Packaging structure of high-thermal-conductivity semiconductor device

Abstract

A packaging structure of a high-thermal-conductivity semiconductor device comprises a semiconductor chip, the surface of which comprises a connecting surface; the lead frame comprises a heat dissipation piece and a plurality of pin structures, the heat dissipation piece is arranged on the connecting surface, each pin structure comprises a pin connecting part and a pin main body part, at least part of the pin connecting part is bare copper, and the pin main body part is tinned copper; the packaging structure comprises a semiconductor chip, a heat dissipation piece and a plastic packaging material, filler of the plastic packaging material at least comprises spherical silicon, the plastic packaging material wraps the periphery of the semiconductor chip and the heat dissipation piece, at least part of the heat dissipation piece is exposed, and the semiconductor chip and the heat dissipation piece are packaged together through the plastic packaging material. The pin connecting part is packaged in the plastic packaging material, and the pin main body part is exposed out of the packaging material. The packaging structure of the high-thermal-conductivity semiconductor device has the advantages of heat dissipation, manufacturability, reliability and adaptability.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a packaging structure of a high thermal conductivity semiconductor device. Background Art

[0002] When the chip is working, some of the electrical energy of the internal transistors and other components will be converted into heat energy during the process of logical operation and current control. This heat needs to be dissipated in time, otherwise it will affect the performance of the chip or even cause damage. With the rapid development of electronic technology, the performance of semiconductor devices is constantly improving, and the power density is getting higher and higher, making heat dissipation a key factor affecting the performance and reliability of semiconductor devices.

[0003] The traditional packaging method has certain limitations in heat dissipation and is difficult to meet the requirements of modern electronic equipment for efficient heat dissipation. Therefore, in the prior art, a packaging method with exposed heat sink is adopted to improve the heat dissipation efficiency.

[0004] Typically, a single crystalline molding compound is used for packaging, the purpose of which is to utilize the good thermal conductivity of the crystalline molding compound to help dissipate heat.

[0005] However, although the single crystal type plastic encapsulation material has good thermal conductivity, it is not in the heat dissipation channel of the chip, so it contributes little to the heat dissipation of the chip. In addition, the thermal expansion coefficient of the single crystal type plastic encapsulation material is often quite different from the material of the chip and the heat sink. During the temperature cycle, this difference will cause a large thermal stress to be generated at the interface of the combination, which not only reduces the heat conduction efficiency, but also easily destroys the combination of the interface, making the device reliability poor. The single crystal type plastic encapsulation material is also hesitant because its crystals are irregular and have poor fluidity. Therefore, on the one hand, it is necessary to apply a large pressure during shaping, resulting in poor process operability. On the other hand, not only is the wrapping ability of the heat sink and conductive structure of the complex structure poor, but the plastic encapsulation material during the plastic encapsulation process is difficult to enter the narrow gap between the chip and the heat sink, resulting in a decrease in the heat dissipation efficiency of the plastic encapsulation material, and its contribution to the heat dissipation of the chip is further reduced, and the adaptability to heat sinks and lead frames of different shapes and sizes is poor, and it is difficult to form a well-combined packaging structure. Therefore, the plastic encapsulation material of the existing packaging structure has a poor effect on improving the heat dissipation efficiency, and the processability, reliability and adaptability of the packaging structure are all poor. Summary of the invention

[0006] The technical problem solved by the present invention is to provide a packaging structure of a high thermal conductivity semiconductor device to take into account heat dissipation, processability, reliability and adaptability.

[0007] In order to solve the above technical problems, the technical solution of the present invention provides a packaging structure of a high thermal conductivity semiconductor device, comprising: a semiconductor chip, the surface of the semiconductor chip includes a connection surface; a lead frame, including a heat sink and a plurality of pin structures, the heat sink is arranged on the connection surface, the pin structure includes a pin connection part and a pin body part, and at least part of the pin connection part is bare copper, and the pin body part is copper tin-plated; a plastic encapsulation material, the filler of the plastic encapsulation material at least contains spherical silicon, the plastic encapsulation material is wrapped around the semiconductor chip and the heat sink, and at least part of the heat sink is exposed, so that the semiconductor chip and the heat sink are encapsulated together by the plastic encapsulation material, in addition, the pin connection part is encapsulated in the plastic encapsulation material, and the pin body part is exposed outside the encapsulation material.

[0008] Optionally, the filler also includes crystalline silicon.

[0009] Optionally, the crystalline silicon is less than the spherical silicon.

[0010] Optionally, the tin in the copper tin plating is pure tin or alloy tin.

[0011] Optionally, the wire frame is roughened.

[0012] Optionally, all the pin connecting parts are bare copper.

[0013] Optionally, some of the pin connecting parts are bare copper, and some of the pin connecting parts are silver-plated copper.

[0014] Optionally, an end of the lead body portion and the heat sink are located on the same side of the semiconductor chip.

[0015] Optionally, the ends of the lead body and the heat sink are located on two opposite sides of the semiconductor chip respectively.

[0016] Optionally, the connection surface and the heat sink are filled with thermally conductive adhesive, and the heat sink and the connection surface are connected via the thermally conductive adhesive.

[0017] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0018] In the packaging structure of the high thermal conductivity semiconductor device provided by the technical solution of the present invention, the heat sink is arranged on the connection surface of the semiconductor chip, and the heat sink is at least partially exposed, so the heat sink and the semiconductor chip together form a stable heat dissipation channel, and the heat of the semiconductor chip is efficiently transferred to the heat sink and then dissipated outward, thereby ensuring the heat dissipation. In addition, since the filler of the plastic encapsulation material at least contains spherical silicon, which is a molten filler with good fluidity, and the pin connection part is at least partially bare copper and is encapsulated in the plastic encapsulation material, and the main body of the pin is copper tin-plated and exposed outside the packaging material, therefore, the packaging structure has good processability, reliability and adaptability. Therefore, heat dissipation, processability, reliability and adaptability are taken into account. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic cross-sectional view of a packaging structure of a high thermal conductivity semiconductor device according to an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the cross-sectional structure of the packaging structure of a high thermal conductivity semiconductor device according to another embodiment of the present invention

[0021] Description of reference numerals:

[0022] 10-semiconductor chip; 11-connection surface;

[0023] 20- heat sink;

[0024] 30-molding material; 31-spherical silicon; 32-crystalline silicon;

[0025] 40-pin structure; 41-pin connection portion; 42, 43-pin main body; 420, 430-terminal end;

[0026] 50-Thermal conductive adhesive. DETAILED DESCRIPTION

[0027] As described in the background art, the plastic packaging material of the existing packaging structure has a poor effect on improving the heat dissipation efficiency, and the processability, reliability and adaptability of the packaging structure are all relatively poor.

[0028] In order to solve the above technical problems, the technical solution of the present invention provides a packaging structure of a high thermal conductivity semiconductor device, comprising: a semiconductor chip, the surface of the semiconductor chip includes a connection surface; a lead frame, including a heat sink and a plurality of pin structures, the heat sink is arranged on the connection surface, the pin structure includes a pin connection part and a pin body part, and at least part of the pin connection part is bare copper, and the pin body part is copper tin-plated; a plastic encapsulation material, the filler of the plastic encapsulation material at least contains spherical silicon, the plastic encapsulation material is wrapped around the semiconductor chip and the heat sink, and at least part of the heat sink is exposed, so that the semiconductor chip and the heat sink are packaged together by the plastic encapsulation material, in addition, the pin connection part is encapsulated in the plastic encapsulation material, and the pin body part is exposed outside the packaging material. Through the above packaging structure of the high thermal conductivity semiconductor device, heat dissipation, processability, reliability and adaptability can be taken into account.

[0029] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] Figure 1 It is a schematic cross-sectional view of a packaging structure of a high thermal conductivity semiconductor device according to an embodiment of the present invention.

[0031] Please refer to Figure 1 The packaging structure of the high thermal conductivity semiconductor device includes: a semiconductor chip 10, a plastic packaging material 30 and a lead frame.

[0032] The surface of the semiconductor chip 10 includes a connection surface 11 .

[0033] The lead frame includes: a heat sink 20 and a plurality of lead structures 40. In some embodiments, the heat sink 20 is connected to at least one lead structure 40. In other embodiments, the heat sink 20 and all the lead structures 40 are independent of each other.

[0034] The heat sink 20 is disposed on the connection surface 11. The connection surface 11 is used to define a portion of the surface of the semiconductor chip 10 for disposing the heat sink.

[0035] The pin structure 40 includes a pin connection portion 41 and a pin body portion 42. The pin connection portion 41 is encapsulated in the plastic packaging material 30, and the pin body portion 42 is exposed outside the plastic packaging material 30. At least part of the pin connection portion 41 is bare copper, and the pin body portion 42 is copper plated with tin.

[0036] The filler of the molding compound 30 at least includes spherical silicon 31 . The molding compound 30 wraps around the semiconductor chip 10 and the heat sink 20 and exposes at least a portion of the heat sink 20 , so that the semiconductor chip 10 and the heat sink 20 are packaged together by the molding compound 30 .

[0037] In the semiconductor chip 10 provided in the embodiment of the present invention, the heat sink 20 is arranged on the connection surface 11 of the semiconductor chip 10, and the heat sink 20 is at least partially exposed. Therefore, the heat sink 20 and the semiconductor chip 10 together form a stable heat dissipation channel, and the heat of the semiconductor chip 10 is efficiently transferred to the heat sink and then dissipated outward, thereby ensuring the heat dissipation.

[0038] Moreover, since the filler of the molding compound 30 contains at least spherical silicon 31, and at least part of the pin connection part 41 is bare copper and is encapsulated in the molding compound 30, and the pin main body 42 is tin-plated copper and exposed outside the packaging compound, the packaging structure has good processability, reliability and adaptability.

[0039] Specifically, the spherical silicon 31 is a molten filler with good fluidity and an expansion coefficient close to that of the semiconductor chip and the heat sink (usually metal). Therefore, on the one hand, the pressure required for shaping is small, and the process operability is good. On the other hand, the wrapping ability of the heat sink 20 and the pin connection part 41 with complex structures is good, and the plastic encapsulation material 30 in the plastic encapsulation process can easily enter the narrow gap between the chip and the heat sink 20, and the connector 41, so that a uniform and dense packaging structure can be formed for heat sinks 20 and connectors 41 of different shapes and sizes, and the interface bonding of the plastic encapsulation material 30 with the heat sink 20 and the connector 41 is stable and fit. On the third hand, under different temperature conditions, the thermal stress generated at the interface between the plastic encapsulation material 30 and the semiconductor chip 10, the heat sink 20 and the pin connection part 41 is small, and the plastic encapsulation material 30 can maintain close contact with the semiconductor chip 10, the heat sink 20 and the pin connection part 41, thereby reducing thermal resistance, improving heat dissipation efficiency, and having good reliability of interface bonding.

[0040] Moreover, at least part of the pin connection part 41 is bare copper and is encapsulated in the plastic encapsulation material 30, so it is also beneficial to strengthen the bonding stability and bonding strength between the plastic encapsulation material 30 and the lead frame. Specifically, on the one hand, the surface energy of copper is relatively high, and it has certain chemical activity. During the plastic encapsulation process, it can react chemically with some active groups in the plastic encapsulation material 30 to form chemical bonds, thereby improving the bonding force. For example, the copper surface is easily oxidized to form copper oxide, and copper oxide can react chemically with certain components in the plastic encapsulation material 30 to enhance the bonding between the two. On the other hand, the roughness of the copper surface is relatively high. After some surface treatment processes, a certain microstructure, such as tiny protrusions, gullies, etc., will be formed on its surface. This rough surface can increase the contact area with the plastic encapsulation material 30, so that the plastic encapsulation material 30 can better fill and adhere to the copper surface, thereby improving the mechanical interlocking effect and enhancing the bonding degree. Moreover, the thermal expansion coefficient of copper is close to that of the plastic encapsulation material 30. Electronic products will experience different temperature changes during use. Since the thermal expansion coefficients of copper and the plastic packaging material 30 are relatively matched, the thermal stress generated between the two during the thermal cycle is relatively small, which helps to maintain the bonding stability between the two and avoid problems such as cracking or peeling at the bonding interface due to excessive thermal stress.

[0041] In addition, since the lead body portion 42 is made of tin-plated copper and exposed outside the packaging material, its oxidation resistance and solderability can be improved and the heat dissipation performance can be improved.

[0042] Therefore, in summary, the packaging structure of the high thermal conductivity semiconductor device in this embodiment takes into account heat dissipation, processability, reliability and adaptability.

[0043] Furthermore, the heat sink 20 can be a heat sink or a heat sink of other structures, such as a composite structure with heat sink fins, etc. The shape of the heat sink can also be designed according to the needs, including but not limited to rectangular, diamond or irregular shapes, etc., to increase the heat dissipation area.

[0044] The heat sink 20 may be made of a material with high thermal conductivity such as copper or copper alloy.

[0045] In some embodiments, the filler of the molding compound 30 further includes crystalline silicon 32. That is, the filler of the molding compound 30 is a mixed filler including at least spherical silicon 31 and crystalline silicon 32.

[0046] The filler of the above-mentioned molding compound 30 also includes crystalline silicon 32, that is, the molding compound 30 has a mixed filler. Therefore, compared with a single molten filler, the thermal conductivity of the molding compound 30 body is improved. Therefore, the molding compound 30 can not only mechanically protect and electrically insulate the semiconductor chip 10 and the heat sink 20 and ensure the stability of the overall package to prevent the semiconductor chip 10 from being affected by the external environment, such as moisture, dust, mechanical impact, etc., but also, on the basis of the stable and fitting combination at the interface between the molding compound 30 and the heat sink 20 and the pin connection part 41, the improvement of the thermal conductivity of the molding compound 30 can be effectively utilized to help improve the heat dissipation efficiency.

[0047] Furthermore, the crystalline silicon 32 is less than the spherical silicon 31 to avoid defects similar to those of a single crystalline molding compound.

[0048] Furthermore, the crystalline silicon may be silicon dioxide or the like.

[0049] Lead Frame In some embodiments, the pin connection portion 41 is entirely made of bare copper.

[0050] In other embodiments, some of the pin connection parts 41 are bare copper, and some of the pin connection parts 41 are copper-plated with silver. Thus, the connection with the semiconductor chip is better taken into account by the copper-silver plating.

[0051] In some embodiments, the tin plating in the copper tin plating is pure tin or alloy tin.

[0052] In some embodiments, the lead frame is roughened to further increase the roughness of the lead frame surface, so that the pin connection portion 41 and the molding compound 30 have a stronger interface bonding ability, so as to further improve the anti-delamination ability.

[0053] It should be noted that the roughening treatment method is an existing technology in the field, including chemical roughening, electroplating roughening, laser roughening, etc., which is not limited here.

[0054] Of course, the wire frame may not be roughened.

[0055] In this embodiment, the ends 420 of the lead body 42 and the heat sink 20 are located on opposite sides of the semiconductor chip 10 .

[0056] In another embodiment, if Figure 2 As shown in FIG. 1 , the end 430 of the lead body 43 and the heat sink 20 are located on the same side of the semiconductor chip 10 .

[0057] That is to say, if Figure 1 and Figure 2 As shown in FIG. 1 , the connection surface 11 may be located on the upper surface of the semiconductor chip 10 (eg Figure 1), or may be located on the lower surface of the semiconductor chip 10 (as shown Figure 2 shown).

[0058] In this embodiment, the connection surface 11 and the heat sink 20 are filled with a thermally conductive adhesive 50. The thermally conductive adhesive 50 has good thermal conductivity, so that the heat of the semiconductor chip 10 can be transferred to the heat sink 20 more quickly, so that the heat dissipation channel formed by the semiconductor chip 10 and the heat sink 20 is more stable and efficient.

[0059] Specifically, the thermal conductive adhesive 50 may contain metal fillers such as silver.

[0060] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A packaging structure of a high thermal conductivity semiconductor device, characterized in that: include: A semiconductor chip, wherein a surface of the semiconductor chip includes a connection surface; A lead frame, comprising a heat sink and a plurality of pin structures, wherein the heat sink is arranged on the connection surface, the pin structure comprises a pin connection portion and a pin body portion, and at least part of the pin connection portion is bare copper, and the pin body portion is tin-plated copper; A molding compound, wherein the filler of the molding compound at least comprises spherical silicon, the molding compound wraps around the semiconductor chip and the heat sink and exposes at least a portion of the heat sink, so that the semiconductor chip and the heat sink are packaged together by the molding compound, and in addition, the pin connection portion is packaged in the molding compound, and the pin body portion is exposed outside the packaging compound.

2. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: The filler also includes crystalline silicon.

3. The packaging structure of a high thermal conductivity semiconductor device according to claim 2, characterized in that: The crystalline silicon is less than the spherical silicon.

4. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: The tin in the copper tin plating is pure tin or alloy tin.

5. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: The lead frame is roughened.

6. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: The pin connection parts are all bare copper.

7. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: Some of the pin connection parts are bare copper, and some of the pin connection parts are copper plated with silver.

8. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: The end of the lead body portion and the heat sink are located on the same side of the semiconductor chip.

9. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: The ends of the lead body and the heat sink are respectively located on two opposite sides of the semiconductor chip.

10. The packaging structure of a high thermal conductivity semiconductor device according to claim 1, characterized in that: The connection surface and the heat sink are filled with heat-conducting adhesive, and the heat sink and the connection surface are connected via the heat-conducting adhesive.

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