JPH06100982A - Production of lead frame material and lead frame using the same - Google Patents

Abstract

PURPOSE:To produce a lead frame material minimal in the contraction of the material even if subjected to stress relief annealing, free from deterioration in the precision of working, such as press punching, and capable of suitably performing the feed of a strip and also to produce a lead frame by using this lead frame material. CONSTITUTION:Ni content in a lead frame material composed of Fe-Ni type metallic material is regulated to 31-33wt.%. Further, a lead frame is produced by using this material and performing a press working before and after stress relief annealing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame material which is less likely to expand and contract by heating and a method of manufacturing a lead frame using the lead frame material.

[0002]

2. Description of the Related Art Conventionally, for example, in the case of manufacturing an IC lead frame, a Fe--Ni-based metal material having excellent conductivity has been used as a material. A Fe-Ni alloy strip for a lead frame, which has feed holes on both sides at regular intervals, is used.

The following method is adopted as a method for manufacturing the Fe-Ni alloy strip for the lead frame. First, a Fe-Ni alloy sheet material is hot-rolled, then cold-rolled, softened and annealed once, and then finish-rolled at a workability of 50% or less, and then sheared to a predetermined width. To produce a strip having a predetermined thickness. Then, feed holes are formed on both sides of this strip, the first press punching is performed, then the strain relief annealing is performed, and the second press punching is performed. After that, a molding process using a resin is performed.

As such a strip plate made of an Fe-Ni alloy for a lead frame, for example, a lead frame material made of an Fe-42Ni alloy, which has a small expansion coefficient and is less likely to peel off during resin molding, is usually used. ing.

[0005]

However, this F
Although the e-42Ni alloy lead frame material has a small expansion coefficient and is suitable for resin molding, it has the following problems and is not always preferable.

That is, in the manufacturing process, if strain relief annealing is performed after rolling (after press working), so-called Directio
There was a problem that the strip contracts due to the effect of nal order (the problem of heat expansion and contraction). This Directional
The heat expansion and contraction according to Order is a phenomenon in which the material whose orientation is given to the crystal by rolling loses its orientation to the crystal by strain relief annealing and becomes random, causing the dimensions to change (shrink). .

As a result, the dimensions of the strip differ before and after the stress relief annealing (for example, about 0.04%), so that the position cannot be accurately adjusted in the punching after the stress relief annealing. There was a problem that the precision of press punching was reduced. In particular, when the amount of heat expansion and contraction is large, the pitch of the feed holes provided on both sides of the strip becomes small after the strain relief annealing, and the pins for feeding the strip are removed in the next step of the strain relief annealing. In some cases, the strip could not be fed because it did not enter the feed hole.

Therefore, the present invention has been made to solve the above-mentioned problems, and the shrinkage of the material is small even if strain relief annealing is performed, the precision of processing such as press punching does not decrease, and the feeding of the strip is also suitable. An object of the present invention is to provide a lead frame material that can be used and a method of manufacturing a lead frame using the lead frame material.

[0009]

In order to achieve the above object, the present invention according to claim 1 sets a Ni content of 31 to 33% by weight in a lead frame material made of an Fe-Ni based metal material. The main feature is the characteristic lead frame material.

A second aspect of the present invention is the lead frame material according to the first aspect, further comprising 4 to 10% by weight of Co.
The main point is a lead frame material that is characterized by including it.

According to a third aspect of the present invention, in the lead frame material according to the first or second aspect, 0.1 to 0.6% by weight of at least one of Cu and Mo is further contained. The main point is the lead frame material.

According to a fourth aspect of the present invention, the lead frame material according to any one of the first to third aspects is cold-rolled, press punched and strain relief annealed, and then press punched again to form the lead frame. The gist is a method of manufacturing a lead frame, which is characterized by manufacturing.

Here, the lead frame is I
C lead frame can be mentioned. Further, as the Fe-Ni-based metal material, an Fe-Ni alloy containing Ni in the range of 31 to 33% by weight can be mentioned, and among them, N is particularly preferable.
A material having an i content of 32% by weight is suitable because the shrinkage factor during stress relief annealing is extremely small.

[0014]

The present invention was made based on the findings obtained by the present inventors as a result of repeated studies on the relationship between the Ni content and the heat expansion and contraction of Fe-Ni-based metallic materials. That is, as shown in FIG.
There is a certain relationship between the i content and the heat expansion / contraction amount, and the Ni content of 32% by weight to 31% to 33% by weight has a very small amount of heat expansion / contraction.

Therefore, according to the first aspect of the present invention, as the lead frame material made of the Fe-Ni-based metal material, the Ni content is set to 31 to 33% by weight, and as shown in FIG. Since there is little heat expansion and contraction and there is little change in dimensions during strain relief annealing, it is possible to perform accurate press working. Further, since the pitch of the feed holes of the lead frame material does not change, the feed can be performed smoothly.

Further, in the invention of claim 2, since the lead frame material according to claim 1 further contains 4 to 10% by weight of Co, the coefficient of thermal expansion is low as shown in FIG. 3 described later. Therefore, it is possible to prevent the resin from peeling off during the molding of the resin.

Further, in the invention of claim 3, the lead frame material according to claim 1 or 2 is further provided with Cu and M.
Since at least one of O is contained in an amount of 0.1 to 0.6% by weight, the corrosion resistance is improved. Further, according to the invention of claim 4, when the lead frame is manufactured, the lead frame material according to any one of claims 1 to 3 is cold rolled,
After press punching and strain relief annealing, press punching is performed to manufacture the lead frame.
There is little shrinkage of the lead frame material even after strain relief annealing,
Therefore, the precision of the press working is improved, and the lead frame material is preferably fed.

[0018]

Next, preferred examples will be described in order to further clarify the present invention. In this embodiment, a material of Fe-32 (wt)% Ni is used as the lead frame material, and the strip material 2 of the lead frame 1 shown in FIG.
Was manufactured.

Repeated annealing and rolling several times, 0.25 mm
To produce rolled material with a thickness of. After being kept at about 1000 ° C. for 5 minutes in a vacuum, it is cooled and softened and annealed. By applying a predetermined pressure, finish rolling is performed in a cold state at a workability of 50% or less to a thickness of 0.15 mm.

Shear into a predetermined width (for example, 50 mm). The feed holes 3 are formed at predetermined intervals on both sides of the strip 2. The first press punching is performed. In vacuum, the material is kept at about 600 ° C. for 5 minutes and then cooled and strain relief annealing is performed. The heat expansion and contraction before and after the stress relief annealing was almost zero.

A second press punching is performed to form a strip 2 having a large number of lead frames 1 shown in FIG. After that, the strip 2 is separated and the lead frame 1
Are separated and resin molding processing is performed.

That is, the lead frame material of this embodiment is
Since Fe-32% Ni is used as the material, the heat expansion and contraction before and after the stress relief annealing is almost zero.
Therefore, even when the press working is performed before and after the strain relief annealing, the precision of the pressing is extremely large, and the lead frame 1 having an accurate dimension can be manufactured.

At the same time, since the heat expansion and contraction is almost zero, even after the strain relief annealing, the pin of the feeding device (not shown) can be fitted into the feeding hole 3 well and the feeding operation and the press positioning can be appropriately performed. it can. (Experimental Example 1) Next, an experimental example in which it is confirmed that the Fe-Ni-based material of the present example has a small thermal expansion and contraction will be described together with a comparative example.

In this experimental example, as the Fe-Ni-based material, the Ni component was 26, 28, 30, 32, 34, 3
A strip was produced by the following procedure using 6,42% by weight of the alloy. Annealing and rolling are repeated several times to produce a rolled material having a thickness of 0.25 mm. After being kept at about 1000 ° C. for 5 minutes, it is cooled and vacuum-annealed.

Cold rolling is carried out by applying a predetermined pressure to a thickness of 0.15 mm. Strain relief annealing is performed at 600 ° C. for 5 minutes. Then, the heat expansion / contraction measurement by strain relief annealing of this strip was performed. The results are shown in FIG. 2, in which the Ni component is 32% by weight corresponds to the above embodiment, and the other Ni components are 26,
Those of 28, 30, 34, 36 and 42% by weight correspond to comparative examples.

As is clear from FIG. 2, when the material having the composition of this embodiment is used, the heat expansion and contraction is almost zero, which is extremely preferable. Further, even when Ni is in the range of 31 to 33% by weight, the heat expansion and contraction amount is It is preferably about 0.002% or less. On the other hand, in the case of the comparative example, when the weight% of Ni exceeds 34, the heat expansion / contraction amount gradually increases to exceed 0.003%, and when the weight% of Ni is less than 30, it is not preferable. It is not preferable because the amount of heat expansion and contraction rapidly increases.

(Experimental Example 2) Next, Fe-Ni of this Example
In order to reduce the coefficient of thermal expansion,
An example of an experiment in which is added will be described. A sample containing 2,4,6,8,10% by weight of Co in an Fe-32Ni alloy was produced, and a strip material was produced in the same manner as in the experimental example. 1 / ° C.]) was measured. The result is shown in FIG.

As is clear from FIG. 3, those containing 4 to 10% by weight of Co have a small body expansion coefficient of about 6 (1 / ° C.) or less, and when the resin is molded on the IC lead frame, Peeling hardly occurs, which is preferable. In addition, it is preferable that the material having the composition of the above-mentioned embodiment further contains at least one of Cu and Mo in an amount of 0.1 to 0.6% by weight because it has excellent corrosion resistance.

Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to these embodiments and can be implemented in various modes without departing from the scope of the invention. Absent. For example, the number of times of softening annealing and the number of times of press punching may be appropriately changed without any problem.

[0030]

As described above, according to the first aspect of the invention, the lead frame material made of the Fe-Ni-based metal material has a Ni content of 31 to 33% by weight, so that the stress relief annealing is performed. The heat expansion and contraction can be reduced, and therefore, the dimensional change in the strain relief annealing is small, so that accurate press working can be performed. Further, since the pitch of the feed holes of the lead frame material does not change, the material after the strain relief annealing can be fed smoothly.

Further, in the invention of claim 2, since the lead frame material of claim 1 further contains 4 to 10% by weight of Co, the coefficient of thermal expansion can be suppressed to a low level, and therefore, when molding the resin. Can be prevented from peeling off. Furthermore, in the invention of claim 3, claim 1 or claim 2
Since the lead frame material described in 1) further contains 0.1 to 0.6% by weight of at least one of Cu and Mo, there is an advantage that the corrosion resistance is improved.

According to the invention of claim 4, the lead frame material according to any one of claims 1 to 3 can be suitably manufactured.

[Brief description of drawings]

FIG. 1 is a plan view showing a shape of a strip material of a lead frame manufactured by press punching in an example.

FIG. 2 is a graph showing the relationship between the Ni content and the heat expansion / contraction amount in Experimental Example 1.

FIG. 3 is a graph showing the relationship between Co content and thermal expansion coefficient in Experimental Example 2.

[Explanation of symbols]

 1 ... Lead frame 2 ... Band material 3 ... Feed hole

Claims (4)

[Claims] 1. A lead frame material made of an Fe—Ni-based metal material, wherein the Ni content is 31 to 33 wt%. 2. The lead frame material according to claim 1, further comprising 4 to 10 wt% of Co. 3. The lead frame material according to claim 1 or 2, wherein at least one of Cu and Mo is 0.1 to 0.
A lead frame material containing 6% by weight. 4. A lead frame is manufactured by performing cold rolling, press punching, and strain relief annealing on the lead frame material according to any one of claims 1 to 3 and then press punching again. And a method for manufacturing a lead frame.