Pin structure for improving Mos chip assembling reliability

Abstract

The utility model relates to the technical field of chips, in particular to a pin structure for improving the assembling reliability of a Mos chip, which comprises an integrated pin and an independent pin, the tail part of the integrated pin is connected with a heat dissipation copper layer on the top surface of the Mos chip by adopting a soldering tin III, the tail part of the independent pin is connected with a semiconductor silicon wafer of the Mos chip by adopting a lead, and the tail part of the independent pin is connected with a heat dissipation copper layer on the top surface of the Mos chip by adopting a lead. The end parts of the integrated pin and the independent pin are exposed out of the packaging structure of the Mos chip, the integrated pin comprises pin bodies and a bridge, the tail parts of the three pin bodies are connected, the middle parts of the three pin bodies are connected through the bridge, the bottom surfaces of the end parts of the pin bodies are provided with grooves, and the bottom surfaces of the pin bodies and the bottom surface of the bridge are provided with welding spot contact surfaces connected with a PCB (Printed Circuit Board). Compared with the prior art, the contact area of the integrated pin and the welding point is increased, the current conduction density at the welding point is reduced, and the temperature rise of the welding point is reduced; and the structural strength of the welding spots is enhanced, the local stress of the welding spots is reduced, and the reliability of Mos chip assembling and welding is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of chips, in particular to a pin structure for improving the assembly reliability of MOS chips. Background Art

[0002] As the main control unit in the EPS system, the steering gear ECU has unquestionable safety performance requirements. The MOS chip is an important component in the ECU. The MOS chip uses SMT technology to connect the chip pins to the PCB board through solder paste welding to form a conduction loop, forming a three-phase control inverter circuit and a phase separation circuit.

[0003] Under the temperature cycle load of -40℃-110℃, the thermal expansion coefficients of the Mos chip itself, solder paste, and PCB board materials are not the same, resulting in relative deformation and stress between the chip pins and solder paste.

[0004] As the intermediate link between the chip pins and the PCB board, the solder paste solder joints are relatively weak links that are affected by the relative expansion and deformation of the MOS chip and the PCB board under temperature cycling conditions. In order to ensure the normal operation of the MOS chip function, the reliability of the solder joints is crucial.

[0005] The existing pin structure is as follows Figure 1 As shown, the pin bodies 11 are separated from each other, the bottom of the pin body 11 is connected to the PCB board by solder joints, and the solder joints are also in a state of being separated from each other. The area of ​​the solder joint contact surface 12 connecting the pin body 11 and the PCB board is about 0.9mm 2 ,like Figure 2 As shown, the smaller contact area also leads to an increase in the current conduction density and local stress concentration at the solder joint, making it difficult to ensure the reliability of the solder joint.

[0006] Therefore, it is necessary to design a pin structure that improves the reliability of MOS chip assembly, so as to increase the contact area between the pin structure and the solder joint and enhance the structural strength of the solder joint, thereby improving the reliability of MOS chip assembly welding. Summary of the invention

[0007] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a pin structure for improving the reliability of MOS chip assembly, so as to increase the contact area between the pin structure and the solder joint and enhance the structural strength of the solder joint, thereby improving the reliability of MOS chip assembly welding.

[0008] In order to achieve the above-mentioned purpose, the utility model is a pin structure for improving the reliability of MOS chip assembly, including an integrated pin and an independent pin. The tail of the integrated pin and the top heat dissipation copper layer of the MOS chip are connected by solder, and the tail of the independent pin and the semiconductor silicon wafer of the MOS chip are connected by lead wire. The ends of the integrated pin and the independent pin are exposed outside the packaging structure of the MOS chip. The integrated pin includes a pin body and a bridge. The tails of the three pin bodies are connected, and the middle parts of the three pin bodies are connected by a bridge. The bottom surface of the end of the pin body is provided with a groove, and the bottom surface of the pin body and the bottom surface of the bridge are provided with a solder point contact surface connected to the PCB board.

[0009] The bottom of the top heat dissipation copper layer is connected to the top of the semiconductor silicon chip by solder one, and the bottom of the semiconductor silicon chip is connected to the top of the base frame by solder two.

[0010] The top surface heat dissipation copper layer and the semiconductor silicon chip are located between the packaging structure and the base frame, and the top surface heat dissipation copper layer is exposed on the surface of the packaging structure.

[0011] The solder point contact surface, the independent pins and the PCB board are connected by solder points.

[0012] A downwardly bent connection structure is provided between the tail portion and the middle portion of the pin body.

[0013] Compared with the prior art, the utility model connects the pin body by bridging, so that the pin structure becomes one, which not only increases the contact area between the integrated pin and the solder joint, reduces the current conduction density at the solder joint, and reduces the temperature rise of the solder joint; it also enhances the structural strength of the solder joint, reduces the local stress of the solder joint, and improves the reliability of the MOS chip assembly welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a pin structure in the prior art.

[0015] Figure 2 It is a schematic diagram of the contact area between the pin structure and the solder joint in the prior art.

[0016] Figure 3 It is a schematic diagram of the integrated pin of the utility model.

[0017] Figure 4 It is a schematic diagram of the connection between the integrated pin and the solder joint of the utility model.

[0018] Figure 5 It is a schematic diagram of the solder joint contact surface of the integrated pin of the utility model.

[0019] Figure 6 The isometric view of a MOS chip equipped with the pin structure of the utility model is shown in FIG.

[0020] Figure 7 The exploded view is a MOS chip installed with the pin structure of the utility model. DETAILED DESCRIPTION

[0021] The utility model is now further described with reference to the accompanying drawings.

[0022] See also Figure 6 , Figure 7 The utility model is a pin structure for improving the reliability of MOS chip assembly, including an integrated pin and an independent pin. The tail of the integrated pin 1 is connected to the top heat dissipation copper layer 2 of the MOS chip by solder 7, and the tail of the independent pin 10 is connected to the semiconductor silicon chip 4 of the MOS chip by a lead 8. The ends of the integrated pin 1 and the independent pin 10 are exposed outside the packaging structure 9 of the MOS chip. The bottom of the top heat dissipation copper layer 2 is connected to the top of the semiconductor silicon chip 4 by solder 3, and the bottom of the semiconductor silicon chip 4 is connected to the top of the base frame 6 by solder 5. The top heat dissipation copper layer 2 and the semiconductor silicon chip 4 are located between the packaging structure 9 and the base frame 6 to protect the internal structure of the MOS chip. The top heat dissipation copper layer 2 is exposed on the surface of the packaging structure 9 to facilitate the heat dissipation of the MOS chip.

[0023] See also Figure 3 , Figure 5 The integrated pin 1 includes a pin body 11 and a bridge 13. The tails of the three pin bodies 11 are connected, and the middle parts of the three pin bodies 11 are connected by a bridge 13. The bottom surface of the end of the pin body 11 is provided with a groove 14. The groove 14 is convenient for solder paste to adhere and fill the bottom of the pin body 11, thereby enhancing the structural strength of the solder joint 15. The bottom surface of the pin body 11 and the bottom surface of the bridge 13 are provided with a solder joint contact surface 12 connected to the PCB board. The solder joint contact surface 12 is about 1.2mm 2 Since the current conduction density is inversely proportional to the area of ​​the solder joint contact surface 12 , as the area of ​​the solder joint contact surface 12 increases, the current conduction density at the solder joint 15 is reduced, thereby reducing the temperature rise at the solder joint 15 .

[0024] See also Figure 4 The solder joint contact surface 12, the independent pin 10 and the PCB board are connected by the solder joint 15.

[0025] A downwardly bent connection structure is provided between the tail and the middle of the pin body 11 so that the solder joint contact surface 12 at the bottom of the pin body 11 can be closer to the PCB board for easy connection.

[0026] Through simulation verification, under the same boundary conditions, the maximum stress of the solder point of the conventional pin structure is 305Mpa, and the maximum stress of the solder point of the integrated pin 1 is 250Mpa, and the maximum stress is reduced by 18%.

[0027] The utility model connects the pin bodies by bridging, so that the pin structure becomes one, which not only increases the contact area between the integrated pin and the solder joint, reduces the current conduction density at the solder joint, and reduces the temperature rise of the solder joint; it also enhances the structural strength of the solder joint, reduces the local stress of the solder joint, and improves the reliability of the MOS chip assembly welding.

Claims

1. A pin structure for improving the reliability of MOS chip assembly, including an integrated pin and an independent pin, characterized in that: The tail of the integrated pin (1) is connected to the top surface heat dissipation copper layer (2) of the MOS chip by using solder (7), the tail of the independent pin (10) is connected to the semiconductor silicon chip (4) of the MOS chip by using a lead wire (8), and the ends of the integrated pin (1) and the independent pin (10) are exposed outside the packaging structure (9) of the MOS chip. The integrated pin (1) comprises a pin body (11) and a bridge (13); the tails of the three pin bodies (11) are connected, the middle parts of the three pin bodies (11) are connected by the bridge (13); the bottom surfaces of the ends of the pin bodies (11) are provided with grooves (14); the bottom surfaces of the pin bodies (11) and the bridge (13) are provided with solder point contact surfaces (12) connected to a PCB board.

2. According to claim 1, a pin structure for improving the reliability of MOS chip assembly is characterized in that: The bottom of the top surface heat dissipation copper layer (2) is connected to the top of the semiconductor silicon chip (4) by using solder 1 (3), and the bottom of the semiconductor silicon chip (4) is connected to the top of the base frame (6) by using solder 2 (5).

3. A pin structure for improving the reliability of MOS chip assembly according to claim 2, characterized in that: The top surface heat dissipation copper layer (2) and the semiconductor silicon chip (4) are located between the packaging structure (9) and the base frame (6), and the top surface heat dissipation copper layer (2) is exposed on the surface of the packaging structure (9).

4. According to claim 1, a pin structure for improving the reliability of MOS chip assembly is characterized in that: The solder point contact surface (12), the independent pin (10) and the PCB board are connected by solder points (15).

5. The pin structure for improving the reliability of MOS chip assembly according to claim 1 is characterized in that: A downwardly bent connection structure is provided between the tail portion and the middle portion of the pin body (11).

Images