Lead frame

Abstract

A lead frame relates to the technical field of lead frames, and comprises a wafer base and a plurality of pins, each pin is arranged at the side of the wafer base, and the bottom surface of each pin is provided with a pre-cutting groove, so that the pins can be cut off at the pre-cutting grooves when the lead frame is packaged and separated and cut. Pre-cutting grooves are formed in the bottom faces of the pins, in the packaging process of the lead frame, electroplating layers can be formed on the surfaces of the pins in the electroplating procedure, the pins are cut off at the pre-cutting grooves when the pre-cutting grooves are separated and cut after packaging, the cut faces of the pins are small, the electroplating layers are formed on the side walls of the pre-cutting grooves, the stable tin climbing characteristic is prone to occurring during SMT, and the tin soldering reliability is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of lead frames. Background Art

[0002] At present, traditional package types such as QFP, TSOP, SOT, SOP are widely used in the fields of consumer electronics and automotive electronics. These package types with long pins are formed into seagull-shaped pins for mounting on PCB circuit boards after processes such as injection molding, electroplating, rib cutting and molding, and separation cutting. The problem with this type of package is that the cut surface of the pin after separation cutting is the copper surface. Since copper is easily oxidized, the cut surface of the pin's outer foot will oxidize to form an oxide film, which makes it difficult to have stable tin creep characteristics during SMT, and the soldering reliability is low. Utility Model Content

[0003] In view of this, the utility model provides a lead frame, which can easily make the pins have stable solder creeping characteristics during SMT after packaging, and has high soldering reliability.

[0004] The lead frame comprises a wafer base and a plurality of pins, each pin being arranged on the side of the wafer base, and a pre-cut groove being arranged on the bottom surface of the pin so that the pin can be cut off at the pre-cut groove when the lead frame is packaged and separated and cut.

[0005] A pre-cut groove is set on the bottom surface of the pin. During the use of this lead frame packaging process, the electroplating process will form an electroplating layer on the surface of the pin, including the pre-cut groove. When separating and cutting after packaging, the pin is cut at the pre-cut groove. The cut surface of the pin is small, and a plating layer is formed on the side wall of the pre-cut groove. Stable tin creep characteristics are likely to appear during SMT, and the soldering reliability is higher.

[0006] It also includes a frame and fixed columns. The wafer base is connected and fixed to the frame through the fixed columns. The pins are connected and fixed to each other through the fixed columns and to the frame.

[0007] The pre-cut groove is made by a half-etching process or a punching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a bottom view of the lead frame of the present invention.

[0009] Figure 2 For along Figure 1 Cross-sectional view along the AA direction.

[0010] Figure 3 The lead frame of the utility model is separated and cut along the back edge Figure 1 Cross-sectional view along the AA direction.

[0011] Reference numerals include:

[0012] Wafer base 1;

[0013] Pin 2, pre-cut groove 21;

[0014] Frame 3, fixed column 4. DETAILED DESCRIPTION

[0015] The present invention is described in detail below in conjunction with specific embodiments.

[0016] like Figure 1 As shown, the lead frame of this embodiment includes a wafer base 1 and a plurality of pins 2, and usually also includes a frame 3 and a fixed column 4. The function of the fixed column 4 is to connect the wafer base 1 with the frame 3, the pins 2, and the pins 2 with the frame 3, and to fix the relative position between the wafer base 1 and each pin 2 until the relative position between the wafer base 1 and each pin 2 is fixed by plastic sealing after injection molding. Thereafter, the fixed column 4 is cut off in the rib cutting process to insulate the wafer base 1 from the pins 2 and each pin 2.

[0017] Each pin 2 is arranged on the side of the wafer base 1, and is combined with Figure 1 and Figure 2 The bottom surface of the lead 2 is provided with a pre-cut groove 21, so that the lead 2 can be cut at the pre-cut groove 21 when the lead frame is packaged and separated and cut. The dotted line a in the figure is the cutting position. The pre-cut groove 21 is usually made by a half-etching process or a stamping process when the lead frame is produced. Half-etching means that no etching is performed. In the electroplating process of producing the lead frame, the surface of the lead frame is electroplated to form an electroplating layer, and the same is true for each surface of the pre-cut groove 21. After the package is separated and cut, the lead frame is combined with the pre-cut groove 21. Figure 2 and Figure 3 , b is the cut surface, c is the side surface of the pre-cut groove 21, the cut surface b has no electroplating layer, which will oxidize to form an oxide film, and the side surface c of the pre-cut groove 21 has an electroplating layer, which is prone to stable tin creeping characteristics during SMT, making the welding reliability higher.

[0018] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A lead frame, comprising a wafer base and a plurality of pins, each pin being arranged on the side of the wafer base, characterized in that: The bottom surface of the pin is provided with a pre-cut groove, which runs through the pin horizontally, so that the pin can be cut off at the pre-cut groove when the lead frame is packaged and separated and cut.

2. The lead frame according to claim 1, wherein: It also includes a frame and fixed columns. The wafer base is connected and fixed to the frame through the fixed columns. The pins are connected and fixed to each other through the fixed columns and to the frame.

3. The lead frame according to claim 1, wherein: The pre-cut grooves are made by a half-etching process.

4. The lead frame according to claim 1, wherein: The pre-cut grooves are produced by a punching process.

Images