Preparation method of flexible semiconductor chilling plate

Abstract

The invention discloses a preparation method of a flexible semiconductor chilling plate, which belongs to the technical field of semiconductor chilling, and comprises the following steps: solder paste printing: printing first solder paste on one surface of a first flexible substrate, and printing second solder paste on one surface of a second flexible substrate; first-time surface mounting: mounting one surface of the semiconductor crystal grain to the first solder paste of the first flexible substrate; first reflow soldering: performing first reflow soldering solidification on the semiconductor crystal grains and the first flexible substrate; a second time of surface mounting: a second flexible substrate is mounted on the semiconductor crystal grain of the first flexible substrate after the first time of reflow soldering, and the other surface of the semiconductor crystal grain is mounted on the second solder paste; second reflow soldering: performing second reflow soldering solidification on the first flexible substrate and the second flexible substrate; and cutting the substrate: cutting the second flexible substrate into a plurality of second sub-substrates which are completely disconnected or partially connected. The flexible semiconductor chilling plate prepared by the invention can be attached to various mounting surfaces with complex shapes.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor refrigeration, in particular to a method for preparing a flexible semiconductor refrigeration sheet. Background Art

[0002] Semiconductor cooling technology, based on the Peltier effect, is an advanced temperature control method. Its core principle is to utilize the unique properties of thermoelectric semiconductor materials to achieve cooling. The operating mechanism of this technology is that when a direct current flows through the junction between the thermoelectric material and the electrode, it induces an endothermic effect at one end of the thermoelectric material, thereby achieving cooling. Simultaneously, a corresponding endothermic effect occurs at the other end, achieving heating. Due to its high efficiency and environmentally friendly features, semiconductor cooling technology has shown broad application potential in numerous scientific and industrial fields. However, despite its many advantages, semiconductor cooling technology still faces some challenges in practical application. Currently, semiconductor cooling chips are typically constructed by placing substrates at opposite ends of a semiconductor particle assembly. This structure allows cooling at one end of the semiconductor cooling chip and heating at the other end. Existing semiconductor cooling chips mostly use substrates made of rigid materials such as ceramic sheets. While this rigid substrate design provides a certain degree of structural strength and stability for the semiconductor cooling chip, it also limits its application flexibility. Especially when facing installation environments with complex and changing shapes, such as curved, spherical, or other irregular surfaces, rigid-based semiconductor cooling chips often have difficulty achieving a tight and uniform fit. This lack of fit not only significantly reduces the cooling effect but can also cause physical damage to the cooling chip due to stress concentration, thus limiting the application and expansion of semiconductor cooling technology in more fields.

[0003] Therefore, the above technical problems need to be solved. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention proposes a method for preparing a flexible semiconductor refrigeration sheet. The refrigeration sheet prepared by this method can be bent according to the shape of the installation surface to achieve better fitting.

[0005] In order to solve the above technical problems, the present invention discloses a method for preparing a flexible semiconductor refrigeration sheet, comprising the following steps:

[0006] Solder paste printing: printing a first solder paste on one side of the first flexible substrate, and printing a second solder paste on one side of the second flexible substrate;

[0007] First patching: attaching one side of a semiconductor die to the first solder paste of the first flexible substrate, wherein a plurality of semiconductor die are provided and arranged in a matrix;

[0008] First reflow: The semiconductor die and the first flexible substrate that have been completed by the first patch are subjected to the first reflow curing;

[0009] Second patching: The second flexible substrate is attached to the semiconductor die of the first flexible substrate that has completed the first reflow, so that the other side of the semiconductor die arranged in a matrix is attached to the second solder paste area of the second flexible substrate;

[0010] Second reflow soldering: The first flexible substrate and the second flexible substrate after mounting are subjected to a second reflow soldering and curing process;

[0011] Cutting the substrate: cutting the second flexible substrate into a plurality of second sub-substrates that are completely disconnected or partially connected.

[0012] Furthermore, in the step of cutting the substrate, the first flexible substrate is cut into a plurality of first sub-substrates, and two adjacent first sub-substrates are at least partially connected together.

[0013] Furthermore, the semiconductor grains are made of semiconductor materials, and the semiconductor materials are N-type and P-type semiconductor materials, including one or more of bismuth telluride, silicon, germanium, silicon-germanium alloy, and silicon carbide.

[0014] Furthermore, the semiconductor grains include N-type grains and P-type grains. In the first mounting step, the mounting method adopted is solid crystal or SMT mounting. The N-type grains and P-type grains are arranged in an alternating manner, and the number of N-type grains and P-type grains is the same.

[0015] Furthermore, the method further comprises the following steps:

[0016] Wire bonding: welding wires for connecting to an external power source on the first flexible substrate and / or the second flexible substrate;

[0017] Glue dispensing: Spray glue between the first flexible substrate and the second flexible substrate after the wire bonding is completed.

[0018] Furthermore, the first flexible substrate and the second flexible substrate are films made of polyimide material.

[0019] Furthermore, before the solder paste printing step, multiple heat transfer plates are mounted on the side of the first flexible substrate where the first solder paste is not printed, and multiple heat transfer plates are mounted on the side of the second flexible substrate where the second solder paste is not printed.

[0020] Furthermore, the second sub-substrate is cut into an annular shape or a circular shape, and a plurality of second sub-substrates form a concentric circle structure.

[0021] Furthermore, a heat transfer plate having the same shape as the second sub-base plate is mounted on each second sub-base plate.

[0022] Furthermore, the heat transfer plate is a thermally conductive metal, a ceramic material, or a ceramic material with a thermally conductive metal plated on the surface. The thermally conductive metal includes one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, and silver-copper-aluminum alloy. The ceramic material includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

[0023] The beneficial effect of the present invention is that the flexible semiconductor refrigeration sheet prepared by the method can be bent according to the actual installation surface and can be fitted to installation surfaces of various complex shapes, thereby enhancing adaptability and application range.

[0024] The technical solution of the present invention is to create gaps between multiple second flexible substrates by cutting the second flexible substrate. When the first flexible substrate is bent and deformed, there is sufficient displacement margin between the multiple second flexible substrates, so that the flexible semiconductor refrigeration sheet can be bent without damaging the internal circuit connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 The present invention is a flow chart of the preparation method proposed.

[0027] Figure 2 This is a schematic structural diagram of the second flexible substrate of the present invention being completely disconnected.

[0028] Figure 3 for Figure 2 A magnified view of the structure at point A.

[0029] Figure 4 This is a schematic structural diagram of the first flexible substrate of the present invention being a whole polyimide film.

[0030] Figure 5 This is a structural schematic diagram of the first flexible substrate of the present invention being cut into multiple first sub-substrates.

[0031] Figure 6 It is a structural schematic diagram of a partial connection between the second flexible substrates of the present invention.

[0032] Figure 7 This is a schematic diagram of the concentric circle structure formed by the second flexible substrate of the present invention.

[0033] Figure 8This is a schematic diagram of the second flexible substrate of the present invention forming a U-shaped structure.

[0034] Description of reference numerals:

[0035] A first flexible substrate 1 ; a second flexible substrate 2 ; a semiconductor die 3 ; and a heat transfer plate 4 . DETAILED DESCRIPTION

[0036] The following will be combined with the Figure 1 To the attached Figure 5 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0037] It should be noted that if there are any directions involved in the embodiments of the present invention, they shall be based on the directions shown in the drawings, such as front and back. Figure 1 The specific Figure 1 The left side is the front, Figure 1 The right side is the back; at the same time Figure 2 As shown in the figure, the left-right direction is roughly the horizontal direction, and the up-down direction shown in the figure is the vertical direction. If a specific posture changes, the directional indication will also change accordingly.

[0038] See also Figures 1 to 8 The present application provides a method for preparing a flexible semiconductor refrigeration sheet, wherein the first flexible substrate 1 and the second flexible substrate 2 are films made of polyimide material.

[0039] Polyimide, also known as PI, boasts excellent flexibility, heat resistance, electrical insulation, lightweight, and biocompatibility, making it widely used in electronics and electrical engineering. Polyimide film is yellow and transparent, with a relative density of 1.39 to 1.45. It exhibits outstanding resistance to high temperatures, radiation, chemical corrosion, and electrical insulation, and can withstand long-term use in air at temperatures of 250 to 280°C. Its tensile strength is 200 MPa at 20°C and exceeds 100 MPa at 200°C. It is used as a substrate for flexible printed circuit boards and as an insulation material for various high-temperature-resistant motors and electrical appliances.

[0040] The specific steps are as follows:

[0041] Solder paste printing: First, two polyimide films are selected as the first flexible substrate 1 and the second flexible substrate 2, and the first solder paste is printed on one side of the first flexible substrate 1, and the second solder paste is printed on one side of the second flexible substrate 2.

[0042] First patch: The semiconductor crystal grains 3 are then mounted on the first solder paste on the first flexible substrate 1 in the form of solid crystals or SMT patches. It should be noted that there are multiple semiconductor crystal grains 3, and these semiconductor crystal grains 3 are arranged in a matrix. The semiconductor crystal grains 3 are made of N-type semiconductor and P-type semiconductor materials, and the surface area and volume of each semiconductor crystal grain 3 are consistent to ensure that each semiconductor crystal grain 3 has the same cooling or heating effect after being energized, so that the flexible semiconductor refrigeration sheet prepared in this application has a uniform cooling and heating effect. The semiconductor material includes one or more of bismuth telluride, silicon, germanium, silicon-germanium alloy, and silicon carbide. In other embodiments, it can also be other types of semiconductor materials. The semiconductor crystal grains 3 are divided into N-type crystals and P-type crystals according to the different materials they are made of, and the N-type crystals and P-type crystals are arranged in an alternating manner, and the ratio of the number of N-type crystals to P-type crystals is 1:1. In other embodiments, manual placement or other types of placement methods may be used, as long as the semiconductor die 3 can be placed on the first flexible substrate 1 printed with the first solder paste, and the cold ends of the semiconductor die 3 are all arranged to face the same side, and the hot ends are facing opposite to the cold ends.

[0043] First reflow soldering: The first flexible substrate 1 and the semiconductor die 3 after the first patching are then subjected to a first reflow soldering for curing.

[0044] Second patch: After the first reflow, take out the first flexible substrate 1, so that the semiconductor die 3 on the first flexible substrate 1 faces the side of the second flexible substrate 2 printed with the second solder paste. Then, attach the second flexible substrate 2 to the semiconductor die 3, so that the side of the semiconductor die 3 facing away from the first flexible substrate 1 is attached to the second solder paste.

[0045] Second reflow soldering: After the second patching is completed, the first flexible substrate 1 and the second flexible substrate 2 are subjected to a second reflow soldering and curing process.

[0046] It's important to note that the melting point of the first solder paste is greater than the melting point of the second solder paste, the temperature of the first reflow process is higher than the melting point of the first solder paste, and the temperature of the second reflow process is higher than the melting point of the second solder paste but lower than the melting point of the first solder paste. This allows the semiconductor die 3 to solidify on the first flexible substrate 1 after the first reflow process, preventing the semiconductor die 3 from shifting during the second bonding process, which could lead to misalignment, cracks, or breakage. The second reflow process solidifies the semiconductor die 3 and multiple second flexible substrates 2. Furthermore, the second reflow process, with a temperature lower than the melting point of the first solder paste, prevents the already solidified first solder paste from melting, ensuring that the semiconductor die 3 is securely fixed to the first flexible substrate 1. This effectively secures the semiconductor die 3 to the first and second flexible substrates 1 and 2, preventing shifting and improving product yield.

[0047] Substrate Cutting: The second flexible substrate 2 is cut to obtain multiple smaller second sub-substrates. Importantly, these second sub-substrates are cut into either completely disconnected or partially connected states. While this embodiment utilizes laser cutting, other cutting methods capable of precisely cutting polyimide films may also be employed in other embodiments.

[0048] Welding wires: Wires for connecting to an external power source are welded on the first flexible substrate 1 and / or the second flexible substrate 2. The arrangement of the wires enables electricity to flow through the flexible semiconductor refrigeration sheet prepared in the present application.

[0049] Glue dispensing: After the wire bonding is completed, glue is sprayed between the first flexible substrate 1 and the second flexible substrate 2 to protect the internal structure and semiconductor grains, and has waterproof and anti-oxidation functions.

[0050] Here, in the preparation of the flexible semiconductor cooling sheet proposed in this application, the glue dispensing process is arranged to be carried out after the wire bonding process. The logic behind this arrangement is that if the glue used in the glue dispensing process is applied in advance, it may have an adverse effect on the subsequent wire bonding process, such as interfering with the welding quality or causing unnecessary pollution. Therefore, in order to ensure the accuracy and reliability of the wire bonding, the glue dispensing step is placed at the end, thereby ensuring the functional integrity of the semiconductor cooling sheet while also taking into account the efficiency and orderliness of the production process.

[0051] Optionally, in order to improve the thermal conductivity of the flexible semiconductor refrigeration sheet prepared in the present application, a heat transfer plate may be installed on the first flexible substrate 1 and the second flexible substrate 2 .

[0052] Specifically, before solder paste printing is performed on the first and second flexible substrates 1 and 2, multiple heat transfer plates 4 are attached to the side of the first flexible substrate 1 not printed with the first solder paste, and multiple heat transfer plates 4 are attached to the side of the second flexible substrate 2 not printed with the second solder paste. In this embodiment, the heat transfer plates 4 are coated with glue and attached to the first and second flexible substrates 1 and 2 by lamination. In other embodiments, the heat transfer plates 4 may be attached in other ways, as long as they can be secured to the first and second flexible substrates 1 and 2.

[0053] The heat transfer plate 4 is made of a thermally conductive metal, ceramic material, or a ceramic material coated with a thermally conductive metal. In this embodiment, the heat transfer plate 4 is a stainless steel sheet. Thermally conductive metals include one or more of silver, copper, aluminum, silver-copper alloys, silver-aluminum alloys, copper-aluminum alloys, and silver-copper-aluminum alloys. Ceramic materials include one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide. In other embodiments, the thermally conductive metal may also be a thermally conductive metal such as iron or nickel, or its alloys.

[0054] The present application will be further described below with reference to specific embodiments:

[0055] Example 1

[0056] See also Figures 2 to 4 In this embodiment, the first flexible substrate 1 is a whole polyimide film, and the second flexible substrate 2 is a polyimide film that has been cut into multiple, completely disconnected sheets of smaller polyimide film, with a gap between two adjacent second sub-substrates. This design allows the first flexible substrate 1 to bend and adjust according to the contour of the required installation surface, thereby better fitting the installation surface of non-planar structures such as curved surfaces. Since the multiple second sub-substrates of the second flexible substrate 2 are in a completely disconnected and independent state, the gaps between the second sub-substrates provide sufficient displacement margin when the first flexible substrate 1 is bent and deformed. As a result, the flexible semiconductor refrigeration sheet can be effectively prevented from breaking due to stress concentration during the bending process, allowing the flexible semiconductor refrigeration sheet to bend without damaging the internal circuit connections, thereby ensuring that the flexible semiconductor refrigeration sheet can still operate normally after bending. The flexible semiconductor refrigeration sheet prepared in this application can be fitted to installation surfaces of various complex shapes, thereby enhancing the adaptability and application range of the flexible semiconductor refrigeration sheet.

[0057] Example 2

[0058] See also Figure 4 and Figure 6 In this embodiment, the first flexible substrate 1 is a whole polyimide film, and the multiple second flexible substrates 2 are multiple polyimide films with smaller areas that have been cut and partially connected. The two adjacent second sub-substrates are partially connected together. When the first flexible substrate 1 is bent according to the shape of the bonding surface, these second sub-substrates can not only provide the necessary displacement margin between each other to adapt to the bending deformation, but also form a certain mutual restraint force between the partially connected second sub-substrates. Since the adjacent second sub-substrates are partially connected, the restraint force between them helps to maintain the structural stability and integrity of the entire flexible semiconductor refrigeration sheet in the bent state, and prevents the cooling effect and the reliability of the circuit connection from being affected by excessive local deformation. This design enables the flexible semiconductor refrigeration sheet prepared in this application to more specifically adapt to the local extreme deformation conditions that may be encountered in actual applications.

[0059] Example 3

[0060] See also Figure 5 and Figure 6In this embodiment, the first flexible substrate 1 is cut into multiple first sub-substrate segments, with adjacent segments at least partially connected. The second flexible substrate 2 is composed of multiple, partially connected, smaller polyimide films. Compared to Example 1, the multi-segment design of the first flexible substrate 1 allows for greater bending deformation of the flexible semiconductor cooling sheet. Furthermore, the connections between the multiple first sub-substrate segments ensure that the flexible semiconductor cooling sheet maintains electrical connectivity during bending.

[0061] Example 4

[0062] See Figure 2 、 Figure 3 and Figure 5 In this embodiment, the first flexible substrate 1 is cut into multiple first sub-substrate segments, with adjacent segments at least partially connected. The multiple second flexible substrates 2 are cut into multiple, completely separate, smaller polyimide films. Compared to Example 3, the multiple second sub-substrates are completely separate, independent pieces. This design allows for greater bending deformation of the flexible semiconductor cooling sheet. Furthermore, the connections between the multiple first sub-substrates of the first flexible substrate 1 ensure that the flexible semiconductor cooling sheet maintains electrical connectivity during bending.

[0063] Example 5

[0064] In this embodiment, the second sub-substrate is cut into annular and circular shapes, and multiple second sub-substrates are arranged in an inner-outer nested manner to form a Figure 7 The concentric circle structure shown. It is understandable that the shape of the first flexible substrate 1 can also be adaptively modified according to the shape of the second flexible substrate 2, as long as the internal circuit of the flexible semiconductor refrigeration sheet can remain connected when it is bent. In practical applications, when the flexible semiconductor refrigeration sheet needs to be installed on a spherical surface, this concentric circle structure can make the flexible semiconductor refrigeration sheet fit more closely to the spherical surface. It is understandable that the shapes of the first flexible substrate 1 and the second flexible substrate 2 after being cut are highly flexible and customizable. According to the specific shape and requirements of the working surface to be bonded, the multiple second sub-substrates can also be flexibly set as follows Figure 8 The U-shaped structure shown, or any other shape suitable for a specific application scenario, further improves versatility.

[0065] Based on the disclosure and teachings of the above description, those skilled in the art may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and modifications and variations of the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although certain specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for preparing a flexible semiconductor refrigeration sheet, characterized in that: The following steps are involved: Solder paste printing: printing a first solder paste on one side of a first flexible substrate (1), and printing a second solder paste on one side of a second flexible substrate (2); First patching: attaching one side of a semiconductor crystal grain (3) to a first solder paste on a first flexible substrate (1), wherein a plurality of semiconductor crystal grains (3) are provided and arranged in a matrix; First reflow soldering: performing first reflow soldering and curing on the semiconductor crystal grain (3) and the first flexible substrate (1) after the first patching; Second patching: attaching the second flexible substrate (2) to the semiconductor crystal grains (3) of the first flexible substrate (1) that has completed the first reflow soldering, so that the other side of the semiconductor crystal grains (3) arranged in a matrix is attached to the second solder paste of the second flexible substrate (2); Second reflow soldering: performing a second reflow soldering to solidify the first flexible substrate (1) and the second flexible substrate (2) after the mounting is completed; Cutting the substrate: cutting the second flexible substrate (2) so that the second flexible substrate (2) is cut into a plurality of completely disconnected or partially connected second sub-substrates.

2. The method for preparing a flexible semiconductor refrigeration sheet according to claim 1, characterized in that: In the step of cutting the substrate, the first flexible substrate (1) is cut into multiple sections of first sub-substrates, and two adjacent sections of the first sub-substrates are at least partially connected together.

3. The method for preparing a flexible semiconductor refrigeration sheet according to claim 1, characterized in that: The semiconductor crystal grains (3) are made of semiconductor materials, which are N-type and P-type semiconductor materials, including one or more of bismuth telluride, silicon, germanium, silicon-germanium alloy, and silicon carbide.

4. The method for preparing a flexible semiconductor refrigeration sheet according to claim 3, characterized in that: The semiconductor crystal grains (3) include N-type crystal grains and P-type crystal grains. In the first patch step, the mounting method adopted is solid crystal or SMT patch form. The N-type crystal grains and the P-type crystal grains are arranged in an alternating arrangement, and the number of the N-type crystal grains and the number of the P-type crystal grains are the same.

5. The method for preparing a flexible semiconductor refrigeration sheet according to claim 1, characterized in that: The following steps are also included: Welding wires: welding wires for connecting to an external power source on the first flexible substrate (1) and / or the second flexible substrate (2); Glue dispensing: spraying glue between the first flexible substrate (1) and the second flexible substrate (2) after wire bonding is completed.

6. The method for preparing a flexible semiconductor refrigeration sheet according to claim 1, characterized in that: The first flexible substrate (1) and the second flexible substrate (2) are thin films made of polyimide material.

7. The method for preparing a flexible semiconductor refrigeration sheet according to claim 1, characterized in that: Before the solder paste printing step, a plurality of heat transfer plates are mounted on the side of the first flexible substrate (1) on which the first solder paste is not printed, and a plurality of heat transfer plates are mounted on the side of the second flexible substrate (2) on which the second solder paste is not printed.

8. The method for preparing a flexible semiconductor refrigeration sheet according to claim 7, characterized in that: The second sub-substrate is cut into a ring shape or a circle shape, and a plurality of the second sub-substrates form a concentric circle structure.

9. The method for preparing a flexible semiconductor refrigeration sheet according to claim 8, characterized in that: A heat transfer plate (4) having the same shape as the second sub-base plate is mounted on each of the second sub-base plates.

10. The method for preparing a flexible semiconductor refrigeration sheet according to claim 7, characterized in that: The heat transfer plate (4) is a heat-conducting metal, a ceramic material, or a ceramic material with a heat-conducting metal plated on the surface. The heat-conducting metal includes one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, and silver-copper-aluminum alloy. The ceramic material includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

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