JPH01247559A - Fe-ni alloy for lead frame excellent in blanking characteristic - Google Patents

Abstract

PURPOSE:To manufacture an Fe-Ni alloy for lead frame excellent in blanking characteristic by preparing an Fe-Ni alloy which has a composition consisting of Fe and Ni in specific proportions and in which relative X-ray intensities at respective crystal planes by X-ray diffraction satisfy specific conditions. CONSTITUTION:An Fe-Ni alloy which has a composition consisting of 30-55wt.% Ni and the balance Fe with inevitable impurities and in which relative X-ray intensities by X-ray diffraction are regulated to 5-20% at the (311) plane, 30-50% at the (220) plane, 25-50% at the (200) plane, and 3-15% at the (111) plane, respectively, is prepared. By this method, the Fe-Ni alloy for lead frame having superior blanking characteristic can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a Fe for IC lead frame with excellent punchability.
-Ni alloy.

[Conventional technology]

F e -N i used for lead frames of IC etc.
As for the properties of the alloy, it has good punchability as well as
Characteristics related to surface properties such as plating properties are also becoming more important.

However, the surface quality seems to be relatively less dependent on the material, as a chemical polishing process has been introduced to ensure stable plating properties when processing the lead frame. be.

On the other hand, recent lead frames tend to have more pins and become more complex, and end users' demands regarding the shape of the lead frame after punching are becoming more stringent, or due to cost considerations, conventional etching methods are being replaced. Due to the need to change the punching method, materials with better punching properties are required.

[Problem to be solved by the invention]

Regarding the punchability of Fe-Ni alloy for lead frames,
Until now, (1) mechanical properties of the material, (2) shape (flatness), and (3) residual stress have been considered to be important factors, and improvements have been made mainly in these points.

For example, JP-A No. 62-224636, JP-A No. 61-9
No. 552, JP-A-61-6251, JP-A-61-38
No. 35 etc.

However, in a multi-pin lead frame with 40 or more pins as shown in Figure 1 (a diagram with most of the leads omitted), the width of lead 1 is extremely small and complicated, and as shown in Figures 2 and 3. Problems during punching, such as lead deviation 3 and step 4, which are differences from the normal position 2 of the lead shown in FIG. Here, the lead offset 3 is a phenomenon in which the lead intervals become uneven in a plan view, and the lead step 4 is a phenomenon in which the position changes in the vertical direction.

In view of the above points, the present invention provides Fe-Ni for lead frames.
The purpose is to improve the punchability of the alloy and reduce lead shape defects during punching.

[Means to solve the problem]

The present invention provides a lead with excellent punchability, characterized in that the relative X-ray intensity of each crystal plane according to X-ray diffraction satisfies the table below, and the lead is composed of Ni: 30 to 55 wt%, the balance being Fe and unavoidable impurities. This is an Fe-Ni alloy for frames.

In Fe-Ni alloys for IC lead frames, if Ni is less than 30 wt%, the heat treatment coefficient of the alloy becomes large;
It becomes incompatible with the coefficient of thermal expansion of the silicon chip of the IC.

Moreover, when it exceeds 55 vt%, the yield strength increases by 0.2% and the workability is significantly reduced. Furthermore, it is economically disadvantageous to contain a large amount of Ni. For this reason, Ni
The content was defined as 30wt% to 55vt%.

Fe--Ni alloys for IC lead frames are used after repeated cold rolling and intermediate annealing, followed by finish rolling, striation cutting, and stress relief, in order to improve punchability. In this state, the Fe-Ni alloy has a certain crystal orientation.

In Fe-Ni alloy, (311) is determined by X-ray diffraction.
, (220), (200), and (111) planes, and the degree of aggregation of crystal orientations can be determined. This crystal orientation changes depending on processing conditions.1 The present inventors believe that due to the difference in crystal orientation, lead deviation during punching,
It was discovered that the frequency of occurrence of defects such as deviations differs greatly.

Figure 4 shows the changes in the relative X-ray intensity of each diffraction plane when the degree of rolling is changed using an Fe-Ni alloy and when annealing is performed after that. In particular, the relative X of the (220) and (200) planes
It is clear that the line intensity changes significantly.

The present inventors have discovered that by controlling the relative X-ray intensity of this specific surface, it is possible to suppress the occurrence of defects such as a one-step difference in lead deviation during punching. That is, (
If the relative X-ray intensity of the 200) plane exceeds 50%, the illegality of the material becomes strong, and it is easy to cause a one-step difference in lead deviation during punching. In addition, the relative X-ray intensity of the (220) plane is strong, the anisotropy increases, and lead shape defects are likely to occur during punching.

From the above points, the relative X-ray intensity of the (200) plane is set to 25~
The range was set at 50%. Other relative X-ray intensities that satisfy the specified range of the relative X-ray intensity of the (200) plane and do not cause lead deviation or step defects during punching are the (220) plane,
30 to 5 for (311) plane and (111) plane, respectively.
0%.

5 to 20% and 3 to 15%, and these ranges were defined.

〔Example〕

The present invention will be explained below based on one embodiment.

By changing the processing conditions of a Fe-Ni alloy for IC lead frames consisting of 42vt% Ni, the balance being Fe and unavoidable impurities, we produced a material with the relative X-ray intensity shown in Table 1. The lead frame shown in FIG. 1 was punched, and an investigation was conducted regarding lead offset of 3 and level difference of 4. The results are also shown in Table 1.

As is clear from Table 1, in the alloy of the present invention, both the lead deviation 3 and the lead height difference 4 after punching can be made less than 0.1 square inch, and the punching performance as a lead frame is good. Ta. On the other hand, the comparative alloy had a large lead deviation 3 and a large lead height difference, which caused problems in punchability.

The relationship between the relative X-ray intensity and the lead deviation 3 and the lead height difference 4 is the same even if the Ni content is changed,
The range of relative X-ray intensity is (311) (220) (200
) (111) plane, respectively, 5 to 20.30 to 5
If the range of 0.25-50.3 to 15% was satisfied, the punchability was good.

〔Effect of the invention〕

According to the present invention, by specifying the relative X-ray intensity with respect to the diffraction surface, an Fe-Ni alloy for lead frames having good punchability can be obtained, and it is possible to obtain a Fe-Ni alloy for lead frames having good punchability. Even when the lead frame is blanked, the deviation of the leads and the level difference in the leads can be sufficiently tolerated, and the quality of the lead frame is greatly improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing one form of the lead frame, Figure 2 is an explanatory diagram closer to the lead, Figure 3 is an explanatory diagram of the step of the lead, and Figure 4 is the relationship between X-ray intensity and rolling and annealing for the diffraction plane. FIG. 1: Lead, 2: Normal position, 3: Lead bias. 4: Lead step diagram 1

Claims (1)

[Claims] 1 Fe for lead frames with excellent punchability, characterized in that the relative X-ray intensity of each crystal plane according to X-ray diffraction satisfies the table below, and consists of Ni: 30 to 55 wt%, the balance Fe and unavoidable impurities. -Ni alloy.