Method of manufacturing a bonded electrical contact for thermoelectric semiconductor element

• US 3,879,838 A
• Filed: 07/08/1971
• Issued: 04/29/1975
• Est. Priority Date: 03/30/1967
• Status: Expired due to Term

• Current Assignee: Norman C. Miller
• Original Assignee: Norman C. Miller
• Inventors: Miller, Norman C.
• Primary Examiner(s): Lazarus, Richard B.
• Application Number:
  US05/160,941
• Time in Patent Office: 1,391 Days
• Field of Search: 29/502,472.3,569,573,472.9,498,504,492,471.3
• US Class Current: 228/123.1
• CPC Class Codes: H10N 10/82 Connection of interconnections

Abstract

A bonded electrical contact and method for a thermoelectric element. A thin layer of a ductile diffusion barrier, which is non-poisonous to thermoelectric materials, such as iron, tungsten, molybdenum, or niobium, is disposed between the thermoelectric material and a contacting shoe, such as stainless steel, which has poisonous alloy constituents. The thermal expansion coefficient of the diffusion barrier, which does not match that of the thermoelectric material, is overridden by that of the shoe, whose coefficient does correspond with that of such high expansion thermoelectrics as the tellurides.

Claims

1. A METHOD OF BONDING A THERMOELECTRIC MATERIAL TO AN ELECTRICAL SHOE TO FORM A THERMOELECTRIC ARTICLE WHICH COMPRISES:

PROVIDING UPON A SURFACE OF SAID SHOE A THIN ADHERENT LAYER OF A DIFFUSION BARRIER METAL SELECTED FROM THE CLASS CONSISTING OF IRON, TUNGSTEN, MOLYBDENUM, AND NIOBIUM, AND DIFFUSION BONDING A SURFACE OF SAID BARRIER METAL TO A SURFACE OF SAID THERMOELECTRIC MATERIAL AT A COORDINATED ELEVATED TEMPERATURE AND PRESSURE TO FORM SAID THERMOELECTRIC ARTICLE.

2. The method of claim 1 wherein the thermoelectric material is of the telluride class, the diffusion barrier metal is iron, and the shoe or cap is an austenitic stainless steel.

3. The method of claim 1 wherein the thermoelectric material is of the telluride class, the diffusion barrier metal is tungsten, and the shoe or cap is an austenitic stainless steel.

4. The method of claim 1 where the thermoelectric material is of the telluride class, and said diffusion bonding is performed in a hydrogen atmosphere at a temperature of about 1200*-1500*F and at a pressure of about 3000-5000 psi for a period of about 5-30 minutes.

5. The method of claim 1 wherein said diffusion barrier metal is applied in powdered form to said surface of said shoe and then said applied barrier metal is further heated at an elevated temperature below its melting point to promote further agglomeration of the powders prior to diffusion bonding of the resulting assembly.

6. The method of claim 1 wherein said layer of diffusion barrier metal is formed from a powder that has been plasma sprayed onto said surface of said shoe to form a rough surface, and then said barrier metal layer is further heated at an elevated temperature below its melting point in a hydrogen atmosphere.

7. The method of claim 6 wherein the thermoelectric material is of the telluride class, the diffusion barrier metal is iron, and the shoe or cap is an austenitic stainless steel.

8. The method of claim 6 wherein the thermoelectric material is of the telluride class, the diffusion barrier metal is tungsten, and the shoe or cap is an austenitic stainless steel.

9. A method of bonding a thermoelectric material of the telluride class to relatively thick stainless steel shoes to form a thermoelectric article which comprises:

a. plasma spraying a relatively thin layer of a metal in powder form selected from the class consisting of iron, tungsten, molybdenum, and niobium onto one surface of each shoe to form a rough surface, b. further heating the resulting coated shoes in flowing hydrogen at a temperature of about 1800*-1950*F for about 15-45 minutes, c. contacting the resulting shoes with the surfaces of the thermoelectric material, the rough powder metal-containing surface of the shoe facing the thermoelectric material surfaces, and d. diffusion bonding the resulting assembly of thermoelectric material and stainless steel shoes together at a temperature of about 1200*-1500*F at a pressure of about 3000-5000 psi for a period of about 5-30 minutes.

10. The method of claim 9 wherein the stainless steel shoe is about 0.016-0.020 inch thick and is an austenitic stainless steel, and the powder metal layer is about 0.002-0.008 inch thick and is iron.

11. The method of claim 9 wherein the stainless steel shoe is about 0.016-0.02 inch thick and is an austenitic stainless steel, and the powder metal layer is about 0.002-0.008 inch thick and is tungsten.