JPH05283595A - Manufacture of lead frame material - Google Patents

Abstract

PURPOSE:To manufacture a lead frame material having excellent soldering and plating characteristics by rotating a brush made by wires of metal such as Cu and Ni to strongly hit a band plate of stainless steel with the end portions of metal wires. CONSTITUTION:While a band plate of stainless steel 5 is supplied from a supply reel 1 and it is wound around a take-up reel 2, a brush 3 made of Cu or Ni wire is rotated and the end portion of the rotating wires is caused to hit the band plate of stainless steel 5. Thereby, Cu or Ni is adhered to the surface of the band plate 5. Thereafter, the band sheet is rolled by rolls 4 to make smooth the surface of adhered Cu layer 7 or Ni layer 6. Thereby, a lead frame having excellent soldering and plating characteristics can be obtained, without plating work, mainly using a stainless steel in place of inver alloy as a material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lead frame material for an IC, which is made of stainless steel, and provides a lead frame material excellent in solderability and plating property.

[0002]

2. Description of the Related Art As a well-known lead frame material for ICs, Fe is known as a low expansion alloy.
A -42Ni (Invar) type alloy is widely used. In order to meet the demand for cost reduction accompanying the widespread use of ICs, a cheaper lead frame material has been demanded, and use of stainless steel has been attempted.

However, since stainless steel is inferior to Invar alloy in solderability and plating property, it is necessary to use Cu or Ni plating on the surface, and such a processing step increases the cost, and the difference in the price of the material at the corner. Will result in not being able to utilize. As a stainless steel having relatively excellent solderability and plating property, the applicant has proposed a lead frame material using chromium-based stainless steel having Fe-7Cr as a basic composition (Japanese Patent Laid-Open No. 61-284948).
This is also used as a lead frame material. Ni or C
u plating is performed.

Further, it is preferable that a part of the lead frame material is plated with Cu or Ni, and the surface of the stainless steel is rather exposed in the remaining part. However, it is rather troublesome to plate the limited part. However, if it is done carefully, it will be a factor that further increases the cost.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is a lead frame material made of stainless steel, which has a coating layer of Cu or Ni on a required portion of the surface, and therefore has a solderability and a plating property. An object of the present invention is to provide a method for manufacturing an excellent product without using plating.

[0006]

According to the present invention, there is provided a method for producing a lead frame material having excellent solderability and plating property, which comprises rotating a brush made of a wire made of Cu and / or Ni and rotating the brush made of stainless steel. By impinging the end of the wire on the strip, Cu and / or Ni are deposited on the surface of the strip, and then rolling is performed by a roll to remove the surface of the deposited Cu layer and / or Ni layer. It consists of smoothing.

Although the stainless steel strip can be selected from any material, the present invention is of great significance when a chromium-based stainless steel, typically Fe-7Cr alloy, is targeted.

[0008]

When a brush made of a metal wire such as Cu or Ni is rotated at high speed and the end of the wire is strongly hit against the stainless steel strip, the phenomenon of so-called "scratch seizure" occurs, The edges become streaks and adhere to the strip.

[0009]

EXAMPLE As shown in FIG. 1, a stainless steel strip is unwound from the unwinding device (1) and is wound by the other winding device (2) while being made of Cu and / or Ni.
The brush (3) made of wire made of steel is rotated to collide the end of the wire with the stainless steel strip (5), thereby depositing Cu and / or Ni on the surface of the strip, and then rolling. The surface of the Cu layer (7) and / or the Ni layer (6) attached by rolling according to (4) was smoothed.

In order to deposit Cu and Ni efficiently,
It is desirable to impact the ends of the wires that make up the brush against the strip. From this point of view, a brush having a cylindrical outer shape, in which the wire extends radially from the shaft, is suitable, and this type of brush strongly rotates the end of the wire by rotating the wire at a high speed around the shaft. Since it can be struck, the wire metal adheres quickly to the strip plate.

Since the adhered metal is a collection of streak marks burned as described above, the surface is not smooth and there are cavities inside. Therefore, by lightly rolling using a rolling roll (4), the surface is smoothed to keep the plate thickness constant and the inside of the layer is made dense.

The amount of metal deposited is determined by factors such as the diameter of the metal wire forming the brush, the pressure with which the brush is pressed, the rotational speed of the brush, and the contact time of the brush or the number of repetitions. Therefore, the operating conditions should be selected so as to obtain the desired deposition amount.

To show typical conditions when using a brush made of Cu, it is preferable that the Cu wire constituting the brush is pure copper or Cu having a softness of 98% or more, and a wire diameter of 0.
It is preferable that the peripheral surface density of the brush reaches 60 to 80% when the brush diameter is 2 to 2.0 mm and the brush diameter is about 100 mm. The condition of the brushing, that is, the work of rotating the brush and causing the end of the wire to collide with the strip plate is as follows: the pressing pressure is 1 to 10 Kgf /
mm and a rotation speed of 1000 rpm are typical.

It is suitable to carry out the roll rolling under the conditions of a roll speed (rolling speed of the strip 20 m / min) and a rolling reduction of 20% or more.

The present invention can be carried out in various forms, not only by forming a Cu layer or Ni layer on a stainless steel strip as required, but also by first contacting a brush of Ni wire, Further, two rolls of a Ni layer and a Cu layer existing thereon can be formed by rolling the roll after bringing it into contact with a brush of Cu wire. Figure 2
FIG. 3 is a view showing a cross section of a lead frame material of the present invention in which a Cu layer is formed by the method of FIG. 1, and FIG. 3 is a view showing a cross section of a lead frame material in which a Cu layer is formed on a Ni layer. ..

The Cu and / or Ni layer can be formed at any position on the stainless steel strip with any width by appropriately choosing the width of the brush.

[0017]

According to the method of the present invention, the surface of a stainless steel strip has a desired position and spread, and a Cu layer or a Ni layer can be easily formed to a certain range with an arbitrary thickness. Lead frame materials that can be quickly formed and have excellent solderability and plating properties can be manufactured. Since the material of the strip is stainless steel, and the manufacturing process is simple as described above, the cost of this lead frame material can be low.

[Brief description of drawings]

FIG. 1 is a conceptual explanatory view showing a typical aspect of a method for manufacturing a lead frame material of the present invention.

FIG. 2 is an enlarged cross-sectional view of an example of a lead frame material manufactured by the method of the present invention.

FIG. 3 is an enlarged cross-sectional view of another example of a lead frame material manufactured by the method of the present invention.

[Explanation of symbols]

 1 Feeding Device 2 Winding Device 3 Wire Brush 4 Rolling Roll 5 Stainless Steel Strip 6 Ni Layer 7 Cu Layer

Claims (3)

[Claims] 1. A Cu and / or Ni wire is made to strike the end of the wire by rotating a brush made of Cu and / or Ni wire to cause the Cu and / or Ni wire to strike the surface of the steel strip. Manufacture of a stainless steel lead frame material having excellent solderability and plating property, which comprises smoothing the surface of the Cu layer and / or Ni layer that is adhered and then rolled by a roll. Method. 2. The method according to claim 1, wherein chromium-based stainless steel is used as the stainless steel strip. 3. The manufacturing method according to claim 1, wherein a strip of Cu and / or Ni is provided on a part of the strip by using a brush having a width smaller than the width of the strip of stainless steel.