# US 7,743,763 B2 · Structurally isolated thermal interface

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- Number: US 7,743,763 B2
- Document ID: US7743763B2
- Status: Granted
- Kind: B2
- Application number: 11/829,456
- Filed: 2007-07-27
- Published: 2009-01-29
- Granted: 2010-06-29
- Earliest claimed: 2007-07-27
- Assignees: The Boeing Company
- Inventors: Robert E. Grip; Blaine K. Rawdon; Gurpreet S. Jalewalia
- Web page: https://patentgrep.com/patent/US7743763B2

## CPC

- H10F 77/63: Arrangements for cooling directly associated or integrated with photovoltaic cells, e.g. heat sinks directly associated with the photovoltaic cells or integrated Peltier elements for active cooling
- Y02E 10/50: Photovoltaic [PV] energy
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

In one embodiment, an assembly having bodies of different thermal expansion rates comprises a first body, a second body having a different thermal expansion rate than the first body, and a plurality of high conductivity members attached to both the first and second bodies. The high conductivity members are more flexible than the first and second bodies in order to allow for varied thermal expansion of the first and second bodies. The assembly may comprise a solar collector assembly, wherein the first body is a solar cell attached to a substrate, and the second body is a heat sink.

## Claims

### Claim 1

A heat conducting assembly comprising:
a first body and a second body;
a plurality of high conductivity members attached to both the first and second bodies, wherein the high conductivity members are more flexible than the first and second bodies in order to allow for varied thermal expansion of the first and second bodies;
and at least one of the following:
(1) the plurality of high conductivity members are more flexible in lateral X and Y directions than the first and second bodies in order to produce a low bending stiffness, wherein the lateral X and Y directions extend laterally along the first and second bodies, and the plurality of high conductivity members are more stiff in the Z direction than the first and second bodies, wherein the Z direction extends between the first and second bodies perpendicular to the lateral X and Y directions; and
(2) the plurality of high conductivity members vary symmetrically from being largest near a center of the first and second bodies to being smallest at perimeters of the first and second bodies.

### Claim 2 (depends on 1)

The assembly of claim 1 wherein the first and second bodies have different thermal rates of expansion.

### Claim 3 (depends on 1)

The assembly of claim 1 wherein the assembly is a solar collector assembly.

### Claim 4 (depends on 1)

The assembly of claim 1 wherein the first body comprises a substrate attached to a solar cell.

### Claim 5 (depends on 4)

The assembly of claim 4 wherein the substrate is made of Alumina and the solar cell is made of Germanium.

### Claim 6 (depends on 1)

The assembly of claim 1 wherein the second body comprises a heat sink.

### Claim 7 (depends on 6)

The assembly of claim 6 wherein the heat sink is made of Copper.

### Claim 8 (depends on 1)

The assembly of claim 1 wherein one end of each high conductivity member is soldered to the first body and a second end of each high conductivity member is soldered to the second body.

### Claim 9 (depends on 1)

The assembly of claim 1 wherein the high conductivity members comprise wires.

### Claim 10 (depends on 1)

The assembly of claim 1 wherein the high conductivity members are long and thin.

### Claim 11 (depends on 1)

The assembly of claim 1 wherein the high conductivity members are made of Copper.

### Claim 12 (depends on 1)

The assembly of claim 1 wherein the high conductivity members are more flexible in the lateral X and Y directions than the first and second bodies.

### Claim 13 (depends on 1)

The assembly of claim 1 wherein the high conductivity members have at least one of rectangular, hexagonal, and square cross-sections.

### Claim 14 (depends on 1)

The assembly of claim 1 wherein the high conductivity members are attached to at least one additional body.

### Claim 15 (depends on 1)

The heat conducting assembly of claim 1 wherein the plurality of high conductivity members comprise varying diameters with the diameters of the high conductivity members varying from being largest near the center of the first and second bodies to being smallest at the perimeters of the first and second bodies.

### Claim 16 (depends on 1)

The heat conducting assembly of claim 1 wherein the plurality of high conductivity members are more flexible in the lateral X and Y directions than the first and second bodies in order to produce the low bending stiffness, and the plurality of high conductivity members are more stiff in the Z direction than the first and second bodies.

### Claim 17 (depends on 1)

The high conducting assembly of claim 1 wherein the plurality of high conductivity members are more thermally conductive in the Z direction than in the lateral X and Y directions.

### Claim 18 (depends on 1)

The high conducting assembly of claim 1 wherein the plurality of high conductivity members are non-uniformly spaced.

### Claim 19 (depends on 1)

The heat conducting assembly of claim 1 wherein the plurality of high conductivity members have varying sized cross-sections.

### Claim 20 (depends on 1)

The heat conducting assembly of claim 1 wherein the plurality of high conductivity members have varying lengths.

### Claim 21 (depends on 1)

The heat conducting assembly of claim 1 wherein the plurality of high conductivity members have varying shapes.

### Claim 22 (depends on 1)

The heat conducting assembly of claim 1 wherein the plurality of high conductivity members symmetrically vary from being largest near the center of the first and second bodies to being smallest at the perimeters of the first and second bodies.

### Claim 23 (depends on 22)

The heat conducting assembly of claim 22 wherein the plurality of high conductivity members continuously and symmetrically vary from being largest near the center of the first and second bodies to being smallest at the perimeters of the first and second bodies.

### Claim 24

A solar collector assembly comprising:
a solar cell;
a heat sink which has a different thermal expansion rate than the solar cell; and a plurality of high conductivity members attached between the solar cell and the heat sink for transferring heat from the solar cell to the heat sink while compensating for thermal expansion differences between the solar cell and the heat sink;
and at least one of the following:
(1) the plurality of high conductivity members are more flexible in lateral X and Y directions than the solar cell and the heat sink in order to produce a low bending stiffness, wherein the lateral X and Y directions extend laterally along the solar cell and the heat sink, and the plurality of high conductivity members are more stiff in the Z direction than the solar cell and the heat sink, wherein the Z direction extends between the solar cell and the heat sink perpendicular to the lateral X and Y directions; and
(2) the plurality of high conductivity members vary symmetrically from being largest near a center of the solar cell and the heat sink to being smallest at perimeters of the solar cell and the heat sink.

### Claim 25 (depends on 24)

The solar collector assembly of claim 24 wherein the solar cell is made of Germanium and the heat sink is made of Copper.

### Claim 26 (depends on 24)

The solar collector assembly of claim 24 wherein one end of each high conductivity member is attached to a substrate which is attached to the solar cell and a second end of each high conductivity member is attached to the heat sink.

### Claim 27 (depends on 26)

The solar collector assembly of claim 26 wherein the high conductivity members are soldered to the substrate and the heat sink.

### Claim 28 (depends on 24)

The solar collector assembly of claim 24 wherein the high conductivity members are more flexible than the solar cell and the heat sink in order to allow for varied thermal expansion of the solar cell and the heat sink.

### Claim 29 (depends on 28)

The solar collector assembly of claim 28 wherein the high conductivity members are more flexible in the lateral X and Y directions than the solar cell and the heat sink.

### Claim 30 (depends on 24)

The solar collector assembly of claim 24 wherein the high conductivity members comprise wires.

### Claim 31 (depends on 30)

The solar collector assembly of claim 30 wherein the wires are long and thin.

### Claim 32 (depends on 24)

The solar collector assembly of claim 24 wherein the high conductivity members are made of Copper.

### Claim 33 (depends on 24)

The solar collector assembly of claim 24 wherein the high conductivity members have at least one of rectangular, hexagonal, and square cross-sections.

### Claim 34 (depends on 24)

The solar collector assembly of claim 24 wherein the high conductivity members are attached to at least one additional body.

### Claim 35 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members comprise varying diameters with the diameters of the high conductivity members varying from being largest near the center of the solar cell and the heat sink to being smallest at the perimeters of the solar cell and the heat sink.

### Claim 36 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members are more flexible in the lateral X and Y directions than the solar cell and the heat sink in order to produce the low bending stiffness, and the plurality of high conductivity members are more stiff in the Z direction than the solar cell and the heat sink.

### Claim 37 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members are more thermally conductive in the Z direction than in the lateral X and Y directions.

### Claim 38 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members are non-uniformly spaced.

### Claim 39 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members have varying sized cross-sections.

### Claim 40 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members have varying lengths.

### Claim 41 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members have varying shapes.

### Claim 42 (depends on 24)

The solar collector assembly of claim 24 wherein the plurality of high conductivity members symmetrically vary from being largest near the center of the solar cell and the heat sink to being smallest at the perimeters of the solar cell and the heat sink.

### Claim 43 (depends on 42)

The solar collector assembly of claim 42 wherein the plurality of high conductivity members continuously and symmetrically vary from being largest near the center of the solar cell and the heat sink to being smallest at the perimeters of the solar cell and the heat sink.

### Claim 44

A method of reducing at least one of stress and strain of a solar cell comprising:
providing a solar collector assembly comprising a solar cell and a heat sink, wherein the heat sink has a different thermal expansion rate than the solar cell;
attaching a plurality of high conductivity members between the solar cell and the heat sink with at least one of the following: (1) the plurality of high conductivity members being more flexible in lateral X and Y directions than the solar cell and the heat sink in order to produce a low bending stiffness, wherein the lateral X and Y directions extend laterally along the solar cell and the heat sink, and the plurality of high conductivity members being more stiff in the Z direction than the solar cell and the heat sink, wherein the Z direction extends between the solar cell and the heat sink perpendicular to the lateral X and Y directions; and (2) the plurality of high conductivity members varying symmetrically from being largest near a center of the solar cell and the heat sink to being smallest at perimeters of the solar cell and the heat sink;
heating the solar cell; and
transferring heat from the solar cell through the high conductivity members to the heat sink, wherein during the transfer of heat portions of the high conductivity members close to the heat sink move at least one of more and less than portions of the high conductivity members close to the solar cell to compensate for the thermal expansion differences between the solar cell and the heat sink.

### Claim 45 (depends on 44)

The method of claim 44 wherein the solar cell is made of Germanium and the heat sink is made of Copper.

### Claim 46 (depends on 44)

The method of claim 44 wherein during the attaching step one end of each high conductivity member is attached to a substrate which is attached to the solar cell and a second end of each high conductivity member is attached to the heat sink.

### Claim 47 (depends on 46)

The method of claim 46 wherein during the attaching step the high conductivity members are soldered to the substrate and the heat sink.

### Claim 48 (depends on 44)

The method of claim 44 wherein the high conductivity members are more flexible than the solar cell and the heat sink.

### Claim 49 (depends on 48)

The method of claim 48 wherein the high conductivity members are more flexible in the lateral X and Y directions than the solar cell and the heat sink.

### Claim 50 (depends on 44)

The method of claim 44 wherein the high conductivity members comprise long and thin wires.

### Claim 51 (depends on 44)

The method of claim 44 wherein the high conductivity members are made of Copper.

### Claim 52 (depends on 44)

The method of claim 44 wherein the high conductivity members have at least one of rectangular, hexagonal, and square cross-sections.

### Claim 53 (depends on 44)

The method of claim 44 further comprising the step of attaching the high conductivity members to at least one additional body.

### Claim 54 (depends on 44)

The method of claim 44 wherein the plurality of high conductivity members comprise varying diameters, and the attaching comprises attaching the high conductivity members having the largest diameters near the center of the solar cell and the heat sink and attaching the high conductivity members having the smallest diameters at the perimeters of the solar cell and the heat sink.

### Claim 55 (depends on 44)

The method of claim 44 wherein the plurality of attached high conductivity members are more flexible in the lateral X and Y directions than the solar cell and the heat sink in order to produce the low bending stiffness, and the plurality of attached high conductivity members are more stiff in the Z direction than the solar cell and the heat sink.

### Claim 56 (depends on 44)

The method of claim 44 wherein the plurality of attached high conductivity members are more thermally conductive in the Z direction than in the lateral X and Y directions.

### Claim 57 (depends on 44)

The method of claim 44 wherein the plurality of attached high conductivity members are non-uniformly spaced.

### Claim 58 (depends on 44)

The method of claim 44 wherein the plurality of high conductivity members have varying sized cross-sections.

### Claim 59 (depends on 44)

The method of claim 44 wherein the plurality of high conductivity members have varying lengths.

### Claim 60 (depends on 44)

The method of claim 44 wherein the plurality of high conductivity members have varying shapes.

### Claim 61 (depends on 44)

The method of claim 44 wherein the attaching comprises symmetrically attaching the high conductivity members which are largest near the center of the solar cell and the heat sink and attaching the high conductivity members which are smallest at the perimeters of the solar cell and the heat sink.

### Claim 62 (depends on 44)

The method of claim 44 wherein the attaching comprises continuously and symmetrically attaching the high conductivity members which are largest near the center of the solar cell and the heat sink and attaching the high conductivity members which are smallest at the perimeters of the solar cell and the heat sink.