A ceramic small outline packaged lead frame and welding structure

Abstract

This utility model discloses a series of lead frames and a welding structure for a small ceramic outer shell. Multiple lead frames are interconnected by a connecting rib structure. The U-shaped frame effectively buffers the thermal expansion during soldering between the lead frames. Limiting ends on the opposite sides of the lead frames further improve the alignment accuracy during soldering, thus ensuring overall soldering efficiency. Contact terminals at both ends of the series of lead frames facilitate the overall nickel-gold plating process after soldering, solving the problem of collisions caused by bundling individual products in existing technologies. This reduces the probability of scratches on the plating layers and improves plating efficiency and yield.

Description

Technical Field

[0001] This utility model relates to a chip packaging structure, specifically to a connected lead frame structure and its welding structure. Background Technology

[0002] Ceramic Small Outline Package (CSOP) is a common surface-mount package with leads extending from both sides. CSOPs offer advantages such as low manufacturing cost, excellent performance, high reliability, small size, light weight, and high package density, and are widely used in integrated amplifiers, drivers, memories, and comparators.

[0003] The CSOP type product consists of three parts: a ceramic substrate, a metal cover, and an internal adapter ceramic plate. The ceramic substrate further comprises four parts: a sealing area (sealing ring), a chip bonding area, a finger bonding area, and an external lead frame. The main function of the CSOP type product is to provide connectivity for circuits and signals, offering internal and external circuit connections, mechanical support, and hermetic environmental protection. The ceramic substrate is the main body of the casing, primarily serving a mechanical support function; the chip bonding area is the chip mounting platform; and the finger bonding area and external lead frame form the interconnection pathways between the chip and external circuits.

[0004] In conventional CSOP products, a single ceramic base is welded to a single independent lead frame. Due to the difference in thermal expansion coefficients between the lead material and the ceramic base, thermal expansion displacement easily occurs during the welding process, causing misalignment and affecting the weld quality. Furthermore, when electroplating the welded CSOP products, to improve electroplating efficiency, they often need to be bundled together individually or connected using additional clamps to achieve electrical connection between the products. However, bundling can easily cause collisions and scratches between the products, while using additional clamps is less efficient. Summary of the Invention

[0005] Purpose of the invention: In view of the above-mentioned prior art, a ceramic small-shape shell packaged lead frame and welding structure is proposed to improve welding efficiency and accuracy, and facilitate overall electroplating after welding.

[0006] Technical solution: A ceramic small-outer-size shell packaged interconnected lead frame, comprising: an interconnected lead frame obtained by full-plate etching, adjacent lead frames being interconnected by a connecting rib structure, each lead frame having a limiting end on its outer side, and the two ends of the interconnected lead frame respectively having contact terminals for electroplating connection; wherein, the connecting rib structure includes a U-shaped frame, and a set of opposite sides of the U-shaped frame are respectively connected to the opposite lead frame by two symmetrical metal strips.

[0007] Furthermore, in the lead frame, two rows of leads are drawn out from opposite sides of the frame, and the outer side of the midpoint of the opposite sides is connected to the limiting end, and the arrangement direction of each lead frame in the continuous lead frame is perpendicular to the length direction of the lead.

[0008] Furthermore, the aspect ratio of the U-shaped frame is 9 to 12:1, and adjacent lead frames are connected to the long side of the U-shaped frame through the metal strip.

[0009] A ceramic small-outer-shape housing encapsulated lead wire welding structure includes the aforementioned lead wire frame and a welding mold. Several ceramic bases are inverted and installed in the welding mold. The lead wire frame is integrally embedded in the welding mold, with each lead wire frame facing each ceramic base. The lead wire frame is welded to each ceramic base by solder.

[0010] Furthermore, the welding mold is a graphite mold.

[0011] Beneficial effects: In the continuous lead frame and welding structure of this utility model, multiple lead frames are interconnected by a connecting rib structure. The U-shaped frame can effectively buffer the thermal expansion of the brazing between the lead frames. The limiting ends on the opposite sides of the lead frames further improve the alignment accuracy of the welding, thereby ensuring the overall welding efficiency.

[0012] The contact terminals set at both ends of the lead frame facilitate the overall electroplating nickel-gold process after welding, solving the problem of collision caused by bundling individual products in the existing technology, thereby reducing the probability of the plating layers being scratched by each other and improving electroplating efficiency and yield. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the continuous lead frame of this utility model;

[0014] Figure 2 This is a schematic diagram of the welded structure of the connected lead wires of this utility model;

[0015] Figure 3 yes Figure 2 Enlarged schematic diagram of the assembly between the middle connecting lead frame and the welding mold. Detailed Implementation

[0016] The present invention will be further explained below with reference to the accompanying drawings.

[0017] like Figure 1As shown in the figure, a row-connected lead frame encapsulated in a ceramic small outline package is obtained by full-plate etching and includes 6 lead frames 1 of the same model. In each lead frame 1, two rows of leads are led out from opposite sides of the frame, and a rectangular limiting end 3 is respectively connected to the outside of the midpoints of the opposite sides. In this row-connected lead frame, the arrangement direction of each lead frame 1 is perpendicular to the lead length direction.

[0018] In the row-connected lead frame structure, adjacent lead frames 1 are interconnected through a connecting rib structure 2. The connecting rib structure 2 includes a square frame, and a set of opposite sides of the square frame are respectively connected to one side of the opposite lead frame 1 through two symmetric metal strips.

[0019] Specifically, the aspect ratio of the length to the width of the square frame is 9-12:1, and adjacent lead frames 1 are respectively connected to the long sides of the square frame through metal strips.

[0020] In this embodiment, the line width of the square frame is 0.4 mm, the length of the square frame is 15 mm, and the width of the square frame is 1.3 mm; the line width of the metal strip is 0.3 mm, and the length of the metal strip is 2.0 mm.

[0021] At both ends of the row-connected lead frame, contact terminals 4 for electroplating connection are respectively provided. The contact terminals 4 are also connected to the side edges of the corresponding lead frames 1 through two metal strips, and the line width of the metal strip is 0.5 mm.

[0022] As Figure 2 shown in the figure, a row-connected lead welding structure encapsulated in a ceramic small outline package includes the above-mentioned row-connected lead frame, and also includes a graphite welding die 5. Six embedding positions for ceramic bases 6 are provided in the welding die 5, and each ceramic base 6 is倒装 in the welding die 5; the row-connected lead frame is integrally embedded in the welding die 5, and each lead frame 1 faces each ceramic base 6, so that the two rows of lead ends of the lead frame 1 are opposite to the finger-shaped bonding areas of the ceramic bases 6 one by one, and then brazing connection is carried out through solder 7. The solder can be Ag72Cu28.

[0023] As Figure 3 shown in the figure, during the brazing process, the distance between the limiting end 3 on the lead frame 1 and the welding die 5 is the gap 8, and this gap effectively limits the lateral displacement of the row-connected lead frame; the distance between the lead frame 1 and the welding die 5 is the gap 9, which effectively limits the longitudinal displacement of the row-connected lead frame; the above two gaps are controlled within 0.05 mm through the process. The connecting rib structure 2 of the square frame can effectively buffer the thermal expansion between the lead frames 1, thereby improving the welding accuracy.

[0024] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A ceramic QFP package with a continuous array lead frame, characterized by, include: The lead frame obtained by etching the whole plate is interconnected by a connecting rib structure (2) between adjacent lead frames (1). Each lead frame (1) is provided with a limiting end (3) on its outer side. The two ends of the lead frame are respectively provided with contact terminals (4) for electroplating connection. The connecting rib structure (2) includes a U-shaped frame. A set of opposite sides of the U-shaped frame are connected to the lead frame (1) opposite to it by two symmetrical metal strips.

2. The ceramic QFN package array leadframe of claim 1, wherein, In the lead frame (1), two rows of leads are drawn out from the opposite sides of the frame, and the outer side of the midpoint of the opposite sides is connected to the limiting end (3). The arrangement direction of each lead frame (1) in the continuous lead frame is perpendicular to the length direction of the lead.

3. The ceramic QFN package array leadframe of claim 1, wherein, The aspect ratio of the U-shaped frame is 9~12:1, and the adjacent lead frames (1) are connected to the long side of the U-shaped frame through the metal strip.

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