CN102810626A - Precision machining based manufacturing method of minisize thermoelectric device - Google Patents

Abstract

The invention discloses a micro thermoelectric device manufacturing method based on precision machining, which belongs to the field of micro processing and device integration of functional materials. The core of this process is the production of thermopile (thermoelectric arm array). The specific steps are as follows: first, a series of parallel grooves are processed on the P and N-type thermoelectric block sheets by precision cutting method, and then lubricated with epoxy resin. After being cured, a series of parallel grooves are cut along the direction perpendicular to these grooves and filled with epoxy resin. After recuring and polishing, a two-dimensional array of thermoelectric arms can be produced. Through subsequent electrode fabrication and packaging processes, millimeter-scale micro-thermoelectric devices suitable for portable power supplies or micro-zone cooling can be fabricated.

Description

A method for manufacturing micro-thermoelectric devices based on precision machining

technical field

The invention belongs to the field of micromachining and device integration of functional materials, and in particular relates to a method for manufacturing micro thermoelectric devices based on precision machining.

Background technique

Thermoelectric devices refer to a type of electronic components that can directly realize the mutual conversion of electric energy and thermal energy. Its core is a thermoelectric module composed of multiple groups of thermoelectric materials with different carrier types connected in series and parallel. Compared with traditional internal combustion generators and air compression refrigerators, the main advantages of thermoelectric devices are simple structure, no moving parts (so no vibration and noise), and easy miniaturization and miniaturization; the disadvantage is that in high-power applications, energy The conversion efficiency is relatively low. Miniaturized thermoelectric devices not only have a relative advantage in energy conversion efficiency, but also can be used in the heat dissipation of photoelectric components and electronic chips, as well as micro power supplies based on MEMS (microelectromechanical systems, micro-electromechanical systems) technology, micro-area precise control and biomedicine. and other aspects to obtain new applications.

The basic structure of a thermoelectric device is a thermoelectric arm array composed of several pairs of thermoelectric materials (P-type, N-type) with positive and load carriers connected in series. The output power at work is the sum of the power of P-type and N-type materials. Generally, the manufacturing steps of thermoelectric devices are to first cut the bulk thermoelectric material into the shape of thermoelectric arms, and then arrange them into an array in a P-type and N-type staggered manner. However, this process method encounters two main difficulties in the processing of micro-thermoelectric devices: first, thermoelectric materials usually have low strength and poor processing performance, so the lower limit of the size of the micro-thermoelectric arm and the processing accuracy are limited; Second, even if miniature thermoelectric arms are processed, arranging them regularly requires high process and labor costs. And the present invention can better solve these problems.

Contents of the invention

The purpose of the present invention is to provide a method for manufacturing micro-thermoelectric devices based on precision machining. Its main feature is that the processing of thermoelectric arms and the arrangement of arrays are realized synchronously through cutting-insertion compounding-re-cutting, which saves process and Labor costs. At the same time, since the thermoelectric sheet is supported and protected by the epoxy resin during the second cutting, the thermoelectric arm can obtain a higher degree of miniaturization and processing accuracy.

A method for manufacturing a micro-thermoelectric device based on precision machining, the method comprising the steps of:

(1) First use the precision cutting method to process a series of parallel grooves on the surface of the P-type and N-type thin thermoelectric block materials, and then insert and compound the P-type and N-type thin pieces under the lubrication of epoxy resin. And carry out curing treatment to obtain composite sheet;

(2) Polish one of the surfaces of the composite sheet, and then cut a series of parallel grooves on this surface along the direction perpendicular to the cutting direction of step (1), and fill it with epoxy resin, and form a micro thermoelectric arm after curing array;

(3) Fabricate electrodes connected in series with thermoelectric arm arrays, and package them into miniature thermoelectric devices.

The thickness of the P-type and N-type sheet-shaped thermoelectric block materials is 1-2 mm.

Adopt same epoxy resin in step (1) and (2), the epoxy value of epoxy resin is 35～45.

In step (1), the depth of the grooves is 0.3-1 mm, the width is 50-200 microns, and the distance between them is 80%-90% of the width of the grooves.

During polishing in step (2), the composite sheet is generally polished until the P-type and N-type intercalation composite parts are exposed.

In step (2), the depth of the grooves is 0.3-0.8 mm, the width is 50-500 microns, and the interval is 50-500 microns.

In step (1) and step (2), the curing time is more than 24 hours.

The fabrication of the electrodes in step (3) includes the following steps: polishing a surface of the thermoelectric arm array, and then using ultraviolet lithography to make a photoresist mask on the surface, and then using plasma etching to etch The exposed part of the mask is then used to make electrodes on this surface by magnetron sputtering; use the same method to make electrodes on the other side of the thermoelectric arm array.

The electrode is a nickel-copper composite film, wherein the nickel is on the bottom layer (close to the thermoelectric arm), and the thickness is 0.1-0.5 microns; the copper is on the surface layer, and the thickness is 3-10 microns; the shape of the electrode is a square, and the side length is equal to step (1) The distance between the grooves cut in the middle.

The resin composite step plays a key role in the manufacturing method. First of all, during the cutting process, the resin plays a role in positioning and improving the strength of the thermoelectric arm: this enables the cutting and array arrangement of the thermoelectric arm to be completed at one time, and due to the filling and bonding of the resin during step (2) cutting It is easy to cut out intact high aspect ratio thermoelectric arms. Secondly, in the use of the device, since the resin is a good insulator of electricity and heat (about 1/6 of the thermoelectric material), the presence of the resin will basically not affect the energy conversion power and efficiency of the device, but may improve the overall flexibility of the device. degree and reliability.

The beneficial effects of the present invention are: the processing of the thermoelectric arms and the arrangement of the arrays are realized synchronously through cutting-insertion compounding-re-cutting, the operation is simple, and the process and labor costs are saved; Support and protection, so the thermoelectric arm can obtain a higher degree of miniaturization and processing accuracy, the miniaturization degree of the cross-section of the thermoelectric arm can reach less than 100 microns, the machining accuracy error can reach less than 10 microns, and the aspect ratio of the thermoelectric arm can reach more than 3 , the highest integration level of the device reaches more than 10,000 thermoelectric arms per square centimeter.

Description of drawings

Fig. 1 is the main production flow chart of the present invention: (a) P-type, N-type flakes with grooves processed on the surface, (b) obtained surface after polishing one side of P-type and N-type composite flakes, (c) The surface obtained after polishing one side of the micro-thermoelectric arm array, (d) the A-side electrode made, (e) the B-side electrode made;

Fig. 2 is the fabrication process of electrodes used to connect micro-thermoelectric arm arrays in series;

Figure 3 is an optical micrograph of fabricated thermoelectric arm arrays of different scales;

Fig. 4 is the optical micrograph of the thermoelectric arm array and connection electrode of the miniature thermoelectric device that makes;

Figure 5 High magnification microscopic morphology of the electrode part.

Detailed ways

The present invention will be further described in detail through specific examples below, but the content of the present invention is not limited to the content involved in the examples.

The present invention is mainly realized through two steps: the first step is to use the method of cutting-inserting compound-re-cutting to make epoxy resin composite micro-thermoelectric arm arrays; the second step is to use ultraviolet lithography, plasma etching and magnetron Micromachining methods such as sputtering are used to fabricate electrodes connected in series to thermoelectric arms.

Concrete preparation process is as follows:

(1) As shown in Figure 1, use a precision dicing machine to cut out two pieces of P-type and N-type sheet-shaped thermoelectric block materials with a thickness of 1-2 mm, each with a depth of 0.3-1 mm and a width of 50-50 mm. 200 microns, a series of parallel grooves with an interval of 80% to 90% of the width. The interval between the grooves is slightly smaller than the width of the groove. Under the lubricating effect of the epoxy resin, they are intercalated and compounded, and cured for more than 24 hours to obtain composite sheets of P-type and N-type thermoelectric materials.

(2) One of the surfaces of the composite sheet is polished to expose the P-type and N-type intercalation composite parts, and then cut on this surface along the direction perpendicular to the last cutting direction with a depth of 0.3 to 0.8 mm and a width of 50 to 50 mm. A series of parallel grooves with a thickness of 500 microns and an interval of 50-500 microns are filled with the same epoxy resin as in step (1) and cured for more than 24 hours to form a miniature thermoelectric arm array.

(3) As shown in Figure 2, polish one surface of the thermoelectric arm array (thermopile) composited with the resin, coat the photosensitive glue, and obtain the pattern of the A-side electrode through exposure and development, and use argon plasma bombardment to clean the surface , and then magnetron sputtering nickel-copper composite electrodes, using the wet stripping process to remove the photoresist, and packaging the A side with resin and silicon wafer; using the same method to make the B side electrode, and packaging, you can make a suitable Millimeter-scale miniature thermoelectric devices for portable power sources or micro-zone cooling.

Among them, the nickel layer of the nickel-copper composite electrode is in contact with the thermoelectric material, with a thickness of 0.1 to 0.5 microns, which is used to improve the adhesion between the electrode and the material, and to prevent copper from diffusing into the thermoelectric material. The thickness of the copper is 3 to 10 microns , the role is to provide high conductivity.

Example 1

(1) Use a precision dicing machine to cut a series of parallel grooves with a depth of 0.6 mm, a width of 200 microns, and a mutual interval of 180 microns on the surface of the P-type and N-type thin thermoelectric block materials with a thickness of 2 mm. , and then intercalated and compounded under the lubrication of epoxy resin (epoxy value 44), and cured for 24 hours to obtain composite sheets of P-type and N-type thermoelectric materials.

(2) One of the surfaces of the composite sheet is polished to expose the P-type and N-type intercalation composite parts (polished thickness is 1.4 mm), and then cut along the direction perpendicular to the cutting direction in step (1) on this surface A series of parallel grooves with a depth of 0.6 mm, a width of 200 microns, and an interval of 400 microns were filled in and cured for 24 hours with epoxy resin (epoxy value 44) to form a miniature thermoelectric arm array, as shown in Figure 3 ( a) as shown.

(3) Polish a surface of the thermoelectric arm array composited with the resin, coat the photosensitive adhesive, and obtain the pattern of the electrode on the A side through exposure and development, use argon plasma bombardment to clean the surface, and then magnetron sputtering nickel-copper composite For the electrode, the photoresist is removed by wet stripping process, and the A side is packaged with resin and silicon wafer; the electrode of the B side is made by the same method, and packaged into a micro thermoelectric device. Wherein, the side length of the fabricated nickel-copper composite series electrode is 0.18 mm, the thickness of the nickel layer is 0.2-0.25 microns, and the thickness of the copper layer is 7-7.5 microns.

Example 2

(1) Use a precision dicing machine to cut a series of parallel grooves with a depth of 0.5 mm, a width of 100 microns, and a mutual interval of 80 microns on the surface of the P-type and N-type thin thermoelectric block materials with a thickness of 2 mm. , and then intercalated and compounded under the lubrication of epoxy resin with an epoxy value of 44, and cured for more than 24 hours to obtain composite sheets of P-type and N-type thermoelectric materials.

(2) Polish one of the surfaces of the composite sheet to expose the P-type and N-type intercalation composite parts, and then cut out a depth of 0.4 mm and a width of 150 microns along the direction perpendicular to the last cutting direction on this surface, with an interval of It is a 200 micron groove, and filled with the same epoxy resin and cured for more than 24 hours to form a micro thermoelectric arm array, as shown in Figure 3(b).

(3) Polish a surface of the thermoelectric arm array composited with the resin, coat the photosensitive adhesive, and obtain the pattern of the electrode on the A side through exposure and development, use argon plasma bombardment to clean the surface, and then magnetron sputtering nickel-copper composite For the electrode, the photoresist is removed by a wet stripping process, and the A side is packaged with resin and silicon wafer; the electrode of the B side is made and packaged by the same method. Wherein, the side length of the fabricated nickel-copper composite series electrode is 0.08 mm, the thickness of the nickel layer is 0.4-0.45 microns, and the thickness of the copper layer is 6-6.5 microns.

Example 3

(1) Use a precision dicing machine to cut a series of parallel grooves with a depth of 0.8 mm, a width of 200 microns, and a mutual interval of 170 microns on the surface of the P-type and N-type thin thermoelectric block materials with a thickness of 1.5 mm. , and then intercalated and compounded under the lubrication of epoxy resin with an epoxy value of 36, and cured for more than 24 hours to obtain composite sheets of P-type and N-type thermoelectric materials.

(2) One of the surfaces of the composite sheet is polished to expose the P-type and N-type intercalation composite parts, and then cut on this surface along the direction perpendicular to the previous cutting direction with a depth of 0.7 mm and a width of 200 microns. The grooves are 400 microns, filled with epoxy resin with an epoxy value of 36 and cured for more than 24 hours to form a micro thermoelectric arm array (Fig. 4(a), (b)).

(3) Polish a surface of the thermoelectric arm array (thermopile) composited with the resin, coat the photosensitive adhesive, and obtain the pattern of the electrode on the A side by exposure and development, use argon plasma bombardment to clean the surface, and then sputter nickel- For the copper composite electrode, the photoresist is removed by the wet stripping process, and the A side is packaged with resin and silicon wafer; the electrode of the B side is made by the same method, and packaged into a micro thermoelectric device.

The fabricated nickel-copper composite series electrode (Fig. 4(c), (d)) has a side length of 170 microns, a nickel layer thickness of 0.35-0.4 microns, and a copper layer thickness of 4-4.5 microns. Each thermoelectric arm has a cross-sectional area of 0.07 square millimeters and a length of 0.6 millimeters. Figure 5 shows the local high-magnification microscopic morphology of a single electrode.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. one kind based on precision machined minisize thermoelectric device manufacture method, and it is characterized in that: this method comprises the steps:

(1) utilizes the precise cutting method to process the series of parallel groove at P type, the laminar thermoelectric block body material of N type on the surface respectively earlier, make the slotting embedding of P type and N type thin slice compound down at the lubricated of epoxy resin then, and carry out cured, obtain compound foil;

(2) with one of them surface finish of compound foil, on this surface, the edge cuts out the series of parallel groove with the vertical direction of step (1) cut direction, and inserts epoxy resin then, solidifies the back and forms minisize thermoelectric arm array;

(3) make the electrode of thermoelectric arm that is connected in series, and be packaged into the minisize thermoelectric device.

2. method according to claim 1 is characterized in that: the thickness of described P type and the laminar thermoelectric block body material of N type is 1～2 millimeter.

3. method according to claim 1 is characterized in that: the degree of depth of the described groove of step (1) is 0.3～1 millimeter, and width is 50～200 microns, and the space distance is 80%～90% of a recess width.

4. method according to claim 1 is characterized in that: will compound foil be polished to the slotting embedding composite portion of exposing P type and N type when polishing in the step (2).

5. method according to claim 1 is characterized in that: the degree of depth of the described groove of step (2) is 0.3～0.8 millimeter, and width is 50～500 microns, is spaced apart 50～500 microns.

6. method according to claim 1 is characterized in that: step (1) and the identical epoxy resin of the middle employing of step (2), the epoxide number of epoxy resin is 35～45.

7. method according to claim 1 is characterized in that: in step (1) and the step (2), be more than 24 hours curing time.

8. method according to claim 1; It is characterized in that: the making of electrode described in the step (3) comprises the steps: the wherein one side surface finish with the thermoelectric arm array; Utilize the method for ultraviolet photolithographic on this surface, to produce the mask of photoresist then; Utilize the part of exposing in the method etching mask of plasma etching again, utilize the method for magnetron sputtering to produce this lip-deep electrode subsequently; Profit uses the same method and makes the electrode of thermoelectric arm array another side.

9. method according to claim 1 is characterized in that: electrode is nickel-copper laminated film, and nickel is at bottom, and thickness is 0.1～0.5 micron, and copper is on the top layer, and thickness is 3～10 microns.

10. according to claim 1,8 or 9 described methods, it is characterized in that: electrode be shaped as square, the length of side equals the groove interval each other of cutting in the step (1).

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