A method for preparing a semiconductor refrigeration sheet and a module

Abstract

The present application belongs to the technical field of semiconductor refrigeration sheets, and provides a method for preparing a semiconductor refrigeration sheet and a module, wherein in the method for preparing the semiconductor refrigeration sheet, a first solder paste is printed on a first substrate, and a second solder paste is printed on a second substrate, and the melting point of the second solder paste is lower than that of the first solder paste. The first substrate and the crystal grain are firstly subjected to the first patch and the first reflow, and then the first substrate with the crystal grain is subjected to the second patch, and then the second reflow is performed. The crystal grain is first solidified on the first substrate through the first reflow, and the temperature of the second reflow is higher than the melting temperature of the second solder paste and lower than the melting temperature of the first solder paste, so as to avoid the position shift of the crystal grain during the patch process, and the phenomenon of uneven arrangement, tilt, cracks, and damage of the crystal grains occurs. The first solder paste is not melted during the second reflow, so as to ensure that the crystal grains are neatly arranged and fixed on the first substrate.

Description

Technical Field

[0001] The present application belongs to the technical field of semiconductor refrigeration sheets, and specifically relates to a method for preparing a semiconductor refrigeration sheet and a module. Background Art

[0002] Semiconductor electronic refrigeration is a high-tech that has developed rapidly internationally in recent years. Semiconductor refrigerators are a new type of refrigerator that achieves refrigeration through the Peltier effect. The Peltier effect is that when a direct current is passed through a thermocouple composed of two semiconductor materials of different polarities, heat transfer will occur between the hot and cold ends. By using this principle and the thermoelectric properties of semiconductor materials, a refrigerator with a temperature range of -50 to 80°C, a large or small working volume, refrigeration, cooling, constant temperature and other functions, and point-by-point temperature control can be made. With the development of society, people's requirements for environmental comfort have become higher and higher. Traditional heat transfer methods such as fans, cold pumps, and heating cannot fully meet people's heat dissipation or heating needs in various fields. Semiconductor refrigerators are accepted by everyone because of their small size, no mechanical transmission parts, no noise, fast cold and hot conversion, high reliability, long life, no environmental pollution, flexible design, miniaturization, and reciprocity of cooling and heating.

[0003] The preparation of semiconductor refrigeration chip modules includes two processes: refrigeration chip production and module production. The refrigeration chip production process includes processes such as grain cutting, gold plating, solder paste printing, grain patching, and reflow soldering. At present, the grain patching process mostly uses a fixture for manual alignment and patching, or uses a solid crystal method for patching. The manual chip patching method using a fixture has insufficient precision, the position deviation of the pasted grain is relatively large, and it is not neat, and uneven force may also cause grain damage. And in the preparation process of the cooling plate, since the upper and lower sides of the crystal are connected to the upper and lower DBC ceramic substrates respectively through solder paste, the solder paste on the upper and lower sides must go through the reflow process. In the currently commonly used production method, solder paste printing and patching are first completed on a ceramic substrate, and then it is aligned with another ceramic substrate that has been printed with solder paste through a fixture, and then reflow is performed together. In this way, before reflow, since the solder paste on both sides of the crystal is in soft contact, slight vibrations and uneven force during the operation of the fixture will cause uneven arrangement, tilting, and cracks in the crystal, affecting the electrical and life performance of the cooling plate.

[0004] During the preparation of the module, the main method in the industry currently uses thermal grease as a connector between the cooling plate and the copper plate, and between the cooling plate and the copper plate. On the one hand, the thermal conductivity of thermal grease is far inferior to that of solder paste, and the heat generated rapidly by the module cannot be conducted in time, thus greatly affecting the heat transfer performance of the module. On the other hand, the stability of the fixation with thermal grease is not good enough. Summary of the invention

[0005] In response to the problems of the prior art, the present application provides a method for preparing a semiconductor refrigeration sheet and a module, which effectively avoids the problems of uneven arrangement, tilt, cracks, and breakage of semiconductor refrigeration sheet grains.

[0006] The technical solutions adopted by this application to solve the above technical problems are as follows:

[0007] On the one hand, the present application provides a method for preparing a semiconductor refrigeration sheet, comprising the following steps:

[0008] Solder paste printing: printing a first solder paste on the surface of the first substrate; printing a second solder paste on the surface of the second substrate; the melting point of the second solder paste is lower than the melting point of the first solder paste;

[0009] First patch: one side of the semiconductor die is mounted on the first solder paste of the first substrate;

[0010] First reflow soldering: The semiconductor die and the first substrate that have been completed by the first patch are subjected to the first reflow soldering and solidified;

[0011] Second patch: the first substrate that has undergone the first reflow soldering is placed in correspondence with the second substrate, so that the other side of the semiconductor die is mounted on the second solder paste of the second substrate;

[0012] Second reflow: The first substrate and the second substrate after mounting are subjected to a second reflow curing process, wherein the temperature of the second reflow is higher than the melting point of the second solder paste, and the temperature of the second reflow is lower than the melting point of the first solder paste.

[0013] Preferably, the melting point of the first solder paste is 230-260°C, and the melting point of the second solder paste is 200-230°C.

[0014] Preferably, the printing temperature of the first solder paste is 230-260°C, and the printing temperature of the second solder paste is 200-230°C.

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

[0016] Wafer cutting: Cutting semiconductor materials into semiconductor wafers;

[0017] Wafer gold plating: depositing a metal coating on at least part of the surface of the cut semiconductor wafer;

[0018] Die cutting: Semiconductor wafers with metal coating on the surface are cut into semiconductor grains.

[0019] Preferably, the semiconductor material is an N-type or P-type semiconductor material, including one or more of bismuth telluride, silicon, germanium, silicon-germanium alloy, and silicon carbide.

[0020] Preferably, in the grain cutting step, the semiconductor grains include N-type grains and P-type grains; in the first mounting step, the mounting method is solid crystal or SMT mounting form, and the mounting order is an alternating arrangement order of N-type, P-type, N-type, and P-type. In the mounting step, the ratio of the number of N-type grains: P-type grains is 1:1.

[0021] Preferably, in the step of gold plating the wafer, the metal in the metal plating layer includes one or more of copper, nickel, gold, copper-nickel alloy, copper-gold alloy, nickel-gold alloy, and copper-nickel-gold alloy.

[0022] Preferably, in the wafer gold plating step, a metal coating is deposited on both sides of the cut semiconductor wafer.

[0023] Preferably, the metal plating layer has a thickness of 5 to 100 μm.

[0024] Preferably, the semiconductor wafer has a thickness of 0.5 to 5 mm, and the semiconductor grain size is 0.5 to 5.0 mm.

[0025] Preferably, the first substrate includes one or more of a DBC ceramic substrate, a DPC ceramic substrate, and a multilayer ceramic substrate, and the ceramic substrate material of the first substrate includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide; the second substrate includes one or more of a DBC ceramic substrate, a DPC ceramic substrate, and a multilayer ceramic substrate, and the ceramic substrate material of the second substrate includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

[0026] Preferably, the method further comprises the following steps:

[0027] Wire bonding: wires for introducing an external power source are bonded on the first substrate and / or the second substrate.

[0028] On the other hand, the present application provides a method for preparing a semiconductor refrigeration chip module, comprising the following steps: preparing a semiconductor refrigeration chip by the method for preparing a semiconductor refrigeration chip described above;

[0029] Solder paste printing: printing a third solder paste on the thermal conductive sheet; printing a fourth solder paste on the thermal conductive substrate, wherein the melting point of the third solder paste is lower than the melting point of the second solder paste, and the melting point of the fourth solder paste is lower than the melting point of the third solder paste;

[0030] Third patch: mount one side of the semiconductor cooling sheet to the third solder paste of the thermal conductive sheet;

[0031] Third reflow soldering: performing a third reflow soldering solidification on the semiconductor cooling sheet and the heat conducting sheet printed with the third solder paste, wherein the temperature of the third reflow soldering is higher than the melting point of the third solder paste, and the temperature of the third reflow soldering is lower than the melting point of the second solder paste;

[0032] Fourth patch: mount the other side of the semiconductor cooling sheet with the heat conductive sheet that has been cured by the third reflow soldering to the fourth solder paste of the heat conductive substrate;

[0033] Fourth reflow: The thermally conductive substrate after the fourth patch is completed and printed with the fourth solder paste is subjected to a fourth reflow curing, wherein the temperature of the fourth reflow is higher than the melting point of the fourth solder paste, and the temperature of the fourth reflow is lower than the melting point of the third solder paste.

[0034] Preferably, the melting point of the third solder paste is 170-200°C; the melting point of the fourth solder paste is 136-170°C.

[0035] Preferably, the printing temperature of the third solder paste is 170-200°C, and the printing temperature of the fourth solder paste is 136-170°C.

[0036] Preferably, the thickness of the thermally conductive sheet is 1.0 to 5.0 mm, and the thickness of the thermally conductive substrate is 3 to 30 mm.

[0037] Preferably, the heat conductive sheet comprises one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, silver-copper-aluminum alloy, and ceramic materials with heat conductive metal plated on the surface, and the ceramic materials comprise one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide;

[0038] The thermally conductive substrate includes one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, silver-copper-aluminum alloy, and ceramic materials with thermally conductive metal plated on the surface; the ceramic materials include one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

[0039] Beneficial effects of this application:

[0040] The present application provides a method for preparing a semiconductor refrigeration sheet, wherein a first solder paste is printed on a first substrate, and a second solder paste is printed on a second substrate, and the melting point of the first solder paste is higher than the melting point of the second solder paste. The first substrate and semiconductor crystal grains are firstly subjected to the first patch and the first reflow soldering, and the semiconductor crystal grains are firstly solidified on the first substrate through the first reflow soldering, so as to avoid the crystal grain position shifting during the patch process, and the semiconductor crystal grains are arranged unevenly, tilted, cracked, damaged, etc. Then, the first substrate with semiconductor crystal grains is subjected to the second patch and the second reflow soldering solidification, and the temperature of the second reflow soldering is greater than the melting point of the second solder paste and less than the melting point of the first solder paste. This requirement can ensure that the temperature of the second reflow soldering is lower than the melting point of the first solder paste, and the first solder paste is not melted during the second reflow soldering process, thereby ensuring that the semiconductor crystal grains are neatly arranged and fixed on the first substrate, and effectively avoiding the semiconductor crystal grain position shifting, unevenness or uneven force during the movement of the first substrate, which causes the semiconductor crystal grains to crack and damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of a single placement process;

[0042] Figure 2 It is a schematic diagram of the secondary mounting process;

[0043] Figure 3 It is a side view of the semiconductor refrigeration plate structure;

[0044] Figure 4 It is a three-dimensional diagram of the structure of the semiconductor refrigeration piece;

[0045] Figure 5 It is a top view of the semiconductor refrigeration plate module structure 1;

[0046] Figure 6 It is a front view of the semiconductor refrigeration plate module structure 1;

[0047] Figure 7 It is a front view of the semiconductor refrigeration plate module structure 2;

[0048] Description of reference numerals:

[0049] 1. First substrate; 21. First solder paste; 22. Second solder paste; 23. Third solder paste; 24. Fourth solder paste; 3. N-type crystal grains; 4. P-type crystal grains; 5. Second substrate; 6. Wires; 7. Thermal conductive sheet; 8. Semiconductor cooling sheet; 9. Thermal conductive substrate. DETAILED DESCRIPTION

[0050] In order to make the technical problems, technical solutions and beneficial effects solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0051] See also Figure 1 to Figure 4 As shown, the present application provides a method for preparing a semiconductor refrigeration sheet, comprising the following steps:

[0052] Solder paste printing: printing a first solder paste 21 on the surface of the first substrate 1; printing a second solder paste 22 on the surface of the second substrate 5; the melting point of the second solder paste 22 is lower than the melting point of the first solder paste 21;

[0053] First chip mounting: mounting one side of the semiconductor die to the first solder paste 21 of the first substrate 1;

[0054] First reflow soldering: the semiconductor crystal grains and the first substrate 1 that have been completed by the first patch are subjected to first reflow soldering and solidified;

[0055] Second patch: the first substrate 1 and the second substrate 5 that have undergone the first reflow soldering are placed in correspondence with each other, so that the other side of the semiconductor crystal grain is mounted on the second solder paste 22 of the second substrate 5;

[0056] Second reflow: The first substrate 1 and the second substrate 5 after mounting are subjected to a second reflow curing process, wherein the temperature of the second reflow is higher than the melting point of the second solder paste 22 , and the temperature of the second reflow is lower than the melting point of the first solder paste 21 .

[0057] The first substrate 1 is used to print the first solder paste 21, and the second substrate 5 is used to print the second solder paste 22, and the melting point of the first solder paste 21 is higher than that of the second solder paste 22. The first substrate 1 and the semiconductor crystal grain are firstly mounted and reflowed for the first time, and then the first substrate 1 with the semiconductor crystal grain is mounted for the second time with the second substrate 5. Compared with the traditional method of first mounting the semiconductor crystal grain, the first substrate 1, and the second substrate 5 by using a solid crystal method, an SMT mounting method, or a manual mounting method using a fixture, and then performing a reflow, the present application first solidifies the semiconductor crystal grain on the first substrate 1 through the first reflow, thereby avoiding the position shift of the semiconductor crystal grain during the mounting process, and the occurrence of uneven arrangement, tilt, cracks, and damage of the semiconductor crystal grains. The first substrate 1 and the second substrate 5 that have completed the first reflow soldering are subjected to a second patch and a second reflow soldering curing, and the temperature of the second reflow soldering is higher than the melting point of the second solder paste 22, and the temperature of the second reflow soldering is lower than the melting point of the first solder paste 21. This requirement can ensure that the temperature of the second reflow soldering is lower than the melting point of the first solder paste 21, and the first solder paste 21 is not melted during the second reflow soldering, thereby ensuring that the semiconductor grains are neatly arranged and fixed on the first substrate 1, and effectively avoiding the position deviation of the grains during the movement of the grains and the first substrate 1, and the occurrence of cracks and breakage of the grains due to unevenness or uneven force.

[0058] In some embodiments, the melting point of the first solder paste 21 is 230-260° C., and the melting point of the second solder paste 22 is 200-230° C.

[0059] By using two solder pastes with different melting points, namely the first solder paste 21 and the second solder paste 22, different reflow soldering curing temperatures can be effectively selected in the two reflow soldering operations, which can not only effectively fix the semiconductor grains to the first substrate 1 and the second substrate 5 respectively, but also avoid melting the already cured solder paste, reduce rework, and improve production efficiency.

[0060] The printing temperature of the first solder paste 21 is 230-260° C., and the printing temperature of the second solder paste 22 is 200-230° C. In some embodiments, if the solder paste printing temperature is lower than this temperature range, the solder paste is not melted, which is not conducive to the implementation of the solder paste printing process. If the solder paste is higher than this temperature range, the solder paste is completely melted into liquid, and the liquid solder paste covers the remaining non-solder paste specified positions, which brings inconvenience to production and is not conducive to the welding of the substrate wire position. At the same time, the temperature is too high, which affects the thermal conductivity and cooling performance of the semiconductor grains.

[0061] In some embodiments, the method for preparing a semiconductor refrigeration sheet provided in the present application further includes the following steps:

[0062] Wafer cutting: Cutting semiconductor materials into semiconductor wafers;

[0063] Wafer gold plating: depositing a metal coating on at least part of the surface of the cut semiconductor wafer;

[0064] Die cutting: Semiconductor wafers with metal coating on the surface are cut into semiconductor grains.

[0065] In some embodiments, the cutting method in wafer cutting and grain cutting can adopt the existing mechanical cutting method. The grain cutting step requires cutting into semiconductor grains of consistent specifications. The surface area and volume of each semiconductor grain are the same, ensuring that each semiconductor grain has the same cooling or heating effect after being powered on, and the prepared semiconductor cooling sheet 8 has more uniform cooling or heating. A metal coating is deposited on the surface of the semiconductor wafer to increase the thermal conductivity of the semiconductor cooling sheet 8.

[0066] The semiconductor material is an N-type and P-type semiconductor material, including one or more of bismuth telluride, silicon, germanium, silicon carbide, and silicon-germanium alloy. In some embodiments, the N-type / P-type semiconductor material of the present application can be bismuth telluride, silicon, silicon-germanium alloy, or other types of semiconductor materials.

[0067] In the step of cutting the grains, the semiconductor wafer with the metal coating on the surface is cut to form semiconductor grains, and the semiconductor grains are N-type grains 3 and P-type grains 4. In the first step of mounting, the mounting method is die bonding or SMT mounting, and the arrangement order of the semiconductor grains is N-type, P-type, N-type, P-type alternating arrangement order, wherein the number ratio of N-type grains 3:P-type grains 4 is 1:1.

[0068] In some embodiments, the mounting method may be die bonding, SMT, or even manual mounting, or other types of mounting methods, as long as the semiconductor crystal grains are mounted on the first substrate 1 printed with the first solder paste 21. The arrangement order of the semiconductor crystal grains may be an alternating arrangement order of N-type, P-type, N-type, and P-type, or an alternating arrangement order of P-type, N-type, P-type, and N-type, and the arrangement order of N-type and P-type crystal grains may be specified according to actual design requirements.

[0069] In the step of gold plating the wafer, the metal in the metal plating layer includes one or more of copper, nickel, gold, copper-nickel alloy, copper-gold alloy, nickel-gold alloy, and copper-nickel-gold alloy.

[0070] In the wafer gold plating step, a metal coating is deposited on both sides of the cut semiconductor wafer.

[0071] In some embodiments, the metal type in the metal plating layer of the present application can be copper, nickel, gold and alloys thereof, and can also be other heat-conducting metals, such as aluminum and other heat-conducting metals. The present application provides that the metal plating layer is deposited on both sides of the semiconductor wafer, and according to actual needs, it can be selected to plate the metal plating layer on only one side, or on a part of it.

[0072] The thickness of the metal coating is 5 to 100 μm.

[0073] In some embodiments, metal coatings are deposited on both sides of N-type grains and P-type grains, wherein the thickness of the metal coatings ranges from 5 to 100 μm. Within this range, the thickness of the metal coatings can better exert the thermal conductivity of the metal, that is, after the semiconductor refrigeration piece is powered on, the semiconductor grains generate heat or cool, and the metal coatings deposited on the surface of the semiconductor grains transfer it away, which is more conducive to the performance of the semiconductor refrigeration piece.

[0074] The thickness of the semiconductor wafer is 0.5 to 5 mm, the size of the semiconductor grain is 0.5 to 5.0 mm, and the shape of the semiconductor grain is polygonal.

[0075] In some embodiments, the semiconductor wafer provided in this embodiment has a thickness of 0.5 to 5 mm, and the semiconductor grain size specification is 0.5 to 5 mm. The size of the wafer and the grain is limited, which is convenient for wafer cutting to form semiconductor grains with consistent specifications during the generation process, which is conducive to quality supervision; the grains require consistent size specifications, which is not only conducive to the arrangement of semiconductor grains in the patch process, but also the semiconductor grains are of the same size during the operation of the semiconductor refrigeration sheet 8, and the cold and heat conversion is fast, and the heat or cooling effect generated is the same, which meets people's needs. At the same time, the shape of the semiconductor grains in this embodiment is polygonal, for example, it can be a rectangle, square, hexagon, octagon, etc.

[0076] The first substrate 1 includes one or more of a DBC ceramic substrate, a DPC ceramic substrate, and a multilayer ceramic substrate, and the ceramic substrate material of the first substrate 1 includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide; the second substrate 5 includes one or more of a DBC ceramic substrate, a DPC ceramic substrate, and a multilayer ceramic substrate, and the ceramic substrate material of the second substrate 5 includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

[0077] In some embodiments, the present application includes but is not limited to the types of the first substrate 1 and the second substrate 5 . The first substrate 1 and the second substrate 5 may also be made of materials such as silicon carbide.

[0078] In some embodiments, the method for preparing the semiconductor refrigeration sheet further includes the following steps: Wire welding: welding a wire 6 on the first substrate 1 and / or the second substrate 5 .

[0079] See also Figure 5-6 As shown, the present application provides a method for preparing a semiconductor refrigeration module, comprising the following steps:

[0080] A semiconductor refrigeration sheet 8 prepared by the above-mentioned method for preparing a semiconductor refrigeration sheet;

[0081] Solder paste printing: printing a third solder paste 23 on the heat conducting sheet 7; printing a fourth solder paste 24 on the heat conducting substrate 9, the melting point of the third solder paste 23 is lower than the melting point of the second solder paste 22, and the melting point of the fourth solder paste 24 is lower than the melting point of the third solder paste 23;

[0082] Third patch: one side of the semiconductor cooling sheet 8 is mounted on the third solder paste 23 of the thermal conductive sheet 7;

[0083] Third reflow soldering: The semiconductor cooling sheet 8 and the heat conducting sheet 7 printed with the third solder paste 23 are reflow soldered and solidified for the third time, and the temperature of the third reflow soldering is higher than the melting point of the third solder paste 23, and the temperature of the third reflow soldering is lower than the melting point of the second solder paste 22;

[0084] Fourth patch: the other side of the semiconductor cooling sheet 8 with the heat conducting sheet 7 which has been cured by the third reflow soldering is mounted on the fourth solder paste 24 of the heat conducting substrate 9;

[0085] Fourth reflow: The thermal conductive substrate 9 after the fourth patch is completed and printed with the fourth solder paste 24 is subjected to the fourth reflow curing. The temperature of the fourth reflow is higher than the melting point of the fourth solder paste 24 , and the temperature of the fourth reflow is lower than the melting point of the third solder paste 23 .

[0086] In some embodiments, the temperature of the third reflow soldering is higher than the melting point of the third solder paste 23, and the temperature of the third reflow soldering is lower than the melting point of the second solder paste 22, so as to avoid the first solder paste 21 and the second solder paste 22 being melted during the third reflow soldering, and the semiconductor grains solidified with the first substrate 1 and the second substrate 5 being tilted, arranged irregularly, or even the semiconductor grains being separated from the first substrate 1 or the second substrate 5. The temperature of the fourth reflow soldering is higher than the melting point of the fourth solder paste 24, and the temperature of the fourth reflow soldering is lower than the melting point of the third solder paste 23, so as to avoid the third solder paste 23 being melted during the fourth reflow soldering, and the semiconductor cooling sheet 8 solidified with the thermal conductive sheet 7 being arranged irregularly, tilted, and the like.

[0087] In some embodiments, in the fourth patch step, the number of semiconductor cooling plates 8 with heat conducting plates 7 is greater than two.

[0088] The preparation method of the semiconductor refrigeration chip module provided by the present application adopts solder paste as a connecting agent, which greatly improves the thermal conductivity. At the same time, the solder paste reflow soldering is a rigid connection, and the stability of the prepared semiconductor refrigeration chip module is good. The semiconductor refrigeration chip module prepared by the present application has the advantages of small size, no noise, fast cold and heat conversion, high reliability, long life, flexible design, miniaturization, etc., and the same product can meet the needs of cooling and heating at the same time, which is more convenient to use, replacing traditional heat transfer methods such as fans and cold pumps, and has fast cooling or heating speed to meet people's needs.

[0089] The present application uses solder pastes with different melting points when preparing semiconductor cooling sheets and modules, and the corresponding reflow soldering temperature is strictly controlled. The temperature of each reflow soldering is lower than the solder paste temperature before the reflow soldering process, thereby avoiding the deviation and tilting of semiconductor grains and improving production efficiency.

[0090] Preferably, the melting point of the third solder paste 23 is 170-200°C; the melting point of the fourth solder paste 24 is 136-170°C.

[0091] In some embodiments, in this embodiment, the melting point of the third solder paste 23 is lower than the melting point of the second solder paste 22, and the melting point of the fourth solder paste 24 is lower than the melting point of the third solder paste 23, which is beneficial to the control of the reflow temperature during the third and fourth reflow soldering, thereby improving production efficiency.

[0092] In the preparation method of the semiconductor cooling chip module, the printing temperature of the third solder paste 23 is 170-200° C., and the printing temperature of the fourth solder paste 24 is 136-170° C. In some embodiments, if the solder paste printing temperature is lower than this temperature range, the solder paste is not melted, which is not conducive to the implementation of the solder paste printing process. If the solder paste is higher than this temperature range, the solder paste is completely melted into liquid, and the liquid flows and the solder paste covers the remaining non-specified positions of the solder paste, which brings inconvenience to production and is not conducive to the welding of the substrate wire position. At the same time, the temperature is too high, which affects the thermal conductivity and cooling performance of the semiconductor grains.

[0093] The thickness of the heat conducting sheet 7 is 1.0 to 5.0 mm, and the thickness of the heat conducting substrate 9 is 3 to 30 mm.

[0094] In some embodiments, the thickness of the thermal conductive sheet 7 is 1.0 to 5.0 mm, and the thickness of the thermal conductive substrate 9 is 3 to 30 mm. The thickness of the thermal conductive sheet 7 and the thermal conductive substrate 9 can match the thickness of the prepared semiconductor refrigeration sheet 8, the thickness of the first substrate 1, and the thickness of the second substrate 5, so that the refrigeration or thermal conductivity performance of the prepared semiconductor refrigeration sheet module is better exerted.

[0095] The thermal conductive sheet 7 includes one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, silver-copper-aluminum alloy, and ceramic materials with thermally conductive metals plated on the surface, and the ceramic materials include one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide; the thermal conductive substrate 9 includes one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, silver-copper-aluminum alloy, and ceramic materials with thermally conductive metals plated on the surface, and the ceramic materials include one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

[0096] In some embodiments, the present application does not limit the types of the thermally conductive sheet 7 and the thermally conductive substrate 9. The thermally conductive sheet 7 and the thermally conductive substrate 9 may also include thermally conductive metals such as iron and nickel and their alloys, or other types of ceramic materials.

[0097] In some embodiments, there are multiple semiconductor cooling sheets 8 and multiple thermal conductive sheets 7, and multiple thermal conductive sheets 7 are attached to one side surface of multiple semiconductor cooling sheets 8 in a one-to-one correspondence, and the other side surfaces of multiple semiconductor cooling sheets 8 are attached to the same thermal conductive substrate 9.

[0098] Specifically, Figure 6 As shown, in one embodiment, a plurality of the semiconductor cooling sheets 8 are linearly spaced and arranged.

[0099] like Figure 7 As shown, in another embodiment, a plurality of the semiconductor cooling sheets 8 are arranged in a matrix.

[0100] The present invention is further described below in conjunction with specific embodiments.

[0101] The following are only some examples of embodiments and comparative examples provided in this application. The inventor may add embodiments and comparative examples according to actual conditions, or modify the operating procedures and parameters in the embodiments or comparative examples, all of which are protected within the scope of protection of the present invention.

[0102] Example 1

[0103] Wafer cutting: N-type and P-type bismuth telluride crystal rods are cut into P-type and N-type semiconductor wafers respectively, with a cutting thickness of 0.5 mm.

[0104] Wafer gold plating: deposit a metal copper coating on both sides of the cut P-type and N-type semiconductor wafers.

[0105] Grain cutting: P-type and N-type semiconductor wafers with a metal copper coating on the surface are cut into P-type and N-type semiconductor grains with a size of 0.5 mm, where the grain shape is square.

[0106] Solder paste printing: The first solder paste 21 is printed on the DBC ceramic first substrate 1, and the printing solder paste temperature is 236°C; the second solder paste 22 is printed on the surface of the boron nitride ceramic second substrate 5. The printing solder paste temperature is 206°C; the melting point of the second solder paste 22 is 205°C, and the melting point of the first solder paste 21 is 235°C.

[0107] The first bonding: one side of the cut N-type and P-type semiconductor grains is bonded to the first solder paste 21 on the DBC ceramic first substrate 1 by using a die bonding bonding method, wherein the arrangement of the grains is based on the design of the current on the DBC ceramic first substrate 1 to ensure that the current flows in an alternating arrangement of N-type, P-type, N-type, P-type, etc.; the ratio of the number of N-type and P-type grains is maintained at a 1:1 relationship.

[0108] First reflow soldering: The semiconductor grains and the DBC ceramic first substrate 1 that have been completed by the first patch are subjected to the first reflow soldering and solidified, so that the solder paste on the DBC ceramic first substrate 1 is solidified and formed, wherein the curing temperature of the first reflow soldering is 240°C.

[0109] Second patch: The DBC ceramic first substrate 1 and the boron nitride ceramic second substrate 5 that have completed the first reflow soldering are placed in correspondence with each other, so that the other side of the N-type and P-type semiconductor grains are mounted to the second solder paste 22 of the boron nitride ceramic second substrate 5. After the mounting is completed, the upper side is the DBC ceramic first substrate 1, the lower side is the boron nitride ceramic second substrate 5, and the middle is the N-type and P-type semiconductor grains, and an electrode contact position is left on one of the DBC ceramic first substrates 1.

[0110] Second reflow soldering: The DBC ceramic first substrate 1 and the boron nitride ceramic second substrate 5 after mounting are subjected to a second reflow soldering and curing, and the temperature of the second reflow soldering is 210°C.

[0111] Wire welding: Weld the wire 6 pins at the position where the electrode contacts are left on the DBC ceramic first substrate 1. At this point, a cooling plate is completed, the ceramic substrate connected to the positive electrode is the hot side, and the ceramic substrate connected to the negative electrode is the cold side.

[0112] Solder paste printing: the third solder paste 23 is printed on the copper thermal conductive sheet 7, and the printing solder paste temperature is 176°C; the fourth solder paste 24 is printed on the copper thermal conductive substrate 9, and the printing solder paste temperature is 141°C; the melting point of the third solder paste 23 is 175°C, and the melting point of the fourth solder paste 24 is 140°C.

[0113] Third patch: mount the cold surface of the semiconductor cooling sheet 8 to the third solder paste 23 of the copper heat conducting sheet 7;

[0114] Third reflow soldering: The semiconductor cooling sheet 8 and the copper heat conducting sheet 7 printed with the third solder paste 23 are subjected to a third reflow soldering curing. The temperature of the third reflow soldering is 180°C.

[0115] Fourth patch: the hot surface of the semiconductor cooling sheet 8 with the copper heat conductive sheet 7 which has been cured by the third reflow soldering is mounted on the fourth solder paste 24 of the copper heat conductive substrate 9, and the number of semiconductor cooling sheets 8 with the copper heat conductive sheet 7 is 20;

[0116] Fourth reflow soldering: The copper thermal conductive substrate 9 on which the fourth patch is completed and printed with the fourth solder paste 24 is subjected to fourth reflow soldering and curing. The temperature of the fourth reflow soldering is 150°C.

[0117] Example 2

[0118] Wafer cutting: N-type and P-type silicon crystal rods are cut into P-type and N-type semiconductor wafers respectively, with a cutting thickness of 3mm.

[0119] Wafer gold plating: deposit a metal copper coating on both sides of the cut P-type and N-type semiconductor wafers.

[0120] Die cutting: P-type and N-type semiconductor wafers with a metal copper coating on the surface are cut into rectangular semiconductor dice with a length of 2.5 mm and a width of 2.0 mm.

[0121] Solder paste printing: Print the first solder paste 21 on the DPC ceramic first substrate 1 at a solder paste printing temperature of 242°C; print the second solder paste 22 on the surface of the alumina ceramic second substrate 5 at a solder paste printing temperature of 213°C; the melting point of the second solder paste 22 is 210°C, and the melting point of the first solder paste 21 is 240°C.

[0122] The first bonding: one side of the cut N-type and P-type semiconductor grains is bonded to the first solder paste 21 on the DPC ceramic first substrate 1 by using a die bonding bonding method, wherein the arrangement of the grains is based on the design of the current on the DPC ceramic first substrate 1 to ensure that the current flows in an alternating arrangement of N-type, P-type, N-type, P-type, etc.; the number of N-type and P-type grains maintains a 1:1 relationship.

[0123] First reflow soldering: The semiconductor grains and the DPC ceramic first substrate 1 that have been completed by the first patch are subjected to the first reflow soldering and solidified, so that the solder paste on the DPC ceramic first substrate 1 is solidified and formed, wherein the curing temperature of the first reflow soldering is 245°C.

[0124] Second patch: The DPC ceramic first substrate 1 and the alumina ceramic second substrate 5 that have completed the first reflow soldering are placed in correspondence with each other, so that the other side of the N-type and P-type semiconductor grains are mounted to the second solder paste 22 of the alumina ceramic second substrate 5. After the mounting is completed, the upper side is the DPC ceramic first substrate 1, the lower side is the alumina ceramic second substrate 5, and the middle is the N-type and P-type semiconductor grains, and an electrode contact position is left on one of the DPC ceramic first substrates 5.

[0125] Second reflow soldering: The DPC ceramic first substrate 1 and the alumina ceramic second substrate 5 after mounting are subjected to a second reflow soldering curing, and the temperature of the second reflow soldering is 220°C.

[0126] Welding wire: Weld the lead wire 6 pins at the position where the electrode contacts are left on the alumina ceramic second substrate 5. At this point, a cooling plate is completed, and the ceramic substrate connected to the positive electrode is the hot side, and the ceramic substrate connected to the negative electrode is the cold side.

[0127] Solder paste printing: the third solder paste 23 is printed on the silver thermal conductive sheet 7 at a printing solder paste temperature of 193°C; the fourth solder paste 24 is printed on the aluminum thermal conductive substrate 9 at a printing solder paste temperature of 160°C. The melting point of the third solder paste 23 is 190°C, and the melting point of the fourth solder paste 24 is 150°C.

[0128] Third patch: mount the cold surface of the semiconductor cooling sheet 8 to the third solder paste 23 of the silver thermal conductive sheet 7;

[0129] Third reflow soldering: The semiconductor cooling sheet 8 and the silver heat conductive sheet 7 printed with the third solder paste 23 are subjected to a third reflow soldering and solidification. The temperature of the third reflow soldering is 195°C.

[0130] Fourth patch: the hot surface of the semiconductor cooling sheet 8 with the silver heat conductive sheet 7 which has been cured by the third reflow soldering is mounted on the fourth solder paste 24 of the aluminum heat conductive substrate 9, and the number of the semiconductor cooling sheets 8 with the silver heat conductive sheet 7 is 30;

[0131] Fourth reflow soldering: The aluminum thermal conductive substrate 9 on which the fourth patch is completed and printed with the fourth solder paste 24 is subjected to fourth reflow soldering and curing. The temperature of the fourth reflow soldering is 160°C.

[0132] Example 3

[0133] Wafer cutting: N-type and P-type silicon-germanium alloy crystal rods are cut into P-type and N-type semiconductor wafers respectively, with a cutting thickness of 5mm.

[0134] Wafer gold plating: deposit a metal copper coating on both sides of the cut P-type and N-type semiconductor wafers.

[0135] Grain cutting: P-type and N-type semiconductor wafers with a metal copper coating on the surface are cut into P-type and N-type semiconductor grains with a size of 4 mm, where the grain shape is hexagonal.

[0136] Solder paste printing: a first solder paste 21 is printed on the first aluminum nitride ceramic substrate 1 at a solder paste printing temperature of 258°C; a second solder paste 22 is printed on the surface of the second aluminum nitride ceramic substrate 5 at a solder paste printing temperature of 226°C; the melting point of the second solder paste 22 is 224°C, and the melting point of the first solder paste 21 is 256°C.

[0137] The first patch: one side of the cut N-type and P-type semiconductor grains is mounted on the first solder paste 21 on the first aluminum nitride ceramic substrate 1 by SMT patch method, wherein the arrangement of the grains is based on the design of the current on the first aluminum nitride ceramic substrate 1 to ensure that the current flow direction is: N-type, P-type, N-type, P-type, etc., in an alternating arrangement; the number of N-type and P-type grains maintains a 1:1 relationship.

[0138] First reflow soldering: The semiconductor grains and the first aluminum nitride ceramic substrate 1 that have been completed by the first patch are subjected to the first reflow soldering curing to cure the solder paste on the first aluminum nitride ceramic substrate 1, wherein the curing temperature of the first reflow soldering is 260°C.

[0139] Second patch: The aluminum nitride ceramic first substrate 1 and the aluminum nitride ceramic second substrate 5 that have completed the first reflow soldering are placed in correspondence with each other, so that the other side of the N-type and P-type semiconductor grains are mounted to the second solder paste 22 of the aluminum nitride ceramic second substrate 5. After the mounting is completed, the upper and lower sides are ceramic substrates, and the middle is the N-type and P-type semiconductor grains. An electrode contact position is left on one of the aluminum nitride ceramic first substrates 1.

[0140] Second reflow soldering: The aluminum nitride ceramic first substrate 1 and the aluminum nitride ceramic second substrate 5 after mounting are subjected to a second reflow soldering and solidification, and the temperature of the second reflow soldering is 230°C.

[0141] Wire welding: Weld the lead wire 6 pins at the position where the electrode contacts are left on the aluminum nitride ceramic first substrate 1. At this point, a cooling plate is completed, the ceramic substrate connected to the positive electrode is the hot side, and the ceramic substrate connected to the negative electrode is the cold side.

[0142] Solder paste printing: print the third solder paste 23 on the aluminum nitride ceramic substrate thermal conductive sheet 7, and the printing solder paste temperature is 198°C; print the fourth solder paste 24 on the aluminum nitride ceramic substrate thermal conductive substrate 9, and the printing solder paste temperature is 168°C. The melting point of the third solder paste 23 is 195°C, and the melting point of the fourth solder paste 24 is 167°C.

[0143] Third patching: the cold surface of the semiconductor cooling sheet 8 is mounted on the third solder paste 23 of the aluminum nitride ceramic substrate heat conducting sheet 7;

[0144] Third reflow soldering: The semiconductor cooling sheet 8 and the aluminum nitride ceramic substrate heat conducting sheet 7 printed with the third solder paste 23 are reflow soldered and solidified for the third time. The temperature of the third reflow soldering is 198°C.

[0145] Fourth patch: the hot surface of the semiconductor cooling sheet 8 with the aluminum nitride ceramic substrate heat conductive sheet 7 which has been cured by the third reflow soldering is mounted on the fourth solder paste 24 of the aluminum nitride ceramic substrate heat conductive substrate 9. The number of semiconductor cooling sheets 8 with the aluminum nitride ceramic substrate heat conductive sheet 7 is 15.

[0146] Fourth reflow soldering: The aluminum nitride ceramic substrate thermal conductive substrate 9 on which the fourth patch is completed and printed with the fourth solder paste 24 is subjected to fourth reflow soldering and curing. The temperature of the fourth reflow soldering is 168°C.

[0147] Comparative Example 1:

[0148] The preparation method of the semiconductor refrigeration sheet of Comparative Example 1 is different from that of Example 1 in that the melting points of the solder pastes printed four times are all the same, that is, the first solder paste has a melting point of 235°C, there is no first reflow soldering, and the second reflow soldering is directly carried out, and the curing temperature of the second reflow soldering and the curing temperature of the fourth reflow soldering are the same as the curing temperature of the third reflow soldering, which is 238°C.

[0149] Comparative Example 2:

[0150] The preparation methods of the semiconductor cooling sheets of Comparative Example 1 and Comparative Example 2 are the same. During the module preparation process, the connecting agent used in Comparative Example 1 is solder paste, and the connecting agent used in Comparative Example 2 is thermal conductive silicone grease, and the rest are the same.

[0151] The performance test of semiconductor refrigeration film and semiconductor refrigeration film module, the test data is as follows:

[0152] The resistance characteristic test method of the cooling plate is: the test is carried out using direct current with a frequency of 1KHZ. The resistance characteristics of cooling plates of different sizes and specifications are different.

[0153] The maximum temperature difference test method for the cooling plate is: fix the cold surface temperature, then increase the current to test the hot surface temperature, and test to get the maximum temperature difference.

[0154] Table 1 Performance test data of semiconductor refrigeration chips and modules are as follows

[0155]

[0156] The resistance of the semiconductor refrigeration sheet prepared in Example 1-3 is lower than that in Comparative Example 1, and the maximum temperature difference of the semiconductor refrigeration sheet prepared in Example 1-3 is higher than that in Comparative Example 1, mainly because the semiconductor refrigeration sheet in Example 1-3 adopts two reflow soldering, and the temperature of the second reflow soldering is lower than that of the first solder paste, the grains are arranged neatly, and there is no tilting phenomenon. After the prepared semiconductor refrigeration sheet is powered on, the refrigeration or thermal conductivity of the grains that are neatly arranged and free of cracks and damage is better exerted. The cooling capacity of the semiconductor refrigeration sheet module prepared in Example 1-3 is greater than the cooling capacity data of the module in Comparative Example 1. This is because the temperature of the third reflow soldering adopted in Example 1-3 is lower than the melting point of the first and second solder pastes, and the temperature of the fourth reflow soldering is lower than the melting points of the third, second, and first solder pastes. In the preparation process of the module, the stable solidification between the grains, the first substrate, the second substrate, and the thermal conductive sheet is guaranteed, and the phenomenon of grain tilting and uneven arrangement is avoided, thereby improving the cooling performance of the module. Compared with Example 2, Examples 1-3 use thermal conductive silicone grease as the connecting agent in Example 2, which has a lower thermal conductivity than solder paste and greatly reduces the thermal conductivity. The cooling capacity of the prepared semiconductor refrigeration module is low.

[0157] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a semiconductor refrigeration module, characterized in that: The steps include: Preparation of semiconductor refrigeration chips; Solder paste printing: printing a third solder paste on the thermal conductive sheet; printing a fourth solder paste on the thermal conductive substrate, wherein the melting point of the third solder paste is lower than the melting point of the second solder paste, and the melting point of the fourth solder paste is lower than the melting point of the third solder paste; Third patch: mount one side of the semiconductor cooling sheet to the third solder paste of the thermal conductive sheet; Third reflow soldering: performing a third reflow soldering solidification on the semiconductor cooling sheet and the heat conducting sheet printed with the third solder paste, wherein the temperature of the third reflow soldering is higher than the melting point of the third solder paste, and the temperature of the third reflow soldering is lower than the melting point of the second solder paste; Fourth patch: mount the other side of the semiconductor cooling sheet with the heat conductive sheet that has been cured by the third reflow soldering to the fourth solder paste of the heat conductive substrate; Fourth reflow soldering: the thermally conductive substrate on which the fourth patch is completed and printed with the fourth solder paste is subjected to fourth reflow soldering and curing, wherein the temperature of the fourth reflow soldering is higher than the melting point of the fourth solder paste, and the temperature of the fourth reflow soldering is lower than the melting point of the third solder paste; The method for preparing the semiconductor refrigeration sheet comprises the following steps: Solder paste printing: printing a first solder paste on the surface of the first substrate; printing a second solder paste on the surface of the second substrate; the melting point of the second solder paste is lower than the melting point of the first solder paste; First patch: one side of the semiconductor die is mounted on the first solder paste of the first substrate; First reflow soldering: The semiconductor die and the first substrate that have been completed by the first patch are subjected to the first reflow soldering and solidified; Second patch: the first substrate that has undergone the first reflow soldering is placed in correspondence with the second substrate, so that the other side of the semiconductor die is mounted on the second solder paste of the second substrate; Second reflow: The first substrate and the second substrate after mounting are subjected to a second reflow curing process, wherein the temperature of the second reflow is higher than the melting point of the second solder paste, and the temperature of the second reflow is lower than the melting point of the first solder paste.

2. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The melting point of the first solder paste is 230-260° C., and the melting point of the second solder paste is 200-230° C.

3. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The printing temperature of the first solder paste is 230-260° C.; the printing temperature of the second solder paste is 200-230° C.

4. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The method for preparing the semiconductor refrigeration sheet also includes the following steps: Wafer cutting: Cutting semiconductor materials into semiconductor wafers; Wafer gold plating: depositing a metal coating on at least part of the surface of the cut semiconductor wafer; Die cutting: Semiconductor wafers with metal coating on the surface are cut into semiconductor grains.

5. The method for preparing a semiconductor refrigeration module according to claim 4, characterized in that: The semiconductor material is an N-type or P-type semiconductor material, including one or more of bismuth telluride, silicon, germanium, silicon-germanium alloy, and silicon carbide.

6. The method for preparing a semiconductor refrigeration module according to claim 4 or 5, characterized in that: In the grain cutting step, the semiconductor grains include N-type grains and P-type grains; in the first patch step, the mounting method is solid crystal or SMT patch form, and the mounting order is an alternating arrangement order of N-type, P-type, N-type, and P-type. In the patch step, the ratio of the number of N-type grains: P-type grains is 1:

1.

7. The method for preparing a semiconductor refrigeration module according to claim 4, characterized in that: In the step of gold plating the wafer, the metal in the metal plating layer includes one or more of copper, nickel, gold, copper-nickel alloy, copper-gold alloy, nickel-gold alloy, and copper-nickel-gold alloy.

8. The method for preparing a semiconductor refrigeration module according to claim 4, characterized in that: In the wafer gold plating step, metal plating layers are deposited on both sides of the cut semiconductor wafer.

9. The method for preparing a semiconductor refrigeration module according to claim 4, characterized in that: The thickness of the metal coating is 5-100 μm.

10. The method for preparing a semiconductor refrigeration module according to claim 4, characterized in that: The thickness of the semiconductor wafer is 0.5-5 mm, and the particle size of the semiconductor grain is 0.5-5.0 mm.

11. The method for preparing a semiconductor refrigeration module according to claim 1 or 4, characterized in that: The first substrate includes one or more of a DBC ceramic substrate, a DPC ceramic substrate, and a multilayer ceramic substrate, and the ceramic substrate material of the first substrate includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide; the second substrate includes one or more of a DBC ceramic substrate, a DPC ceramic substrate, and a multilayer ceramic substrate, and the ceramic substrate material of the second substrate includes one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

12. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The method for preparing the semiconductor refrigeration sheet also includes the following steps: Wire bonding: wires for introducing an external power source are bonded on the first substrate and / or the second substrate.

13. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The melting point of the third solder paste is 170-200° C.; the melting point of the fourth solder paste is 136-170° C.

14. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The printing temperature of the third solder paste is 170-200°C, and the printing temperature of the fourth solder paste is 136-170°C.

15. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The thickness of the thermal conductive sheet is 1.0-5.0 mm, and the thickness of the thermal conductive substrate is 3-30 mm.

16. The method for preparing a semiconductor refrigeration module according to claim 1, characterized in that: The heat conducting sheet comprises one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, silver-copper-aluminum alloy, and ceramic materials with heat-conducting metal plated on the surface, and the ceramic materials comprise one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide; The thermally conductive substrate includes one or more of silver, copper, aluminum, silver-copper alloy, silver-aluminum alloy, copper-aluminum alloy, silver-copper-aluminum alloy, and ceramic materials with thermally conductive metal plated on the surface; the ceramic materials include one or more of aluminum nitride, boron nitride, aluminum oxide, and beryllium oxide.

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