阅读说明：本技术 功率元件封装结构 (Power element packaging structure ) 是由 蔡欣昌 刘敬文 于 2018-07-02 设计创作，主要内容包括：本发明提供一种功率元件封装结构,包括第一基板、第二基板、至少一功率元件以及封装体。第一基板的热导率大于200Wm<Sup>-1</Sup>K<Sup>-1</Sup>。功率元件配置于第一基板上。第二基板配置于第一基板下方。第二基板的热容量(heat capacity)大于第一基板的热容量。封装体封装第一基板、第二基板与功率元件。(The invention provides a power element packaging structure which comprises a first substrate, a second substrate, at least one power element and a packaging body. The first substrate has a thermal conductivity of more than 200Wm ‑1 K ‑1 . The power element is configured on the first substrate. The second substrate is arranged below the first substrate. The heat capacity of the second substrate is greater than the heat capacity of the first substrate. The packaging body packages the first substrate, the second substrate and the power element.)

1. A power device package, comprising:

a first substrate having a thermal conductivity of more than 200Wm^-1K^-1；

At least one power element configured on the first substrate;

a second substrate disposed below the first substrate, wherein a heat capacity of the second substrate is greater than a heat capacity of the first substrate; and

and the packaging body is used for packaging the first substrate, the second substrate and the power element.

2. The power element package structure of claim 1, wherein the material of the first substrate is one selected from the group consisting of copper, aluminum, gold, silver, diamond, or graphene, and alloy compounds thereof.

3. The power element package structure of claim 1, wherein the material of the second substrate is one selected from the group consisting of copper, aluminum, lithium, diamond, or graphene, and alloy compounds thereof.

4. The power element package structure of claim 1, wherein the second substrate has a thickness greater than a thickness of the first substrate.

5. The power element package structure of claim 1, wherein a volume of the second substrate is greater than a volume of the first substrate.

6. The power element package structure of claim 1, wherein a projected area of the second substrate is less than or equal to a projected area of the package body.

7. The power component package structure of claim 1, wherein the first substrate is copper and has a heat capacity greater than or equal to 0.5J ° c^-1。

8. The power component package structure of claim 7, wherein the second substrate is aluminum and has a heat capacity greater than or equal to 1.43J ° C^-1。

9. The power element package structure of claim 1, wherein the second baseThe heat capacity of the plate is greater than or equal to 0.5J DEG C^-1。

10. The power device package according to claim 1, wherein a portion of the first substrate and the second substrate are exposed outside the package body.

11. The power device package structure of claim 1, wherein the second substrate is disposed directly below the power device.

12. The power element package structure of claim 1, wherein the first substrate is in direct contact with the second substrate.

13. The power device package of claim 1, which is a power device package for a vehicle.

14. The power element package structure of claim 1, further comprising a control IC or circuit element disposed on the first substrate.

Technical Field

The present disclosure relates to package structures, and particularly to a power device package structure.

Background

The power element packaging structure can be used for rectifiers, automobile generators and high-power module generators. In the field of vehicle generators, a rectifier bridge is often provided to convert ac to dc. The rectifier bridge may be formed of a power element and may be configured to provide a rectified voltage as a basis for driving a load.

When the load of the generator is momentarily removed, a so-called load dump (load dump) phenomenon occurs. When the load rejection phenomenon occurs, due to the instant change of the voltage amplitude, an instant high heat is generated on the power device, so that the junction temperature (junction temperature) of the power device is instantly increased, which may cause the damage of the power device package structure.

However, most of the current designs of power device package structures aim to reduce the thermal resistance of the package structure in steady state use, that is, mainly reduce the steady state thermal resistance of the package structure, and there is no appropriate solution for transient thermal resistance related to instantaneous high heat.

Disclosure of Invention

The invention provides a power element packaging structure, which can reduce the steady-state thermal resistance of the power element packaging structure and can also reduce the transient thermal resistance of the power element packaging structure.

The invention discloses a power element packaging structure, which comprises a first substrate, a second substrate, at least one power element and a packaging body. Wherein the first substrate has a thermal conductivity of more than 200Wm^-1K^-1. The power element is configured on the first substrate. The second substrate is disposed below the first substrate, and a heat capacity (heat capacity) of the second substrate is greater than a heat capacity of the first substrate. The packaging body is used for packaging the first substrate, the second substrate and the power element.

In an embodiment of the invention, a material of the first substrate is selected from one of copper, aluminum, gold, silver, diamond, graphene, and an alloy compound thereof.

In an embodiment of the invention, a material of the second substrate is one selected from a group consisting of copper, aluminum, lithium, diamond, graphene, and alloy compounds thereof.

In an embodiment of the invention, a thickness of the second substrate is greater than a thickness of the first substrate.

In an embodiment of the invention, a volume of the second substrate is larger than a volume of the first substrate.

In an embodiment of the invention, a projection area of the second substrate is smaller than or equal to a projection area of the package.

In an embodiment of the invention, the first substrate is made of copper and has a heat capacity greater than or equal to 0.5J DEG C^-1。

In an embodiment of the invention, the second substrate is made of aluminum and has a heat capacity greater than or equal to 1.43J·℃^-1。

In an embodiment of the invention, the second substrate has a heat capacity of 0.5 J.DEG C or more^-1。

In an embodiment of the invention, a portion of the second substrate is exposed outside the package body.

In an embodiment of the invention, the second substrate is disposed directly below the power device.

In an embodiment of the invention, the first substrate directly contacts the second substrate.

In an embodiment of the invention, the power device package structure is a vehicle power device package structure.

In an embodiment of the invention, the power device package structure may further include a control IC or a circuit device disposed on the first substrate.

Based on the above, the second substrate with higher thermal capacity is matched with the first substrate with high thermal conductivity, so that the steady-state thermal resistance of the power element packaging structure can be reduced, the transient thermal resistance of the power element packaging structure can be reduced, and the processing capacity of the packaging structure on transient loads such as load rejection, short circuit and the like can be improved.

In order to make the aforementioned and other features and advantages of the invention more comprehensible, embodiments accompanied with figures are described in detail below.

Drawings

Fig. 1 is a schematic cross-sectional view of a power device package structure according to an embodiment of the invention.

Fig. 2A is a schematic front view of a power device package structure according to another embodiment of the invention.

Fig. 2B is a back view of fig. 2A.

Fig. 3 is a perspective view of the power element package structure of fig. 2A.

Fig. 4 is a graph showing the results of the load rejection tests of the experimental example and the comparative example.

Description of the reference numerals

100. 200: power element packaging structure

102. 202: second substrate

104. 204: first substrate

106. 206: power element

108. 208: package body

202a, 202b, 202c, 202d, 202e, 204a, 204b, 204 c: block

206a, 206b, 206c, 206 d: power transistor

210a, 210 b: reference grounding pin

212a, 212 b: phase output pin

214a, 214 b: power supply pin

216: pin block

218. 222: conductive structure

220: zener diode

224: control system

Detailed Description

Exemplary embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, but the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the size and thickness of regions, regions and layers may not be drawn to scale for clarity. For ease of understanding, like elements in the following description will be described with like reference numerals.

Fig. 1 is a schematic cross-sectional view of a power device package structure according to an embodiment of the invention.

Referring to fig. 1, the power device package structure 100 of the present embodiment includes a thermal conductivity greater than 200Wm^-1K^-1A first substrate 102, a second substrate 104, at least one power device 106, and a package 108. The material of the first substrate 102 is a high thermal conductivity material, for example, one selected from the group consisting of copper, aluminum, gold, silver, diamond, graphene, and alloy compounds thereof. The power device 106 is disposed on the first substrate 102. The second substrate 104 is disposed under the first substrate 102, and the second substrate 104 is preferably disposed directly under the power device 106. In the present embodiment, the heat capacity (heatcapacity) of the second substrate 104 is greater than that of the first substrate 102, and the heat capacity thereof is, for example, greater than or equal to0.5J·℃^-1. The material of the second substrate 104 is a high heat capacity material, for example, one selected from the group consisting of copper, aluminum, lithium, diamond, graphene, and alloy compounds thereof; preferably aluminum or an aluminum alloy. In one embodiment, the first substrate 102 is made of copper and has a heat capacity greater than or equal to 0.5 J.DEG C^-1(ii) a The second substrate 104 is made of aluminum and has a heat capacity of 1.43J DEG C or higher^-1。

In the present embodiment, the first substrate 102 and the second substrate 104 may be in direct contact; in another embodiment, a conductive adhesive layer (not shown) may be disposed between the first substrate 102 and the second substrate 104. In one embodiment, the thickness of the second substrate 104 is greater than the thickness of the first substrate 102 and/or the volume of the second substrate 104 is greater than the volume of the first substrate 102. The package 108 encapsulates the first substrate 102, the second substrate 104 and the power device 106, wherein a portion of the second substrate 104 is exposed outside the package 108 as shown in fig. 1. The projected area of the second substrate 104 is, for example, smaller than or equal to the projected area of the package 108. In the present embodiment, the material of the package body 108 is, for example, but not limited to, epoxy resin, biphenyl resin, unsaturated polyester, or ceramic material. The power device package 100 of the present embodiment may be a power device package for a vehicle.

When the power device package structure 100 of the present invention is applied to a rectifier of a vehicle generator, an alternating current continuously enters the power device package structure 100, and is converted into a direct current by the power device 106 and then output, and the heat energy generated during the conversion increases the temperature of the power device 106, so that the first substrate 102 with high thermal conductivity in this embodiment can reduce the steady-state thermal resistance. The thermal energy generated by the surge voltage (surge voltage) generated immediately after the load current is removed can be absorbed quickly by the second substrate 104 with high thermal capacity in this embodiment, so as to reduce the junction temperature of the power element 106.

For example, for an automobile generator with 50A power generation capacity, the transient energy generated when the load rejection phenomenon occurs is about 97.2J, if a copper lead frame is used as the first substrate 102 and an aluminum substrate is used as the second substrate 104In this embodiment, the heat capacity of the first substrate 102 is set to 0.5 J.DEG C^-1In this case, as long as the heat capacity of the second substrate 104 is greater than that of the first substrate 102, the junction temperature of the power element 106 is not higher than 350 ℃. In this embodiment, the heat capacity of the second substrate 104 can be further designed to be 1.43 J.DEG C^-1I.e. the junction temperature of the power device 106 is maintained not higher than 190 ℃, so as to ensure that the power device 106 is not damaged due to the excessive junction temperature.

Fig. 2A is a front view of a power device package structure according to another embodiment of the invention, and fig. 2B is a schematic diagram of a back view of fig. 2A. Fig. 3 is a perspective view of the power device package structure of fig. 2A, wherein the package body is omitted to clearly show the front structure of the power device package structure.

Referring to fig. 2A, fig. 2B and fig. 3, the power device package structure 200 of the present embodiment basically includes a thermal conductivity greater than 200Wm^-1K^-1A first substrate 202, a second substrate 204, a power device 206, and a package 208. The first substrate 202 in this embodiment is, for example, a lead frame, and may be composed of a plurality of blocks 202 a-202 e isolated from each other, wherein the block 202a has reference ground pins 210a and 210b, the block 202b has a phase output pin 212a, the block 202c has a phase output pin 212b, the block 202d has a power pin 214a, and the block 202e has a power pin 214 b. The power pins 214a and 214b may be coupled to the vehicle battery, the phase output pins 212a and 212b may generate a plurality of rectified signals, and the reference ground pins 210a and 210b may be coupled to the reference ground. When the package 208 encapsulates the first substrate 202, the second substrate 204 and the power device 206, the pins 210a, 210B, 212A, 212B, 214a, 214B protrude from the package 208, as shown in fig. 2A and 2B. The first substrate 202 may further include a plurality of pin blocks 216 separated from the block 202a, which can be connected to the first substrate 202 or devices thereon (e.g., the power device 206 or an external power source) via wire bonding, copper clip (copper clip) or other conductors. The material selection of the first substrate 202 in this embodiment can refer to the previous embodiment, and thus is not described again.

Referring to fig. 3, the power device 206 in the present embodiment is disposed on the first substrate 202. The power devices 206, such as power transistors 206 a-206 d, may include Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) or other power transistors. In the embodiment, the power devices 206 are respectively disposed on different blocks of the first substrate 202, but the invention is not limited thereto. Taking fig. 3 as an example, the power transistors 206a and 206b are disposed on the block 202b of the first substrate 202, and the power transistors 206c and 206d are disposed on the block 202c of the first substrate 202. The power transistor 206a may be electrically connected to the blocks 202a and 202b through a conductive structure 218, and a Zener diode (Zener diode)220 may be disposed on the block 202b and connected between one end (e.g., the drain) and the other end (e.g., the source) of the power transistor 206a through the conductive structure 218 to serve as a protection element of the power transistor 206a, but the invention is not limited thereto. In another embodiment, due to the presence of the second substrate 204, the power transistor 206a can be directly electrically connected to the block 202b of the first substrate 202 through the conductive structure 218 without providing the zener diode 220. The power transistor 206b may be electrically connected to the block 202d through the conductive structure 222.

The power transistor 206c can also be electrically connected to the block 202a and the block 202c through another conductive structure 218, and another zener diode 220 can be disposed on the block 202c and connected between one end (e.g., the drain) and the other end (e.g., the source) of the power transistor 206c through the conductive structure 218 to serve as a protection element of the power transistor 206c, but the invention is not limited thereto, and the zener diode 220 can be omitted, so as to directly solve the problem caused by the transient thermal resistance through the second substrate 204, and the power transistor 206c can be directly electrically connected to the block 202c of the first substrate 202 through the conductive structure 218. The power transistor 206d may be electrically connected to the block 202e through another conductive structure 222. The conductive structures 218 and 222 may be, for example, copper clips (clips) or other suitable structures.

In addition, the power device package 200 in this embodiment may further include a control system 224 (e.g., a control IC, a capacitor, and other circuit devices) disposed on the block 202a of the first substrate 202, and an insulating layer (not shown) disposed between the first substrate 202 and the control system 224 for electrically isolating the control system 224 from the first substrate 202 (i.e., the block 202a) therebelow. The control IC in the control system 224 is electrically connected to the power transistors 206a to 206d on the first substrate 202 via bonding wires (not shown) respectively, for transmitting control signals to the power transistors 206a to 206 d.

Referring to fig. 2B, the second substrate 204 in the present embodiment is disposed below the first substrate 202, and the first substrate 202 may directly contact the second substrate 204. In the embodiment, the second substrate 204 has three blocks 204a, 204b and 204c, and the block 204a is disposed directly below the power transistors 206a and 206b of fig. 3, the block 204b is disposed directly below the power transistors 206c and 206d of fig. 3, and the block 204c is disposed directly below the control system 224 of fig. 3, but the invention is not limited thereto. If the effect of reducing the transient thermal resistance is obtained, the second substrate 204 may be disposed right below the power element 206; in other words, block 204c may be omitted. In fig. 2B, a portion of the second substrate 204 is exposed outside the package body 208, and a projection area of the second substrate 204 does not exceed the package body 208. The material selection of the second substrate 204 can refer to the previous embodiment, and thus is not described in detail. The package 208 is formed by molding, for example, to seal the power device 206, the first substrate 202 and the second substrate 204. In the present embodiment, the material of the package body 208 may include epoxy resin, biphenyl resin, unsaturated polyester, or ceramic material.

After a large current enters the power transistors 206a to 206d from the reference ground pins 210a and 210b or the phase output pins 212a and 212b through the first substrate 202, the high junction temperature caused by the high heat instantaneously generated by the power transistors 206a to 206d can be reduced through the second substrate 204 with high heat capacity in this embodiment. Therefore, the design of the present embodiment can prevent the power device package structure 200 from being damaged.

To verify the above effects, the following experiments are given for explanation, but the present invention is not limited to the following experiments.

Experimental example

A power device package structure as shown in fig. 2A and 2B is fabricated, and then a load rejection test is performed according to ISO-7637-2 standard under the test conditions of the following table i and table ii, and after five times of tests, the interval of each test is 60 seconds, and the load rejection results after the tests are shown in the following table iii and fig. 4.

Comparative example

The difference between the comparative example and the experimental example is that the power element package structure of the comparative example does not include the second substrate. The above-described load rejection test was then performed in the same manner, and the results are shown in table three below and fig. 4.

Watch 1

Watch two

Watch III

	Examples of the experiments	Comparative example
			Heat capacity (J/. degree.C.)	2.5	1.0
Load rejection energy (J)	84.0	84.0
			Temperature elevation (. degree.C.)	171	278
Center temperature T of power elementj(℃)	193	300

As can be seen from the test results of fig. 4 and table three, since the power device package structure of the experimental example is provided with the second substrate with high heat capacity, when the same load rejection energy is applied, the temperature rise temperature of the experimental example is much lower than that of the comparative example, and the junction temperature of the power device of the experimental example is also much lower than that of the power device of the comparative example. Therefore, the second substrate with high heat capacity is arranged below the first substrate, so that the transient thermal resistance of the power element packaging structure can be really reduced, and the temperature rise reflected by the temperature rise and the junction temperature of the power element are remarkably improved.

In summary, the second substrate with higher thermal capacity is matched with the first substrate with high thermal conductivity in the power element packaging structure of the invention, so that the stable thermal resistance can be reduced, and the effect of reducing the transient thermal resistance can be achieved, so that the power element packaging structure of the invention is suitable for a rectifier or a motor driving device of a high-power vehicle generator.

Although the present invention has been described with reference to the above embodiments, it should be understood that the invention is not limited to the embodiments, and various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention.