Inverter module heat dissipation substrate structure and manufacturing process

Abstract

The structure comprises an upper end cover, a lower end cover and a water channel layer between the upper end cover and the lower end cover, holes are formed in the two ends of the lower end cover to serve as a water inlet and a water outlet respectively, and double-layer graphene is manufactured on the upper surface of the lower end cover; the water channel layer is internally provided with a plurality of water channels arranged side by side along the long edge of the heat dissipation substrate, one end of each water channel is located above the water inlet and communicated with the water inlet, and the other end of each water channel is located above the water outlet and communicated with the water outlet; double-layer graphene is manufactured on the lower surface of the upper end cover, and one or more welding areas are arranged on the upper surface of the upper end cover and used for installing an inversion module. The heat dissipation substrate is manufactured based on the instantaneous liquid phase diffusion welding technology, copper foils with the surfaces covered with graphene are placed between the lower end cover and the water channel layer and between the water channel layer and the upper end cover to serve as middle layers, and therefore the reliability and the heat conduction characteristic of the heat dissipation substrate structure are further improved.

Description

Technical Field

[0001] The present invention specifically relates to the technical field of heat dissipation substrate manufacturing, and in particular to a structure and manufacturing process of a heat dissipation substrate of an inverter module. Background Art

[0002] With the rapid development and widespread application of new energy technologies, the market demand for inverter modules is increasing, especially the development of high-power inverter modules, which also puts forward higher requirements for their thermal management structure. The current mainstream thermal management structure is direct cooling, which connects the inverter module directly to the heat dissipation substrate. The heat dissipation substrate has flat plate type, pin-fin type, etc., and installs a water cooling box to take away the high heat generated by the inverter module during operation by fluid heat transfer and dissipate it to the surrounding environment.

[0003] At present, the processing technology of heat dissipation substrate is mainly cold forging. Although the products of this process have good surface quality and high dimensional accuracy, with the changes in the packaging structure of the inverter module, the cold forging process steps in the development and modification of new products of heat dissipation substrate take a long time, and the mold cost is relatively high. For the situation of a large number of product specifications, small batch production and urgent need for parts, it is urgent to find a production process with efficient and economical price to choose from. Summary of the invention

[0004] The object of the present invention is to provide a structure and a manufacturing process of a heat dissipation substrate of an inverter module, so as to solve or partially solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention proposes a manufacturing process of an inverter module heat dissipation substrate, the steps of which include:

[0006] Step 1: Use a CNC lathe to process the copper materials of the lower end cover, water channel layer and upper end cover according to the size of the drawing for use, wherein long holes are processed at both ends of the lower end cover, and multiple hollow water channels along the long side direction of the heat dissipation substrate are processed in the water channel layer; in addition, the copper foil processed to be consistent with the shape of the upper end cover is called a non-grooved copper foil, and the copper foil processed to be consistent with the shape of the lower end cover and having holes corresponding to the long holes at both ends is called a grooved copper foil;

[0007] Step 2: growing double-layer graphene on one side of the copper foil without grooves and the copper foil with grooves respectively by chemical vapor deposition to obtain the copper foil without grooves and the copper foil with grooves;

[0008] Step 3: stack the lower end cover with a cleaned surface, the grooved graphene copper foil, the water channel layer, the non-grooved graphene copper foil, and the upper end cover in sequence, wherein the graphene of the grooved graphene copper foil faces upward, and the graphene of the non-grooved graphene copper foil faces downward; one end of the water channel corresponds to the position of the long hole at one end of the lower end cover, and the other end of the water channel corresponds to the position of the long hole at the other end of the lower end cover;

[0009] Step 4: Use a fixture to fix the stacked structure to a diffusion welding machine, and generate heat through current conduction. Diffusion reaction occurs between the layers under temperature and pressure to form a tight connection;

[0010] Step 5: After cooling, remove the heat dissipation substrate of the stacked structure, process the mounting holes according to the size of the inverter module, and make the welding area on the surface of the upper end cover.

[0011] The present invention also proposes a heat dissipation substrate structure of an inverter module. The substrate is rectangular in shape, and its structure includes an upper end cover, a lower end cover and a water channel layer therebetween. The openings at both ends of the lower end cover serve as a water inlet and a water outlet respectively, and a double-layer graphene is made on the upper surface of the lower end cover; the water channel layer has a plurality of water channels arranged side by side along the long side of the heat dissipation substrate, one end of the water channel is located above the water inlet and connected to the water inlet, and the other end of the water channel is located above the water outlet and connected to the water outlet; the lower surface of the upper end cover is made of a double-layer graphene, and one or more welding areas are provided on the upper surface of the upper end cover for installing the inverter module.

[0012] Specifically, the water channel can be made into a corrugated shape.

[0013] Specifically, the base materials of the upper end cover, the lower end cover and the water channel layer are all copper.

[0014] Specifically, the upper end cover and the lower end cover have the same thickness, which is 1±0.1 mm, the water channel layer has a thickness of 3±0.1 mm, the water channel width is 2.4±0.05 mm, and the distance between adjacent water channels is 3±0.05 mm.

[0015] The upper surface of the upper end cover is provided with different numbers of welding areas according to the topological structure of the inverter module. A half-bridge inverter module corresponds to 1 welding area, a full-bridge inverter module corresponds to 2 welding areas, and a three-phase bridge inverter module corresponds to 3 welding areas.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention adopts CNC technology to process the single-layer structure of the heat dissipation substrate, namely the lower end cover, the water channel layer and the upper end cover, and then uses diffusion welding technology to make the multi-layer structure form a fastened connection under appropriate temperature and pressure, which can realize the complex structural design and processing of the water channel layer, while reducing mold costs and improving production efficiency.

[0018] 2. The present invention uses a double-layer graphene-covered copper foil as the intermediate layer of diffusion welding. On the one hand, it can prevent the lower surface of the upper end cover and the upper surface of the lower end cover from being corroded during the flow of the coolant, thereby affecting the heat dissipation performance. On the other hand, the high lateral thermal conductivity of graphene can be used to achieve uniform heat dissipation of the entire heat dissipation substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a top view of the heat dissipation substrate of the inverter module proposed by the present invention.

[0020] Figure 2 This is a bottom view of the lower end cover of the heat dissipation substrate proposed by the present invention.

[0021] Figure 3 This is a schematic diagram of the water channel layer structure of the heat dissipation substrate proposed by the present invention.

[0022] Figure 4 Schematic diagram of the external structure of the heat dissipation substrate of the three-phase bridge inverter module in an embodiment of the present invention.

[0023] Figure 5 Schematic diagram of the structure of the grooveless graphene copper foil produced in step 2 of the embodiment of the present invention.

[0024] Figure 6 Schematic diagram of the structure of the grooved graphene copper foil produced in step 2 of the embodiment of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments of the present invention.

[0026] In an embodiment of the present invention, a heat dissipation substrate of an inverter module has a structure as follows: Figure 1 As shown in FIG. 4 , the structure includes three main parts from bottom to top: a lower end cover 10, a water channel layer 11 and an upper end cover 12. The three main parts are all rectangular and have the same plane size. They are stacked in sequence with the same longitudinal axis as the center.

[0027] The two openings at the lower end cover 10 are used as a water inlet 21 and a water outlet 22, respectively. Figure 2 The upper surface of the lower end cover 10 is made of double-layer graphene, and the lower surface of the upper end cover 12 is made of double-layer graphene.

[0028] The water channel layer 11 has a plurality of hollow water channels 31 arranged side by side along the long side of the heat dissipation substrate. The water channels 31 in the embodiment are of corrugated type, such as Figure 3 As shown. The starting position of the water channel 31 corresponds to the upper part of the water inlet 21 of the lower end cover, and the ending position corresponds to the upper part of the water outlet 22 of the lower end cover. The width of the water channel is 2.4±0.05mm, and the distance between adjacent water channels is 3±0.05mm.

[0029] The upper surface of the upper end cover 12 is provided with welding areas along the long side direction. Different numbers of welding areas are provided according to the topological structure of the inverter module. A half-bridge inverter module corresponds to one welding area, and a full-bridge inverter module corresponds to two welding areas. Figure 4 Taking the three-phase bridge inverter module as an example, there are 3 welding areas, corresponding to the U, V, and W phases of the inverter module respectively.

[0030] The present application also provides a manufacturing process of an inverter module heat dissipation substrate based on the above structure, the process comprising the following steps:

[0031] Step 1: Use a CNC lathe to process the copper materials of the lower end cover 10, the water channel layer 11 and the upper end cover 12 according to the dimensions of the drawing for later use.

[0032] Among them, long holes are processed at both ends of the lower end cover 10, which serve as the water inlet 21 and the water outlet 22 respectively; and a corrugated water channel 31 along the long side direction is processed on the water channel layer 11. The above processing can be automatically completed by a CNC punching machine according to a preset program, and only a simple mold combination is required. Compared with traditional stamping, a large amount of mold costs are saved, the cost is low, and the cycle is short.

[0033] In addition, a laser cutting machine is used to process copper foil with the same shape as the upper and lower end covers for use. The copper foil with the same shape as the upper end cover is called grooveless copper foil, and the copper foil with the same shape as the lower end cover also has holes at the positions of the long holes at both ends of the lower end cover, which is called grooved copper foil.

[0034] The thickness of the lower end cover and the upper end cover is the same, about 1mm, with a tolerance of ±0.1mm; the thickness of the water channel layer is about 3mm, with a tolerance of ±0.1mm; the thickness of the copper foil as the middle layer is about 25μm.

[0035] Step 2: Under high temperature and high pressure, the copper foil can catalyze the decomposition of carbon source gases such as methane, and deposit on the surface of the copper foil to form a graphene layer. By using a chemical vapor deposition method, a copper foil without grooves 50 and a copper foil with grooves 51 are used as substrates, and by optimizing the growth conditions, controlling the methane gas flow rate and the growth time, a double-layer graphene 52 is produced on the surface of the copper foil, and a copper foil without grooves and a copper foil with grooves are obtained for use. Figure 5 and Figure 6 shown.

[0036] Step 3: Stack the lower end cover 10 with cleaned surface, the grooved copper foil 51, the water channel layer 11, the grooveless copper foil 50, and the upper end cover 12 in sequence, with the graphene of the grooved copper foil 51 facing upward and the graphene of the grooveless copper foil 50 facing downward, so that the double-layer graphene is exposed on both sides of the water channel and directly contacts with the coolant in the water channel when used in the future.

[0037] During the subsequent use of the heat dissipation substrate, as the coolant slowly evaporates and chemically reacts, its pH value will change, which will cause corrosion of the copper substrate, thereby affecting the heat dissipation effect. The double-layer graphene 52 has a doping mechanism with different sides. The outer layer of graphene is almost undoped and close to electrical neutrality, which effectively inhibits the occurrence of surface electrochemical reactions. The inner layer of graphene has more charge transfer and stronger interaction with copper, which makes the interface diffusion of corrosive molecules more difficult, and can protect the lower surface of the upper end cover 12 and the upper surface of the lower end cover 10 from corrosion. On the other hand, because the double-layer graphene 52 has a very high lateral heat conduction capacity, the heat of the heat dissipation substrate in the plane can be more evenly distributed, reducing the temperature difference between the phases of the inverter module and improving the working reliability of the module.

[0038] Step 4: Use a fixture to fix the above stacked structure to the diffusion welding machine, and conduct current to heat the copper parts to ensure uniform heating effect. During the heating process, the temperature of the copper stacked structure heat dissipation substrate rises. The copper foil has a lower melting point than the copper upper end cover, lower end cover and water channel layer, and melts first to form an instantaneous liquid film on the joint surface; in the subsequent insulation process, diffusion reactions occur between the layers under temperature and pressure, and they penetrate each other to form a tight connection.

[0039] Step 5: After the connection area is cooled, remove the fixtures and other fixing devices, take down the heat dissipation substrate of the multi-layer stacked structure, process a corresponding number of mounting holes according to the size of the inverter module, and make welding areas 41 on the surface of the upper end cover 12 corresponding to the number of the inverter module topology structure.

[0040] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. An inverter module heat dissipation substrate structure, the substrate is rectangular in shape, characterized in that: The heat dissipation substrate comprises an upper end cover (12), a lower end cover (10) and a water channel layer (11) therebetween; the lower end cover (10) has openings at both ends serving as a water inlet (21) and a water outlet (22) respectively; the upper surface of the lower end cover (10) is provided with a double-layer graphene; the water channel layer (11) comprises a plurality of water channels (31) arranged side by side along the long side of the heat dissipation substrate; one end of the water channel (31) is located above the water inlet (21) and communicates with the water inlet (21); the other end of the water channel (31) is located above the water outlet (22) and communicates with the water outlet (22); the lower surface of the upper end cover (12) is provided with a double-layer graphene; the upper surface of the upper end cover (12) is provided with one or more welding areas for mounting an inverter module.

2. The inverter module heat dissipation substrate structure according to claim 1, characterized in that: The water channel (31) is of a corrugated type.

3. The inverter module heat dissipation substrate structure according to claim 1, characterized in that: The base materials of the upper end cover (12), the lower end cover (10) and the water channel layer (11) are all copper.

4. The inverter module heat dissipation substrate structure according to claim 1, characterized in that: The upper end cover (12) and the lower end cover (10) have the same thickness of 1±0.1 mm, and the water channel layer (11) has a thickness of 3±0.1 mm.

5. The inverter module heat dissipation substrate structure according to claim 1, characterized in that: The width of the water channel (31) is 2.4±0.05 mm, and the distance between adjacent water channels is 3±0.05 mm.

6. The inverter module heat dissipation substrate structure according to claim 1, characterized in that: The upper surface of the upper end cover (12) is provided with different numbers of welding areas according to the topological structure of the inverter module, wherein a half-bridge inverter module corresponds to one welding area, a full-bridge inverter module corresponds to two welding areas, and a three-phase bridge inverter module corresponds to three welding areas.

7. A manufacturing process for an inverter module heat dissipation substrate, characterized in that: The following steps are involved: Step 1: Use a CNC lathe to process the copper materials of the lower end cover, water channel layer and upper end cover according to the size of the drawing for use, wherein long holes are processed at both ends of the lower end cover, and multiple hollow water channels along the long side direction of the heat dissipation substrate are processed in the water channel layer; in addition, the copper foil processed to be consistent with the shape of the upper end cover is called a non-grooved copper foil, and the copper foil processed to be consistent with the shape of the lower end cover and having holes corresponding to the long holes at both ends is called a grooved copper foil; Step 2: growing double-layer graphene on one side of the copper foil without grooves and the copper foil with grooves respectively by chemical vapor deposition to obtain the copper foil without grooves and the copper foil with grooves; Step 3: stack the lower end cover with a cleaned surface, the grooved graphene copper foil, the water channel layer, the non-grooved graphene copper foil, and the upper end cover in sequence, wherein the graphene of the grooved graphene copper foil faces upward, and the graphene of the non-grooved graphene copper foil faces downward; one end of the water channel corresponds to the position of the long hole at one end of the lower end cover, and the other end of the water channel corresponds to the position of the long hole at the other end of the lower end cover; Step 4: Use a fixture to fix the stacked structure to a diffusion welding machine, and generate heat through current conduction. Diffusion reaction occurs between the layers under temperature and pressure to form a tight connection; Step 5: After cooling, remove the heat dissipation substrate of the stacked structure, process the mounting holes according to the size of the inverter module, and Make the welding area on the upper end cover surface.

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