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CN-224234190-U - Lead frame structure

CN224234190UCN 224234190 UCN224234190 UCN 224234190UCN-224234190-U

Abstract

The utility model discloses a lead frame structure, wherein a plurality of lead frame bodies are arranged continuously along the axial direction to form the lead frame structure, each lead frame body comprises a lead frame unit, a first sideband and a second sideband, the lead frame units are arranged in four rows up and down and two columns left and right, the first sideband is arranged at the upper end and the lower end of each lead frame body, the second sideband is connected between the left lead frame unit and the right lead frame unit, the lead frame units comprise a base island for bearing chips, a first pin, a second pin, a third pin, a fourth pin and a fifth pin, silver plating layers are arranged at the root parts of the first pin, the second pin, the fourth pin and the fifth pin, and the root part of the third pin is connected with the base island. The problem of current TO-252 lead frame structural design is improper, leads TO stress concentration, and reliability is reduced is solved.

Inventors

  • XIAO CHUANXING
  • XU HONGBO

Assignees

  • 宁波港波电子有限公司

Dates

Publication Date
20260512
Application Date
20250228

Claims (11)

  1. 1. The lead frame structure (100) is characterized in that a plurality of lead frame bodies (10) are arranged continuously along the axial direction to form the lead frame structure (100), each lead frame body (10) comprises a lead frame unit (20), a first side band (30) and a second side band (40), the lead frame units (20) are arranged in four rows up and down and two columns left and right, the first side band (30) is arranged at the upper end and the lower end of each lead frame body (10), the second side band (40) is connected between the left lead frame unit and the right lead frame unit (20), the lead frame units (20) comprise a base island (26) for bearing a chip, a first pin (21), a second pin (22), a third pin (23), a fourth pin (24) and a fifth pin (25), silver plating layers (50) are arranged at the root parts of the first pin (21), the second pin (22), the fourth pin (24) and the fifth pin (25), and the root parts of the third pin (23) are connected with the base island (26).
  2. 2. The leadframe structure (100) according to claim 1, wherein the plated thickness of the silver layer (50) provided at the root of the first (21), second (22), fourth (24), fifth (25) pins is 2.5 μm.
  3. 3. The leadframe structure (100) according to claim 1, wherein the outer sides of the first pin (21) and the fifth pin (25) are provided with semicircular lead holes (27).
  4. 4. The leadframe structure (100) of claim 1, wherein a side of the base island (26) adjacent to the chip is a burr side.
  5. 5. The leadframe structure (100) according to any one of claims 1-4, wherein each leadframe unit (20) is provided with a plurality of first positioning holes (31) on the first side strip (30), wherein one of the first side strips (30) is further provided with a second positioning hole (32), and wherein the second positioning hole (32) is a oblong hole.
  6. 6. The leadframe structure (100) according to claim 5, wherein each leadframe unit (20) is provided with a plurality of third positioning holes (41) and fourth positioning holes (42) on the second side band (40), wherein the fourth positioning holes (42) are oblong holes.
  7. 7. The leadframe structure (100) according to claim 6, characterized in that a first connecting rib (60) is further provided between two adjacent leadframe bodies (10).
  8. 8. The lead frame structure (100) according to claim 5, wherein the lead frame body (10) further comprises a second connecting rib (70) and a reinforcing rib (80), the second connecting rib (70) is connected between two adjacent islands (26), and the reinforcing rib (80) is connected between the pins of two lead frame units (20) which are adjacent to each other.
  9. 9. The leadframe structure (100) of claim 8, wherein the leadframe body (10) further includes a stress relief dovetail (91) open between the second connection rib (70) and the base island (26).
  10. 10. The lead frame structure (100) of claim 8, wherein the lead frame body (10) further comprises a first V-shaped groove (92) formed at edges of the left and right sides of the base island (26), and wherein the first V-shaped groove (92) is located on a side of the base island (26) away from the chip.
  11. 11. The leadframe structure (100) according to claim 8, wherein the pins are provided with stamped circular arcs.

Description

Lead frame structure Technical Field The utility model belongs to the technical field of lead frames, and particularly relates to a lead frame structure. Background The semiconductor lead frame LEAD FRAME is a thin plate metal frame for connecting the contact points of the internal chip of the semiconductor integrated block and the external wires, is a structural material of the semiconductor package, and accounts for 15% of the semiconductor package material market. As a chip carrier for integrated circuits, a lead frame is a critical structural member for electrically connecting the terminals (bond sites) of the internal circuits of the chip to the external leads by means of bonding materials (gold wires, aluminum wires, copper wires) to form an electrical circuit, which acts as a bridge to the external leads. Lead frame plating is an important semiconductor packaging technique that is used primarily to improve the conductivity and heat dissipation of integrated circuit chips. The TO-252 package has a relatively small form factor that facilitates installation and layout in a compact space. However, the existing TO-252 lead frame is prone TO problems of improper structural design, stress concentration and reduced reliability. Disclosure of utility model Aiming at the problem of stress concentration and reliability reduction caused by improper design of the traditional TO-252 lead frame structure, the utility model aims TO provide a lead frame structure, a plurality of lead frame bodies are arranged continuously along the axial direction TO form the lead frame structure, each lead frame body comprises a lead frame unit, a first sideband and a second sideband, the lead frame units are arranged in four rows up and down and two columns left and right, the first sideband is arranged at the upper end and the lower end of each lead frame body, the second sideband is connected between the left lead frame unit and the right lead frame unit, the lead frame unit comprises a base island for bearing a chip, a first pin, a second pin, a third pin, a fourth pin and a fifth pin, silver plating layers are arranged at the root parts of the first pin, the second pin, the fourth pin and the fifth pin, and the root part of the third pin is connected with the base island. Further, the plating thickness of the silver plating layer arranged at the root parts of the first pin, the second pin, the fourth pin and the fifth pin is 2.5 μm. Further, semicircular lead holes are formed in the outer sides of the first pin and the fifth pin. Furthermore, one surface of the base island close to the chip is a burr surface. Further, each lead frame unit is provided with a plurality of first positioning holes on the first side belt, one of the first side belt is also provided with a second positioning hole, and the second positioning hole is a slotted hole. Further, each lead frame unit is provided with a plurality of third positioning holes and fourth positioning holes on the second side band, wherein the fourth positioning holes are oblong holes. Further, a first connecting rib is further arranged between two adjacent lead frame bodies. Further, the lead frame body further comprises second connecting ribs and reinforcing ribs, wherein the second connecting ribs are connected between two adjacent base islands, and the reinforcing ribs are connected between pins of two upper and lower adjacent lead frame units. Further, the lead frame body further comprises a stress release dovetail groove which is arranged between the second connecting rib and the base island. Further, the lead frame body further comprises a first V-shaped groove which is formed in the edges of the left side and the right side of the base island, wherein the first V-shaped groove is located on one surface, far away from the chip, of the base island. Furthermore, the pins are provided with circular arcs generated by stamping. The utility model has the technical effects and advantages that: 1. Through setting up lead frame unit and including first pin, second pin, third pin, fourth pin and fifth pin to be equipped with the silvering layer at the root of first pin, second pin, fourth pin, fifth pin, can form 4 welded feet at the root of first pin, second pin, fourth pin, fifth pin, compare in only setting up two welded feet, stress distribution during welding is more even, can improve the reliability of solder joint, avoids appearing stress concentration and influences the problem of lead frame performance. In addition, more fillets generally means a larger mechanical connection area, which can increase the mechanical strength of the solder joint, making it more resistant to vibration and shock. 2. The first positioning hole is mainly used for positioning the whole lead frame structure when the lead frame processing die is used for stamping and bending the lead frame structure, the second positioning hole is arranged into a long round hole, and when the lead frame structure is s