QFN Package Structure and Its Manufacturing Method

Abstract

The present invention provides a QFN package structure and a manufacturing method thereof. The QFN package structure includes a package frame, a chip, and a plastic encapsulation layer. The package frame includes at least one base island and pins distributed around the base island. The chip is disposed on the base island and electrically connected to the pins via metal leads. The plastic encapsulation layer covers the package frame, chip, and metal leads. The package structure also includes at least one connector, each of which is fixedly connected to the pins and the base island to connect the pins to the base island. The connector provides fixed support for the inner pins, reducing the potential sagging of the inner pins during manufacturing and transportation. The connector also serves as a conductive transfer structure, reducing the length of some metal leads and resolving the problem of long arcs being difficult to bond.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic packaging, and in particular to a QFN packaging structure and a manufacturing method thereof. Background Art

[0002] With the development of technology, the requirements for the functional integration of chip packaging structures are becoming higher and higher. Therefore, many large-sized chip packaging structures have emerged. The large-sized QFN (Quad Flat No-leads) packaging structure has long internal pins and a half-etched internal pin design, which leads to a lack of support for the internal pins. During the manufacturing and transportation process, due to the gravity of the internal pins themselves, they are prone to sagging and cause wire collapse. Summary of the Invention

[0003] The object of the present invention is to provide a QFN packaging structure and a manufacturing method thereof.

[0004] The present invention provides a QFN package structure, which includes a package frame, a chip, and a plastic encapsulation layer. The package frame includes at least one base island and pins distributed around the base island. The chip is arranged on the base island and electrically connected to the pins through metal leads. The plastic encapsulation layer covers the package frame, the chip, and the metal leads. The structure further includes:

[0005] At least one connector is respectively connected and fixed to the pin and the base island, connecting the pin to the base island.

[0006] As a further improvement of the present invention, the pins are composed of inner pins on the inner side and outer pins on the outer side.

[0007] As a further improvement of the present invention, the connecting member includes a first side and a second side opposite to each other, the first side of the connecting member is arranged at the edge of the base island, and the second side of the connecting member is arranged at the inner pin.

[0008] As a further improvement of the present invention, the QFN packaging structure includes at least two connectors, and at least one connector is provided on two opposite sides of the base island respectively.

[0009] As a further improvement of the present invention, the QFN packaging structure further includes a connecting rib connecting different inner pins, and at least one of the connecting members is connected to the connecting rib.

[0010] As a further improvement of the present invention, the surface of the connector has a conductive area, the connector and the base island are insulated, and the connector and the inner pin are conductive.

[0011] As a further improvement of the present invention, the chip and the conductive area of the fixing member are electrically connected through the metal lead, and are electrically connected to the inner pin through the connecting member, or the conductive area and the inner pin are electrically connected through the metal lead.

[0012] As a further improvement of the present invention, the connector is a metal sheet, the surface of the metal sheet constitutes the conductive area, and the connector is fixed to the base island by bonding with non-conductive glue, and is fixed to the inner pin by bonding with conductive glue.

[0013] As a further improvement of the present invention, the connecting member is a second chip, which is fixed to the base island and the inner pins by adhesive, and a plurality of pads are provided on the surface of the second chip to form the conductive area.

[0014] As a further improvement of the present invention, the second chip is insulated from the base island and the inner pins, the conductive areas of the chip and the second chip are electrically connected through metal leads, and the conductive areas and the inner pins are electrically connected through metal leads.

[0015] As a further improvement of the present invention, the connecting member is an adapter plate, which is fixed to the base island and the inner pin by conductive adhesive. The adapter plate includes a dielectric layer and a metal circuit arranged therebetween, and the metal circuit constitutes a conductive area.

[0016] The present invention also provides a method for manufacturing a QFN package structure, comprising the steps of:

[0017] Providing a packaging frame and placing the chip on the base island of the packaging frame;

[0018] Leading metal leads between the chip and the inner pins of the packaging frame;

[0019] Connectors are provided between the base island and the inner pins of the packaging frame.

[0020] As a further improvement of the present invention, “providing a connector between the base island and the pins in the frame” specifically includes:

[0021] Disposing a metal sheet between the base island and the inner pins of the packaging frame;

[0022] The metal sheet is bonded and fixed to the inner pins through conductive glue, and the metal sheet is bonded and fixed to the base island through non-conductive glue.

[0023] As a further improvement of the present invention, the following steps are also included:

[0024] Metal leads are led between the chip and the metal sheet.

[0025] As a further improvement of the present invention, “providing a connector between the base island and the pins in the frame” specifically includes:

[0026] Disposing a second chip between the base island and the inner pins of the frame;

[0027] The second chip is bonded and fixed to the base island and the inner pins respectively by adhesive.

[0028] As a further improvement of the present invention, the following steps are also included:

[0029] A metal wire is led between the chip and the second chip pad, and a metal wire is led between the second chip pad and the inner pin.

[0030] As a further improvement of the present invention, “providing a connector between the base island and the pins in the frame” specifically includes:

[0031] An adapter plate is provided between the base island and the inner pins of the frame;

[0032] The adapter plate is bonded and fixed to the base island and the inner pins respectively through conductive glue.

[0033] As a further improvement of the present invention, the following steps are also included:

[0034] A metal lead is led between the chip and the metal circuit area of the adapter plate.

[0035] The beneficial effects of the present invention are as follows: the present invention provides a connector connecting the base island and the pin, and utilizes the connector to provide fixed support for the inner pin, thereby reducing the sagging problem that may occur in the inner pin during the manufacturing and transportation process, and the connector can be used as a conductive transfer structural component to reduce the length of some metal leads and solve the problem that long wire arcs cannot be connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the QFN packaging structure in Example 1 of the present invention.

[0037] Figure 2 This is a schematic diagram of the QFN packaging structure in Example 2 of the present invention.

[0038] Figure 3 This is a schematic diagram of the QFN package structure in Example 3 of the present invention

[0039] Figure 4 Schematic diagram of the manufacturing process of the QFN packaging structure in one embodiment of the present invention. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this application and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and are not to be construed as limiting the present invention.

[0042] For ease of explanation, this document uses terms that indicate spatial relative positions, such as "upper," "lower," "rear," "front," etc., to describe the relationship of one unit or feature shown in the drawings relative to another unit or feature. Terms that indicate spatial relative positions may include different orientations of the device during use or operation other than the orientation shown in the drawings. For example, if the device in the drawings is turned over, units described as being "below" or "above" other units or features will be located "below" or "above" the other units or features. Therefore, the exemplary term "below" can encompass both below and above spatial orientations.

[0043] Example 1

[0044] like Figure 1 As shown, embodiment 1 of the present invention provides a QFN package structure, which includes a package frame 1, a chip 2, and a plastic layer (not shown in the figure for ease of illustration). The package frame 1 includes at least one base island 11 and pins 12 distributed around the base island 11. In this embodiment, the package frame 1 includes a rectangular base island 11 and pins 12 arranged around the four sides of the base island 11. In other embodiments, multiple base islands can be provided according to the functional requirements of the package structure, and the pin position area can be adjusted accordingly.

[0045] The pins 12 are composed of inner pins 121 and outer pins 122 . The inner pins 121 are half-etched on the side away from the chip, while the outer pins 122 are solid.

[0046] Chip 2 is positioned at the center of island 11 and secured to island 11 using a conductive adhesive such as silver glue. Multiple pads 21 are located along the edges of chip 2. Metal leads 3 are soldered between pads 21 and inner pins 121, electrically connecting chip 2 to pins 12.

[0047] The plastic encapsulation layer is based on epoxy resin and is added with additives such as curing agent and coupling agent. It covers the packaging frame 1, chip 2 and metal lead 3 to protect the packaging structure from the influence of the external environment. Some external pins 122 are exposed on the side and / or bottom of the plastic encapsulation layer to serve as external pins of the QFN packaging structure.

[0048] The QFN package structure also includes at least one connector 4, which is respectively connected and fixed to the inner pin 121 and the base island 11, connecting the pin 12 to the base island 11. Connector 4 includes a first side 41 and a second side 42, with the first side of connector 4 positioned at the edge of the base island 11 and the second side of connector 4 positioned at the inner pin 121. Connector 4 has a high structural strength and can provide support and fixation for the inner pin 121, lifting it and preventing it from sagging during manufacturing and transportation, which could cause problems such as collapse of the metal lead 3.

[0049] Furthermore, the QFN package structure includes at least two connectors 4, with at least one connector 4 disposed on each of two opposing sides of the base island 11. Providing connectors 4 on opposing sides can make the force applied to the pins 12 around the base island 11 more uniform, thereby improving the overall stability of the pins 12. For example, in this embodiment, connectors 4 are disposed on two opposing sides of the base island 11. In other embodiments, for larger package frames 1, one connector 4 may be disposed on each of three or four sides, or multiple connectors 4 may be disposed on one or more sides to strengthen support for the internal pins 121.

[0050] Furthermore, a conductive area 43 is provided on the surface of the connector 4, the connector 4 and the base island 11 are insulated, the connector 4 and the inner pin 121 are conductively provided, the chip 2 and the conductive area 43 of the connector 4 are electrically connected through the metal lead 3, and are electrically connected to the pin 12 through the connector 4, or the conductive area 43 and the inner pin 121 are electrically connected through the metal lead 3, so that the connector 4 is used as a conductive transfer structure, which can reduce the length of the metal lead 3 and solve the problem that many long wire arcs cannot be wired.

[0051] Specifically, in Example 1, the connector 4 is a metal plate, such as an aluminum plate or copper plate with a certain thickness, which is conductive in itself, and the surface of the metal sheet as a whole constitutes a conductive area. The connector is fixed to the base island 11 by bonding with non-conductive glue to avoid short circuit, and is fixed to the inner pin by bonding with conductive glue to achieve electrical connection with the inner pin 121.

[0052] In this embodiment, the QFN package structure also includes a connecting rib 13 connecting different inner pins 121, and at least one connector 4 is connected to the connecting rib 13. The connecting rib 13 connects the pins of the same electrical nature, which can expand the wire bonding area of the pins of the same electrical nature, thereby providing multiple metal leads 3 on the connecting rib 13. Directly fixing the connector 4 to the connecting rib 13 can improve the support for the heavier connecting rib 13, and because the connecting rib 13 of a certain length has a long span between the inner pins 12, the direct connection of the connector 4 to it can also make the force distribution on the inner pins 121 more uniform. Exemplarily, in this embodiment, the package frame 1 has two connecting ribs 13, and a connector 4 is provided to connect to the connecting rib 13 respectively.

[0053] Example 2

[0054] like Figure 2 As shown, embodiment 2 of the present invention provides a QFN packaging structure, which is generally similar to embodiment 1, except that:

[0055] The connecting part 4 is a second chip, which is fixed to the base island 11 and the inner pin 121 by an adhesive. The multiple pads on its surface constitute a conductive area 43 for connection of the metal lead 3. In this embodiment, in addition to lifting the inner pin, the second chip also serves as a conductive transfer.

[0056] Furthermore, the second chip is insulated from the base island 11 and the inner pin 121. The chip 2 and the conductive area 43 of the second chip are electrically connected via the metal lead 3, and the conductive area 43 and the inner pin 121 are electrically connected via the metal lead 3. Thus, the second chip is used as a conductive transfer structure, which can reduce the length of the metal lead 3 and solve the problem that many long arcs cannot be wired.

[0057] Example 3

[0058] like Figure 3 As shown, embodiment 3 of the present invention provides a QFN packaging structure, which is generally similar to embodiment 1, except that:

[0059] Connector 4 is an adapter plate, a conductive structural support made of dielectric material. Metal traces and conductive metal vias are embedded within the dielectric layer, enabling electrical connectivity between the upper and lower surfaces of the adapter plate. The adapter plate is bonded to base island 11 and inner pins 121 using conductive adhesive. The metal traces on its upper surface form a conductive area 43 for connection to metal leads 3. The metal traces on its lower surface are electrically connected to inner pins 121 via conductive adhesive.

[0060] It is understandable that the specific material and structure of the connector 4 are not limited to the above embodiment, and other structural support members that can connect the inner pins 121 and the base island 11 and realize conductivity on the surface can be used as the connector 4.

[0061] The present invention also provides a method for manufacturing a QFN package structure, comprising the steps of:

[0062] S1: providing a packaging frame 1 and placing a chip 2 on the base island 11 of the packaging frame 1 .

[0063] S2: Lead metal wires 3 between the chip 2 and the pins 121 inside the package frame 1.

[0064] S3: Connectors 4 are provided between the base island 11 and the inner pins 121 of the packaging frame 1 .

[0065] Specifically, depending on the specific material used for the connector 4, step S3 may include:

[0066] S3a: placing a metal sheet between the base island 11 and the inner pin 121 of the package frame;

[0067] The metal sheet is fixed to the inner pin 121 by means of conductive glue, and the metal sheet is fixed to the base island 11 by means of non-conductive glue.

[0068] Furthermore, after step S3a, the method further includes the following steps:

[0069] Metal leads 3 are provided between the chip 2 and the metal sheet.

[0070] Alternatively, step S3 may further include:

[0071] S3b: placing a second chip between the base island 11 and the inner pin 121 of the package frame;

[0072] The second chip is bonded and fixed to the inner pins 121 and the base island 11 by adhesive.

[0073] Furthermore, after step S3b, the method further includes the following steps:

[0074] A metal lead 3 is led between the chip 2 and the second chip pad, and a metal lead 3 is led between the second chip pad and the inner pin 121 .

[0075] Alternatively, step S3 may further include:

[0076] S3c: Install an adapter plate between the base island 11 and the pins 121 in the package frame;

[0077] The adapter plate is bonded and fixed to the inner pins 121 and the base island 11 respectively through conductive glue.

[0078] Furthermore, after step S3c, the method further includes the following steps:

[0079] Metal leads 3 are led between the chip 2 and the metal circuit area of the transfer board.

[0080] To sum up, the present invention provides a connector that connects the base island to the pin, and uses the connector to fix and support the inner pin, thereby reducing the sagging problem that may occur in the inner pin during the manufacturing and transportation process. The connector can also serve as a conductive transfer structure to reduce the length of some metal leads and solve the problem that long wire arcs cannot be connected.

[0081] It should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0082] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A QFN package structure, comprising a package frame, a chip, and a plastic encapsulation layer, wherein the package frame comprises at least one base island and pins distributed around the base island, the chip is disposed on the base island and electrically connected to the pins via metal leads, and the plastic encapsulation layer covers the package frame, the chip, and the metal leads, characterized in that: The pins include inner pins on the inner side, and the QFN package structure further includes: At least one connector, the connector being respectively connected and fixed to the inner pin and the base island, connecting the inner pin and the base island; The surface of the connector has a conductive area, the connector and the base island are insulated, the connector and the inner pin are conductively configured, and the chip and the conductive area of the connector are electrically connected through the metal lead, and are electrically connected to the inner pin through the connector, or the conductive area and the inner pin are electrically connected through the metal lead.

2. The QFN package structure according to claim 1, wherein: The pins further include outer pins on the outside.

3. The QFN package structure according to claim 2, wherein: The connecting member includes a first side and a second side opposite to each other. The first side of the connecting member is arranged at the edge of the base island, and the second side of the connecting member is arranged at the inner pin.

4. The QFN package structure according to claim 3, wherein: The QFN package structure includes at least two connectors, and at least one connector is disposed on two opposite sides of the base island.

5. The QFN package structure according to claim 4, wherein: The QFN package structure further includes a connecting rib connecting different inner pins, and at least one of the connecting members is connected to the connecting rib.

6. The QFN package structure according to claim 4, wherein: The connecting member is a metal sheet, the surface of the metal sheet constitutes the conductive area, and the connecting member is fixed to the base island by bonding with non-conductive glue, and is fixed to the inner pin by bonding with conductive glue.

7. The QFN package structure according to claim 4, wherein: The connecting member is a second chip, which is fixed to the base island and the inner pins by adhesive. A plurality of pads are provided on the surface of the second chip to form the conductive area.

8. The QFN package structure according to claim 4, wherein: The connecting member is a transfer plate, which is fixed to the base island and the inner pin by means of conductive adhesive. The transfer plate includes a dielectric layer and a metal circuit arranged therebetween, and the metal circuit constitutes a conductive area.

9. A method for manufacturing a QFN package structure, characterized in that: Including steps: Providing a packaging frame and placing the chip on the base island of the packaging frame; Leading metal leads between the chip and the inner pins of the package frame; A connector is arranged between the base island and the inner pin of the packaging frame, and a conductive area is provided on the surface of the connector. The connector and the base island are insulated, and the connector and the inner pin are conductive. The chip and the conductive area of the connector are electrically connected through the metal lead, and are electrically connected to the inner pin through the connector, or the conductive area and the inner pin are electrically connected through the metal lead.

10. The method for manufacturing a QFN package structure according to claim 9, wherein: “Providing a connector between the base island and the inner pins of the packaging frame” specifically includes: Disposing a metal sheet between the base island and the inner pins of the packaging frame; The metal sheet is bonded and fixed to the inner pins through conductive glue, and the metal sheet is bonded and fixed to the base island through non-conductive glue.

11. The method for manufacturing a QFN package structure according to claim 9, wherein: “Providing a connector between the base island and the inner pins of the packaging frame” specifically includes: Disposing a second chip between the base island and the inner pins of the packaging frame; The second chip is bonded and fixed to the base island and the inner pins respectively by adhesive.

12. The method for manufacturing a QFN package structure according to claim 11, wherein: Also includes the steps: Metal wires are led between the chip and the bonding pad of the second chip, and metal wires are led between the bonding pad of the second chip and the inner pins.

13. The method for manufacturing a QFN package structure according to claim 9, wherein: “Providing a connector between the base island and the inner pins of the packaging frame” specifically includes: An adapter plate is provided between the base island and the inner pins of the packaging frame; The adapter plate is bonded and fixed to the base island and the inner pins respectively through conductive glue.

14. The method for manufacturing a QFN package structure according to claim 13, wherein: Also includes the steps: Metal leads are led between the chip and the metal circuit area of the adapter board.

Images