# US 6,297,441 B1 · Thermoelectric device and method of manufacture

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- Number: US 6,297,441 B1
- Document ID: US6297441B1
- Status: Granted
- Kind: B1
- Application number: 09/535,931
- Filed: 2000-03-24
- Granted: 2001-10-02
- Earliest claimed: 2000-03-24
- Inventors: Chris Macris
- Web page: https://patentgrep.com/patent/US6297441B1

## CPC

- H10N 10/01: Manufacture or treatment
- H10N 10/17: characterised by the structure or configuration of the cell or thermocouple forming the device
- H10W 72/877: {Bump connectors and die-attach connectors}
- H10W 90/724: {between a chip and a stacked insulating package substrate, interposer or RDL}
- Y10S 257/93: Thermoelectric, e.g. peltier effect cooling
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A thermoelectric device containing at least one thermoelement formed by powder metallurgical techniques including, but not limited to: hot pressing, hot isostatic pressing, press and sinter and mechanical alloying.

## Claims

### Claim 1

A thermoelectric device containing at least one thermoelement formed by powder metallurgical techniques wherein each thermoelement has a leg length range, in centimeters, equal to: K+0.026 centimeters to K+0.061 centimeters, wherein K is the thermoelement material's thermal conductivity value, given in watts/centimeter per degree Celsius.

### Claim 2

A thermoelectric device design, providing at least one wafer containing at least two through-hole cavities to accept thermoelements, wherein the wafer thickness is equal to or less than 0.125 centimeters.

### Claim 3 (depends on 2)

A thermoelectric device design, as in claim 2, wherein the wafer is composed of a metallic material.

### Claim 4 (depends on 2)

A thermoelectric device design, as in claim 2, wherein the wafer is composed of a non-ferrous metallic material.

### Claim 5 (depends on 2)

A thermoelectric device design, as in claim 2, wherein the walls of the wafer through-holes are coated with an electrically conductive material.

### Claim 6 (depends on 2)

A thermoelectric device design, as in claim 2, wherein the walls of the wafer cavities are oxidized to mitigate the formation of an intermetallic layer on the thermoelements.

### Claim 7

A method of manufacturing a thermoelectric device, including at least one thermoelement, one heat rejecting interconnection member, one heat absorbing interconnection member, one wafer containing at least two through holes, each containing dissimilar thermoelectric material comprising the steps of:
a. Simultaneously dispensing one type of thermoelectric element material to at least two wafer through holes;
b. Simultaneously cold compacting more than one thermoelement with the wafer;
c. Covering each wafer face with a heat resistant material;
d. Applying hot isostatic pressure to the entire covered wafer;
e. Removing the covering;
f. Cleaning and electrochemically activating the entire wafer surface including the exposed faces of each thermoelement;
g. Plating the entire wafer surface including all exposed faces of each thermoelement;
h. Bonding a metallic sheet to each face of the wafer via the plated layer;
i. Chemically removing part of each metallic sheet and all of the wafer material;
j. Mounting the completed device to a substrate.

### Claim 8 (depends on 7)

A method of manufacture, as in claim 7, wherein the wafer is a metallic material.

### Claim 9 (depends on 7)

A method of manufacture, as in claim 7, wherein the thermoelement material is in powder form.

### Claim 10 (depends on 7)

A method of manufacture as in claim 7, wherein the thermoelement material is in tablet form.

### Claim 11 (depends on 7)

A method of manufacture, as in claim 7, wherein step (a) involves the use of a squeegie for the dispensation of the thermoelement powders.

### Claim 12 (depends on 7)

A method of manufacture, as in claim 7, wherein the step (c) covering is a metallic foil.

### Claim 13 (depends on 7)

A method of manufacturing, as in claim 7, wherein the thermoelement material in step (a) is a mixture of metallic elements which, following step (d) will become the resultant P and N-type thermoelement compounds.

### Claim 14 (depends on 7)

A method of manufacture, as in claim 7, wherein step (d) involves the use of pressureless sintering heat only.

### Claim 15 (depends on 7)

A method of manufacture, as in claim 7, wherein step (g) utilizes a metallic spraying process in lieu of the electroplating and/or metallic sheet in steps (g) and (h) respectively.

### Claim 16 (depends on 7)

A method of manufacture, as in claim 7, which utilizes a conversion coated, anodized substrate.

### Claim 17 (depends on 7)

A method of manufacture as in claim 7, wherein step (i) involves the use of a reusable magnetic mask material comprising a pre-patterned mask which is placed on each face of the wafer to facilitate partial chemical removal of the metallic sheet.

### Claim 18 (depends on 7)

A method of manufacture, as in claim 7, wherein the surface preparation step (f) of each thermoelement for interconnection bonding comprises:
a. Immersion of the thermoelements into an alkaline solution;
b. Making the thermoelements anodic through the application of an external positive polarity voltage to the thermoelements;
c. Completing the electrical circuit within the alkaline solution by applying the external negative voltage polarity to a metallic member, now made cathodic;
d. Removal of thermoelements from the alkaline solution and removal of their remaining surface layer residue chemically.

### Claim 19 (depends on 18)

A method of manufacturing, as in claim 18, wherein the alkaline solution is a solution containing chromic acid.

### Claim 20 (depends on 7)

A method of manufacture, as in claim 7, wherein steps (f) and (g) comprise:
a. Immersion of the thermoelements into an acidic solution;
b. Making the thermoelements cathodic through the application of an external negative polarity voltage to the thermoelements;
c. Completing the electrical circuit within the acidic solution by applying the external positive voltage polarity to a metallic member, now made anodic;
d. Plating a metallic layer on each surface of the thermoelements.

### Claim 21 (depends on 20)

A method of manufacturing, as in claim 20, wherein the acidic solution is a solution containing sulfuric acid.

### Claim 22 (depends on 20)

A method of manufacturing, as in claim 20, where the thermoelement surfaces are subjected to a current density greater than 150 amps per square foot of negatively charged surface area in the solution.

### Claim 23 (depends on 20)

A method of manufacturing, as in claim 20, wherein the electrical potential applied to the thermoelements in steps (a) through (d) is applied prior to immersion of the thermoelements into each solution.

### Claim 24 (depends on 7)

A method of manufacture, as in claim 7, wherein step (g) comprises:
a. Depositing a bismuth layer on each junction face of the P and N-type thermoelements;
b. Melting and solidifying the bismuth layer;
c. Depositing a metallic layer on the bismuth layer.

### Claim 25 (depends on 24)

A method of manufacturing, as in claim 24, wherein step (a) utilizes plating to deposit the bismuth layer.

### Claim 26 (depends on 7)

A method of manufacture, as in claim 7, wherein the completed device in step (j) is subject to:
a. Immersion of the thermoelements into a corrosive solution;
b. Making the thermoelements anodic through the application of an external positive polarity voltage to the thermoelements;
c. Completing the electrical circuit within the corrosive solution by applying the external negative voltage polarity to a metallic member, now made cathodic;
d. Removal of thermoelements from the corrosive solution and removal of their remaining surface layer residue chemically.

### Claim 27 (depends on 26)

A method of manufacturing, as in claim 26, wherein the solution contains chromic acid.

### Claim 28 (depends on 26)

A method of manufacturing, as in claim 26, wherein step (b) polarity is negative and the step (c) polarity is positive.

### Claim 29 (depends on 7)

A method of manufacture, as in claim 7, wherein the thermoelement materials, in powder form, are coated with boric acid prior to thermal processing (sintering, hot pressing, etc.) to getter surface oxides.

### Claim 30

A method of manufacturing a thermoelectric device, including at least one thermoelement, an envelope or covering, one wafer containing at least two through holes, each containing dissimilar thermoelectric material wherein a pressurized liquid or gas is utilized to compact the thermoelements by applying pressure against the envelope which is in direct contact with each thermoelement.

### Claim 31

A method of manufacturing a thermoelectric device, including at least one perforated metallic substrate with two or more through holes each filled with dissimilar thermoelement material in which the completed device is bonded to a perforated metallic substrate.

### Claim 32 (depends on 31)

A method of manufacture, as in claim 31, which utilizes a conversion coated, anodized substrate.

### Claim 33 (depends on 31)

A method of manufacture, as in claim 31, in which the bonding is accomplished through the use of an adhesive.

### Claim 34

A method of manufacturing a thermoelectric device, including at least one thermoelement, one wafer containing at least two through-holes, each containing thermoelement material and at least one sheet of deformable material wherein the wafer and sheet of deformable material are stacked, such that the deformable material interfaces the exposed thermoelement faces, and subjected to heat and pressure, thereby causing the deformable material to deform and compress the thermoelement material into the wafer through-holes.

### Claim 35 (depends on 34)

A method of manufacturing a thermoelectric device, as in claim 34, wherein the sheet of deformable material is comprised of aluminum.

### Claim 36

A method of manufacturing a thermoelectric device, including at least one thermoelement, one wafer containing at least two through-holes, each containing P and N-type thermoelement material wherein both the P and N-type thermoelement materials are hot isostatic pressed simultaneously.

### Claim 37 (depends on 36)

A method of manufacturing a thermoelectric device, as in claim 36, wherein both the P and N-type • thermoelement materials are hot pressed simultaneously.