Silver-copper solder and kovar alloy pre-welding tool

Abstract

The utility model discloses a silver-copper solder and kovar alloy pre-welding tool which comprises an upper cover, a base and a pressing block insert, a plurality of first sinking grooves used for containing a lead frame are formed in a base body of the base at intervals, a second sinking groove is formed in the middle of the first sinking grooves, a third sinking groove is formed in the middle of the second sinking groove, and the pressing block insert is arranged in the third sinking groove. A through hole is formed in the middle of the third sinking groove; the pressing block insert is embedded in the second sinking groove; a plurality of convex blocks are arranged on the bottom wall of the first sinking groove, and the width of the convex blocks is limited by the fact that the convex blocks are attached to two adjacent pins when the lead frame is placed in the first sinking groove; the pressing block insert is provided with a first pressing block boss and a second pressing block boss, and the second pressing block boss fills a gap between the two pin arrays; the bottom of the upper cover body is provided with a plurality of upper cover bosses in a shape similar to a Chinese character'tu ', wherein the upper cover bosses are used for positioning the pin array. The tool is simple in structure and easy to machine, and the pre-welding efficiency of the silver-copper brazing filler metal and the kovar alloy accessory is improved.

Description

Technical Field

[0001] The utility model relates to the field of semiconductor manufacturing, and particularly relates to a pre-welding tooling for silver-copper solder and kovar alloy. Background Art

[0002] With the continuous improvement of the performance requirements of electronic products in various aspects, ceramic packaging shells have been widely used in high-reliability and high-power electronic devices. Since the chip not only requires the packaging shell to ensure mechanical protection and reliable sealing, but also needs to have good electrical conductivity and heat dissipation ability with the outside world, it is required that the ceramic can be well sealed with different metals. Among them, after metallizing the ceramic surface, the brazing process is used to braze and seal the ceramic with kovar alloy fittings. To achieve the brazing and sealing of the ceramic and kovar alloy fittings, the selection of the brazing solder is particularly important. Silver-based brazing filler metals can be one of the directions for the selection of brazing filler metals. Among them, the most commonly used is the eutectic Ag72Cu28 alloy brazing filler metal. The melting point of this silver-copper alloy is 780 °C. It not only has excellent process performance, such as suitable melting point, good wettability, strong gap filling ability, etc., but also has high welding quality and can form a brazed joint with high strength, high electrical conductivity and corrosion resistance. However, in the actual brazing process, since the silver-copper alloy often exists in a relatively thin state on the packaged product, there are process difficulties such as difficult assembly and difficult positioning, resulting in welding failure of the product.

[0003] To overcome the above process difficulties, the applicant innovated the process. First, the silver-copper solder and the kovar alloy fittings were pre-welded into one at a suitable temperature, and then the kovar alloy with the silver-copper solder and the ceramic were welded, solving the problem of difficult positioning and greatly improving the assembly efficiency. To match the process and improve the pre-welding efficiency of the silver-copper solder and the kovar alloy fittings, it is necessary to develop a special tooling for pre-welding the silver-copper solder and the kovar alloy fittings. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a pre-welding tooling for silver-copper solder and kovar alloy.

[0005] The technical solution for achieving the purpose of the present utility model is: a pre-welding tooling for silver-copper solder and kovar alloy, which includes an upper cover, a base, and a press block insert. The base includes a base body, and several first sinking grooves for accommodating lead frames are spacedly arranged on the base body. A second sinking groove is downwardly opened in the middle of the first sinking groove, a third sinking groove is downwardly opened in the middle of the second sinking groove, and a through hole penetrating the base is opened in the middle of the third sinking groove. A silver-copper brazing filler metal ring and a kovar frame are stacked and embedded in the third sinking groove from top to bottom. The press block insert is embedded in the second sinking groove. The lead frame includes a frame body and two oppositely arranged pin arrays respectively connected to the frame body. Each pin array includes several spaced pins. The first sinking groove has a first sinking groove bottom wall, and several convex blocks are arranged in the placement area of the pin array on the first sinking groove bottom wall. The convex blocks are arranged in parallel, and the convex blocks are distributed between two adjacent pins. The width of the convex block is limited by that when the lead frame is placed in the first sinking groove, the two side surfaces in the width direction of the convex block are respectively in contact with two adjacent pins. The press block insert has a press block front surface and a press block back surface. A first press block boss is arranged at the center of the press block front surface, and a second press block boss is arranged at the center of the press block back surface. The first press block boss passes through the central holes of the silver-copper brazing filler metal ring and the kovar frame. The press block front surface is in contact with the silver-copper brazing filler metal ring, and the second press block boss fills the gap between the two pin arrays. The upper cover includes an upper cover body, and several "convex"-shaped upper cover bosses for positioning the pin arrays are spacedly arranged at the bottom of the upper cover body. The contour and thickness of the upper cover boss are limited by that the upper cover body and the base body can be buckled, and when buckled, the upper cover boss is embedded in the first sinking groove and is opposite to the placement area of the pin array on the first sinking groove bottom wall.

[0006] Further, the protruding part of the "convex"-shaped structure is several convex platform arms arranged in a zigzag pattern, and the width of the convex platform arm is greater than the distance between two adjacent pins.

[0007] Further, several grooves are evenly opened on the peripheral wall of the second press block boss. The grooves opened on the peripheral wall can increase gas flow and make the overall temperature uniform.

[0008] The tooling of the present utility model is specifically used for the pre-welding of the silver-copper brazing filler metal ring and the kovar frame, as well as the silver-copper solder sheet and the lead frame. The tooling has a simple structure, is easy to process, and improves the efficiency of the pre-welding of the silver-copper solder and the kovar alloy fittings. Description of the Drawings

[0009] Figure 1 It is a three-dimensional structural schematic diagram of the pre-welding product of the silver-copper solder sheet and the lead frame according to the embodiment of the present utility model;

[0010] Figure 2 A top view structural schematic diagram of the silver-copper brazing ring and the pre-welded product of the kovar frame according to the embodiment of the present utility model;

[0011] Figure 3 A three-dimensional structural schematic diagram of the upper cover according to the embodiment of the present utility model;

[0012] Figure 4 A three-dimensional structural schematic diagram of the press block insert according to the embodiment of the present utility model;

[0013] Figure 5 A three-dimensional structural schematic diagram of the base according to the embodiment of the present utility model;

[0014] Figure 6 A top view structural schematic diagram of the base according to the embodiment of the present utility model;

[0015] Figure 7 A three-dimensional structural schematic diagram of the lead frame embedded in the base according to the embodiment of the present utility model. Detailed implementation manners

[0016] The following further describes the preferred embodiments of the present utility model in detail with reference to the accompanying drawings.

[0017] This embodiment Figure 1 Illustrates the pre-welded product structure of the lead frame 10 and the silver-copper brazing solder sheet 20. The lead frame 10 includes a frame body 101 and two relatively arranged pin arrays 102 respectively connected to the frame body 101. Each pin array 102 includes several spaced pins 1021. The silver-copper brazing solder sheet 20 is located on the brazing surface required below the pin array 102.

[0018] This embodiment Figure 2 Illustrates the pre-welded product structure of the silver-copper brazing ring 30 and the kovar frame 40. The silver-copper brazing ring 30 and the kovar frame 40 are stacked, and a central hole 401 is provided in the middle of the silver-copper brazing ring 30 and the kovar frame 40.

[0019] Such as Figures 1 to 7As shown in the figure, a pre-welding tooling for silver-copper solder and kovar alloy includes an upper cover 1, a base 2, and a press block insert 3. The base 2 includes a base body 21, and several first sinking grooves 22 for accommodating lead frames are spaced apart on the base body 21. A second sinking groove 23 is formed in the middle of the first sinking groove 22, and a third sinking groove 24 is formed downward in the middle of the second sinking groove 23. A through hole 241 penetrating the base is formed in the middle of the third sinking groove; the first sinking groove 22 has a first sinking groove bottom wall 221, and several bumps 222 are arranged in the placement area of the pin array 102 on the first sinking groove bottom wall 221. Each of the bumps 222 is arranged in parallel, and the bumps 222 are distributed between two adjacent pins 1021. The width of the bumps 222 is limited by the fact that when the lead frame 10 is placed in the first sinking groove 22, the bumps 222 are in contact with two adjacent pins 1021.

[0020] As Figure 4 and Figure 7 shown in the figure, the press block insert 3 has a press block front surface 31 and a press block back surface 32. A first press block boss 33 is arranged at the center of the press block front surface 31, and a second press block boss 34 is arranged at the center of the press block back surface 32. A silver-copper solder ring 30 and a kovar frame 40 are stacked and embedded in the third sinking groove 24 from top to bottom. The press block insert 3 is embedded in the second sinking groove 23. The first press block boss 33 passes through the center holes 401 of the silver-copper solder ring 30 and the kovar frame 40. The press block front surface 31 is in contact with the silver-copper solder ring 30. The second press block boss 34 fills the gap between two pin arrays 102, and several grooves 342 are evenly formed on the peripheral wall 341 of the second press block boss 34.

[0021] As Figure 3 shown in the figure, the upper cover 1 includes an upper cover body 11. Several convex-shaped upper cover bosses 111 for positioning the pin array 102 are spaced apart at the bottom of the upper cover body 11. The contour and thickness of the upper cover bosses 111 are limited by the fact that the upper cover body 11 and the base body 21 can be buckled, and when buckled, the upper cover bosses 111 are embedded in the first sinking groove 22 and are opposite to the placement area of the pin array 1021 on the first sinking groove bottom wall 221; the protruding parts of the convex-shaped are several convex platform arms 1111 arranged in a zigzag pattern, and the width of the convex platform arms 1111 is greater than the distance between two adjacent pins 1021.

[0022] During use, first place the silver-copper solder ring and the kovar frame in the third sinking groove in sequence, then place the lead frame in the first sinking groove, place the silver-copper solder sheet at the position of the surface to be soldered of the lead frame, then buckle the press block insert into the second sinking groove, and finally buckle the upper cover and the base.

[0023] The main function of the upper cover in this embodiment is to compact and flatten the lead frame, preventing the metal lead frame from deforming due to stress at high temperature during the pre-welding process, which may lead to poor brazing accuracy or even welding failure in the subsequent process; the main function of the press block insert is to compact and flatten the kovar frame, preventing the kovar frame from deforming due to stress relief at high temperature during the pre-welding process, which may lead to poor brazing accuracy or even welding failure in the subsequent process. In addition, the press block insert also provides a limit for the lead frame and the silver-copper filler metal solder sheet, ensuring that the silver-copper filler metal solder sheet is evenly attached to the brazing surface of the lead frame; the base ensures that the kovar frame is in close contact with the silver-copper filler metal ring and is evenly heated and eutectic during the pre-welding process, ensuring that the silver-copper filler metal ring is evenly attached to the upper surface of the kovar frame.

[0024] The utility model solves the problem of difficult assembly of silver-copper filler metal in actual production. At the same time, it ensures that the silver-copper filler metal ring is evenly and flatly attached to the welding surface of the kovar frame, providing a better brazing environment for the subsequent brazing process. In addition, after one pre-welding of the silver-copper filler metal ring, it shows better weldability in the subsequent brazing. Since the kovar frame has been wetted once, the weld seam is more delicate and flat, which can improve the sealing performance of the subsequent brazed product.

[0025] The structure of the upper cover described in the utility model is not limited to that shown in the embodiment. The serrated arrangement of the convex parts in the shape of a "convex" character is conducive to increasing gas flow; the peripheral wall structure of the second press block boss is not limited to that shown in the embodiment. The grooves opened on the peripheral wall can increase gas flow and evenly distribute the overall temperature.

[0026] The above are only the embodiments of the utility model, and do not limit the patent scope of the utility model. Any equivalent process transformation made by using the content of the specification of the utility model, directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the utility model.

Claims

1. A pre-welding tooling for silver-copper solder and kovar alloy, characterized in that: It includes an upper cover, a base, and a press block insert. The base includes a base body, and several first sinking grooves for accommodating a lead frame are spaced apart on the base body. A second sinking groove is opened downward in the middle of the first sinking groove, a third sinking groove is opened downward in the middle of the second sinking groove, and a through hole penetrating the base is opened in the middle of the third sinking groove. A silver-copper brazing ring and a kovar frame are stacked and embedded in the third sinking groove from top to bottom. The press block insert is embedded in the second sinking groove. The lead frame includes a frame body and two oppositely arranged pin arrays respectively connected to the frame body. Each pin array includes several spaced pins. The first sinking groove has a first sinking groove bottom wall, and several bumps are arranged in the placement area of the pin array on the first sinking groove bottom wall. The bumps are arranged in parallel, and the bumps are distributed between two adjacent pins. The width of the bumps is limited by that when the lead frame is placed in the first sinking groove, the two side surfaces in the width direction of the bumps are respectively in contact with two adjacent pins. The press block insert has a press block front surface and a press block back surface. A first press block boss is arranged at the center of the press block front surface, and a second press block boss is arranged at the center of the press block back surface. The first press block boss passes through the center holes of the silver-copper brazing ring and the kovar frame. The press block front surface is in contact with the silver-copper brazing ring, and the second press block boss fills the gap between the two pin arrays. The upper cover includes an upper cover body, and several "convex"-shaped upper cover bosses for positioning the pin arrays are spaced on the bottom of the upper cover body. The contour and thickness of the upper cover bosses are limited by that the upper cover body and the base body can be buckled, and when buckled, the upper cover bosses are embedded in the first sinking groove and are opposite to the placement area of the pin array on the first sinking groove bottom wall.

2. The pre-welding tooling for silver-copper solder and kovar alloy according to claim 1, characterized in that: The protruding parts of the "convex"-shaped are several convex platform arms arranged in a zigzag pattern, and the width of the convex platform arms is greater than the distance between two adjacent pins.

3. The pre-welding tooling for silver-copper solder and kovar alloy according to claim 1, characterized in that: Several grooves are evenly opened on the peripheral wall of the second press block boss.

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