CN1893061A - Package structure of power supply module - Google Patents

Abstract

A packaging structure of a power supply module, in which a control circuit is manufactured on a circuit board instead of directly on a substrate, which can reduce the occupied substrate area and save manufacturing costs, and a power element is arranged on a material with high heat transfer properties, so that the heat generated by the power element can be quickly transferred and dissipated, thereby improving the reliability of the power supply module.

Description

Package structure of power supply module

technical field

The present invention relates to a packaging structure of a power supply module, in particular to a packaging structure of a power supply module featuring high heat dissipation and high density.

Background technique

The reduction in size and the increasing complexity of design are the common trends of various electronic products. Therefore, in addition to the reduction in the size of electronic components, how to arrange the most components and wires in a limited space has become an important issue for semiconductor packaging. However, under the packaging structure with higher and higher density of components and wires, the high-density components driving the packaging structure will generate a lot of heat. Especially for power modules, this large amount of heat will affect the life and operation of electronic products. Therefore, how to solve the heat dissipation problem of this high-density packaging structure has also become an important issue.

Referring to FIG. 1 , it is a schematic cross-sectional view of a known package structure of a power module. It includes a high heat dissipation substrate 100 made of a polymer insulating layer and a metal aluminum foil layer, and the circuit (not shown in the figure) of the power supply module is completely fabricated on the substrate 100 . The power element 110a, the control element 110b and other elements 110c of the power supply module are all arranged on the substrate. In addition, there are leadframes (leadframe) 121, 122 above the substrate 100, and the wire bonding method is used, that is, through a plurality of wires 111 , 112 , 113 are electrically connected to the components 110 a , 110 b , 110 c ; The components and circuits on the substrate 100 and the lead frames 121 , 122 of the power module are sealed by potting or molding methods, so that only the pins of the lead frames are exposed. This packaging structure of the power supply module has the advantage of being easy to manufacture because of its simple structure. However, all the components 110a, 110b, 110c and circuits are arranged on the substrate 100. Therefore, the circuit density of the power supply module cannot be increased, and a substrate with a larger area is required, resulting in a relatively higher cost. The heat generated by the power components 110a, 110b, and 110c in the power supply module is transmitted to the heat dissipation element (heat sink) connected outside the substrate 100 via the substrate 100, but the heat sink between the substrate 100 and the heat dissipation element is transmitted by thermal paste. Therefore, although the substrate 100 is a material with high heat dissipation, it still cannot have an instant and large amount of good heat transfer function.

Referring to FIG. 2 , it is a schematic cross-sectional view of another known packaging structure of a power supply module. The packaging structure of the power module shown in it is similar to that shown in Figure 1, which also includes a substrate 100 with all circuits and high heat dissipation that is composed of a polymer insulating layer and a metal aluminum foil layer, and a power element 110a and a control element are also arranged on it. 110b and other components 110c, and there are lead frames 121, 122 above the substrate 100, and a plurality of wires 111, 112, 113 are formed to electrically connect the components 110a, 110b, 110c by wire bonding; the lead frames 121, 122 and the surface circuit on the substrate 100. The components and circuits on the substrate 100 and the lead frames 121 , 122 of the power supply module are sealed by potting or molding, so that only the pins of the lead frames are exposed. But the power module is different from FIG. 1 in that it is connected to a metal plate 200 on the bottom surface of the substrate 100 . This power module packaging structure also has the advantage of being easy to manufacture because of its simple structure, and has a metal plate 200, and thus the high thermal conductivity of the metal plate 200 can provide good instantaneous and large heat transfer functions. However, all components 110a, 110b, 110c and circuits are also disposed on the substrate 100. Therefore, this power supply module also has problems such as that the circuit density cannot be increased, and the cost is increased.

Referring to FIG. 3 , it is a schematic cross-sectional view of another known package structure of a power module. It includes a high heat dissipation substrate 100 made of a polymer insulating layer and a metal aluminum foil layer, and the package structure is different from that shown in FIG. 1 and FIG. 2 . The power element 110a and the control element 110b of the power supply module are all mounted on the lead frame 121, 122 by direct welding or other methods, and the lead frame 121, 122 is above the substrate 100 and the two are not connected. In addition, wire bonding is used, that is, a plurality of wires 111, 112 . The components and circuits on the substrate 100 and the lead frames 121 and 122 of the power supply module are sealed by potting or molding, so that only the pins of the lead frames are exposed. This power module packaging structure has the advantage of being easy to manufacture because of its simple structure. However, since the lead frame is integrated with the entire circuit layout of the power supply module, the density and precision of the circuit and packaging structure are limited. The heat generated by the power element 110a in the power supply module is transmitted to the substrate 100 through the lead frame and the encapsulation material, but the heat is transferred between the substrate 100 and the heat dissipating element through thermal grease, so the heat conduction effect is not good.

Therefore, how to increase the density of the packaging structure to save costs is an important issue, and while increasing the density of the packaging structure, how to solve the heat dissipation problem caused by the high-density packaging structure and power components is also another important issue.

Contents of the invention

In view of the problems of poor circuit density and heat dissipation efficiency of the packaging structure in the above technical background, the present invention discloses a packaging structure in which the circuit is fabricated on the circuit board and stacked with the lead frame, and the power supply element has a good heat conduction path , so as to improve the problems of poor heat dissipation and circuit density that cannot be improved due to poor packaging structure in the known technology.

The purpose of the present invention is to replace the arrangement of circuits on the substrate by a circuit plate, and the circuit boards are stacked to form a stacked structure on some lead frames, so there is no circuit layout or circuit board on the substrate, which can improve its performance. Circuit density and shrink packaging structure. Therefore, the required substrate area can be reduced, and the relative cost will also be reduced.

The purpose of the present invention is to set the power element on the high heat dissipation material on the substrate or directly on a substrate with high heat dissipation characteristics, so that the large amount of heat generated by the power element during operation can be quickly It conducts to the substrate and dissipates to the outside, without the need for packaging materials with poor thermal conductivity, and its heat conduction efficiency is excellent. Because of its good heat conduction efficiency, it can withstand the high heat generated by the passage of instantaneous large current, so as to avoid the damage of the power supply module caused by the high heat that cannot be quickly conducted and dissipated.

According to the above purpose, the present invention provides a packaging structure of a power supply module with high density and high heat dissipation. It includes a substrate with high heat dissipation characteristics, and a lead frame is arranged on the front surface of the substrate. A circuit plate with the circuit layout of the power supply is arranged on some lead frames to form a stacked structure. And several (or only one) control components are set on the circuit board, and several power components are set on the high heat dissipation material on the substrate, such as lead frame or metal block, or directly set on this high heat dissipation characteristic A good thermal conduction path is formed on the substrate. And there are several wires connecting the circuit board and the lead frame, the circuit board and the first component, and the first component and the lead frame. A sealant seals part of the substrate, components on the substrate, lead frame, circuit board, etc.

Therefore, through the above packaging structure, since the circuit is disposed on the circuit board instead of directly on the substrate, and forms a stacked structure with the lead frame and the substrate, the required substrate area is reduced, and the packaging volume can be effectively reduced. Moreover, the power supply element is arranged on the high heat dissipation substrate or the high heat dissipation material on the substrate, forming a good heat conduction path, which can effectively and quickly conduct a large amount of heat generated by the power supply element to the outside or heat dissipation device.

Description of drawings

1 to 3 are respectively schematic cross-sectional views of packaging structures of power resistors in three known technologies.

4A and 4B are schematic cross-sectional views of a packaging structure of a power resistor according to an embodiment of the present invention, and the circuit board and various components are all arranged on the lead frame.

5A to 5C are embodiments of the lead frame of the present invention on the same plane and different planes, respectively.

FIG. 7 is a schematic cross-sectional view of a package structure of a power resistor according to an embodiment of the present invention, the power element of which is directly disposed on the front surface of the substrate.

8 is a schematic cross-sectional view of a packaging structure of a power resistor according to an embodiment of the present invention, the power element of which is disposed on a metal block and connected to the substrate.

Explanation of symbols in the figure:

400 substrates

410a power components

410b control element

411, 412, 413, 414, 415, 416 wires

417 Adhesive

420 lead frame

420a first surface

420b second surface

421, 422 pins

423a Lead frame with both sides on the same plane

423b Lead frame with downward slope on both sides

423c Lead frame with one side tilted up and the other side tilted down on both sides

424 Metal Block

425 circuit board

426 sealant

430 sheet metal

Detailed ways

Please refer to FIG. 4A , which is a schematic cross-sectional view of a package structure of a power supply module according to an embodiment of the present invention. The packaging structure includes a substrate 400 with high heat dissipation and insulation properties, and the substrate 400 has a front surface 400a and a back surface 400b corresponding to the front surface. A lead frame 420 with a plurality of pins 421 , 422 . A circuit plate (circuit plate) 425 is arranged on the first surface 420a of the lead frame 420 with its two ends connected to form a stacked structure and arranged on the substrate 400, so the required substrate area can be reduced and the packaging structure can be reduced. volume of. In addition, there is a second element 410b (in other embodiments, there may be a plurality of them) and a plurality of first elements 410a are respectively arranged on the circuit board 425 and the first surface 420a of the lead frame 420, and are connected by wire bonding. Several wires 411 , 412 , 413 , 414 , 415 , 416 . And seal part of the substrate, components on the substrate, lead frame (except pins), circuit board, etc. with a sealant.

In the above packaging structure, all circuit configurations are fabricated on the circuit board 425 instead of on the substrate 400 and form a stacked structure with the lead frame 420 and the substrate 400, so that the required substrate area can be reduced and the packaging can be reduced. The volume of the structure. The substrate 400 disclosed in the present invention can be made of an insulating material, such as a ceramic material; or a composite material containing metal, or a composite material containing metal on one or both sides. Furthermore, the material of the circuit board disclosed in the present invention is also an insulating material, such as glass fiber epoxy or ceramic material.

In addition, in this embodiment, the adhesive material 417 , such as silver adhesive, is used as the connection of the wire circuit board 425 , the frame 420 and the substrate 400 to form a stacked structure. However, in other embodiments of the present invention, it can also be directly connected by soldering.

The first component 410a disclosed in the present invention is a power component, which refers to a component that generates high heat when the power supply module operates. These power elements 410 a are disposed on the lead frame 420 to form a good heat conduction path, and the heat can be quickly conducted to the substrate 400 and the external heat dissipation device through the lead frame 420 to dissipate heat. In addition, as shown in FIG. 4B , a metal plate 430 can be disposed on the back surface 400 b of the substrate 400 to increase heat dissipation efficiency. As for the second element 410b being a control element, it refers to an element that controls the action of the power element. The control elements 410b are arranged on the circuit board 425, and the wires are electrically connected to the circuit on the circuit board 425 by wire bonding, and then electrically connected to the power element 410a through the wires to control the action of the power element 410a.

In addition, although the lead frame 420 is in the packaging structure disclosed in this embodiment, its two sides are upward. However, it does not mean that the lead frame structure of the present invention is limited to this structure, but may be on the same plane or on different planes. The following embodiments will disclose various lead frame structures of the present invention, but are not limited thereto. Variations can be made by those skilled in the art without departing from the scope of the invention.

Referring to FIG. 5A , the packaging structure is substantially the same as that described in the above-mentioned embodiment (see FIG. 4 ). The difference is that the lead frame 423a is on the same plane, which is a plane structure without any upward or downward tilt. Of course, the package structure as shown in Figure 5B can also be used, which is the same as Figure 4, the lead frame is located on a different plane, but the lead frame is not like the lead frame shown in Figure 4 with both sides tilted up, but the lead frame 423b has a downward sloping structure on both sides; or as shown in FIG. 5C , the lead frame 423c is located on different planes, and one side has an upward slanting structure, while the other side has a downward sloping structure. In addition, there are other variations but all are applicable according to the spirit of the present invention.

6 is a schematic cross-sectional view of another embodiment of the present invention, one has a first surface 420a and a second surface 420b, and has a plurality of pins 421, 422 (not shown in other figures). The package structure also includes a substrate 400 with high heat dissipation characteristics, a front side 400 a and a back side 400 b corresponding to the front side, and a circuit board 425 . A part of the lead frame 420 is connected to the circuit board 425 through the second surface 420b to form a stacked structure, and another part is connected to the front surface 400a of the substrate 400 through the second surface 420b to be disposed thereon. The stacked structure formed by the circuit board 425 and the lead frame 420 is disposed on a metal plate 430 , and the substrate 400 is connected to the metal plate with a back surface 400 b and disposed thereon. A second element 410b, that is, a control element (in other embodiments, there may be a plurality of them) and a plurality of first elements 410a, that is, a power supply element are respectively arranged on the circuit board 425 and on the first surface 420a of the lead frame 420, and are formed by printing In the wire bonding method, several wires 411, 412, 413, 414, 415, 416, . And seal part of the substrate, components on the substrate, lead frame (except pins), circuit board, etc. with a sealant.

In this embodiment, all the circuit configurations are also fabricated on the circuit board 425 instead of on the substrate 400, and form a stacked structure with the lead frame 420, so the required substrate area can be reduced and the volume of the packaging structure can be reduced. . The power supply element 410 a is disposed on the lead frame 420 , and the heat is dissipated to the outside or heat dissipation device through the substrate 400 and the metal plate 430 through the good heat conduction characteristic of the lead frame 420 . Of course, the lead frames in this embodiment may also be on the same plane as in the foregoing embodiments, or on different planes.

Referring to FIG. 7 , it is a schematic cross-sectional view of a packaging structure of a power supply module according to another embodiment of the present invention. The packaging mechanism includes a lead frame 420 having a first surface 420 a and a second surface 420 b, and at least one lead, such as 421 , 422 and so on. A circuit board 425 is connected to the first surface 420a of a part of the lead frame 420 and disposed thereon to form a stack structure, and in other embodiments, the stack structure may also be a circuit board 425 and the second surface 420b of a part of the lead frame 420 connected. A substrate 400 with high heat dissipation characteristics and a front surface 400a and a rear surface 400b corresponding to the front surface, and another part of the lead frame 420 is arranged on the substrate 400 by connecting the second surface 420b to the front surface 400b of the substrate 400 . A second element 410b, that is, a control element (in other embodiments, there may be a plurality of them) is arranged on the circuit board 425, and a plurality of first elements 410a, that is, a power element, are directly arranged on the front surface 400a of the substrate 400, and are wired together. The bonding method uses several wires 411 , 412 , 413 , 414 , 415 , 416 . And seal part of the substrate, components on the substrate, lead frame (except pins), circuit board, etc. with a sealant.

In this embodiment, all circuit configurations are also fabricated on the circuit board 425 instead of on the substrate 400 and form a stacked structure with the lead frame 420 and the substrate 400, so the required substrate area can be reduced and the package structure can be reduced. volume of. The power supply element 410 a is directly disposed on the substrate 400 and dissipates heat to the outside or a heat dissipation device through the good thermal conductivity of the substrate 400 . Of course, the lead frames in this embodiment may also be on the same plane as in the foregoing embodiments, or on different planes.

Referring to FIG. 8 , it is a schematic cross-sectional view of a packaging structure of a power supply module according to another embodiment of the present invention. The packaging structure includes a substrate 400 with high heat dissipation and insulation properties, and the substrate 400 has a front surface 400a and a back surface 400b corresponding to the front surface. A lead frame 420 with a plurality of pins 421 , 422 . Secondly, there are a plurality of high heat dissipation material blocks 424 disposed on the front surface 400 a of the substrate 400 . One end of a circuit plate (circuit plate) 425 is connected to the first surface 420a of the lead frame 420 and arranged on it to form a stacked structure, and the other end is connected to the nearest high heat dissipation material block 424 and arranged on it, so the required occupation can be reduced. Substrate area, reducing the volume of the packaging structure. In addition, a plurality of control elements 410b and a plurality of power elements 410a are respectively arranged on the circuit board 425 and the high heat dissipation material block 424, and several wires 412, 413, 414, 415, 416... The power element 410a, the circuit on the circuit board 425 (not shown in the figure), and the lead frame 420 are electrically connected. In addition, a metal plate 430 is connected to the back surface 400b of the substrate 400 (the metal plate may not be required in other embodiments). Part of the substrate 400 , components on the substrate, lead frame 420 (except pins), circuit board 425 , etc. are sealed with a sealant.

The package structure disclosed above (shown in FIG. 8 ) uses the same substrate 400 and circuit board 425 as the other embodiments mentioned above. The circuit board 425 and the lead frame 420 form a stacked structure and are disposed on the substrate 400 . Since they are stacked, the occupied substrate area can also be reduced to achieve the effect of reducing the volume of the packaging structure.

Furthermore, the power element 410 a is disposed on the high heat dissipation material block 424 on the substrate 400 , and the back surface 400 b of the substrate 400 is connected to a metal plate. Therefore, a large amount of heat generated by the operation of the power element 410a is quickly conducted to the substrate 400 and the metal plate 430 through the high heat dissipation material block 424, and the heat is dissipated to the outside or an external heat sink (not shown) through the metal plate. Therefore, the packaging structure can further withstand a large amount of heat generated by passing a large current instantaneously. The high heat dissipation material block 424 is usually a metal block.

Secondly, in other embodiments, the control element 410b may also be electrically connected to the circuit board 425 directly instead of through wire bonding. The circuit board 425 and the lead frame 420 are electrically connected by an adhesive material 417 to receive wires, and the adhesive material 417 is usually a conductive material, such as silver glue. Of course, the lead frames of this packaging structure can also be on the same plane or on different planes as required in other embodiments described above.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Changes can still be made and implemented within the scope of not departing from the essence of the present invention, and these changes should still belong to the scope of the present invention. Therefore, the scope of the present invention is defined by the following patent claims.

Claims (10)

1. A package structure of a power supply module, characterized in that it comprises: A lead frame has a first surface and a second surface corresponding to the first surface, and has at least one pin; a circuit board connected to part of the lead frame to form a stacked structure; a substrate having a front side and a back side, part of the lead frame is disposed on the front side with the second surface; At least one first element is disposed on the substrate; at least one second component disposed on the circuit board; and A plurality of wires connect the circuit board and the lead frame, the circuit board and the first component, and the first component and the lead frame. 2. The power module packaging structure according to claim 2, wherein the substrate is an insulating material, and the insulating material is selected from a composite system containing metal on one side and a composite system containing metal on both sides. Composite systems consisting of metals in groups. 3. The packaging structure of the power supply module as claimed in claim 1, wherein the circuit board is an insulating material selected from the group consisting of epoxy fiberglass material and ceramics. 4. The power module package structure according to claim 1, wherein the first component and the second component are a power component and a control component respectively. 5 . The packaging structure of the power supply module according to claim 1 , wherein the circuit board is connected to a part of the first surface of the lead frame and disposed thereon to form the stacked structure. 6 . 6 . The power module packaging structure according to claim 1 , wherein the circuit board is connected to a part of the second surface of the lead frame and disposed thereon to form the stacked structure. 7. The power module package structure according to claim 1, wherein the stack structure is disposed on the front surface of the substrate. 8. The packaging structure of the power supply module according to claim 1, further comprising a metal plate disposed on the back surface of the substrate. 9. The power module package structure according to claim 1, further comprising at least one metal block interposed between the first element and the substrate. 10 . The power module package structure according to claim 1 , wherein part of the lead frame is interposed between the first component and the substrate. 11 .

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