture has a metallic content which is 63% tin and 37% lead. The metallic content of the paste consists of 150 micron particles of 100% tin and 150 micron particles of an alloy of 10% tin and 90% lead. Included in the process of soldering components to the circuit board is the step of prebaking the circuit board with solder paste and components in their proper place on the board.
Inventors
- 👤 Neil R. McLellan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:03
CPC Classifications
B; B23; B23K; B23K35/00; B23K35/22; B23K35/24; B23K35/26; B23K35/36; H; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/3465; H05K3/3485; H05K2201/00; H05K2201/02; H05K2201/0203; H05K2201/0263; H05K2201/0272; H05K3/346
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
85 words
A process for forming a solder paste mixture, comprising the steps of: providing a solder paste; providing a plurality of particles of a first alloy which includes up to 100 per cent tin by weight; providing a plurality of particles of a second alloy which includes lead, said second alloy differing from said first alloy; and mixing said solder paste, and said first and second alloys together to form a mixture whose metallic content is approximately sixty-three percent tin and thirty-seven percent lead by weight.
Claim 2
Dependent Claim
85 words
A process for forming a solder paste mixture, comprising the steps of: providing a solder paste; providing a plurality of particles of a first alloy which includes up to 100 per cent tin by weight; providing a plurality of particles of a second alloy which includes lead, said second alloy differing from said first alloy; and mixing said solder paste, and said first and second alloys together to form a mixture whose metallic content is approximately sixty-three percent tin and thirty-seven percent lead by weight.
Claim 3
Dependent Claim
40 words
The process of claim 1, further comprising the steps of: providing that said first alloy is approximately one hundred percent tin by weight; and providing that said second alloy is approximately ten percent tin and ninety percent lead by weight.
Claim 4
Dependent Claim
20 words
The process of claim 2, further comprising the step of: providing that all the particles are approximately spherical in shape.
Claim 5
Dependent Claim
41 words
The process of claim 2, further comprising the step of: sizing the particles to provide a time delay of approximately twelve seconds from the time that the mixture has reached the melting temperature of a eutectic alloy of tin and lead.
Claim 6
Independent Claim
95 words
A method of forming a solder mixture, comprising the steps of: providing a plurality of particles of a first metal alloy which includes tin; providing a plurality of particles of a second metal alloy which includes lead; providing that the first alloy differs from the second alloy; mixing the particles of the first metal alloy with the particles of the second metal alloy proportionately to cause the metallic content of the mixture by weight to have a ratio of tin to lead which is the same as for a eutectic alloy of tin and lead.
Claim 7
Independent Claim
95 words
A method of forming a solder mixture, comprising the steps of: providing a plurality of particles of a first metal alloy which includes tin; providing a plurality of particles of a second metal alloy which includes lead; providing that the first alloy differs from the second alloy; mixing the particles of the first metal alloy with the particles of the second metal alloy proportionately to cause the metallic content of the mixture by weight to have a ratio of tin to lead which is the same as for a eutectic alloy of tin and lead.
Claim 8
Dependent Claim
23 words
The method of claim 5, further comprising the step of: providing that the first and second alloy particles are substantially spherical in shape.
Claim 9
Dependent Claim
26 words
The method of claim 6, further comprising the step of: sizing the first and second alloy particles to have a diameter of approximately one hundred microns.
Claim 10
Dependent Claim
21 words
The method of claim 5, further comprising the step of: suspending the first and second alloy particles in a tacky medium.
Claim 11
Dependent Claim
36 words
The method of claim 5, further comprising the step of: providing that the first alloy is approximately one hundred percent tin and the second alloy is approximately ninety percent lead and ten percent tin by weight.
Claim 12
Dependent Claim
42 words
The method of claim 5, further comprising the step of: sizing the particles to provide a melting delay time, for the mixture, of approximately twelve seconds after the mixture has reached the melting temperature for a eutectic alloy of tin and lead.
References Cited (Backward Citations)
US4373974A
Cited
US4509994A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-09-11 | 1993-03-13 | 1993-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-11 | 1997-03-13 | 1997-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-11 | 2001-03-13 | 2001-09-12 | $7700.00 | Window Closed / Lapsed |