Brazing filler metal, brazing filler metal preparation method and IGBT radiator manufacturing method

Abstract

The invention provides brazing filler metal, a brazing filler metal preparation method and an IGBT radiator manufacturing method. Wherein the mass percent of Sn in the brazing filler metal is smaller than 0.1%. The brazing filler metal is prepared from the following components in parts by mass: 90.3 to 96.8 parts of Zn and 2.5 to 3.2 parts of Ag. The brazing filler metal further comprises a metal auxiliary component, and the metal auxiliary component comprises 0.4-0.5 part of Cu; or 0.4 to 0.5 part of Cu and 5.2 to 5.5 parts of Al. According to the brazing filler metal, the content of Sn is reduced, Zn serves as a base material to be matched with Ag, so that the welding temperature of the brazing filler metal is adjusted to range from 300 DEG C to 500 DEG C, after the brazing filler metal is applied to welding of an IGBT radiator, the packaging process of an IGBT is not likely to be affected, and in the welding process of the brazing filler metal, the performance of the IGBT radiator is not likely to become poor. By adding the metal auxiliary components, the welding strength and the oxidation resistance of the brazing filler metal after welding can be adjusted.

Description

Technical Field

[0001] The present application relates to the field of welding technology, and in particular to a solder, a solder preparation method, and an IGBT heat sink manufacturing method. Background Art

[0002] With the rapid development of the new energy vehicle industry and the maturity of technology, it is urgent to solve the problem of fast and precise manufacturing; controlling the stable operation of IGBT, the core component of the vehicle system, has become a technology that the entire new energy vehicle pays more attention to. With the improvement of automobile performance, the working power of IGBT, one of its core components, will be greatly improved, and the heat generation will increase sharply. At present, the device for cooling IGBT generally adopts a cooling solution in which an IGBT heat sink with heat dissipation fins and a fan are combined for heat dissipation. Its advantages are simple structure, easy implementation, and convenient on-site construction and installation. However, the existing heat dissipation substrate or heat dissipation fin generally adopts cold forging stamping or hot forging stamping process. Due to the large number of forging production processes, 23 processes, and a long production cycle, the most difficult to control is the high degree of dependence on the forging process. The forging process is difficult to control. The forging process requires high blank quality. The blank quality directly determines the quality and efficiency of many subsequent process products. Low fur quality leads to more waste, which increases the cost of waste recycling, which is extremely unfavorable to green ecological manufacturing. Summary of the invention

[0003] The present application provides a solder, a solder preparation method and an IGBT heat sink manufacturing method, which are convenient for welding and fixing the heat dissipation fins and the heat dissipation substrate of the IGBT heat sink.

[0004] The first aspect of the embodiment of the present application provides a solder. The mass percentage of Sn in the solder is less than 0.1%. In terms of mass fractions, the solder includes: 90.3-96.8 parts of Zn, 2.5-3.2 parts of Ag. The solder also includes a metal auxiliary component, which is: 0.4-0.5 parts of Cu; or, 0.4-0.5 parts of Cu, 5.2-5.5 parts of Al; or, 2.1-5.8 parts of Al, 0.7-0.9 parts of Ni.

[0005] After the heat dissipation substrate and heat dissipation extension of the IGBT heat sink are welded, packaging welding is still required. If the melting point of the solder at the packaging welding coincides with the melting point of the solder at the heat dissipation substrate and the heat dissipation extension, the welding at the heat dissipation substrate and the heat dissipation extension will fail during packaging welding. Therefore, the melting point of the solder used at the heat dissipation substrate and the heat dissipation extension should be controlled above 300°C. If the melting point of the solder is too high, it is easy to cause the copper material performance of the IGBT heat sink to change when the solder melts, and the IGBT heat sink becomes soft as a whole and is difficult to meet the application scenarios of the IGBT heat sink. The solder provided in this application reduces the content of Sn, and uses Zn as the base material to match Ag, so as to adjust the solder welding temperature to between 300 and 500°C. After being applied to the welding of the IGBT heat sink, it is not easy to affect the packaging process of the IGBT, and it is not easy to cause the performance of the IGBT heat sink itself to deteriorate during the solder welding process. By adding metal auxiliary components, the welding strength after solder welding and the antioxidant ability can be adjusted. After reducing the Sn content, by adjusting the ratio of Zn, Ag and metal auxiliary components, this solder can generate a thicker and denser compound layer when used for welding copper IGBT heat sinks, thereby improving the connection strength and thermal conductivity. The heat dissipation extension can be a copper column or a copper heat dissipation fin.

[0006] Based on the first aspect, in an embodiment of the present application, the mass percentage of In in the solder is less than 0.1%.

[0007] This kind of solder reduces the In content, reduces the amount of solder oxidation during welding, increases the connection strength after the solder solidifies, and also increases the solder penetration rate of the weld.

[0008] Based on the first aspect, in the embodiment of the present application: when the metal auxiliary component is Cu 0.4-0.5 parts, the mass ratio of Zn, Ag and Cu in the solder is (96.5-96.8): (2.8-3.0): (0.4-0.5). When the metal auxiliary component is Cu 0.4-0.5 parts and Al 5.2-5.5 parts, the mass ratio of Zn, Ag, Cu and Al in the solder is (91.2-91.7): (2.5-2.8): (0.4-0.5): (5.2-5.5). When the metal auxiliary components are 2.1 to 5.8 parts of Al and 0.7 to 0.9 parts of Ni, the mass ratio of Zn, Ag, Al and Ni in the solder is (93.7 to 94.0): (2.9 to 3.1): (2.1 to 2.3): (0.8 to 0.9), or the mass ratio of Zn, Ag, Al and Ni in the solder is (90.3 to 90.7): (3.1 to 3.2): (5.3 to 5.8): (0.7 to 0.9).

[0009] Based on the experimental results, when the mass ratio of Zn, Ag and Cu in the solder is (96.5-96.8): (2.8-3.0): (0.4-0.5), the actual melting point of the solder is between 317 and 319°C, which meets the requirement of controlling the soldering temperature between 300 and 500°C. When the mass ratio of Zn, Ag, Cu and Al in the solder is (91.2-91.7): (2.5-2.8): (0.4-0.5): (5.2-5.5), the actual melting point of the solder is between 325 and 330°C, which meets the requirement of controlling the soldering temperature between 300 and 500°C. When the mass ratio of Zn, Ag, Al and Ni in the solder is (93.7-94.0): (2.9-3.1): (2.1-2.3): (0.8-0.9), the actual melting point of the solder is between 380 and 413°C, which meets the requirement of controlling the soldering temperature of the solder between 300 and 500°C. When the mass ratio of Zn, Ag, Al and Ni in the solder is (90.3-90.7): (3.1-3.2): (5.3-5.8): (0.7-0.9), the actual melting point of the solder is between 438 and 460°C, which meets the requirement of controlling the soldering temperature of the solder between 300 and 500°C.

[0010] Based on the first aspect, in an embodiment of the present application: when the metal auxiliary component is 0.4-0.5 parts of Cu, the mass ratio of Zn, Ag and Cu in the solder is 96.6:2.9:0.5. When the metal auxiliary component is 0.4-0.5 parts of Cu and 5.2-5.5 parts of Al, the mass ratio of Zn, Ag, Cu and Al in the solder is 91.5:2.7:0.4:5.4. When the metal auxiliary component is 2.1-5.8 parts of Al and 0.7-0.9 parts of Ni, the mass ratio of Zn, Ag, Cu and Al in the solder is 93.9:3.1:2.1:0.9, or the mass ratio of Zn, Ag, Cu and Al in the solder is 90.5:3.2:5.4:0.9.

[0011] Based on the experimental results, when the mass ratio of Zn, Ag and Cu in the solder is 96.6:2.9:0.5, the actual melting point of the solder is 318±1℃, which meets the requirement of controlling the soldering temperature between 300 and 500℃. When the mass ratio of Zn, Ag, Cu and Al in the solder is 91.5:2.7:0.4:5.4, the actual melting point of the solder is 330±1℃, which meets the requirement of controlling the soldering temperature between 300 and 500℃. When the mass ratio of Zn, Ag, Al and Ni in the solder is 93.9:3.1:2.1:0.9, the actual melting point of the solder is 410±1℃, which meets the requirement of controlling the soldering temperature between 300 and 500℃. When the mass ratio of Zn, Ag, Al and Ni in the solder is 90.5:3.2:5.4:0.9, the actual melting point of the solder is 448±1°C, which meets the requirement of controlling the welding temperature of the solder between 300 and 500°C.

[0012] The second aspect of the present application provides a method for preparing a solder, which is used to prepare the solder in any embodiment of the first aspect. The method for preparing the solder comprises:

[0013] Mixing the master alloy and adding a covering agent, and placing the master alloy in a heating chamber at a first temperature for heating until the master alloy is completely melted to form a molten metal;

[0014] The temperature of the heating chamber is raised to a second temperature, and the molten metal in the heating chamber is kept warm for more than 100 minutes;

[0015] The temperature of the heating chamber is lowered to the third temperature, and the molten metal in the heating chamber is kept warm for more than 20 minutes;

[0016] Place the molten metal in a cooling environment of 15 to 40°C until the molten metal forms a solid material, and the temperature difference between the solid material and the cooling environment is less than 50°C;

[0017] Remove the covering agent from the solid material.

[0018] This method of preparing solder is to preheat to a temperature at which it is completely melted, thereby reducing the risk of premature reaction in local areas leading to uneven distribution of hypoeutectic, eutectic and hypereutectic in the final solder. After heating to a second temperature, it is then kept warm for a long time, so that the molten metal can be fully mixed at a higher temperature, and in the subsequent cooling process, each area undergoes a roughly uniform eutectic reaction, so that the composition of the entire solder is roughly uniform, which facilitates the formation of a roughly uniform welding structure at the welding position after the solder is used for welding, thereby improving the overall mechanical properties.

[0019] Based on the second aspect, in an embodiment of the present application: the covering agent includes at least one of lithium chloride and potassium chloride.

[0020] The covering agent can play a role of heat preservation to a certain extent, thereby improving the heat preservation effect of the solder.

[0021] Based on the second aspect, in an embodiment of the present application, the first temperature is between 580 and 620°C, the second temperature is between 630 and 670°C, the third temperature is between 580 and 620°C, and the second temperature is greater than the first temperature and the second temperature.

[0022] This method for preparing solder is to preheat to a temperature at which it is completely melted, thereby reducing the risk of premature reaction in local areas leading to uneven distribution of subeutectics, eutectics and hypereutectics in the final solder. After heating to the second temperature again, it is kept warm for a long time, so that the molten metal can be fully mixed at a higher temperature, and in the subsequent cooling process, each area undergoes a roughly uniform eutectic reaction, so that the composition of the entire solder is roughly uniform, which facilitates the formation of a roughly uniform welding structure at the welding position after the solder is used for welding, thereby improving the overall mechanical properties. The first temperature, the second temperature and the third temperature are defined based on the characteristic that the welding temperature of the solder in the first aspect is between 300 and 500°C, so that the intermediate alloy can be completely melted at the first temperature and can be as uniform as possible under the insulation condition of the second temperature.

[0023] Based on the second aspect, in an embodiment of the present application, in the step of cooling the temperature of the heating chamber to the third temperature and keeping the molten metal in the heating chamber warm for more than 20 minutes, the molten metal is stirred at least 5 times every 8 to 12 minutes using a stirring rod.

[0024] In the solder preparation method, during the heat preservation process at the third temperature, the composition of the molten metal is made more uniform, so that during the solidification process of the molten metal, the generated crystal structure is as uniform as possible.

[0025] The third aspect of the present application provides a method for manufacturing an IGBT heat sink. The IGBT heat sink manufacturing method uses the solder provided in the first aspect or the solder prepared by the solder preparation method provided in the second aspect to prepare the IGBT heat sink. The IGBT heat sink manufacturing method includes:

[0026] The heat dissipation substrate is clamped by a first clamp, and a first mounting surface of the heat dissipation substrate is exposed from the first clamp along a mounting direction;

[0027] The heat dissipation extension member is clamped by a second clamp, and a second mounting surface of the heat dissipation extension member is exposed from the second clamp along the mounting direction;

[0028] Align the first fixture and the second fixture so that the second installation surface is located inside the first installation surface in a projection plane perpendicular to the installation direction, and the second fixture and the first fixture are movably matched along the installation direction;

[0029] The solder is arranged on the first mounting surface, and the heat dissipation substrate is heated to 20 to 50° C. above the melting point of the solder, and / or the solder is arranged on the second mounting surface, and the heat dissipation extension is heated to 20 to 50° C. above the melting point of the solder;

[0030] Using an ultrasonic tool head to apply ultrasonic waves to the solder, so that the solder melts and wets the heat dissipation substrate and the heat dissipation extension;

[0031] Stop applying ultrasonic waves to the solder, and the melted solder solidifies to weld and fix the heat dissipation substrate and the heat dissipation extension;

[0032] The first clamp is detached from the heat dissipation substrate, and the second clamp is detached from the heat dissipation extension.

[0033] This IGBT heat sink manufacturing method can roughly align the relative positions of the heat sink substrate and the heat sink extension, and then melt the solder through ultrasonic welding, and wet the heat sink substrate and the heat sink extension, so that the heat sink substrate and the heat sink extension can be welded quickly and in batches. In addition, the ultrasonic welding method can improve the filling effect of the solder between the heat sink substrate and the heat sink extension, thereby improving the welding effect.

[0034] Based on the third aspect, in an embodiment of the present application, after the step of stopping applying ultrasonic waves to the solder, the method further includes:

[0035] A welding gap with a preset width is controlled between the heat dissipation substrate and the heat dissipation extension, and the molten solder is filled in the welding gap;

[0036] At least part of the melted solder is removed outside the weld gap.

[0037] In this IGBT heat sink manufacturing method, by limiting the welding gap with a preset width between the heat dissipation substrate and the heat dissipation extension, when the ultrasonic tool applies ultrasonic waves, the heat dissipation substrate and the heat dissipation extension can have a relative movement amplitude of the preset width, thereby facilitating the melting of the solder, accelerating the diffusion reaction speed of the solder in the heat dissipation extension and the heat dissipation substrate, and prompting the two to form a metallurgical bond quickly. In addition, the welding gap with a preset width can facilitate solder filling, increase the contact area between the solder and the heat dissipation substrate, and the contact area between the solder and the heat dissipation extension, thereby improving the fixing effect of the solidified solder on the heat dissipation substrate and the heat dissipation extension.

[0038] Based on the third aspect, in an embodiment of the present application, before the molten solder solidifies to weld and fix the heat dissipation substrate and the heat dissipation extension, the method further includes:

[0039] The heat dissipation substrate, the heat dissipation extension and the molten solder are placed in an inert gas environment, wherein the inert gas includes at least one of nitrogen, argon and helium.

[0040] In this IGBT heat sink manufacturing method, an inert gas environment is formed by using at least one of nitrogen, argon and helium. On the one hand, nitrogen, argon and helium basically do not participate in the reaction of the solder components. On the other hand, these gases are easy to store and transport and can be continuously supplied to the manufacturing of the IGBT heat sink for a long time.

[0041] Based on the third aspect, in an embodiment of the present application, in the step of exposing the first fixture on the first mounting surface of the heat dissipation substrate along the mounting direction: the first mounting surface extends out of the first fixture along the mounting direction by 2 to 5 mm; and / or,

[0042] In the step of exposing the second fixture from the second mounting surface of the heat dissipation extension piece along the mounting direction: the second mounting surface protrudes from the second fixture by 2 to 5 mm along the mounting direction.

[0043] In the manufacturing method of the IGBT heat sink, the first mounting surface and / or the second mounting surface are extended to facilitate the solder to be arranged on the first mounting surface and / or the second mounting surface. The extended size of the first mounting surface and / or the second mounting surface is 2 to 5 mm, which can, on the one hand, allow the heat dissipation substrate and / or the heat dissipation extension to have a large enough area to be clamped by the clamp to maintain stability, and on the other hand, allow the heat dissipation substrate and / or the heat dissipation extension to expose a large enough area to be wetted by the molten solder. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The metallographic diagram of the solder numbered A2 in one embodiment of the present application is shown.

[0045] Figure 2 The metallographic diagram of the solder numbered B2 in one embodiment of the present application is shown.

[0046] Figure 3 The metallographic diagram of the solder numbered C2 in one embodiment of the present application is shown.

[0047] Figure 4 The metallographic diagram of the solder numbered D2 in one embodiment of the present application is shown.

[0048] Figure 5 A cross-sectional view of a clamp assembly in one embodiment of the present application is shown.

[0049] Figure 6 A cross-sectional view of a first clamp in an embodiment of the present application is shown.

[0050] Figure 7 A cross-sectional view of a first fixture in an embodiment of the present application is shown, wherein the solder is placed on a heat dissipation substrate.

[0051] Figure 8A cross-sectional view of a first clamp in an embodiment of the present application is shown, wherein no mounting groove is provided on the surface of the heat dissipation substrate.

[0052] Fig. 9 A cross-sectional view of a second clamp in an embodiment of the present application is shown.

[0053] Fig.10 A cross-sectional view of a second fixture in an embodiment of the present application is shown, wherein the second fixture is acted upon by an ultrasonic tool head and a preheating element.

[0054] Fig.11 The interface microstructure of the welding structure on the heat dissipation substrate side provided by one embodiment of the present application is shown, wherein the solder is A2 solder.

[0055] Fig.12 An interface microstructure diagram of a welding structure on the heat dissipation substrate side provided in one embodiment of the present application is shown, wherein the solder is B2 solder.

[0056] Fig.13 An interface microstructure diagram of a welding structure on the heat dissipation substrate side provided in one embodiment of the present application is shown, wherein the solder is a C2 solder.

[0057] Fig.14 An interface microstructure diagram of a welding structure on the heat dissipation substrate side provided in one embodiment of the present application is shown, wherein the solder is D2 solder.

[0058] Main component symbols

[0059] Fixture assembly 001

[0060] Brazing material 002

[0061] First fixture 010

[0062] First card slot 011

[0063] First Assembly Department 015

[0064] Heat dissipation substrate 020

[0065] First mounting surface 021

[0066] First working slot 023

[0067] Installation slot 025

[0068] Second fixture 030

[0069] Second card slot 031

[0070] Second working slot 033

[0071] Second assembly department 035

[0072] Heat dissipation extension 040

[0073] Second mounting surface 041

[0074] Force surface 043

[0075] Work piece 050

[0076] The third assembly department 051

[0077] Assembly Parts 060

[0078] Ultrasonic tool head 070

[0079] Preheating part 080

[0080] Installation direction X

[0081] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0082] The following specific embodiments illustrate the implementation of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this application are limited to the implementation. On the contrary, the purpose of introducing the application in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present application. In order to provide a deep understanding of the present application, the following description will include many specific details. The present application can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0083] The present invention will be described in more detail below. In the present specification, "%" referring to the composition of the solder alloy means "mass %" unless otherwise specified.

[0084] Example 1

[0085] This embodiment provides a solder of type A and a preparation method thereof. The solder of type A includes, by weight, 90.3 to 96.8 parts of Zn, 2.5 to 3.2 parts of Ag, and 0.4 to 0.5 parts of Cu as a metal auxiliary component. In terms of weight percentage, the content of Sn in the solder of type A is less than 0.1%, and the content of In is less than 0.1%.

[0086] The type A solder is prepared by:

[0087] The master alloy is mixed and a covering agent is added, and the master alloy is placed in a heating chamber at a first temperature of 580° C. and heated until the master alloy is completely melted to form a molten metal, wherein the master alloy includes an AgCu alloy, a single substance of Zn and a single substance of Ag, and the covering agent is a mixture of lithium chloride and potassium chloride;

[0088] The temperature of the heating chamber is raised to a second temperature of 630° C., and the molten metal in the heating chamber is kept warm for 100 minutes;

[0089] The temperature of the heating chamber is cooled to a third temperature of 580° C., the molten metal in the heating chamber is kept warm for 20 minutes, the molten metal is stirred for 5 turns with a stirring rod at the 8th minute, and the molten metal is stirred for 5 turns with a stirring rod at the 16th minute;

[0090] The molten metal is placed in a cooling environment at room temperature until the molten metal forms a solid material, and the temperature difference between the solid material and the room temperature is less than 5°C, and the room temperature is 25°C;

[0091] Remove the covering agent from the solid material.

[0092] It can be understood that the cooling environment has little effect on the crystals of the final solid material, and its temperature can be 15 to 40°C, and the real-time atmospheric temperature can be taken. Under the condition of the presence of temperature control equipment, the room temperature is generally taken as 25°C. Moreover, in the process of cooling the solid material to near room temperature, according to the actual production line requirements, the temperature of the solid material can be cooled to room temperature as much as possible, but the cooling can also be ended in advance, such as cooling the solid material to 50°C above room temperature. When the room temperature is 25°C, the solid material is cooled to 75°C and the covering agent on the solid material can be removed by tools.

[0093] Specifically, according to the preparation method of solder of type A, three solders with different compositions, A1, A2 and A3, are prepared as shown in Table 1. Table 1 also shows the melting points of A1, A2 and A3 in an argon environment at one atmospheric pressure.

[0094] Table 1 Mass percentage of components in solder of type A

[0095]

[0096] Figure 1 The metallographic diagram of the solder numbered A2 is also shown. Figure 1 As shown, the crystal structure of the solder is a network structure grown on a Zn base, wherein the network structure is a ZnAgCu eutectic structure.

[0097] Example 2

[0098] This embodiment provides a solder of type B and a preparation method thereof. The solder of type B includes, by weight, 91.2 to 91.7 parts of Zn, 2.5 to 2.8 parts of Ag, 0.4 to 0.5 parts of Cu as a metal auxiliary component, and 5.2 to 5.5 parts of Al. In terms of weight percentage, the content of Sn in the solder of type B is less than 0.1%, and the content of In is less than 0.1%.

[0099] The type B solder is prepared by:

[0100] The master alloy is mixed and a covering agent is added, and the master alloy is placed in a heating chamber at a first temperature of 600° C. for heating until the master alloy is completely melted to form a molten metal, wherein the master alloy includes AgCu alloy, ZnAl alloy, Zn element and Ag element, and the covering agent is a mixture of lithium chloride and potassium chloride;

[0101] The temperature of the heating chamber is raised to a second temperature of 650° C., and the molten metal in the heating chamber is kept warm for 120 minutes;

[0102] The temperature of the heating chamber is cooled to a third temperature of 600° C., the molten metal in the heating chamber is kept warm for 30 minutes, the molten metal is stirred for 5 turns with a stirring rod at the 10th minute, the molten metal is stirred for 5 turns with a stirring rod at the 20th minute, and the molten metal is stirred for 5 turns with a stirring rod at the 29th minute;

[0103] Place the molten metal in a cooling environment at 25°C until the molten metal forms a solid material, and the temperature difference between the solid material and the cooling environment is less than 5°C;

[0104] Remove the covering agent from the solid material.

[0105] It can be understood that the cooling environment has little effect on the crystals of the final solid material, and its temperature can be 15 to 40°C, and the real-time atmospheric temperature can be taken. Under the condition of the presence of temperature control equipment, the room temperature is generally taken as 25°C. Moreover, in the process of cooling the solid material to near room temperature, according to the actual production line requirements, the temperature of the solid material can be cooled to room temperature as much as possible, but the cooling can also be ended in advance, such as cooling the solid material to 50°C above room temperature. When the room temperature is 25°C, the solid material is cooled to 75°C and the covering agent on the solid material can be removed by tools.

[0106] Specifically, according to the preparation method of solder of type B, three solders with different compositions, B1, B2 and B3, were prepared, as shown in Table 2. Table 2 also shows the melting points of B1, B2 and B3 in an argon environment at one atmospheric pressure.

[0107] Table 2 Mass percentage of components in solder of type B

[0108]

[0109] Figure 2 The metallographic diagram of the solder numbered B2 is also shown. Figure 2 As shown, the crystal structure of the solder is dark granular and light reticular structures grown on the Zn base, wherein the dark granular structure is the ZnCuAl eutectic structure and the light reticular structure is the ZnAgAl eutectic structure.

[0110] Example 3

[0111] This embodiment provides a solder of type C and a preparation method thereof. The solder of type C includes, by weight, 93.7-94.0 parts of Zn, 2.9-3.1 parts of Ag, 2.1-2.3 parts of metal auxiliary components Al, and 0.8-0.9 parts of Ni. In terms of mass percentage, the content of Sn in the solder of type C is less than 0.1%, and the content of In is less than 0.1%.

[0112] The type C brazing filler metal is prepared by:

[0113] The master alloy is mixed and a covering agent is added, and the master alloy is placed in a heating chamber at a first temperature of 620° C. and heated until the master alloy is completely melted to form a molten metal, wherein the master alloy includes a ZnAl alloy, a single substance of Zn, a single substance of Ag, and a single substance of Ni, and the covering agent is a mixture of lithium chloride and potassium chloride;

[0114] The temperature of the heating chamber is raised to a second temperature of 670° C., and the molten metal in the heating chamber is kept warm for 120 minutes;

[0115] The temperature of the heating chamber is cooled to a third temperature of 620° C., the molten metal in the heating chamber is kept warm for 30 minutes, the molten metal is stirred 5 times with a stirring rod at the 10th minute, the molten metal is stirred 5 times with a stirring rod at the 20th minute, and the molten metal is stirred 5 times with a stirring rod at the 29th minute;

[0116] Place the molten metal in a cooling environment at 25°C until the molten metal forms a solid material, and the temperature difference between the solid material and the cooling environment is less than 5°C;

[0117] Remove the covering agent from the solid material.

[0118] It can be understood that the cooling environment has little effect on the crystals of the final solid material, and its temperature can be 15 to 40°C, and the real-time atmospheric temperature can be taken. Under the condition of the presence of temperature control equipment, the room temperature is generally taken as 25°C. Moreover, in the process of cooling the solid material to near room temperature, according to the actual production line requirements, the temperature of the solid material can be cooled to room temperature as much as possible, but the cooling can also be ended in advance, such as cooling the solid material to 50°C above room temperature. When the room temperature is 25°C, the solid material is cooled to 75°C and the covering agent on the solid material can be removed by tools.

[0119] Specifically, according to the preparation method of solder of type C, three solders with different compositions, C1, C2 and C3, were prepared, as shown in Table 3. Table 3 also shows the melting points of C1, C2 and C3 in an argon environment at one atmospheric pressure.

[0120] Table 3 Mass percentage of components in solder of type C

[0121]

[0122] Figure 3 The metallographic diagram of the solder numbered C2 is also shown. Figure 3 As shown in FIG. 1 , the crystal structure of the solder is a small granular structure and a large block structure grown on a Zn base. The small granular structure and the large block structure are both ZnAgAlNi eutectic structures, but the Ag content in the large block structure is significantly higher than that in the small granular structure.

[0123] Example 4

[0124] This embodiment provides a solder of type D and a preparation method thereof. The solder of type D includes, by mass, 90.3-90.7 parts of Zn, 3.1-3.2 parts of Ag, 5.3-5.8 parts of metal auxiliary components Al, and 0.7-0.9 parts of Ni. In terms of mass percentage, the content of Sn in the solder of type D is less than 0.1%, and the content of In is less than 0.1%.

[0125] The type D brazing filler metal is prepared by:

[0126] The master alloy is mixed and a covering agent is added, and the master alloy is placed in a heating chamber at a first temperature of 620° C. and heated until the master alloy is completely melted to form a molten metal, wherein the master alloy includes a ZnAl alloy, a single substance of Zn, a single substance of Ag, and a single substance of Ni, and the covering agent is a mixture of lithium chloride and potassium chloride;

[0127] The temperature of the heating chamber is raised to a second temperature of 670° C., and the molten metal in the heating chamber is kept warm for 120 minutes;

[0128] The temperature of the heating chamber is cooled to a third temperature of 620° C., the molten metal in the heating chamber is kept warm for 30 minutes, the molten metal is stirred 5 times with a stirring rod at the 10th minute, the molten metal is stirred 5 times with a stirring rod at the 20th minute, and the molten metal is stirred 5 times with a stirring rod at the 29th minute;

[0129] Place the molten metal in a cooling environment at 25°C until the molten metal forms a solid material, and the temperature difference between the solid material and the cooling environment is less than 5°C;

[0130] Remove the covering agent from the solid material.

[0131] It can be understood that the cooling environment has little effect on the crystals of the final solid material, and its temperature can be 15 to 40°C, and the real-time atmospheric temperature can be taken. Under the condition of the presence of temperature control equipment, the room temperature is generally taken as 25°C. Moreover, in the process of cooling the solid material to near room temperature, according to the actual production line requirements, the temperature of the solid material can be cooled to room temperature as much as possible, but the cooling can also be ended in advance, such as cooling the solid material to 50°C above room temperature. When the room temperature is 25°C, the solid material is cooled to 75°C and the covering agent on the solid material can be removed by tools.

[0132] Specifically, according to the preparation method of solder of type D, three solders with different compositions, D1, D2 and D3, were prepared, as shown in Table 4. Table 4 also shows the melting points of D1, D2 and D3 in an argon environment at one atmospheric pressure.

[0133] Table 4 Mass percentage of components in solder of type D

[0134]

[0135] Figure 4 The metallographic diagram of the solder numbered D2 is also shown. Figure 4 As shown in FIG. 1 , the crystal structure of the solder is a small granular structure and a large block structure grown on a Zn base. The small granular structure and the large block structure are both ZnAgAlNi eutectic structures, but the Ag content in the large block structure is significantly higher than that in the small granular structure.

[0136] Table 5 shows the melting points of A2, B2, C2, D2 and comparative example E under an atmosphere of argon. Among them, comparative example E is 95Pb5Sn solder, which is a ROSH (Restriction of the use of certain hazardous substances in electrical and electronic equipment) exempt solder.

[0137] Table 5 Comparison of melting points of solders of types A2, B2, C2, D2 and comparative example E

[0138]

[0139] As shown in Table 5, the type A solder, type B solder, type C solder and type D solder provided in the present application can control the melting point between 300 and 500°C, which can meet the subsequent packaging process of the IGBT heat sink and maintain the performance of the IGBT heat sink itself.

[0140] It is understandable that the solder may contain a small amount of Sn, with the content of Sn being less than 0.1%. Sn can also lower the melting point of the solder and increase the wettability of the solder.

[0141] Example 5

[0142] This embodiment provides a method for manufacturing an IGBT (Insulate-Gate Bipolar Transistor) heat sink. The IGBT heat sink manufacturing method is implemented by using a fixture assembly 001 in conjunction with an ultrasonic tool head 070.

[0143] like Figure 5 As shown, the fixture assembly 001 includes a first fixture 010 , a second fixture 030 and a workpiece 050 .

[0144] like Figure 6 and Figure 7 As shown, the first fixture 010 includes a first slot 011. The first slot 011 is used to hold the heat dissipation substrate 020. The heat dissipation substrate 020 can be a solid heat dissipation plate made of copper, or can be other structures such as a vacuum chamber heat sink. The heat dissipation substrate 020 has a first mounting surface 021 along the mounting direction X. Along the mounting direction X, the depth of the first slot 011 is less than the thickness of the heat dissipation substrate 020, so that when the heat dissipation substrate 020 is inserted into the first slot 011, the first mounting surface 021 can extend out of the first slot 011. The first mounting surface 021 extends out of the first slot 011, which facilitates the setting of the solder 002 on the first mounting surface 021. Optionally, the first fixture 010 also has a first working groove 023. The first slot 011 is located in the first working groove 023. When the heat dissipation substrate 020 is arranged in the first slot 011, a first accommodating cavity is formed between the inner wall of the first working groove 023 and the heat dissipation substrate 020. The first accommodating cavity can accommodate the overflowed liquid solder 002, reducing the risk of the liquid solder 002 spreading outside the first fixture 010. Optionally, the first mounting surface 021 of the heat dissipation substrate 020 is further provided with a plurality of mounting grooves 025. The mounting grooves 025 are used to correspond to the heat dissipation extension member 040. It can be understood that, as Figure 8 As shown, the first mounting surface 021 may not be provided with the mounting groove 025 , and the heat dissipation extension member 040 directly contacts the flat first mounting surface 021 .

[0145] like Fig. 9 and Fig.10As shown, the second fixture 030 includes a second slot 031. The number of the second slots 031 can be multiple. The second slot 031 is used to clamp the heat dissipation extension 040. The heat dissipation extension 040 can be a heat dissipation fin made of copper, or it can be other structures such as a heat dissipation cylinder, a heat dissipation square column, etc. The heat dissipation extension 040 has a second mounting surface 041 along the mounting direction X. Along the mounting direction X, the depth of the second slot 031 is less than the thickness of the heat dissipation extension 040, so that when the heat dissipation extension 040 is inserted into the second slot 031, the second mounting surface 041 can extend out of the second slot 031. The second mounting surface 041 extends out of the second slot 031, which facilitates the setting of the solder 002 on the second mounting surface 041. Optionally, the second fixture 030 also has a second working groove 033. The second slot 031 is located in the second working groove 033. When the heat dissipation extension 040 is arranged in the second card slot 031, a second accommodating chamber is formed between the inner wall of the second working groove 033 and the heat dissipation extension 040. The second accommodating chamber can accommodate the overflowed liquid solder 002, reducing the risk of the liquid solder 002 diffusing to the outside of the second fixture 030. Optionally, the second card slot 031 can penetrate the second fixture 030 along the installation direction X, so that both ends of the heat dissipation extension 040 along the installation direction X extend out of the second fixture 030. The end of the heat dissipation extension 040 that faces away from the second mounting surface 041 is the force-bearing surface 043. It can be understood that the second fixture 030 can be designed in a split type. The second fixture 030 is divided into two parts, each part abuts against one side of the heat dissipation extension 040, and the two parts are assembled to clamp the heat dissipation extension 040.

[0146] Please return to Figure 5, the first fixture 010 is provided with a first assembly portion 015 extending along the installation direction X, and the second fixture 030 is provided with a second assembly portion 035 extending along the installation direction X. The working piece 050 is provided at one end of the second fixture 030 away from the first fixture 010. The working piece 050 is provided with a third assembly portion 051 extending along the installation direction X. The first fixture 010, the second fixture 030 and the working piece 050 are connected along the installation direction X by matching the first assembly portion 015, the second assembly portion 035 and the third assembly portion 051 through the assembly part 060 extending along the installation direction X, and the first fixture 010, the second fixture 030 and the working piece 050 can move relative to each other along the installation direction X. Optionally, the first assembly portion 015 is a threaded hole, the second assembly portion 035 is a through hole, and the third assembly portion 051 is a through hole. The assembly part 060 is a bolt, and the bolt passes through the third assembly portion 051 and the second assembly portion 035, and is threadedly matched with the first assembly portion 015. The first fixture 010 and the assembly part 060 are relatively fixedly connected, and the second fixture 030 and the working piece 050 can move relative to the assembly part 060 along the installation direction X, so that the second fixture 030 and the working piece 050 can move relative to the first fixture 010 along the installation direction X, and the second fixture 030 can move relative to the first fixture 010 along the installation direction X. An ultrasonic tool head 070 is arranged at one end of the working piece 050 away from the second fixture 030, and the ultrasonic tool head 070 drives the working piece 050 and the second fixture 030 (and the heat dissipation extension 040) to vibrate relative to the first fixture 010 (and the heat dissipation substrate 020) along the installation direction X, so that ultrasonic energy can be applied between the heat dissipation extension 040 and the heat dissipation substrate 020, so that the solder 002 between the first fixture 010 and the second fixture 030 is melted. It is understandable that the diameter of the second assembly part 035 and the diameter of the third assembly part 051 can also be greater than the diameter of the assembly part 060, so that the first fixture 010 and the working piece 050 can also vibrate relative to the first fixture 010 perpendicular to the installation direction X. It is understandable that if the second slot 031 is penetrated, the working piece 050 can directly abut against the force-bearing surface 043 of the heat dissipation extension 040, thereby driving the heat dissipation extension 040 to vibrate relative to the heat dissipation substrate 020. If the second slot 031 is not penetrated, the working piece 050 can abut against the second fixture 030, and drive the heat dissipation extension 040 to vibrate relative to the heat dissipation substrate 020 through the second fixture 030. It is understandable that if the assembly part 060 is not provided, the third assembly part 051 can be provided in other forms, for example, the third assembly part 051 can be provided as an insertion rod, and the insertion rod is inserted into the first assembly part 015 and the second assembly part 035, so as to limit the relative positions of the working piece 050, the first fixture 010 and the second fixture 030.

[0147] It can be understood that the working piece 050 can also be disposed at an end of the first fixture 010 away from the second fixture 030. By driving the first fixture 010 and the working piece 050 to vibrate relative to the second fixture 030.

[0148] Optionally, the fixture assembly 001 further includes a preheating member 080. The preheating member 080 is disposed at one end of the first fixture 010 away from the second fixture 030. The preheating member 080 can heat the first fixture 010 and the heat dissipation substrate 020, so that

[0149] It should be noted that one of the heat dissipation extension piece 040 and the heat dissipation substrate 020 needs to extend out of the working groove so that the heat dissipation extension piece 040 and the heat dissipation substrate 020 can contact each other. That is, the heat dissipation substrate 020 extends out of the first working groove 023 along the installation direction X, and / or the heat dissipation extension piece 040 extends out of the second working groove 033 along the installation direction X. Specifically, the dimension of the heat dissipation substrate 020 extending out of the first working groove 023 along the installation direction X can be 2 to 3 mm.

[0150] Using the fixture assembly 001 in conjunction with the ultrasonic tool head 070, the IGBT heat sink preparation method includes:

[0151] S101 , the heat dissipation substrate 020 is clamped by the first clamp 010 , and the first mounting surface 021 of the heat dissipation substrate 020 is exposed along the mounting direction X from the first clamp 010 .

[0152] S102 , clamping the heat dissipation extension member 040 by the second clamp 030 , and the second installation surface 041 of the heat dissipation extension member 040 along the installation direction X is exposed from the second clamp 030 .

[0153] S103, aligning the first fixture 010 and the second fixture 030 so that in a projection plane perpendicular to the installation direction X, the second installation surface 041 is located inside the first installation surface 021, and the second fixture 030 and the first fixture 010 are movably matched along the installation direction X.

[0154] S104 a , placing the solder 002 on the first mounting surface 021 , and heating the heat dissipation substrate 020 to a temperature 20 to 50° C. above the melting point of the solder 002 .

[0155] S105, using the ultrasonic tool head 070 to apply ultrasonic waves to the solder 002, so that the solder 002 melts and wets the heat dissipation substrate 020 and the heat dissipation extension 040. Optionally, the ultrasonic frequency is 20 to 60 KHz, the ultrasonic amplitude is 5 to 15 microns, and the ultrasonic power is 500 to 3000 watts.

[0156] S107 , stop applying ultrasonic waves to the solder 002 , and the melted solder 002 solidifies to solder and fix the heat dissipation substrate 020 and the heat dissipation extension 040 .

[0157] S109 , detaching the first clamp 010 from the heat dissipation substrate 020 , and detaching the second clamp 030 from the heat dissipation extension 040 .

[0158] In step S101: the first mounting surface 021 extends out of the first fixture 010 by 2 to 5 mm along the mounting direction X. The first mounting surface 021 extends out to facilitate the solder 002 to be arranged on the first mounting surface 021. The first mounting surface 021 extends out by 2 to 5 mm, which, on the one hand, allows a sufficiently large area of ​​the heat dissipation substrate 020 to be clamped by the fixture to maintain stability, and on the other hand, allows the heat dissipation substrate 020 to expose a sufficient area to be wetted by the molten solder 002.

[0159] In step S102: the second mounting surface 041 extends out of the second fixture 030 by 2 to 5 mm along the mounting direction X. The second mounting surface 041 extends out, so that the solder 002 can be arranged on the second mounting surface 041. The extension of the second mounting surface 041 by 2 to 5 mm can, on the one hand, allow a sufficiently large area of ​​the heat dissipation extension 040 to be clamped by the fixture to maintain stability, and on the other hand, allow a sufficient area of ​​the heat dissipation extension 040 to be exposed to be wetted by the molten solder 002.

[0160] It can be understood that the first mounting surface 021 extending out of the first fixture 010 and the second mounting surface 041 extending out of the second fixture 030 can exist simultaneously, so that both the first mounting surface 021 and the second mounting surface 041 are convenient for setting the solder 002 .

[0161] Step S104a includes:

[0162] S104a1, placing a solder 002 block on the first mounting surface 021, and using an ultrasonic tool head 070 to act on the solder 002 block, so that the solder 002 block is melted and laid on the first mounting surface 021. Optionally, Figure 7 As shown, the ultrasonic tool head 070 is driven by the moving device to move parallel to the first mounting surface 021 .

[0163] Step S104a may also be replaced by:

[0164] S104b, placing the solder 002 on the second mounting surface 041 , and heating the heat dissipation extension member 040 to a temperature 20 to 50° C. above the melting point of the solder 002 .

[0165] Step S104b includes:

[0166] S104b1, place the solder 002 sheet on the second mounting surface 041, and use the ultrasonic tool head 070 to act on the solder 002 sheet, so that the solder 002 sheet is melted and laid on the second mounting surface 041. Optionally, the ultrasonic tool head 070 is driven by a moving device to move parallel to the second mounting surface 041.

[0167] It is understandable that S104a and S104b may also exist simultaneously in one IGBT heat sink manufacturing method, so that the solder 002 is disposed on both the first mounting surface 021 and the second mounting surface 041 .

[0168] Before step S106, the method further includes:

[0169] S106, placing the heat dissipation substrate 020, the heat dissipation extension 040 and the melted solder 002 in an inert gas environment, wherein the inert gas includes at least one of nitrogen, argon and helium.

[0170] After step S106, the method further includes:

[0171] S1081, control the welding gap between the heat dissipation substrate 020 and the heat dissipation extension 040 to have a preset width, and fill the welding gap with the melted solder 002. Optionally, the preset width can be 2 to 3 mm, so that when the ultrasonic tool applies ultrasonic waves, the heat dissipation substrate 020 and the heat dissipation extension 040 can have a relative movement amplitude of 2 to 3 mm, reduce interference with ultrasonic vibration, and thus facilitate melting of the solder 002.

[0172] S1082, remove at least part of the melted solder 002 outside the welding gap. Optionally, before the solder 002 solidifies, excess solder 002 can be removed by means of a scraper or a solder sucker, so that a solder 002 layer of 0.2 to 1 mm is reserved on the first mounting surface 021 and the second mounting surface 041.

[0173] A relatively complete IGBT heat sink manufacturing method includes:

[0174] S101 , clamping the heat dissipation substrate 020 by the first clamp 010 , and the first mounting surface 021 of the heat dissipation substrate 020 is exposed from the first clamp 010 along the mounting direction X. The first mounting surface 021 protrudes from the first clamp 010 along the mounting direction X by 2 mm.

[0175] S102, clamp the heat dissipation extension member 040 by the second clamp 030, and the second mounting surface 041 of the heat dissipation extension member 040 is exposed from the second clamp 030 along the mounting direction X. The second mounting surface 041 protrudes from the second clamp 030 along the mounting direction X by 2 mm.

[0176] S103, aligning the first fixture 010 and the second fixture 030 so that in a projection plane perpendicular to the installation direction X, the second installation surface 041 is located inside the first installation surface 021, and the second fixture 030 and the first fixture 010 are movably matched along the installation direction X.

[0177] S104, the solder 002 is placed on the first mounting surface 021, and the ultrasonic tool head 070 is used to act on the solder 002 block, so that the solder 002 block is melted and laid on the first mounting surface 021. The solder 002 is placed on the second mounting surface 041, and the ultrasonic tool head 070 is used to act on the solder 002 sheet, so that the solder 002 sheet is melted and laid on the second mounting surface 041.

[0178] S105, using the ultrasonic tool head 070 to apply ultrasonic waves to the solder 002, so that the solder 002 melts and wets the heat dissipation substrate 020 and the heat dissipation extension 040. The ultrasonic frequency is 40KHz, the ultrasonic amplitude is 10 microns, and the ultrasonic power is 2000 watts.

[0179] S106, placing the heat dissipation substrate 020, the heat dissipation extension 040 and the melted solder 002 in an inert gas environment, wherein the inert gas includes argon gas.

[0180] S107 , stop applying ultrasonic waves to the solder 002 , and the melted solder 002 solidifies to solder and fix the heat dissipation substrate 020 and the heat dissipation extension 040 .

[0181] S1081, controlling a welding gap with a preset width of 2 mm between the heat dissipation substrate 020 and the heat dissipation extension 040, and filling the welding gap with molten solder 002.

[0182] S1082, before the solder 002 is solidified, use a scraper to remove excess solder 002, so that a solder 002 layer of 0.5 mm is reserved on the first mounting surface 021 and the second mounting surface 041.

[0183] S109 , after the solder 002 is solidified, the first clamp 010 is detached from the heat dissipation substrate 020 , and the second clamp 030 is detached from the heat dissipation extension 040 .

[0184] The above relatively complete IGBT heat sink manufacturing method is respectively applied using A2, B2, C2 and D2 solders 002 to obtain corresponding welding structures.

[0185] Fig.11 The interface microstructure of the welding structure on the heat dissipation substrate 020 side obtained by using the A2 solder 002 and applying the above relatively complete IGBT heat sink manufacturing method is shown.

[0186] like Fig.11As shown, a dense compound layer with a thickness of about 2 microns is formed at the solder 002 and the heat dissipation substrate 020. The solder 002 and the heat dissipation substrate 020 have high fusion properties and few gaps and cracks. On the one hand, the connection strength between the solder 002 and the heat dissipation substrate 020 can be improved, and on the other hand, the decrease in thermal conductivity caused by gaps and cracks can be reduced. The connection strength between the heat dissipation substrate 020 and the heat dissipation extension 040 in the IGBT heat sink can be improved, and the negative impact on the heat dissipation performance of the IGBT heat sink can also be reduced.

[0187] Fig.12 The interface microstructure of the welding structure on the heat dissipation substrate 020 side obtained by using the B2 solder 002 and applying the above relatively complete IGBT heat sink manufacturing method is shown.

[0188] like Fig.12 As shown, a dense compound layer with a thickness of about 1 micron is formed at the solder 002 and the heat dissipation substrate 020. The solder 002 and the heat dissipation substrate 020 have high fusion properties and few gaps and cracks. On the one hand, the connection strength between the solder 002 and the heat dissipation substrate 020 can be improved, and on the other hand, the decrease in thermal conductivity caused by gaps and cracks can be reduced. The connection strength between the heat dissipation substrate 020 and the heat dissipation extension 040 in the IGBT heat sink can be improved, and the negative impact on the heat dissipation performance of the IGBT heat sink can also be reduced.

[0189] Fig.13 The interface microstructure of the welding structure on the heat dissipation substrate 020 side obtained by using the C2 solder 002 and applying the above relatively complete IGBT heat sink manufacturing method is shown.

[0190] like Fig.13 As shown, a dense compound layer with a thickness of about 1 micron is formed at the solder 002 and the heat dissipation substrate 020. The solder 002 and the heat dissipation substrate 020 have high fusion properties and few gaps and cracks. On the one hand, the connection strength between the solder 002 and the heat dissipation substrate 020 can be improved, and on the other hand, the decrease in thermal conductivity caused by gaps and cracks can be reduced. The connection strength between the heat dissipation substrate 020 and the heat dissipation extension 040 in the IGBT heat sink can be improved, and the negative impact on the heat dissipation performance of the IGBT heat sink can also be reduced.

[0191] Fig.14 The interface microstructure of the welding structure on the heat dissipation substrate 020 side obtained by using the D2 solder 002 and applying the above relatively complete IGBT heat sink manufacturing method is shown.

[0192] like Fig.14As shown, a dense compound layer with a thickness of about 0.5 microns is formed at the solder 002 and the heat dissipation substrate 020. The solder 002 and the heat dissipation substrate 020 have high fusion properties and few gaps and cracks. On the one hand, the connection strength between the solder 002 and the heat dissipation substrate 020 can be improved, and on the other hand, the decrease in thermal conductivity caused by gaps and cracks can be reduced. The connection strength between the heat dissipation substrate 020 and the heat dissipation extension 040 in the IGBT heat sink can be improved, and the negative impact on the heat dissipation performance of the IGBT heat sink can also be reduced.

[0193] From X1, X2, X3 and X4, since the IGBT heat sink itself is not a force-bearing structure, even the relatively weak D2 solder 002 can meet the strength requirements of the IGBT heat sink, and the melting point of D2 solder 002 is close to 500°C, which is also convenient for the subsequent packaging process of the IGBT heat sink, making the packaging process more selective. The melting temperature of D2 solder 002 is lower than 500°C, and it is not easy to cause the heat dissipation substrate 020 of the IGBT heat sink to become soft and not meet the requirements of the IGBT heat sink during the melting process of D2 solder 002.

[0194] In summary, the solder provided in the present application can control the melting point between 300 and 500°C, satisfying the subsequent packaging process of the IGBT heat sink, and maintaining the performance of the IGBT heat sink itself. The solder preparation method provided in the present application can stably produce the above solder and maintain the stability of the solder performance. The IGBT heat sink manufacturing method provided in the present application utilizes the performance of the above solder, and can improve the yield of the IGBT heat sink compared to the process of directly forming all the cooling fins of the IGBT heat sink by cold forging or hot forging stamping.

[0195] The above description is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the disclosure scope of the present application.

Claims

1. A solder, characterized in that: The mass percentage of Sn in the solder is less than 0.1%: The solder comprises, by weight: 90.3 to 96.8 parts of Zn and 2.5 to 3.2 parts of Ag; The solder also includes a metal auxiliary component, and the metal auxiliary component is: Cu 0.4-0.5 parts; Or, Cu 0.4-0.5 parts, Al 5.2-5.5 parts; Or, Al 2.1 to 5.8 parts, Ni 0.7 to 0.9 parts.

2. The solder according to claim 1, characterized in that The mass percentage of In in the solder is less than 0.1%.

3. The solder according to claim 1, characterized in that: When the metal auxiliary component is 0.4-0.5 parts of Cu, the mass ratio of Zn, Ag and Cu in the solder is (96.5-96.8): (2.8-3.0): (0.4-0.5); When the metal auxiliary component is 0.4-0.5 parts of Cu and 5.2-5.5 parts of Al, the mass ratio of Zn, Ag, Cu and Al in the solder is (91.2-91.7): (2.5-2.8): (0.4-0.5): (5.2-5.5); When the metal auxiliary components are 2.1 to 5.8 parts of Al and 0.7 to 0.9 parts of Ni, the mass ratio of Zn, Ag, Al and Ni in the solder is (93.7 to 94.0): (2.9 to 3.1): (2.1 to 2.3): (0.8 to 0.9), or the mass ratio of Zn, Ag, Al and Ni in the solder is (90.3 to 90.7): (3.1 to 3.2): (5.3 to 5.8): (0.7 to 0.9).

4. The solder according to claim 3, characterized in that: When the metal auxiliary component is 0.4-0.5 parts of Cu, the mass ratio of Zn, Ag and Cu in the solder is 96.6:2.9:0.5; When the metal auxiliary component is 0.4-0.5 parts of Cu and 5.2-5.5 parts of Al, the mass ratio of Zn, Ag, Cu and Al in the solder is 91.5:2.7:0.4:5.4; When the metal auxiliary components are 2.1-5.8 parts of Al and 0.7-0.9 parts of Ni, the mass ratio of Zn, Ag, Al and Ni in the solder is 93.9:3.1:2.1:0.9, or the mass ratio of Zn, Ag, Al and Ni in the solder is 90.5:3.2:5.4:0.

9.

5. A method for preparing solder, characterized in that: Used for preparing the brazing filler metal according to any one of claims 1 to 4, the brazing filler metal preparation method comprising: Mixing the master alloy and adding a covering agent, and placing the master alloy in a heating chamber at a first temperature for heating until the master alloy is completely melted to form a molten metal; The temperature of the heating chamber is raised to a second temperature, and the molten metal in the heating chamber is kept warm for more than 100 minutes; The temperature of the heating chamber is lowered to a third temperature, and the molten metal in the heating chamber is kept warm for more than 20 minutes; Placing the molten metal in a cooling environment of 15 to 40° C. until the molten metal forms a solid material, and the temperature difference between the solid material and the cooling environment is less than 50° C.; The covering agent on the solid material is removed.

6. The method for preparing solder according to claim 5, characterized in that: The covering agent includes at least one of lithium chloride and potassium chloride.

7. The method for preparing solder according to claim 5, characterized in that: The first temperature is between 580 and 620° C., the second temperature is between 630 and 670° C., the third temperature is between 580 and 620° C., and the second temperature is greater than the first temperature and the second temperature.

8. The method for preparing solder according to claim 5, characterized in that: In the step of cooling the temperature of the heating chamber to the third temperature and keeping the molten metal in the heating chamber warm for more than 20 minutes, The molten metal was stirred at least 5 times every 8 to 12 minutes using a stirring rod.

9. A method for manufacturing an IGBT heat sink, characterized in that: The method of preparing an IGBT heat sink using the solder according to any one of claims 1 to 4 or the solder prepared by the solder preparation method according to any one of claims 5 to 8 comprises: The heat dissipation substrate is clamped by a first clamp, and a first mounting surface of the heat dissipation substrate is exposed from the first clamp along a mounting direction; The heat dissipation extension member is clamped by a second clamp, and the second mounting surface of the heat dissipation extension member is exposed from the second clamp along the mounting direction; Aligning the first fixture and the second fixture so that the second mounting surface is located inside the first mounting surface in a projection plane perpendicular to the mounting direction, and the second fixture and the first fixture are movably matched along the mounting direction; The solder is arranged on the first mounting surface, and the heat dissipation substrate is heated to 20 to 50° C. above the melting point of the solder, and / or the solder is arranged on the second mounting surface, and the heat dissipation extension is heated to 20 to 50° C. above the melting point of the solder; Applying ultrasonic waves to the solder using an ultrasonic tool head, so that the solder melts and wets the heat dissipation substrate and the heat dissipation extension; Stop applying ultrasonic waves to the solder, so that the melted solder solidifies to fix the heat dissipation substrate and the heat dissipation extension member by welding; The first clamp is detached from the heat dissipation substrate, and the second clamp is detached from the heat dissipation extension.

10. The method for manufacturing an IGBT heat sink according to claim 9, characterized in that: After the step of stopping applying ultrasonic waves to the solder, the method further comprises: Controlling a welding gap with a preset width between the heat dissipation substrate and the heat dissipation extension member, and filling the welding gap with the melted solder; At least a portion of the melted solder outside the welding gap is removed.

11. The method for manufacturing an IGBT heat sink according to claim 9, characterized in that: Before the molten brazing material solidifies to fix the heat dissipation substrate and the heat dissipation extension by welding, the method further comprises: The heat dissipation substrate, the heat dissipation extension and the melted solder are placed in an inert gas environment, wherein the inert gas includes at least one of nitrogen, argon and helium.

12. The method for manufacturing an IGBT heat sink according to claim 9, characterized in that: In the step of exposing the first fixture on the first mounting surface of the heat dissipation substrate along the mounting direction: the first mounting surface protrudes from the first fixture by 2 to 5 mm along the mounting direction; and / or, In the step of exposing the second clamp from the second mounting surface of the heat dissipation extension member along the mounting direction: a dimension of the second mounting surface extending out of the second clamp along the mounting direction is 2 to 5 mm.

Images