US4412642A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cast solder leads for leadless semiconductor circuits
Assignee: AT&T Inc
•
Filing: 1982-03-15
•
Granted: 1983-11-01
•
Expires: 2002-03-15
Abstract
Abstract The attachment of leadless chip carriers to printed wiring boards by means of soldering techniques must provide for a spacing between the chip carrier and the board. Such spacing is required for cleaning the area under the chip carrier, protecting the underlying circuitry, and accounting for stresses which may develop due to thermal mismatch between the chip carrier and the board, and to board flexure. Herein disclosed is a lead (15) for semiconductor chip carriers comprising an elongated body of high melting point electrically conductive material, e.g., solder material. Also disclosed is a method for casting such a solder lead, and a method for attaching a plurality of cast solder leads (38) to a leadless chip carrier (20).
Inventors
- 👤 John R. Fisher, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:30
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0444; B; B23; B23K; B23K3/00; B23K3/06; H05; H05K; H05K3/00; H05K3/30; H05K3/32; H05K3/34; H05K3/341; H05K3/3431; H05K3/3436; H05K3/3465; H05K3/3468; H10W; H10W90/00; H10W90/701; H05K2201/00; H05K2201/10; H05K2201/10227; H05K2201/10378; H05K2201/10424; H05K2201/10613; H05K2201/10621; H05K2201/10727; H05K2203/00; H05K2203/01; H05K2203/0104; H05K2203/0113; H05K2203/03; H05K2203/0338; H05K2203/04; H05K2203/0405; H05K2203/041; H05K2203/0415; H05K2203/043; H05K2203/12; H05K2203/128; H05K3/3442; Y; Y02; Y02P; Y02P70/00; Y02P70/50; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49124; Y10T29/49147; Y10T29/49149; Y10T29/49204; Y10T29/49208; Y10T29/49222
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
64 words
A method for forming an electrically conductive lead comprising the steps of: positioning an electrically conductive preform in alignment with a mold cavity of a molding plate; heating the molding plate to a predetermined reflow temperature; applying a force on the preform during the heating step thereby forcing molten preform material into said mold cavity; cooling the molding plate; and removing the applied force.
Claim 2
Independent Claim
64 words
A method for forming an electrically conductive lead comprising the steps of: positioning an electrically conductive preform in alignment with a mold cavity of a molding plate; heating the molding plate to a predetermined reflow temperature; applying a force on the preform during the heating step thereby forcing molten preform material into said mold cavity; cooling the molding plate; and removing the applied force.
Claim 3
Independent Claim
71 words
A method for forming an electrically conductive solder lead comprising the steps of: positioning an electrically conductive solder preform in alignment with a mold cavity of a molding plate; heating the molding plate to a predetermined reflow temperature; applying a force on the solder preform during the heating step thereby forcing molten solder into said mold cavity; cooling the molding plate; and removing the applied force on the cast solder lead.
Claim 4
Independent Claim
71 words
A method for forming an electrically conductive solder lead comprising the steps of: positioning an electrically conductive solder preform in alignment with a mold cavity of a molding plate; heating the molding plate to a predetermined reflow temperature; applying a force on the solder preform during the heating step thereby forcing molten solder into said mold cavity; cooling the molding plate; and removing the applied force on the cast solder lead.
Claim 5
Independent Claim
81 words
A method for forming an array of electrically conductive solder leads comprising the steps of: positioning an electrically conductive solder preform in alignment with each cavity of a plurality of mold cavities of a molding plate; heating the molding plate to a predetermined reflow temperature; applying a force on the solder preforms during the heating step thereby forcing molten solder into the cavities of the molding plate; cooling the molding plate; and removing the applied force on the cast solder leads.
Claim 6
Independent Claim
81 words
A method for forming an array of electrically conductive solder leads comprising the steps of: positioning an electrically conductive solder preform in alignment with each cavity of a plurality of mold cavities of a molding plate; heating the molding plate to a predetermined reflow temperature; applying a force on the solder preforms during the heating step thereby forcing molten solder into the cavities of the molding plate; cooling the molding plate; and removing the applied force on the cast solder leads.
Claim 7
Independent Claim
72 words
A method for attaching an electrically conductive lead to a leadless component comprising the steps of: applying flux to an electrical termination of the component; contacting said electrical termination with a molded cast lead within a mold; heating the component and the molded cast lead to a predetermined reflow temperature; cooling the component and the molded cast lead until the material of said lead solidifies; and removing the lead from the mold.
Claim 8
Independent Claim
72 words
A method for attaching an electrically conductive lead to a leadless component comprising the steps of: applying flux to an electrical termination of the component; contacting said electrical termination with a molded cast lead within a mold; heating the component and the molded cast lead to a predetermined reflow temperature; cooling the component and the molded cast lead until the material of said lead solidifies; and removing the lead from the mold.
Claim 9
Independent Claim
73 words
A method for attaching an electrically conductive solder lead to a leadless component comprising the steps of: applying flux to an electrical termination of the component; contacting said electrical termination with a molded cast solder lead within a mold; heating the component and the molded cast lead to a predetermined reflow temperature; cooling the component and the molded cast lead until the solder material solidifies; and removing the solder lead from the mold.
Claim 10
Independent Claim
73 words
A method for attaching an electrically conductive solder lead to a leadless component comprising the steps of: applying flux to an electrical termination of the component; contacting said electrical termination with a molded cast solder lead within a mold; heating the component and the molded cast lead to a predetermined reflow temperature; cooling the component and the molded cast lead until the solder material solidifies; and removing the solder lead from the mold.
Claim 11
Independent Claim
82 words
A method for attaching a plurality of electrically conductive leads to a leadless chip carrier (LCC) comprising the steps of: applying flux to electrical terminations of the LCC; contacting said electrical terminations with corresponding solder cast leads of a molded cast lead array within a mold; heating the LCC and the molded cast lead array to a predetermined reflow temperature; cooling the LCC and the molded cast lead array until the solder material solidifies; and removing the solder leads from the mold.
Claim 12
Independent Claim
82 words
A method for attaching a plurality of electrically conductive leads to a leadless chip carrier (LCC) comprising the steps of: applying flux to electrical terminations of the LCC; contacting said electrical terminations with corresponding solder cast leads of a molded cast lead array within a mold; heating the LCC and the molded cast lead array to a predetermined reflow temperature; cooling the LCC and the molded cast lead array until the solder material solidifies; and removing the solder leads from the mold.
Claim 13
Independent Claim
160 words
A method for attaching a plurality of electrically conductive leads to a leadless chip carrier (LCC) having a plurality of electrical terminations comprising the steps of: positioning an electrically conductive solder preform in alignment with each cavity of a plurality of mold cavities of a molding plate, said cavities being arranged in a pattern corresponding to said electrical terminations; heating the molding plate to a predetermined reflow temperature while applying a force on the solder preforms thereby forcing molten solder into the cavities of the molding plate; cooling the molding plate; removing the applied force on the cast solder leads; applying flux to the electrical terminations of the LCC; contacting said electrical terminations with corresponding casted solder leads of the molding plate; heating the LCC and the molding plate to said predetermined reflow temperature; cooling the LCC and the molding plate until the solder material solidifies; and separating the LCC with the solder leads attached thereto from the molding plate.
Claim 14
Independent Claim
160 words
A method for attaching a plurality of electrically conductive leads to a leadless chip carrier (LCC) having a plurality of electrical terminations comprising the steps of: positioning an electrically conductive solder preform in alignment with each cavity of a plurality of mold cavities of a molding plate, said cavities being arranged in a pattern corresponding to said electrical terminations; heating the molding plate to a predetermined reflow temperature while applying a force on the solder preforms thereby forcing molten solder into the cavities of the molding plate; cooling the molding plate; removing the applied force on the cast solder leads; applying flux to the electrical terminations of the LCC; contacting said electrical terminations with corresponding casted solder leads of the molding plate; heating the LCC and the molding plate to said predetermined reflow temperature; cooling the LCC and the molding plate until the solder material solidifies; and separating the LCC with the solder leads attached thereto from the molding plate.
Claim 15
Dependent Claim
21 words
A method according to claim 1, 2, 3 or 7 wherein the electrically conductive preform comprises a high melting point material.
Claim 16
Dependent Claim
39 words
A method according to claim 8 wherein said high melting point material is selected from the group consisting of 100% Sn; 96% Sn and 4% Ag; 88% Pb, 10% Sn and 2% Ag; and 75% Pb and 25% In.
Claim 17
Dependent Claim
20 words
A method according to claim 4, 5 or 6 wherein the molded cast lead comprises a high melting point material.
Claim 18
Dependent Claim
39 words
A method according to claim 10 wherein said high melting point material is selected from the group consisting of 100% Sn; 96% Sn and 4% Ag; 88% Pb, 10% Sn and 2% Ag; and 75% Pb and 25% In.
References Cited (Backward Citations)
US3171175A
Cited
US3429040A
Cited
US3589000A
Cited
US3604836A
Cited
US3835531A
Cited
US3864827A
Cited
US3719981A
Cited
US3854521A
Cited
US4179802A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-31 | 1987-05-02 | 1987-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-31 | 1991-05-02 | 1991-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-31 | 1995-05-02 | 1995-11-01 | $7700.00 | Window Closed / Lapsed |