JPH055591B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to cladding materials, particularly semiconductor chips where it is necessary to partially coat a metal base material with a metal different from that of the base material at an arbitrary position. This invention relates to a method of manufacturing a cladding material using partial dissimilar metal coating for use in lead frames, heat sinks, etc.

BACKGROUND ART The following method is generally known as a method for manufacturing a partially covered cladding material of dissimilar metals as described above.

(a) Electroplating method (b) Vacuum evaporation method (c) Ion plating method (d) Rolling pressure welding method Problems to be solved by the invention However, plating in a broad sense as in (a) to (c) above When using this method, it takes a relatively long processing time to form a metal coating layer to a predetermined thickness, which not only leads to increased costs, but also has poor adhesion of the coating layer to the base material, and can be heated. It has the disadvantage that it tends to cause blisters in some cases. On the other hand, the rolling welding method described in (d) above has been proposed as a coating method that can improve the above-mentioned drawbacks.In practice, metal foil is used as the coating material, and this is applied to the base material. Since rolling is performed by placing the coating material in a desired position, there are many problems in terms of ensuring accurate positioning of the coating material, workability, etc., and it has not yet been put into practical use as a mass production technology. is the current situation.

This invention solves the above-mentioned problems and provides a method for manufacturing a partially dissimilar metal-coated cladding material, that is, a method for manufacturing a cladding material partially coated with dissimilar metals, which uses a connected treatment process to achieve high efficiency and improve the adhesion of the coating material to the base material. The purpose of the present invention is to provide a method for manufacturing a cladding material.

Means for Solving the Problems To this end, the invention provides that the metal to be coated is partially applied onto the base material by means of printing in a mixture of its powder and a binder, and then by cold rolling welding. The main purpose is to bring the base material and metal powder into pressure contact.

In other words, the method for producing a clad material according to the present invention involves screen printing a mixture of a powder of the coated metal and a binder when producing a clad material in which a predetermined position on a base material is partially coated with a dissimilar metal. The method is characterized in that the metal powder layer is partially coated on the base material by a method, and then rolled to integrate the metal powder layer with the base material, and more preferably, after the above step, the metal powder layer is applied in a vacuum. Alternatively, it is characterized by carrying out a heating diffusion treatment in an inert gas atmosphere.

In the application of this invention, common metals used as the base material include, for example:
42 alloy, Cu, Fe, SUS, etc.
On the other hand, common coated metals include, for example:
Examples include Al, Pb-Sn alloy, Ag, etc.

In addition, the binder to be mixed with the coated metal powder is one that allows the metal powder to be applied onto the base material by printing and that can temporarily maintain a certain degree of bonding force to the metal powder even after application. Any alcohol may be used, and aliphatic saturated alcohols such as decyl alcohol and undecyl alcohol, and resins can be suitably used.

When manufacturing cladding materials, first, the base material is degreased or pretreated to remove oxide film in accordance with conventional methods, and then the mixture of the metal powder and binder is adjusted to an appropriate viscosity. , Apply it to a thickness of about 10 to 30 μm by screen printing on the desired area on the base material. For continuous production of clad material, a strip of base material is continuously fed to a screen printing machine, and the above mixture is printed and applied on its surface at intervals and in a predetermined pattern. shall be taken as a thing.

In this manner, the metal powder is coated on the base material in a mixed state with the binder, and then heated to dry or evaporate the binder.
This heat drying treatment is necessary and sufficient if carried out at 150 to 300°C for about 5 to 30 minutes, but if the base material or metal powder is easily oxidized by heating, use a non-oxidizing atmosphere, That is, it is desirable to carry out the process in vacuum or in an inert gas atmosphere.

Next, the base material on which a predetermined metal powder layer has been formed as described above is rolled in accordance with a conventional method, so that the metal powder is sufficiently firmly pressed and integrated with the base material. This rolling is generally performed cold, but hot rolling is not excluded. Further, the rolling reduction ratio is preferably approximately 10 to 30%. If the rolling reduction rate is too low, there is a risk that the adhesion or bonding of the metal coating layer to the base material will be insufficient; on the other hand, if the rolling reduction rate is too high, the positional accuracy and shape accuracy of the metal coating layer will decrease. There is a risk of this happening.

In order to further improve the adhesion strength and bonding strength of the metal coating layer to the base material, it is recommended to subsequently further perform a heating diffusion treatment. This heating diffusion treatment should also be carried out in a non-oxidizing atmosphere, if necessary, depending on the properties of the metal used. Diffusion treatment conditions should also be determined to appropriate values depending on the types of base material and coating metal, taking into account the diffusivity between them; however, in the case of mutual combinations of the types of metals as exemplified above,
Generally, the heating time may be approximately 400 to 450°C for 10 to 60 minutes.

Effects of the Invention As described above, the present invention involves coating a base material by printing a metal powder in a mixed state with a binder, and then rolling and welding the powder to form a metal coating layer partially on the base material. Because it is a thing,
First of all, it enables continuous high-efficiency production of clad materials, and compared to conventional electroplating methods, vapor deposition methods, ion plating methods, etc., costs can be reduced by greatly improving mass productivity. . Moreover, since the coating metal powder is pressed and integrated with the base material by rolling, the adhesion of the metal coating is extremely good, and unlike the conventional plating method, it is not possible to apply heat or bending. It is possible to provide a high quality cladding material that does not cause blistering or peeling. Furthermore, as a means of applying metal powder,
In particular, since screen printing is used, a metal powder layer can be coated and formed on the base material with a sufficient thickness in one printing, which is advantageous in terms of production efficiency, as well as on the base material. It is possible to form a metal powder coated layer in a desired and correct pattern on any desired location, and it does not shift its position during rolling. Compared to the case of using the rolling pressure welding method, the positional accuracy of the partial metal coating can be improved, and a highly accurate partially covered cladding material can be produced and provided.

Example 42 alloy with a thickness of 0.3 mm was used as the base material, and aluminum was used as the covering material.

First, the base material 42 alloy was degreased with acetone, and then the oxide film on the surface was removed with a wire brush. On the other hand, aluminum powder as a coating material was mixed with normal decyl alcohol as a binder at a volume ratio of 1:1, and the mixture was partially printed and coated on the base material by screen printing. This coating layer is 5mm wide x 4.5mm long and has a pitch of 4.5mm in the center of the 25mm wide base material.
I went at intervals of The thickness of this coating layer is approximately 20μ.
And so.

Then, in an argon gas atmosphere, 200℃ x 15
The mixture was heated for a minute to evaporate the binder, normal decyl alcohol, and dry it.

Next, cold rolling was carried out at a reduction rate of 20% to press the aluminum powder layer onto the base material.

However, we were able to obtain a clad material in which the aluminum coating with a thickness of about 5 μm was sufficiently tightly and integrally integrated with the base material.

In addition, the above cladding material was further heated at 420°C in a vacuum.
When heated for 20 minutes, the bonding surfaces of the base material and the aluminum coating were diffused into each other, and the degree of adhesion between the two was further improved.

In addition to the 42 alloys mentioned above, Cu,
Fe, SUS is used, and in addition to the above Al, Pb is used as the coating material.
- When the same method as above was carried out using Sn alloy and Ag and sequentially combining them, it was possible to manufacture a clad material in which the covering material was sufficiently firmly bonded to the base material. It was hot.

Claims (1)

[Scope of Claims] 1. When manufacturing a clad material in which dissimilar metals are partially coated at predetermined positions on a base material, powder of the coated metal is kneaded with a binder in the form of a mixture and then coated on the base material by a screen printing method. 1. A method for producing a cladding material, which comprises applying the metal powder layer partially and then rolling it to integrate the metal powder layer with the base material. 2. When manufacturing a clad material in which dissimilar metals are partially coated at predetermined positions on a base material, a powder of the coated metal is kneaded with a binder, and a mixture is then applied partially onto the base material using a screen printing method. A method for producing a clad material, which comprises: thereafter rolling the metal powder layer to press and integrate the metal powder layer with the base material, and further subjecting the base material to a heat diffusion treatment. 3. The method for producing a cladding material according to claim 2, wherein the heating and diffusion treatment is performed in a vacuum or an inert gas atmosphere.