Quad flat no-lead (QFN) packaging lead frame and packaging piece and packaging method thereof

Abstract

The invention provides a QFN (quad flat no-lead) packaging lead frame, which reduces the cost, improves the material utilization rate and is good in packaging reliability. The lead frame comprises a lead frame body, two packaging modules are sequentially arranged on the lead frame body along the long edge of the lead frame body, packaging units in each packaging module are arranged in a corresponding area of the lead frame body in a rectangular array mode, and every two adjacent packaging modules are separated through a spacing bar. The sides of the lead frame body and the spacing bars are provided with stress release holes.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor packaging, specifically to a QFN package lead frame. The invention also provides a package for the lead frame and a packaging method. Background Technology

[0002] QFN (Quad Flat No-leads Package) is an advanced microelectronic assembly and packaging device that is currently in a mature development stage. QFN packaging technology offers advantages such as low failure rate, high density, miniaturization, rapid heat dissipation, space saving, and lower cost, which can shorten product launch time and reduce investment risk. Although QFN packaging technology is relatively mature and various packaging companies have already mass-produced it, the lead frames used in this packaging technology are basically single-unit packaging, with 25 or 16 rows. From a packaging cost perspective, the low number of lead rows results in low material utilization and high cost. Therefore, there is an urgent need to develop a QFN package lead frame that can reduce costs and improve material utilization. Summary of the Invention

[0003] To address the above problems, this invention provides a QFN package lead frame that reduces costs, improves material utilization, and offers good package reliability.

[0004] A QFN package lead frame is characterized in that: it includes a lead frame body, on which two packaging modules are sequentially arranged along its long side, and the packaging units in each packaging module are arranged in a rectangular array in the corresponding area of ​​the lead frame body. Adjacent packaging modules are separated by spacers, and stress relief holes are provided on the sides of the lead frame body and on the spacers.

[0005] Its further features are: The lead frame body has a process electroplating ring and vent holes on its overall outer shape, which helps to improve the consistency of electroplating and the pass rate of plastic-encapsulated products. The improved consistency of the frame plating layer significantly improves the reliability of the second bonding of the wire. The frame packaging unit carrier edge of each packaging unit adopts a sawtooth structure, the front of the carrier area corresponding to each packaging unit is a semi-etched structure, and pin locking holes are provided on the outer four sides of each packaging unit. Due to the above structure, the contact area between the molding body and the frame is increased for products of the same area, enhancing the adhesion and improving the reliability of the product. The edges of the frame packaging unit carrier are electroplated at intervals to reduce the silver plating area, increase the contact area between the molding compound and the bare copper, and improve the reliability of the product. The central rib connecting rods used for cutting between adjacent packaging units adopt a T-shaped structure. The central rib connecting rods correspond to the cutting position and include a thick center end and thin ends on both sides. This improves the overall strength of the frame, reduces the thickness of the central rib connecting rods, i.e. the thickness of the metal in the cutting path, and solves the problems of metal residue and abnormal deformation and tearing during the cutting process. This improves product reliability and indirectly reduces the amount of cutting blades used.

[0006] A package that is obtained by encapsulation with a QFN package lead frame.

[0007] The present invention also discloses a packaging method for a package, characterized by comprising the following steps: S1 is used for wafer thinning and dicing; S2 takes the lead frame; S3 chip mounting involves attaching the chip to the center area of ​​the corresponding packaging unit on the lead frame, followed by rapid curing and baking. S4 plasma cleaning; S5 pressure welding; S6 plasma cleaning; S7 plastic sealing; S8 electroplating; S9 cutting; The S10 test prints tape and reel to produce the required QFN package.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention discloses a high-reliability QFN package lead frame and its encapsulation components. The lead frame includes a lead frame body with two encapsulation modules disposed on the lead frame body. Each encapsulation module contains encapsulation units arranged in a matrix. This design transforms the original single encapsulation module lead frame arrangement into two encapsulation modules, increases the number of encapsulation components in a single encapsulation unit, improves copper utilization, and enhances production efficiency. It reduces costs, improves material utilization, and provides high encapsulation reliability. Attached Figure Description

[0009] Figure 1 This is a top view structural diagram of the present invention; Figure 2 for Figure 1 A partially enlarged structural diagram; Figure 3 This is a front view of the packaging unit of the present invention; Figure 4 This is a rear view of the packaging unit of the present invention; Figure 5 This is a front view of a combination of several groups of packaging units on the side of the present invention; Figure 6 for Figure 5 A magnified view of section B; Figure 7 for Figure 6 A magnified schematic diagram of the AA section; The names corresponding to the serial numbers in the diagram are as follows: Lead frame body 10, encapsulation module 101, encapsulation unit 1011, spacer 102; 1. Stress relief hole; 2. Process electroplating ring; 3. Vent hole; 4. Frame packaging unit carrier edge; 5. Carrier area; 6. Pin locking hole; 7. Central rib connecting rod; 71. Center thick end; 72. Thin end; 8. Interval electroplating structure. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is intended merely to illustrate selected embodiments of this application and is not intended to limit the scope of protection claimed by this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0011] It should be understood that in the description of embodiments of the present invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of the stated features.

[0012] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0013] A QFN packaged lead frame, see Figures 1-7It includes a lead frame body 10, on which two encapsulation modules 101 are sequentially arranged along its long side. The encapsulation units 1011 in each encapsulation module 101 are arranged in a rectangular array in the corresponding area of ​​the lead frame body. Adjacent encapsulation modules 101 are separated by spacers 102. Stress relief holes 1 are provided on the sides of the lead frame body 10 and on the spacers.

[0014] In a specific embodiment, the lead frame body 10 has a length L of 270±0.05mm, a width W of 83.0±0.05mm, and a thickness H of 0.152±0.008mm. The lead frame body 10 is provided with two packaging modules 101. The packaging units 1011 in each packaging module 101 are arranged in a matrix of 30 rows and 17 columns, for a total of 510 packaging units 1011.

[0015] like Figure 1 As shown, the length and width of the plastic encapsulation body in the encapsulation module 101 of the lead frame of the present invention have been increased from the original 125mm and 70mm to 130.5mm and 74.6mm, respectively. By increasing the volume of the plastic encapsulation body, the number of encapsulation components in a single encapsulation unit increases, the copper material utilization rate is improved, and the production efficiency is increased.

[0016] In a specific embodiment, the overall outer shape of the lead frame body 10 is provided with a process electroplating ring 2 and an exhaust hole 3, which helps to improve the consistency of electroplating and the pass rate of the plastic-encapsulated products. The improvement of the consistency of the frame plating layer significantly improves the reliability of the second welding of the wire bonding. The frame packaging unit carrier edge 4 corresponding to each packaging unit 1011 adopts a sawtooth structure, the front of the carrier area 5 corresponding to each packaging unit 1011 is a semi-etched structure, and the outer four sides of each packaging unit 1011 are provided with pin locking holes 6. Due to the above structure, the contact area between the molding body and the frame is increased for products of the same area, enhancing the adhesion and improving the reliability of the product. The frame packaging unit carrier edge 4 adopts an intermittent electroplating structure 8, which reduces the silver plating area, increases the contact area between the molding compound and the bare copper, and improves the reliability of the product. The central rib connecting rod 7 for cutting between adjacent packaging units 1011 adopts a T-shaped structure. The central rib connecting rod 7 includes a thick center end 71 and two thin ends 72 on both sides corresponding to the cutting position. This improves the overall strength of the frame, reduces the thickness of the central rib connecting rod, i.e. the thickness of the metal in the cutting path, solves the problems of metal residue and abnormal deformation and tearing during the cutting process, improves product reliability, and indirectly reduces the amount of cutting blades used.

[0017] A package that is obtained by encapsulation with a QFN package lead frame.

[0018] The present invention also discloses a packaging method for a package, which includes the following steps: S1 performs wafer thinning and dicing, using the existing SSOP packaging manufacturing process; S2 takes a lead frame, which includes a lead frame body, and the lead frame body is divided into two packaging modules arranged in a matrix with 510 packaging units. For S3 chip mounting, an environmentally friendly acrylic fast-curing adhesive with a viscosity ≥12000CP and water absorption ≤0.2% is used to attach the chip to the center area of ​​the corresponding packaging unit of the lead frame. After chip mounting, rapid curing and baking are performed. S4 plasma cleaning; S5 pressure bonding uses QFN packaging manufacturing process for pressure bonding; S6 plasma cleaning; The S7 is encapsulated using environmentally friendly materials that meet EU WEEE, RoHS and Sony standards. The encapsulation process utilizes multi-stage injection molding with vacuum adsorption and anti-delamination curing technology. S8 electroplating; S9 cutting; The S10 test printing tape is used to produce the required QFN package. The existing SSOP packaging production process is used for printing, testing, and tape production to obtain the QFN package.

[0019] The leadframe itself has two packaging modules. The packaging units of each module are arranged in a matrix of 30 rows and 17 columns on the leadframe body. The leadframe body is 270±0.10mm long, 83.0±0.05mm wide, and 0.152±0.08mm thick. The leadframe frame structure is equipped with electroplating rings, unit spacing, venting holes, and stress relief holes, which help improve the uniformity of the electroplating layer, improve the reliability of wire bonding, facilitate the discharge of molding gas, and release stress after molding. The full release of stress after molding minimizes the risk of cracks and delamination in the unit molding. In addition, the carrier edge is designed with a serrated structure, the middle part of the carrier is semi-etched on the front, the pads are equipped with locking holes, and the carrier silver plating adopts a segmented electroplating process to reduce the silver plating area to achieve a stronger locking effect. When manufacturing the package, the frame material and molding compound are used to the maximum extent, improving material utilization, while improving production efficiency and product quality, reducing process defect rate, and improving product yield.

Claims

1. A QFN packaged lead frame, characterized in that: It includes a lead frame body, on which two encapsulation modules are sequentially arranged along its long side. The encapsulation units in each encapsulation module are arranged in a rectangular array in the corresponding area of ​​the lead frame body. Adjacent encapsulation modules are separated by spacers. Stress relief holes are provided on the sides of the lead frame body and on the spacers.

2. The QFN package lead frame according to claim 1, characterized in that: The lead frame body has a process electroplating ring and an exhaust hole on its overall outer edge.

3. A QFN package lead frame according to claim 2, characterized in that: The frame packaging unit carrier edge of each packaging unit adopts a sawtooth structure, the front of the carrier area corresponding to each packaging unit is a semi-etched structure, and pin locking holes are provided on the outer four sides of each packaging unit.

4. A QFN package lead frame according to claim 3, characterized in that: The edges of the frame packaging unit carrier are plated with intermittent electroplating to reduce the silver plating area and increase the contact area between the molding compound and the bare copper.

5. A QFN package lead frame according to claim 1, characterized in that: The central rib connecting rods for cutting between adjacent packaging units adopt a T-shaped structure, and the central rib connecting rods include a thick center end and two thin ends corresponding to the cutting position.

6. A package, characterized in that: It is obtained by packaging with a QFN packaged lead frame as described in any one of claims 1-5.

7. A method for packaging a package, characterized in that, It includes the following steps: S1 is used for wafer thinning and dicing; S2 takes a lead frame, which adopts a QFN packaged lead frame as described in any one of claims 1-5; S3 chip mounting involves attaching the chip to the center area of ​​the corresponding packaging unit on the lead frame, followed by rapid curing and baking. S4 plasma cleaning; S5 pressure welding; S6 plasma cleaning; S7 plastic sealing; S8 electroplating; S9 cutting; The S10 test prints tape and reel to produce the required QFN package.

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