JPH05214491A - Fe-ni alloy excellent in plating suitability and its production - Google Patents

Abstract

PURPOSE:To produce a sheet for IC lead frame excellent in Ag plating suitabil ity and hot workability by regulating the Si segregation rate at the surface to a specific value at the time of forming a slab of Fe-Ni alloy having a specific composition into sheet-like state by means of rolling. CONSTITUTION:At the time of applying, in succession, slabbing, hot rolling, cold rolling, recrystallization annealing, temper rolling, and stress relief annealing to a cast ingot or continuously cast slab of an Fe-Ni alloy having a composition which consists of, by weight, 38-52% Ni, <0.0050% C, <0.01% Al, <0.0020% N, <0.0020% S, <0.0040% O, <1.0ppm H, <0.0040% P, 0.01-0.10% Si, 0.0002-0.0020% Ca, 0.0003-0.0020% Mg, and the balance Fe or further contains 5-18% Co and where the value of [Ca]+[Mg]/2 is regulated to 0.0005-0.0025% and also equation I and inequality II are satisfied and forming it into a sheet material, heating is done while regulating the holding time(t) at 1150-1300 deg.C (T deg.C) in the cases of >=35% and 20-70% reductions in area in the slabbing stage to values represented by inequalities IV, V and the surface Si segregation rate represented by expression III just before etching, etc., is regulated to <=10%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to Fe- which has excellent plating properties.
Suitable for Ni-based alloys, especially for lead frame materials used with Ag plating, and also excellent in solderability, and
The present invention relates to the alloy and the manufacturing method thereof in which the yield during manufacturing is also improved.

[0002]

2. Description of the Related Art As a material for an IC lead frame, 42% of Ni is contained and the balance is made of iron because of the matching coefficient of thermal expansion with semiconductor elements, glass and ceramics.
Fe-Ni alloys such as the two alloys are widely used. In recent years, Fe-28%, which is intended for high strength,
Alloys such as Ni-16.5% Co and Fe-29% Ni-6% Co are also beginning to be used. Further, as a method for producing an IC lead frame material from such an Fe-Ni alloy, a thin plate is obtained by subjecting an alloy ingot by continuous casting or ingot making to slab rolling, hot rolling, cold rolling, or the like. It is common practice to slitter the thin plate.

Further, in order to process the material thus manufactured into a lead frame, it is processed into a lead frame shape by punching or photo-etching, and then its surface is subjected to Ag plating. Bonding, wire bonding, packaging, and tin plating on the legs are commonly performed. Further, when the lead frame is attached to the substrate, it is soldered. At this time, it is strongly desired that the Fe-Ni alloy used for the IC lead frame has excellent plating properties, particularly Ag plating properties and soldering properties.

However, this alloy has poor adhesion to Ag plating, and for example, "blister" occurs in the Ag plating layer or the plating layer peels off due to heating during wire bonding to the lead frame in the IC assembly process. Problem occurs. Therefore, conventionally, Ni or Cu strike plating (short-time high current density plating) is used for pretreatment of Ag plating.
Is usually applied to the material surface.

Further, the solderability is deteriorated due to the whiskers, and needle-like fine crystals called "whiskers" are apt to grow abnormally in the tin plating applied in the preceding step, and the tin-plated leads, for example. The wetting time between the frame and the solder becomes long, resulting in a problem that the wetted area of the solder does not satisfy the required performance.

In order to improve the Ag plating property, in order to improve the Ag plating property, a small amount of Al and Ca is added in combination to significantly reduce non-metallic inclusions and to finely disperse them in the alloy to form a surface. The one in which flaws are prevented and the plating property is improved is disclosed in JP-A-62-207845. Further, in JP-A-3-166340, Co0.5-22%, Ni2
Fe-Ni system containing 2 to 32.5%, plating property,
We are trying to achieve solderability by reducing the amount of Mn and Si.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the disclosed technology of 207845, the adhesion of plating is improved when Ag plating of 3 μm thickness is applied without Ni strike plating. However, due to the recent demand for cost reduction, there is a tendency for the thickness of Ag plating to become thinner than the above, and a technique for ensuring the Ag plating property accompanying such thinning has not yet been known.

Further, according to the composite addition of Al and Ca, which is characteristic of the above-mentioned technique, a non-uniform oxide film is formed by the heat treatment performed in the manufacturing process of the lead frame material,
Due to the presence of this oxide film, whiskers frequently occurred in the tin plating subsequently applied, resulting in a marked deterioration in solderability. Further, due to the combined addition of Al and Ca, the hot workability deteriorates, and during the manufacturing process, the occurrence of flaws when the alloy lump is slab-rolled into a slab is remarkable, and the yield during manufacturing is low. It had the drawback.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 3-166340, in the Ag plating, the improvement of the plating adhesion in the case of the Ag plating having the thickness of 3 μm is achieved. However, the recent cost reduction is desired. Thin plating (Ag with a thickness of less than 3 μm
There is also a tendency for plating), and the improvement of Ag plating property due to such thinning has not been achieved. Furthermore, the improvement in solderability seen with this technique is only in terms of the weather resistance of the solder, and the wettability of the solder has not been improved.
In addition, this technique has a drawback in that a large amount of flaws are produced when the alloy ingot is slab-rolled into a slab during the manufacturing process, and the yield during manufacturing is low.

[0010] As described above, no technique has been found yet for the conventional technique alone, which achieves both the Ag plating property and the soldering property when aiming for thinner plating, and also improves the yield during manufacturing. Therefore, a material that satisfies both of these characteristics has been earnestly desired.

[0011]

In view of such conventional problems, the inventors of the present invention have excellent Ag plating properties and solderability in lead frame Fe-Ni alloys, and also improve the production yield. As a result of repeated research, as a result, in order to improve the Ag plating property (improvement of Ag plating adhesion), (1) H, S, P,
It is effective to reduce the amounts of O and Al, (2) optimize the addition of Si and optimize the Si distribution.

Further, in order to improve solderability (suppression of whisker generation during tin plating), (1) reduction of H, S and O contents, (2) addition of an appropriate amount of Si and optimization of Si distribution, 3) In order to improve the hot workability of the alloy as much as possible, suppress fine internal cracks during slabbing, and prevent the formation of microvoites on the lead end faces, C, N, S, O, It is effective to regulate the total amount of P and to add a trace amount of Mg and Ca.

Further, in order to reduce the occurrence of surface defects during slabbing (improve the yield during manufacturing) and to secure the required Ag plating property and solderability, (1) C, N,
It was found that reducing the amounts of S, O and P and (2) adding trace amounts of Mg and Ca are effective. Further, as a means for optimizing the distribution of Si, heating conditions (temperature,
It was found that the optimization of time) and processing conditions (cross-section reduction rate, number of heats) is effective, and the present invention has been completed, and is as follows.

(1) Ni: 38 to 52 wt%, C: 0.0050 wt%
Below, Al: 0.010wt% or less, N: 0.0020wt% or less, S: 0.
0020 wt% or less, O: 0.0040 wt% or less, H: 1.0 ppm or less,
P: 0.0040 wt% or less, Si: 0.01 to 0.10 wt%, Ca:
0.0002 to 0.0020wt%, Mg: 0.0003 to 0.0020wt%, [Ca] ＋ [Mg] / 2: 0.0005 to 0.0025wt%, and [C] / 10 ＋ [N] / 10 ＋ [S] ＋ [O ] / 5 + [P] / 2: 0.0045wt%, ([Ca] + [Mg] / 2) / ([S] + [O] / 5) ≧ 1 is satisfied, and the balance of inevitable impurities and Fe The component segregation rate of Si on the alloy plate surface immediately before the etching of the alloy steel strip or just before the punching of the alloy steel strip, that is, [| component concentration in the segregation region-average component concentration | / average component concentration] × 100 …… (I) is less than 10%, which is excellent in plating property.
Fe-Ni alloy.

(2) Ni: 27-30 wt%, C: 0.0050 wt%
Below, Co: 5-18%, Al: 0.010wt% or less, N: 0.0
020wt% or less, S: 0.0020wt% or less, O: 0.0040wt% or less, H: 1.0ppm or less, P: 0.0040wt% or less, Si:
0.01 to 0.10 wt%, Ca: 0.0002 to 0.0020 wt%, Mg:
0.00003 to 0.0020wt%, [Ca] + [Mg] / 2: 0.0005 to 0.0025wt% and [C] / 10 + [N] / 10 + [S] + [O] / 5 + [P] / 2: 0.0045wt%, satisfying the relationship of ([Ca] + [Mg] / 2) / ([S] + [O] / 5) ≧ 1, consisting of the balance of inevitable impurities and Fe composition, and its alloy The component segregation ratio of Si on the surface of the alloy plate immediately before the etching of the steel strip or immediately before the punching, that is, [| component concentration in the segregation region-average component concentration | / average component concentration] × 100 (I) is 10 % Or less, excellent plating property
Fe-Ni alloy.

(3) In producing an alloy having the composition according to claim 1 by an ingot making method or a continuous casting method, a steel ingot made by the ingot making method or a slab made by the continuous casting method is hereafter
Slump rolling-Scratch removal-Hot rolling-Descaling / Scratch removal-1
One time or two or more times of cold rolling (in the case of two or more times cold rolling, recrystallization annealing is performed in the middle) -recrystallization annealing-temper rolling-strain relief annealing. In obtaining the alloy thin plate, the H ₂ S concentration in the heating atmosphere in the heating furnace in the slab rolling process is 100 ppm or less,
The heating temperature is set to 1150 to 1300 ° C, and the holding time t (hr) after reaching the heating temperature is 7.71-5.33 × 10 ^-3 T ≤ log t ≤ 8.00-5.33 × depending on the heating temperature T (° C). 10 ^-3 T ......
Formula (II) is adopted, and the cross-sectional reduction rate in slab rolling is set to 35% or more, and the slab component segregation rate on the surface of the alloy sheet just before the above etching or before press punching is performed by gradually cooling after slab rolling. (Formula (I)) is set to 10% or less, a method for producing an Fe-Ni alloy having excellent plating properties.

(4) In producing an alloy having the composition according to claim 1 by an ingot making method or a continuous casting method, a steel ingot made by the ingot making method or a slab made by the continuous casting method is hereafter
Slump rolling-Scratch removal-Hot rolling-Descaling / Scratch removal-1
Immediately before etching or before press punching in the process of single or two or more cold rollings (in the case of two or more cold rollings, recrystallization annealing is performed in the middle) -recrystallization annealing-temper rolling-strain relief annealing In obtaining the alloy thin plate of No. 1, the concentration of H ₂ S in the heating atmosphere in the heating furnace in the slab rolling process is 100 ppm or less, the heating temperature is 1150 to 1300 ° C., and the holding time t after the heating temperature is reached is t. (Hr) according to the heating temperature T (℃) 7.40-5.33 × 10 ^-3 T ≤log t ≤7.71-5.33 × 10 ^-3 T ......
(III), primary slabbing is performed at a cross-sectional area reduction rate of 20 to 70%, and then the heating temperature is 1150 to 13 in the heating atmosphere.
Immediately before etching or press punching by heating at 00 ° C. within the range of the above formula (III), and then performing secondary slabbing at a cross-sectional area reduction rate of 20 to 70% and gradually cooling after slabbing. A method for producing an Fe-Ni-based alloy having excellent plating properties, characterized in that the segregation rate of Si component (formula (I)) on the surface of the previous alloy sheet is set to 10% or less.

(5) In producing an alloy having the composition according to claim 2 by an ingot making method or a continuous casting method, a steel ingot made by the ingot making method or a slab made by the continuous casting method is hereafter
Slump rolling-Scratch removal-Hot rolling-Descaling / Scratch removal-1
One time or two or more times of cold rolling (in the case of two or more times cold rolling, recrystallization annealing is performed in the middle) -recrystallization annealing-temper rolling-strain relief annealing. In obtaining the alloy thin plate, the H ₂ S concentration in the heating atmosphere in the heating furnace in the slab rolling process is 100 ppm or less,
The heating temperature is set to 1150 to 1300 ° C., and the holding time t (hr) after reaching the heating temperature is 7.71-5.33 × 10 ⁻³ T ≦ log t ≦ 8.00-5.33 × depending on the heating temperature T (° C.). 10 ^-3 T ......
Formula (II) is adopted, and the cross-sectional reduction rate in slab rolling is set to 35% or more, and the slab component segregation rate on the surface of the alloy sheet just before the above etching or before press punching is performed by gradually cooling after slab rolling. (Formula (I)) is set to 10% or less, a method for producing an Fe-Ni alloy having excellent plating properties.

(6) In producing an alloy having the composition according to claim 2 by an ingot making method or a continuous casting method, a steel ingot made by the ingot making method or a slab made by the continuous casting method is hereafter
Slump rolling-Scratch removal-Hot rolling-Descaling / Scratch removal-1
One time or two or more times of cold rolling (in the case of two or more times cold rolling, recrystallization annealing is performed in the middle) -recrystallization annealing-temper rolling-strain relief annealing. In obtaining the alloy thin plate, the H ₂ S concentration in the heating atmosphere in the heating furnace in the slab rolling process is 100 ppm or less,
The heating temperature is set to 1150 to 1300 ° C, and the holding time t (hr) after reaching the heating temperature is 7.40-0.33 × 10 ^-3 T ≤ log t ≤ 7.71-5.33 × depending on the heating temperature T (° C). 10 ^-3 T ......
(III), primary slabbing is performed at a cross-sectional area reduction rate of 20 to 70%, and then the heating temperature is 1150 to 13 in the heating atmosphere.
Immediately before etching or press punching by heating at 00 ° C. within the range of the formula (III), and then performing secondary slabbing at a cross-sectional area reduction rate of 20 to 70%, and gradually cooling after slabbing. A method for producing an Fe-Ni-based alloy having excellent plating properties, characterized in that the segregation rate of Si component (formula (I)) on the surface of the previous alloy sheet is set to 10% or less.

[0020]

The present invention as described above will be described. First, the reason for limiting the chemical composition of the alloy of the present invention will be described in terms of wt% (hereinafter simply referred to as%).

Ni is a basic component of this alloy, and Ni is 38
If it is less than 50% or more than 52%, the thermal expansion coefficient of the alloy becomes too large, and the compatibility with the semiconductor element, glass, ceramics and the like cannot be maintained. Therefore, the range of Ni is set to 38 to 52%.

Co is an element that is added as necessary when the compatibility with semiconductor elements, glass, ceramics and the like is further enhanced. If Co is less than 5% or more than 18%,
Since this effect cannot be obtained, the range of Co is set to 5 to 18%. When Co is added 5 to 18%, Ni is 27%
If it is less than 30% or more than 30%, the thermal expansion property is deteriorated. Therefore, when Co is contained 5 to 18%, Ni
Was set to 27 to 30%.

When the content of C is large, the hot workability is deteriorated, the surface defects are significantly generated during the slabbing, and the synergistic effect with N, S, O and P described later causes the slabbing. Fine cracks are generated inside the alloy and deteriorate the solderability.
That is, if C exceeds 0.0050%, the improvement in hot workability intended in the present invention cannot be achieved, so 0.0050% was made the upper limit.

When the content of N is large, a nitride precipitates on the grain boundaries, the hot workability is deteriorated, and the surface defects are significantly generated during the slabbing. Further, C, S, O, which will be described later, Synergistic action with P causes fine cracks to occur inside the alloy during slabbing and deteriorates solderability. If this N exceeds 0.0020%, the improvement in hot workability intended by the present invention cannot be achieved, so 0.0020% was made the upper limit.

In the following, the improvement of hot workability intended in the present invention is defined as reducing the occurrence of surface flaws during slabbing and preventing the generation of fine cracks inside the alloy.

S is an element that segregates at the austenite grain boundaries in the alloy, embrittles the grain boundaries, and significantly deteriorates hot workability. Also, if the amount of S is large, the amount of inclusions in the alloy increases, and Ag plating properties and soldering properties deteriorate. The amount of S for improving the hot workability intended in the present invention is 0.0020% or less under the proper addition of Mg and Ca described later. Also, the above Ag
The amount of S for improving the plating property and the soldering property is also 0.0020% or less. A more preferable amount of S for improving the plating properties is 0.0010% or less.

O is an element that precipitates as a low melting point oxide at the austenite grain boundaries in the alloy and significantly deteriorates hot workability. Also, if the amount of O is large, the amount of inclusions in the alloy increases, and Ag plating properties and soldering properties deteriorate. The amount of O for improving the hot workability intended in the present invention is Mg, which will be described later,
It is 0.0040% or less under the proper addition of Ca. Also,
The amount of O for improving Ag plating property and solderability is also 0.0
It is 040% or less, more preferably 0.0025% or less.

P is an element that segregates at the austenite grain boundaries in the alloy, embrittles the grain boundaries, and deteriorates hot workability. Further, when the amount of P is large, P and surface segregation occur during the heat treatment of the alloy steel strip, which deteriorates the Ag plating property. The amount of P for improving the hot workability intended in the present invention is 0.0040.
% Or less. Also, the amount of P for improving the Ag plating property is 0.
It is 0040% or less, more preferably 0.0010% or less.

Si is one of the important alloying elements for the purpose of deoxidizing in the present alloy, but from the viewpoint of Ag plating property and soldering property, its amount and distribution must be controlled. But also. If the amount of Si is less than 0.01%, the amount of O does not fall below 0.0040% specified in the present invention.
On the other hand, if the content exceeds 0.10%, the
Since a non-uniform oxide film is formed and Ag plating property and soldering property are deteriorated, the lower limit of Si is 0.01% and the upper limit of Si is 0.10%.

Even when the amount of Si is within this range, if the variation of Si component on the alloy surface is large, there is a region where the Ag plating property and the soldering property are locally deteriorated, and as a result, these plating properties are deteriorated. Such component variations must be controlled as problems arise. Therefore, in the present invention, in addition to the regulation of the above Si amount, the component segregation ratio of Si on the alloy plate surface immediately before etching or immediately before press punching, that is, [| component concentration in the segregation region-average component concentration | / average component concentration] By setting × 100 to 10% or less, Ag due to the above component fluctuation
Solves local deterioration of plating and soldering.

Further, even if the segregation ratio of Si is 10% or less, if it is less than 0.01% in the minimum concentration portion, the properties of the oxide film formed during the heat treatment of the alloy steel strip become non-uniform,
As a result, there is a problem with the Ag plating property, while the maximum density is 0.
If it exceeds 10%, the Ag plating property and the solder property are deteriorated, so control is performed so as not to cause this.

When the amount of Al is large, a strong oxide film of Al is generated during the heat treatment of the alloy steel strip, particularly the Ag plating property is deteriorated, and the low melting point oxide is contained in the alloy in the presence of Ca. And the hot workability deteriorates. The amount of Al for improving Ag plating property and hot workability intended in the present invention is 0.010.
% Or less, more preferably 0.0005% or less.

H is an element that has a significantly great influence on the plating property of the present alloy. That is, H is inevitably mixed during melting in this alloy, and its amount is 1.
It exceeded 0 ppm, and in some cases about 4 to 7 ppm remained. This gas is released during the heating of the die bonding after spot plating of Ag in the IC manufacturing process, moves to the interface between the plating layer and the base alloy (lead frame material), and causes plating failure called "blister". This phenomenon
When the thickness of the Ag plating layer is relatively thick, which is about 3 μm in the related art, there was no problem in terms of the strength of the plating layer. However, due to the recent trend of thinning Ag, 2 μm
Thinner plating thicknesses are becoming common, and the strength of the Ag plating layer becomes smaller than the gas pressure of H at such a thin Ag plating thickness, and the problem of "blister" mentioned above becomes apparent. It was Also, the above-mentioned conventional level H
Even when soldering an alloy containing Al, there is a problem that the wettability of the solder is inferior. The adverse effect on the plating property due to the presence of such a trace amount of H is particularly recognized in the present alloy.

As described above, when H exceeds 1.0 ppm, the present alloy cannot obtain the plating property intended by the present invention, so 1.0 ppm was made the upper limit. In addition, in order to obtain the amount of H specified in the present invention, it is necessary to optimize the vacuum degassing method during melting. That is, in order to reduce the apparent hydrogen pressure, in the alloy intended in the present invention, a high vacuum degree of a pressure equal to or lower than 0.1 torr can be achieved, and the bottom-blown diluted Ar gas amount can be increased. The method is adopted.

While ensuring the Ag plating property and the soldering property intended by the present invention, the improvement of the hot workability of the present alloy is achieved as much as possible to suppress the fine internal cracks during the slabbing rolling, and the lead end surface In order to prevent the formation of micro voids and improve the solderability, the total amount of C, N, S, O and P must be specified and M
A small amount of combined addition of g and Ca is required. Ie C / 1
When 0 + N / 10 + S + O / 5 + P / 2 exceeds 0.0045%,
Grain boundary embrittlement becomes remarkable due to the decrease in grain boundary strength due to N, S, O, P and intragranular strengthening due to C, and fine cracks occur at the triple point of austenite grain boundaries during slab rolling. Even in the subsequent hot rolling process, it remains as cracks inside the alloy without being pressure-bonded and deteriorates the solderability. Therefore, the upper limit of C / 10 + N / 10 + S + O / 5 + P / 2 is 0.00
It was set to 45%.

In order to improve the hot workability intended in the present invention, in addition to the reduction of C, N, S, O and P as described above, C
It is essential to add a proper amount of a and Mg according to the S and O amounts. That is, Ca is 0.0002 to 0.0020% and Mg is 0.000%.
3 to 0.0020%, and Ca + Mg / 2: 0.0005 to 0.
0025% and (Ca + Mg / 2) /, depending on the amount of S and O
(S + O / 5) ≧ 1 is required.

FIG. 1 shows the relationship between the Ag plating property, the solder property, the slab defect removal amount, and the Ca and Mg amounts. When Ca is less than 0.0002% and Mg is less than 0.0003%, it is not intended in the present invention. No improvement in hot workability was achieved and no improvement in solderability was obtained. On the other hand, if the content of both components exceeds 0.0020%, a strong oxide film is formed on the surface during heat treatment of the alloy steel strip, Ag plating properties and solderability are impaired.

The effect of improving the hot workability intended by the present invention is
It does not appear sufficiently with the addition of either Ca or Mg alone,
In both cases, it is necessary to add more than the lower limit specified in the present invention. That is, if Ca + Mg / 2 is less than 0.0005%, the improvement in hot workability and solderability targeted by the present invention cannot be obtained, while if Ca + Mg / 2 exceeds 0.0025%, the alloy steel is A strong oxide film is formed on the surface during heat treatment of the strip, impairing the Ag plating property and solderability. From these, Ca
+ Mg / 2 was set in the range of 0.0005% to 0.0025%.

It is considered that the improvement of the hot workability by adding Ca and Mg as described above is because S and O are fixed as stable and harmless precipitates in the solidification process. In the case of the present alloy, Ca and Mg have different temperature ranges where precipitates of S and O are formed, which is the reason why the combined addition of Ca and Mg can fix S and O more sufficiently as stable precipitates. It is presumed that

The lower limit of the total amount of Ca and Mg can be changed according to the amounts of S and O. By satisfying this requirement, the Ag plating property and the soldering property can be increased to a high level, and the present invention intends. The hot workability can be increased to a higher level. That is, FIG. 2 shows Ag plating property, solder property,
Slab flaw removal and [Ca] + [Mg] / 2, [S] + [O] / 5
The relation of (Ca + Mg / 2) / (S + O / 5) is 1
In the above case, the hot workability can be further improved, and the surface flaw removal amount can be reduced, as compared with the case where only the respective regulations of Ca and Mg contents are satisfied.

On the other hand, (Ca + Mg / 2) / (S + O / 5)
Is less than 1, even if the amounts of Ca, Mg, S, and O are within the scope of the present invention, S and O cannot be immobilized as completely stable and harmless precipitates, so basically, Although having the high hot workability intended by the present invention, (Ca +
A dramatic improvement in hot workability as in the case of Mg / 2) / (S + O / 5) ≧ 1 cannot be obtained. From the above, as a condition for further improving the hot workability intended by the present invention and achieving a high level of Ag plating property and solderability (Ca +
Mg / 2) / (S + O / 5) ≧ 1 was defined.

By the above compositional regulation, the hot workability can be improved while improving the Ag plating property and the soldering property of the Fe-Ni alloy targeted by the present invention. The atmosphere of the heating furnace in the slab rolling process, heating,
Further optimization of the above characteristics can be achieved by optimizing the processing conditions.

First, as one of the methods for further reducing the segregation of Si components, the heating temperature, holding time, and
It is the optimization of processing conditions. That is, when the steel ingot by the ingot making method or the slab by continuous casting is slab-rolled, in the case of one-heat slab in which heating and rolling are performed only once, as shown in FIG. 3, 1150 ≦ T (° C.) ≦ 1300 ・ ・ ・ (V) formula log t ≧ 7.71−5.33 × 10 ⁻³ T ・ ・ ・ ・ (VI) formula log t ≦ 8.00−5.33 × 10 ⁻³ T ・ ・ ・ ・ (VII) formula In the formula, t is a holding time (hr), T is a heating temperature (° C.), and these are simply referred to as t,
Heated under the condition of satisfying the formulas V to VII 3 of T,
By performing slab rolling at a cross-section reduction rate of 35% or more, and gradually cooling after rolling, the segregation rate of Si can be reduced to 10% or less, and the slab obtained by slab rolling is flawed The amount can be 5 mm or less.

If the lower limit of the formula (V) is not satisfied or the formula (VII) is not satisfied, the segregation ratio of Si in the final plate thickness is 10%.
It becomes super and is unsuitable. If the upper limit of the formula (V) is not satisfied or the formula (VII) is not satisfied, the flaw removal amount (per one side) of the slab after slabbing exceeds 5 mm, the hot yield is poor, and the range of the present invention is satisfied. Outside.

Further, when the steel ingot or the continuously cast slab is subjected to slab-rolling, in the case of slabbing of two heats in which heating and rolling are performed twice, the microsegregation of Si is at a lower level than in one heat. be able to. In this case, as shown in FIG. 4, 1150 ≦ T (° C.) ≦ 1300 ... (VIII) formula log t ≧ 7.40−5.33 × 10 ⁻³ T ··· (IX) formula log t ≦ 7.71−5.33 × 10 ⁻³ T ... (X) Equation (VIII) to X are heated under the conditions that satisfy the equations, and the first slabbing process is performed at a cross-section reduction rate of 20 to 70%.
It is reheated under the conditions that satisfy the above three formulas, and then, by the second slabbing, it is processed within the range of the cross-sectional reduction rate of 20 to 70%, and after the processing, it is gradually cooled to segregate Si components. 1
It can be set to 0% or less, and the amount of flaw removal of the slab obtained by the slab rolling can be set to 5 mm or less.

It should be noted that less than the lower limit of the formula (VIII), or (I
When the formula X) is not satisfied, the segregation rate of Si in the final plate thickness exceeds 10%, which is not suitable. If the upper limit of the formula (VIII) is not satisfied or the formula (X) is not satisfied, the flaw removal amount (per one side) of the slab after slabbing exceeds 5 mm, the hot yield is poor, and it is outside the range of the present invention. Is.

By controlling the H ₂ S concentration in the atmosphere of the heating furnace at the time of heating, the generation of surface defects at the time of slabbing can be made lower. That is, H ₂ S in the heating atmosphere is 100 pp
If it exceeds m, grain boundary embrittlement due to S occurs on the surface and in the vicinity thereof, and surface defects are often generated after slabbing. , Slab flaw removal amount (per side) is 5mm
Therefore, the upper limit of the H ₂ S concentration is set to 100 ppm.

Further, by gradually cooling after the slabbing rolling, the segregation rate of Si component can be made lower. That is, the method of reducing the component segregation of Si to the level intended by the present invention, in addition to the above method, segregation prevention during ingot production, rapid solidification (casting into thin slabs), specifically, during casting Electromagnetic stirring, unidirectional solidification, light pressure casting, shortening of solidification time by adopting flat steel ingot, or hot working, warm working, cold working and one or more kinds of processing each during the strip manufacturing process, It can be achieved by a combination of heat treatments.

[0049]

EXAMPLES Specific examples of the present invention are described below. (Example 1) A Fe-Ni alloy was tapped in an electric furnace and then ladle refining was performed to obtain a 7-ton ingot. For ladle refining of this product after tapping, a ladle consisting of CaO: 40% or less of MgO-CaO refractory was used, and the content of slag was wt%, and [CaO] / [SiO ₂ ] : 0.65-0.8, Al
₂ O _{3: 3%} or less, MgO: 15% or less of CaO -SiO ₂ -Al ₂ O
_{It is of the 3} type, and by treatment with this, an alloy having the chemical composition shown in the following Table 1 was obtained.

[0050]

[Table 1]

No. 1 to No. 19 obtained as described above
And after caring for No. 21 steel ingot, 12 at 1200 ℃
After heating for 1 hour, slab rolling is performed at the primary slab with a cross-sectional reduction rate of 60%, and then at 1200 ° C for 12 hours,
A slab was obtained by performing slab rolling in the next slab with a cross-sectional reduction rate of 45% and then slowly cooling. Alloy No. 20 is a 7 ton steel ingot having the same composition as sample material No. 1
A slab was prepared by heating at 1200 ° C. for 15 hours, slab rolling at a cross-section reduction rate of 78%, and slow cooling. The H ₂ S concentration in the atmosphere gas of the heating furnace is 55 ppm.

These slabs were cared for, coated with an antioxidant, heated at a heating temperature of 1100 ° C., and then hot-rolled. At this time, the total reduction rate at 1000 ° C. or higher was 82%, the total reduction rate at 850 ° C. or higher was 98%, and the coiling temperature of the hot-rolled hot-rolled coil was 55%.
It was 0-750 degreeC. The occurrence of surface defects on the slab was examined by visual observation and color check. The amount of surface flaw removal was determined by cleaning the slab surface with a solvent grinder until the surface flaw disappeared, and measuring the change in the width and thickness of the slab before and after the maintenance. Fine internal cracks in the alloy were examined by UST inspection of the alloy steel strip.

The hot-rolled coil obtained as described above is descaled, cold-rolled and annealed repeatedly, and finally temper-rolled to obtain an alloy plate having a required surface roughness of 0.15 mm. Each was obtained, and then strain relief annealing was performed to obtain an alloy plate. However, the segregation ratio of Si on the plate surface of each of these alloy plates is EP
It investigated by the mapping analyzer (area analysis) by MA.

The silver plating property is 450 ° C. after the alloy thin plate is pre-treated by degreasing → pickling and then plated with 1 μm thick Ag.
It was conducted by heating in the atmosphere for 5 minutes and then checking the presence or absence of generation of plating blisters by magnifying 50 times.

For the soldering property, a material having a thickness of 1.5 μm and plated with tin on the alloy thin plate is used, and the solder composition is Sn 60%, Pb 40%, and solder bath temperature 2 by the meniscograph method.
The sample was immersed in a solder bath under the conditions of 35 ± 5 ° C., solder bath immersion depth of 2 mm, and solder bath immersion time of 5 seconds, and evaluation was performed at solder wet time t ₂ . Further, the test material was heated at 100 ° C. in the atmosphere, and the degree of deterioration of solderability was also examined. The results are shown in Table 2 below.

[0056]

[Table 2]

That is, the sample materials Nos. 1, 2, 3, and 4 are C, N, S, O, P, Si, Ca, Mg, [Ca] + [Mg] / 2,
[C] / 10 ＋ [N] / 10 ＋ [S] ＋ [O] / 5 ＋ [P] / 2, ([Ca] ＋ [Mg]
/ 2) / ([S] + [O] / 5), the segregation ratio of Si is within the scope of the present invention, the occurrence of surface defects is small, and the Ag plating property and soldering property are excellent. The intended effect is exhibited. In particular, sample materials Nos. 1, 3, and 4 are C, N,
S, O, and P are reduced to a more preferable level, and Ag plating property and soldering property are also at excellent levels. On the other hand, each of the test materials Nos. 5 and 6 had C and N exceeding the amounts specified in the present invention, and many surface defects were generated.

The test materials Nos. 7, 8 and 9 are respectively
The contents of S, O, and P exceeded the amounts prescribed in the present invention, the occurrence of surface defects was larger than that of the present invention, and one or more types of Ag plating property and soldering property were inferior. Particularly, in the material of No. 8, Si is below the regulation of the present invention, and O exceeds the regulation of the present invention. Thus, it is understood that proper addition of Si as a deoxidizer is necessary.

Each of the test material Nos. 10 and 20 exceeds the upper limit of Si, and the segregation ratio of Si exceeds the upper limit specified in the present invention, but especially Ag plating property and soldering property are It is inferior to sample materials No. 1, 2, 3, and 4. Especially No. Material No. 11 is a component characterized by JP-A No. 62-207845, but it has a markedly poor hot workability, has a large number of surface defects, has a large amount of surface defects, and has a problem in manufacturability. I understand. In addition, 1 μm thick Ag plating property,
The solderability is slightly inferior to the invention examples (No. 1, 2, 3, 4 materials).

Each of the test materials Nos. 12, 14, and 16 had Ca, Mg, and Ca + Mg / 2 exceeding the upper limits specified in the present invention. Ag plating property and soldering property were the same as those of the present invention. It is inferior in comparison.

Further, each of the test materials Nos. 13, 15, and 17 had Ca, Mg, and [Ca] + [Mg] / 2 below the lower limit specified in the present invention, and had fine internal cracks. Occurrence was slightly observed, and the solderability was inferior to that of the examples of the present invention (Nos. 1, 2, 3, and 4 materials), many surface defects were generated, and a large amount of surface defects were removed.

Further, the sample material No. 18 is [C] / 10 + [N] / 10
This is the case where + [S] + [O] / 5 + [P] / 2 exceeds the specification of the present invention. In this case, minute internal cracks are observed, particularly remarkable deterioration in solderability is observed, and surface defects Occurrence No. 1, 2,
It is larger than that of materials 3 and 4.

Specimen No. 19 is ([Ca] + [Mg] / 2) /
Although ([S] + [O] / 5) is outside the scope of the present invention, the amount of surface flaw removal is larger than that of the test materials Nos. 1, 2, 3, and 4. In the sample material No. 21, H is outside the scope of the present invention, and the Ag plating property and the solder property are deteriorated.
In particular, the solderability is deteriorated when whiskers are generated during tin plating, and there is a good correlation between them.

As described above, also in the Fe-Ni alloy for lead frames, the effect intended by the present invention can be obtained only under the control of the segregation ratio of the components and Si specified in the present invention. Recognize. In particular, the alloy featured in the present invention has a high hot workability even when a method other than slabbing is used as a method of reducing the segregation rate of Si. It also has the advantage of high yield during the manufacturing process. For example, even when the molten steel of the present alloy is rapidly cooled and solidified to produce a thin slab, the occurrence of surface defects is extremely small and the yield is high.

(Example 2) After obtaining a steel ingot having the same composition as the test materials No. 1 and No. 3 in the above-mentioned Example 1, the slab rolling conditions as shown in Table 3 below were obtained. Then, the slab was obtained by gradually cooling after slab rolling. Later,
Under the same manufacturing conditions as in Example 1, an alloy plate having a plate thickness of 0.15 mm was obtained.

[0066]

[Table 3]

Segregation rate of Si, generation of surface flaws, amount of surface flaw removal,
Example 1 shows solderability, silver plating property, and generation of fine internal cracks.
It investigated by the method similar to. The results are shown in Table 4 below.

[0068]

[Table 4]

That is, the test materials Nos. 22, 23, 27,
Each of the No. 28 materials had the H ₂ S concentration in the heating furnace atmosphere, the heating temperature of the slabbing rolling, the heating time, and the workability within the scope of the present invention. At an excellent level.

On the other hand, sample materials No. 24, 25, 2
Each of Nos. 9, 30, 34, and 35 has a workability in one heat agglomeration that is lower than the lower limit specified in the present invention, and a heating time in one heat agglomeration is less than the lower limit of the formula (III). The heating time of the first heat in the second heat agglomeration is less than the lower limit of the formula (IV), the processing degree of the second heat in the second heat agglomeration is below the lower limit of the present invention, the second heat In the lump, the heating temperature of the first heat and the second heat is less than the lower limit specified in the present invention, and the workability of the first heat in the second heat lump is lower than the lower limit specified in the present invention. The segregation rate of Si exceeds 10%, and there is a problem in Ag plating properties and solderability.

On the other hand, each of the test materials Nos. 26, 31, and 33 has a heating time in one heat agglomeration exceeding the upper limit of the formula (III), and a second heat agglomeration in the second heat agglomeration. The heating time exceeds the upper limit of the formula (IV), the heating temperature in one heat agglomeration exceeds the upper limit of the present invention, and in both cases, surface defects are caused by the present invention example (sample No. 22, Sample No. 22, 23, 2
7 and 28), and the amount of surface flaw removal is also large. Sample material
In No. 32, the H ₂ S concentration in the heating furnace exceeds the regulation of the present invention, and the heating and processing conditions in the lumps are within the regulation of the present invention, but surface defects are extremely large.

From the above, it is understood that even if the chemical composition is within the range of the present invention, the conditions for slab rolling must be within the range of the present invention.

[0073]

According to the present invention as described above,
It is possible to provide an alloy which improves the Ag plating property of an IC lead frame as compared with the conventional one, is excellent in solderability, and further improves the yield at the time of manufacturing, and a preferable manufacturing method thereof, and its industrial value. It is an extremely large invention.

[Brief description of drawings]

[Fig.1] Ag plating property, soldering property, slab defect removal amount and Ca,
It is a chart showing the relationship of the amount of Mg.

[Fig.2] Ag plating property, solder property, slab defect removal amount [Ca] +
It is a chart showing the relation of 1/2 [Mg], [S] + 1/5 [O].

FIG. 3 is a chart summarizing the relationship between the segregation rate of Si at the final plate thickness, the slab flaw removal amount, the heating temperature, and the heating time when the cross-section reduction rate in slabbing ≧ 35%. ..

FIG. 4 is a cross sectional reduction rate of 20 to 7 in the primary lump and the secondary lump.
It is the chart which summarized and showed the segregation rate of Si in the case of 0%, the amount of slab defects, the heating temperature, and the heating holding time in the case of 0%.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 20, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

[0056]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication C22C 38/08 C22F 1/10 Z 9157-4K H01L 23/48 V 8225-4M (72) Inventor Tomoyoshi Okita 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan KK (72) Inventor Shinichi Okimoto 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Koube KK

Claims (6)

[Claims] 1. Ni: 38 to 52 wt%, C: 0.0050 wt% or less, Al: 0.010 wt% or less, N: 0.0020 wt% or less, S: 0.0020 wt% or less, O: 0.0040
wt% or less, H: 1.0 ppm or less, P: 0.0040 wt% or less, Si: 0.01
~ 0.10wt%, Ca: 0.0002-0.0020wt%, Mg: 0.0003-0.0020wt
%, [Ca] + [Mg] / 2: 0.0005 to 0.0025wt%, and [C] / 10 + [N] / 10 + [S] + [O] / 5 + [P] / 2: 0.0045wt %, ([Ca] + [Mg] / 2) / ([S] + [O] / 5) ≥ 1 is satisfied, the balance consists of unavoidable impurities and Fe component composition, and the alloy steel strip is etched. The component segregation ratio of Si on the surface of the alloy plate immediately before or immediately before punching, that is, [| component concentration in the segregation region-average component concentration | / average component concentration] x 100 (I) formula is 10% or less. Excellent plating property
Fe-Ni alloy. 2. Ni: 27 to 30 wt%, C: 0.0050 wt% or less, Co: 5 to 18%, Al: 0.010 wt% or less, N: 0.0020 wt% or less, S: 0.002
0 wt% or less, O: 0.0040 wt% or less, H: 1.0 ppm or less, P: 0.004
0 wt% or less, Si: 0.01 to 0.10 wt%, Ca: 0.0002 to 0.0020 wt%, Mg: 0.0003 to 0.0020 wt%, [Ca] + [Mg] / 2: 0.0005 to 0.0025 wt%, and [ C] / 10 ＋ [N] / 10 ＋ [S] ＋ [O] / 5 ＋ [P] / 2: 0.0045wt%, ([Ca] ＋ [Mg] / 2) / ([S] ＋ [O] / 5) ≧ 1 is satisfied, the balance consists of inevitable impurities and the composition of Fe, and the segregation rate of Si on the alloy plate surface immediately before etching of the alloy steel strip or immediately before press punching, that is, [| segregation area Component concentration−average component concentration | / average component concentration] × 100 (I) is 10% or less, excellent plating property
Fe-Ni alloy. 3. When producing an alloy having the component composition according to claim 1 by an ingot making method or a continuous casting method, a steel ingot made by the ingot making method or a slab made by the continuous casting method is thereafter subjected to slab rolling-defect removal- Hot rolling-Descaling / defect removal-Cold rolling once or twice or more (in the case of two or more cold rolling, recrystallization annealing is performed in the middle) -Recrystallization annealing-Quench rolling-
In obtaining the alloy sheet just before etching or before press punching in the strain relief annealing step, the H ₂ S concentration in the heating atmosphere in the heating furnace in the slabbing step is 100 ppm or less, and the heating temperature is 1150 to 1300 ° C. The holding time t (hr) after reaching the heating temperature is 7.71-5.33 × 10 ^-3 T ≤log t ≤8.00-5.33 × 10 ^-3 T depending on the heating temperature T (° C).
Formula (II) is adopted, and the cross-sectional reduction rate in slab rolling is set to 35% or more, and the slab component segregation rate on the surface of the alloy sheet just before the above etching or before press punching is performed by gradually cooling after slab rolling. (Formula (I)) is set to 10% or less, a method for producing an Fe-Ni alloy having excellent plating properties. 4. When producing the alloy having the composition of claim 1 by the ingot casting method or the continuous casting method, a steel ingot by the ingot casting method or a slab by the continuous casting method is subsequently subjected to slab rolling-defect removal- Hot rolling-Descaling / defect removal-Cold rolling once or twice or more (in the case of two or more cold rolling, recrystallization annealing is performed in the middle) -Recrystallization annealing-Quench rolling-
In obtaining the alloy thin plate just before etching or before press punching in the strain relief annealing step, the H ₂ S concentration in the heating atmosphere in the heating furnace in the slabbing step is 100 ppm or less, and the heating temperature is 1150 to 1300 ° C. The holding time t (hr) after reaching the heating temperature is 7.40-5.33 × 10 ^-3 T ≤ log t ≤ 7.71-5.33 × 10 ^-3 T according to the heating temperature T (° C).
(III), primary slabbing is performed at a cross-sectional area reduction rate of 20 to 70%, and then the heating temperature is 1150 to 13 in the heating atmosphere.
Immediately before etching or press punching by heating at 00 ° C. within the range of the above formula (III), and then performing secondary slabbing at a cross-sectional area reduction rate of 20 to 70% and gradually cooling after slabbing. A method for producing an Fe-Ni-based alloy having excellent plating properties, characterized in that the segregation rate of Si component (formula (I)) on the surface of the previous alloy sheet is set to 10% or less. 5. When producing an alloy having the composition as set forth in claim 2 by an ingot casting method or a continuous casting method, a steel ingot produced by the ingot making method or a slab made by the continuous casting method is thereafter subjected to slab rolling-defect removal- Hot rolling-Descaling / defect removal-Cold rolling once or twice or more (in the case of two or more cold rolling, recrystallization annealing is performed in the middle) -Recrystallization annealing-Quench rolling-
In obtaining the alloy sheet just before etching or before press punching in the strain relief annealing step, the H ₂ S concentration in the heating atmosphere in the heating furnace in the slabbing step is 100 ppm or less, and the heating temperature is 1150 to 1300 ° C. The holding time t (hr) after reaching the heating temperature is 7.71-5.33 × 10 ^-3 T ≤log t ≤8.00-5.33 × 10 ^-3 T depending on the heating temperature T (° C).
Formula (II) is adopted, and the cross-sectional reduction rate in slab rolling is set to 35% or more, and the slab component segregation rate on the surface of the alloy sheet just before the above etching or before press punching is performed by gradually cooling after slab rolling. (Formula (I)) is set to 10% or less, a method for producing an Fe-Ni alloy having excellent plating properties. 6. When producing an alloy having the component composition according to claim 2 by an ingot making method or a continuous casting method, a steel ingot made by the ingot making method or a slab made by the continuous casting method is subsequently subjected to slab rolling-defect removal- Hot rolling-Descaling / defect removal-Cold rolling once or twice or more (in the case of two or more cold rolling, recrystallization annealing is performed in the middle) -Recrystallization annealing-Quench rolling-
In obtaining the alloy sheet just before etching or before press punching in the strain relief annealing step, the H ₂ S concentration in the heating atmosphere in the heating furnace in the slabbing step is 100 ppm or less, and the heating temperature is 1150 to 1300 ° C. The holding time t (hr) after reaching the heating temperature is 7.40-5.33 × 10 ^-3 T ≤ log t ≤ 7.71-5.33 × 10 ^-3 T depending on the heating temperature T (° C).
(III), primary slabbing is performed at a cross-sectional area reduction rate of 20 to 70%, and then the heating temperature is 1150 to 13 in the heating atmosphere.
Immediately before etching or press punching by heating at 00 ° C. within the range of the formula (III), and then performing secondary slabbing at a cross-sectional area reduction rate of 20 to 70%, and gradually cooling after slabbing. A method for producing an Fe-Ni-based alloy having excellent plating properties, characterized in that the segregation rate of Si component (formula (I)) on the surface of the previous alloy sheet is set to 10% or less.