US5527743A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for encapsulating an integrated circuit package
Assignee: LSI Corp
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Filing: 1995-05-04
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Granted: 1996-06-18
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Expires: 2015-05-04
Abstract
Abstract The present invention provides a method for fabricating an integrated circuit package, as well the resulting integrated circuit package, which retains a heatsink in close communication with a mold cavity. This precludes any encapsulant from flowing between the heatsink and the inner surface of a mold cavity. As a consequence, the bottom of the heatsink is not encapsulated and is thus exposed. This is accomplished by including posts, attached to the leadframe assembly, which have the function of exerting a downward force on a leadframe assembly and, in turn, on the heatsink. Tie bars, which are non-functional parts of a leadframe assembly, can be utilized as posts by bending the posts into an upright position.
Inventors
- 👤 Patrick Variot
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:52
CPC Classifications
H; H10; H10W; H10W74/00; H10W74/01; H10W74/016; H10W40/00; H10W40/70; H10W40/77; H10W40/778; H10W90/00; H10W90/701; H10W90/751; H10W90/756; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49121; Y10T29/49124; Y10T29/4913; Y10T29/49146; Y10T29/49169; Y10T29/49171
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
192 words
A method for fabricating an integrated circuit package that includes a semiconductor die, a heatsink and a leadframe assembly having a plurality of lead tips, the leadframe assembly disposed over a first surface of the heatsink, the semiconductor die disposed in an opening of the leadframe assembly so as to be in thermal communication with the first surface of the heatsink, said method comprising the steps of: (a) forming a plurality of posts from the leadframe assembly by bending portions of the leadframe assembly away from the heatsink a desired distance; (b) placing the leadframe assembly, the plurality of posts, and the semiconductor inside an open mold, the plurality of posts extending the desired distance from the heatsink so as to engage a first inside surface of the mold; (c) closing the mold so that the plurality of posts bias the heatsink toward a second inside surface of the mold, whereby any space between the heatsink and the second inside surface of the mold is minimized; and (d) injecting encapsulant into the closed mold, whereby the injected encapsulant flow is minimized between the second inside surface of the mold and the heatsink.
Claim 2
Independent Claim
192 words
A method for fabricating an integrated circuit package that includes a semiconductor die, a heatsink and a leadframe assembly having a plurality of lead tips, the leadframe assembly disposed over a first surface of the heatsink, the semiconductor die disposed in an opening of the leadframe assembly so as to be in thermal communication with the first surface of the heatsink, said method comprising the steps of: (a) forming a plurality of posts from the leadframe assembly by bending portions of the leadframe assembly away from the heatsink a desired distance; (b) placing the leadframe assembly, the plurality of posts, and the semiconductor inside an open mold, the plurality of posts extending the desired distance from the heatsink so as to engage a first inside surface of the mold; (c) closing the mold so that the plurality of posts bias the heatsink toward a second inside surface of the mold, whereby any space between the heatsink and the second inside surface of the mold is minimized; and (d) injecting encapsulant into the closed mold, whereby the injected encapsulant flow is minimized between the second inside surface of the mold and the heatsink.
Claim 3
Dependent Claim
51 words
The method as recited in claim 1, wherein the desired distance is greater than the distance between the first inside surface of the mold and the leadframe assembly so that the plurality of posts springingly bias the heatsink toward the second inside surface of the mold when the mold is closed.
Claim 4
Dependent Claim
18 words
The method as recited in claim 1, wherein at least four posts are formed from the leadframe assembly.
Claim 5
Dependent Claim
24 words
The method as recited in claim 1, wherein the leadframe assembly includes a-plurality of tie bars from which the plurality of posts are formed.
Claim 6
Dependent Claim
28 words
The method as recited in claim 1, wherein the plurality of posts are perpendicular to the leadframe assembly and extend away from the first surface of the heatsink.
Claim 7
Dependent Claim
32 words
The method as recited in claim 1, wherein the plurality of posts are formed by bending the portions of the leadframes from 45 to 90 degrees from the plane of the leadframe.
Claim 8
Dependent Claim
32 words
The method as recited in claim 1, wherein the plurality of posts are formed by bending the portions of the leadframes from 10 to 90 degrees from the plane of the leadframe.
Claim 9
Independent Claim
207 words
A method for fabricating an integrated circuit package by encapsulating a semiconductor die connected to a leadframe and attached to a heatsink, said method comprising the steps of: attaching the leadframe to the heatsink attaching the semiconductor die to the heatsink; connecting the semiconductor die to the leadframe; bending portions of the leadframe away from the heatsink a desired distance; placing the semiconductor die, leadframe and heatsink into a first portion of an encapsulation mold so that the heatsink is in contact with a first inside surface of the first portion of the mold; placing a second portion of the encapsulation mold over the semiconductor die, leadframe and heatsink so that a second inside surface of the second portion of the mold is in contact with the bent portions of the leadframe, wherein the bent portions of the leadframe springingly bias the heatsink toward the first inside surface of the first portion of the mold; and injecting encapsulant into the first and second portions of the encapsulation mold so as to encapsulate the semiconductor die, leadframe and heatsink, wherein the bent portions of the leadframe keep the heatsink in contact with the first inside surface of the first portion of the mold during injection of the encapsulant.
Claim 10
Independent Claim
207 words
A method for fabricating an integrated circuit package by encapsulating a semiconductor die connected to a leadframe and attached to a heatsink, said method comprising the steps of: attaching the leadframe to the heatsink attaching the semiconductor die to the heatsink; connecting the semiconductor die to the leadframe; bending portions of the leadframe away from the heatsink a desired distance; placing the semiconductor die, leadframe and heatsink into a first portion of an encapsulation mold so that the heatsink is in contact with a first inside surface of the first portion of the mold; placing a second portion of the encapsulation mold over the semiconductor die, leadframe and heatsink so that a second inside surface of the second portion of the mold is in contact with the bent portions of the leadframe, wherein the bent portions of the leadframe springingly bias the heatsink toward the first inside surface of the first portion of the mold; and injecting encapsulant into the first and second portions of the encapsulation mold so as to encapsulate the semiconductor die, leadframe and heatsink, wherein the bent portions of the leadframe keep the heatsink in contact with the first inside surface of the first portion of the mold during injection of the encapsulant.
Claim 11
Independent Claim
235 words
A method for reducing the amount of undesired encapsulate that may form over a heatsink during fabrication of an integrated circuit package containing a semiconductor die attached to a leadframe and heatsink, said method comprising the steps of; bending portions of the leadframe away from the heatsink a desired distance; placing the semiconductor die attached to the leadframe and heatsink into a first portion of an encapsulation mold so that an outer surface of the heatsink is in contact with a first inside surface of the first portion of the mold; placing a second portion of the encapsulation mold over the semiconductor die attached to the leadframe and heatsink so that a second inside surface of the second portion of the mold is in contact with the bent portions of the leadframe, wherein the bent portions of the leadframe springingly bias the outer surface of the heatsink toward the first inside surface of the first portion of the mold; and injecting encapsulant into the first and second portions of the encapsulation mold so as to encapsulate the semiconductor die attached to the leadframe and heatsink, wherein the bent portions of the leadframe keep the outer surface of the heatsink in contact with the first inside surface of the first portion of the mold during injection of the encapsulant such that the amount of undesired encapsulate flowing over the outer surface of the heatsink is reduced.
Claim 12
Independent Claim
235 words
A method for reducing the amount of undesired encapsulate that may form over a heatsink during fabrication of an integrated circuit package containing a semiconductor die attached to a leadframe and heatsink, said method comprising the steps of; bending portions of the leadframe away from the heatsink a desired distance; placing the semiconductor die attached to the leadframe and heatsink into a first portion of an encapsulation mold so that an outer surface of the heatsink is in contact with a first inside surface of the first portion of the mold; placing a second portion of the encapsulation mold over the semiconductor die attached to the leadframe and heatsink so that a second inside surface of the second portion of the mold is in contact with the bent portions of the leadframe, wherein the bent portions of the leadframe springingly bias the outer surface of the heatsink toward the first inside surface of the first portion of the mold; and injecting encapsulant into the first and second portions of the encapsulation mold so as to encapsulate the semiconductor die attached to the leadframe and heatsink, wherein the bent portions of the leadframe keep the outer surface of the heatsink in contact with the first inside surface of the first portion of the mold during injection of the encapsulant such that the amount of undesired encapsulate flowing over the outer surface of the heatsink is reduced.
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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) | 1999-06-18 | 1999-12-18 | 2000-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-06-18 | 2003-12-18 | 2004-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-06-18 | 2007-12-18 | 2008-06-18 | $7700.00 | Window Closed / Lapsed |