A power package structure and a power module

Abstract

This invention provides a power packaging structure and power module, including a substrate, a power chip, several conductive pillars, a molding compound, and several front-side lead-out terminals. The conductive pillars are sequentially divided into a first structure and a second structure along a direction away from the top surface of the substrate, and the bottom surface of the first structure is fixed to the electrode lead-out area on the top surface of the substrate. Since the cross-sectional area of ​​the first structure is smaller than that of the second structure of the conductive pillars, and several conductive pillars are fixed to the top surface of the substrate, the space requirement for the conductive pillars on the substrate is greatly reduced by decreasing the contact area between a single conductive pillar and the top surface of the substrate, thereby reducing the size of the substrate and consequently lowering the packaging cost.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuits, and in particular to a power packaging structure and a power module. Background Technology

[0002] Power chip packaging is a key technology for connecting power semiconductor devices (such as IGBTs, MOSFETs, and SiC / GaN devices) to external circuits and providing mechanical protection, heat dissipation, and electrical isolation. Its design must balance high power density, heat dissipation efficiency, reliability, and cost.

[0003] In the existing power chip package structure with front-side pins, the molded body slots that expose the substrate are only formed at the locations where signal output is required, and corresponding signal output structures are set in the slots to output the power chip's output signals to the outside.

[0004] However, existing power package structures with front-facing leads suffer from high packaging costs due to large substrate size. Utility Model Content

[0005] This invention provides a power packaging structure and power module to reduce substrate size and thus reduce packaging costs.

[0006] To solve the above-mentioned technical problems, according to a first aspect of the present invention, a power packaging structure is provided, comprising: A substrate, wherein an electrode lead-out area is provided on the top surface of the substrate, the electrode lead-out area being used to lead out circuits in the substrate; A power chip, which is fixed to the top surface of the substrate and electrically connected to the circuit; A plurality of conductive pillars, wherein the conductive pillars have a first structure and a second structure connected in their extension direction, the bottom surface of the first structure is fixed to the electrode lead-out area, the cross-sectional area of ​​the first structure is smaller than the cross-sectional area of ​​the second structure, and the first structure and the second structure are an integral structure. A molding compound that covers the top surface of the substrate, the power chip, and the conductive pillars, and exposes the top surface of the second structure; A plurality of front-facing leads are provided, and the plurality of front-facing leads correspond one-to-one with the plurality of conductive posts. The front-facing leads are fixed to the top surface of the second structure corresponding to the conductive posts.

[0007] Optionally, the first structure includes at least a frustum, a cylinder, or a polygonal prism; if the first structure is a frustum, then the bottom surface of the first structure is the lower bottom surface of the frustum.

[0008] Optionally, the second structure includes at least a cylinder or a polygonal cylinder.

[0009] Optionally, the conductive post is provided with a groove, and the opening of the groove is located on the top surface of the second structure; The front lead-out terminal is vertically fixed in the groove, and the cross-sectional shape of the front lead-out terminal is the same as the opening shape of the groove.

[0010] Optionally, the front lead-out terminal is welded inside the groove, and the front lead-out terminal is welded to the bottom of the groove and / or the sidewall of the groove.

[0011] Optionally, the top surface of the second structure is higher than the surface of the encapsulated body.

[0012] Optionally, the power packaging structure further includes a heat dissipation structure disposed on the bottom surface of the substrate, wherein the top and bottom surfaces of the substrate are opposite each other.

[0013] Optionally, the substrate type includes direct copper-clad ceramic substrate, active metal brazing ceramic substrate, or DBC-AMB composite laminate substrate.

[0014] Optionally, the power chip circuit includes at least a MOSFET, an IGBT, a diode, or a thyristor.

[0015] Optionally, the heights of the conductive pillars may be different, so that the top surfaces of the second structure in the conductive pillars are all on the same horizontal plane.

[0016] According to a second aspect of the present invention, a power module is also provided, including the power packaging structure provided in the first aspect of the present invention.

[0017] Compared with the prior art, the technical solution provided by this utility model has the following beneficial effects: The power packaging structure provided by this utility model has conductive pillars arranged in a direction away from the top surface of the substrate, dividing it into a first structure and a second structure. The bottom surface of the first structure is fixed to the electrode lead-out area on the top surface of the substrate. Since the cross-sectional area of ​​the first structure is smaller than that of the second structure of the conductive pillars, and since several conductive pillars are fixed on the top surface of the substrate, the space requirement of the conductive pillars on the substrate is greatly reduced by decreasing the contact area between a single conductive pillar and the top surface of the substrate. This reduces the size of the substrate and thus lowers the packaging cost.

[0018] Furthermore, the first structure for setting the conductive post is a frustum, with the bottom surface of the first structure being the lower bottom surface. Since the frustum facilitates the flow of the encapsulant, it provides greater sealing for the conductive post, thereby improving the leakage protection capability of the power package structure. In addition, during the encapsulation process of the conductive post, the frustum effectively prevents stress concentration, thus avoiding device failure caused by stress concentration.

[0019] Furthermore, since the front lead-out terminal is fixed on the top surface of the second structure corresponding to the conductive post, the second structure for setting the conductive post includes a cylindrical or polygonal column to adapt the conductive post to the shape of the front lead-out terminal and the space requirements of the front lead-out terminal, thereby improving the compatibility of power packaging.

[0020] Furthermore, a groove is provided inside the conductive post, with the opening of the groove located on the top surface of the second structure. The cross-sectional shape of the front lead terminal is the same as the shape of the groove opening, and the cross-sectional area of ​​the front lead terminal is less than or equal to the size of the groove. The front lead terminal is vertically fixed in the groove to increase the welding area between the front lead terminal and the second structure, thereby improving the vibration resistance of the front lead terminal. In addition, the groove also plays a role in positioning and guiding the fixation of the front lead terminal.

[0021] Furthermore, by setting the top surface of the second structure higher than the surface of the molded package, the difficulty of fixing the front-side leads to the top surface of the second structure corresponding to the conductive pillars is greatly reduced. In addition, by setting the top surface of the second structure lower than the surface of the molded package, the creepage distance between the front-side leads is increased, thereby reducing the short-circuit risk of the power package.

[0022] Furthermore, the different heights of the conductive pillars ensure that the top surfaces of the second structure in each conductive pillar are on the same horizontal plane, matching the height requirements of the conductive pillars to be fixed in different positions. This allows the externally connected terminals to use products of uniform specifications, reducing the overall module cost. Attached Figure Description

[0023] Figure 1 Schematic cross-sectional view of the power packaging structure provided in the first embodiment of this utility model Figure 1 ; Figure 2 A three-dimensional structural schematic diagram of the conductive column provided in the first embodiment of this utility model; Figure 3 A three-dimensional structural schematic diagram of a conductive post provided for another embodiment of this utility model; Figure 4 A top view of a power packaging structure provided in another embodiment of this utility model; Figure 5A three-dimensional structural schematic diagram of a conductive post provided in another embodiment of this utility model; Figure 6 A top view schematic diagram of a power packaging structure provided in another embodiment of this utility model; Figure 7 A three-dimensional structural schematic diagram of the conductive column provided in the second embodiment of this utility model; Figure 8 A cross-sectional view of the power packaging structure provided in the second embodiment of this utility model; Figure 9 A cross-sectional schematic diagram of the power packaging structure provided in the third embodiment of this utility model; Figure 10 yes Figure 9 A schematic diagram of the three-dimensional structure; Figure 11 A cross-sectional view of a power packaging structure provided in another embodiment of the present invention; Figure 12 for Figure 11 A schematic diagram of the three-dimensional structure. Detailed Implementation

[0024] As mentioned in the background section, existing power packaging structures with front-side pins suffer from high packaging costs due to large substrate size.

[0025] In view of this, the technical solution of this utility model provides a new power packaging structure. In the power packaging structure, several conductive pillars are sequentially divided into a first structure and a second structure along the direction away from the top surface of the substrate. Since the bottom surface of the first structure is fixed to the electrode lead-out area of ​​the top surface of the substrate, and the cross-sectional area of ​​the first structure is smaller than that of the second structure, the space requirement of several conductive pillars on the substrate is greatly reduced, thereby reducing the size of the substrate and thus reducing the packaging cost.

[0026] To make the above-mentioned objectives, features, and beneficial effects of this utility model more apparent and understandable, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices.

[0027] [First Embodiment] Figure 1 Schematic cross-sectional view of the power packaging structure provided in the first embodiment of this utility model Figure 1 .

[0028] Please refer to Figure 1 The power packaging structure provided in this embodiment includes a substrate 10, a power chip, several conductive pillars 20, a molding compound 30, and several front-side lead-out terminals 40.

[0029] The top surface of the substrate 10 is provided with an electrode lead-out area, which is used to lead out the circuit in the substrate 10.

[0030] Specifically, the substrate 10 includes a direct copper-clad ceramic substrate, an active metal brazed ceramic substrate, or a DBC-AMB composite laminate substrate. Of course, besides the copper-clad ceramic substrate, the substrate 10 may also include a metal substrate, a resin substrate, etc., and is not limited here. For ease of explanation, in this embodiment, substrate 10 will refer to the copper-clad ceramic substrate.

[0031] Specifically, the circuit is formed by dividing the copper plating on the top surface of the substrate 10 into etched grooves. This can be understood as etching predetermined grooves into the copper plating on the top surface of the substrate 10 to form the circuit. The specific pattern of the circuit is related to the topology of the power chip in the actual package and is not limited here.

[0032] The power chip is fixed to the top surface of the substrate 10, and the power chip is electrically connected to the circuit.

[0033] Specifically, the power chip includes at least one or more of MOSFETs, IGBTs, diodes, and thyristors. Since the number and type of power chips are related to the specific topology, the number and type of the first power chip are not limited here. Electrically connecting the power chip to the circuitry on the substrate 10 is a conventional technique in the art and will not be elaborated upon here.

[0034] The conductive post 20 has a first side and a second side facing each other. The conductive post 20 is divided into a first structure 22 and a second structure 21 in a direction away from the top surface of the substrate 10. The bottom surface of the first structure 22 is fixed to the electrode lead-out area on the top surface of the substrate 10. The cross-sectional area of ​​the first structure 22 is smaller than the cross-sectional area of ​​the second structure 21. The first structure 22 and the second structure 21 are an integral whole. The bottom surface of the first structure 22 is the first side of the conductive post 20, and the top surface of the second structure 21 is the second side of the conductive post 20.

[0035] In this embodiment, the material of the conductive post 20 includes copper, aluminum or other conductive materials, which are not limited here.

[0036] Figure 2 Schematic diagram of the conductive post provided in the first embodiment of this utility model Figure 1 .

[0037] Please refer to Figure 2 In this embodiment, the first structure 22 of the conductive post 20 is a frustum, and the bottom surface of the first structure 22 is the lower bottom surface of the frustum. Since the frustum facilitates the flow of the encapsulating body 30, the encapsulation of the conductive post 20 has higher sealing performance, thereby improving the leakage protection capability of the power packaging structure. Furthermore, during the encapsulation process of the conductive post 20 by the encapsulating body 30, the frustum effectively prevents stress concentration, thus avoiding device failure caused by stress concentration. Of course, in other embodiments, besides the frustum, the first structure 22 may also include a cylinder or a polygonal cylinder, which is not limited here.

[0038] Please continue to refer to this. Figure 2 In this embodiment, the second structure 21 of the conductive post 20 is a cylinder. To accommodate different sizes of the substrate 10, different shapes of the front-side lead-out terminals 40, and different space requirements of the front-side lead-out terminals 40, in other embodiments, the second structure 21 can also be configured as a hexagonal prism, such as... Figure 3 and Figure 4As shown; or the second structure 21 can also be configured as a quadrilateral prism, such as Figure 5 and Figure 6 As shown. Of course, the specific structure of the second structure 21 can be selected according to actual needs, and is not limited here.

[0039] The second structure 21 of the conductive post 20 is set to different shapes according to different needs, which has the following effects: setting the cross-sectional shape of the second structure 21 of the conductive post 20 to be the same as the cross-sectional shape of the front lead terminal can reduce the difficulty of fixing the front lead terminal and improve the adaptability of fixing the front lead terminal to the top surface of the second structure 21.

[0040] Furthermore, the cross-sectional shape of the first structure 22 of the conductive post 20 can be adapted to the shape of the substrate to improve the utilization rate of the substrate plane. Since different substrates have different shapes, the substrate shape is not always a regular rectangle; irregular shapes also exist, such as protruding or recessed structures. Therefore, the cross-sectional shape of the first structure 22 of the conductive post 20 can be set to be the same as the shape of the protruding or recessed structure of the substrate, thereby improving the utilization rate of the substrate plane.

[0041] The molding compound 30 covers the top surface of the substrate 10, the power chip, and the conductive pillar 20, and exposes the top surface of the second structure 21.

[0042] Please continue to refer to this. Figure 1 In this embodiment, the surface of the encapsulant 30 and the top surface of the second structure 21 of the conductive post 20 are on the same horizontal plane. The material of the encapsulant 30 includes epoxy resin.

[0043] The plurality of front lead-out terminals 40 and the plurality of conductive posts 20 correspond one-to-one, and the front lead-out terminals 40 are fixed on the top surface of the second structure 21 corresponding to the conductive post 20.

[0044] Please continue to refer to this. Figure 1 In this embodiment, the front lead-out terminal 40 is directly fixed to the top surface of the second structure 21. The fixing method includes laser welding, ultrasonic welding, or solder paste brazing, etc., which are not limited here.

[0045] Please continue to refer to this. Figure 1 In this embodiment, the power packaging structure further includes a heat dissipation structure, which is disposed on the bottom surface of the substrate 10, and the top and bottom surfaces of the substrate 10 are opposite to each other.

[0046] In practical applications, the conductive pillars may be placed on the substrate surface at different heights. For example, the substrate surface may be provided with a stacked substrate, with some conductive pillars placed on the substrate surface and others on the stacked substrate surface. Therefore, in order to match the height requirements of the conductive pillars being fixed at different positions, in this embodiment, several conductive pillars are set to have different heights so that the top surfaces of the second structure in several conductive pillars are all on the same horizontal plane. This allows the externally connected terminals to use products of uniform specifications, reducing the overall module cost.

[0047] In summary, the power packaging structure provided in this embodiment, since the cross-sectional area of ​​the first structure is smaller than that of the second structure of the conductive pillar, and several conductive pillars are fixed on the top surface of the substrate, greatly reduces the space requirement of the conductive pillars on the substrate by reducing the contact area between a single conductive pillar and the top surface of the substrate, thereby reducing the size of the substrate and thus reducing the packaging cost.

[0048] Furthermore, the first structure of the conductive post is a frustum, with the bottom surface of the first structure being the lower bottom surface. Since the frustum facilitates the flow of the encapsulating material, the encapsulation of the conductive post has higher sealing performance, thereby improving the leakage protection capability of the power package structure. In addition, during the encapsulation process of the conductive post, the frustum effectively prevents stress concentration, thus avoiding device failure caused by stress concentration.

[0049] [Second Embodiment] This embodiment is an improved version of the first embodiment. Please refer to it. Figure 7 and Figure 8 The difference between this embodiment and the first embodiment is that a groove 63 is provided inside the conductive post 20, and the opening of the groove 63 is located on the top surface of the second structure 61.

[0050] The cross-sectional shape of the front lead-out terminal 40 is the same as the opening shape of the groove 63, and the cross-sectional area of ​​the front lead-out terminal 40 is less than or equal to the opening size of the groove 63, so that the front lead-out terminal 40 can be directly inserted into the groove 63 and welded into the groove 63. Alternatively, in other embodiments, the cross-sectional area of ​​the front lead-out terminal 40 may be larger than the opening size of the groove 63, and an interference fit may be used to fix the front lead-out terminal 40 and the groove 63.

[0051] In this embodiment, the front lead-out terminal 40 is welded only to the bottom of the groove 63. In other embodiments, the front lead-out terminal 40 is welded to both the bottom of the groove 63 and the sidewall of the groove 63, or is fixed only to the sidewall of the groove 63. Of course, regardless of whether the front lead-out terminal 40 is welded to the bottom and / or sidewall of the groove 63, the welding area between the front lead-out terminal 40 and the second structure 61 is increased, thereby improving the vibration resistance of the front lead-out terminal 40. Furthermore, the groove 63 also provides positioning and guidance for fixing the front lead-out terminal 40. The process of fixing the front lead-out terminal 40 within the groove 63 is the same as that of fixing the front lead-out terminal 40 to the top surface of the second structure 21 in the first embodiment, and will not be described again here.

[0052] [Third Embodiment] This embodiment is an improved version of the first embodiment. Please refer to 9 and... Figure 10 The difference between this embodiment and the first embodiment is that the top surface of the second structure 21 is higher than the surface of the encapsulated body 70.

[0053] Because the top surface of the second structure 21 is higher than the surface of the molding compound 70, the difficulty of fixing the front lead terminals to the top surface of the second structure corresponding to the conductive post is greatly reduced. Furthermore, by setting the top surface of the second structure 21 lower than the surface of the molding compound 70, the creepage distance between the front lead terminals is increased, thereby reducing the short-circuit risk of the power package.

[0054] Specifically, the distance between the top surface of the second structure 21 and the surface of the molding compound 70 is between 0.05 mm and 0.5 mm. Of course, the specific value of this distance can be modified according to actual needs, and is not limited here.

[0055] In other embodiments, the top surface of the second structure 21 may also be lower than the surface of the molding compound 70, specifically as follows: Figure 11 and Figure 12 As shown.

[0056] It should be noted that, for ease of illustration, Figure 10 and Figure 12 The heat sink structure is not shown in any of them.

[0057] Accordingly, this utility model embodiment also provides a power module, including the power packaging structure described in any of the above embodiments.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A power package structure, characterized by, include: A substrate, wherein an electrode lead-out area is provided on the top surface of the substrate, the electrode lead-out area being used to lead out circuits in the substrate; A power chip, which is fixed to the top surface of the substrate and electrically connected to the circuit; A plurality of conductive pillars, wherein the conductive pillars have a first structure and a second structure connected in their extension direction, the bottom surface of the first structure is fixed to the electrode lead-out area, the cross-sectional area of ​​the first structure is smaller than the cross-sectional area of ​​the second structure, and the first structure and the second structure are an integral structure; A molding compound that covers the top surface of the substrate, the power chip, and the conductive pillars, and exposes the top surface of the second structure; A plurality of front-facing leads are provided, and the plurality of front-facing leads correspond one-to-one with the plurality of conductive posts. The front-facing leads are fixed to the top surface of the second structure corresponding to the conductive posts.

2. The power package structure of claim 1, wherein, The first structure includes at least a frustum, a cylinder, or a polygonal cylinder. If the first structure is a frustum, then the bottom surface of the first structure is the bottom surface of the frustum.

3. The power package structure of claim 1, wherein, The second structure includes at least a cylinder or a polygonal cylinder.

4. The power packaging structure according to claim 1, characterized in that, The conductive post has a groove inside, and the opening of the groove is located on the top surface of the second structure; The front lead-out terminal is vertically fixed in the groove, and the cross-sectional shape of the front lead-out terminal is the same as the opening shape of the groove.

5. The power packaging structure according to claim 4, characterized in that, The front lead-out terminal is welded inside the groove, and the front lead-out terminal is welded to the bottom of the groove and / or the sidewall of the groove.

6. The power packaging structure according to claim 1, characterized in that, The top surface of the second structure is higher than the surface of the encapsulated body.

7. The power packaging structure according to claim 1, characterized in that, The power packaging structure also includes a heat dissipation structure disposed on the bottom surface of the substrate, with the top and bottom surfaces of the substrate facing each other.

8. The power packaging structure according to claim 1, characterized in that, The substrate types include direct copper-clad ceramic substrates, active metal brazed ceramic substrates, or DBC-AMB composite stacked substrates.

9. The power packaging structure according to claim 1, characterized in that, The types of chips include at least MOSFETs, IGBTs, diodes, or thyristors.

10. The power packaging structure according to claim 1, characterized in that, The heights of the conductive pillars are different so that the top surfaces of the second structure in the conductive pillars are all on the same horizontal plane.

11. A power module, characterized in that, Includes the power packaging structure according to any one of claims 1 to 10.

Images