Plastic package power module structure

Abstract

The invention provides a plastic package power module structure which comprises a substrate, the first layer of the substrate is a wiring layer, the second layer of the substrate is an insulating layer, and at least one plastic package body covers the upper surface of the wiring layer; the power chip is arranged on the substrate; the power terminal is of an integrally formed structure and is divided into a first metal section and a second metal section, and the thickness of the first metal section is larger than that of the second metal section; the power terminal is electrically connected with the power chip through the second metal section of the power terminal; the second metal sections and part of the first metal sections of the power terminals are covered by the plastic package body, and the rest of the first metal sections are exposed outside the plastic package body; and the power terminals are led out from the side surface of the plastic package body. According to the invention, the anti-vibration capability of the terminal of the plastic package power module can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a structure of a plastic-encapsulated power module. Background Art

[0002] Power modules are widely used in fields such as new energy vehicles, new energy power generation, smart grids, and transportation electrification. In some fields, such as new energy vehicle controllers, especially hybrid new energy vehicle controllers, higher requirements are imposed on the anti-vibration performance of power modules. The structural design of traditional power modules does not take into account the high-vibration application conditions of hybrid vehicles, and fatigue fracture of module terminals may occur under high-vibration conditions, resulting in module failure and potential safety hazards.

[0003] The T-pak module of Tesla is a plastic-encapsulated module, and the inside is a single transistor composed of two chips in parallel. The module terminals are connected to the electrodes on the chip surface and extend outside the module. The overall thickness of the module terminals is consistent. However, due to the low strength of the module terminals, fatigue fracture is likely to occur under high-vibration conditions, leading to module failure and potential safety hazards.

[0004] Therefore, how to improve the anti-vibration ability of power modules is the focus of attention of those skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide a structure of a plastic-encapsulated power module, which can improve the anti-vibration ability of the terminals of the power module.

[0006] To achieve the above object, the present invention provides a structure of a plastic-encapsulated power module, including:

[0007] A substrate, the first layer of the substrate is a wiring layer, the second layer is an insulating layer, and at least one plastic encapsulation body covers the upper surface of the wiring layer;

[0008] A power chip, disposed on the substrate;

[0009] Power terminals, the power terminals are integrally formed structures, divided into a first metal segment and a second metal segment, and the thickness of the first metal segment is greater than that of the second metal segment; the power terminals are electrically connected to the power chip through their second metal segments;

[0010] The second metal segment and part of the first metal segment of the power terminals are covered by the plastic encapsulation body, and the remaining first metal segments are exposed outside the plastic encapsulation body;

[0011] The power terminals are led out from the side surface of the plastic encapsulation body.

[0012] In an alternative embodiment, at the front end of the first metal segment, at the connection with the second metal segment, the thickness gradually transitions; or,

[0013] The thicknesses of the first metal segment and the second metal segment transition directly.

[0014] In an alternative embodiment, the encapsulated power module structure further includes a first signal terminal and a second signal terminal, and both the first signal terminal and the second signal terminal are electrically connected to the power chip.

[0015] In an alternative embodiment, the first signal terminal is a metal sheet with a uniform thickness, and is electrically connected to the power chip through a connecting wire. The thickness of the metal sheet is the same as the thickness of the first metal segment of the power terminal; and / or,

[0016] The second signal terminal is a metal sheet with a uniform thickness, and is electrically connected to the power chip through a connecting wire. The thickness of the metal sheet is the same as the thickness of the first metal segment of the power terminal.

[0017] In an alternative embodiment, the first signal terminal is an integrally formed structure, which is divided into a first metal segment and a second metal segment. The thickness of the first metal segment of the first signal terminal is greater than the thickness of the second metal segment. The first signal terminal is electrically connected to the power chip through its second metal segment; the second metal segment and a part of the first metal segment of the first signal terminal are both covered by the encapsulant, and the remaining first metal segment is exposed outside the encapsulant; and / or,

[0018] The second signal terminal is an integrally formed structure, which is divided into a first metal segment and a second metal segment. The thickness of the first metal segment of the second signal terminal is greater than the thickness of the second metal segment. The second signal terminal is electrically connected to the power chip through its second metal segment; the second metal segment and a part of the first metal segment of the second signal terminal are both covered by the encapsulant, and the remaining first metal segment is exposed outside the encapsulant.

[0019] In an alternative embodiment, the first signal terminal, the second signal terminal, and the power terminal are all separate entities; or, the first signal terminal is a separate entity, and the second signal terminal and the power terminal are an integral whole.

[0020] In an alternative embodiment, the power chip includes a first pole, a second pole, and a third pole;

[0021] The second metal segment of the power terminal is connected to the second pole of the power chip, the first signal terminal is connected to the third pole of the power chip, and the second signal terminal is connected to the second pole of the power chip;

[0022] The first pole of the power chip is connected to the wiring layer through a first solder layer.

[0023] In an alternative embodiment, the first signal terminal and the second signal terminal are welding terminals or crimping terminals.

[0024] In an alternative embodiment, the thickness of the second metal section of the power terminal is less than 0.5 mm, and the thickness of the first metal section is greater than 0.7 mm.

[0025] In an alternative embodiment, both the first signal terminal and the second signal terminal are led out from the side surface of the plastic package.

[0026] The beneficial effects of the present invention are as follows:

[0027] In the present invention, the power terminal has an integral structure with unequal thicknesses. The connection part between the power terminal and the chip surface is thinner, avoiding the reliability risks caused by the connection of thick terminals on the chip surface. At the same time, the external terminal is thicker, improving the anti-vibration ability of the terminals of the power module. Description of the Drawings

[0028] By describing the exemplary embodiments of the present invention in more detail in conjunction with the drawings, the above and other objects, features, and advantages of the present invention will become more apparent. In the exemplary embodiments of the present invention, the same reference numerals generally represent the same components.

[0029] Figure 1 It is a top view of a plastic-encapsulated power module structure in an embodiment of the present invention.

[0030] Figure 2 It is a side view of a plastic-encapsulated power module structure in an embodiment of the present invention.

[0031] Figure 3 It is a top view of another plastic-encapsulated power module structure in an embodiment of the present invention.

[0032] Figure 4 It is a side view of another plastic-encapsulated power module structure in an embodiment of the present invention.

[0033] Reference Numerals:

[0034] 1 - Plastic package; 20 - First signal terminal; 21 - Power terminal; 22 - Second signal terminal; 201 - First metal section; 202 - Second metal section. Detailed Embodiments

[0035] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments. According to the following description and drawings, the advantages and features of the present invention will be clearer. However, it should be noted that the concept of the technical solution of the present invention can be implemented in many different forms and is not limited to the specific embodiments described herein. The drawings are all in very simplified forms and use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0036] It should be understood that when an element or layer is referred to as "on", "adjacent to", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as "directly on", "directly adjacent to", "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or portions, these elements, components, regions, layers and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or portion from another element, component, region, layer or portion. Thus, without departing from the teachings of the present invention, the first element, component, region, layer or portion discussed below may be denoted as the second element, component, region, layer or portion.

[0037] Spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. are used herein for convenience in describing the relationship of one element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientation shown in the figures, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figures is flipped, then an element or feature described as "under" or "beneath" or "below" other elements or features will be oriented "on" the other elements or features. Thus, the exemplary terms "under" and "below" can include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientation) and the spatial descriptors used herein are to be interpreted accordingly.

[0038] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0039] Embodiment

[0040] Referring to Figures 1 to 4 , this embodiment provides a plastic-encapsulated power module structure, comprising:

[0041] A substrate, the first layer of the substrate being a wiring layer, the second layer being an insulating layer, and at least one encapsulant 1 covering the upper surface of the wiring layer;

[0042] A power chip, disposed on the substrate;

[0043] A power terminal 21, the power terminal 21 being an integrally formed structure, divided into a first metal segment 201 and a second metal segment 202, and the thickness of the first metal segment 201 being greater than the thickness of the second metal segment 202; the power terminal 21 is electrically connected to the power chip through its second metal segment 202;

[0044] The second metal segment 202 and a part of the first metal segment 201 of the power terminal 21 are both covered by the encapsulant 1, and the remaining first metal segment 201 is exposed outside the encapsulant 1; the power terminal is led out from the side of the encapsulant 1.

[0045] In this embodiment, the encapsulated power module structure further includes a first signal terminal 20 and a second signal terminal 22, and both the first signal terminal 20 and the second signal terminal 22 are electrically connected to the power chip. Both the first signal terminal 20 and the second signal terminal 22 are led out from the side of the encapsulant 1.

[0046] In this embodiment, the first signal terminal 20 is an integrally formed structure, divided into a first metal segment and a second metal segment, and the thickness of the first metal segment of the first signal terminal 20 is greater than the thickness of the second metal segment. The first signal terminal 20 is electrically connected to the power chip through its second metal segment; the second metal segment and a part of the first metal segment of the first signal terminal 20 are both covered by the encapsulant 1, and the remaining first metal segment is exposed outside the encapsulant 1; the second signal terminal 22 is an integrally formed structure, divided into a first metal segment and a second metal segment, and the thickness of the first metal segment of the second signal terminal 22 is greater than the thickness of the second metal segment. The second signal terminal 22 is electrically connected to the power chip through its second metal segment; the second metal segment and a part of the first metal segment of the second signal terminal 22 are both covered by the encapsulant 1, and the remaining first metal segment is exposed outside the encapsulant 1.

[0047] In another embodiment, the first signal terminal is a metal sheet with equal thickness, electrically connected to the power chip through a connecting wire, and the thickness of the metal sheet is the same as the thickness of the first metal segment of the power terminal; the second signal terminal is a metal sheet with equal thickness, electrically connected to the power chip through a connecting wire, and the thickness of the metal sheet is the same as the thickness of the first metal segment of the power terminal.

[0048] In this embodiment, at the connection between the front end of the first metal section of the power terminal 21 / the first signal terminal 20 / the second signal terminal 22 and the second metal section, the thickness gradually transitions. In other embodiments, the connection between the two can also be a direct transition.

[0049] Figure 1 and Figure 2 in, the first signal terminal 20 is an individual entity, and the second signal terminal 22 and the power terminal 21 are an integral whole. Figure 3 and Figure 4 in, the first signal terminal 20, the second signal terminal 22, and the power terminal 21 are all separate entities. The first signal terminal 20 and the second signal terminal 22 can be welding terminals or crimping terminals.

[0050] The insulating layer material of the substrate can be insulating materials such as alumina, aluminum nitride, zirconia, silicon nitride, epoxy resin, silicone, etc.

[0051] The power chip can be a diode chip (Diode chip), a metal-oxide-semiconductor field-effect transistor chip (MOSFET chip), an insulated-gate bipolar transistor chip (IGBT chip), a high electron mobility transistor chip (HEMT chip), a junction field-effect transistor chip (JFET chip), a bipolar junction transistor chip (BJT chip), or a thyristor chip (SCR chip).

[0052] When the power chip is a MOSFET chip, the power chip includes a first pole, a second pole, and a third pole; the first pole is the drain, the second pole is the source, and the third pole is the gate. The second metal section 202 of the power terminal 21 is all connected to the second pole of the power chip, the second metal section of the first signal terminal 20 is connected to the third pole of the power chip, the second metal section of the second signal terminal 22 is connected to the second pole of the power chip, and the first pole of the power chip is connected to the wiring layer through a first solder layer. The first solder layer can be a material with conductivity such as sintered silver, solder, conductive silver glue, etc.

[0053] In this embodiment, the material of the power terminal is copper. The thickness of the second metal section 202 of the power terminal is less than 0.5 mm, and the thickness of the first metal section 201 is greater than 0.7 mm. The power terminal 21, the first signal terminal 20, and the second signal terminal 22 are all led out from the side of the plastic package 1.

[0054] The terminal width / thickness design of traditional power modules is dominated by electrical performance and is prone to fracture failure in a vibrating environment. The existing terminal structure has a large response in the XYZ three-axis sweep frequency and random superposition vibration tests, resulting in obvious stress concentration at the terminal-module package interface. The terminals in this embodiment adopt an integral structure with unequal thickness, which not only solves the reliability risk caused by the connection of thick copper on the chip surface but also improves the vibration resistance of the terminals. Taking the thickness of the first metal segment increased from 0.4 mm to 0.8 mm as an example, under the same vibration conditions (random vibration, 50 - 2000 Hz equivalent 6.8 G acceleration load), the vibration resistance performance is significantly improved. The number of failure cycles is increased from about 10^5 times of the traditional structure to more than 10^6 times, and the first-order natural frequency is also increased by about 20%, with the resonance in the low-frequency band improved.

[0055] In addition, when the terminals are led out from the side of the plastic package instead of the traditional front side, the maximum stress at the terminal root is reduced from about 180 MPa to about 55 MPa, which is lower than the fatigue limit of the material (taking pure copper as an example and considering the fatigue limit at 30% of the yield strength).

[0056] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A plastic-encapsulated power module structure, characterized in that: include: A substrate, wherein the first layer of the substrate is a wiring layer, the second layer is an insulating layer, and at least one plastic package body covers the upper surface of the wiring layer; A power chip is arranged on the substrate; A power terminal, wherein the power terminal is an integrally formed structure, and is divided into a first metal segment and a second metal segment, and the thickness of the first metal segment is greater than the thickness of the second metal segment; the power terminal is electrically connected to the power chip through its second metal segment; The second metal segment and part of the first metal segment of the power terminal are covered by the plastic package, and the remaining first metal segment is exposed outside the plastic package; The power terminal is led out from the side surface of the plastic package body.

2. The plastic-encapsulated power module structure according to claim 1, characterized in that: The thickness of the front end of the first metal segment and the connection with the second metal segment gradually transitions; or, The thickness of the first metal segment and the second metal segment directly transition.

3. The plastic-encapsulated power module structure according to claim 1, characterized in that: The plastic-encapsulated power module structure further includes a first signal terminal and a second signal terminal, and the first signal terminal and the second signal terminal are both electrically connected to the power chip.

4. The plastic-encapsulated power module structure according to claim 3, characterized in that: The first signal terminal is a metal sheet of equal thickness, electrically connected to the power chip via a connecting wire, and the thickness of the metal sheet is the same as the thickness of the first metal segment of the power terminal; and / or, The second signal terminal is a metal sheet of equal thickness, which is electrically connected to the power chip via a connecting wire, and the thickness of the metal sheet is the same as the thickness of the first metal segment of the power terminal.

5. The plastic-encapsulated power module structure according to claim 3, characterized in that: The first signal terminal is an integrally formed structure, and is divided into a first metal segment and a second metal segment, and the thickness of the first metal segment of the first signal terminal is greater than the thickness of the second metal segment, and the first signal terminal is electrically connected to the power chip through its second metal segment; the second metal segment and part of the first metal segment of the first signal terminal are both covered by the plastic package, and the remaining first metal segment is exposed outside the plastic package; and / or, The second signal terminal is an integrally formed structure, which is divided into a first metal segment and a second metal segment, and the thickness of the first metal segment of the second signal terminal is greater than the thickness of the second metal segment, and the second signal terminal is electrically connected to the power chip through its second metal segment; the second metal segment and part of the first metal segment of the second signal terminal are covered by the plastic package, and the remaining first metal segment is exposed outside the plastic package.

6. The plastic-encapsulated power module structure according to claim 5, characterized in that: The first signal terminal, the second signal terminal and the power terminal are all separate entities; or, the first signal terminal is a separate entity, and the second signal terminal and the power terminal are a whole.

7. The plastic-encapsulated power module structure according to claim 3, characterized in that: The power chip comprises a first pole, a second pole and a third pole; The second metal segment of the power terminal is connected to the second pole of the power chip, the first signal terminal is connected to the third pole of the power chip, and the second signal terminal is connected to the second pole of the power chip; The first electrode of the power chip is connected to the wiring layer through a first solder layer.

8. The plastic-encapsulated power module structure according to claim 3, characterized in that: The first signal terminal and the second signal terminal are welding terminals or crimping terminals.

9. The plastic-encapsulated power module structure according to claim 1, characterized in that: The thickness of the second metal segment of the power terminal is less than 0.5 mm, and the thickness of the first metal segment is greater than 0.7 mm.

10. The plastic-encapsulated power module structure according to claim 3, characterized in that: The first signal terminal and the second signal terminal are both led out from the side surface of the plastic package body.

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