A pin structure of QFN package

Abstract

The invention discloses a pin structure of a QFN package, comprising a frame substrate and a plastic packaging material, wherein a base island fixing area and an etching area are provided on the frame substrate, wherein the etching area is located at the periphery of the base island fixing area; the base island fixing area comprises a chip and a base island for fixing the chip, wherein the chip is connected to the top surface of the base island; a semi-etched base island bracket is provided between the etching area and the base island, wherein the etching area comprises a plurality of pins, wherein the edge of each pin is provided with a semi-etched edge area, wherein a semi-etched groove is provided in the edge area; the chip is connected to the pins through welding wires, wherein the etching area, the base island fixing area and the welding wires are all plastic-sealed in the plastic packaging material, and the edge area and the groove in the edge area are filled with the plastic packaging material; the step groove formed by the edge area and the groove in the edge area of ​​the present application can increase the attachment area and the attachment strength of the plastic packaging material and the pins, thereby improving the reliability of the QFN package and the stability of the chip.

Description

Technical Field

[0001] The present invention relates to the technical field of chip packaging, and particularly to a pin structure for QFN packaging. Background Art

[0002] With the rapid growth of QFN applications, high-performance QFN products will surely gain good returns in the domestic and international IC packaging and testing markets. The adhesion strength between the QFN lead frame plastic package and the lead frame determines the reliability of QFN packaging, thus affecting the stability of the chip. In the QFN lead frame of the prior art, peeling between the lead frame and the plastic encapsulant easily occurs during plastic encapsulation, reducing the reliability of QFN packaging and the stability of the chip. Summary of the Invention

[0003] The purpose of the present invention is to provide a pin structure for QFN packaging to solve the problem of poor stability and reliability between the plastic encapsulant and the lead frame in the prior art.

[0004] To achieve the above purpose, the present invention is implemented by adopting the following technical solution:

[0005] A pin structure for QFN packaging includes a frame substrate and a plastic encapsulant. The frame substrate is provided with a base island fixing area and an etching area, and the etching area is located on the outer periphery of the base island fixing area;

[0006] The base island fixing area includes a chip and a base island for fixing the chip, and the chip is connected to the top surface of the base island;

[0007] A semi-etched base island support is provided between the etching area and the base island. The etching area includes a plurality of pins, and a semi-etched edge area is provided at the edge of each pin, and a semi-etched groove is provided in the edge area;

[0008] The chip is connected to the pins through bonding wires. The etching area, the base island fixing area, and the bonding wires are all encapsulated in the plastic encapsulant, and the edge area and the groove in the edge area are filled with the plastic encapsulant.

[0009] Further, a semi-etched groove is provided in the base island support, and the base island support and the groove in the base island support are filled with the plastic encapsulant.

[0010] Further, the shape of the groove in the base island support is adapted to the shape of the base island support and is in a shape of a rectangle with a hole in the middle.

[0011] Further, the edge area of the pin is located on both sides of the bottom surface of the pin; the groove in the edge area is rectangular.

[0012] Furthermore, the depth of the edge region is 1 / 2-2 / 3 of the thickness of the pin; the depth of the groove in the edge region is 1 / 4 of the thickness of the pin.

[0013] Furthermore, the depth of the base island support is 1 / 2-2 / 3 of the thickness of the frame substrate, and the depth of the groove in the base island support is 1 / 4 of the thickness of the frame substrate.

[0014] Furthermore, the width of the groove in the edge region is 1 / 3 to 2 / 3 of the width of the edge region;

[0015] The width of the groove in the base island bracket is 1 / 3 to 2 / 3 of the width of the base island bracket.

[0016] Furthermore, the molding compound is formed by piling up powdery particles.

[0017] Furthermore, the frame substrate is made of copper.

[0018] Furthermore, there are four etching areas, and the four etching areas are evenly distributed around the base island.

[0019] According to the above technical solution, the embodiments of the present invention have at least the following effects:

[0020] 1. The present application designs a half-etched edge area at the edge of each pin, and designs a half-etched groove in the edge area. The step groove formed by the edge area and the groove in the edge area can increase the attachment area and attachment strength of the plastic encapsulation material and the pin, thereby improving the reliability of the QFN package and the stability of the chip;

[0021] 2. The present application sets a semi-etched base island bracket between the base island and the etching area, and sets a semi-etched groove on the base island bracket. The step groove formed by the base island bracket and the groove in the base island bracket increases the attachment area and attachment strength of the plastic packaging material and the pin, and cooperates with the step groove formed in the edge area to jointly improve the reliability of the QFN package and the stability of the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A top view of the overall structure of a specific embodiment of the present invention;

[0023] Figure 2 for Figure 1 A partial front sectional view of .

[0024] Among them: 1. frame base; 2. base island; 3. base island bracket; 4. pins; 5. chip; 6. edge area; 7. etching area; 8. groove; 9. welding wire; 10. plastic packaging material. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0026] It should be noted that in the description of the present invention, the directions or positional relationships indicated by the terms "front", "rear", "left", "right", "up", "down", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. The terms "front", "rear", "left", "right", "up", and "down" used in the description of the present invention refer to the directions in the accompanying drawings, and the terms "inside" and "outside" refer to the directions toward or away from the geometric center of a specific component, respectively.

[0027] like Figure 1 and Figure 2 As shown, a pin structure of a QFN package includes a frame substrate 1 and a plastic packaging material 10, wherein a base island fixing area and an etching area 7 are provided on the frame substrate 1, and the etching area 7 is located at the periphery of the base island fixing area; the base island fixing area includes a chip 5 and a base island 2 for fixing the chip 5, and the chip 5 is connected to the top surface of the base island 2; a semi-etched base island bracket 3 is provided between the etching area 7 and the base island 2, and the etching area 7 includes a plurality of pins 4, and a semi-etched edge area 6 is provided at the edge of each pin 4, and a semi-etched groove 8 is provided in the edge area 6; the chip 5 is connected to the pin 4 through a welding wire 9, and the etching area 7, the base island fixing area and the welding wire 9 are all plastic-sealed in the plastic packaging material 10, and the edge area 6 and the groove 8 in the edge area 6 are filled with the plastic packaging material 10.

[0028] The present application designs a half-etched edge area at the edge of each pin, and designs a half-etched groove in the edge area. The step groove formed by the edge area and the groove in the edge area can increase the adhesion area and adhesion strength of the plastic packaging material and the pin, thereby improving the reliability of the QFN package and the stability of the chip.

[0029] like Figure 1 As shown, the frame substrate 1 of the present application is made of copper material. A base island fixing area is set on the frame substrate 1, and the base island fixing area includes a base island 2. The base island 2 is used to fix the chip 5. When QFN packaging is performed, the chip 5 is placed on the top surface of the base island 2. The base island 2 is located in the center of the frame substrate 1, and the etching area 7 is located around the base island 2. If the shape of the frame substrate 1 is square, the base island 2 and the chip 5 are located in the center, and the etching area 7 is located on the four sides. The etching areas 7 on the four sides do not contact each other, and the etching area 7 and the base island 2 do not contact each other. A base island bracket 3 for etching by a half-etching process is set between the two, and the base island bracket 3 separates the etching area 7 from the etching area, and separates the etching area from the base island 2.

[0030] A plurality of pins 4 in the same row are arranged in each etching area 7, and the edge area of ​​the pin 4 is etched by a half-etching process, that is, a groove-shaped edge area 6 is formed at the edge of the pin. In some further embodiments, the edge area exists on both sides of the pin, and this design facilitates the etching of the edge area 6.

[0031] In the present application, a half-etched groove 8 is provided in the half-etched edge region 6, and the half-etched groove 8 and the half-etched edge region 6 form a stepped groove. When performing QFN packaging, the formed stepped groove increases the adhesion area and adhesion strength between the plastic packaging material, thereby improving the reliability of the QFN packaging and the stability of the chip.

[0032] In the present application, a half-etched groove is also provided in the half-etched base island support 3, and the half-etched groove 8 and the half-etched base island support 3 form a stepped groove. When performing QFN packaging, the formed stepped groove increases the adhesion area and adhesion strength between the plastic packaging material, thereby improving the reliability of the QFN packaging and the stability of the chip.

[0033] In some embodiments, the edge regions 6 on both sides of the pin 4 are rectangular, and the grooves 8 formed therein are also rectangular.

[0034] In some embodiments, the shape of the half-etched island support 3 is similar to a Chinese umbilical cord, and the shape of the groove formed therein is also a Chinese umbilical cord.

[0035] In some embodiments, the original half-etching depth of the frame is between 1 / 2 and 2 / 3 of the total thickness of the frame, and the increased half-etching depth of the groove is between 1 / 4 of the total thickness of the frame, so as to facilitate further half-etching in the half-etching area to ensure the forming effect of the step groove.

[0036] In some embodiments, the increased groove width is between 1 / 3 and 2 / 3 of the original etching width of the frame, so as to facilitate further half etching in the half-etched area and ensure the forming effect of the step groove.

[0037] like Figure 2 As shown: it also includes a plastic encapsulation material 10, and the plastic encapsulation material 10 encapsulates the etching area 7, the base island 2, the chip 5, and the bonding wire 9 in the plastic encapsulation material 10 by means of plastic encapsulation curing. The plastic encapsulation material 10 is a rectangular parallelepiped (usually formed as a small cylinder, which becomes a liquid to wrap the chip and the frame during plastic encapsulation, and finally solidifies into a shape), and is formed by stacking plastic encapsulation material powder particles. Through the step grooves etched on the periphery of the base island and the edge of the lead pins, the plastic encapsulation material is filled in the step grooves during packaging, which effectively increases the adhesion strength between the plastic encapsulation material and the lead frame, and improves the reliability of the QFN package and the stability of the chip.

[0038] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A pin structure of a QFN package, characterized in that: It includes a frame substrate (1) and a plastic encapsulant (10). A base island fixing area and an etching area (7) are provided on the frame substrate (1), and the etching area (7) is located on the outer periphery of the base island fixing area; The base island fixing area includes a chip (5) and a base island (2) for fixing the chip (5), and the chip (5) is connected to the top surface of the base island (2); A semi-etched base island support (3) is provided between the etching area (7) and the base island (2). The etching area (7) includes a plurality of pins (4), and a semi-etched edge area (6) is provided at the edge of each pin (4), and a semi-etched groove (8) is provided in the edge area (6); The chip (5) is connected to the pins (4) through bonding wires (9). The etching area (7), the base island fixing area, and the bonding wires (9) are all encapsulated in the plastic encapsulant (10), and the plastic encapsulant (10) is filled in the edge area (6) and the groove (8) in the edge area (6); The base island support (3) is provided with a semi-etched groove (8) inside, and the plastic encapsulant (10) is filled in the base island support (3) and the groove (8) inside the base island support (3); The shape of the groove (8) inside the base island support (3) is adapted to the shape of the base island support (3) and is in a shape like a Chinese character 'hui'; The edge area (6) of the pin (4) is located on both sides of the bottom surface of the pin (4); the groove (8) in the edge area (6) is rectangular; The depth of the edge area (6) is 1 / 2 - 2 / 3 of the thickness of the pin (4); the depth of the groove (8) in the edge area (6) is 1 / 4 of the thickness of the pin (4); The depth of the base island support (3) is 1 / 2 - 2 / 3 of the thickness of the frame substrate (1), and the depth of the groove (8) inside the base island support (3) is 1 / 4 of the thickness of the frame substrate (1); The width of the groove (8) in the edge area (6) is 1 / 3 - 2 / 3 of the width of the edge area; The width of the groove (8) inside the base island support (3) is 1 / 3 - 2 / 3 of the width of the base island support (3).

2. The pin structure of the QFN package according to claim 1, characterized in that: The plastic encapsulant (10) is made by piling up powdery particles to form the plastic encapsulant (10).

3. The pin structure of the QFN package according to claim 1, characterized in that: The material of the frame substrate (1) is copper.

4. The pin structure of the QFN package according to claim 1, characterized in that: There are four etching areas (7), and the four etching areas (7) are evenly distributed around the base island (2).

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