US20110132000A1

US20110132000A1 - Thermoelectric Heating/Cooling Structures Including a Plurality of Spaced Apart Thermoelectric Components

Info

Publication number: US20110132000A1
Application number: US12/963,750
Authority: US
Inventors: Philip A. Deane; Edward P. Siivola; Paul Crocco; Ramaswamy Mahadevan
Original assignee: Nextreme Thermal Solutions Inc
Current assignee: Laird Technologies Inc
Priority date: 2009-12-09
Filing date: 2010-12-09
Publication date: 2011-06-09

Abstract

A thermoelectric heating/cooling structure may include a heat exchanger and a heat spreader spaced apart from the heat exchanger. In addition, a plurality of spaced apart thermoelectric components may be thermally coupled in parallel between the heat exchanger and the heat spreader. More particularly, each of the thermoelectric components may include a first header adjacent the heat exchanger, a second header adjacent the heat spreader, and a plurality of thermoelectric elements thermally coupled in parallel between the first and second headers. The first headers of the thermoelectric components may be spaced apart adjacent the heat exchanger, and the second headers of the thermoelectric components may be spaced apart adjacent the heat spreader.

Description

RELATED APPLICATION

The present application claims the benefit of priority from U.S. Provisional Application No. 61/285,001 entitled “Integrating Thermoelectric (TE) Coolers Into Board Level Test Heads” filed Dec. 9, 2009, and from U.S. Provisional Application No. 61/327,463 entitled “Test Head Design” filed Apr. 23, 2010, the disclosures of which are hereby incorporated herein in their entireties by reference.

FIELD OF THE INVENTION

The present invention relates to the field of electronics, and more particularly, to thermoelectric devices and related structures, methods, and systems.

BACKGROUND

Board level functional testing of electronic systems may be performed over a range of temperatures to insure operation when the board is assembled into a final product such as a laptop computer. In order to reduce the duration of board test, localized temperature control of the device under test (DUT) may be accomplished using a thermal test head that makes contact with the device under test. A thermal test head, for example, may be capable of controlling a temperature of the device under test from 0 degrees C. to 100 degrees C. by providing water as a heat exchange fluid through a heat exchanger of the device. Performance, temperature change, and/or temperature range, however, may be limited in such a device.

SUMMARY

According to some embodiments of the present invention, a thermoelectric heating/cooling structure may include a heat exchanger and a heat spreader spaced apart from the heat exchanger. In addition, a plurality of spaced apart thermoelectric components may be thermally coupled in parallel between the heat exchanger and the heat spreader. More particularly, each of the thermoelectric components may include a first header adjacent the heat exchanger, a second header adjacent the heat spreader, and a plurality of thermoelectric elements thermally coupled in parallel between the first and second headers. The first headers of the thermoelectric components may be spaced apart adjacent the heat exchanger, and the second headers of the thermoelectric components may be spaced apart adjacent the heat spreader.
A low melting temperature metal and/or alloy may be thermally coupled between the heat exchanger and each of the first headers of the respective thermoelectric components and/or between the heat spreader and each of the second headers of the respective thermoelectric components. Each of the thermoelectric elements may be bonded between the first and second headers of the respective thermoelectric components using a solder, and the low melting temperature metal and/or alloy may have a melting temperature that is less than a melting temperature of the solder used to bond the thermoelectric components.
The low melting temperature metal and/or alloy may have a melting temperature that is lower than an operating temperature of a surface of the heat exchanger adjacent the thermoelectric components, and the low melting temperature metal and/or alloy may be thermally coupled between the heat exchanger and the first headers. Moreover, the second headers may remain solidly bonded to the heat spreader over operating temperatures of the surface of the heat spreader. The low melting temperature metal and/or alloy, for example, may include a gallium-tin alloy.
A mechanical stand-off structure may be provided between the heat exchanger and the heat spreader with the mechanical stand-off structure being configured to maintain a gap between the heat exchanger and the heat spreader. In addition, a fluid seal may be provided between the heat exchanger and the heat spreader with the fluid seal surrounding the plurality of thermoelectric components. The heat exchanger may include a fluid inlet and a fluid outlet configured to allow heat exchange between a heat exchange fluid and the heat exchanger.
The heat spreader may include a surface spaced apart from the plurality of thermoelectric components with the surface being configured to thermally engage with a device under test. The plurality of thermoelectric components may thus be configured to pump heat between the device under test and the heat exchanger through the heat spreader. Moreover, a servomechanism may be mechanically coupled to the heat exchanger and heat spreader, and the servomechanism may be configured to position the surface of the heat spreader on the device under test during test operations and to remove the surface of the heat spreader from the device under test.
The device under test may be electrically and mechanically coupled to a printed wiring board, and a mounting frame of the thermoelectric heating/cooling structure may be configured to engage portions of the printed wiring board spaced apart from the device under test when the surface of the heat spreader is positioned on the device under test. The mounting frame may define an opening surrounding the heat spreader so that the mounting frame is spaced apart from the heat spreader. In addition, a resilient mechanical coupling may be provided between the mounting frame and the heat spreader, with the resilient mechanical coupling being configured to allow movement of the heat spreader relative to the mounting frame. More particularly, the resilient mechanical coupling may include at least one spring.
The mounting frame may be mechanically fixed to the heat spreader, and the mounting frame may include an opening therethrough to allow thermal contact between the device under test and the heat spreader. More particularly, the mounting frame, the heat spreader, and the heat exchanger may define a sealed enclosure, and/or the mounting frame may be a plastic mounting frame.
By using thermoelectric components to pump heat in a thermal test head having structures discussed herein, improved temperature control and/or a greater range of temperatures may be provided. Moreover, by providing a plurality of separate thermoelectric components between the heat exchanger and the heat spreader together with thermal couplings to the heat exchanger and/or the heat spreader that are liquid at operating temperatures thereof, damage to the thermoelectric components and thermoelectric elements thereof may be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view illustrating a thermoelectric test head according to some embodiments of the present invention.

FIG. 2A is a plan view of thermoelectric components on a heat spreader of FIG. 1 according to some embodiments of the present invention.

FIG. 2B is a plan view of thermoelectric components on a heat spreader of FIG. 1 according to some other embodiments of the present invention.

FIG. 3 is a cross sectional view of a thermoelectric component between a heat exchanger and a heat spreader according to some embodiments of the present invention.

FIG. 4 is a plan view of the frame of FIG. 1 according to some embodiments of the present invention.

FIG. 5 is a cross sectional view illustrating a thermoelectric test head according to some other embodiments of the present invention.

DETAILED DESCRIPTION

The present invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the present invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. Like numbers refer to like elements throughout.
It will be understood that when an element or layer is referred to as being “on”, “connected to” or “coupled to” another element or layer, it can be directly on, connected or coupled to the other element, or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Also, as used herein, “lateral” refers to a direction that is substantially orthogonal to a vertical direction.
The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the present invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
Example embodiments of the present invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a structure illustrated with angular features may instead have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Accordingly, these terms can include equivalent terms that are created after such time. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the present specification and in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.
FIG. 1 is a cross sectional view illustrating a thermoelectric test head according to some embodiments of the present invention. As shown in FIG. 1, a plurality of spaced apart thermoelectric components T may be thermally coupled in parallel between heat exchanger 101 and a high thermal conductivity heat spreader 103. Heat spreader 103, for example, may be formed of a high thermal conductivity metal and/or ceramic.
As shown in greater detail in FIG. 3, each thermoelectric component T may include high thermal conductivity header 301 (e.g., a metal and/or ceramic header) adjacent heat exchanger 101, high thermal conductivity header 303 (e.g., a metal and/or ceramic header) adjacent heat spreader 303, and a plurality of n-type and p-type thermoelectric elements N and P thermally coupled in parallel between first and second headers 301 and 303. Moreover, headers 301 of each thermoelectric component T may be spaced apart adjacent heat exchanger 101, and headers 303 of each thermoelectric component T may be spaced apart adjacent heat spreader 103. Accordingly, thermoelectric components T may be configured to pump heat between heat exchanger 101 and heat spreader 103 responsive to an electrical signal(s) applied thereto.
Heat exchanger 101 may include a fluid inlet 101 a and a fluid outlet 101 b configured to allow heat exchange between a heat exchange fluid (such as water) and the heat exchanger. By providing a heat exchange fluid, heat exchanger 101 may better source/sink heat to/from thermoelectric components T. Accordingly, thermoelectric components T may be configured to pump heat in a first direction from DUT 109 to heat exchanger 101 to cool DUT 109, and to pump heat in a second direction from heat exchanger 101 to DUT 109 to heat DUT 109. Moreover, heat exchanger 101 may be mechanically fixed to support member 105 (e.g., using screws, a permanent adhesive, etc.), and heat spreader 103 may be mechanically fixed to heat exchanger 101, for example, using screws 107. Accordingly, fixed mechanical couplings may be provided between heat spreader 103, heat exchanger 101, and support member 105.
Heat spreader 103 may include a surface spaced apart from thermoelectric components T, and this surface of heat spreader 103 may be configured to thermally engage with device under test (DUT) 109. DUT 109, for example, may be a printed circuit board having a plurality of integrated and/or discrete electronic circuits thereon, or DUT 109 may be an individual integrated circuit on such a circuit board. Moreover, DUT may be electrically and mechanically coupled to printed wiring board (PWB) 111 providing electrical and mechanical connectivity for testing. Accordingly, thermoelectric components T may be configured to pump heat between DUT 109 and heat exchanger 101 through heat spreader 103 to provide temperature control of DUT 109 during functional electrical testing thereof.
As shown in FIG. 1, the thermal test head may be mounted to PWB 111 using positioning screws 115 of servomechanism 116. More particularly, screws 115 may engage with threaded openings of PWB 111 to raise and lower heat spreader 103 (together with heat exchanger 101 and support member 105) relative to DUT 109, Servomechanism 116 may thus be configured to position a surface of the heat spreader 103 on DUT 109 during test operations (to thermally engage heat spreader 103 with DUT 109) and to remove/disengage the surface of heat spreader 103 from DUT 109 after testing. While heat spreader 103 is shown in the raised position in FIG. 1, it will be understood that servomechanism 116 may be configured to lower heat spreader 103 so that a lower surface thereof thermally engages an upper surface of DUT 109.
Servomechanism 116 may thus be configured to lower heat spreader 103 until thermal contact is provided between heat spreader 103 and DUT 109. Electrical operations of DUT 109 may then be activated through PWB 111 to provide electrical/functional testing of DUT 109 while controlling a temperature of DUT 109 by pumping heat through heat spreader 103 to raise and/or lower a temperature of DUT 109 during testing.
In addition, positioning screws 115 may pass through mounting frame 117 and mounting frame may be configured to engage portions of printed wiring board 109 spaced apart from and surrounding DUT 109 when the surface of heat spreader 103 is positioned on the device under test. Mounting frame 117 may define an opening 119 surrounding heat spreader 103 so that mounting frame 117 is spaced apart from heat spreader 103. Opening 119 is further illustrated in the plan view of mounting frame 119 shown in FIG. 4.
Resilient mechanical couplings 121 may also be provided between frame 117 and mounting member 105 to reduce stress on thermoelectric components T when raising and/or lowering the thermal test head. The resilient mechanical couplings 121 may thus be configured to allow movement of heat spreader 103 relative to mounting frame 117. More particularly, resilient mechanical couplings 121 may be implemented as springs provided around each of screws 115 between frame 117 and mounting member 105. While springs are discussed by way of example, other resilient mechanical couplings (e.g., compressible rubber bushings around screws 115 between frame 117 and mounting member 105) may be used.
In addition, a mechanical stand-off structure(s) 123 may be provided between heat exchanger 101 and heat spreader 103, with mechanical stand-off structure(s) 123 being configured to maintain a gap between heat exchanger 101 and heat spreader 103. Mechanical stand-off structure(2) 123, for example, may surround the thermoelectric components T as shown in FIG. 2A, or mechanical stand-off structure(s) 123 may include a plurality of separate elements 123′ spaced around a periphery of thermoelectric components T as shown in FIG. 2B. According to still other embodiments of the present invention, mechanical stand-off structure(s) 123/123′ or portions/elements thereof may be provided between thermoelectric components T. Mechanical stand-off structure(s) 123 may thus reduce compressive force on thermoelectric components T between heat exchanger 101 and heat spreader 103, for example, when heat spreader contacts DUT 109.
In addition, or in an alternative, a resilient gasket 125 may provide a fluid seal between heat exchanger 101 and heat spreader 103, with the fluid seal surrounding the plurality of thermoelectric components T. As shown, screws 107 may pass through gasket 125, and gasket 125 and mechanical stand-off structure(s) 123/123′ may be provided as separate elements. By providing gasket 125 and mechanical stand-off structure 123 as separate elements, each may be formed of a different material(s) providing higher performance for their respective functions. Gasket 125, for example, may be formed of a flexible/resilient material to provide a better fluid seal, while mechanical stand-off structure 123 may be formed of a more rigid material that does not allow significant compression of thermoelectric components T. According to other embodiments of the present invention, a single structure may provide both a fluid seal and a mechanical stand-off.
As shown in greater detail in FIGS. 2A and 2B, thermoelectric components T may be arranged in an array on heat spreader 103. By providing a plurality of relatively small thermoelectric components T (each having its own top and bottom headers) instead of providing one relative large thermoelectric component T, damage due to differences of thermal expansion of hot and cold side headers may be reduced. By providing relatively small thermoelectric components T with relatively small top and bottom headers, absolute differences between linear expansion/contraction of top and bottom headers may be relatively small.
As shown in FIGS. 1 and 3, each thermoelectric component T may be mechanically and thermally coupled to heat exchanger 101 using bonding material(s) 131 and mechanically and thermally coupled to heat spreader 103 using bonding material(s) 133. Moreover, bonding material 131 and/or 133 may be provided using a metal and/or alloy (also referred to as a solder) to provide a solder bond. More particularly, bonding materials 131 and 133 may be provided using different metals/alloys having different melting temperatures.
In particular, one of bonding materials 131 or 133 may be provided using a low melting temperature metal/alloy (e.g., gallium tin solder, indium solder, mercury, etc.) having a melting temperature that is less than an operating temperature of thermoelectric components T (e.g., a melting temperature less than 50 degrees C., or even less than 30 degrees C.), and the other of the bonding materials 131 or 133 may be provided using a higher melting temperature metal/alloy having a melting temperature that is higher than operating temperatures of thermoelectric components T (e.g., a melting temperature greater than 100 degrees C., or even greater than 150 degrees C.). Accordingly, one of the bonding materials 131 or 133 may be liquid at higher operating temperatures of thermoelectric components T while the other of the bonding materials 131 or 133 maintains a solid bond to reduce stress on the thermoelectric components T as heat exchanger 101 and heat spreader expand differently (due to differences in temperature) while maintaining positions of the thermoelectric components T on heat spreader 103. Even when melted, bonding material 131 may provide a high thermal conductivity path between thermoelectric components T and heat exchanger 101. While not shown separately, each bonding material 131 may including barrier and/or adhesion metals on header 301 and on heat exchanger 101, and solder therebetween. Similarly, each bonding material 133 may including barrier and/or adhesion metals on header 303 and on heat spreader 103 and solder therebetween.
Accordingly, to some embodiments of the present invention, the plurality of thermoelectric components T may be soldered to heat spreader 103 using bonding material 133 having a relatively high melting temperature before assembly with heat exchanger 101, servomechanism 116, and/or frame 117. Bonding material 131 having a relatively low melting temperature (e.g., gallium-tin, indium, mercury, etc.) may then be provided on exposed surfaces of thermoelectric components T and/or heat exchanger 101, and heat spreader 103 may then be fastened to heat exchanger 101. At increased operating temperatures when differences between thermal expansions of heat spreader 103 and heat exchanger 101 are greatest, a high thermal conductivity liquid interface provided by melted bonding material 131 may reduce shear (lateral strain) of thermoelectric components T and/or thermoelectric elements thereof. While bonding material 131 is discussed above as having a low melting temperature, according to other embodiments of the present invention, bonding material 133 may have the lower melting temperature (e.g., less than about 50 degrees C. or even less than about 30 degrees C.) while bonding material 131 may have the higher melting temperature (e.g., greater than about 100 degrees C. or even greater than about 150 degrees C.).
As shown in greater detail in FIG. 3, each thermoelectric component T may include a plurality of n-type and p-type thermoelectric elements N and P thermally coupled in parallel between headers 301 and 303, and electrically coupled in series through electrically conductive (e.g., copper) traces 141 and 143. More particularly, thermoelectric elements N and P may be electrically and mechanically coupled to electrically conductive traces 141 and 143 using metal and/or alloy bonding material(s) 151 and 153. Bonding material(s) 151 and 153, for example, may be provided using a solder(s) having a melting temperature that is greater than operating temperatures of thermoelectric components T. More particularly, bonding materials(s) 151 and 153 may have a melting temperature that is greater than a melting temperature of a low melting temperature metal/alloy of bonding material 131 or 133 (e.g., greater than about 100 degrees C. or even greater than about 150 degrees C.). Accordingly, a solid mechanical coupling may be maintained between thermoelectric elements N and P and headers 301 and 303, while a liquid interface is provided between either header 301 and heat exchanger 101 or between header 303 and heat spreader 103. While not shown separately, each bonding material 151 may include barrier and/or adhesion metals on thermoelectric element N/P and on trace 141, and solder therebetween. Similarly, each bonding material 153 may include barrier and/or adhesion metals on thermoelectric element N/P and on trace 143 and solder therebetween.
As shown in FIG. 3, thermoelectric elements N and P and traces 141 and 143 may be arranged so that current flows in opposite directions through n-type thermoelectric elements N and p-type thermoelectric element P to provide a same direction of heat pumping (either from header 301 to header 303 or from header 303 to header 301). While not explicitly shown in FIG. 3, thermoelectric elements N and P and traces 141 and 143 may be arranged in a two dimensional array on headers 301 and 303. For example, 18 n-type thermoelectric elements N and 18 p-type thermoelectric elements may be provided between headers 301 and 303 to provide 18 thermoelectric P-N couples.
Within a thermoelectric component T, all of the P-N couples may be electrically coupled in series or groups of the P-N couples may be electrically coupled in parallel (with couples within a group being electrically coupled in series). Similarly, all of the thermoelectric components T (as shown in FIG. 2A, for example) may be electrically coupled in series, or groups (e.g., rows or columns) of thermoelectric components T may be electrically coupled in parallel (with thermoelectric components T in each group being electrically coupled in series).
FIG. 5 is a cross sectional view illustrating a thermoelectric test head according to some other embodiments of the present invention. The test head of FIG. 5 is similar to that of FIG. 1 except that frame 117′ is mechanically fixed to heat spreader 103, for example, using screws 107′, and frame 117′ is mechanically fixed to support member 105. Thermoelectric components T may thus be confined within an enclosure 161 defined by support member 105, frame 117′, and heat spreader 103. By providing a fixed mechanical coupling between heat spreader 103 and frame 117′ and between frame 117′ and mounting member 105, a direct mechanical coupling between heat spreader 103 and heat exchanger 101 (e.g., using screws 107 of FIG. 1) may be omitted. Accordingly a liquid interface between thermoelectric components T and heat exchanger 101 or heat spreader 103 may be allowed to reduce stresses on thermoelectric components T due to different thermal expansions of heat exchanger 101 and heat spreader 103.
Moreover, enclosure 161 defined by support member 105, frame 117′, and heat spreader 103 may provide sufficient fluid sealing so that a separate gasket 125 between heat exchanger 101 and heat spreader 103 may be omitted. While not shown in FIG. 5, sealing elements (e.g., gaskets) may be provided between frame 117′ and heat spreader 103 and/or between frame 117′ and support member 105.
In the embodiment of FIG. 5, Frame 117′ may be formed of a material, such as plastic, having a relatively low coefficient of thermal expansion. Moreover, a compressive force applied to thermoelectric components T may be reduced and/or controlled by coupling heat spreader 103 to frame 117′. Stated in other words, compressive forces (when heat spreader 103 is brought into contact with DUT 109) may be translated from heat spreader 103 through frame 117′ to support member 105 instead of translating such compressive forces directly through thermoelectric components T.
Because frame 117′ may be in direct contact with heat spreader 103, frame 117′ may be provided using a thermally insulating material, such as plastic, or portions of frame 117′ in direct contact with heat spreader 103 may be provided using a thermally insulating material. According to some other embodiments of the present invention, a thermally insulating layer/gasket may be provided between frame 117′ and heat spreader 103.
As shown in FIG. 5, an opening 119′ through frame 117′ may allow thermal contact between heat spreader 103 and DUT 109. Dimensions of opening 119′, however, may be less than dimensions of heat spreader 103 to allow mechanical coupling therebetween and/or to provide a fluid seal therebetween.
As discussed above with respect to FIG. 1, bonding material 131 or bonding material 133 may be liquid at an operating temperature of the thermoelectric components T to reduce stress resulting from different thermal expansions of heat exchanger 101 and heat spreader 103. Moreover, mechanical stand-off structure(s) 123 may maintain a desired spacing between heat exchanger 101 and heat spreader 103 even when bonding material 131 or bonding material 133 melts during operation. In thermoelectric components T of FIGS. 1, 3, and 5, heat may be pumped from header 301 to header 303 (and thus from heat exchanger 101 to heat spreader 103) responsive to a current through serially coupled p-type and n-type thermoelectric elements P and N thereby heating DUT 109 that is thermally coupled to heat spreader 103. By reversing the current, heat may be pumped from header 303 to header 301 (and thus from heat spreader 103 to heat exchanger 101) responsive to the reversed current thereby cooling DUT 109 that is thermally coupled to heat spreader 103. Thermoelectric structures are discussed, for example, in U.S. Publication Nos. 20060289052 (entitled “Methods Of Forming Thermoelectric Devices Including Conductive Posts And/Or Different Solder Materials And Related Methods And Structures”), 20060289050 (entitled “Methods Of Forming Thermoelectric Devices Including Electrically Insulating Matrixes Between Conductive Traces And Related Structures”), 20060086118 (entitled “Thin Film Thermoelectric Devices For Hot-Spot Thermal Management In Microprocessors And Other Electronics”), 20060289052 (entitled “Methods Of Forming Thermoelectric Devices Including Conductive Posts And/Or Different Solder Materials And Related Methods And Structures”), 20070089773 (entitled “Methods Of Forming Embedded Thermoelectric Coolers With Adjacent Thermally Conductive Fields And Related Structures”), 20070215194 (entitled “Methods Of Forming Thermoelectric Devices Using Islands Of Thermoelectric Material And Related Structures”), 20090000652 (entitled “Thermoelectric Structures Including Bridging Thermoelectric Elements”), and 2009/0072385 (entitled “Electronic Assemblies Providing Active Side Heat Pumping And Related Methods And Structures”), the disclosures of which are hereby incorporated herein in their entirety by reference.
P-type and N-type thermoelectric elements N and P may be provided using semiconductor thin-film deposition techniques, and thermoelectric components T may be fabricated using micro-fabrication techniques. In such thermoelectric components T, a plurality of P and N type thermoelectric elements may be electrically coupled in series (with the series connections alternating between P-type and N-type thermoelectric elements) and thermally coupled in parallel between thermally conductive headers 301 and 303. For example, thin-films of P-type and N-type thermoelectric materials (e.g., bismuth telluride or Bi₂Te₃) may be epitaxially grown on respective substrates and then diced to provide substantially single crystal P-type and N-type thermoelectric elements N and P that are then soldered to respective conductive traces 141 and 143 on header 301 and 303. In an alternative, thermoelectric elements may be provided using bulk (e.g., thicker and non-crystalline) thermoelectric materials.
By using thin-film substantially single crystal thermoelectric elements N and P, a size of a thermoelectric module may be reduced and performance may be improved. Bulk thermoelectric devices, for example, may be limited to about 10 W/cm². Use of thin-film substantially single crystal thermoelectric elements, however, may allow heat pumping capacities of 100 W/cm²or higher. Accordingly, substantially single crystal and/or thin film thermoelectric elements N and P may provide dramatically higher performance than conventional bulk thermoelectric elements, and structures of FIGS. 1-5 may facilitate use of such high performance thermoelectric elements in a test head requiring repeated contact with DUTs without damaging the thermoelectric elements/components.
While the present invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

1. A thermoelectric heating/cooling structure comprising:

a heat exchanger;

a heat spreader spaced apart from the heat exchanger;

a plurality of spaced apart thermoelectric components thermally coupled in parallel between the heat exchanger and the heat spreader, wherein each of the thermoelectric components includes a first header adjacent the heat exchanger, a second header adjacent the heat spreader, and a plurality of thermoelectric elements thermally coupled in parallel between the first and second headers, wherein the first headers of the thermoelectric components are spaced apart adjacent the heat exchanger, and wherein the second headers of the thermoelectric components are spaced apart adjacent the heat spreader.

2. The thermoelectric heating/cooling structure according to claim 1 further comprising:

a low melting temperature metal and/or alloy thermally coupled between the heat exchanger and each of the first headers of the respective thermoelectric components and/or between the heat spreader and each of the second headers of the respective thermoelectric components.

3. The thermoelectric heating/cooling structure according to claim 2 wherein each of the thermoelectric elements is bonded between the first and second headers of the respective thermoelectric component using a solder, wherein the low melting temperature metal and/or alloy has a melting temperature that is less than a melting temperature of the solder used to bond the thermoelectric components.

4. The thermoelectric heating/cooling structure according to claim 2 wherein the low melting temperature metal and/or alloy comprises gallium-tin.

5. The thermoelectric heating/cooling structure according to claim 2 wherein the low melting temperature metal and/or alloy has a melting temperature that is lower than an operating temperature of a surface of the heat exchanger adjacent the thermoelectric components, wherein the low melting temperature metal and/or alloy is thermally coupled between the heat exchanger and the first headers, and wherein the second headers remain solidly bonded to the heat spreader over operating temperatures of the surface of the heat spreader.

6. The thermoelectric heating/cooling structure according to claim 1 further comprising:

a mechanical stand-off structure between the heat exchanger and the heat spreader wherein the mechanical stand-off structure is configured to maintain a gap between the heat exchanger and the heat spreader.

7. The thermoelectric heating/cooling structure according to claim 1 further comprising:

a fluid seal between the heat exchanger and the heat spreader wherein the fluid seal surrounds the plurality of thermoelectric components.

8. The thermoelectric heating/cooling structure according to claim 1 wherein the heat exchanger includes a fluid inlet and a fluid outlet configured to allow heat exchange between a heat exchange fluid and the heat exchanger.

9. The thermoelectric heating/cooling structure according to claim 1 wherein the heat spreader includes a surface spaced apart from the plurality of thermoelectric components, wherein the surface is configured to thermally engage with a device under test.

10. The thermoelectric heating/cooling structure according to claim 9 wherein the plurality of thermoelectric components are configured to pump heat between device under test and the heat exchanger through the heat spreader.

11. The thermoelectric heating/cooling structure according to claim 9 further comprising:

a servomechanism mechanically coupled to the heat exchanger and heat spreader, wherein the servomechanism is configured to position the surface of the heat spreader on the device under test during test operations and to remove the surface of the heat spreader from the device under test.

12. The thermoelectric heating/cooling structure according to claim 11 wherein the device under test is electrically and mechanically coupled to a printed wiring board, the thermoelectric heating/cooling structure further comprising:

a mounting frame configured to engage portions of the printed wiring board spaced apart from the device under test when the surface of the heat spreader is positioned on the device under test.

13. The thermoelectric heating/cooling structure according to claim 12 wherein the mounting frame defines an opening surrounding the heat spreader so that the mounting frame is spaced apart from the heat spreader.

14. The thermoelectric heating/cooling structure according to claim 13 further comprising:

a resilient mechanical coupling between the mounting frame and the heat spreader, wherein the resilient mechanical coupling is configured to allow movement of the heat spreader relative to the mounting frame.

15. The thermoelectric heating/cooling structure according to claim 14 wherein the resilient mechanical coupling comprises at least one spring.

16. The thermoelectric heating/cooling structure according to claim 12 wherein the mounting frame is mechanically fixed to the heat spreader and wherein the mounting frame includes an opening therethrough to allow thermal contact between the device under test and the heat spreader.

17. The thermoelectric heating/cooling structure according to claim 16 wherein the mounting frame, the heat spreader, and the heat exchanger define a sealed enclosure.

18. The thermoelectric heating/cooling structure according to claim 16 wherein the mounting frame comprises a plastic frame.