阅读说明：本技术 一种改善SiC功率器件封装热均匀性的封装结构 (Packaging structure for improving packaging thermal uniformity of SiC power device ) 是由 何少伟 马敏辉 宋召海 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种改善SiC功率器件封装热均匀性的封装结构,包括SiC芯片一、SiC芯片二、DBC上铜层一、DBC上铜层二、DBC上铜层三、DBC陶瓷层、DBC下铜层以及基板；所述DBC上铜层一、DBC上铜层二、DBC上铜层三以及所述DBC下铜层的表面均刻蚀镂空结构焊料层；所述SiC芯片一的上表面通过键合铝包铜带与所述DBC上铜层二上的所述镂空结构焊料层相连；所述SiC芯片二的上表面通过键合铝包铜带与所述DBC上铜层三上的所述镂空结构焊料层相连。本申请的封装结构散热均匀、可靠性高,键合铝包铜带导电性能好、寄生电感小,可以有效加固键合线的连接,提高SiC功率器件的使用寿命。(The invention discloses a packaging structure for improving the packaging thermal uniformity of a SiC power device, which comprises a SiC chip I, a SiC chip II, a DBC upper copper layer I, a DBC upper copper layer II, a DBC upper copper layer III, a DBC ceramic layer, a DBC lower copper layer and a substrate; etching hollow structure solder layers on the surfaces of the DBC upper copper layer I, the DBC upper copper layer II, the DBC upper copper layer III and the DBC lower copper layer; the upper surface of the SiC chip I is connected with the hollow structure solder layer on the DBC upper copper layer II through a bonded aluminum-clad copper strip; and the upper surface of the SiC chip II is connected with the hollow structure solder layer on the DBC upper copper layer III through a bonded aluminum-clad copper strip. The packaging structure has the advantages of uniform heat dissipation, high reliability, good conductivity of the bonded aluminum-clad copper strip, small parasitic inductance, effective reinforcement of connection of bonding wires and improvement of service life of SiC power devices.)

1. A packaging structure for improving packaging thermal uniformity of a SiC power device comprises a first SiC chip, a second SiC chip, a first DBC upper copper layer, a second DBC upper copper layer, a third DBC upper copper layer, a DBC ceramic layer, a lower DBC copper layer and a substrate; the method is characterized in that hollow-structure solder layers are etched on the surfaces of the DBC upper copper layer I, the DBC upper copper layer II, the DBC upper copper layer III and the DBC lower copper layer;

the upper surface of the SiC chip I is connected with the hollow structure solder layer on the DBC upper copper layer II through a bonded aluminum-clad copper strip; the upper surface of the SiC chip II is connected with the hollow-out structure solder layer on the DBC upper copper layer III through a bonded aluminum-clad copper strip; the lower surface of the first SiC chip is welded on the first copper layer on the DBC through a hollow structure solder layer, the lower surface of the second SiC chip is welded on the second copper layer on the DBC through a hollow structure solder layer, and the lower copper layer of the DBC is welded on the substrate through a hollow structure solder layer.

2. The package structure for improving the thermal uniformity of the package of the SiC power device as claimed in claim 1, wherein the dimensions of the rectangular periphery of the etched-out structure of the first copper layer on the DBC are the same as the dimensions of the periphery of the first SiC chip, the dimensions of the rectangular periphery of the etched-out structure of the second copper layer on the DBC are the same as the overall dimensions of the periphery of the bonding surface of the second bonded aluminum-clad copper tape on the SiC chip, and the dimensions of the rectangular periphery of the etched-out structure of the third copper layer on the DBC are the same as the dimensions of the bonding surface of the bonding aluminum-clad copper tape.

3. The packaging structure for improving the thermal uniformity of the SiC power device package according to claim 1, wherein the hollow structure solder layer is integrally etched into a rectangular deep groove, and the inner wall of the deep groove is perpendicular to the surface of the etched body; and a plurality of copper columns with equal distance and equal height are reserved in the deep groove.

4. The structure for improving the thermal uniformity of the SiC power device package of claim 3, wherein the copper pillar is a cylinder, a regular quadrangular prism or a linear straight quadrangular prism with a rectangular top surface longer than the width.

Technical Field

The invention relates to the technical field of heat dissipation and packaging of power electronic devices, in particular to a packaging structure for improving the packaging heat uniformity of a SiC power device.

Background

SiC is a novel wide bandgap semiconductor material which is developed very well at present, and can be used for manufacturing high-power electronic devices, such as SiC MOSFET, SiC JFET, SiC IGBT and the like. Compared with a Si power device, the SiC power device has the advantages of low on-resistance, high switching frequency, high temperature and high pressure resistance and the like, and has great application prospect and industrial value in the high-frequency and high-pressure field. The copper-clad ceramic substrate DBC is directly bonded with copper layers on the upper surface and the lower surface of a ceramic layer, and the excellent performances of ceramic and oxygen-free copper are perfectly combined. Copper wire and aluminium wire are the bonding wire of commonly used, and aluminium wire associativity is good but the current-carrying capacity is low, and copper wire electric conduction heat-conducting property is superior to aluminium wire but need to be to metal surface pretreatment, and the technology is more complicated. As a novel bonding wire, the aluminum-clad copper strip has the dual advantages of aluminum and copper, and is superior in banded current-carrying capacity and heat dissipation effect compared with a linear bonding wire.

The traditional SiC power device packaging technology is that the lower surface of a SiC chip is welded at the upper copper layer of a DBC, the upper surface of the SiC chip is connected with other independent upper copper layers by using a bonding aluminum wire, the lower copper layer of the DBC is welded on a substrate, the substrate is directly connected with a shell for heat dissipation, and different layers are connected through a solder layer.

Firstly, under the repeated impact of thermal stress generated by the chip working, bonding points are easy to age to cause the bonded aluminum wire to fall off, and the reliability of the device is poor; secondly, cavities and cracks exist in a welding flux layer between the chip and a copper layer on the DBC, and uniform tiling is difficult to achieve, so that the heat dissipation of the lower surface of the SiC chip is uneven, and the SiC power device is prone to failure due to overhigh junction temperature; and thirdly, the solder layer between the lower copper layer and the substrate is uneven, and the whole device is easy to incline.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

The invention aims to provide a packaging structure for improving the packaging thermal uniformity of a SiC power device, so as to solve the problems in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a packaging structure for improving the packaging thermal uniformity of a SiC power device, which comprises a first SiC chip, a second SiC chip, a first DBC upper copper layer, a second DBC upper copper layer, a third DBC upper copper layer, a DBC ceramic layer, a lower DBC copper layer and a substrate, wherein the first DBC upper copper layer is a first metal layer; etching hollow structure solder layers on the surfaces of the DBC upper copper layer I, the DBC upper copper layer II, the DBC upper copper layer III and the DBC lower copper layer;

the upper surface of the SiC chip I is connected with the hollow structure solder layer on the DBC upper copper layer II through a bonded aluminum-clad copper strip; the upper surface of the SiC chip II is connected with the hollow-out structure solder layer on the DBC upper copper layer III through a bonded aluminum-clad copper strip; the lower surface of the first SiC chip is welded on the first copper layer on the DBC through a hollow structure solder layer, the lower surface of the second SiC chip is welded on the second copper layer on the DBC through a hollow structure solder layer, and the lower copper layer of the DBC is welded on the substrate through a hollow structure solder layer.

As a further technical solution, the dimension of the rectangular periphery of the etched and hollowed structure of the first copper layer on the DBC is the same as the dimension of the periphery of the first SiC chip, the dimension of the rectangular periphery of the etched and hollowed structure of the second copper layer on the DBC is the same as the total peripheral dimension of the profile of the bonding surface of the second bonding aluminum clad copper tape on the SiC chip, and the dimension of the rectangular periphery of the etched and hollowed structure of the third copper layer on the DBC is the same as the profile of the bonding surface of the bonding aluminum clad copper tape.

As a further technical scheme, the hollow-out structure solder layer is integrally etched into a rectangular deep groove, and the inner wall of the deep groove is vertical to the surface of the etched body; and a plurality of copper columns with equal distance and equal height are reserved in the deep groove.

As a further technical scheme, the copper column is a cylinder, a regular quadrangular prism or a linear straight quadrangular prism with the top surface rectangular longer than the width.

By adopting the technical scheme, the invention has the following beneficial effects:

the improved packaging structure has the advantages of uniform heat dissipation, high reliability, good conductivity of the bonded aluminum-clad copper strip and small parasitic inductance, and can effectively reinforce the connection of bonding wires and prolong the service life of SiC power devices. And, newly establish hollow structure solder layer, pack into in the hollow rectangular channel with the solder for standby, the copper post that remains in the groove is used for supporting the SiC chip, and its top surface is the reference surface, needs to guarantee that the solder horizontal plane of packing does not exceed the reference surface. The hollow-out structure solder layer can reduce the problem of junction temperature of the SiC power device module caused by uneven height of the traditional solder layer, and can improve the condition of integral inclination of the device. And the traditional solder layer is removed, so that the thickness of the device is reduced, and the whole device is more portable.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic diagram of a cross-sectional structure of a conventional SiC power device package.

Fig. 2 is a schematic cross-sectional structure of the present invention.

Fig. 3 is a top view of the package of fig. 2 without the SiC chip soldered and with the copper pillar remaining in the hollow groove as a cylinder.

Fig. 4 is a top view of the package of fig. 2 without the SiC chip bonded and with the copper pillars remaining in the hollowed-out grooves being of a regular quadrangular prism type.

Fig. 5 is a top view of the straight quadrangular prism package of fig. 2 without the SiC chip soldered and with the copper pillars remaining in the hollow grooves as lines.

The symbols in the figure are as follows: 1: bonding an aluminum wire; a first SiC chip; 2b, a second SiC chip; 3. a conventional solder layer; copper layer one on DBC; copper layer two on DBC; copper layer three on DBC; a DBC ceramic layer; a lower copper layer of DBC; 7. a substrate; 8. bonding the aluminum-clad copper strip; 9. and a hollow structure solder layer.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

As shown in fig. 1, a bonded aluminum wire 1 is selected for packaging a conventional SiC power device, the bonded aluminum wire 1 has a relatively high resistivity, poor fixing reliability and a poor heat dissipation effect, a conventional solder layer 3 cannot ensure uniform height, junction temperature problems of a first SiC chip 2a and a second SiC chip 2b can be caused subsequently, and the conventional solder layer 3 is uneven, which eventually causes the inclination of the whole device.

As shown in fig. 2, the present invention provides a package structure for improving thermal uniformity of a SiC power device package, including a SiC chip one 2a, a SiC chip two 2b, a DBC upper copper layer one 4a, a DBC upper copper layer two 4b, a DBC upper copper layer three 4c, a DBC ceramic layer 5, a DBC lower copper layer 6, and a substrate 7; etching a hollow structure solder layer 9 on the surfaces of the first DBC upper copper layer 4a, the second DBC upper copper layer 4b, the third DBC upper copper layer 4c and the lower DBC copper layer 6;

the upper surface of the SiC chip I2 a is connected with the hollowed-out structure solder layer on the DBC upper copper layer II 4b through a bonding aluminum-clad copper strip 8; the upper surface of the SiC chip II 2b is connected with the hollow structure solder layer on the DBC upper copper layer III 4c through a bonded aluminum-clad copper strip 8; the lower surface of the SiC chip I2 a is welded on the DBC upper copper layer I4 a through a hollow structure solder layer, the lower surface of the SiC chip II 2b is welded on the DBC upper copper layer II 4b through a hollow structure solder layer, and the DBC lower copper layer 6 is welded on the substrate 7 through a hollow structure solder layer.

In this embodiment, as a further technical solution, a dimension of a rectangular periphery of an etched-out structure of the first copper layer 4a on the DBC is the same as a dimension of a periphery of the first SiC chip 2a, a dimension of a rectangular periphery of an etched-out structure of the second copper layer 4b on the DBC is the same as a total peripheral dimension of a profile of a bonding surface of the second SiC chip 2b plus the bonding aluminum-clad copper tape, and a dimension of a rectangular periphery of an etched-out structure of the third copper layer 4c on the DBC is the same as a profile of the bonding aluminum-clad copper tape.

In the embodiment, as a further technical scheme, the hollow-out structure solder layer is integrally etched into a rectangular deep groove, and the inner wall of the deep groove is vertical to the surface of the etched body; and a plurality of copper columns with equal distance and equal height are reserved in the deep groove.

In this embodiment, as a further technical solution, the copper pillar is a cylinder (shown in structure fig. 3), a regular quadrangular prism (shown in structure fig. 4), or a linear straight quadrangular prism (shown in structure fig. 5) with a top surface rectangular longer than a width.

The copper pillar structure is taken as a conical structure with a round top as an example for further scheme introduction. Cylinders in the hollow structure solder layers 9 of the first DBC upper copper layer 4a, the second DBC upper copper layer 4b, the third DBC upper copper layer 4c and the lower DBC copper layer 6 are equidistant, equal in inner diameter and equal in height, and a proper amount of solder with a proper thermal expansion coefficient is filled in the groove. The whole horizontal plane of the solder filled in each groove is controlled not to exceed the top surface of the cylindrical copper column, and the top surface of the cylindrical copper column is used as a reference surface. Under the same working temperature, the solder level filled in each groove is the same, and the flatness of the device is further ensured. The values of the distance, the height and the like of the cylindrical copper columns can be flexibly adjusted by changing the concentration of an etching agent, the etching time and the like according to the actual sizes of the SiC chip I2 a, the SiC chip II 2b, the DBC upper copper layer I4 a, the DBC upper copper layer II 4b, the DBC upper copper layer III 4c and the DBC lower copper layer 6.

In summary, the application relates to a packaging structure for improving the packaging thermal uniformity of a SiC power device, an aluminum-clad copper strip is selected as a bonding wire, the bonding property of an aluminum outer layer and the surface of a chip is good, the electric conduction and heat conduction capability of a copper inner core is strong, the surface area of the strip is large, heat dissipation is easy, and the high-temperature working performance of a module can be improved; the improved solder layer is a novel structure that a plurality of copper columns are still reserved in the integral rectangular deep groove, the groove is filled with solder with proper thermal expansion coefficient for standby, and the novel solder layer can reduce the integral thickness of the package, so that the device is light; meanwhile, the hollow-out structure solder layer can avoid the junction temperature problem caused by the unevenness of the traditional solder layer, and the service life of the SiC power device is prolonged.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.