US4943468A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ceramic based substrate for electronic circuit system modules
Assignee: Texas Instruments Inc
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Filing: 1988-10-31
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Granted: 1990-07-24
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Expires: 2008-10-31
Abstract
Abstract An electronic system having a first printed wiring board, a first integrated circuit carrier positionable on the printed wiring board and a substrate having a central portion formed of ceramic material. The substrate central portion has a specific thermal conductivity greater than 1.5×10 -5 Wm 2 /g°C. The substrate may comprise a ceramic material formed in combination with a modifier of the type which increases fracture toughness thereby inhibiting crack initiation and growth. In an alternate form of the invention the elctronic system includes a substrate having a central portion formed of ceramic material and first and second opposing surfaces each clad with a metallic layer of predetermined thickness. The combination of the substrate and the bonded wiring boards provide an effective coefficient of thermal expansion to each wiring board which is sufficiently close to the coefficient of thermal expansion of the carriers so as to prevent solder joint cracking during operation of the system.
Inventors
- 👤 Robert J. Gordon
- 👤 Brian J. Love
- 👤 Robert K. Peterson
- 👤 Burhan Ozmat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:26
CPC Classifications
H; H05; H05K; H05K1/00; H05K1/02; H05K1/14; H05K1/144; H05K1/03; H05K1/0306; H05K1/05; H05K1/053; H05K2201/00; H05K2201/06; H05K2201/068; H05K2201/09; H05K2201/09209; H05K2201/0929; H05K2201/09309; Y; Y10; Y10S; Y10S428/00; Y10S428/907; Y10T; Y10T428/00; Y10T428/24; Y10T428/24802; Y10T428/24917; Y10T428/24926
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
72 words
An electronic system comprising: (a) a first printed wiring board; (b) a first integrated circuit carrier disposed on and secured to said printed wiring board; and (c) a substrate having a central portion formed of ceramic material, said central portion having a specific thermal conductivity greater than 15×10 -6 Wm 2 /g.sup.° C., said substrate including a fist surface, said printed wiring board being secured to and coplanar with said first surface.
Claim 2
Dependent Claim
72 words
An electronic system comprising: (a) a first printed wiring board; (b) a first integrated circuit carrier disposed on and secured to said printed wiring board; and (c) a substrate having a central portion formed of ceramic material, said central portion having a specific thermal conductivity greater than 15×10 -6 Wm 2 /g.sup.° C., said substrate including a fist surface, said printed wiring board being secured to and coplanar with said first surface.
Claim 3
Dependent Claim
41 words
The system of claim 1 including a second printed wiring board, said substrate including a second surface with the second wiring board mounted said second surface, said central portion having a specific thermal conductivity greater than 40×10 -6 Wm 2 /g°C.
Claim 4
Dependent Claim
31 words
The system of claim 1 wherein the central portion of said substrate comprises at least one material taken from the group containing silicon carbide, aluminum nitride, beryllium oxide and boron nitride.
Claim 5
Dependent Claim
39 words
The system of claim 1 wherein said central portion of said substrate further comprises in combination with said ceramic material a modifier which increases the fracture toughness of said substrate to inhibit crack initiation and growth of said substrate.
Claim 6
Dependent Claim
11 words
The system of claim 4 wherein the modifier is titanium diboride.
Claim 7
Dependent Claim
18 words
The system of claim 5 wherein the central portion of said substrate comprises silicon carbide and titanium diboride.
Claim 8
Dependent Claim
22 words
The system of claim 5 wherein the central portion of said substrate comprises 80 percent silicon carbide and 20 percent titanium diboride.
Claim 9
Dependent Claim
70 words
The system of claim 1 wherein: the first printed wiring board is bonded to the first surface of said substrate and the first integrated circuit carrier is soldered to the printed wiring board; and the effective coefficient of thermal expansion of the bonded wiring board is either identical with or sufficiently close to that of the carrier so as to prevent solder joint cracking during thermal cycling of the system.
Claim 10
Dependent Claim
44 words
The system of claim 7 wherein the effective coefficient of thermal expansion of the bonded wiring board is sufficiently close to that of the carrier so as to prevent solder joint cracking during thermal cycling of the system from -65° C. to 125° C.
Claim 11
Dependent Claim
100 words
An electronic system comprising: a substrate having a central portion formed of ceramic material and first and second opposing surfaces each surface clad with a metallic layer of predetermined thickness; one or more printed wiring boards bonded to each substrate surface; a plurality of integrated circuit carriers each soldered to a printed wiring board, the combination of said substrate and said bonded wiring boards providing an effective coefficient of thermal expansion to each wiring board which is sufficiently close to the coefficient of thermal expansion of the carriers so as to prevent solder joint cracking during operation of the system.
Claim 12
Dependent Claim
100 words
An electronic system comprising: a substrate having a central portion formed of ceramic material and first and second opposing surfaces each surface clad with a metallic layer of predetermined thickness; one or more printed wiring boards bonded to each substrate surface; a plurality of integrated circuit carriers each soldered to a printed wiring board, the combination of said substrate and said bonded wiring boards providing an effective coefficient of thermal expansion to each wiring board which is sufficiently close to the coefficient of thermal expansion of the carriers so as to prevent solder joint cracking during operation of the system.
Claim 13
Dependent Claim
44 words
The system of claim 10 wherein the effective coefficient of thermal expansion of each bonded wiring board is sufficiently close to that of the carrier so as to prevent solder joint cracking during thermal cycling of the system from -10° C. to 50° C.
Claim 14
Dependent Claim
44 words
The system of claim 10 wherein the effective coefficient of thermal expansion of each bonded wiring board is sufficiently close to that of the carrier so as to prevent solder joint cracking during thermal cycling of the system from -55° C. to 125° C.
Claim 15
Dependent Claim
24 words
The system of claim 10 wherein the ceramic central portion of said substrate is formed of silicon carbide and each metallic layer is aluminum.
Claim 16
Dependent Claim
39 words
The system of claim 10 wherein the ceramic central portion of said substrate is 0.05 in. thick and each metallic layer is 0.0125 in. thick, said substrate having a specific thermal conductivity greater than 4×10 -5 Wm 2 /g°C.
Claim 17
Dependent Claim
20 words
The system of claim 14 wherein said substrate has a specific thermal conductivity of approximately 5.2×10 -5 Wm 2 /g°C.
Claim 18
Dependent Claim
23 words
The system of claim 10 wherein said substrate is characterized by a composite specific thermal conductivity greater than 3×10 -5 Wm 2 /g°C.
Claim 19
Dependent Claim
26 words
The system of claim 10 wherein the metallic layers each comprise one or more metals taken from the group consisting of aluminum, copper, nickel and magnesium.
Claim 20
Dependent Claim
31 words
The system of claim 10 wherein the central portion of said substrate comprises one or more materials taken from the group containing silicon carbide, aluminum nitride, beryllium oxide and boron nitride.
Claim 21
Dependent Claim
29 words
The system of claim 11 wherein the central portion of said substrate comprises a ceramic material formed in combination with a modifier of the type which increases fracture toughness.
Claim 22
Dependent Claim
22 words
The system of claim 19 wherein the ceramic material is 80 percent by volume silicon carbide and the modifier is titanium diboride.
Claim 23
Dependent Claim
44 words
The system of claim 10 wherein one printed wiring board is bonded to each substrate surface, the ceramic central portion is 0.05 in. thick, the total substrate thickness is 0.08 in. and the lowest resonant frequency in the substrate is greater than 460 Hertz.
Claim 24
Dependent Claim
11 words
The system of claim 10 wherein the metal layers comprise aluminum.
Claim 25
Dependent Claim
15 words
The system of claim 10 wherein the metal layers are each an alloy of aluminum.
References Cited (Backward Citations)
US4426423A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-23 | 1994-01-22 | 1994-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-23 | 1998-01-22 | 1998-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-23 | 2002-01-22 | 2002-07-24 | $7700.00 | Window Closed / Lapsed |