JPS6021825B2 - Manufacturing method of tin-lead clad plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a tin-lead clad plate, and more particularly to a method of joining both metal plates by diffusion without plastic deformation.

Generally, the manufacturing method of clad plate is rolling method, post-blow method,
Welding methods, brazing methods, plating methods, plating methods, etc. are known, but for example, by disposing pure b or Pb-rich phase Pb-Sn alloy (hereinafter simply referred to as Pb-rich phase alloy) in the middle, In the case of a three-layer clad plate with a structure in which both sides are coated with a Sn-Pb alloy (hereinafter simply referred to as Sn-rich phase alloy), the rolling method is the most common method among the various methods mentioned above. Adopted as.

However, in the case of the rolling method, the deformation resistance of the Sn-rich alloy and the Pb-rich alloy is significantly different, which tends to cause the so-called "ribble" phenomenon in which the joint interface becomes undulating during rolling. The thickness becomes uneven depending on the location, and if this phenomenon progresses further, the coating layer may break and the core material of the Pb-rich phase alloy may be exposed. In addition, in order to metallurgically join two metal plates by rolling, it is necessary to roll with a large reduction at once, but in order to realize this type of operation, the rolling rolls must be There are also equipment problems, such as the need for special rolling equipment that can apply pressure to In view of the above points, the present invention has been made with the aim of providing a method for manufacturing a tin-lead clad plate in which each layer has a uniform thickness and is easy to manufacture. It is possible to widen the range of components and thicknesses of the constituent materials, which have been restricted, and increase the types of cladding materials, and it is also possible to improve the adhesive force between both metals without using pressure.

In the case of the rolling method, it is necessary to apply large plastic deformation to the component materials by the pressure applied by the rolls, thereby exposing the active matrix at the contact surface of both component materials and forming a bond between the atoms of both metals at the contact surface. Although welding is performed close enough to allow mutual forces to act, if there is a significant difference in the degree of plastic deformation of each constituent material when pressure is applied, this may cause the deformation as described above. A problem arises in that the thickness of each constituent material after being bonded is not uniform. Therefore, in the present invention, the two constituent materials are brought into sufficient contact with each other to metallurgically join them by diffusion without giving large plastic deformation to the constituent materials.

Conventionally, when bonding Pb alloys, there has been a problem in that the oxides on the surface are extremely ductile, so if the Pb alloys are simply brought into close contact with each other in a solid state, the oxides become an obstacle to diffusion, making it difficult to bond. Therefore, in order to destroy oxides and promote diffusion, it was believed that a rolling method that could provide the large plastic deformation necessary for this purpose was appropriate.

In response to such conventional technology, the present inventors conducted more detailed research on the state of existence and adhesion of oxide films in Pb alloys, and found that the presence of oxide films on the surface could be reduced to below a certain limit by appropriate pretreatment. If it is possible to do so, it is possible to bond the Pb alloy with other metals such as Sn alloys by diffusion in the open phase state simply by keeping the Pb alloy in a close contact state without substantially imparting plastic deformation. It has been made clear.

Therefore, the gist of the present invention is to prepare pure Pb or Pb-rich Pb-
Bonding the Sn alloy plate and the pure Sn or Sn-rich phase Sn-Pb alloy plate by diffusion by pressurizing and adhering both of the plates without substantially plastically deforming them and maintaining that state for a predetermined period of time. It is in.

In the present invention, pressure is necessary to maintain the close contact between the two metal plates, and therefore, there is no need for pressure large enough to cause plastic deformation as in the rolling method.

In the present invention, sufficient bonding is possible with a pressure of about 2.5 kg/g at room temperature. In addition, in the present invention, the higher the temperature, the more diffusion is promoted, so it is preferable that the temperature is higher.
This makes it possible to further reduce the pressing force and create a situation where bonding is easier. However, since the eutectic point of the Sn-Pb alloy is 3 at 183° C., it is desirable to perform the bonding at a temperature of 18yo or less in order to perform solid phase bonding without the risk of forming an intermetallic compound. Next, an embodiment of the method for manufacturing a tin-lead clad plate according to the present invention will be described with reference to the accompanying drawings.

This cladding 4 plate is used, for example, as cladding solder for semiconductor devices to bond semiconductor elements. In Figure 1, a Pb plate 1 with a thickness of 8 mm, whose surface oxide film has been removed by brushing in advance, and 3 layers each of S plates 2 and 3 with a thickness of 0.26 mm are combined. /The plates were brought into close contact with each other using the pressure of the fence, and held in this state for 5 minutes to bond each plate by diffusion.

In the clad plate thus obtained, each twill layer was metallically bonded to each other, and the thickness of each layer was uniform. Furthermore, when the same treatment as above was carried out at 150 qo, the constituent layers were metallurgically bonded to each other and the thickness of each plate was uniform, and furthermore, no reaction layer due to intermetallic compounds was observed at the bonding interface. There wasn't.

FIG. 2 shows the relationship between various temperatures (pressing temperature), adhesion pressure, and diffusion bonding state when the adhesion time is 5 minutes in manufacturing a clad plate having the structure shown in FIG. The shaded area is the area with good adhesion. Therefore, the higher the adhesion pressure is, the more preferable it is, but if the pressure is too high, macroscopic plastic formation may proceed and the plate thickness composition ratio may become non-uniform. In FIG. 2, the boundary between a region with good adhesion and a region with insufficient adhesion changes depending on the diffusion time and the composition of Pb and Sn.

In this example, when the joint area of each plate is large,
There is a risk that air will be trapped at the bonding interface during close contact.

This surrounding air causes blisters when heated. In such a case, each plate may be vacuum-packed with an airtight material such as a non-conducting plastic sheet to remove air at the interface when the plates are brought into close contact with each other. As is clear from the above invention, according to the method for producing a tin-lead clad plate of the present invention, a pure Pb or Pb-rich Pb-Sn alloy plate from which an oxide film has been removed by pretreatment and a Taito n or S
Since the n-rich phase Sn-Pb alloy plates are pressed and brought into close contact with each other without substantially plastic deformation, and this state is maintained for a predetermined period of time, the two metal plates are bonded by diffusion. Since no pressure is used, the metal plates can be easily joined without substantially plastically deforming them, and therefore, there is no ripple phenomenon, and the thickness of both metal plates can be kept uniform after joining.
It is possible to expand the range of components and thickness of the metal plate and increase the types of Pb-Sn clad plates.

Further, according to the present invention, since large-scale equipment related to rolling is not required, it is possible to reduce manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the method for manufacturing a tin-lead clad plate according to the present invention, and FIG. 2 is a characteristic diagram of adhesion by diffusion. 1...Pb board, 2, 3...Sn board. Gar diagram naz diagram

Claims (1)

[Claims] 1 Pure Pb or Pb from which the oxide film has been removed by pretreatment
Rich Pb-Sn alloy plate and pure Sn or Sn rich Sn-Pb
Manufacture of a tin-lead clad plate characterized in that both metal plates are bonded by diffusion by pressurizing the alloy plates to bring them into close contact without substantially plastically deforming them, and maintaining this state for a predetermined period of time. Method.