Patent US4952999A successfully refreshed from Google Patents.
US4952999A
Expired / Lapsed
US
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Method and apparatus for reducing die stress
Assignee: National Semiconductor Corp
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Filing: 1988-04-26
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Granted: 1990-08-28
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Expires: 2008-04-26
Abstract
Abstract A slotted metallic die attach pad is disclosed for attachment of a semiconductor die, such as a silicon die, to form a die assembly demonstrating significantly reduced die attach stress. A plurality of substantially parallel, unidirectional slots in the die attach pad permits deformation of the die attach pad at the slots to compensate for differences in the thermal expansion coefficients of the silicon die and the metallic die attach pad. Stress sensitive components of the die are aligned in a stress sensitive direction, and the die is bonded on the die attach pad so that the stress sensitive direction is generally orthogonal to the longitudinal axes of the slots. A method for relieving die stress in a die assembly is also disclosed.
Inventors
- 👤 Murray J. Robinson
- 👤 Ywan-Lung Tsay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:36
CPC Classifications
H; H10; H10W; H10W70/00; H10W70/40; H10W70/411
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
88 words
A die assembly comprising an integrated circuit semiconductor die bonded to a metallic die attach pad, wherein said die attach pad has a plurality of substantially parallel, unidirectional slots extending from a top surface of said die attach pad through to a bottom surface of said die attach pad, said semiconductor die having stress-sensitive components formed in said semiconductor die generally aligned in a stress-sensitive direction, said substantially unidirectional slots being oriented substantially orthogonal to the stress sensitive direction of said stress sensitive components in said semiconductor die.
Claim 2
Dependent Claim
88 words
A die assembly comprising an integrated circuit semiconductor die bonded to a metallic die attach pad, wherein said die attach pad has a plurality of substantially parallel, unidirectional slots extending from a top surface of said die attach pad through to a bottom surface of said die attach pad, said semiconductor die having stress-sensitive components formed in said semiconductor die generally aligned in a stress-sensitive direction, said substantially unidirectional slots being oriented substantially orthogonal to the stress sensitive direction of said stress sensitive components in said semiconductor die.
Claim 3
Dependent Claim
29 words
A die assembly according to claim 1 wherein said plurality of substantially parallel, unidirectional slots extend for at least about 40% of the length of the die attach pad.
Claim 4
Dependent Claim
27 words
A die assembly according to claim 1, wherein each of said substantially parallel, unidirectional slots has a slot width of from about 0.5 to about 20 mils.
Claim 5
Dependent Claim
26 words
A die assembly according to claim 3, wherein each of said substantially parallel, unidirectional slots has a width of from about 2 to about 12 mils.
Claim 6
Dependent Claim
21 words
A die assembly according to claim 1, wherein said slots in said plurality of substantially parallel, unidirectional slots are uniformly spaced.
Claim 7
Dependent Claim
30 words
A die assembly according to claim 5, wherein each of said substantially unidirectional slots is spaced a distance of about 10 to about 40 mil from an adjacent said slot.
Claim 8
Dependent Claim
31 words
A die assembly according to claim 6, wherein each of said substantially parallel, unidirectional slots is spaced a distance of about 10 to about 25 mil from the adjacent said slot.
Claim 9
Dependent Claim
20 words
A die assembly according to claim 1, wherein said die attach pad has from about three to about twelve slots.
Claim 10
Dependent Claim
20 words
A die assembly according to claim 8, wherein said die attach pad has from about four to about nine slots.
Claim 11
Dependent Claim
17 words
A die assembly according to claim 1, wherein the integrated circuit semiconductor die is a silicon die.
Claim 12
Dependent Claim
98 words
In a die assembly of the type wherein a semiconductor die having stress sensitive components is bonded to a metallic die attach pad, the improvements comprising: a plurality of substantially parallel, unidirectional slots being provided in said metallic die attach pad extending from a top surface of said metallic die attach pad through to a bottom surface of said metallic die attach pad; said stress sensitive components of said semiconductor die being arranged in a stress sensitive direction; said stress sensitive direction of said stress sensitive components being arranged generally orthogonal to the longitudinal axes of said slots.
Claim 13
Dependent Claim
98 words
In a die assembly of the type wherein a semiconductor die having stress sensitive components is bonded to a metallic die attach pad, the improvements comprising: a plurality of substantially parallel, unidirectional slots being provided in said metallic die attach pad extending from a top surface of said metallic die attach pad through to a bottom surface of said metallic die attach pad; said stress sensitive components of said semiconductor die being arranged in a stress sensitive direction; said stress sensitive direction of said stress sensitive components being arranged generally orthogonal to the longitudinal axes of said slots.
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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) | 1993-08-27 | 1994-02-26 | 1994-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-27 | 1998-02-26 | 1998-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-27 | 2002-02-26 | 2002-08-28 | $7700.00 | Window Closed / Lapsed |