JPS5810844A - Manufacture of special-formed cross section strip material for lead base - Google Patents

Abstract

PURPOSE:To obtain the lead base having excellent mechanical strength and radiant characteristic by continuously joining the side sections of thin blanks to the side section of a thick blank having superior thermal conductivity through welding. CONSTITUTION:An oxygen-free copper material is used as the thick section 10, a phosphor bronze material is emploved as the thin sections 20, these blanks are spiral, and drawn out of guide rolls 3, 4, the one side side sections of the blanks 21 for the thin sections are passed under a welder 5 while being positioned in parallel and adjoined to the predetermined positions of both side sections of the blank 11 for the thick section, and the blanks 11, 21 are hardly melted and joined at approaching surface sections.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention primarily relates to a method of manufacturing a strip of irregular cross section for lead paste used in semiconductor devices such as power transistors.

As shown in Fig. 1 (a) and (b), the irregular cross-section strip material for the lead pace is used in which (i!!m) is thinner than other parts, but both parts have different required characteristics depending on their intended use.In other words, thin-walled MS2
Since it becomes a lead terminal part, mechanical strength such as hardness and repeated bending strength is required.

On the other hand, the thick portion 1 serves as a heat sink portion on which a silicon pellet, which is a semiconductor element, is placed, and therefore requires excellent thermal conductivity.

Conventionally, this type of strip material was obtained by rolling or cutting the same material, so each part has almost the same characteristics, and in practical terms, the design focuses on one of the characteristics and the other. I had to make some sacrifices.

In order to improve this drawback, a method has also been proposed in which the thin-walled portion 2 is compression-molded by press compression to improve the processing efficiency of the thin-walled portion 2. However, this method has the drawback that the stress within the material cannot be balanced after processing, and a correction process is required to obtain a normal shape, as well as the accuracy is unstable.

This invention was made to eliminate the above-mentioned conventional drawbacks, and is characterized by using materials that meet the required characteristics of each part, and by bonding and bonding the sides of the materials together by welding.

In this case, two types of materials are required, one for thick-walled parts and one for thin-walled parts, but metals with excellent thermal conductivity, such as oxygen-free copper and deoxidized copper, are required for thick-walled parts. Those to which a trace amount of alloying elements are added are used. For thin-walled trenches, materials that meet the required characteristics, such as 190 alloy and 194
Alloy, 195 alloy, nickel silver, red copper, cupronickel, F
e-42Ni, Kovar, iron, etc. are used, but in the case of
Depending on the case, the same material as for the thick portion may be used.

TIG welding, M/G welding, plasma welding, electron beam welding, laser welding, etc. are used to weld these two materials.

The following explanation will be given with reference to the drawings.
) show examples of strips manufactured according to the present invention, in which oxygen-free steel is used for the thick wall portion 10 and phosphor bronze material is used for the thin wall portion 20.

When manufacturing any of the examples of strips, as shown in FIG.
1 and 21 are used in a coiled form.

Thus, each of the materials 11 and 21 was pulled out from the coil by the guide roll 3.4, and brought close to each other so that the one side of the material 21 for the thin part was aligned with the predetermined positions of both measuring parts of the material 11 for the thick part. It passes under a welding device 5 such as electron beam welding. When the strip has a shape as shown in FIG. 2, the sides of the material 21 are bent until the welding point is reached.

By passing through 5 parts of the welding device, the materials 11 and 21
are firmly joined at the approach surface with almost no melting.

In this case, this can be achieved by adjusting the welding current, speed, electrode diameter, etc.

The welded strip is then finished by rolling, heat treatment, etc., or used as a lead base material.

In this example, the two thin-walled materials 21 are replaced by the thick-walled materials 11.
Although the case where welding is performed at the same time is shown, the positions of the welding devices 5 for each helmet may be shifted, or the parts of one welding device 5 may be passed twice on each side.

As is clear from the above explanation, according to the method of the present invention, not only can a long product be obtained without the need for complicated processes, but also a long product can be obtained that has the characteristics required as a strip material for lead base. It has the advantage of being able to provide the most suitable materials.

[Brief explanation of drawings]

FIGS. 1(A) and 1(B) are perspective views showing examples of conventional lead base strips, and FIGS. 2(A) to 2(S) show examples of lead base strips according to the present invention. 1 and 3 are explanatory diagrams showing an example of the manufacturing method of the present invention. 1 and 10: thick part, 2 and 2o: thin part, 3 and 4 guide rolls, 5: welding device, 11: material for thick part, 2
1: Material for thin parts. / T 4-59

Claims (1)

[Claims] 1. It is characterized by the fact that the side of a thinner material is brought closer to the side of a thicker material with good thermal conductivity, and the approaching sides are continuously joined by welding. A method for manufacturing a strip of irregular cross section for lead pace.