Packaging structure

Abstract

Some embodiments of this application provide a packaging structure, including: a substrate with a first metal layer disposed on its surface; a die attached to the first metal layer; a molding compound molding the die and the substrate; a thermally conductive layer disposed on the molding compound; and a plurality of thermally conductive vias extending from the thermally conductive layer through the molding compound and connecting to the first metal layer, wherein the plurality of thermally conductive vias have different groove and / or hole shapes. This application improves the overall heat dissipation capacity of the power module of the packaging structure by changing the structure of the molding compound and increasing the number of thermally conductive vias, thereby enhancing the overall reliability of the packaging structure.

Description

Technical Field

[0001] This application relates to the field of semiconductor structure technology, and more specifically, to a packaging structure. Background Technology

[0002] As electronic power systems gradually move towards higher power applications, such as electric vehicles, industrial drives, and renewable energy conversion, these applications require carrying larger currents and higher voltages. This causes power components (such as IGBTs (Insulated Gate Bipolar Transistors) and SiC MOSFETs (Silicon Carbide Metal Oxide Semiconductor Field Effect Transistors)) to generate a large amount of heat during switching. Therefore, effective heat dissipation is crucial for the reliability, performance, and lifespan of power modules. In other words, as electronic power systems move towards higher power, the voltage and current they need to withstand are also increasing, inevitably generating a large amount of heat. This can lead to excessively high internal thermal resistance of the package, mismatch in material thermal expansion, and thermal accumulation effects, resulting in limited heat dissipation performance. Because traditional packaging cannot effectively cope with the heat dissipation requirements of higher frequencies and higher currents, it is necessary to use materials with higher thermal conductivity (such as silver sintering and silver composite materials) and change the structure of the power module to improve its heat dissipation capacity and reliability. That is, it is necessary to optimize the overall heat dissipation performance by changing the structure.

[0003] See Figure 1A and Figure 1B , Figure 1A and Figure 1B The diagram illustrates a prior art packaging structure 10. In this structure 10, a substrate 11 has metal layers 11M formed on both sides, and a die 14 is attached to one side of the metal layer 11M, with a lead frame 13 disposed thereon. A portion of the substrate 11 and the lead frame 13 are molded from a molding compound 12. Figure 1B As shown, the heat sink 15 is placed on a molding compound 12, such as an epoxy composite material. It is evident that, for the existing encapsulation structure 10, the conventional approach is to directly perform the molding process and then place the heat sink 15 on the molding compound 12, such as an epoxy composite material, for heat dissipation. However, because the thermal conductivity of the molding compound 12, such as an epoxy composite material, is not good, the heat dissipation capacity of the encapsulation structure 10 is poor, which may cause thermal stress accumulation and affect performance. Utility Model Content

[0004] To address the aforementioned issues, this application incorporates heat dissipation channels within the molding compound. By allowing the highly thermally conductive material to directly contact the heat source, internal heat is rapidly dissipated to the heat sink via the thermally conductive layer. This improves the poor heat dissipation performance of existing packaging structures, enhances the overall heat dissipation capacity of the packaging structure (power module), and thereby improves the overall structural reliability. Thus, this application improves the heat dissipation capacity of the packaging structure (power module) through structural modifications.

[0005] Some embodiments of this application provide a packaging structure, including: a substrate having a first metal layer disposed on its surface; a die attached to the first metal layer; a molding compound molding the die and the substrate; a thermally conductive layer disposed on the molding compound; and a plurality of thermally conductive vias extending from the thermally conductive layer through the molding compound and connecting to the first metal layer, wherein the plurality of thermally conductive vias have different groove and / or hole shapes.

[0006] In some embodiments, in a cross-sectional view through the die and the heat-conducting through-hole, the heat-conducting through-hole has inclined sidewalls and a shape that is wider at the top and narrower at the bottom.

[0007] In some embodiments, in a cross-sectional view through the die and the thermally conductive via, the thermally conductive via has straight sidewalls.

[0008] In some embodiments, the heat-conducting through-hole with a groove shape is closer to the die than the heat-conducting through-hole with a hole shape.

[0009] In some embodiments, the heat-conducting through-hole with a groove shape is located near the first die, and the heat-conducting through-hole with a hole shape is located near the second die, wherein the coverage area of ​​the first die is larger than the coverage area of ​​the second die.

[0010] In some embodiments, the thermally conductive layer extends continuously over the molding compound and across the entire top surface of the molding compound.

[0011] In some embodiments, the top of the molding compound has a groove, and the thermally conductive layer is disposed in the groove.

[0012] In some embodiments, the thermally conductive layer covers a portion of the molding compound.

[0013] In some embodiments, the top surface of the molding compound is flush with, or lower than or higher than, the top surface of the thermally conductive layer.

[0014] In some embodiments, the packaging structure further includes: a second metal layer disposed on the side of the substrate opposite to the first metal layer; and a heat sink disposed on the thermally conductive layer and on the second metal layer of the substrate.

[0015] In some embodiments, the heat sink covers a portion of the thermally conductive layer and a portion of the second metal layer, respectively.

[0016] In some embodiments, the portion of the heat sink away from the heat-conducting layer has a serrated structure.

[0017] In some embodiments, the portion of the heat sink away from the second metal layer has a serrated structure.

[0018] In some embodiments, in a top view, the groove has a square shape and the hole has a circular shape.

[0019] In some embodiments, an interface exists between the thermally conductive layer and the thermally conductive via.

[0020] In some embodiments, the packaging structure further includes a lead frame connected to the first metal layer and extending to the outside of the molding compound, wherein the die is connected to the lead frame via leads.

[0021] In some embodiments, the substrate further has a second metal layer opposite to the first metal layer and a ceramic core sandwiched between the first metal layer and the second metal layer.

[0022] Other embodiments of this application provide a packaging structure including: a substrate having a first metal layer disposed on its surface; a die attached to the first metal layer; a molding compound molding the die and the substrate; and a plurality of thermally conductive vias disposed around the die and extending through the molding compound to connect to the first metal layer, wherein the thermally conductive vias have different shapes.

[0023] In some embodiments, the plurality of heat-conducting through-holes have different groove and / or hole shapes, wherein, in a cross-sectional view through the die and the heat-conducting through-holes, a portion of the heat-conducting through-holes has a groove shape, and the groove shape has inclined sidewalls and a shape that is wider at the top and narrower at the bottom, and another portion of the heat-conducting through-holes has a hole shape, and the hole shape has straight sidewalls.

[0024] In some embodiments, the encapsulation structure further includes a thermally conductive layer disposed on the molding compound and connected to the thermally conductive via.

[0025] This application improves the overall heat dissipation capacity of the power module by changing the structure of the molding compound and adding thermally conductive vias, thereby enhancing the overall reliability of the packaging structure. Attached Figure Description

[0026] The various aspects of this utility model can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industrial practice, the various components are not drawn to scale. In fact, for clarity of discussion, the dimensions of the various components may be arbitrarily increased or decreased.

[0027] Figures 1A to 1BThe packaging structure of the prior art is shown.

[0028] Figure 2 , Figures 2A to 2B , Figures 3 to 6 The packaging structure according to some embodiments of this application is shown.

[0029] Figures 7 to 15 The process for forming a packaging structure according to some embodiments of this application is illustrated. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art are within the scope of protection of this application. In addition, when using terms such as "approximately," "about," "substantial," or "basically" to describe numerical values ​​or numerical ranges, unless otherwise stated, the term is intended to cover values ​​within ±10% of the described value. For example, the term "about 5nm" covers a size range from 4.5nm to 5.5nm.

[0031] To address the aforementioned issues, this application improves the heat dissipation capability of the packaging structure (power module) by altering the structure of the molding compound. By changing the structure of the molding compound and increasing heat dissipation channels, the heat is directly contacted by a high thermal conductivity material, allowing internal heat to be quickly conducted to the heat sink through thermally conductive holes and a thermally conductive layer. This improves the poor heat dissipation performance of existing packaging structures, enhances the overall heat dissipation capability of the power module, and thus improves the overall reliability of the structure.

[0032] Specifically, see Figure 2 , Figure 2 A packaging structure 100 according to some embodiments of this application is shown. From Figure 2 As can be seen, the packaging structure 100 includes: a substrate 101, on one side of which a first metal layer 101M1 is disposed; a die 104 attached to the first metal layer 101M1; a molding compound 102 molding the die 104 and the substrate 101; a thermally conductive layer 105 disposed on the molding compound 102; and a plurality of thermally conductive vias 106 extending from the thermally conductive layer 105 through the molding compound 102 and connecting to the first metal layer 101M1. Further, Figure 2A and Figure 2B A top view of the substrate 101, die 104, and corresponding plurality of thermally conductive vias 106 is shown, combined with Figure 2 as well as Figures 2A to 2B It can be seen that the multiple heat-conducting through-holes 106 have different groove and / or hole shapes, specifically, such as Figure 2A and Figure 2B As shown, the heat-conducting through-holes 1061 among the plurality of heat-conducting through-holes 106 have a groove shape, and the heat-conducting through-holes 1062 among the plurality of heat-conducting through-holes 106 have a hole shape, and multiple heat-conducting through-holes 106 of different shapes can be provided between adjacent tubes 104. It should be understood that Figure 2A and Figure 2B The relative positions of the die 104 and the multiple heat-conducting through holes 106 are only schematically shown, and there is no particular limitation on the number of the multiple heat-conducting through holes 106.

[0033] In some embodiments, the grooved thermal via 1061 is closer to the die 104 than the hole-shaped thermal via 1062 because the grooved thermal via 1061 can provide better heat dissipation. Specifically, see Figure 2A and Figure 2B A groove-shaped heat-conducting through-hole 1061 is located near the first die 1041, and a hole-shaped heat-conducting through-hole 1062 is located near the second die 1042. The coverage area of ​​the first die 1041 is larger than that of the second die 1042; that is, the groove-shaped heat-conducting through-hole 1061 is located near the larger die 104. In other words, for the heat-conducting through-hole 106, a groove shape can be used at the die 104 with higher heat generation to increase the heat dissipation area, while a hole shape can be used at the die 104 with lower heat generation. Therefore, this application provides heat-conducting through-holes 106 (heat dissipation channels) between the dies 104 at locations with higher heat generation, and the shape of the heat-conducting through-hole 106 can be determined according to the heat generation, providing concentrated heat dissipation efficiency.

[0034] Further as Figure 2A and Figure 2B As shown in the top view, the groove has a square shape and the hole has a circular shape, but this is not the only possibility. In some embodiments, the groove may also have a circular shape and the hole may have a square shape. This can be set according to the actual situation, and both the groove and the hole can have any suitable shape. Figure 2A and Figure 2B In the embodiment shown, there may be no interface between the thermally conductive layer 105 and the thermally conductive via 106. In this embodiment, the thermally conductive layer 105 and the thermally conductive via 106 may be integrally formed using the same material. However, in other embodiments, there may be an interface between the thermally conductive layer 105 and the thermally conductive via 106, which will be described in detail below.

[0035] See back Figure 2 ,exist Figure 2In the cross-sectional view showing the through-hole 104 and the thermally conductive via 106, the thermally conductive via 106 has sloping sidewalls and a shape that is wider at the top and narrower at the bottom; that is, the thermally conductive via has tapered sidewalls in the direction D toward the substrate 101. In some embodiments, in the cross-sectional view showing the through-hole 104 and the thermally conductive via 106, the thermally conductive via 106 has straight sidewalls; that is, the thermally conductive via 106 may be of equal width at the top and bottom, which will be described in detail below. In some embodiments, the thermally conductive layer 105 extends continuously over the molding compound 102 and spans the entire top surface of the molding compound 102. In other embodiments, such as Figure 3 The encapsulation structure 200 shown has a groove R on the top of the molding compound 102, and the thermally conductive layer 105 is disposed in the groove R. In this embodiment, the groove for accommodating the thermally conductive layer 105 can be cut into the top surface of the molding compound 102. Further, in some embodiments, the top surface of the molding compound 102 may be flush with the top surface of the thermally conductive layer 105, or the top surface of the molding compound 102 may be lower or higher than the top surface of the thermally conductive layer 105. In some other embodiments, the thermally conductive layer 105 only covers a portion of the molding compound 102 (i.e., it does not necessarily completely cover the upper surface of the molding compound 102), such as in... Figure 2 The package structure 100 shown or Figure 3 The packaging structure 200 shown is as follows.

[0036] In addition, from Figure 2 It can also be seen that the package structure 100 further includes: a lead frame 103, connected to the first metal layer 101M1 and extending to the outside of the molding compound 102, wherein the die 104 is connected to the lead frame 103 via a lead 107. Further as... Figure 2 As shown, the substrate 101 further has a second metal layer 101M2 opposite to the first metal layer 101M1 and a ceramic core 101C sandwiched between the first metal layer 101M1 and the second metal layer 101M2. In some embodiments, the substrate 101 is a copper-clad ceramic substrate. In some embodiments, a molding compound 102 surrounds the substrate 101 from three sides and includes the second metal layer 101M2 of the substrate 101.

[0037] Next, see Figure 4 , Figure 4 The corresponding package structure 300 is shown. In such a case... Figure 3 In the illustrated embodiment, the packaging structure 300 further includes a heat sink 108, which is disposed on the thermally conductive layer 105 and on the second metal layer 101M2 of the substrate 101. As shown above, the second metal layer 101M2 is disposed on the side of the substrate 101 opposite to the first metal layer 101M1. Figure 4As can be seen, the heat sink 108 covers a portion of the thermally conductive layer 105 and a portion of the second metal layer 101M2. Furthermore, the portions of the heat sink 108 away from the thermally conductive layer 105 and away from the second metal layer 101M2 have a serrated structure to facilitate heat dissipation.

[0038] See Figure 5 , Figure 5 The package structure 400 is shown, from Figure 5 As can be seen in the packaging structure 400, in the cross-sectional view passing through the die 104 and the thermal via 106, the thermal via 106 can have straight sidewalls or inclined sidewalls. See [link to documentation]. Figure 6 , Figure 6 The package structure 500 is shown, from Figure 6 As can be seen from the encapsulation structure 500, an interface can exist between the thermally conductive via 106 and the thermally conductive layer 105. In this case, the thermally conductive via 106 and the thermally conductive layer 105 can be formed using different thermally conductive materials. That is to say, the thermally conductive material of the thermally conductive via 106 and the thermally conductive layer 105 are not necessarily the same, but can be different.

[0039] Return to reference Figure 2 , Figure 2A and Figure 2B Other embodiments of this application also provide a packaging structure 100, including: a substrate 101, on which a first metal layer 101M1 is disposed; a die 104 attached to the first metal layer 101M1; a molding compound 102 molding the die 104 and the substrate 101; and a plurality of thermally conductive vias 106 disposed around the die 104 and extending through the molding compound 102 to connect to the first metal layer 101M1, wherein the thermally conductive vias 106 have different shapes. In some embodiments, the plurality of thermally conductive vias 106 have different groove and / or hole shapes, wherein, in a cross-sectional view of the die 104 and the thermally conductive vias 106, a portion of the thermally conductive vias 106 has a groove shape, and the groove shape has inclined sidewalls and a shape that is wider at the top and narrower at the bottom; another portion of the thermally conductive vias 106 has a hole shape, and the hole shape has straight sidewalls. In some embodiments, the encapsulation structure 100 further includes a thermally conductive layer 105 disposed on the molding compound 102 and connected to the thermally conductive via 106.

[0040] In the above embodiments, the first metal layer 101M1 and the second metal layer 101M2 may include copper metal layers, etc., and the lead frame 103 may be made of metals such as copper, gold, silver, etc. In some embodiments, the thermally conductive via 106 and the thermally conductive layer 105 may be made of thermally conductive materials, such as copper paste, solder paste, and thermally conductive materials of metals such as copper. In some embodiments, the heat sink 108 may include materials such as metals. In some embodiments, the molding compound 102 may include molding compound, epoxy composite material, etc.

[0041] The packaging structure 100-500 provided in this application is superior to the existing packaging structure 10, as detailed below:

[0042] In the existing packaging structure 10, after the molding process, the heat sink 15 is placed on the molding compound 12, such as epoxy composite material, for heat dissipation. However, because the thermal conductivity of the molding compound 12, such as epoxy composite material, is not excellent, the heat dissipation capacity of the packaging structure 10 is poor, which may cause thermal stress accumulation and affect performance. In the packaging structure 100-500 provided in this application, by changing the structure of the molding compound 102 and adding thermally conductive through holes 106 (heat dissipation channels), the internal heat is quickly conducted to the heat sink 108 through the thermally conductive layer 105, thereby improving the overall performance of the packaging structure 100-500.

[0043] The following reference Figures 7 to 10 Let me introduce Figure 4 The forming process of the package structure 300 shown.

[0044] See Figure 7 A substrate 101 molded from a molding compound 102, such as an epoxy composite material, is provided. The substrate 101 is a copper-clad ceramic substrate having a ceramic core 101C and a first metal layer 101M1 and a second metal layer 101M2 disposed on opposite sides of the ceramic core 101C. Further, a die 104 and a lead frame 103 are formed on the first metal layer 101M1, and a heat sink 108 is formed on the portion of the second metal layer 101M2 exposed by the molding compound 102. Figure 7 As shown, the structure of the molding compound 102 is modified using laser drilling and mold drilling processes P1, such as... Figure 8 As shown, an opening 106O is formed in the molding compound 102 to expose the first metal layer 101M1.

[0045] Next, see Figure 8 A high thermal conductivity paste is applied to the molding compound 102 and fills the interior of the openings 106O using a printing process, thereby forming a plurality of thermally conductive through-holes 106 and a thermally conductive layer 105. In some embodiments, the thermally conductive paste may include a metal paste such as copper paste. See then... Figure 9 The heat sink 108 is placed on the thermally conductive layer 105, and metal bonding is performed using sintering processes commonly used in the art (such as about 150°C to about 200°C) to form a Figure 4 The packaging structure 300 is shown.

[0046] In the above process, the structure of the molding compound 102 is first modified and thermally conductive vias 106 and thermally conductive layer 105 are added for heat dissipation. Since the purpose of this scheme is to conduct heat quickly, the thermally conductive layer needs to use a material with high thermal conductivity. A high thermal conductivity paste can be used. The paste is printed onto the area of ​​the thermally conductive layer 105 and the vias 106. Then, the heat sink 108 is placed on the paste of the thermally conductive layer 105 and metal bonded, thereby realizing the rapid heat conduction of the encapsulation structure 300.

[0047] The following reference Figures 11 to 15 Let me introduce Figure 6 The forming process of the package structure 500 shown.

[0048] Reference Figure 11 The above-mentioned Figure 7 Similar processes modify the structure of molding compound 102, such as Figure 11 As shown, the molding compound 102 is opened to form openings 106O. See also Figure 12 The opening 106O is filled using a sputtering process P2. In some embodiments, a metal such as copper can be used. After filling the opening 106O, a structure is formed as follows: Figure 13 The multiple heat-conducting through holes 106 shown are illustrated.

[0049] See afterward. Figure 14 A high thermal conductivity film, such as copper paste or silver paste, is placed over the molding compound 102 and multiple thermally conductive vias 106 to form a thermally conductive layer 105. Finally, see Figure 15 The heat sink 108 is placed on the thermally conductive layer 105, allowing it to bond with the thermal interface material of the thermally conductive layer 105. Finally, metal bonding is performed using a sintering process commonly used in the art, thereby forming... Figure 6 The packaging structure shown is 500.

[0050] In the above process, the structure of the molding compound 102 is first modified and thermally conductive vias 106 and thermally conductive layers 105 are added for heat dissipation. The opening 106 is filled with a high thermal conductivity material until it reaches the same height as the molding compound 102, such as an epoxy composite material, to form the thermally conductive via 106. Then, a thermal interface material is covered on top to form the thermally conductive layer 105. Finally, the heat sink 108 is placed on top, thereby achieving rapid heat conduction of the encapsulation structure 500.

[0051] As can be seen above, in order to achieve rapid heat conduction of the packaging structure 100-500, this application can create an opening 106O in the form of a pre-drilled hole during or after the molding process. Then, a high thermal conductivity material is filled into the channel to form a thermally conductive through hole 106 (heat dissipation channel), which is in direct contact with the heat source to achieve efficient heat dissipation.

[0052] In summary, this application improves the heat dissipation capability of the packaging structure 100-500 by modifying the structure. By changing the molding compound structure and adding heat dissipation channels (thermal conductive vias 106), the high thermal conductivity material of the thermal conductive vias 106 directly contacts the heat source, and the internal heat is quickly conducted to the heat sink through the thermal conductive vias 106 and the thermal conductive layer 105, thereby improving the overall heat dissipation capability of the power module of the packaging structure 100-500 and improving the overall reliability of the structure.

[0053] The features of several embodiments have been summarized above to enable those skilled in the art to better understand aspects of the present invention. Those skilled in the art should understand that they can readily use the present invention as a basis to design or modify other processes and structures for implementing the same purposes and / or achieving the same advantages as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of the present invention, and that various changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the present invention.

Claims

1. A packaging structure, comprising: A substrate, wherein a first metal layer is disposed on the surface of the substrate; The die is attached to the first metal layer; A molding compound is used to mold the die and the substrate; A thermally conductive layer is disposed on the molding compound; as well as Multiple thermally conductive vias extend from the thermally conductive layer, through the molding compound, and connect to the first metal layer. The plurality of heat-conducting through holes have different groove and / or hole shapes.

2. The package structure of claim 1, wherein, In the cross-sectional view through the tube and the heat-conducting through-hole, the heat-conducting through-hole has inclined sidewalls and a shape that is wider at the top and narrower at the bottom.

3. The package structure of claim 1, wherein, In the cross-sectional view through the tube and the heat-conducting through-hole, the heat-conducting through-hole has straight sidewalls.

4. The package structure of claim 1, wherein, The heat-conducting through-hole with a groove shape is located near the first die of the tube, and the heat-conducting through-hole with a hole shape is located near the second die of the tube, wherein the coverage area of ​​the first die is larger than the coverage area of ​​the second die.

5. The package structure of claim 1, wherein, The thermally conductive layer extends continuously over the molding compound and spans the entire top surface of the molding compound.

6. The package structure of claim 1, wherein, The top of the molded compound has a groove, and the thermally conductive layer is disposed in the groove.

7. The packaging structure according to claim 1, further comprising: A second metal layer is disposed on the side of the substrate opposite to the first metal layer; as well as A heat sink is disposed on the thermally conductive layer and on the second metal layer of the substrate.

8. The package structure of claim 1, wherein, In the top view, the groove has a square shape, and the hole has a circular shape.

9. The package structure of claim 1, wherein, An interface exists between the thermally conductive layer and the thermally conductive through-hole.

10. The packaging structure according to claim 1, further comprising: A lead frame is connected to the first metal layer and extends to the outside of the molding compound, wherein the die is connected to the lead frame via leads.

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