Patent US5817545A successfully refreshed from Google Patents.
US5817545A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pressurized underfill encapsulation of integrated circuits
Assignee: Cornell Research Foundation Inc
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Filing: 1996-01-24
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Granted: 1998-10-06
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Expires: 2016-01-24
Abstract
Abstract A new method and device to encapsulate integrated circuits such as flip chips and BGA packages. A special mold to surrounds the chip to be encapsulated in a cavity, and the encapsulant is injected into the cavity at an elevated pressure, and possibly at an elevated temperature. This shortens the cavity filling time by two or three orders of magnitude, compared to the conventional dispensing process. The reliability of the package is increased by increasing the adhesion of encapsulant to the package, by controlling fillet shape through in-mold curing, and by completely filling the cavity through proper mold design and, optionally, evacuation of the cavity prior to injection. The invention also allows the use of a wider range of encapsulants, including highly viscous material, fast curing materials and reworkable materials.
Inventors
- 👤 Kuo K. Wang
- 👤 Sejin Han
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:54
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/071; H10W72/0711; B; B29; B29C; B29C33/00; B29C33/0038; B29C33/0044; B29C33/02; B29C33/06; B29C33/12; B29C33/14; B29C45/00; B29C45/14; B29C45/14467; B29C45/14639; H10W72/30; H10W74/00; H10W74/01; H10W74/012; H10W74/10; H10W74/15; B29C33/0022; B29C33/10; B29C33/38; B29C33/40; B29C33/405; H10W72/072; H10W72/07251; H10W72/073; H10W72/20; H10W72/851; H10W72/853; H10W72/856
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
143 words
A method of underfill encapsulation of an integrated circuit chip against a substrate, using a mold head for enclosing the chip and encapsulant, comprising the steps of: a) locating the mold head over the chip; b) lowering the mold head into contact with the substrate, the chip fitting within a cavity within the mold head, and the mold head sealing around the periphery of the chip creating a side region for formation of a fillet around the chip, the mold head contacting the upper surface of the chip and holding it in position against the substrate; c) applying a clamping force to the mold head; d) injecting the encapsulant under pressure through an inlet into the cavity, and allowing entrapped air to escape through an air vent in the mold head; and e) lifting of the mold after the completion of encapsulant flow.
Claim 2
Independent Claim
143 words
A method of underfill encapsulation of an integrated circuit chip against a substrate, using a mold head for enclosing the chip and encapsulant, comprising the steps of: a) locating the mold head over the chip; b) lowering the mold head into contact with the substrate, the chip fitting within a cavity within the mold head, and the mold head sealing around the periphery of the chip creating a side region for formation of a fillet around the chip, the mold head contacting the upper surface of the chip and holding it in position against the substrate; c) applying a clamping force to the mold head; d) injecting the encapsulant under pressure through an inlet into the cavity, and allowing entrapped air to escape through an air vent in the mold head; and e) lifting of the mold after the completion of encapsulant flow.
Claim 3
Dependent Claim
24 words
The method of claim 1, further comprising the step, after step (c) thereof, of applying a vacuum to evacuate the air from the cavity.
Claim 4
Dependent Claim
27 words
The method of claim 1, further comprising the step, after step (d) thereof, of curing of the encapsulant in the mold by applying heat to the mold.
Claim 5
Independent Claim
152 words
A method of underfill encapsulation of an integrated circuit chip against a continuous substrate, using a mold head for enclosing the chip and encapsulant, comprising the steps of: a) locating the mold head over the chip; b) lowering the mold head into contact with the substrate, said substrate being continuous under said mold head, the chip fitting within a cavity within the mold head, and the mold head sealing around the periphery of the chip creating a side region for formation of a fillet around the chip, the mold head contacting the upper surface of the chip and holding it in position against the substrate; c) applying a clamping force to the mold head; d) injecting the encapsulant under pressure through an inlet into the cavity, and allowing entrapped air to escape through an air vent in the mold head; and e) lifting of the mold after the completion of encapsulant flow.
Claim 6
Independent Claim
152 words
A method of underfill encapsulation of an integrated circuit chip against a continuous substrate, using a mold head for enclosing the chip and encapsulant, comprising the steps of: a) locating the mold head over the chip; b) lowering the mold head into contact with the substrate, said substrate being continuous under said mold head, the chip fitting within a cavity within the mold head, and the mold head sealing around the periphery of the chip creating a side region for formation of a fillet around the chip, the mold head contacting the upper surface of the chip and holding it in position against the substrate; c) applying a clamping force to the mold head; d) injecting the encapsulant under pressure through an inlet into the cavity, and allowing entrapped air to escape through an air vent in the mold head; and e) lifting of the mold after the completion of encapsulant flow.
Claim 7
Dependent Claim
16 words
The method of claim 4, wherein said pressure ranges from approximately 15 psi to 1,000 psi.
Claim 8
Dependent Claim
22 words
The method of claim 4, further comprising the step, before step (d), of placing at least one dam in said side region.
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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) | 2001-10-05 | 2002-04-06 | 2002-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-05 | 2006-04-06 | 2006-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-05 | 2010-04-06 | 2010-10-06 | $7700.00 | Window Closed / Lapsed |