QFN packaging structure and manufacturing method thereof

Abstract

The present invention provides a QFN packaging structure and a manufacturing method thereof. The QFN packaging structure includes a packaging frame, a chip and a plastic sealing layer. The packaging 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 sealing layer covers the packaging frame, the chip and the metal leads. The QFN packaging structure also includes: at least one fixed sheet arranged on the base island; each fixed sheet is provided with at least one connecting belt, the connecting belt includes a first end respectively arranged on the fixed sheet and a second end arranged at the pin, and the connecting belt connects the base island and the pin. By arranging the fixed sheet on the base island and arranging the connecting belt connected to the pin on the fixed sheet, the connecting belt plays a role of fixing and supporting the pin, thereby reducing the sagging problem that may occur in the manufacturing and transportation process of the pin, and the fixed sheet can be used as a conductive transfer structural member to reduce the line length of some metal leads, and solve the problem that long arcs cannot be wired.

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 longer 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 packaging layer, wherein 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 is electrically connected to the pins through metal leads, the plastic packaging layer covers the package frame, the chip and the metal leads, and further includes:

[0005] At least one fixing plate disposed on the base island;

[0006] At least one connection belt is arranged on each fixing plate, and the connection belt comprises a first end respectively arranged on the fixing plate and a second end arranged at the tube pin, and the connection belt connects the base island and the tube pin.

[0007] 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, and the inner pins are half-etched on a side away from the chip.

[0008] As a further improvement of the present invention, the fixing plate is arranged adjacent to the edge of the base island, the connecting belt and the metal lead are arranged in parallel, and the second end of the connecting belt is connected to the inner pin close to the fixing plate.

[0009] As a further improvement of the present invention, the QFN packaging structure includes at least two fixing plates, and at least one fixing plate is disposed on two opposite sides of the base island, respectively.

[0010] As a further improvement of the present invention, the fixing sheet includes a fixing layer, a conductive layer and an insulating layer arranged between the fixing layer and the conductive layer, and the fixing sheet is fixedly bonded to the base island via the fixing layer.

[0011] As a further improvement of the present invention, the fixing layer and the conductive layer are copper layers, and the insulating layer is an insulating resin layer arranged between two copper layers.

[0012] 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 second end of the connecting strip is connected to the connecting rib.

[0013] As a further improvement of the present invention, the connecting strip is a conductive metal strip.

[0014] As a further improvement of the present invention, the chip and the conductive layer of the fixing plate are electrically connected through the metal lead, and are electrically connected to the pin through the conductive metal strip.

[0015] As a further improvement of the present invention, the conductive metal strip is an aluminum strip or an aluminum wire.

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

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

[0018] fixing at least one fixing sheet to the base island;

[0019] Leading metal leads between the chip and the inner pins of the packaging frame;

[0020] A connecting belt is arranged between the fixing plate and the inner pin of the frame.

[0021] As a further improvement of the present invention, “fixing at least one fixing sheet on the base island” specifically includes:

[0022] Bonding two layers of copper sheets by insulating resin glue to form a fixed sheet;

[0023] At least two of the fixing plates are fixed at the edge of the base island, and at least one fixing plate is respectively arranged on two opposite sides of the base island.

[0024] As a further improvement of the present invention, the steps are also included:

[0025] Metal leads are led between the chip and the fixing sheet.

[0026] The beneficial effects of the present invention are as follows: a fixing plate is arranged on the base island, and a connecting belt connected to the inner pin is arranged on the fixing plate, and the connecting belt is used to fix and support the inner pin, thereby reducing the sagging problem that may occur in the manufacturing and transportation process of the inner pin, and the fixing plate can be used as a conductive transfer structure to reduce the length of some metal leads, thereby solving the problem that long wire arcs cannot be wired. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a QFN packaging structure in one embodiment of the present invention.

[0028] Figure 2 It is a side view of a fixing plate in one embodiment of the present invention.

[0029] Figure 3 It is a schematic diagram of the manufacturing process of the QFN packaging structure in one embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in combination with the specific implementation methods of this application and the corresponding drawings. Obviously, the described implementation methods are only part of the implementation methods of this application, not all of the implementation methods. Based on the implementation methods in this application, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] The embodiments of the present invention are described in detail below, and 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 cannot be understood as limiting the present invention.

[0032] For ease of explanation, this document uses terms that represent relative positions in space for description, such as "above", "below", "back", "front", etc., to describe the relationship of one unit or feature shown in the drawings relative to another unit or feature. Terms of relative positions in space can include different orientations of the device in use or operation other than the orientation shown in the figure. For example, if the device in the figure is turned over, the unit 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 the spatial orientations of below and above.

[0033] like Figure 1 As shown, the present invention provides a QFN package structure, which includes a package frame 1, a chip 2 and a plastic packaging layer (not shown in the figure for the convenience of explaining the structure). 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 on the four sides of the base island 11. In other embodiments, multiple base islands can be set according to the functional requirements of the package structure, and the pin position area can be adjusted accordingly.

[0034] The pin 12 is composed of an inner pin 121 and an outer pin 122. The inner pin 121 is half-etched on a side away from the chip, and the outer pin 122 is solid.

[0035] The chip 2 is arranged at the center of the base island 11 and is fixed to the base island 11 by means of conductive adhesive such as conductive silver adhesive. A plurality of pads 21 are arranged at the edge of the chip 2, and metal leads 3 are welded between the pads 21 of the chip 2 and the inner pins 121, so that the chip 2 is electrically connected to the pins 12.

[0036] 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 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.

[0037] The QFN package structure also includes at least one fixing sheet 4 disposed on the base island 11, and at least one connecting belt 5 is disposed on each fixing sheet 4. The connecting belt 5 includes a first end disposed on the fixing sheet 4 and a second end disposed at the inner pin 121, and the connecting belt 5 connects the inner pin 121 and the base island 11. The connecting belt 5 has a certain structural strength, and connects the inner pin 121 and the base island 11 respectively, and can play a role in fixing and supporting the inner pin 121, and pull the inner pin 121 to prevent it from sagging during the manufacturing and transportation process, thereby causing problems such as collapse of the metal lead 3.

[0038] The fixing plate 4 is arranged on the base island 11, and serves as a connecting piece between the connecting belt 5 and the base island 11. The fixing plate 4 is arranged near the edge of the base island 11, so as to reduce the required length of the connecting belt 5. The shorter connecting belt 5 has a higher structural strength than the longer connecting belt 5, thereby strengthening the fixing and supporting effect of the connecting belt 5 on the inner pin 121.

[0039] Further, the QFN package structure includes at least two fixing plates 4, and at least one fixing plate 4 is respectively arranged on two opposite sides of the base island 11. The fixing plates 4 are respectively arranged on the two opposite sides, and the corresponding connecting strips 5 are arranged, so that the force on the pins 12 around the base island 11 is more uniform, thereby improving the stability of the pins 12 as a whole. Exemplarily, in this embodiment, fixing plates 4 are respectively arranged at two opposite sides of the base island 11. In other embodiments, for a package frame 1 with a larger size, a fixing plate 4 can also be arranged at three sides or four sides, or multiple fixing plates 4 can be arranged on one or several sides to strengthen the support for the inner pins 121.

[0040] Furthermore, in this embodiment, the fixing sheet 4 is a composite multilayer structure, which includes a fixing layer 41, a conductive layer 42 and an insulating layer 43 disposed between the fixing layer 41 and the conductive layer 42, and the fixing sheet 4 is fixedly bonded to the base island 11 via the fixing layer 41.

[0041] Specifically, the fixed layer 41 and the conductive layer 42 are copper layers, and the insulating layer 43 is an insulating resin layer arranged between the two copper layers. Among them, the fixed layer 41 and the base island 11 are fixedly bonded by an adhesive material such as conductive glue. Using copper as its material can strengthen the bonding strength between the fixed plate 4 and the base island 11 and improve its reliability. In other embodiments, the fixed layer 41 can also be made of other sheet materials, and there is no strict restriction on this. The copper layer conductive layer 42 on the surface allows the fixed plate 4 to also play a role in transmitting electrical signals, thereby making it a conductive transfer structure for the metal lead 3. In other embodiments, the conductive layer 42 can also be made of other metal materials with excellent conductive properties. Since it is necessary to avoid a short circuit between the metal lead 3 and the base island 11, an insulating layer 43 is arranged between the fixed layer 41 and the conductive layer 42. In this embodiment, the insulating layer 43 is an insulating resin layer that also plays a bonding and fixing role. While insulating, it can effectively fix the conductive layer 42 and the fixed layer 41. In addition, since the insulating layer 43 is built into the fixing sheet 4, during the manufacturing process, the fixing sheet 4 and the chip 2 can be fixed to the base island 11 by adhesive material in the same process, which is time-saving, convenient and easy to implement.

[0042] In other embodiments of the present invention, the fixing sheet 4 may also be provided with only the conductive layer 42 , and the conductive layer 42 is directly fixed to the base island 11 by bonding with a non-conductive adhesive.

[0043] The connecting strip 5 and the metal lead 3 are arranged in parallel, and the second end of the connecting strip 5 is connected to the inner pin 121 close to the fixing plate 4 to avoid interference between the connecting strip 5 and the metal lead 3 and reduce the reliability of the packaging structure.

[0044] Furthermore, a plurality of connecting straps 5 may be provided on each fixing sheet 4, and the plurality of connecting straps 5 may further strengthen the lifting and fixing effect on the inner pins 121. In this embodiment, three connecting straps 5 are provided on each fixing sheet 4. In other embodiments, the number of connecting straps 5 may also be adjusted according to the size of the packaging frame 1.

[0045] Furthermore, the connecting band 5 is a conductive metal band, and the conductive layer 42 of the chip 2 and the fixing plate 4 are electrically connected through the metal lead 3, and is electrically connected to the pin 12 through the connecting band 5. Therefore, the fixing plate 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.

[0046] Specifically, the conductive metal strip is an aluminum strip or aluminum wire, which is wider than the metal lead 3 and has a certain structural strength, and can effectively fix and support the inner pin 121. In other embodiments, a thick copper strip or the like can also be used, as long as it is a good conductive metal strip with a certain structural strength.

[0047] In this embodiment, the QFN package structure also includes a connecting rib 13 connecting different inner pins 121, and at least one second end of a connecting strip 5 is connected to the connecting rib 13. The connecting rib 13 connects the pins of the same electrical nature, and can expand the wire bonding area of ​​the pins of the same electrical nature, so that a plurality of metal leads 3 are arranged on the connecting rib 13. Directly fixing the connecting strip 5 on the connecting rib 13 can improve the supporting effect of the connecting rib 13 with a larger weight, and because the connecting rib 13 with a certain length has a longer span between the inner pins 121, the connecting strip 5 is directly connected thereto, and the force distribution on the inner pins 121 can also be more uniform. Exemplarily, in this embodiment, the package frame 1 has two connecting ribs 13, and three connecting strips 5 are respectively arranged on each fixing plate 4 to connect to the connecting rib 13.

[0048] The present invention also provides a method for manufacturing a QFN packaging structure, comprising the steps of:

[0049] S1: providing a packaging frame 1 and placing a chip 2 on a base island 11 of the packaging frame 1 .

[0050] S2: Fix at least one fixing sheet 4 on the base island 11 .

[0051] Step S2 specifically includes:

[0052] The two layers of copper sheets are bonded together by insulating resin glue to form a fixing sheet 4;

[0053] At least two fixing plates 4 are fixed to the edge of the base island 11 by means of conductive adhesive, and at least one fixing plate 4 is disposed on two opposite sides of the base island 11 .

[0054] It should be noted that step S2 and the step S1 of "placing the chip 2 on the base island 11 of the packaging frame 1" can be performed simultaneously or in steps, and the order of the steps can be specifically adjusted according to production needs.

[0055] S3: Lead metal leads 3 between the chip 2 and the pins 121 inside the package frame 1.

[0056] S4: A connection strip 5 is provided between the fixing piece 4 and the pin 121 in the frame.

[0057] Specifically, the connecting strip 5 is a conductive metal strip.

[0058] Furthermore, in some embodiments of the present invention, after step S4, the following steps are also included:

[0059] Metal leads 3 are provided between the chip and the fixing plate.

[0060] In summary, the present invention arranges a fixing plate on the base island, and arranges a connecting belt connected to the inner pin on the fixing plate, and utilizes the connecting belt to fix and support the inner pin, thereby reducing the sagging problem that may occur in the manufacturing and transportation process of the inner pin, and the fixing plate can be used as a conductive transfer structure to reduce the length of some metal leads, thereby solving the problem that long wire arcs cannot be wired.

[0061] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description 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 mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0062] 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. All 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 packaging layer, wherein the package frame comprises at least one base island and pins distributed around the base island, the chip is arranged on the base island and is electrically connected to the pins through metal leads, and the plastic packaging layer covers the package frame, the chip and the metal leads, characterized in that: Also includes: At least one fixing plate disposed on the base island; At least one connecting belt is arranged on each fixing plate, the connecting belt comprises a first end respectively arranged on the fixing plate and a second end arranged at the tube pin, and the connecting belt connects the base island and the tube pin; The pins are composed of inner pins on the inside and outer pins on the outside, the fixing plate includes a fixing layer, a conductive layer and an insulating layer arranged between the fixing layer and the conductive layer, the fixing plate is fixedly bonded to the base island through the fixing layer, the connecting belt is a conductive metal belt, the chip and the conductive layer of the fixing plate are electrically connected through the metal leads, and are electrically connected to the inner pins through the conductive metal belt.

2. The QFN package structure according to claim 1, characterized in that: The fixing plate is arranged adjacent to the edge of the base island, the connecting belt and the metal lead are arranged in parallel, and the second end of the connecting belt is connected to the inner pin close to the fixing plate.

3. The QFN package structure according to claim 2, characterized in that: The QFN packaging structure includes at least two fixing plates, and at least one fixing plate is disposed on two opposite sides of the base island.

4. The QFN package structure according to claim 1, characterized in that: The fixing layer and the conductive layer are copper layers, and the insulating layer is an insulating resin layer arranged between two copper layers.

5. The QFN package structure according to claim 1, characterized in that: The QFN packaging structure further includes a connection rib connecting different inner pins, and at least one second end of the connection belt is connected to the connection rib.

6. The QFN package structure according to claim 1, characterized in that: The conductive metal strip is an aluminum strip or an aluminum wire.

7. A method for manufacturing a QFN package structure, characterized in that: Includes steps: Providing a packaging frame and placing the chip on a base island of the packaging frame; fixing at least one fixing sheet to the base island; Leading metal leads between the chip and the inner pins of the packaging frame; A connecting strip is provided between the fixing plate and the inner pin of the frame, and the connecting strip is a conductive metal strip; “Fixing at least one fixing sheet on the base island” specifically includes: Bonding two layers of copper sheets by insulating resin glue to form a fixed sheet; The method further comprises the steps of: Metal leads are led between the chip and the fixing sheet.

8. The method for manufacturing a QFN package structure according to claim 7, characterized in that: "Fixing at least one fixing sheet on the base island" also includes: At least two of the fixing plates are fixed at the edge of the base island, and at least one fixing plate is respectively arranged on two opposite sides of the base island.

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