CN117855180A

CN117855180A - Package structure and method for forming the same

Info

Publication number: CN117855180A
Application number: CN202311653296.2A
Authority: CN
Inventors: 徐赛; 刘恺; 刘红军; 王赵云; 李慧颖
Original assignee: JCET Group Co Ltd
Current assignee: JCET Group Co Ltd
Priority date: 2023-12-04
Filing date: 2023-12-04
Publication date: 2024-04-09

Abstract

The application provides a packaging structure and a forming method thereof. The package structure includes: the central area of the top surface of the base island is supported with a chip; lead frame, set up in the periphery of base island, lead frame includes: the bottom surface of the pin is welded to the top surface of the base island, and the first end of the metal column protrudes out of the pin and is coplanar with the bottom surface of the base island; a bonding wire connecting the chip and the pins; the plastic package body is used for coating the base island, the lead frame, the chip and the bonding wires, the bottom surface of the plastic package body exposes the end surface of the first end of the metal column, and the top surface of the plastic package body exposes the end surface of the second end of the metal column. According to the technical scheme, the problems that the heat dissipation speed of the packaging structure is low and the number of pins is limited due to space limitation of the lead frame can be avoided.

Description

Package structure and method for forming the same

Technical Field

The present disclosure relates to semiconductor manufacturing, and more particularly, to a package structure and a method for forming the same.

Background

Quad Flat No-leads Package (QFN) is a Quad Flat No-lead Package, and has a square or rectangular shape, a large area of exposed land at the center of the bottom of the Package for conducting heat, and pins for electrical connection around the periphery of the Package with large pads. QFN packages provide excellent electrical performance because they do not have gull-wing leads, as conventional small outline integrated circuit (Small Outline Integrated Circuit, abbreviated SOIC) packages and thin small size packages (Thin Small Outline Package, abbreviated TSOP) packages, have short conductive paths between the inner leads and the bond pads, and low self inductance and wiring resistance within the package.

However, the conventional quad flat package has a relatively single heat dissipation path, and thus has a relatively low heat dissipation rate because it can only dissipate heat by means of the back surface of the land located at the center of the bottom of the package, and the heat dissipation area thereof is small. And since the lead frame of the conventional quad flat package requires a sufficient space for disposing the connection bars to support the base island, the number of pins is limited.

Therefore, providing a package structure capable of fast heat dissipation without limiting the number of pins and a method for forming the same are technical problems to be solved.

Disclosure of Invention

The technical problem to be solved in the application is to provide a packaging structure and a forming method thereof, so as to avoid the problems of low heat dissipation speed of the packaging structure and limited pin quantity caused by space limitation of a lead frame.

In order to solve the above-mentioned problem, the present application provides a package structure, including: the central area of the top surface of the base island is supported with a chip; lead frame, set up in the periphery of base island, lead frame includes: the bottom surface of the pin is welded to the top surface of the base island, the first end of the metal column protrudes out of the bottom surface of the pin and is coplanar with the bottom surface of the base island, and the second end of the metal column protrudes out of the top surface of the pin; a bonding wire connecting the chip and the pins; the plastic package body is used for coating the base island, the lead frame, the chip and the bonding wires, the bottom surface of the plastic package body exposes the end surface of the first end of the metal column, and the top surface of the plastic package body exposes the end surface of the second end of the metal column.

In some embodiments, the bottom surface of the pin is flush with the top surface of the island or the bottom surface of the pin is higher than the top surface of the island.

In some embodiments, the portion of the pin between the metal post and the chip is soldered to the top surface of the island.

In some embodiments, the islands are different from the thickness of the pins.

In some embodiments, the bottom surface of the pin is soldered to the outer edge region of the top surface of the base island by a first solder layer, and the chip is soldered to the central region of the top surface of the base island by a second solder layer.

In some embodiments, the outer edge region of the base island is provided with a through hole, the lead frame is arranged above the outer edge region of the base island, the first end of the metal post penetrates through the through hole, and the bottom surface of the pin is welded to the outer edge region of the top surface of the base island.

In some embodiments, the through holes are in one-to-one correspondence with the metal posts.

In some embodiments, each of the vias corresponds to two or more of the metal posts.

In some embodiments, the region of the island in contact with the leadframe has an insulating protective layer.

In order to solve the above problem, the present application further provides a method for forming a package structure, the method including: providing a base island and a lead frame arranged on the periphery of the base island, wherein the lead frame comprises: mutually perpendicular metal columns and pins; welding the bottom surface of the pin to the top surface of the base island, wherein the first end of the metal post protrudes out of the bottom surface of the pin and is coplanar with the bottom surface of the base island, and the second end of the metal post protrudes out of the top surface of the pin; welding a chip on the central area of the top surface of the base island; the chip and the pins are connected through bonding wires; and filling a plastic packaging material between the base island and the lead frame to form a plastic packaging body which is used for coating the base island, the lead frame, the chip and the bonding wires, wherein the bottom surface of the plastic packaging body exposes the end surface of the first end of the metal column, and the top surface of the plastic packaging body exposes the end surface of the second end of the metal column.

In some embodiments, the step of soldering the bottom surface of the pin to the top surface of the island, the first end of the metal post protruding from the pin and being coplanar with the bottom surface of the island further comprises: and forming a first welding layer on the outer edge area of the top surface of the base island, and welding the pins on the outer edge area of the top surface of the base island.

In some embodiments, the step of bonding a die to the central region of the top surface of the submount further comprises: and forming a second welding layer in the central area of the top surface of the base island, and welding the chip to the central area of the top surface of the base island.

In some embodiments, the step of providing a base island further comprises: providing a base island with a through hole in the outer edge area; the step of soldering the bottom surface of the pin to the top surface of the island includes: the lead frame is arranged above the outer edge area of the base island; and enabling the first end of the metal column to pass through the through hole, and welding the bottom surface of the pin to the outer edge area of the top surface of the base island.

In some embodiments, the step of providing a land with a through hole in an outer edge region further comprises: forming an insulating protection layer in a region where the base island is required to be contacted with the lead frame; the step of passing the first end of the metal post through the through hole and welding the bottom surface of the pin to the outer edge region of the top surface of the base island comprises the following steps: the insulating protection layer is positioned at the contact area of the base island and the lead frame.

According to the technical scheme, the mutually perpendicular metal columns and the pins are arranged on the lead frame, the problem that the number of the pins is limited due to space limitation of the lead frame is solved, the size of the base island can be the same as that of the packaging body without limitation of the lead frame, meanwhile, the end face of the first end and the end face of the second end of the metal columns are exposed to the plastic packaging body, the heat dissipation area of the packaging structure is increased, and the heat dissipation speed of the packaging structure is accelerated.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly explain the drawings needed in the embodiments of the present application, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a side cross-sectional view of a package structure in a first embodiment of the present application;

FIG. 2 is a top view of a package structure according to a first embodiment of the present application;

FIG. 3 is a top view of a submount in a second embodiment of the present application;

part (a) in fig. 4 is a top view of the insulating protective layer in the second embodiment of the present application, and part (b) is a side view of the insulating protective layer in the second embodiment of the present application. The method comprises the steps of carrying out a first treatment on the surface of the

FIG. 5 is a schematic diagram illustrating steps of a method for forming a package structure according to a first embodiment of the present application;

FIGS. 6 to 9 are schematic views of a device structure formed by main steps in the first embodiment of the present application;

fig. 10 is a schematic view of a device structure formed by main steps in the first embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.

In order to solve the problems of low heat dissipation speed of a packaging structure and limited pin quantity caused by space limitation of a lead frame in the prior art, embodiments of the present application provide a packaging structure and a forming method thereof.

The following first describes a package structure provided in an embodiment of the present application.

FIG. 1 is a side cross-sectional view of a package structure in a first embodiment of the present application; fig. 2 is a top view of a package structure according to a first embodiment of the present application. Referring to fig. 1 and fig. 2 together, the package structure of the present embodiment includes: the semiconductor packaging structure comprises a base island 11, a lead frame 12, bonding wires 13 and a plastic package body 14, wherein the lead frame 12, the bonding wires 13 and the plastic package body 14 are arranged on the periphery of the base island 11, and a chip 15 is supported in the central area of the top surface of the base island 11; the lead frame 12 includes: the bottom surface of the pin 22 is welded to the top surface of the base island 11, a first end of the metal column 21 protrudes out of the bottom surface of the pin 22 and is coplanar with the bottom surface of the base island 11, and a second end of the metal column 21 protrudes out of the top surface of the pin 22; the bonding wire 13 connects the chip 15 and the pin 22; the plastic package body 14 encapsulates the base island 11, the lead frame 12, the chip 15 and the bonding wires 13, the bottom surface of the plastic package body 14 exposes the end surface of the first end of the metal pillar 21, and the top surface of the plastic package body 14 exposes the end surface of the second end of the metal pillar 21.

Referring to fig. 1, in the present embodiment, the metal posts 21 and the pins 22 are cross-shaped, and the metal posts 21 and the pins 22 are integrally formed, so as to avoid collapse of the metal posts 21 on the lead frame 12.

With continued reference to fig. 1, in this embodiment, the bottom surfaces of the pins 22 are flush with the top surface of the base island 11, so that the pins 22 are more attached to the base island 11, thereby reducing the thickness of the plastic package 14 and further reducing the volume of the package structure. In other embodiments, the bottom surface of the pins 22 is higher than the top surface of the islands 11.

With continued reference to fig. 1, in this embodiment, the portion of the pin 22 between the metal pillar 21 and the chip 15 is soldered to the top surface of the island 11. The islands 11 are of a different thickness than the pins 22. The bottom surface of the pin 22 is soldered to the outer edge region of the top surface of the base island 11 through a first solder layer 31, and the chip 15 is soldered to the central region of the top surface of the base island 11 through a second solder layer 32. The material of the first solder layer 31 is non-conductive glue to ensure insulation between the pins 22 and the islands 11; the material of the second solder layer 32 is conductive adhesive, so as to realize electrical connection between the chip 15 and the island 11.

Referring now to fig. 3, therein is shown a top view of a submount according to a second embodiment of the present application. In this embodiment, the outer edge region of the base island 11 is provided with a through hole 16, the lead frame 12 is disposed above the outer edge region of the base island 11, the first end of the metal post 21 passes through the through hole 16, and the bottom surface of the pin 22 is welded to the outer edge region of the top surface of the base island 11.

Referring now to fig. 4, where part (a) in fig. 4 is a top view of the insulating protection layer according to the second embodiment of the present application, and part (b) in fig. 4 is a side view of the insulating protection layer according to the second embodiment of the present application. In this embodiment, the region of the island 11 in contact with the lead frame 12 has an insulating protective layer 17. The insulating protection layer 17 is used for insulating and isolating the base island 11 from the lead frame 12. Specifically, the insulating protection layer 17 is located at the outer edge of the base island and the inner wall of the through hole, so as to insulate the base island 11 from the lead frame 12.

According to the technical scheme, the problem that the number of pins 22 is limited due to the space limitation of the lead frame 12 is solved by arranging the metal columns 21 and the pins 22 which are perpendicular to each other on the lead frame 12, meanwhile, the size of the base island 11 can be the same as that of the package body without being limited by the lead frame 12, and the end face of the first end of the metal column 21, the end face of the second end and the bottom face of the base island 11 are exposed to the plastic package body 14, so that the heat dissipation area of the package structure is greatly increased, and the heat dissipation speed of the package structure is accelerated.

In some embodiments, each through hole 16 may correspond to two or more metal posts 21, i.e., two or more metal posts 21 may be inserted into one through hole 16; in still other embodiments, a portion of the through-holes 16 corresponds to one metal post 21, and a portion of the through-holes 16 corresponds to two or more metal posts 21, i.e., a portion of the through-holes 16 has one metal post inserted therein, and a portion of the through-holes 16 has two or more metal posts 21 inserted therein.

Based on the same inventive concept, the application also provides a forming method of the packaging structure.

Referring now to fig. 5, therein is shown a schematic illustration of steps of a method for forming a package structure according to a first embodiment of the present disclosure, where the formed package structure is shown in fig. 1. The forming method of the packaging structure comprises the following steps: step S51, providing a base island and a lead frame disposed at the periphery of the base island, wherein the lead frame comprises: mutually perpendicular metal columns and pins; step S52, welding the bottom surface of the pin to the top surface of the base island, wherein the first end of the metal post protrudes out of the bottom surface of the pin and is coplanar with the bottom surface of the base island, and the second end of the metal post protrudes out of the top surface of the pin; step S53, welding a chip on the central area of the top surface of the base island; step S54, connecting the chip and the pins through bonding wires; and step S55, filling a plastic packaging material between the base island and the lead frame to form a plastic packaging body which is used for coating the base island, the lead frame, the chip and the bonding wires, wherein the bottom surface of the plastic packaging body exposes the end surface of the first end of the metal column, and the top surface of the plastic packaging body exposes the end surface of the second end of the metal column.

Fig. 6 to 9 are schematic structural views of the first embodiment of the present application.

Referring to step S51 and fig. 6, a base island 11 and a lead frame 12 disposed on the periphery of the base island 11 are provided, wherein the lead frame 12 includes: metal posts 21 and pins 22 are perpendicular to each other. In this embodiment, the metal posts 21 and the pins 22 are cross-shaped, and the metal posts 21 and the pins 22 are integrally formed, so as to avoid collapse of the metal posts 21 on the lead frame 12.

Referring to the step S52 and fig. 7, in this embodiment, the step of soldering the bottom surface of the pin 22 to the top surface of the island 11, and the step of protruding the first end of the metal pillar 21 from the pin 22 and being coplanar with the bottom surface of the island 11 further includes: a first solder layer 31 is formed on the outer edge region of the top surface of the base island 11, and the pins 22 are soldered to the outer edge region of the top surface of the base island 11. The material of the first solder layer 31 is non-conductive glue to ensure insulation between the pins 22 and the islands 11.

Referring to the step S53 and fig. 8, in this embodiment, the step of soldering a chip 15 to the central area of the top surface of the base island 11 further includes: a second solder layer 32 is formed on the central region of the top surface of the base island 11, and the chip 15 is soldered to the central region of the top surface of the base island 11. The material of the second solder layer 32 is conductive adhesive, so as to realize electrical connection between the chip 15 and the island 11.

Referring to step S54 and fig. 9, in the present embodiment, the chip 15 and the pins 22 are connected by bonding wires 13. The material of the bonding wire 13 may be gold, aluminum or copper.

Referring to step S55 and fig. 1, in this embodiment, a molding material is filled between the base island 11 and the lead frame 12 to form a molding body 14 covering the base island 11, the lead frame 12, the chip 15 and the bonding wires 13, wherein a bottom surface of the molding body 14 exposes an end surface of the first end of the metal pillar 21, and a top surface of the molding body 14 exposes an end surface of the second end of the metal pillar 21.

According to the technical scheme, the problem that the number of pins 22 is limited due to space limitation of the lead frame 14 is solved by arranging the metal columns 21 and the pins 22 which are perpendicular to each other on the lead frame 14, and the end faces of the first end and the second end of the metal columns 21 are exposed to the plastic package body 14, so that the heat dissipation area of the package structure is increased, and the heat dissipation speed of the package structure is accelerated.

Fig. 10 is a schematic structural diagram of the second embodiment of the present application. Referring to the following steps S51, S52 and fig. 10, in this embodiment, the step of providing a base island 11 further includes: providing a base island 11 with a through hole 16 in the outer edge area; the step of soldering the bottom surface of the pin 22 to the top surface of the island 11 includes: the lead frame 12 is arranged above the outer edge region of the base island 11; the first end of the metal post 21 is passed through the through hole 16, and the bottom surface of the pin 22 is soldered to the outer edge region of the top surface of the island 11.

Referring to step S51, fig. 3 and fig. 4, in this embodiment, the step of providing the island 11 with a through hole in an outer edge region further includes: forming an insulating protection layer 17 in a region where the island 11 needs to be in contact with the lead frame 12; the step of passing the first end of the metal post 21 through the through hole 16 and soldering the bottom surface of the pin 22 to the outer edge region of the top surface of the land 11 is as follows: the insulating protection layer 17 is located at a region where the island 11 contacts the lead frame 12. The insulating protection layer 17 is used for insulating and isolating the base island 11 from the lead frame 12.

According to the technical scheme, the through holes 16 are formed in the outer edge area of the base island 11, so that the lead frame 12 with the metal posts 21 is conveniently assembled on the base island 11, and the stability of the packaging structure is improved.

It should be noted that in this document, relational terms such as "first" and "second" are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the statement "comprises" and "comprising" does not exclude the presence of other elements than those listed in any process, method, article, or apparatus that comprises the element.

In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for the second embodiment, since it is substantially similar to the first embodiment, the description is relatively simple, and reference is made to the partial description of the first embodiment for the matters.

The foregoing is merely a preferred embodiment of the present application and is not intended to limit the scope of the present application. It should be noted that, for a person skilled in the art, several improvements and modifications can be made without departing from the principle of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A package structure, comprising:

the central area of the top surface of the base island is supported with a chip;

lead frame, set up in the periphery of base island, lead frame includes: the bottom surface of the pin is welded to the top surface of the base island, the first end of the metal column protrudes out of the bottom surface of the pin and is coplanar with the bottom surface of the base island, and the second end of the metal column protrudes out of the top surface of the pin;

a bonding wire connecting the chip and the pins;

the plastic package body is used for coating the base island, the lead frame, the chip and the bonding wires, the bottom surface of the plastic package body exposes the end surface of the first end of the metal column, and the top surface of the plastic package body exposes the end surface of the second end of the metal column.

2. The package structure of claim 1, wherein the bottom surface of the pin is flush with the top surface of the base island or the bottom surface of the pin is higher than the top surface of the base island.

3. The package structure of claim 1, wherein a portion of the pin between the metal pillar and the chip is soldered to a top surface of the submount.

4. The package structure of claim 1, wherein the base island is different from the pin thickness.

5. The package structure of claim 1, wherein the bottom surface of the pin is soldered to an outer edge region of the top surface of the base island by a first solder layer, and the chip is soldered to a center region of the top surface of the base island by a second solder layer.

6. The package structure according to claim 1, wherein the outer edge region of the base island is provided with a through hole, the lead frame is disposed above the outer edge region of the base island, and the first end of the metal post passes through the through hole, and the bottom surface of the pin is soldered to the outer edge region of the top surface of the base island.

7. The package structure of claim 6, wherein the through holes are in one-to-one correspondence with the metal posts.

8. The package structure of claim 6, wherein each of the through holes corresponds to two or more of the metal posts.

9. The package structure of claim 6, wherein the area of the island in contact with the leadframe has an insulating protective layer.

10. A method of forming a package structure, the method comprising:

providing a base island and a lead frame arranged on the periphery of the base island, wherein the lead frame comprises: mutually perpendicular metal columns and pins;

welding the bottom surface of the pin to the top surface of the base island, wherein the first end of the metal post protrudes out of the bottom surface of the pin and is coplanar with the bottom surface of the base island, and the second end of the metal post protrudes out of the top surface of the pin;

welding a chip on the central area of the top surface of the base island;

the chip and the pins are connected through bonding wires;

and filling a plastic packaging material between the base island and the lead frame to form a plastic packaging body which is used for coating the base island, the lead frame, the chip and the bonding wires, wherein the bottom surface of the plastic packaging body exposes the end surface of the first end of the metal column, and the top surface of the plastic packaging body exposes the end surface of the second end of the metal column.

11. The method of claim 10, wherein the step of soldering the bottom surface of the pin to the top surface of the island, the first end of the metal post protruding from the pin and being coplanar with the bottom surface of the island further comprises: and forming a first welding layer on the outer edge area of the top surface of the base island, and welding the pins on the outer edge area of the top surface of the base island.

12. The method of claim 10, wherein the step of bonding a die to the central region of the top surface of the submount further comprises: and forming a second welding layer in the central area of the top surface of the base island, and welding the chip to the central area of the top surface of the base island.

13. The method of claim 10, wherein the step of providing a base island further comprises: providing a base island with a through hole in the outer edge area; the step of soldering the bottom surface of the pin to the top surface of the island includes: the lead frame is arranged above the outer edge area of the base island; and enabling the first end of the metal column to pass through the through hole, and welding the bottom surface of the pin to the outer edge area of the top surface of the base island.

14. The method of claim 13, wherein the step of providing a land with a peripheral region provided with a through hole further comprises: forming an insulating protection layer in a region where the base island is required to be contacted with the lead frame; the step of passing the first end of the metal post through the through hole and welding the bottom surface of the pin to the outer edge region of the top surface of the base island comprises the following steps: the insulating protection layer is positioned at the contact area of the base island and the lead frame.