A DFN or QFN lead frame and its manufacturing method

Abstract

This invention relates to a DFN or QFN lead frame and its manufacturing method. The lead frame includes a base island, leads, and a molding compound, which connects the base island and leads into a single frame. It employs a completely new structure, departing entirely from the copper sheet stamping process. The molding compound connects the base island and leads into a single frame, ensuring the position and secure fixation of the base island and leads. Since it eliminates the need for connecting ribs and perimeter borders found in traditional lead frames, the copper material utilization rate is very high, and pre- or post-film bonding processes are unnecessary. The lead frame has higher strength and is less prone to deformation due to production abnormalities. The leads also have greater strength and support, preventing base island or lead deformation caused by multiple bonding processes. After being packaged into a single-chip product, the chip is completely encapsulated by the molding compound due to the absence of connecting ribs, providing excellent sealing and making it extremely difficult for moisture to penetrate the molding compound. This eliminates the possibility of excess adhesive during the molding process.

Description

Technical Field

[0001] This invention relates to the field of chip packaging technology, and in particular to a DFN or QFN lead frame and its manufacturing method. Background Technology

[0002] DFN or QFN is a flat, leadless chip package. DFN (Dual Flat No-lead Package) is a dual-sided flat no-lead package, and QFN (Quad Flat No-lead Package) is a quad-sided flat no-lead package. Both packages require lead frames. In current technology, lead frames are stamped from copper sheets and consist of multiple lead frame units connected by ribs to form an array. The chip is then bonded to the lead frame, wires are attached, and the package is then encapsulated and cut to obtain a single packaged product. This type of lead frame has low material utilization, generally low lead strength, and is prone to deformation during multiple wire bonding processes, requiring improvement. Summary of the Invention

[0003] The purpose of this invention is to provide a DFN or QFN lead frame with high material utilization and high strength, and a method for manufacturing the same.

[0004] The technical solution provided by this invention is: a DFN or QFN lead frame, comprising a base island, pins and molding compound, wherein the molding compound connects the base island and pins into an integral frame.

[0005] Some of these pins are shared by adjacent lead frame units.

[0006] Another technical solution provided by the present invention is: a method for manufacturing the above-described DFN or QFN lead frame, comprising the following steps:

[0007] S1: Arrange the elongated base islands and pins in the injection mold according to the required positions;

[0008] S2: Inject molding compound into the injection mold. The molding compound wraps around the base island and the lead to form a columnar body.

[0009] S3: Cut the columnar body into thin slices to form a DFN or QFN lead frame.

[0010] Before step S1, there is also step S0.5, in which molten copper is poured into a casting mold to form elongated base islands and pins.

[0011] The beneficial effects of this invention are as follows: The DFN or QFN lead frame adopts a completely new structure, departing entirely from the copper sheet stamping process. The base island and pins are connected into a single frame using molding compound (equivalent to embedding the base island and pins onto the molding compound). The molding compound ensures the position and secure fixation of the base island and pins. Since there is no need for connecting ribs and surrounding borders as in traditional lead frames, the copper material utilization rate is very high, eliminating the need for pre- or post-film bonding processes. The lead frame has higher strength and is less prone to deformation due to production abnormalities. The pins also have greater strength and support, preventing base island or pin deformation caused by multiple bonding processes. After being packaged into a single-chip product, the chip is completely encapsulated by the molding compound due to the absence of connecting ribs, providing excellent sealing and making it extremely difficult for moisture to penetrate the molding compound. It eliminates the phenomenon of excess adhesive during the molding process. It has significant advantages in both cost and performance and is worthy of promotion. Attached Figure Description

[0012] Figure 1 This is a three-dimensional schematic diagram of a first embodiment of the DFN or QFN lead frame described in this invention;

[0013] Figure 2 This is a three-dimensional schematic diagram of the lead frame unit in Embodiment 1 of the DFN or QFN lead frame of the present invention;

[0014] Figure 3 This is a schematic diagram of the arrangement of the elongated base island and pins in step one of the manufacturing method of the DFN or QFN lead frame described in this invention.

[0015] Figure 4 This is a schematic diagram of the columnar body formed after injection molding of the encapsulating material in step two of the manufacturing method of the DFN or QFN lead frame of the present invention.

[0016] Figure 5 This is a schematic diagram of step three of the manufacturing method of the DFN or QFN lead frame of the present invention, after the columnar body is cut into thin slices.

[0017] Figure 6 This is a top view of a first embodiment of the DFN or QFN lead frame described in this invention;

[0018] Figure 7 This is a top view of Embodiment 2 of the DFN or QFN lead frame described in this invention;

[0019] Figure 8 This is a top view of Embodiment 3 of the DFN or QFN lead frame described in this invention;

[0020] Figure 9 This is a top view of Embodiment 4 of the DFN or QFN lead frame described in this invention.

[0021] Figure 1, 6 The dashed lines in 7, 8, and 9 are only used to distinguish the lead frame units and are not structural lines.

[0022] The components are: 1. Base island; 2. Pin; 3. Molding compound; 4. Lead frame unit. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] As one embodiment of the DFN or QFN lead frame described in this invention, such as Figures 1 to 6 As shown, it includes a base island 1, pins 2 and molding compound 3, wherein the molding compound 3 connects the base island 1 and pins 2 into an integral frame.

[0025] The manufacturing method of the DFN or QFN lead frame of the present invention includes the following steps:

[0026] S1: Arrange the elongated base islands and pins in the injection mold according to the required positions;

[0027] S2: Inject molding compound into the injection mold. The molding compound wraps around the base island and the lead to form a columnar body.

[0028] S3: Cut the columnar body into thin slices to form a DFN or QFN lead frame.

[0029] The DFN or QFN lead frame adopts a completely new structure, departing entirely from the copper sheet stamping process. The base island 1 and pin 2 are connected into a single frame using molding compound 3 (equivalent to embedding the base island 1 and pin 2 onto the molding compound 3). The molding compound 3 ensures the position and secure fixation of the base island 1 and pin 2. Since there is no need for the connecting ribs and surrounding borders found in traditional lead frames, the copper material utilization rate is very high, eliminating the need for pre- or post-film bonding processes. The lead frame has higher strength and is less prone to deformation due to production abnormalities. The pin 2 also has greater strength and support, preventing base island or pin deformation caused by multiple bonding processes. After being packaged into a single-chip product, the chip is completely encapsulated by the molding compound due to the absence of connecting ribs, providing excellent sealing and making it extremely difficult for moisture to penetrate the molding compound. This eliminates the problem of excess adhesive during the molding process. It offers significant advantages in both cost and performance and is worthy of widespread adoption.

[0030] In this embodiment, some pins are shared by adjacent leadframe units. During the dicing process, the molded leadframe needs to be separated into individual packaged products, requiring the shared pins to be cut in half. To avoid cutting the metal, a method such as... Figure 8 The technical solution shown (Embodiment 3) only requires cutting the molding compound when cutting into chip units, making the cutting process easier.

[0031] Before step S1 of this invention, step S0.5 is included, in which molten copper is poured into a casting mold to form elongated base islands and leads. Of course, elongated base islands and leads can also be manufactured in other ways.

[0032] As a second embodiment of the DFN or QFN lead frame described in this invention, such as Figure 7 As shown, the difference from Embodiment 1 is that the lead frame unit 4 has pins 2 on all four sides (in Embodiment 1, only two sides have pins), while the other structures and beneficial effects are the same as in Embodiment 1.

[0033] As a fourth embodiment of the DFN or QFN lead frame described in this invention, such as Figure 9 As shown, the difference from Embodiment 2 is that there are no shared pins. When cutting into chip units, only the molding compound is cut, making the cutting easier.

[0034] In this application, embodiments one to four are all 3*4 arrays with a total of 12 lead frame units 4. This is only an example. In actual production, it can be an m*n array or an m*m array, where m and n are natural numbers.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a DFN or QFN lead frame, characterized in that, It includes a base island, pins, and molding compound, wherein the molding compound connects the base island and pins into a single frame, without connecting ribs in the lead frame or a surrounding border; Includes the following steps: S1: Arrange the elongated base islands and pins in the injection mold according to the required positions; S2: Inject molding compound into the injection mold. The molding compound wraps around the base island and the lead to form a columnar body. S3: Cut the columnar body into thin slices to form a DFN or QFN lead frame.

2. The method for manufacturing the DFN or QFN lead frame according to claim 1, characterized in that, Some of these pins are shared by adjacent lead frame units.

3. The manufacturing method of the DFN or QFN lead frame according to claim 1, characterized in that, Before step S1, there is also step S0.5, in which molten copper is poured into a casting mold to form elongated base islands and pins.

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