JPH11293408A - Iron-nickel series alloy thin sheet for electronic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an Fe-Ni series alloy thin sheet for electronic parts excellent in press punchability. SOLUTION: This alloy thin sheet is the one having a compsn. contg., by weight, 30 to 55% Ni (or 27 to 52% Ni, <=22% Co and 30%<=Ni+Co<=55%), <=0.02% C, <=1.5% Mn, <=0.3% Si, 0.03 to 0.5% Zr, and the balance substantially Fe with impurities, and in which Zr compds. of >=0.5 μm longest size are contained by 10,000 to 500000 pieces per mm<2> of the cross section perallel to the rolling direction and the thickness direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe-Ni alloy thin plate having excellent press punching workability and suitable for use as a material for electronic parts such as lead frames.

[0002]

2. Description of the Related Art Fe-Ni alloys having low thermal expansion characteristics and excellent workability and corrosion resistance are widely used as materials for electronic components. For example, Fe-42Ni (42 alloy), Fe-29Ni-
17Co (Kovar), and in particular, Fe-36Ni (Invar), Fe-31
An Fe-Ni-based alloy such as Ni-5Co (Super Invar) is used.

[0003] When the above-mentioned Fe-Ni alloy is applied to electronic parts, Fe-Ni alloys for electronic parts are used.
The system alloy is subjected to fine processing by, for example, press punching or photo-etching.For example, in the case of a lead frame, the finer processing shape and higher precision associated with the higher integration of semiconductor devices are more strongly required. I have.

[0004]

When such a fine press punching process is performed on an Fe—Ni alloy, burrs or drooling are generated due to poor rupture properties of the material. Therefore, when the thickness is reduced, it is difficult to maintain the processing accuracy in press punching. For this reason, F
For e-Ni-based alloy thin plates, there is a strong demand for materials that are more excellent in press punching accuracy than conventional materials.

[0005] In response to such demands, many proposals have been made on the improvement of press punching workability of Fe-Ni alloy thin plates.

[0006] To improve the press punching property of Fe-Ni alloys, a proposal is made to disperse and distribute non-metallic inclusions such as oxides, carbides, nitrides and sulfides (Japanese Patent Publication No. 64-1109).
8), a proposal to disperse sulfide by containing S (Japanese Patent Application Laid-Open No. 60-255954), and a proposal to add Nb to mainly contain carbide and nitride-based precipitates (Japanese Patent Application Laid-Open No. 9-2).
No. 63891). However, sulfides and oxides cause surface defects and poor plating, and are not always preferable for use as electronic component materials. In addition, since carbides and nitrides are very hard, abrasion and breakage of the die during press punching are increased.

SUMMARY OF THE INVENTION In view of the above, the present invention provides an Fe-Ni alloy thin plate for electronic parts having good press punching properties without impairing plating properties, low thermal expansion properties, and other required properties. With the goal.

[0008]

First, the present inventor investigated various factors affecting the press punching workability of a material. As a result, it was found that inclusions and precipitates contained in the base material became a starting point of crack generation and propagation during shearing. Therefore, a material containing a large amount of such inclusions and precipitates has a large number of cracks during the shearing process, so that a break occurs before the plastic deformation of the material becomes large, and it is possible to suppress burrs and dripping, which is favorable. It was found that excellent press punching property was obtained.

[0009] However, Al ₂ O ₃ and non-metallic inclusion such as MnS as described above are less cause a large amount the inclusion surface defects and defective plating, not preferable as materials for electronic components.

[0010] The present inventors have investigated the morphology of various inclusions, precipitates and crystallization. As a result, Fe-N
It has been found that a Zr compound that can be precipitated or crystallized from a material obtained by adding Zr to an i-alloy takes an optimal shape in both shape and size to enhance the breakability of the material. In addition, it was confirmed that the Zr compound hardly impaired other properties required as electronic component materials, such as plating properties and low thermal expansion properties. That is, the inventor has found that by including a Zr compound, the effect of significantly improving press punching workability without impairing other properties has been achieved, and the present invention has been achieved.

Specifically, the present invention relates to a method for preparing Ni:
30-55% (or Ni: 27-52%, Co22%
Below, 30% ≦ Co + Ni ≦ 55%), C: 0.02
%, Mn: 1.5% or less, Si: 0.3% or less, Z
r: 0.03 to 0.5%, with the balance being substantially Fe, excluding impurities, and a Zr compound having a longest diameter of 0.5 μm or more and a square of 1 square section parallel to the rolling direction and the thickness direction. It is a Fe-Ni-based alloy thin plate for an electronic component, which contains 10,000 to 500,000 pieces per millimeter.

The Zr compound in the present invention means a compound having a composition determined by X-ray analysis or the like of compound particles, wherein Zr is 20% or more by weight%. Specifically, it is mainly composed of a compound of Zr and Ni, Fe, Si or the like,
Carbides, nitrides, carbonitrides, oxides and sulfides which cause mold wear and surface defects when contained in large amounts are not included in the Zr compound of the present invention. However, carbides, nitrides, carbonitrides, oxides and sulfides are in a range that has little effect on mold wear and surface defects, that is, up to about 2% of the total number of compound particles having a longest diameter of 0.5 μm or more. It may be contained up to a diameter of about 5 μm. The Zr compound of the present invention may be any of a crystallized substance generated by controlling cooling conditions during ingot melting and a precipitate generated by a precipitation heat treatment after hot working or before or during a cold working step. Also refers to. Adjustment of the number and size of the Zr compound is achieved by controlling these manufacturing conditions. For example, in the cooling from the molten state, by controlling the cooling conditions such that the average cooling rate from the start of solidification to the completion of solidification until the temperature is reduced to 1100 ° C. becomes 4 ° C./or more, the uniformity of the crystallized product is obtained. Dispersion occurs, and a material containing the number of Zr compounds specified in the present invention is obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The greatest feature of the present invention is that a tissue contains a Zr compound. The Zr compound contained in the material of the present invention is assumed to have a Vickers hardness of 600 HV or less from the form and the hardening amount of the material due to precipitation.
Since it is not as hard as carbides and nitrides of 000 HV or more, wear of the press die is small. Further, unlike oxides and sulfides, plating properties are unlikely to deteriorate. In addition, low thermal expansion characteristics and bending workability hardly deteriorate. And
Since the particle size and distribution of the particles are uniform, when subjected to press punching, the particles serve as a starting point of fracture, resulting in an extremely smooth fracture surface with little burr.

The reasons for limiting the numerical values of the present invention will be described below. Z
When the longest diameter of the r compound is less than 0.5 μm, the effect of improving press punching workability is small. The reason why the size of the Zr compound is indicated by the longest diameter in the present invention is that the Zr compound usually has a linear or plate-like shape, and when observed in a cross section, the size can be easily represented. is there. The longest diameter in the present invention refers to the length of the diameter of a circumcircle of a precipitate or a crystallized substance observed in a cross section parallel to the rolling direction and the thickness direction. Small particles having a longest diameter of less than 0.5 μm are unlikely to appear on the cross section at the time of shearing, so that they are less likely to be a source of stress concentration at the time of press punching, and are therefore less likely to be starting points of fracture. For this reason, the longest diameter of the Zr compound is 0.5 μm.
Those having m or more are effective.

Further, the Zr having a longest diameter of 0.5 μm or more is used.
It is necessary that the content of the compound is set so that the number per unit sectional area is within an appropriate range. If the number of particles of the compound is less than 10,000, the starting point of fracture during press punching is small, so that suppression of burrs becomes insufficient and good fine workability cannot be obtained. If the number exceeds 500,000, the plating property deteriorates. Specifically, it is necessary to contain 10,000 to 500,000 Zr compounds per square millimeter on a cross section parallel to the rolling direction and the thickness direction of the thin plate. The cross section to be observed was set to be a cross section parallel to the rolling direction and the thickness direction of the thin plate. The number of Zr compounds appearing in the cross section in this direction was the smallest, that is, if the above number was satisfied in this direction, all This is because good fine workability can be guaranteed in the cross section in the direction of.

Zr is indispensable for containing a Zr compound having the above-mentioned effect in the Fe—Ni alloy and is the most important element in the present invention. The content of Zr is
If the content is less than 0.03%, the content of the Zr compound becomes insufficient, so that the effect of improving the press punching property is small. 0.5%
If it exceeds 300, surface oxidation is likely to occur, so that the plating property is degraded and becomes unsuitable as an electronic component material. For this reason, Z
The content of r is regulated to 0.03 to 0.5%. A more desirable range is 0.1 to 0.35%.

When the content of C exceeds 0.02%, the particle size is 5 μm.
A large amount of large Zr carbides exceeding the above range inhibits the formation of the Zr compound in the present invention, and increases the wear of the die during press punching. Therefore, C is 0.0
It is regulated to 2% or less. It is more desirable that the content be 0.01% or less. By controlling the amount of carbon, the generation of carbides can be almost eliminated, and even if a part of them is generated, the particle size is as small as less than 5 μm, and the number of carbides with a particle size of 0.5 μm or more is as small as 500 or less per square millimeter. Therefore, there is almost no deterioration of the mold life.

Although Si is used as a deoxidizing agent, when Zr is added, if it exceeds 0.3%, it is concentrated on the surface to form an oxidized layer and deteriorate the plating property. %
It is specified below. More preferably, Si is 0.1% or less.

That is, a Zr compound is contained, and C, S
By controlling the amount of i, etc., it is possible to achieve an improvement in press punching workability without substantially deteriorating any of the surface properties, plating properties, low thermal expansion characteristics, and press die life.

Mn is used as a deoxidizing agent.
Exceeds 1.5%, the coefficient of thermal expansion is increased and the plating property is deteriorated. Mn is 0.5%
The following is more desirable.

The content of Ni adjusts the coefficient of thermal expansion of an electronic component manufactured using the material, and minimizes the coefficient of thermal expansion near 36% of the electronic component. However, if it is less than 30% or more than 55%, the coefficient of thermal expansion becomes too large, making it unsuitable as an electronic component material. Therefore, the content of Ni is specified to be 30 to 55%.

Although Co is not essential in the present invention, its coefficient of thermal expansion is minimized by substituting about 17% or about 5% thereof with Ni, so that it is effective especially when low thermal expansion is required. . However, if it exceeds 22%, the coefficient of thermal expansion becomes too large, which makes it unsuitable as a material for electronic parts. Therefore, when Co is contained, its content is specified to be 22% or less. When Co is contained, Ni can be partially replaced with Co from the viewpoint of the coefficient of thermal expansion, so the Ni content is specified to be 27 to 52%. Also, since the coefficient of thermal expansion is determined by the total content of Co and Ni, Co and N
The content of i is defined as 30% ≦ Co + Ni ≦ 55%.

In addition, S, O, and N form sulfides, oxides, and nitrides, respectively, and deteriorate the plating property or the life of the press die.

According to the above-described method, it is possible to obtain an Fe—Ni-based alloy sheet having extremely excellent press punching workability without impairing other characteristics.

[0025]

The present invention will be described below with reference to examples. Table 1
Was melted and cast in a vacuum high-frequency induction furnace and then forged and hot-rolled to a thickness of 4 mm, and the surface was scale-removed to a thickness of 3.5 mm. Further, cold rolling and soft annealing were repeated, and a part of the sample was subjected to a solution treatment and an aging treatment to finally obtain a sheet material having a thickness of 0.2 mm.

[0026]

[Table 1]

The particle size and density of the Zr compound contained in these Fe—Ni alloy thin plates were measured by the following methods. That is, the material of the present invention and the comparative material were distinguished by observing 30 visual fields with an electron microscope having a magnification of 5000 times and converting the number of confirmed Zr compounds having a longest diameter of 0.5 μm or more per square millimeter. .

Table 2 shows, in addition to the number of Zr compounds having a predetermined size, items for evaluating the effect of the present invention, a particle diameter of 5 μm.
m, the presence or absence of carbides, the presence or absence of surface defects, the plating properties, and the burr height during press punching.

[0029]

[Table 2]

The presence or absence of carbides having a size of 5 μm or more was determined by observing 30 visual fields with an electron microscope with a magnification of 5000 times in the same manner as the number of Zr compounds, and the presence of one or more carbides was indicated. The presence or absence of surface defects was determined by observing the front and back surfaces of the plate material by 5 cm square using an optical microscope, and showing no defects without any defects. Plating properties: After degreasing and acid treatment, apply 0.5 μm thick Cu strike plating, then apply 3 μm thick Ag plating, and then heat at 450 ° C. for 5 minutes in air to prevent plating swelling The product was evaluated as ○, and the product with swelling was evaluated as ×.
Burrs at the time of press punching, the clearance of the mold 1
The height of the burr was measured at a portion where a circular hole having a diameter of 1 mm was punched by setting to 0 μm.

In Table 1, symbols (A to G) are alloys of the present invention, and (H to N) are comparative alloys. In the table,
(A to C) are obtained by adding a Zr compound to Invar, Kovar, and 42 alloy, respectively. (CG)
In addition, (K) and (L) are obtained by changing the content of Zr in the 42 alloy. (H, I, J) are commonly used Invar, Kovar, and 42 alloys and do not contain a Zr compound. The comparative materials (H, I, J) do not contain Zr or contain a small amount of Zr, so that the particle size is not larger than 0.1%.
Does not contain a Zr compound of 5 μm or more.

In the table, Zr having a particle size of 0.5 μm or more
Each of the materials (A to G) of the present invention containing a compound has extremely small burrs at the time of press punching as compared with the comparative materials (H, I, J) not containing the compound. For example, the height of the burr of (A) containing a predetermined amount of the Zr compound is less than half that of the usual invar (H). (B ', D',
F ′) is obtained by subjecting (B, D, F) to a solution treatment and a precipitation treatment, respectively. In each case, the amount of the Zr compound having a predetermined size becomes extremely large, and burrs are further improved. (K) does not contain a predetermined amount of a Zr compound because the content of Zr is lower than the content of the present invention. For this reason,
Burr improvement is insufficient. Conversely, in (L), since the content of Zr is larger than that specified in the present invention, the plating property is deteriorated. (M) has poorer plating properties because the content of Si is higher than the specification of the present invention. In (N), since C is higher than the specification of the present invention, carbide having a diameter of 5 μm or more is generated, and the life of the press die is inevitably deteriorated.

Since all of the materials of the present invention show good surface properties, plating properties and low thermal expansion properties equivalent to those of conventional materials, the basic properties can be improved by adding a Zr compound and controlling C and Si. It can be seen that the press punching property can be improved without any loss.

[0034]

As described above, the Fe—Ni-based alloy thin plate for electronic parts of the present invention can maintain all of the surface properties, plating properties, low thermal expansion properties, and mold life while maintaining the properties. Excellent press punching workability can be provided. Therefore, the Fe—Ni-based alloy thin plate for electronic components of the present invention can cope with finer and more precise processing of electronic component materials such as lead frames, and has an extremely large industrial effect.

Claims (2)

[Claims] 1. Ni: 30 to 55% by weight, C:
0.02% or less, Mn: 1.5% or less, Si: 0.3%
Hereinafter, a Zr compound having a composition of Zr: 0.03 to 0.5%, and the balance being substantially Fe excluding impurities, and a cross section parallel to the rolling direction and the thickness direction of a Zr compound having a longest diameter of 0.5 μm or more. 10,000 to 500,000 per square millimeter
Fe-Ni-based alloy thin sheets for electronic components, characterized in that they are contained. 2. Ni: 27 to 52% by weight, C:
o: 22% or less, C: 0.02% or less, Mn: 1.5
% Or less, Si: 0.3% or less, Zr: 0.03 to 0.5
%, And the balance is substantially Fe except for impurities, and the content of Co and Ni is 30% ≦ Co + Ni ≦ 55%
Characterized in that the Fe-Ni-based alloy for electronic components contains 10,000 to 500,000 Zr compounds having a longest diameter of 0.5 μm or more per square millimeter perpendicular to the rolling direction and the thickness direction. Alloy sheet.