A kind of intelligent power module and its preparation method

Abstract

The present invention relates to the technical field of electronic devices, and discloses an intelligent power module and a preparation method thereof, wherein the intelligent power module comprises a substrate, a chip and a plurality of conductive pins are arranged on the substrate, one end of the conductive pin is connected to the chip, and the end of the other end forms a welding foot; an external pin frame, the external pin frame comprises a plurality of leads corresponding to the plurality of welding feet one by one, and the end of one end of the lead forms a connection structure; in each group of mutually corresponding connection structures and welding feet, the connection structure comprises: a connection part, and a support part located on both sides of the connection part and extending toward the substrate, the arrangement direction of the support part is the same as the arrangement direction of the welding foot, and a accommodating space is formed between the two support parts, and the welding foot is located between the two support parts. In the intelligent power module, the support part isolates two adjacent welding feet, and during reflow soldering, reduces the risk of short circuit caused by the connection of the bonding materials on the adjacent welding feet; the support part plays a limiting role, and reduces the risk of dislocation of the welding point.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic devices, and in particular to an intelligent power module and a preparation method thereof. Background Art

[0002] Intelligent power module (IPM) not only integrates power switch devices and drive circuits, but also has built-in fault detection circuits such as overvoltage, overcurrent and overheating. It is easy to use, not only reduces the size of the system, but also enhances the reliability of the system, winning an increasingly large market. It is especially suitable for frequency converters and various inverter power supplies for driving motors. It is an ideal power electronic device for variable frequency speed regulation, metallurgical machinery, electric traction, servo drive, and variable frequency home appliances.

[0003] In intelligent power modules, in order to improve the heat dissipation capacity of the module, it will be a trend to use DBC ceramic substrates as chip carriers; the chip is welded on the substrate, and a plurality of pins electrically connected to the chip are provided on the substrate. The pins can be electrically connected to other components through the intermediate frame to achieve electrical connection between the chip and other components. However, due to the high pin density on the substrate and the limited bonding area, the bonding structure reliability of the intermediate frame and the pins on the substrate is poor, and it is also easy to cause the adjacent pins to be connected, resulting in short circuits and other risks. Therefore, how to solve the reliable bonding of the pins on the intermediate frame and the substrate is a problem that needs to be solved urgently. Summary of the invention

[0004] The present invention discloses an intelligent power module and a preparation method thereof. In the above-mentioned intelligent power module, the support part of the connection structure of the external pin frame can isolate two adjacent welding feet, which reduces the risk of bonding material splashing to both sides during reflow soldering, and can prevent the bonding material from flowing to adjacent welding feet, effectively reducing the risk of short circuit caused by the bonding materials on adjacent welding feet being connected; the welding feet are covered in the connection structure, and the support parts on both sides can play a certain limiting role, which can effectively avoid the risk of welding point misalignment during preparation and effectively ensure the connection accuracy between the lead and the welding foot.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] An intelligent power module, comprising:

[0007] A substrate, on which a chip and a plurality of conductive pins spaced apart along the periphery of the chip are disposed, one end of each conductive pin being connected to the chip and the other end forming a welding foot;

[0008] An external lead frame, the external lead frame comprising a plurality of leads corresponding to the plurality of welding pins one by one, the end of one end of each lead being formed with a connection structure for connecting to the corresponding welding pin; in each set of mutually corresponding connection structures and welding pins, the connection structure comprises: a connection portion arranged corresponding to the top surface of the welding pin, and support portions located at both sides of the connection portion and extending toward the substrate, the arrangement direction of the support portions is the same as the arrangement direction of the welding pins, a receiving space is formed between two of the support portions, and the welding pin is located between the two support portions;

[0009] A bonding material is provided on the top surface of the welding leg and is located between the welding leg and the connecting portion, and the welding leg and the connecting portion are connected through the bonding material.

[0010] The above-mentioned intelligent power module includes a substrate, a chip is welded on the substrate, and a plurality of conductive pins are arranged on the substrate. The conductive pins are arranged and distributed in sequence around the outer peripheral side of the chip. There is a gap between adjacent conductive pins and they are insulated from each other. One end of each conductive pin is connected to the electrode metal of the chip to achieve electrical connection between each conductive pin and the chip. The end of the other end of each conductive pin forms a welding foot. Then, the plurality of welding feet will be distributed in sequence around the chip and arranged in intervals along the circumference of the chip. Specifically, the plurality of welding feet on the same side of the chip peripheral side can be neatly arranged in sequence and have an arrangement direction. The external lead frame includes a plurality of leads, which are conductive leads. The plurality of leads are connected to the substrate. The plurality of welding feet on the substrate are connected one by one. Specifically, in the corresponding leads and welding feet, the end of one end of each lead forms a connection structure connected to the welding foot. Specifically, in each group of corresponding connection structures and welding feet, the connection structure includes a connection portion opposite to the top surface of the welding foot away from the substrate, and support portions extending toward the substrate are provided on both sides of the connection portion. An accommodating space is formed between the two support portions on both sides of the connection portion. The welding foot can be located in the accommodating space of the two support portions. The top surface of the welding foot is opposite to the connection portion, wherein the arrangement direction of the two support portions is the same as the arrangement direction of the welding foot. That is, in the connection structure, two side edges of the connection portion extend toward the substrate to form two The supporting part, the two supporting parts and the connecting part form a groove structure, and the cross-section of the groove structure is an inverted "U" shape, wherein the two supporting parts respectively form two side walls, and the connecting part forms the bottom wall of the groove structure. For the cooperation between the connecting structure and the welding foot, it is equivalent to the connecting structure covering the welding foot, the connecting part is opposite to the top surface of the welding foot, and the two supporting parts are respectively located on the opposite sides of the welding foot. Since there are multiple welding feet and there are corresponding multiple leads, the multiple welding feet are respectively assembled and connected with the multiple connecting structures in a one-to-one manner. Then, along the arrangement direction of the welding feet, the connecting structure covers the welding feet, and the supporting part of the connecting structure will be between two adjacent welding feet, so that the two adjacent welding feet can be isolated, and the connecting structure The structure covers the bonding material on the top surface of the connecting foot. When reflow soldering is performed, the bonding material can be effectively prevented from splashing to both sides, reducing the risk of the bonding material splashing to both sides, and can prevent the bonding material from flowing to adjacent welding feet. When there is too much bonding material, the bonding materials on adjacent welding feet can be prevented from being connected, effectively reducing the risk of short circuit caused by the connection of bonding materials on adjacent welding feet; the welding foot is covered in the connection structure, and the supporting parts on both sides can play a certain limiting role. During the preparation process, when the external lead frame is assembled with the substrate but not yet fixed, the connection structure of the lead and the welding foot limit are stable, which can effectively reduce the risk of welding point dislocation caused by factors such as vibration during preparation, and effectively ensure the connection accuracy between the lead and the welding foot.

[0011] Therefore, in the above-mentioned intelligent power module, the supporting part of the connection structure of the external pin frame can isolate two adjacent welding feet, which reduces the risk of the bonding material splashing to both sides during reflow soldering, and can prevent the bonding material from flowing to adjacent welding feet, effectively reducing the risk of short circuit caused by the bonding materials on adjacent welding feet being connected; the welding feet are covered in the connection structure, and the supporting parts on both sides can play a certain limiting role, which can effectively reduce the risk of dislocation of the welding points during preparation, and effectively ensure the connection accuracy between the leads and the welding feet.

[0012] Optionally, along a direction perpendicular to the substrate, the two support portions of each connecting structure have the same size.

[0013] Optionally, in each of the connection structures, one end of the support portion of the connection structure facing the substrate is in contact with and connected to the substrate.

[0014] Optionally, a boss structure is provided on a side of the connecting portion facing the welding foot.

[0015] Optionally, the connecting portion and the two supporting portions are an integrated structure.

[0016] Optionally, the substrate is a ceramic substrate.

[0017] Optionally, the intelligent power module further includes a PCB circuit board, and the other end of each lead of the external lead frame is electrically connected to the PCB circuit board.

[0018] Optionally, the bonding material includes solder paste, silver paste or sintered silver.

[0019] Optionally, the material of the conductive pin includes copper or aluminum.

[0020] The present invention also provides a method for preparing any one of the intelligent power modules provided by the above technical solutions, comprising:

[0021] Disposing a bonding material on the top surface of each welding leg of the substrate;

[0022] Assembling the external lead frame and the substrate through a carrier, wherein the connection structure of the lead of the external lead frame corresponds to the welding foot one by one, in each set of corresponding connection structures and welding feet, the connection part of the connection structure corresponds to the top surface of the welding foot, the bonding material is located between the connection part and the welding foot, the two support parts of the connection structure are respectively located on both sides of the welding foot, and the arrangement direction of the two support parts is the same as the arrangement direction of the welding foot;

[0023] The bonding material is reflowed to weld the connecting portion to the welding foot. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a partial structure of a substrate and an external lead frame connected to and matched with an intelligent power module provided by an embodiment of the present invention;

[0025] Figure 2 A schematic top view of a connection structure and a welding foot provided in an embodiment of the present invention;

[0026] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure along the AA direction;

[0027] Figure 4 for Figure 2 Schematic diagram of the cross-sectional structure along the BB direction;

[0028] Icon: 1-substrate; 2-chip; 3-external lead frame; 4-binding material; 11-conductive pin; 31-lead; 32-connection structure; 111-soldering foot; 321-connecting part; 322-supporting part; 3211-boss structure. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the present invention provides an intelligent power module, comprising: a substrate 1, on which a chip 2 is provided, and a plurality of conductive pins 11 are spaced apart along the circumference of the chip 2, one end of each conductive pin 11 is connected to the chip 2, and the end of the other end forms a welding foot 111; an external pin frame 3, the external pin frame 3 comprises a plurality of leads 31 corresponding to the plurality of welding feet 111, and the end of one end of each lead 31 is formed with a connection structure 32 for connecting to the corresponding welding foot 111; in each group of mutually corresponding connection structures 32 and welding feet 111, the connection structure 32 comprises: a connection portion 321 provided corresponding to the top surface of the welding foot 111, and support portions 322 located on both sides of the connection portions 321 and extending toward the substrate 1, the arrangement direction of the support portions 322 is the same as the arrangement direction of the welding feet 111, and a receiving space is formed between the two support portions 322, and the welding foot 111 is located between the two support portions 322.

[0031] The above-mentioned intelligent power module includes a substrate 1, on which a chip 2 is welded. Specifically, the chip can be a full-bridge driver chip, wherein the substrate serves as a carrier of the chip, and the chip is connected to the substrate. Specifically, a plurality of conductive pins 11 are arranged on the substrate 1. Specifically, the conductive pins can be metal-clad pins, which are arranged and distributed in sequence around the outer peripheral side of the chip 2. Adjacent conductive pins are spaced and insulated from each other. One end of each conductive pin is connected to the electrode metal of the chip 2 to achieve electrical connection between each conductive pin and the chip 2. The end of the other end of each conductive pin forms a welding foot 111, and the plurality of welding feet 111 will be distributed in sequence around the chip 2 and arranged in intervals along the circumference of the chip 2. Specifically, a plurality of welding feet on the same side of the peripheral side of the chip 2 can be neatly arranged in sequence and have an arrangement direction; the external pin frame 3 includes A plurality of leads 31 are connected to a plurality of welding feet 111 on the substrate 1 in a one-to-one correspondence. Specifically, in the corresponding leads 31 and welding feet 111, the end of one end of each lead 31 forms a connection structure 32 connected to the welding foot 111. Specifically, in each group of corresponding connection structures 32 and welding feet 111, the connection structure 32 includes a connection portion 321 opposite to the top surface of the welding foot 111 away from the substrate 1, and support portions 322 extending toward the substrate 1 are provided on both sides of the connection portion 321. An accommodating space is formed between two support portions 321 on both sides of the connection portion 321. The welding foot 111 can be located in the accommodating space of the two support portions 321. The top surface of the welding foot 111 is opposite to the connection portion 321, wherein the arrangement direction of the two support portions 321 is the same as the arrangement direction of the welding foot 111. That is, in the connection structure, refer to Figure 1 ,like Figure 2 and Figure 3As shown, two side edges of the connecting portion 321 extend toward the direction of the substrate 1 to form two supporting portions 322, and the two supporting portions 322 and the connecting portion 321 form a groove structure, and the cross-section of the groove structure is an inverted "U" shape, wherein the two supporting portions 322 respectively form two side walls, and the connecting portion 321 forms the bottom wall of the groove structure. For the cooperation between the connecting structure 32 and the welding foot 111, it is equivalent to the connecting structure 32 covering the welding foot 111, and the connecting portion 321 is opposite to the top surface of the welding foot 111, and the two supporting portions 322 are respectively located on the opposite sides of the welding foot 111; since there are multiple welding feet 111 and there are corresponding multiple leads 31, after the multiple welding feet 111 are respectively assembled and connected with the multiple connecting structures 32 in a one-to-one manner, along the arrangement direction of the welding feet 111, the connecting structure 32 covers the welding feet 111, and the supporting portions 322 of the connecting structure 32 will be at two adjacent welding feet. The two adjacent welding feet 111 can be isolated between the feet 111, and the connecting structure 32 covers the binding material 4 on the top surface of the connecting foot. When reflow soldering is performed, the binding material 4 can be effectively prevented from splashing to both sides, reducing the risk of the binding material 4 splashing to both sides, and can prevent the binding material 4 from flowing to adjacent welding feet 111. When there is too much binding material 4, the binding material 4 on adjacent welding feet 111 can be prevented from being connected, effectively reducing the risk of short circuit caused by the connection of the binding materials 4 on adjacent welding feet 111; the welding foot 111 is covered in the connecting structure 32, and the supporting parts 322 on both sides can play a certain limiting role. During the preparation process, when the external pin frame 3 and the substrate 1 are assembled but not fixed, the connection structure 32 of the lead 31 and the welding foot 111 are stably limited, which can effectively reduce the risk of welding point misalignment caused by factors such as vibration during preparation, and effectively ensure the connection accuracy between the lead 31 and the welding foot 111.

[0032] Therefore, in the above-mentioned intelligent power module, the support portion 322 of the connection structure 32 of the external pin frame 3 can isolate two adjacent welding feet 111, and during reflow soldering, the risk of the bonding material 4 splashing to both sides is reduced, and the bonding material 4 can be prevented from flowing to adjacent welding feet 111, effectively reducing the risk of short circuit caused by the bonding materials 4 on adjacent welding feet 111 being connected; the welding feet 111 are covered in the connection structure 32, and the support portions 322 on both sides can play a certain limiting role, which can effectively avoid the risk of misalignment of the welding points during preparation, and effectively ensure the connection accuracy between the lead 31 and the welding foot 111.

[0033] Specifically, in the above-mentioned intelligent power module, along the direction perpendicular to the substrate 1, the two supporting portions 322 of each connection structure 32 have the same size; and the supporting portion 322 of the connection structure 32 is in contact with the substrate 1 at one end facing the substrate 1. The two supporting portions 322 support the connection portion 321, which can ensure that the connection portion 321 and the substrate 1 are parallel to each other when the external lead frame is assembled with the substrate 1, thereby reducing the risk of glue overflow on the heat dissipation surface of the product after plastic packaging.

[0034] Specifically, Figure 3 and Figure 4 As shown, in the above intelligent power module, a boss structure 3211 is provided on one side of the connection portion 321 facing the welding foot 111. This can prevent the support portion 322 from causing a gap between the connection portion 321 and the welding foot 111 to accommodate the bonding material 4, and prevent poor bonding in the middle when the bonding material 4 is insufficient, thereby improving the bonding reliability of the welding point between the welding foot 111 and the connection portion 321.

[0035] Specifically, in the above intelligent power module, the connection part 321 and the two supporting parts 322 in each connection structure 32 are an integrated structure. The connection part 321 and the two supporting parts 322 have an integrated structure with good structural properties and strong stability.

[0036] Specifically, in the above-mentioned intelligent power module, the substrate 1 is set as a ceramic substrate, wherein the ceramic substrate is a copper-clad ceramic substrate, which can be a single-sided copper-clad ceramic substrate or a double-sided copper-clad ceramic substrate. The ceramic substrate has high thermal conductivity, high electrical insulation, low expansion, high conductivity and excellent weldability. The ceramic substrate serves as a carrier of the chip 2. Due to its low thermal resistance and good heat dissipation, it saves complicated heat dissipation structure and makes the overall structure simpler.

[0037] Specifically, in the above-mentioned intelligent power module, the intelligent power module also includes a PCB circuit board, and the other end of each lead 31 of the external lead frame 3 is electrically connected to the PCB circuit board. The substrate 1 chip 2 is assembled with the PCB board through the external lead frame 3, and the combination is firm.

[0038] Specifically, in the above-mentioned intelligent power module, the bonding material 4 includes solder paste, silver paste or sintered silver.

[0039] Specifically, in the above-mentioned intelligent power module, the material of the conductive pins includes copper, or other wire materials, which is not limited in this embodiment.

[0040] refer to Figures 1 to 4 As shown, the present invention also provides a method for preparing any one of the intelligent power modules provided in the above embodiments, comprising:

[0041] First, a bonding material 4 is disposed on the top surface of each welding foot 111 of the substrate 1; specifically, the bonding material 4 may be solder paste, silver paste or sintered silver, and may be disposed on the top surface of the welding foot 111 by printing at room temperature;

[0042] Then, the external lead frame is assembled with the substrate 1 by a carrier, wherein the connection structure 32 of the lead 31 of the external lead frame 3 corresponds to the welding foot 111 one by one, and in each set of corresponding connection structures and welding feet, the connection portion 321 of the connection structure 32 corresponds to the top surface of the welding foot 111, the bonding material 4 is located between the connection portion 321 and the welding foot 111, and the two support portions 322 of the connection structure 32 are respectively located on both sides of the welding foot 111, and the arrangement direction of the two support portions is the same as the arrangement direction of the welding foot;

[0043] Finally, the bonding material 4 is reflowed to weld the connection portion 321 to the welding foot 111 .

[0044] Among them, the bonding material 4 is reflowed, specifically, after the external pin frame and the substrate 1 are assembled, the bonding material 4 is subjected to high-temperature treatment, and the bonding material 4 forms a liquid at high temperature, thereby connecting with the connecting part 321 and the welding foot 111, and then cooled down to make the bonding material 4 solid, and then the connecting part 321 and the welding foot 111 are welded.

[0045] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An intelligent power module, characterized in that: include: A substrate, on which a chip and a plurality of conductive pins spaced apart along the periphery of the chip are arranged, one end of each conductive pin being connected to the chip and the other end forming a welding foot; An external lead frame, the external lead frame includes a plurality of leads corresponding to the welding feet one by one, and a connection structure for connecting to the corresponding welding foot is formed at the end of one end of each lead; in each group of mutually corresponding connection structures and welding feet, the connection structure includes: a connection portion arranged corresponding to the top surface of the welding foot, and support portions located on both sides of the connection portion and extending toward the substrate, the arrangement direction of the support portions is the same as the arrangement direction of the welding feet, a receiving space is formed between two of the support portions, and the welding foot is located between the two support portions; A bonding material is provided on the top surface of the welding leg and is located between the welding leg and the connecting portion, and the welding leg and the connecting portion are connected through the bonding material.

2. The intelligent power module according to claim 1, characterized in that: Along a direction perpendicular to the substrate, the two support portions of each connecting structure have the same size.

3. The intelligent power module according to claim 1 or 2, characterized in that: In each of the connection structures, one end of the support portion of the connection structure facing the substrate is in contact with and connected to the substrate.

4. The intelligent power module according to claim 1, characterized in that: A boss structure is arranged on one side of the connection portion facing the welding foot.

5. The intelligent power module according to claim 1, characterized in that: The connecting portion and the two supporting portions are an integrated structure.

6. The intelligent power module according to claim 1, characterized in that: The substrate is a ceramic substrate.

7. The intelligent power module according to claim 1, characterized in that: It also includes a PCB circuit board, and the other end of each lead of the external lead frame is electrically connected to the PCB circuit board.

8. The intelligent power module according to claim 1, characterized in that: The bonding material includes solder paste, silver paste or sintered silver.

9. The intelligent power module according to claim 1, characterized in that: The conductive pins are made of copper or aluminum.

10. A method for preparing an intelligent power module according to any one of claims 1 to 9, characterized in that: include: Disposing a bonding material on the top surface of each welding leg of the substrate; Assembling the external lead frame and the substrate through a carrier, wherein the connection structure of the lead of the external lead frame corresponds to the welding foot one by one, in each set of corresponding connection structures and welding feet, the connection part of the connection structure corresponds to the top surface of the welding foot, the bonding material is located between the connection part and the welding foot, the two support parts of the connection structure are respectively located on both sides of the welding foot, and the arrangement direction of the two support parts is the same as the arrangement direction of the welding foot; The bonding material is reflowed to weld the connecting portion to the welding foot.

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