US5043796A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Isolating multiple device mount with stress relief
Assignee: Motorola Solutions Inc
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Filing: 1990-02-06
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Granted: 1991-08-27
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Expires: 2010-02-06
Abstract
Abstract A substrate of copper clad alumina lamina bearing a number of semiconductor dies is adapted to be soldered to a heatsink to provide electrically isolated thermal relief for the dies. Channels of reduced lamina depth are provided between the dies in regions of no cladding to provide a stress relief fracture path. Stresses caused by the mismatch between the thermal coefficient of expansion of the lamina and is heatsink as the substrate is temperature cycled are fracture relieved without risk of die damage or die or substrate detachment.
Inventors
- 👤 Theodore V. Lester
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:11
CPC Classifications
H; H10; H10W; H10W40/00; H10W40/20; H10W40/25; H10W40/255; H10W90/00; H10W90/701; H10W90/731; H10W90/734
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
99 words
An assembly for a substrate and heatsink, comprising: a substrate having sites for mounting a plurality of energy dissipating devices including a lamina of dielectric material possessing a first thermal coefficient of expansion, a heatsink possessing a second thermal coefficient of expansion substantially different from said first thermal coefficient of expansion, said substrate being attached to said heatsink; said substrate having, between said sites, a region of reduced lamina thickness, said region being adapted to constitute a zone of preferential fracture propagation in the event of a thermally induced fracturing stress being applied to said substrate by said heatsink.
Claim 2
Dependent Claim
99 words
An assembly for a substrate and heatsink, comprising: a substrate having sites for mounting a plurality of energy dissipating devices including a lamina of dielectric material possessing a first thermal coefficient of expansion, a heatsink possessing a second thermal coefficient of expansion substantially different from said first thermal coefficient of expansion, said substrate being attached to said heatsink; said substrate having, between said sites, a region of reduced lamina thickness, said region being adapted to constitute a zone of preferential fracture propagation in the event of a thermally induced fracturing stress being applied to said substrate by said heatsink.
Claim 3
Dependent Claim
19 words
An assembly as claimed in claim 1 and wherein said region is continuous from one lamina edge to another.
Claim 4
Dependent Claim
16 words
An assembly as claimed in claim 1 and wherein the region is profiled as a groove.
Claim 5
Dependent Claim
19 words
An assembly as claimed in claim 3 with said substrate having aligned grooves on each side of the lamina.
Claim 6
Dependent Claim
26 words
An assembly as claimed in claim 1 and wherein a plurality of directionally co-operating elongate regions of said substrate provide an extended line of preferential fracture.
Claim 7
Dependent Claim
15 words
An assembly as claimed in claim 5 and wherein said elongate regions have aligned corners.
Claim 8
Dependent Claim
19 words
An assembly as claimed in claim 5 and wherein said elongate regions are constituted by perforation of the lamina.
Claim 9
Dependent Claim
27 words
An assembly as claimed in claim 1 with said substrate having a conductive cladding and including semiconductor devices mounted at said sites on portions of said cladding.
Claim 10
Dependent Claim
20 words
An assembly as claimed in claimed in claim 8 and wherein said cladding spans said zone of preferential fracture propagation.
Claim 11
Dependent Claim
25 words
An assembly as claimed in claim 5 wherein said substrate has a conductive cladding and wherein said cladding spans said extended line of preferential fracture.
Claim 12
Dependent Claim
31 words
An assembly as claimed in claim 1 wherein said substrate comprises a ceramic substrate and wherein said heat sink comprises a metal heat sink on which said ceramic substrate is mounted.
Claim 13
Dependent Claim
28 words
An assembly as claimed in claim 8 wherein said energy dissipating devices comprise said semiconductor devices which comprise semiconductor die which are mounted on portions of said cladding.
References Cited (Backward Citations)
US3829598A
Cited
US4236296A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-08-26 | 1995-02-25 | 1995-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-08-26 | 1999-02-25 | 1999-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-08-26 | 2003-02-25 | 2003-08-27 | $7700.00 | Window Closed / Lapsed |