Bonding structure and power module

Abstract

The utility model provides a bonding structure and a power module, the bonding structure comprises a chip and a bonding sheet, the chip is provided with a sintering area, one side of the bonding sheet close to the chip is provided with a boss part, and the boss part protrudes out of the bonding sheet along a direction towards the sintering area; the boss part is provided with a bonding surface, the bonding surface corresponds to one side surface, close to the chip, of the boss part, and the projection of the bonding surface on the chip is located in the sintering area; a hot-pressing action area is arranged on one side, far away from the chip, of the bonding sheet, the projection of the bonding surface on the bonding sheet is located in the hot-pressing action area, and the bonding sheet and the chip are sintered and welded through the hot-pressing action applied to the hot-pressing action area. The bonding sheet and the chip are sintered and welded in a hot pressing mode, and the structural design of the bonding sheet is matched, so that the sintering quality of the chip and the bonding sheet is ensured, the chip is prevented from being damaged during hot pressing sintering, meanwhile, various tolerance conflict problems can be solved, and the product yield is improved. The power module adopts the bonding structure, so that the product quality and reliability are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power module manufacturing in the semiconductor industry, in particular to a bonding structure and a power module. Background Art

[0002] In the semiconductor industry, due to the high power and large current carrying capacity of power modules, multiple bonding wires need to be bonded on the chip. However, the wire diameter of the bonding wire is small, and it is easy to crack and break due to current shock and thermal shock during use. Therefore, many power modules currently use sheet-shaped widened bonding sheets to replace bonding wires to improve the current carrying capacity and reliability of power modules. The bonding sheets are generally fixed on the chip by welding or pressure sintering after positioning and installation. In the pressure sintering process of the bonding sheet and the chip, due to considerations of dimensional accuracy and positioning accuracy, when the pressure head is pressed down for sintering, there is a place in the sintering area of ​​the bonding sheet that is not pressed by the pressure head, which affects the sintering quality; however, if the area of ​​the bonding sheet is increased, it may touch the parts outside the sintering area of ​​the chip during pressure sintering, causing damage to the chip, so improvements are needed. Utility Model Content

[0003] One purpose of the utility model is to solve the shortcomings of the prior art and propose a bonding structure that is convenient for improving the sintering welding quality, avoiding damage to the chip during hot pressing sintering, and improving the product yield.

[0004] The second purpose of the utility model is to solve the shortcomings of the prior art and propose a power module to improve product quality and reliability.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] According to a first aspect of the utility model, a bonding structure is provided, which includes a chip and a bonding sheet, wherein the bonding sheet and the chip are sintered and welded by hot pressing, a sintering zone is provided on the chip, and the bonding sheet is provided above the chip; a boss portion is provided on a side of the bonding sheet close to the chip, and the boss portion protrudes from the bonding sheet along a direction toward the sintering zone; the boss portion has a bonding surface, and the bonding surface corresponds to a side of the boss portion close to the sintering zone, and the projection of the bonding surface on the chip is within the sintering zone; a hot pressing action zone is provided on a side of the bonding sheet away from the chip, and the projection of the bonding surface on the bonding sheet is within the hot pressing action zone, and the bonding surface and the sintering zone are sintered and welded by hot pressing in the hot pressing action zone.

[0007] Preferably, the bonding sheet comprises a first sheet body, a second sheet body and a bending portion, and the first sheet body and the second sheet body are connected via the bending portion; the boss portion and the hot pressing action area are respectively arranged on the first sheet body.

[0008] Preferably, a first clearance space is provided between the boss portion and the bending portion, and a second clearance space is provided between the hot pressing action zone and the bending portion.

[0009] Preferably, a side of the boss portion close to the bent portion is connected to the first sheet body in an arc shape.

[0010] Preferably, a metal coating is provided on the bonding surface.

[0011] Preferably, the metal plating layer is gold or silver.

[0012] Preferably, the sintering area is provided with a bonding material, and the bonding material is used to sinter and weld the chip and the bonding sheet under the action of heat and pressure.

[0013] Preferably, the bonding material is silver, and the bonding sheet is a copper sheet.

[0014] Preferably, a sink is provided in the hot pressing action zone.

[0015] According to a second aspect of the present invention, a power module is provided, which includes the above-mentioned bonding structure.

[0016] Compared with the prior art, the beneficial effects of the utility model are:

[0017] 1. In the bonding structure of the utility model, a sintering area is provided on the chip, a boss portion and a hot pressing area are provided on the bonding sheet, and the projection of the bonding surface of the boss portion on the chip is in the sintering area, and the projection of the bonding surface on the bonding sheet is in the hot pressing area. The bonding surface of the bonding sheet and the sintering area of ​​the chip are sintered and welded by hot pressing applied to the hot pressing area. In this way, the sintering and welding quality of the chip and the bonding sheet is guaranteed, and damage to the chip during hot pressing sintering is avoided. At the same time, various tolerance conflict problems can be solved, and the product yield rate is improved;

[0018] 2. The power module of the utility model adopts the above bonding structure, which improves product quality and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a bonding structure of an embodiment of the utility model.

[0020] Figure 2 It is a schematic structural diagram of a bonding structure during hot pressing and sintering of an embodiment of the utility model.

[0021] Figure 3 It is a structural schematic diagram of a bonding structure of another embodiment of the utility model.

[0022] Figure 4 This is a schematic diagram of the structure after the bonding structure of another embodiment of the utility model is disassembled.

[0023] Figure 5 This is a schematic structural diagram of a bonding structure during hot pressing and sintering of another embodiment of the present invention.

[0024] Figure 6 It is a schematic structural diagram of another embodiment of the present invention during hot pressing and sintering of the bonding structure at another viewing angle.

[0025] Figure 7 It is a schematic structural diagram of a bonding sheet in another embodiment of the utility model.

[0026] In the figure, 10-chip, 11-sintering area, 20-bonding sheet, 21-boss part, 211-bonding surface, 22-first sheet body, 23-second sheet body, 24-bending part, 25-first clearance space, 26-hot pressing action area, 27-sinking groove, 30-hot pressing head, 31-second clearance space. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the utility model. It can be understood that some technical means of the various embodiments described herein can be replaced or combined with each other without conflict.

[0028] In the description of the present invention, if there are terms such as "first", "second", etc., they are only used to distinguish the objects described, and do not have any order or technical meaning. Therefore, the objects defined as "first", "second", etc. may explicitly or implicitly include one or more of the objects. Moreover, "one" or "a" and similar words do not indicate a quantity limitation, but indicate the existence of at least one, and "multiple" means not less than two.

[0029] In the description of the utility model specification, reference to "one embodiment" or "some embodiments" etc. means that one or more embodiments of the utility model include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. appearing in different places in the specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0030] See also Figure 1 According to the first aspect of the utility model, a bonding structure is provided, which includes a chip 10 and a bonding sheet 20, and the bonding sheet 20 and the chip 10 are sintered and welded by hot pressing. Specifically, a sintering area 11 is provided on the chip 10, and the bonding sheet 20 is arranged above the chip 10. A boss portion 21 is provided on the side of the bonding sheet 20 close to the chip 10, and the boss portion 21 protrudes from the bonding sheet 20 in the direction toward the sintering area 11. The boss portion 21 has a bonding surface 211, and the bonding surface 211 corresponds to a side of the boss portion 21 close to the sintering area 11, that is, corresponds to Figure 1 The bottom surface of the middle boss portion 21, the bonding surface 211 is attached to the sintering area 11, the area of ​​the bonding surface 211 is not larger than the area of ​​the sintering area 11, and the projection of the bonding surface 211 on the chip 10 is within the sintering area 11, or in other words, the sintering area 11 covers the projection of the bonding surface 211 on the chip 10. A hot pressing action area 26 is provided on the bonding sheet 20 on the side away from the chip 10, the area of ​​the bonding surface 211 is not larger than the area of ​​the hot pressing action area 26, and the projection of the bonding surface 211 on the bonding sheet 20 is within the hot pressing action area 26, or in other words, the hot pressing action area 26 covers the projection of the bonding surface 211 on the bonding sheet 20, and the bonding surface 211 of the bonding sheet 20 and the sintering area 11 of the chip 10 are sintered and welded by the hot pressing action applied to the hot pressing action area 26. It should be understood that in order to ensure the connection strength between the bonding surface 211 and the sintering interface of the sintering zone 11 , the bonding surface 211 is preferably designed to be a plane.

[0031] See also Figure 2In the hot pressing and sintering process of the bonding sheet 20 and the chip 10, the bonding sheet 20 is positioned and installed on the chip 10, the bonding surface 211 is attached to the sintering area 11, the hot pressing head 30 is arranged above the bonding sheet 20, and the hot pressing head 30 acts on the hot pressing action area 26 of the bonding sheet 20, so that heat and pressure can be evenly applied to the boss portion 21, thereby ensuring the sintering and welding quality of the chip 10 and the bonding sheet 20; at the same time, the design of the boss portion 21 forms an air avoidance structure between the chip 10 and the bonding sheet 20 body, thereby avoiding damage to the chip 10 during hot pressing and sintering; in addition, the design of the boss portion 21 can ensure greater redundancy to accommodate the installation tolerance when the bonding sheet 20 is installed in the sintering area 11, thereby reducing the process difficulty, solving various tolerance conflict problems, and improving the product yield.

[0032] Among them, the bonding sheet 20 adopts a wider sheet structure to replace the traditional small-diameter bonding wire, so that the area for conducting current is larger, it can carry a larger current, and play a better role in current conduction; compared with the bonding wire, the bonding sheet 20 has a greater structural strength and can bear a greater stress, thereby improving the reliability of the product. The thermal pressing head 30 can move in a direction perpendicular to the bonding sheet 20. When the thermal pressing head 30 is pressed down, its heat and pressure act evenly on the bonding sheet 20, so that the boss portion 21 is tightly bonded to the sintering area 11 of the chip 10, realizing the sintering welding effect.

[0033] Furthermore, the boss portion 21 can be integrally formed on the bonding sheet 20, for example, by a stamping process, or by removing a portion of the material from the corresponding portion of the bonding sheet 20, or by adding material to the corresponding portion of the bonding sheet 20. It is understandable that the thickness between the bonding surface 211 and the hot pressing action area 26 should be greater than the thickness of the other parts of the bonding sheet 20 body (the part where the boss portion 21 is not provided). The protruding thickness and shape of the boss portion 21 can be reasonably set according to actual conditions, and the utility model does not limit this. For example, the protruding thickness of the boss portion 21 can be designed to be half the thickness of the bonding sheet 20 body or designed to be equivalent to the thickness of the bonding sheet 20 body; the boss portion 21 can be designed as a square column, a trapezoidal platform or other structures. The design of the boss portion 21 forms an air avoidance structure between the main body of the bonding sheet 20 and the chip 10. During the hot pressing and sintering process, only the boss portion 21 is in direct contact with the sintering area 11, which effectively avoids damage to the chip 20 caused by the bonding sheet 20 and improves the product yield. It can also ensure greater redundancy to accommodate the installation tolerance when the bonding sheet 20 is installed in the sintering area 11, thereby reducing the process difficulty and solving various tolerance conflict problems.

[0034] In some embodiments, the sintering area 11 is provided with bonding material, and under the heat pressing action of the hot pressing head 30 , the bonding material sinters and welds the chip 10 and the bonding sheet 20 .

[0035] Furthermore, the bonding material can be silver paste, etc., and the sintering welding of the chip 10 and the bonding sheet 20 can be achieved by silver sintering. The silver sintering process belongs to the prior art and will not be described here. The bonding sheet 20 is made of metal material, such as copper sheet. Compared with the bonding wire, the copper sheet has higher current carrying capacity and structural strength, which can improve the reliability of the product.

[0036] Please refer to Figures 3 to 6 In other embodiments, the bonding sheet 20 is a bent structure, and the bonding sheet 20 includes a first sheet body 22, a second sheet body 23 and a bent portion 24, and the first sheet body 22 and the second sheet body 23 are connected by the bent portion 24; the boss portion 21 and the hot pressing action area 26 are respectively arranged on the first sheet body 22. The sintering area 11 of the chip 10 is sintered and welded with the boss portion 21 of the bonding sheet 20.

[0037] Furthermore, a first clearance space 25 is provided between the boss portion 21 and the bend portion 24; a second clearance space 31 is provided between the hot pressing action area 26 and the bend portion 23. In this way, the hot pressing head 30 can avoid the bend portion 24 during hot pressing sintering to avoid damage to the chip 10. At the same time, the design of the clearance space can ensure greater redundancy to accommodate the installation tolerance when the bonding sheet 20 is installed in the sintering area 11, thereby reducing the process difficulty. Among them, the size of the first clearance space 25 and the second clearance space 31 can be reasonably set according to actual conditions, and the utility model does not limit this.

[0038] Furthermore, one side of the boss portion 21 close to the bent portion 24 is connected to the first sheet body 22 in an arc shape to avoid stress concentration, thereby improving the structural strength of the bonding sheet 20 .

[0039] Of course, the number of bosses 21 on the same bonding sheet 20 is not limited to one. According to manufacturing requirements, a plurality of corresponding bosses 21 and hot pressing action areas 26 can be simultaneously provided on a bonding sheet 20 to sinter and weld multiple chips 10 respectively.

[0040] In some embodiments, a metal coating is disposed on the bonding surface 211 , wherein the metal coating may be gold or silver or other reasonable metal materials, and the metal coating may enhance the sintering quality between the bonding surface 211 and the chip 10 .

[0041] See also Figure 7 In some other embodiments, a sinking groove 26 is further provided in the hot pressing action area 26. The sinking groove 26 is formed by the sinking of the bonding sheet 20. The bonding sheet 20 of this structure can be formed by a stamping process. The design of the sinking groove 26 can reduce the material consumption of the bonding sheet 20 and reduce the manufacturing cost.

[0042] According to the second aspect of the utility model, a power module is provided, which includes the above-mentioned bonding structure. The bonding sheet 20 and the chip 10 are sintered and welded by hot pressing. With the structural design of the bonding sheet 20, the sintering and welding quality of the chip 10 and the bonding sheet 20 is guaranteed, and damage to the chip 10 during hot pressing and sintering is avoided. At the same time, various tolerance conflict problems can be solved, and the product yield rate is improved. The power module adopts the above-mentioned bonding structure to improve product quality and reliability.

[0043] In the bonding structure of the utility model, a sintering area is arranged on the chip, a boss portion and a hot pressing action area are arranged on the bonding sheet, and the projection of the bonding surface of the boss portion on the chip is in the sintering area, and the projection of the bonding surface on the bonding sheet is in the hot pressing action area. The bonding sheet and the chip are sintered and welded by hot pressing, which not only ensures the sintering and welding quality of the chip and the bonding sheet, but also avoids damage to the chip during hot pressing sintering, and can solve various tolerance conflict problems and improve product yield. The power module adopts the above bonding structure to improve product quality and reliability.

[0044] The present invention has been described by the above-mentioned relevant embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, any changes and modifications made without departing from the spirit and scope of the present invention are within the scope of patent protection of the present invention.

Claims

1. A bonding structure, characterized in that: The invention comprises a chip and a bonding sheet, wherein the bonding sheet and the chip are sintered and welded by hot pressing, a sintering zone is provided on the chip, and the bonding sheet is arranged above the chip; a boss portion is provided on a side of the bonding sheet close to the chip, and the boss portion protrudes from the bonding sheet in a direction toward the sintering zone; the boss portion has a bonding surface, and the bonding surface corresponds to a side surface of the boss portion close to the sintering zone, and the projection of the bonding surface on the chip is within the sintering zone; a hot pressing action zone is provided on a side of the bonding sheet away from the chip, and the projection of the bonding surface on the bonding sheet is within the hot pressing action zone, and the bonding surface and the sintering zone are sintered and welded by hot pressing in the hot pressing action zone.

2. The bonding structure according to claim 1, characterized in that: The bonding sheet comprises a first sheet body, a second sheet body and a bending portion, wherein the first sheet body and the second sheet body are connected via the bending portion; the boss portion and the hot pressing action area are respectively arranged on the first sheet body.

3. The bonding structure according to claim 2, characterized in that: A first clearance space is provided between the boss portion and the bending portion, and a second clearance space is provided between the hot pressing action zone and the bending portion.

4. The bonding structure according to claim 2, wherein: The side of the boss portion close to the bending portion is connected to the first sheet body in an arc shape.

5. The bonding structure according to claim 1, wherein: The bonding surface is provided with a metal coating.

6. The bonding structure according to claim 5, characterized in that: The metal plating layer is gold or silver.

7. The bonding structure according to claim 1, wherein: The sintering area is provided with bonding material, and the bonding material is used to sinter and weld the chip and the bonding sheet under the action of heat and pressure.

8. The bonding structure according to claim 7, wherein: The bonding material is silver, and the bonding sheet is a copper sheet.

9. The bonding structure according to claim 1, wherein: A sink is provided in the hot pressing action area.

10. A power module, characterized in that: Comprising a bonding structure as described in any one of claims 1 to 9.

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