Carrier for reflow soldering of flat power module

Abstract

The utility model relates to a carrier for reflow soldering of a flat plate type power module, which comprises a reflow base, the upper surface of the reflow base is provided with an inverted-arch-shaped groove, a metal substrate is placed in the inverted-arch-shaped groove, the radian value of the metal substrate is the same as that of the inverted-arch-shaped groove, a DBC (Direct Bonding Copper) fixing frame is placed above the metal substrate, and the DBC fixing frame is connected with the inverted-arch-shaped groove. A DBC is placed in the DBC fixing frame, the reflow base, the metal substrate and the DBC fixing frame are respectively provided with a first through hole, a second through hole and a third through hole which are corresponding in position, a connecting piece is arranged in the first through hole, the connecting piece sequentially penetrates through the second through hole and the third through hole, and the limitation among the reflow base, the metal substrate and the DBC fixing frame is realized. And a plurality of solder sheets are arranged between the DBC and the metal substrate. The device has the advantages of simple and reasonable structure, high efficiency, safety, practicability, convenience and the like.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor module packaging technology, and relates to a carrier for reflow soldering of flat panel power modules. Background Technology

[0002] Existing flat-panel IGBT module reflow soldering typically uses high-temperature soldering for the heat sink substrate and the ceramic copper-clad board (DBC). Due to the large difference in their coefficients of thermal expansion, the substrate will deform after reflow, leading to poor mounting contact and excessive thermal resistance.

[0003] Existing technologies typically pre-bend the flat substrate to a certain arc to counteract thermal deformation during module soldering, improve the fit of the IGBT module installation, and enhance heat transfer efficiency. During reflow soldering of the IGBT module, heat is conducted from the heating plate to the copper substrate, and then to the solder layer, achieving the soldering of the ceramic copper-clad laminate and the copper substrate. This convex structure means that the copper substrate only contacts the center during heating and cooling, and heat dissipation on the copper substrate is a dissipation pattern from the center outwards. The solder melts at different times, affecting the fluidity of the solder melt, increasing solder porosity, and impacting the module's lifespan.

[0004] To address this issue, a carrier for reflow soldering of flat-panel power modules was designed to overcome the aforementioned problems. Utility Model Content

[0005] The purpose of this invention is to solve the problem of the lack of dedicated HTRB experimental equipment, and to provide a simple, reasonable, efficient, safe, practical and convenient carrier for reflow soldering of flat power modules.

[0006] This utility model is achieved through the following technical solution: a carrier for reflow soldering of flat power modules, including a reflow base, the upper surface of which is provided with an anti-arched groove, a metal substrate placed in the anti-arched groove, the curvature value of which is the same as that of the anti-arched groove, to ensure a tight fit between the metal substrate and the reflow base and to increase the heat-receiving area, a DBC fixing frame placed above the metal substrate, and a DBC placed inside the DBC fixing frame, the reflow base, the metal substrate, and the DBC fixing frame respectively provided with... The first, second, and third through holes are positioned accordingly. A connector is installed in the first through hole, and the connector passes through the second and third through holes in sequence to limit the movement between the reflow base, the metal substrate, and the DBC fixing frame. Multiple solder pieces are placed between the DBC and the metal substrate. After the overall assembly is completed, it is conveyed to the heating platform of the reflow oven via the track. The metal substrate and the DBC fixing frame are pressed and fixed by the fixing and clamping device inside the oven. At the same time, the solder pieces melt as the temperature rises, completing the welding and fixing between the DBC and the metal substrate.

[0007] Preferably, the connector is a pin positioning post, which consists of a pin and a positioning post. The upper diameter of the pin is smaller than the lower diameter. The upper end of the pin has a round head structure, and its lower end is hollow with threads on the inner sidewall. The positioning post has corresponding threads. One end of the positioning post is inserted into the trapezoidal pin and connected by threads, while the other end is embedded in the first through hole of the reflux base and welded or clamped to the reflux base for fixation. The trapezoidal pin is inserted into the second and third through holes in sequence. Its round head structure avoids damage to the second and third through holes when passing through. The trapezoidal structure facilitates assembly, thereby achieving efficient positioning of the metal substrate and the DBC fixing frame.

[0008] Preferably, the lower surface of the reflux base is a plane with a flatness of less than or equal to 0.06, which facilitates placement in the heating platform for welding the metal substrate and the DBC of the DBC fixing frame.

[0009] Preferably, the metal substrate is a copper substrate.

[0010] Preferably, the pin is made of a metal with a hardness less than that of copper to avoid scratching the metal substrate and DBC fixing frame when passing through the second and third through holes.

[0011] Preferably, there are at least two sets of pin positioning posts, with two posts in each set, which are respectively set at the four corners of the center of the return base, thereby ensuring the positioning effect of the metal substrate and the DBC fixing frame.

[0012] Preferably, the reflux base is an aluminum plate.

[0013] The beneficial effects of this utility model are as follows:

[0014] The carrier designed in this utility model for reflow soldering of flat power modules has a reflow base machined into a single-sided groove shape, which increases the heat-receiving area of ​​the copper substrate, reduces the void rate of the copper substrate and DBC during reflow soldering, and improves the reliability of the module. A pin positioning post is added to the reflow base to prevent the copper substrate from shifting from the base after reflow soldering, thereby preventing damage to the module. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the present invention after installation.

[0016] Figure 2 This is a schematic diagram of the reflux base in this utility model.

[0017] Figure 3 This is a schematic diagram of the pin positioning column in this utility model.

[0018] Figure 4 This is a schematic diagram of the structure of the DBC fixing frame in this utility model. Detailed Implementation

[0019] To enable those skilled in the art to more clearly understand the purpose, technical solution and advantages of this utility model, the present utility model will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] In the description of this utility model, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "horizontal", and "vertical" are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0021] The present invention will now be described in detail with reference to the accompanying drawings: Figure 1-2As shown, a carrier for reflow soldering of flat power modules includes a reflow base 1. The upper surface of the reflow base 1 has an inverted arched groove 2. A metal substrate 3 is placed within the inverted arched groove 2, and the curvature of the metal substrate 3 is the same as that of the inverted arched groove 2. This ensures a tight fit between the metal substrate 3 and the reflow base 1 and increases the heat-receiving area. A DBC fixing frame 4 is placed above the metal substrate 3, and a DBC 5 is placed within the DBC fixing frame 4. First channels with corresponding positions are respectively provided on the reflow base 1, the metal substrate 3, and the DBC fixing frame 4. Hole 6, second through hole 7, and third through hole 8 are provided. A connector is provided in the first through hole 6, and the connector passes through the second through hole 7 and the third through hole 8 in sequence to limit the positioning between the reflow base 1, the metal substrate 3, and the DBC fixing frame 4. Multiple solder pieces are placed between the DBC5 and the metal substrate 3. After the overall assembly is completed, it is conveyed to the heating platform of the reflow oven via the track. At the same time, the metal substrate 3 and the DBC5 of the DBC fixing frame 4 are pressed and fixed by the fixing and clamping device inside the oven cavity. The solder pieces melt as the temperature rises, completing the welding and fixing between the DBC5 and the metal substrate 3. The reflow base is an aluminum plate.

[0022] The reflux base in this invention is an aluminum plate. An inverted arched groove with the same curvature as the inverted arched copper substrate is machined on one side of the aluminum plate. The metal substrate is placed in the inverted arched groove. By adopting a form in which the reflux base and the metal substrate are in close contact, the heat-receiving area is increased while heat loss is reduced, and the heating and cooling rate is improved. To a certain extent, this plays a positive role in meeting the basic requirements of quality and quantity production.

[0023] Of course, this utility model can be designed to suit various return bases with different reverse arch curvatures according to actual needs (including but not limited to the flat arc groove mentioned in this preferred embodiment, which can be other arc substrates with PIN pins, and the base can be a flat plate, pinhole, or even hollow, etc.), indicating that the whole has high compatibility, thereby ensuring that when facing various large automotive-grade power modules in the production process, it can cope more flexibly while ensuring production efficiency and quality.

[0024] like Figure 3-4As shown, the pin positioning post consists of a pin 9 and a positioning post 10. The upper diameter of the pin 9 is smaller than the lower diameter. The upper end of the pin is a round-headed structure 11, and its lower end is hollow with threads on the inner sidewall. The positioning post 10 is provided with corresponding threads. One end of the positioning post 10 is inserted into the trapezoidal pin and connected by threads, while the other end is embedded in the first through hole 6 of the return base 1 and welded or clamped to the return base 1. The trapezoidal pin 9 is inserted into the second through hole 7 and the third through hole 8 in sequence. Its round-headed structure 11 avoids damage to the second through hole 7 and the third through hole 8 when passing through. The trapezoidal structure facilitates assembly, thereby achieving efficient positioning of the metal substrate 3 and the DBC fixing frame 4.

[0025] This invention, through the setting of a pin positioning post, can effectively prevent the DBC from shifting due to solder melting during reflow. Furthermore, the diameter of the pin positioning post is smaller than the diameter of the positioning hole on the copper substrate, forming a gap with a gap tolerance requirement of less than 1mm. This ensures that the shaking and movement range of the flat panel power module is within an acceptable range, facilitating its use in automated production lines and improving production efficiency and quality.

[0026] The lower surface of the reflux base 1 is a plane with a flatness of less than or equal to 0.06, which facilitates its placement in the heating platform for welding the metal substrate 3 and the DBC of the DBC fixing frame 4.

[0027] The metal substrate 3 is a copper substrate. The pin 9 is made of a metal with a hardness lower than copper, such as aluminum alloy, to avoid scratching the metal substrate 3 and the DBC fixing frame 4 when passing through the second through hole 7 and the third through hole 8. There are at least two sets of pin positioning posts (a total of 4), which are respectively set at the four corners of the center of the return base to ensure the positioning effect of the metal substrate 3 and the DBC fixing frame 4.

[0028] The working process of this utility model is as follows:

[0029] After assembling the carrier of this utility model according to the figure, the positioning holes of the copper substrate with the anti-arch structure are aligned with the corresponding positioning pins and accurately placed by manual or automatic means. The copper substrate with the anti-arch structure and the heating base with the same curvature value fit tightly together. Then the carrier is conveyed to the heating platform through the track of the reflow oven. The fixing device inside the furnace cavity presses and fixes the outer frame of the carrier. Then the heating plate is slowly lifted and attached to the two aluminum plates for heat transfer heating. The solder reaches the melting point and melts as the temperature rises, realizing the component welding process of the power module (the heating platform, the fixing device inside the furnace cavity, the heating plate, etc. mentioned above are existing technologies, so they will not be described in detail).

[0030] The specific embodiments described herein are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A carrier for reflow soldering of flat power modules, comprising a reflow base (1), characterized in that: The upper surface of the reflow base (1) is provided with an inverted-arch-shaped groove (2), a metal substrate (3) is placed in the inverted-arch-shaped groove (2), the curvature value of the metal substrate (3) is the same as that of the inverted-arch-shaped groove (2), so as to ensure the close fit between the metal substrate (3) and the reflow base (1) and improve the heating area, a DBC fixing frame (4) is placed above the metal substrate (3), the DBC fixing frame (4) is provided with a DBC (5), the reflow base (1), the metal substrate (3) and the DBC fixing frame (4) are respectively provided with a first through hole (6), a second through hole (7) and a third through hole (8) corresponding in position, a connecting piece is arranged in the first through hole (6), the connecting piece passes through the second through hole (7) and the third through hole (8) in sequence, so as to limit the reflow base (1), the metal substrate (3) and the DBC fixing frame (4), a plurality of solder pieces are arranged between the DBC (5) and the metal substrate (3), after the overall assembly is completed, the reflow base is conveyed to the heating platform of the furnace cavity through the track of the reflow furnace, the metal substrate (3) and the DBC (5) of the DBC fixing frame (4) are fixed and pressed by the fixed pressing device inside the furnace cavity, at the same time, the solder pieces melt with the temperature rising, and the welding and fixing between the DBC (5) and the metal substrate (3) are completed.

2. The carrier for reflow soldering of flat power modules according to claim 1, characterized in that The connecting piece is a pin shaft positioning column, the pin shaft positioning column is composed of a pin (9) and a positioning column (10), the upper end diameter of the pin (9) is smaller than the lower end diameter, the upper end of the pin is a round head structure (11), the lower end is hollow inside and is provided with threads on the inner side wall, the positioning column (10) is provided with corresponding threads, one end of the positioning column (10) is inserted into the ladder-shaped pin and is connected through threads, the other end is embedded into the first through hole (6) of the reflow base (1) and is welded and fixed with the reflow base (1) or is clamped and fixed, the ladder-shaped pin (9) is inserted into the second through hole (7) and the third through hole (8) in sequence, the round head structure (11) avoids damaging the second through hole (7) and the third through hole (8) when passing through, the ladder-shaped structure facilitates assembly, so as to realize efficient positioning of the metal substrate (3) and the DBC fixing frame (4).

3. The carrier for reflow soldering of flat power modules according to claim 2, characterized in that: The lower surface of the reflow base (1) is a plane with a flatness less than or equal to 0.06, so as to facilitate placement in the heating platform and welding of the metal substrate (3) and the DBC of the DBC fixing frame (4).

4. The carrier for reflow soldering of flat power modules according to claim 3, characterized in that: The metal substrate (3) is a copper substrate.

5. The carrier for reflow soldering of flat power modules according to claim 2 or 4, characterized in that: The material of the pin (9) is a metal material with a hardness less than that of copper, so as to avoid scratching the metal substrate (3) and the DBC fixing frame (4) when passing through the second through hole (7) and the third through hole (8).

6. The carrier for reflow soldering of flat power modules of claim 2, wherein: There are at least two groups of pin shaft positioning columns, one group has two, which are respectively arranged at the four corners of the middle part of the reflow base, so as to ensure the positioning effect of the metal substrate (3) and the DBC fixing frame (4).

7. The carrier for reflow soldering of flat power modules of claim 1, wherein: The reflow base (1) is an aluminum flat plate.

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