Packaging structure

Abstract

The present application provides a packaging structure, comprising: a lead frame; a power device, comprising a substrate, an active layer, a plurality of first electrodes, a plurality of second electrodes, and a third electrode, the plurality of first electrodes have different potentials from the plurality of second electrodes, and the plurality of first electrodes and the plurality of second electrodes are arranged in an interleaved manner; a plurality of first bumps disposed on each of the first electrodes; a plurality of second bumps disposed on each of the second electrodes, the plurality of first bumps and the plurality of second bumps connected to the lead frame; a conductive unit, a first side of the conductive unit connected to the substrate of the power device, the conductive unit connected to the lead frame; and a packaging material covering the power device and the lead frame, a second side of the conductive unit exposed from the packaging material.

Description

Technical Field

[0001] The present invention relates to a packaging structure, and more particularly to a packaging structure having a plurality of protrusions having different polarities and arranged in an alternating manner between a lead frame and a power device. Background Technology

[0002] Flip chip packaging describes a method of electrically connecting a die to a package carrier. For example, a substrate or leadframe serving as the package carrier provides the connection from the die to the outside of the package. In standard packaging processes, wires are used to form the internal connection between the die and the carrier. The die is attached to the carrier face up, and then the wires are first bonded to the die, then wrapped around and bonded to the carrier. Generally, the wire length is between 1-5 cm and the diameter is between 15-35 micrometers.

[0003] In contrast, in flip-chip packaging, the internal connection between the die and the carrier is formed by conductive bumps placed directly on the die surface. The die with the bumps is flipped face down, so that the bumps are directly connected to the carrier. Generally, the height of the bumps is between 60-100 micrometers, and the diameter is between 80-125 micrometers. Flip-chip connections are generally formed in two ways: using solder or using conductive adhesive.

[0004] The use of flip-chip interconnection offers users many potential advantages: reduced signal inductance due to the significantly shortened interconnect length (0.1 cm vs. 1-5 cm), resulting in a substantial reduction in signal path inductance, a key factor for high-speed communication and switching devices; reduced power / ground inductance, allowing power to be directly introduced to the die core without being routed to the edges, significantly reducing core power noise and improving silicon performance; high signal density, enabling the use of the entire die surface as interconnects, not just the edges, similar to the comparison between QFP and BGA packages, where flip-chip interconnects can connect to the die surface, supporting a large number of interconnects within the same die size; and die miniaturization, reducing die size and saving silicon costs compared to pad-limited dies (die size is determined by the edge space required by the bonding pads). However, because the die is directly connected to the carrier only through conductive bumps, the distance between the die and the carrier is insufficient, leading to a drop in breakdown voltage.

[0005] Furthermore, compared to the traditional method of bonding the die with wire bonding, high-power packages and discrete devices such as MOSFETs, IGBTs, and switched output differential structures (SODs) use copper clips to connect the die to the base substrate and / or leadframe. Clip bonding technology replaces the standard wire bonding connection between the die and the leadframe with a solid copper bridge.

[0006] However, the solid copper bridges (e.g., copper metal clips) used in clip bonding packages are also encapsulated by the packaging material, resulting in poor heat dissipation of the encapsulated copper metal clips.

[0007] Therefore, it is highly anticipated to develop a packaging structure that utilizes flip-chip and metal bonding technology to improve breakdown voltage and achieve good heat dissipation. Summary of the Invention

[0008] According to an embodiment of the present invention, a packaging structure is provided, comprising: a lead frame; a power device including a substrate, an active layer, a plurality of first electrodes, a plurality of second electrodes, and a third electrode, wherein the active layer is disposed on the substrate, the plurality of first electrodes, the plurality of second electrodes, and the third electrode are disposed on the active layer, wherein the potentials of the plurality of first electrodes are different from the potentials of the plurality of second electrodes, and the plurality of first electrodes and the plurality of second electrodes are arranged in an alternating manner; a plurality of first protrusions disposed on each of the first electrodes; a plurality of second protrusions disposed on each of the second electrodes, wherein the plurality of first protrusions and the plurality of second protrusions are connected to the lead frame; a conductive unit having a first portion, a second portion, and an upper surface, wherein the first portion of the conductive unit is connected to the substrate of the power device, and the second portion of the conductive unit is connected to the lead frame; and a packaging material covering the power device and the lead frame, wherein a portion of the upper surface of the conductive unit is exposed by the packaging material.

[0009] In some embodiments, the power device is a one-sided power element. In some embodiments, the plurality of first electrodes include sources, the plurality of second electrodes include drains, and the third electrode includes a gate.

[0010] In some embodiments, the plurality of first protrusions and the plurality of second protrusions are made of copper, tin, gold, or combinations thereof. In some embodiments, the plurality of first protrusions and the plurality of second protrusions comprise cylinders. In some embodiments, the plurality of first protrusions and the plurality of second protrusions have a diameter of at least 65 micrometers. In some embodiments, the plurality of first protrusions have a first spacing of at least 40 micrometers. In some embodiments, the spacing of the plurality of second protrusions is the same as the first spacing of the plurality of first protrusions. In some embodiments, the first spacing is less than or equal to the diameter of the plurality of first protrusions and the plurality of second protrusions. In some embodiments, the plurality of first protrusions and the plurality of second protrusions have a second spacing of at least 65 micrometers. In some embodiments, the second spacing is greater than or equal to 1.6 times the first spacing.

[0011] In some embodiments, the conductive unit includes copper. In some embodiments, the conductive unit includes a metal clip. In some embodiments, the substrate of the power device has a first surface area, and the portion of the upper surface of the conductive unit exposed from the encapsulation material has a second surface area, the second surface area being greater than or equal to 1.2 times the first surface area.

[0012] In some embodiments, the packaging structure of the present invention further includes a plurality of metal pads disposed between the lead frame and the plurality of first protrusions and the plurality of second protrusions. In some embodiments, the plurality of metal pads are made of copper, silver, gold, tin, or combinations thereof. In some embodiments, the plurality of metal pads have a width less than or equal to the diameter of the plurality of first protrusions and the plurality of second protrusions.

[0013] In some embodiments, the lead frame and the power device have a third spacing, which is at least 60 micrometers.

[0014] In some embodiments, the packaging structure of the present invention further includes a patterned passivation layer covering the active layer and a portion of the plurality of first electrodes and the plurality of second electrodes. In some embodiments, the packaging structure of the present invention further includes a patterned polymer layer covering the patterned passivation layer and a portion of the plurality of first electrodes and the plurality of second electrodes, forming a plurality of openings. In some embodiments, the packaging structure of the present invention further includes a plurality of metal layers disposed on the sidewalls and bottom of the plurality of openings, and electrically connecting the plurality of first electrodes and the plurality of second electrodes. In some embodiments, the plurality of first protrusions and the plurality of second protrusions are connected to the plurality of first electrodes and the plurality of second electrodes through the plurality of metal layers.

[0015] In one embodiment of the invention, flip-chip technology is used to mount a power element on a conductor frame via multiple protrusions (e.g., copper pillars) to connect the source and drain. The source (first protrusion) with a low potential and the drain (second protrusion) with a high potential are arranged alternately. The spacing between protrusions of different polarities on different electrodes is greater than or equal to 1.6 times the spacing between protrusions of the same polarity on the same electrode. The configuration and size of the element of the present invention have the following advantages: narrow spacing between adjacent protrusions; reduced parasitic inductance due to the replacement of conventional wire bonding connections; increased breakdown voltage due to the increased distance between the power element and the lead frame (at least 60 micrometers or more) by protrusions of appropriate height; and high reliability of the packaged product.

[0016] In lateral power devices, the source and drain are located on the same side of the semiconductor substrate. Current flows from the high-potential drain to the low-potential source via active lamination without passing through the semiconductor substrate, thus avoiding parasitic resistance and inductance generated on the semiconductor substrate during device operation. Furthermore, conductive elements (e.g., metal connectors) extend from the semiconductor substrate to the lead frame, replacing the traditional wire bonding method that requires two wires to extend from both ends of the semiconductor substrate to the lead frame, effectively reducing the overall package size.

[0017] Furthermore, a package structure with exposed conductive units (i.e., a package structure with at least a portion of conductive units not covered by the package material, for example, the surface area of ​​the exposed conductive units is approximately greater than or equal to 1.2 times the back surface area of ​​the power device substrate) can achieve good bidirectional heat dissipation and improve component performance. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of an encapsulation structure according to an embodiment of the present invention;

[0019] Figure 2 This is a partial top view of an encapsulation structure according to an embodiment of the present invention;

[0020] Figure 3 This is a partial cross-sectional view of an encapsulation structure according to an embodiment of the present invention;

[0021] Figure 4 This is a partial cross-sectional view of a packaging structure according to an embodiment of the present invention; and

[0022] Figure 5 This is an exploded view of a packaging structure according to an embodiment of the present invention.

[0023] [Symbol Explanation]

[0024] 10: Packaging Structure

[0025] 12: Conductor frame

[0026] 14: Power Device

[0027] 16: First protrusion

[0028] 18: Second protrusion

[0029] 20: Third protrusion

[0030] 22: Conductive unit

[0031] 22a: Lower surface of the conductive unit

[0032] 22b: Upper surface of the conductive unit

[0033] 23: Foot Attachment

[0034] 24: Packaging materials

[0035] 26:Substrate

[0036] 28: Active Layer

[0037] 30: First electrode

[0038] 32: Second electrode

[0039] 34: Third electrode

[0040] 36: Metal Pad

[0041] 36': Adhesive layer

[0042] 38: Patterned passivation layer

[0043] 40: Patterned polymer layer

[0044] 42: Opening

[0045] 44: Metal layer

[0046] A1: First surface area

[0047] A2: Second surface area

[0048] D: Diameter of the first, second, and third protrusions

[0049] H: Spacing between conductor frame and power unit

[0050] S1: First spacing

[0051] S2: Distance between the first protrusion and the second protrusion

[0052] W: Width of the metal pad Detailed Implementation

[0053] Please see Figure 1-5 According to an embodiment of the present invention, a packaging structure 10 is provided. Figure 1 This is a cross-sectional view of the packaging structure 10. Figure 2 This is a partial top view of the encapsulation structure 10. Figure 3 For along Figure 2 Partial cross-sectional view of the packaging structure 10 obtained by the A-A' section line. Figure 4 for Figure 1 A magnified view of a portion of the image. Figure 5 This is an exploded view of the encapsulation structure 10.

[0054] like Figure 1 As shown, the package structure 10 includes a lead frame 12, a power device 14, a plurality of first protrusions 16, a plurality of second protrusions 18, a plurality of third protrusions 20, a conductive unit 22, and a package material 24. The detailed structure of the power device 14 is disclosed in [details omitted]. Figure 2 , 3The power device 14 includes a substrate 26, an active layer 28, a plurality of first electrodes 30, a plurality of second electrodes 32, and a third electrode 34. The active layer 28 is disposed on the substrate 26. The first electrodes 30, second electrodes 32, and third electrodes 34 are disposed on the active layer 28. In this embodiment, the first electrodes 30, second electrodes 32, and third electrodes 34 include strip-shaped electrodes. In other embodiments, the first electrodes 30, second electrodes 32, and third electrodes 34 include other suitable shapes for the subsequent configuration of a plurality of protrusions. A "strip-shaped electrode" refers to an electrode extending from one side of the substrate 26 to a position adjacent to the opposite side of the substrate 26. The potential of the first electrode 30 is different from the potential of the second electrode 32; for example, the first electrode 30 is at a low potential, and the second electrode 32 is at a high potential. It is worth noting that the first electrode 30 with a low potential and the second electrode 32 with a high potential are arranged alternately on the active layer 28. That is, a first electrode 30 with a low potential, a second electrode 32 with a high potential, another first electrode 30 with a low potential, and another second electrode 32 with a high potential are arranged alternately on the active layer 28. A first protrusion 16 is disposed on each first electrode 30 to form a row of first protrusions 16 disposed on each strip-shaped first electrode 30. A second protrusion 18 is disposed on each second electrode 32 to form a row of second protrusions 18 disposed on each strip-shaped second electrode 32. A third protrusion 20 is disposed on a third electrode 34 to form a row of third protrusions 20 disposed on the strip-shaped third electrode 34. Similarly, since the first protrusion 16 and the second protrusion 18 are connected to electrodes with different potentials, the potential (polarity) of the first protrusion 16 is different from that of the second protrusion 18. For example, the first protrusion 16 is at a low potential and the second protrusion 18 is at a high potential. It is worth noting that the first protrusion 16 with a low potential and the second protrusion 18 with a high potential are arranged in an alternating manner. That is, a row of first protrusions 16 with a low potential, a row of second protrusions 18 with a high potential, another row of first protrusions 16 with a low potential, and another row of second protrusions 18 with a high potential are respectively arranged in an alternating manner on the first electrode 30 and the second electrode 32.

[0055] In some embodiments, the power device 14 may include a lateral power component, such as a gallium nitride active element. In some embodiments, the first electrode 30 may include a source, the second electrode 32 may include a drain, and the third electrode 34 may include a gate.

[0056] In some embodiments, the first protrusion 16, the second protrusion 18, and the third protrusion 20 may be made of copper, tin, gold, or a combination thereof. In this embodiment, the first protrusion 16, the second protrusion 18, and the third protrusion 20 are cylindrical. In some embodiments, the first protrusion 16, the second protrusion 18, and the third protrusion 20 may include other suitable shapes. Detailed dimensions of the components are disclosed in [the relevant document / details]. Figure 2-4 When the first protrusion 16, the second protrusion 18, and the third protrusion 20 are cylindrical, the diameter D of the first protrusion 16, the second protrusion 18, and the third protrusion 20 is at least 65 micrometers. The first spacing S1 of the first protrusion 16 is at least 40 micrometers. The spacing of the second protrusion 18 is the same as the first spacing S1 of the first protrusion 16. Similarly, the spacing of the third protrusion 20 is the same as the first spacing S1 of the first protrusion 16. "First spacing S1" refers to the spacing between protrusions of the same polarity disposed on the same electrode. The first spacing S1 is approximately less than or equal to the diameter D of the first protrusion 16, the second protrusion 18, and the third protrusion 20. Furthermore, the second spacing S2 between one of the first protrusions 16 and one of the second protrusions 18 is at least 65 micrometers. "Second spacing S2" refers to the spacing between protrusions of different polarities disposed on different electrodes. The second spacing S2 is approximately greater than or equal to 1.6 times the first spacing S1. The third spacing H between the lead frame 12 and the power device 14 is at least 60 micrometers.

[0057] exist Figure 1 In this configuration, the power device 14 is connected to the lead frame 12 via a first protrusion 16, a second protrusion 18, and a third protrusion 20. The conductive unit 22 includes a first portion contacting the substrate 26 of the power device 14, a second portion contacting the lead frame 12, an upper surface 22b, and a lower surface 22a. The first portion of the conductive unit 22 is connected to the substrate 26 of the power device 14 via a portion of its lower surface 22a. The second portion of the conductive unit 22 is connected to the lead frame 12 via a portion of its lower surface 22a, forming a pin 23. In some embodiments, the conductive unit 22 may include multiple pins connected to the lead frame 12. An encapsulation material 24 covers the power device 14 and the lead frame 12. A portion of the upper surface 22b of the conductive unit 22 is exposed above the encapsulation material 24.

[0058] In some embodiments, the conductive unit 22 may include copper. In some embodiments, the conductive unit 22 may include a metal clip. Figure 1 In the diagram, the substrate 26 of the power device 14 has a first surface area A1. The portion of the upper surface 22b of the conductive unit 22 exposed from the encapsulation material 24 has a second surface area A2. The second surface area A2 is approximately greater than or equal to 1.2 times the first surface area A1. According to the exploded view of the encapsulation structure 10 (e.g., Figure 5As shown in the figure, the dimensional relationship between the conductive unit 22 and the power device 14 is revealed more clearly.

[0059] Other related components are disclosed in Figure 3 The encapsulation structure 10 also includes an adhesive layer 36' disposed on the first protrusion 16, the second protrusion 18, and the third protrusion 20. In some embodiments, the adhesive layer 36' may include solder. The first protrusion 16, the second protrusion 18, and the third protrusion 20 are also connected to 1812 via a plurality of metal pads 36, such as Figure 1 , 4 As shown. In some embodiments, the metal pad 36 may be made of copper, silver, gold, tin, or a combination thereof. The width W of the metal pad 36 is approximately less than or equal to the diameter D of the first protrusion 16, the second protrusion 18, and the third protrusion 20, as shown. Figure 4 As shown.

[0060] exist Figure 3 In the encapsulation structure 10, a patterned passivation layer 38 is further included, covering the active layer 28 and a portion of the first electrode 30, the second electrode 32, and the third electrode 34. The encapsulation structure 10 also includes a patterned polymer layer 40, covering the patterned passivation layer 38 and a portion of the first electrode 30, the second electrode 32, and the third electrode 34 to form multiple openings 42. The encapsulation structure 10 also includes multiple metal layers 44 disposed on the sidewalls and bottom of the openings 42, and electrically connecting the first electrode 30, the second electrode 32, and the third electrode 34. In some embodiments, the metal layers 44 serve as under bump metal (UBM) layers to facilitate subsequent electroplating processes of the first protrusion 16, the second protrusion 18, and the third protrusion 20. The first protrusion 16, the second protrusion 18, and the third protrusion 20 are connected to the first electrode 30, the second electrode 32, and the third electrode 34 through the metal layers 44.

[0061] In one embodiment of the invention, flip-chip technology is used to mount a power element on a conductor frame via multiple protrusions (e.g., copper pillars) to connect the source and drain. The source (first protrusion) with a low potential and the drain (second protrusion) with a high potential are arranged alternately. The spacing between protrusions of different polarities on different electrodes is approximately greater than or equal to 1.6 times the spacing between protrusions of the same polarity on the same electrode. The configuration and size of the element of the present invention offer the following advantages: narrow spacing between adjacent protrusions; reduced parasitic inductance due to the replacement of conventional wire bonding connections; increased breakdown voltage due to the increased distance between the power element and the conductor frame (at least 60 micrometers or more) via protrusions of appropriate height; and high reliability of the packaged product.

[0062] In lateral power devices, the source and drain are located on the same side of the semiconductor substrate. Current flows from the high-potential drain to the low-potential source via active lamination without passing through the semiconductor substrate, thus avoiding parasitic resistance and inductance generated on the semiconductor substrate during device operation. Furthermore, conductive elements (e.g., metal connectors) extend from the semiconductor substrate to the lead frame, replacing the traditional wire bonding method that requires two wires to extend from both ends of the semiconductor substrate to the lead frame, effectively reducing the overall package size.

[0063] Furthermore, a package structure with exposed conductive units (i.e., a package structure with at least a portion of conductive units not covered by the package material, for example, the surface area of ​​the exposed conductive units is approximately greater than or equal to 1.2 times the back surface area of ​​the power device substrate) can achieve good bidirectional heat dissipation and improve component performance.

Claims

1. A packaging structure, characterized in that, include: A conductor frame; A power device includes a substrate, an active layer, a plurality of first electrodes, a plurality of second electrodes, and a third electrode. The active layer is disposed on the substrate, and the plurality of first electrodes, the plurality of second electrodes, and the third electrode are disposed on the active layer. The potentials of the plurality of first electrodes are different from the potentials of the plurality of second electrodes, and the plurality of first electrodes and the plurality of second electrodes are arranged in an alternating manner. Multiple first protrusions are disposed on each of the first electrodes; A plurality of second protrusions are disposed on each of the second electrodes, wherein the plurality of first protrusions and the plurality of second protrusions are connected to the lead frame; A conductive unit has a first portion, a second portion and an upper surface, wherein the first portion of the conductive unit is connected to the substrate of the power device and the second portion of the conductive unit is connected to the lead frame. as well as An encapsulation material covers the power device and the lead frame, with a portion of the upper surface of the conductive unit exposed by the encapsulation material.

2. The packaging structure as described in claim 1, characterized in that, This power device is a unidirectional power element.

3. The packaging structure as described in claim 1, characterized in that, The plurality of first electrodes include a source electrode, the plurality of second electrodes include a drain electrode, and the third electrode includes a gate electrode.

4. The packaging structure as described in claim 1, characterized in that, The plurality of first protrusions and the plurality of second protrusions are made of copper, tin, gold, or a combination thereof.

5. The packaging structure as described in claim 1, characterized in that, The plurality of first protrusions and the plurality of second protrusions have a diameter of at least 65 micrometers.

6. The packaging structure as described in claim 5, characterized in that, The plurality of first protrusions have a first spacing of at least 40 micrometers.

7. The packaging structure as described in claim 6, characterized in that, The spacing between the plurality of second protrusions is the same as the first spacing between the plurality of first protrusions.

8. The packaging structure as described in claim 6, characterized in that, The first spacing is less than or equal to the diameter of the plurality of first protrusions and the plurality of second protrusions.

9. The packaging structure as described in claim 6, characterized in that, The plurality of first protrusions and the plurality of second protrusions have a second spacing of at least 65 micrometers.

10. The packaging structure as described in claim 9, characterized in that, The second spacing is greater than or equal to 1.6 times the first spacing.

11. The packaging structure as described in claim 1, characterized in that, The substrate of the power device has a first surface area, and the portion of the upper surface of the conductive unit that exposes the encapsulation material has a second surface area, and the second surface area is greater than or equal to 1.2 times the first surface area.

12. The packaging structure as described in claim 5, characterized in that, It also includes multiple metal pads disposed between the conductor frame and the multiple first protrusions and the multiple second protrusions.

13. The packaging structure as described in claim 12, characterized in that, The plurality of metal pads are made of copper, silver, gold, tin, or combinations thereof.

14. The packaging structure as described in claim 12, characterized in that, The plurality of metal pads have a width that is less than or equal to the diameter of the plurality of first protrusions and the plurality of second protrusions.

15. The packaging structure as described in claim 1, characterized in that, The lead frame and the power device have a third spacing, which is at least 60 micrometers.

16. The packaging structure as described in claim 1, characterized in that, It also includes a patterned passivation layer covering the active layer and a portion of the plurality of first electrodes and the plurality of second electrodes.

17. The packaging structure as described in claim 16, characterized in that, It also includes a patterned polymer layer, which covers the patterned passivation layer and a portion of the plurality of first electrodes and the plurality of second electrodes to form a plurality of openings.

18. The packaging structure as described in claim 17, characterized in that, It also includes multiple metal layers disposed on the sidewalls and bottom of the multiple openings, and electrically connected to the multiple first electrodes and the multiple second electrodes.

19. The packaging structure as described in claim 18, characterized in that, The plurality of first protrusions and the plurality of second protrusions are connected to the plurality of first electrodes and the plurality of second electrodes through the plurality of metal layers.

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