CN106558568A - Package structure - Google Patents

Abstract

A package structure includes a package body, an active device, a first lead frame and a second lead frame. The active element is packaged in the packaging body. The active device includes a first electrode and a second electrode. The first electrode is arranged on the first lead frame and is electrically connected with the first lead frame. The first lead frame has a first exposed surface. The first exposed surface and the first electrode are respectively positioned on the opposite sides of the first lead frame. The first exposed surface is exposed outside the packaging body. The second electrode is arranged on the second lead frame and is electrically connected with the second lead frame. The second lead frame has a second exposed surface. The second exposed surface and the second electrode are respectively positioned on the opposite sides of the second lead frame. The second exposed surface is exposed outside the packaging body. The shortest distance from the first electrode to the second electrode is smaller than the shortest distance from the first exposed surface to the second exposed surface.

Description

Package structure

technical field

The invention relates to a packaging structure.

Background technique

With the rapid and vigorous development of information technology, the miniaturization trend of electronic devices has become a trend. Therefore, on the circuit board, the integration degree of electronic components is increasing day by day, which makes the problem of heat dissipation of electronic components more important.

Furthermore, power transistors are common basic components in electronic devices such as power supply devices, control equipment, measuring instruments, electrical equipment, and computer peripheral equipment. Since their main functions are signal processing or power driving, and are usually processing Higher power signals generate more heat, so the need for heat dissipation is particularly important.

Generally speaking, the heat dissipation of power transistors is usually achieved by the shape design of the lead frame. In addition to the problem of heat dissipation, due to the high signal power passing through the high-power transistors, the lead frames connected to different electrodes are relatively prone to short circuits. Therefore, the design of the lead frame must also meet the requirements of short circuit protection. Therefore, how to balance heat dissipation and short-circuit protection requirements of power transistors is one of the important issues in related fields.

Contents of the invention

In one embodiment of the present invention, a packaging structure is provided that can meet the requirements of heat dissipation and short-circuit prevention of active components.

According to an embodiment of the present invention, a package structure includes a package body, an active device, a first lead frame and a second lead frame. The active components are encapsulated in the package body. The active device includes a first electrode and a second electrode. The first electrode is disposed on the first lead frame and electrically connected to the first lead frame. The first lead frame has a first exposed surface. The first exposed surface and the first electrode are respectively located on opposite sides of the first lead frame. The first exposed surface is exposed outside the package body. The second electrode is disposed on the second lead frame and is electrically connected to the second lead frame. The second lead frame has a second exposed surface. The second exposed surface and the second electrode are respectively located on opposite sides of the second lead frame. The second exposed surface is exposed outside the package body. The shortest distance from the first electrode to the second electrode is smaller than the shortest distance from the first exposed surface to the second exposed surface.

In the above embodiments, since the first lead frame and the second lead frame respectively have a first exposed surface and a second exposed surface exposed outside the package, the heat of the active device can be conducted to the package. In addition, since the shortest distance from the first exposed surface to the second exposed surface is longer than the shortest distance from the first electrode to the second electrode, the first exposed surface may not be too close to the second exposed surface. In this way, even if the first electrode and/or the second electrode of the active element transmits a high-power signal, which may cause arcing on the first exposed surface and the second exposed surface exposed in the air, the first exposed surface and the second exposed surface The distance between the exposed surfaces is long enough to prevent arcing between the first exposed surface and the second exposed surface, thereby further preventing the arc from causing a short circuit between the first electrode and the second electrode. Therefore, in the above-mentioned embodiments, the heat dissipation and short-circuit prevention requirements of the active element can be taken into account.

The above description is only used to illustrate the problem to be solved by the present invention, the technical means for solving the problem and the effects thereof, etc., and the specific details of the present invention will be introduced in detail in the following embodiments and related drawings.

Description of drawings

In order to make the embodiments of the present invention more obvious and understandable, the accompanying drawings are described as follows:

FIG. 1 shows a schematic perspective view of a packaging structure according to an embodiment of the present invention;

Fig. 2 depicts a schematic cross-sectional view along line 2-2' in Fig. 1;

3 shows a schematic cross-sectional view of a packaging structure according to another embodiment of the present invention;

4 shows a schematic cross-sectional view of a packaging structure according to another embodiment of the present invention;

FIG. 5 is a schematic perspective view of a packaging structure according to another embodiment of the present invention;

Fig. 6 depicts a sectional view along line 6-6' in Fig. 5; and

FIG. 7 is a schematic cross-sectional view of a package structure according to another embodiment of the present invention.

Wherein, the reference signs are explained as follows:

100: package body

200: active components

201: First Surface

202: Second Surface

210: first electrode

211: first inner edge

221: second inner edge

220: second electrode

230: third electrode

300, 300a: the first lead frame

301, 301a: first exposed face

3011: First Bare Edge

310a: first embedded part

311a: inner end face

320a: First exposed part

400, 400a: second lead frame

401, 401a: second exposed face

4011: Second Bare Edge

410, 410a: second embedded part

411: inner end face

420, 420a: the second exposed part

500: Third lead frame

501: Third Bare Face

600, 600a: radiator

601: the first heat conducting surface

602, 602a: the second heat conducting surface

710, 720: adhesive layer

A: Arrangement direction

D1, D2: the shortest distance

L1: first embedding length

L2: Second buried length

L3: first overlap length

L4: second overlap length

O1: first overlapping area

O2: second overlap area

P1, P2: orthographic projection

detailed description

A number of embodiments of the present invention will be disclosed below with the accompanying drawings. For the sake of clarity, many practical details will be described together in the following description. However, those skilled in the art should appreciate that in some embodiments of the present invention, these practical details are not necessary and thus should not be used to limit the present invention. In addition, for the sake of simplifying the drawings, some conventional structures and components will be shown in a simple and schematic manner in the drawings.

FIG. 1 is a schematic perspective view of a packaging structure according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view along line 2-2' in Fig. 1 . As shown in FIG. 1 and FIG. 2 , in this embodiment, the package structure includes a package body 100 , an active device 200 , a first lead frame 300 and a second lead frame 400 . The active device 200 is packaged in the package body 100 and can be protected by the package body 100 . The active device 200 includes a first electrode 210 and a second electrode 220 . The first electrode 210 is disposed on the first lead frame 300 and electrically connected to the first lead frame 300 . The second electrode 220 is disposed on the second lead frame 400 and electrically connected to the second lead frame 400 . The first lead frame 300 has a first exposed surface 301 . The first exposed surface 301 and the first electrode 210 are respectively located on opposite sides of the first lead frame 300 . In other words, the first exposed surface 301 faces away from the first electrode 210 . The second lead frame 400 has a second exposed surface 401 . The second exposed surface 401 and the second electrode 220 are respectively located on opposite sides of the second lead frame 400 . In other words, the second exposed surface 401 faces away from the second electrode 220 . Both the first exposed surface 301 and the second exposed surface 401 are exposed outside the package body 100 . In this way, when the active device 200 is working, the heat generated by the first electrode 210 can be conducted to the first exposed surface 301 through the first lead frame 300, and dissipated to the external environment (such as similarly, the heat generated by the second electrode 220 can be conducted to the second exposed surface 401 through the second lead frame 400 , and dissipated to the external environment (such as air) through the second exposed surface 401 .

As shown in FIG. 2 , the first electrode 210 to the second electrode 220 define the shortest distance D1 , and the first exposed surface 301 to the second exposed surface 401 define the shortest distance D2 , wherein the shortest distance D1 is smaller than the shortest distance D2 . In this way, when the first electrode 210 and/or the second electrode 220 are transmitting high-power signals, even though the first exposed surface 301 and the second exposed surface 401 may generate arcs because they are exposed outside the package body 100 , due to the second The shortest distance D2 from the first exposed surface 301 to the second exposed surface 401 is sufficiently long, so that arc generation can be effectively prevented, thereby further avoiding the short circuit between the first electrode 210 and the second electrode 220 . Therefore, in this embodiment, the effects of heat dissipation and short-circuit prevention can be taken into account.

In some embodiments, the active device 200 includes a first surface 201 and a second surface 202 opposite to each other. In other words, the first surface 201 and the second surface 202 are located on opposite sides of the active device 200 . The first electrode 210 and the second electrode 220 are located on the first surface 201 . In other words, the first electrode 210 and the second electrode 220 are located on the same surface of the active device 200 . The first electrode 210 has a first inner edge 211 closest to the second electrode 220 . The second electrode 220 has a second inner edge 221 closest to the first electrode 210 . The first electrodes 210 and the second electrodes 220 are arranged along the arrangement direction A on the first surface 201 . The shortest distance D1 may be the distance measured along the arrangement direction A from the first inner edge 211 to the second inner edge 221 . The first exposed surface 301 has a first exposed edge 3011 closest to the second exposed surface 401 . The second exposed surface 401 has a second exposed edge 4011 closest to the first exposed surface 301 . The shortest distance D2 may be the distance measured along the arrangement direction A from the first exposed edge 3011 to the second exposed edge 4011 .

In some implementations, as shown in FIG. 2 , the orthographic projection P1 of the first electrode 210 toward the first lead frame 300 overlaps the first exposed surface 301 . In other words, as shown in FIG. 2 , a part of the first exposed surface 301 is located directly below the first electrode 210 . In this way, the heat conduction path from the first electrode 210 to the first exposed surface 301 can be shortened, so that the heat of the first electrode 210 can be transferred downward to the first exposed surface 301, thereby lifting the first lead frame 300 to the first electrode. 210 cooling effect. For example, in some implementations, as shown in FIG. 2 , the orthographic projection P1 of the first electrode 210 toward the first lead frame 300 can completely overlap the first exposed surface 301 . In other words, the orthographic projection P1 of the first electrode 210 toward the first lead frame 300 may be completely located within the first exposed surface 301 . In this way, the entire first electrode 210 is located directly above the first exposed surface 301, so the heat generated at any position of the first electrode 210 can be transferred downward to the first exposed surface 301, thereby lifting the first lead frame 300 to The heat dissipation effect of the first electrode 210 .

In some implementations, as shown in FIG. 2 , the orthographic projection P2 of the second electrode 220 toward the second lead frame 400 does not overlap the second exposed surface 401 . Such a design can preferably maintain the relationship that the shortest distance D2 is greater than the shortest distance D1 when the orthographic projection P1 of the first electrode 210 toward the first lead frame 300 overlaps the first exposed surface 301, so as to help prevent the first lead An arc is generated between the frame 300 and the second lead frame 400 to cause a short circuit between the first electrode 210 and the second electrode 220 .

In some embodiments, since the orthographic projection P2 of the second electrode 220 toward the second lead frame 400 does not overlap the second exposed surface 401 , and the orthographic projection P1 of the first electrode 210 toward the first lead frame 300 overlaps the first exposed surface 301 , so the heat dissipation effect of the second lead frame 400 on the second electrode 220 may be lower than the heat dissipation effect of the first lead frame 300 on the first electrode 210, therefore, in some embodiments, the relatively high temperature of the active element 200 can be The electrode is used as the first electrode 210 , and the relatively low-temperature electrode in the active device 200 is used as the second electrode 220 . For example, the active device 200 can be a metal-oxide-semiconductor field-effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor; MOSFET). When the MOSFET works, the temperature of the drain will be higher than the temperature of the source. Therefore, the second One electrode 210 can be a drain and the second electrode 220 can be a source, so the relatively high-temperature drain can be arranged on the first lead frame 300 with a high heat dissipation effect, and the relatively low-temperature source can be arranged on the first lead frame 300 with a relatively low heat dissipation effect. on the lower second lead frame 400 . It should be understood that the above-mentioned MOSFETs are only used for illustration, rather than limiting the active device 200 described in the present invention. In other implementations, the active device 200 can also be other devices, such as: junction field effect transistor (JFET), fin Type Field Effect Transistor (FinFET), or Insulated Gate Bipolar Transistor (IGBT), etc., but the present invention is not limited thereto.

In some implementations, as shown in FIG. 1 , the packaging structure may further include a third lead frame 500 , and the active device 200 may further include a third electrode 230 . The third electrode 230 is located on the first surface 201 of the active device 200 . In other words, the first electrode 210 , the second electrode 220 and the third electrode 230 may be located on the same surface of the active device 200 . The third electrode 230 is disposed on the third lead frame 500 and electrically connected to the third lead frame 500 . In this way, the third electrode 230 can achieve the effects of heat dissipation and signal transmission through the third lead frame 500 . For example, the active device 200 can be a transistor, and the first electrode 210 can be the drain of the transistor; the second electrode 220 can be the source of the transistor; and the third electrode 230 can be the gate of the transistor.

In some embodiments, the material of the first lead frame 300 , the second lead frame 400 and the third lead frame 500 can be a conductive material to electrically connect the corresponding electrodes. For example, the conductive material can be metal, but The present invention is not limited thereto. The first lead frame 300 , the second lead frame 400 and the third lead frame 500 are separated from each other to prevent the three from being electrically connected. For example, part of the package body 100 can be filled in the gap between the first lead frame 300 , the second lead frame 400 and the third lead frame 500 to separate the three. In some embodiments, the material of the package body 100 can be an insulating adhesive material, such as polymer adhesive material, but the present invention is not limited thereto. The insulating adhesive material can prevent the first lead frame 300 and the second lead frame 400 from It is electrically connected with the third lead frame 500 .

In some implementations, a conductive glue (not shown in the figure) may be sandwiched between the first electrode 210 and the first lead frame 300, therefore, the first electrode 210 may be fixed to the first lead frame 300 by the conductive glue and electrical connection. Similarly, in some embodiments, conductive glue may be interposed between the second electrode 220 and the second lead frame 400 , so that the second electrode 220 may be fixed and electrically connected to the second lead frame 400 by the conductive glue. Similarly, in some embodiments, conductive glue may be sandwiched between the third electrode 230 and the third lead frame 500 , so that the third electrode 230 may be fixed and electrically connected to the third lead frame 500 through the conductive glue. It should be understood that the above-mentioned conductive glue is only used to illustrate the connection method between the electrode and the lead frame, and is not intended to limit the present invention. In other embodiments, different connection methods can also be used to connect the electrode and the lead frame, for example: solder can be used To connect the electrode and the lead frame, but the present invention is not limited thereto.

FIG. 3 is a schematic cross-sectional view of a package structure according to another embodiment of the present invention. As shown in FIG. 3 , the main difference between this embodiment and the embodiment shown in FIG. 2 is that the first lead frame 300 a is different from the aforementioned first lead frame 300 . Specifically, the first lead frame 300a includes a first embedded portion 310a and a first exposed portion 320a. The first embedded portion 310 a and the first exposed portion 320 a are arranged along the arrangement direction A of the first electrode 210 and the second electrode 220 , and the first embedded portion 310 a is closer to the second electrode 220 than the first exposed portion 320 a. The first embedding portion 310 a is embedded in the package body 100 without being exposed outside the package body 100 . The first exposed surface 301 a is located at the first exposed portion 320 a and is exposed outside the package body 100 .

The first electrode 210 is disposed on the first buried portion 310a and the first exposed portion 320a. In other words, the orthographic projection P1 of the first electrode 210 toward the first lead frame 300a will overlap the first embedded portion 310a and the first exposed portion 320a. In other words, the orthographic projection P1 of the first electrode 210 toward the first lead frame 300a is not completely located within the first exposed surface 301a. Since the orthographic projection P1 of the first electrode 210 toward the first lead frame 300a overlaps the first embedding portion 310a, and the first embedding portion 310a is embedded in the package body 100, the orthographic projection of the first electrode 210 toward the first lead frame 300a P1 overlaps part of the package body 100 , that is, part of the package body 100 is located directly below the first electrode 210 , and more specifically, the first embedded portion 310 a is located between the part of the package body 100 and the first electrode 210 . Such a design can help the package body 100 to fix the first lead frame 300a more firmly.

In some implementations, as shown in FIG. 3 , the second lead frame 400 includes a second buried portion 410 and a second exposed portion 420 . The second buried part 410 and the second exposed part 420 are arranged along the arrangement direction A of the first electrode 210 and the second electrode 220 , and the second buried part 410 is closer to the first electrode 210 than the second exposed part 420 . The second embedded portion 410 is embedded in the package body 100 without being exposed outside the package body 100 . The second exposed surface 401 is located at the second exposed portion 420 and is exposed outside the package body 100 . The second electrode 220 is disposed on the second buried portion 410 . In other words, the orthographic projection P2 of the second electrode 220 toward the second lead frame 400 overlaps the second buried portion 410 and does not overlap the second exposed portion 420 . In this way, the second electrode 220 is completely disposed on the second embedded portion 410 . Since the second embedding portion 410 is embedded in the package body 100 , the orthographic projection P2 of the second electrode 220 toward the second lead frame 400 will overlap part of the package body 100 , that is, part of the package body 100 is located on the front side of the second electrode 220 . Below, more specifically, the second embedded portion 410 is located between the part of the package body 100 and the second electrode 220 . Such a design can help the package body 100 to fix the second lead frame 400 more firmly.

In some embodiments, as shown in FIG. 3 , the first buried portion 310a has a first buried length L1 parallel to the arrangement direction A of the first electrode 210 and the second electrode 220, and the second buried portion 410 also has a length parallel to the arrangement direction A of the first electrode 210 and the second electrode 220. The second buried length L2 in the alignment direction A. The first buried length L1 is smaller than the second buried length L2. In other words, in the dimension parallel to the arrangement direction A, the first embedded portion 310a is shorter than the second embedded portion 410, which can facilitate the shortest distance between the first exposed surface 301a and the first inner edge 211 along the arrangement direction A. The distance is less than the shortest distance from the second exposed surface 401 to the second inner edge 221 along the arrangement direction A, so that the heat dissipation effect of the first lead frame 300a is higher than that of the second lead frame 400, so that the relatively easy-to-heat drain The electrode is arranged on the first lead frame 300 a, and the source electrode which is relatively less prone to heat is arranged on the second lead frame 400 .

For example, the first embedding portion 310 a has an inner end surface 311 a closest to the second embedding portion 410 , and the second embedding portion 410 has an inner end surface 411 closest to the first embedding portion 310 a. In some embodiments, the inner end surface 311a of the first buried portion 310a can be substantially aligned with the first inner edge 211 of the first electrode 210, so the shortest distance from the first exposed surface 301a to the first inner edge 211 along the arrangement direction A The distance is the first embedding length L1 of the first embedding portion 310a. Similarly, in some embodiments, the inner end surface 411 of the second buried portion 410 and the second inner edge 221 of the second electrode 220 can be substantially aligned, so that the second exposed surface 401 to the second inner edge 221 are along the alignment direction The shortest distance of A is the second embedding length L2 of the second embedding portion 410 . Since the first buried length L1 is less than the second buried length L2, the shortest distance from the first exposed surface 301a to the first inner edge 211 along the arrangement direction A is shorter than the shortest distance from the second exposed surface 401 to the second inner edge 221 along the The shortest distance in the arrangement direction A is to facilitate the heat dissipation effect of the first lead frame 300 a to be higher than the heat dissipation effect of the second lead frame 400 .

In some embodiments, as shown in FIG. 3 , the orthographic projection P1 of the first electrode 210 toward the first lead frame 300 a and the first exposed surface 301 a define a first overlapping region O1 . The first overlapping region O1 has a first overlapping length L3 parallel to the arrangement direction A of the first electrodes 210 and the second electrodes 220 . Preferably, the ratio of the first overlapping length L3 to the first embedding length L1 is greater than 3, so as to facilitate the heat dissipation of the first electrode 210 by the first lead frame 300a.

Other features shown in FIG. 3 are similar to those in FIG. 1 and FIG. 2 , so reference can be made to the corresponding descriptions above without repeating the descriptions.

FIG. 4 is a schematic cross-sectional view of a package structure according to another embodiment of the present invention. As shown in FIG. 4 , the main difference between this embodiment and the embodiment shown in FIG. 3 is that the orthographic projection P2 of the second electrode 220 toward the second lead frame 400 a overlaps the second exposed surface 401 a. In other words, part of the second exposed surface 401 a is located under the second electrode 220 . In this way, the heat conduction path from the second electrode 220 to the second exposed surface 401a can be shortened, so that the heat of the second electrode 220 can be transferred downward to the second exposed surface 401a, thereby lifting the second lead frame 400a to the second electrode. 220 cooling effect. Specifically, the second electrode 220 is disposed on the second buried portion 410a and the second exposed portion 420a. In other words, the orthographic projection P2 of the second electrode 220 toward the second lead frame 400a not only overlaps the second embedded portion 410 but also overlaps the second exposed surface 401a on the second exposed portion 420a to facilitate heat dissipation.

In some embodiments, as shown in FIG. 4 , the orthographic projection P2 of the second electrode 220 toward the second lead frame 400 a and the second exposed surface 401 a define a second overlapping region O2 . The second overlapping region O2 has a second overlapping length L4 parallel to the arrangement direction A of the first electrodes 210 and the second electrodes 220 . The first overlapping length L3 of the first overlapping area O1 is greater than the second overlapping length L4 of the second overlapping area O2. In other words, the overlapping area of the first exposed surface 301a and the first electrode 210 is greater than the overlapping area of the second exposed surface 401a and the second electrode 220, so that the heat dissipation effect of the first lead frame 300a on the first electrode 210 is higher than that of the second exposed surface 401a. The heat dissipation effect of the second lead frame 400 a on the second electrode 220 .

Other features shown in FIG. 4 are similar to those in FIG. 1 to FIG. 3 , so reference can be made to the corresponding description above, and the description will not be repeated.

FIG. 5 is a schematic perspective view of a packaging structure according to another embodiment of the present invention. Fig. 6 shows a cross-sectional view along line 6-6' in Fig. 5 . As shown in FIG. 5 and FIG. 6 , the main difference between this embodiment and the previous embodiments is that: in this embodiment, the packaging structure further includes a heat sink 600 . The heat sink 600 connects the second surface 202 of the active device 200 and the third lead frame 500 . In this way, the heat of the active device 200 can not only be conducted to the first lead frame 300 and the second lead frame 400 through the first electrode 210 and the second electrode 220 on the first surface 201 , but also through the second surface 202 The heat sink 600 on the top is conducted to the third lead frame 500 .

Further, as shown in FIG. 6 , the heat sink 600 includes a first heat conduction surface 601 and a second heat conduction surface 602 opposite to each other. The first heat conducting surface 601 faces the active device 200 and the third lead frame 500 and is disposed on the active device 200 and the third lead frame 500 . For example, the package structure may further include adhesive layers 710 and 720 . The adhesive layer 710 is adhered between the first heat conducting surface 601 and the second surface 202 of the active device 200 . The adhesive layer 720 is adhered between the first heat conducting surface 601 and the third lead frame 500 . In this way, the heat on the second surface 202 of the active device 200 can be conducted to the third lead frame 500 through the heat sink 600 . In some embodiments, the third lead frame 500 has a third exposed surface 501 . The third exposed surface 501 is exposed outside the package body 100 . In this way, the heat conducted from the active device 200 to the third lead frame 500 can be dissipated into the external environment (such as air) through the third exposed surface 501 .

Other features shown in FIG. 5 and FIG. 6 are similar to those in FIG. 1 to FIG. 4 , so reference can be made to the corresponding description above, and the description will not be repeated.

FIG. 7 is a schematic cross-sectional view of a package structure according to another embodiment of the present invention. As shown in FIG. 7 , the main difference between this embodiment and the embodiment shown in FIG. 6 is that: the second heat conducting surface 602 a of the heat sink 600 a is exposed outside the package 100 . In this way, the heat transferred from the active component 200 to the heat sink 600 a can not only be transferred to the third lead frame 500 , but also be dissipated into the external environment (such as air) through the second heat transfer surface 602 . Other features shown in FIG. 7 are similar to those in FIG. 1 to FIG. 6 , so reference can be made to the corresponding description above, and the description will not be repeated.

Although the present invention has been disclosed above in terms of implementation, it is not intended to limit the present invention. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall prevail as defined by the appended claims.

Claims (10)

1. A packaging structure, comprising: a package; An active element packaged in the package, the active element including a first electrode and a second electrode; A first lead frame, the first electrode is arranged on the first lead frame and electrically connected to the first lead frame, the first lead frame has a first exposed surface, the first exposed surface and the first exposed surface The electrodes are respectively located on opposite sides of the first lead frame, and the first exposed surface is exposed outside the package; and A second lead frame, the second electrode is arranged on the second lead frame and electrically connected to the second lead frame, the second lead frame has a second exposed surface, the second exposed surface and the second exposed surface The electrodes are respectively located on opposite sides of the second lead frame, and the second exposed surface is exposed outside the package; Wherein the shortest distance from the first electrode to the second electrode is smaller than the shortest distance from the first exposed surface to the second exposed surface. 2. The package structure of claim 1, wherein an orthographic projection of the first electrode toward the first lead frame overlaps the first exposed surface. 3. The package structure of claim 1, wherein an orthographic projection of the second electrode toward the second lead frame does not overlap the second exposed surface. 4. The package structure according to claim 1, wherein an orthographic projection of the first electrode toward the first lead frame and the first exposed surface define a first overlapping area, and the second electrode toward the second lead frame The orthographic projection and the second exposed surface define a second overlapping area, the first electrode and the second electrode are arranged along an alignment direction, the first overlapping area has a first overlapping length parallel to the alignment direction, The second overlapping region has a second overlapping length parallel to the arrangement direction, and the first overlapping length is greater than the second overlapping length. 5. The package structure according to claim 1, wherein the first electrode has a first inner edge closest to the second electrode, the second electrode has a second inner edge closest to the first electrode, the The first electrode and the second electrode are arranged along an arrangement direction, and the shortest distance from the first exposed surface to the first inner edge along the arrangement direction is smaller than the distance from the second exposed surface to the second inner edge along the arrangement direction. The shortest distance in the alignment direction. 6. The package structure according to claim 1, wherein the first lead frame comprises a first embedded portion and a first exposed portion, the first electrode and the second electrode are arranged along an arrangement direction, the first An embedded portion and the first exposed portion are arranged along the arrangement direction, and the first embedded portion is closer to the second electrode than the first exposed portion, and the first electrode overlaps with the orthographic projection of the first lead frame The first embedded portion and the first exposed portion, the first embedded portion is embedded in the package, and the first exposed surface is located at the first exposed portion. 7. The package structure according to claim 6, wherein the second lead frame comprises a second embedded portion and a second exposed portion, the second embedded portion and the second exposed portion are arranged along the alignment direction, and the second embedded portion is closer to the first electrode than the second exposed portion, the second electrode overlaps the second embedded portion toward the orthographic projection of the second lead frame, and the second embedded portion is embedded in the package, The second exposed surface is located at the second exposed portion, wherein the first buried portion has a first buried length parallel to the alignment direction, and the second buried portion has a second buried length parallel to the aligned direction , the first buried length is smaller than the second buried length. 8. The package structure of claim 1, wherein the first electrode is a drain, and the second electrode is a source. 9. The package structure according to claim 1, further comprising a heat sink and a third lead frame, wherein the active device comprises a third electrode and a first surface and a second surface opposite, the first electrode , the second electrode and the third electrode are located on the first surface, the third electrode is disposed on the third lead frame, and the heat sink is connected to the second surface of the active element and the third lead frame. 10. The package structure according to claim 9, wherein the heat sink has a first heat conduction surface and a second heat conduction surface opposite, the first heat conduction surface faces the active element, and the second heat conduction surface is exposed on the package in vitro.