JPH04202642A - Fe-ni alloy having high strength and low thermal expansion and excellent in plating suitability, solderability, and repeated bendability and its production - Google Patents

Abstract

PURPOSE:To provide superior low thermal expansion characteristics, plating suitability, and solderability by subjecting an Fe-Ni alloy with a specific composition to plastic working and to ageing treatment under respectively specified conditions and also specifying the segregation rate of Si. CONSTITUTION:This alloy has a composition which consists of, by weight, 39-45% Ni, <=1.0% Co, 0.1-0.7% Mn, <=0.30% Si, 0.10-0.20% Al, <=0.010% P, <=0.0030% S, <=0.0040% O, <=0.0030% N, <=0.0100% C, 1.0-3.0% Ti, and the balance Fe with inevitable impurities and in which (Ni+Co) is regulated to 39-46%. An ingot of this alloy is subjected to plastic working and heat treatment, and final plastic working is done at 10-90% draft. Subsequently, ageing treatment is performed at 500-800 deg.C for 10-500min. By the above treatment, the segregation rate of Si represented by expression I at the surface of the alloy sheet just before the etching or just before the press blanking of the alloy steel strip is regulated to <=10%. This alloy has high strength and superior repeated bendability.

Description

Detailed Description of the Invention Object of the Invention (Industrial Field of Application) The present invention relates to a high-strength, low-thermal-expansion Fe-Ni alloy suitable as a lead frame material for multi-pin ICs, and a method for producing the same. The present invention relates to an alloy that has low thermal expansion characteristics equivalent to those of alloys, excellent plating and solderability, higher strength than conventional alloys, and excellent repeated bendability, and a method for producing the same.

(Prior art) As a material for IC lead frames, N
Fe--Ni alloys such as alloy 42, which contains about 42% i and the balance is iron, have been widely used in the past. However, in recent years, the development of highly integrated large-scale integrated circuits (LSI) and very large-scale integrated circuits (very large-scale integrated circuits) has become active, and with this, lead frames are also becoming more pin-counted. It's progressing. That is, in the past, the width of the inner reed was about 0.3 to 0.5 mm, or about 0.15 to 0.2 mm. If the width of the inner lead is reduced in this way, the material strength of the inner lead will be insufficient, so there is a problem that the inner lead will be easily deformed by external force during transportation or taping of the separator during the manufacturing process. . From this, Fe-Ni
Alloys are also required to be highly strengthened.

Further, in addition to the above-mentioned requirement for high strength, the materials for IC lead frames that require high reliability are also required to have good surface treatment properties. That is, in order to process the IC lead frame material into a lead frame, it is processed into a lead frame shape by punching or photo-etching, and then Au or Ag plating is applied to the surface of the material, followed by Si chip die bonding, wire bonding, etc. The packaging and legs are usually tin-plated. Furthermore, when the lead frame is attached to the board, soldering is performed. On this occasion,
Materials for IC lead frames are strongly required to have excellent plating properties, particularly Au plating properties, Ag plating properties, and solderability. However, conventional Fe-Ni alloys have poor adhesion to the above-mentioned precious metal plating, especially Ag.
Adhesion with plating has become a problem, and there have also been cases where problems have arisen with solderability. For example, during wire bonding to a lead frame in the IC assembly process, heat may cause the Au plating layer or Ag plating layer to "
Problems such as "blistering" or peeling of the plating layer may occur.Therefore, conventionally, pre-treatment for Ag plating involves applying strike plating (short-time high current density plating) of Ni or Cu to the surface of the material. It is.

In addition, the solderability is affected by the abnormal growth of needle-shaped microcrystals called "whiskers" in tin plating, which is performed in the previous process, and these whiskers cause deterioration.
For example, the wetting time between a tin-plated lead frame and solder becomes longer, resulting in a problem in that the wetted area of the solder does not meet the required performance.

In response to these conventional requests, Japanese Patent Application Laid-Open No. 2-159348
No suggestions have been made. That is, in this technology, Ni
: 30 to 50%, Co: 2.0% or less, Mn: 0.
1 to 0.8%, Si: 0.5% or less, Be: 0
．． A Fe-Ni alloy consisting of 0.5% to 2.0% balance Fe and unavoidable impurities is aged by heat treatment at a temperature range of 300 to 700°C for 5 hours or less at the same time as the final plastic working or after the final plastic working. The present invention provides a material for lead frames that has high strength through precipitation hardening and has thermal expansion characteristics (average coefficient of thermal expansion between 30° C. and 300° C.) that are equivalent to conventional alloys.

Ru.

(Problem to be solved by the invention) However, the technology disclosed in JP-A-2-159348 maintains a coefficient of thermal expansion close to that of silicon elements and sealing ceramics, and also has better hardness, tensile strength, and bendability than before. Although an alloy with excellent deformation resistance has been obtained, this technology has not achieved improvements in surface treatment properties such as Au plating properties, Ag plating properties, and solderability, which are required for IC lead frame materials. In fact, when Be, which is a feature of this disclosed technology, is added, the surface treatability of the above alloy is even worse than that of conventional Fe-Ni alloys. In addition, the strength level obtained with the technique disclosed in JP-A-2-159348 is 3 in terms of hardness (Hv).
08, the tensile strength is 111 kgf/mm2, and the current situation is that it is becoming necessary to have a strength even higher than this due to the demand for further thinning of lead frame materials. In addition, from the viewpoint of the harmfulness of Be, alloys to which Be is added have many practical problems, such as scrap disposal problems caused by press punching and contamination of the etching solution after etching.

(Means for Solving the Problems) In view of the above-mentioned conventional problems, the present invention has been developed to have higher strength than conventional alloys, which is suitable as a multi-bin IC lead frame material, and in particular, to have a low heat equivalent to conventional alloys. The present invention has been completed after repeated studies on a Fe-Ni alloy that has expansion properties, plating properties, solderability, and excellent repeated bending properties, and a method for manufacturing the same. It is like that.

(1) Ni: 39-45wt%, Ni+Co
: 39-46wt%.

Co: 1.0wt% or less, Mn: 0.1 to 0.7
wt%.

Si: 0.30wt% or less, AA: 0.10~
0.20wt%.

P: 0.010 wt% or less, S: 0.0
030wt% or less.

0: 0.0040wt% or less, N: 0.00
30wt% or less.

C: 0.0100wt% or less, Ti: 1. O
~3.0wt%.

, and the remainder consists of inevitable impurities and Fe, and the Si component segregation rate on the alloy plate surface immediately before etching or press punching of the alloy steel strip,
That is, ... (I) High strength, low thermal expansion Fe-N with excellent plating properties, solderability, repeatability and bending properties, characterized by a formula (I) of 0% or less.
i-alloy.

(2) Ni: 39-45ivt%, Ni+Co: 39
~46wt%.

Co: 1.0wt% or less, Mn: O, 1 to 0.7w
t%.

Si: 0.30wt% or less, Aβ: 0.10-0.
20wt%.

P: 0.0100wt% or less, S: 0.30
wt% or less.

0: 0.0040wt% or less, N: 0.00
30wt% or less.

C: 0.0100wt% or less, Ti: 0.5-2.0
wt%.

Nb: Contains 0.05-2.00wt%, 1, Owt%≦(Ti) 10-(Nb)≦2.5wt%
The composition satisfies the following relationship, the remainder consists of unavoidable impurities and Fe, and the Si component segregation rate on the surface of the alloy sheet immediately before etching or press punching of the alloy steel strip, that is, (I) High-strength, low-thermal-expansion Fe-Ni with excellent plating properties, solderability, and repeated bending properties, characterized by a formula of 10% or less
alloy.

(3) The raw materials are mixed to meet the composition described in (1) above, and the steel ingot or continuous casting slab obtained by melting is subjected to plastic working and heat treatment the necessary number of times until the desired shape is obtained, and the final plastic Processing is performed within the range of 10 to 90%, and 500%
10-500 min. in a temperature range of ~800°C. Plating properties, solderability, repeatability, characterized in that the aging treatment of , and the segregation rate of Si on the alloy plate surface just before etching or press punching of the alloy steel strip satisfies the conditions set forth in claim 1. A method for producing a high strength, low thermal expansion Fe-Ni alloy with excellent bending properties.

(4) Blend raw materials to satisfy the composition described in item (1) above, and subject the steel ingot or continuous casting slab obtained by melting to the required number of plastic working and heat treatment until the desired shape is obtained, 10 to 500 min. in a temperature range of 500 to 800°C before final plastic working. aging treatment, followed by a final plastic working rate in the range of 10 to 90%, and the segregation rate of Si on the alloy sheet surface immediately before etching or press punching of the alloy steel strip, or the above (1). A method for producing a high-strength, low-thermal-expansion Fe-Ni alloy with excellent plating properties, solderability, and repeated bending properties, which satisfies the conditions described in .

(5) The raw materials are blended to satisfy the composition described in (2) above, and the steel ingot or continuous casting slab obtained by melting is subjected to plastic working and heat treatment the necessary number of times until the desired shape is obtained, and the final plastic Processing is performed within the range of 10 to 90%, and 500%
10-500 min. in a temperature range of ~800°C. Plating and solderability characterized by performing an aging treatment of , and the segregation rate of Si on the surface of the alloy sheet immediately before etching or press punching of the alloy steel strip satisfies the conditions described in item (2) above. , a method for producing a high-strength, low-thermal-expansion Fe-Ni alloy with excellent repeated bending properties.

(6) The raw materials are blended to satisfy the composition described in item (2) above, and the steel ingot or continuous casting slab obtained by melting is subjected to plastic working and heat treatment the necessary number of times until the desired shape is obtained, and the final plastic Before processing, it is heated in a temperature range of 500 to 800°C for 10 to 500 min. aging treatment, followed by a final plastic working rate in the range of 10 to 90%, and the segregation rate of Si on the alloy plate surface immediately before etching or press punching of the alloy steel strip, or the above (2). Plating properties, solderability, which are characterized by meeting the conditions described in
A method for producing a high-strength, low-thermal-expansion Fe-Ni alloy with excellent repeated bending properties.

(Function) A detailed explanation of the present invention will be given below. First, the reason for limiting the chemical composition of the alloy of the present invention is as follows in terms of wt% (hereinafter simply referred to as %).

Ni is the basic component of the present alloy. In order to achieve the high strength intended in the present invention, Ti, Al, or Ti, N
b (appropriate as described below), the thermal expansion coefficient (from 30 to 300" The average value of
The amount of Ni that satisfies
The range is 39 to 45%. If Ni is less than 39% or more than 45%, the average coefficient of thermal expansion from 30°C to 300°C (hereinafter referred to as α, -1°°C) is 7.4.
Exceeds X 10-@/℃. From the above, the amount of Ni is 39
It was set at ~45%.

Co is Ti5Al or Ti, Nb as described later.
, when AA7 is added properly, the amount of Ni is 39-45%
Within this range, Co has an effect equivalent to that of Ni on the thermal expansion coefficient within the range of 1% or less. On the other hand, C.

If it exceeds 1%, α, regardless of the amount of Ni. -2°.

℃ exceeds 7.4 x 10-'/℃. From the above, C.

The amount was set at 1% or less. There is no particular lower limit, or the amount of Co that can be mixed industrially is 1% or more of O, OO.

When Ti, AA or Ti, Nb, and Ai are appropriately added as described below while Co is within the range of 1% or less, (N
i amount Co) αzo-zo within the range of 40 to 46%.

℃ or 4.0 to 7.4 x 10-'/'C. On the other hand, when the amount (Ni amount Co) is less than 39% or more than 46%, α.

-3°. ℃ exceeds 7.4 X I O-'/'C.

Based on these facts, the amount (Ni content and Co content) was determined to be 39 to 46%.

In addition, α,. -2°. °C is 4.0~7.4 x 10-
Even the range '/'C can be changed by appropriately controlling the amount of Ni, the amount of Co, and the amount of (Ni amount Co) within the range of the present invention according to the thermal expansion coefficient of the base material.

By optimizing the amounts of Ni and Co as described above, the required thermal expansion characteristics can be imparted even when appropriate amounts of Ti, AA7 or Ti, Nb, and AA are added as described below. Low thermal expansion properties, high strength, and
To obtain excellent repeated bending properties, excellent plating properties, and solderability, add appropriate amounts of Ti, lj' or Ti, Al, and Nb, optimize the amounts of Mn and Si, and add p, s, o, N, and C. It is essential to reduce the amount below a certain value.

First, the reason for limiting C, N, S, 0, and P will be described.

When the content of C increases, it forms carbides in the alloy,
Deteriorates plating and solderability. In this case, the degree of deterioration of these properties in this alloy is significantly greater than in conventional Fe--Ni alloys for lead frames, and problems arise with respect to plating properties not only with Ag plating but also with Au plating. Moreover, if the amount of C is large, hot workability and repeated bending characteristics will deteriorate.

That is, when the amount of C exceeds 0.0100%, the Au plating property
Since Ag plating properties, solderability, hot workability, and repeated bending properties deteriorate, from these points of view, the upper limit is set at 0.0100%. In addition, in order to further improve Au plating property, Ag plating property, and solderability, the preferable amount of C is 0, 0 O5
It is 0% or less.

When the content of N increases, nitrides precipitate at the grain boundaries, and this element has a particularly negative effect on the plating properties and solderability of the present alloy. If the amount of N is large, hot workability will also deteriorate. Au plating properties, Ag plating properties, solderability, and hot workability deteriorate when N exceeds 0.0030%, so 0.0 O3
The upper limit is 0%. In addition, in order to further improve Au plating property, Ag plating property, and solderability, the preferable amount of N is 0.
OO is 15% or less.

S is an element that segregates at the austenite grain boundaries in the alloy, embrittles the grain boundaries, and significantly deteriorates the hot workability of the present alloy. Also, if the amount of N is large, inclusions in the alloy will increase,
The plating and solderability of this alloy will deteriorate. hot workability,
N to improve Au plating property, Ag plating property, and solderability
The amount of O, OO is 30% or less. In addition, more preferable S for improving these plating properties, solderability, and hot workability.
, is 0, OO10% or less.

0 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 this amount is 0 or too large, inclusions in the alloy will increase, and A
U plating properties, Ag plating properties, and solderability deteriorate. The amount of C for improving hot workability, Au plating property, Ag plating property, and solderability is 0.0040% or less, more preferably 0.0040% or less.
0025% or less.

Note that even when the amount of 0 is within the range of the present invention, in the present alloy, control of the form of inclusions is more important than Au plating property, Ag plating property, solderability, etching workability, and press punching property. That is, the amount of T102 in the inclusions was reduced by 50%.
By doing the above, the inclusions can be made into fine particles, and by making the size of the inclusions 5 μm or less in the alloy thin plate just before etching or just before punching, A
U plating properties, Ag plating properties, solderability, etching workability, and press punching properties can be improved, and in the present invention, control of such inclusions is also an important component.
It is.

P is an element that segregates at austenite grain boundaries in the alloy, embrittles the grain boundaries, and deteriorates hot workability. Also,
When the amount of P increases, surface segregation of P occurs during heat treatment of the alloy steel strip, resulting in deterioration of Au plating properties, Ag plating properties, and solderability. The amount of P for improving hot workability is 0.0100
% or less. Further, the amount of P for improving Au plating properties, Ag plating properties, and solderability is also 0.0100% or less, more preferably 0.0040% or less.

In this alloy, Si is used as a deoxidizing material or 0.
If it exceeds 30%, a non-uniform oxide film will be formed during heat treatment of the alloy steel strip, and the Au plating properties, Ag plating properties, and solderability will deteriorate, so the upper limit for Si was set at 0.30%.

Note that even if the Si amount is within this range, S on the alloy plate surface
If the component variation of i is large, there will be regions where the Au plating performance, Ag plating performance, and solderability deteriorate locally, and as a result, problems will arise in these plating properties, so such component fluctuations must be controlled. . Therefore, in the present invention, the above Si
In addition to specifying the amount, by setting the component segregation rate of Sl on the alloy plate surface immediately before etching or press punching, that is, to 10% or less, A
Solve local deterioration of U plating, Ag plating, and solderability. Even if the Si component segregation rate is 10% or less, if it exceeds 0.30% at the maximum concentration, Au plating performance, Ag plating performance, and solderability will deteriorate. control so that it does not become a problem.

Mn is an element that improves the hot workability of this alloy, and has a content of 0.
If it is less than 1%, no effect will be obtained, while if it exceeds 0.7%, a non-uniform oxide film will be formed during heat treatment of the alloy steel strip, resulting in poor Au plating properties, Ag plating properties, and solderability. Based on the above, the lower limit of Mn was determined to be 0.1%, and the upper limit was determined to be 0.7%.

In the present invention, as described above, optimization of Ni and Co amounts, M
In addition to optimizing the amounts of n and Si and reducing C, N, S, 0, and P to below specific values, by adding appropriate amounts of Ti and Al, it is possible to achieve the same level as conventional alloys as intended by the present invention. Low thermal expansion characteristics, plating and solderability, and higher strength than conventional alloys.
Excellent repeated bending properties can be obtained.

In other words, the addition of an appropriate amount of Ti is the reason for the addition of an appropriate amount of AI, which will be described later.
Achieves high strength while maintaining U plating properties, Ag plating properties, solderability, and required low thermal expansion characteristics. The intended effect of the present invention is that the hardness (Hv) is 280 or more, the number of blisters after heating after Au plating is 1/4aiJd or less, and the number of blister after heating after Ag plating is 1 or less. pcs/4 cffl or less, solder wetting time t2 or less than 1.0 seconds, α3G-300″C or 4.0 to 7.4 X 10
-'/°C.

In other words, if Ti is less than 1.0%, high strength (Vickers hardness of 280 or more) is achieved as intended by the present invention as described below.
On the other hand, if T1 exceeds 3.0%, the average thermal expansion characteristic α3°-3°. ℃ or exceeds 7.4 X I O-'/℃ even in the Ni amount and CO amount range of the present invention, and A
U plating properties, Ag plating properties, solderability, and repeated bending properties are below the level intended in the present invention as described later.

From the above, the appropriate addition amount when adding Ti alone is 1.0
It was set at ~3.0%.

In addition, A[ is added in combination with the above-mentioned appropriate amount of Ti, thereby achieving the high strength, repeated bending properties, Au plating properties, Ag plating properties, solderability, and low thermal expansion properties intended in the present invention. be done. In other words, if the Al content is less than 0.10%, the high strength intended in the present invention cannot be achieved;
, 20%, the Au plating properties, Ag plating properties, solderability, and low thermal expansion properties fall below the levels of the present invention. Based on the above, the appropriate amount of Al added was determined to be 0.10 to 0.20%.

In the present invention, when Nb is added in combination in addition to Ti, the strength can be increased higher than when Ti is added alone for the same amount of Ti.

That is, each of the diagrams (a) to (C) in FIG.
Hv), average coefficient of thermal expansion (α, -3°.'C) and T
The relationship between i, Nb, and AI amounts is shown. Each characteristic value is N
1, Co, P, S, 0, N, C, Mn, Si,
Solution treatment - cold rolling - solution treatment - final cold rolling (3゛0%) of a hot rolled sheet of an alloy whose Si segregation rate is within the range of the present invention
- Aging treatment (600°C x 2 hours) - An alloy plate subjected to surface oxidation layer removal treatment was examined. Au plating properties, Ag plating properties, hardness after aging, and average coefficient of thermal expansion were investigated by the method shown in Example 1 described below.

In the case of 0.10%≦1'≦0.20% in FIG. 1(b), when both Ti and Nb are within the specified range of the present invention, excellent solderability, Au plating property, Ag plating property, Higher age hardening amount (Hv≧300), thermal expansion coefficient intended in the present invention (α1-ff00″C=4.0~7.4 Xl0-
”/'C), excellent repeated bending properties (number of repeated bends,
4 or more times) or at the same time. On the other hand, when l < 0.10% in (a) or AA > 0.20% in (c) of the same figure, there is no region where all the effects intended by the present invention can be obtained. The range is outside the scope of this invention.

From the above, Ti and Nb satisfy all of the excellent solderability, Au plating property, Ag plating property, higher amount of age hardening, required low thermal expansion property, and repeated bending property intended in the present invention.
, AI! As the amount, 0.10%≦Al≦0.20%
, 0.5%≦Ti≦2.0%, 0.05%≦Nb≦2.
0%, 1.0%≦(Ti) ten-shaped (Nb)≦2.5%.

In addition, in the present invention, unless otherwise specified, Cr,
Co, W, Cu, and Mo are elements that deteriorate thermal expansion characteristics, and their contents are 0.5% or less, 0.3% or less, respectively.
By setting the content to 0.5% or less, 0.1% or less, or 0.5% or less, the effects of the present invention can be exhibited without being inhibited. Therefore, in the present invention, Cr is 0.5% or less, Co
Contents of 0.3% or less, Wo, 5% or less, and Cu 0.1% or less are allowed.

In addition, in this alloy, Mg, Ca, B, Zr
When added in an appropriate amount, hot workability can be further improved without inhibiting the effects intended by the present invention.
Alloys to which Mg, Ca, B, and Zr are added are also included in the present invention. In this case, Mg,
The sum of one or more types of Ca, B, and Zr is 0, 0
By setting the I O to 0% or less, the effects intended by the present invention are not inhibited, and hot workability can be further improved.

Regarding the manufacturing method of the present invention, melting can be performed by vacuum melting (VIM), electric furnace melting, vacuum arc melting (
Any method such as VAR), electroslag melting (ESR), or electron beam melting (EBR) may be used. In particular, by using a vacuum melting furnace and VARlESR, impurity components can be further reduced, which is advantageous from the viewpoints of Au plating properties, Ag plating properties, and solderability as intended by the present invention. In addition, by appropriately performing refining after the above-described melting, the above-mentioned impurity components can be further reduced.

The alloyed molten steel whose composition has been adjusted is cast into a steel ingot by the ingot-forming method, a CC slab by the continuous casting method, or a thin slab by the rapid solidification method.

The steel ingot CC slab and thin slab thus obtained are plastically worked until they have a desired shape. Plastic working methods include hot working, warm working, and cold working. Hot working includes blooming and forging of steel ingots and CC slabs, and hot rolling of slabs and thin slabs. The alloy steel strip obtained by the above method is further removed from scale and internal oxidation layers, and then processed to the thickness of the final product by a combination of one or more of warm working and cold working. At this time, warm processing,
One or more heat treatments may be applied during cold working. In this case, heat treatment is performed for the purpose of softening the present alloy, more preferably for converting T1, An, Nb, etc., which are the main components of the present alloy, into a solid solution. is selected from 950°C to 1150°C when solid solution formation is intended. This alloy recrystallizes at temperatures above 750°C and becomes a solid solution at temperatures above 950°C. Note that if the temperature exceeds 1150°C, coarsening of crystal grains occurs and plastic workability deteriorates, so the upper limit temperature of the heat treatment must be 1150°C or less. Note that the final plastic working may be performed by warm working or cold working, but cold working is particularly preferred over Au plating, Ag plating, and soldering. Cold rolling is also preferable for this cold working from the viewpoint of manufacturing efficiency.

One method for further reducing the segregation of Si components is to optimize the heating temperature, heating time, and processing conditions during blooming rolling. In other words, when blooming a steel ingot by the ingot-forming method or a slab by continuous casting, in the case of 1-heat blooming in which heating and rolling are performed only once, (T is the heating temperature and t is the heating holding time. (hereinafter simply referred to as T and t)), perform blooming and rolling at a cross-section reduction rate of 35% or more, and slowly cool after rolling. As a result, the Si component segregation rate can be made 10% or less, and the amount of defects removed from the slab obtained by blooming rolling can be made 5 mm or less.

Note that if the lower limit of formula (■) is not met or if formula (■) is not satisfied, the segregation rate of Si at the final plate thickness will exceed 10%, which is unsuitable.

Moreover, when the upper limit of formula (V) is exceeded or formula (■) is not satisfied, the amount of flaws removed (per one side) of the slab after blooming exceeds 5 mm, resulting in poor hot yield.

Furthermore, when blooming the steel ingot or continuous casting slab, in the case of two-heat blooming in which heating and rolling are performed twice, it is possible to lower the level of Si microsegregation compared to one heat. . In this case, 1150≦T('C)≦1300...(■) Formula log
t≦7.40-5.33XIO-”T...(IX
) formula log t≦7.71-5.33 X 10-”
T... Heating under the conditions that satisfy formula (X) to formula
After rolling, it is reheated under conditions that satisfy the above three formulas, and then in the second blooming rolling, the area reduction rate is 20 to 7.
By processing within the 0% range and slow cooling after processing, the segregation rate of Si can be reduced to 10% or less, and the amount of defects removed from the slab obtained by blooming rolling is 5 mm or less. I can do it.

If the lower limit of formula (■) or formula (IX) is not satisfied, the Si segregation rate at the final plate thickness will exceed 10%, which is inappropriate.

In addition, if the upper limit of formula (■) is exceeded or if formula (X) is not satisfied, the amount of defects removed (per one side) of the slab after blooming is 5
-, the hot yield is poor.

Furthermore, in addition to the above-mentioned methods, methods for reducing Si component segregation to the level intended by the present invention include prevention of segregation during ingot production, specifically, rapid solidification (casting into thin slabs), and prevention of segregation during casting. Shortening the solidification time by using electromagnetic stirring, unidirectional solidification, light reduction casting, and flat steel ingots, or performing one or more of each of hot working, warm working, and cold working during the strip manufacturing process. This can also be achieved by a combination of heat treatments.

Regarding the above-mentioned alloy of the present invention, the Au plating property, Ag plating property, solderability, low thermal expansion property, high strength, and excellent repeated bending property as intended by the present invention are achieved by adjusting the manufacturing conditions in addition to the above composition specifications. It can be further improved by making it more appropriate.

In other words, the intended effects of the present invention can be sufficiently achieved by optimizing the final cold rolling rate when forming the desired shape (plate thickness) and the aging treatment performed before or after the final cold rolling.

Figures 2 and 3 show the hardness (f(v), repeated bending properties, Au plating properties, Ag plating properties, The results of examining the properties, solderability, and average coefficient of thermal expansion are plotted against the final cold rolling reduction.

Table 2 Manufacturing conditions for test materials 8° In all methods, solution treatment, aging treatment, and strain relief annealing were performed in a non-oxidizing atmosphere.

From Figure 2, regardless of whether the manufacturing method is method A or method B, the final cold rolling reduction is 10% or more, Hv300 or more, tensile strength 100 kgf /mm2 or more, and 0.2% proof stress 8.
0kgf/=2 or more, while the final cold rolling rate is 9
0% or less indicates repeated bending characteristics of 4 times or more.

Furthermore, as shown in Fig. 3, when the final cold rolling rate is 90% or less, the Au plating property and Ag plating property are good with the number of blisters being 1 piece/4d or less, and the solderability is also good at a wetting time t2 of 1.0 seconds. The following is good. Also, the coefficient of thermal expansion α, -2°. ℃ is 4.0 to 7 even at the final cold rolling rate or within the range of the present invention.
．． It is within the range of 4 x 10-'/°C.

From the above, the present invention exhibits low thermal expansion characteristics, Au plating properties, Ag plating properties, solderability, superior high strength, and excellent repeated bending properties. As the final rolling rate, 10 to 9
0% was set.

Note that even if the final cold rolling rate is within the range of the present invention, the required strength, repeated bending properties, Au plating properties, and A
Depending on g-plating property and solderability, the radius can be controlled arbitrarily by optimizing the final cold rolling rate and aging treatment conditions. In particular, when the aging treatment is performed before the final cold rolling, the solderability is better (the solder wetting time t2 is shorter) than when the aging treatment is performed after the final cold rolling.

The aging treatment performed before or after the final cold rolling is performed at a temperature of 500 to 800°C for a time of 10 to 500 min. It is necessary to keep it within the range of .

If the temperature is less than 500°C or more than 800°C, the high strength (Hv 280 or more) intended in the present invention cannot be obtained.

This is because if the temperature is less than 500°C, the particles contributing to precipitation hardening will not be sufficiently precipitated, while if it exceeds soo'c, the size of the particles will become too large, and sufficient precipitation hardening will not be achieved in either case. Note that when the temperature exceeds 800° C., deterioration of Au plating properties, Ag plating properties, and solderability also occurs due to coarsening of the particles.

Also, even if the temperature is within the range of 500 to 800℃,
0 min. or less than 500min. If the strength is too high, the high strength (Hv280 or higher) intended in the present invention cannot be obtained.

In other words, the time is 10 min. If the time is less than 500 min., the particles will not be sufficiently precipitated. This is because the size of the particles becomes too large and sufficient precipitation hardening cannot be obtained in any case.

Note that the time is 500 min. at a temperature within the specifications of the present invention. In the case of super, Au plating property due to coarsening of the particles, Ag
Deterioration of plating properties and solder properties also occurs. Further, when aging conditions within the specifications of the present invention are adopted, the low thermal expansion characteristics, excellent repeated bending characteristics, Au plating properties, Ag plating properties, and solderability intended by the present invention are imparted.

From the above, the conditions for aging treatment performed before or after final cold rolling are as follows: temperature 500-800°C 1 hour 10-5
00m111 was determined.

Note that even when the aging conditions are within the range of the present invention, the temperature and time required to obtain the same strength can be made shorter as the temperature becomes higher.

Now, in the production of this alloy, prevention of edge cracking during cold rolling is important for improving yield during production. That is, since this alloy contains reinforcing elements such as 11, Af, Ti, Nb, and Al, the strength of the matrix is high, and furthermore, if precipitation hardening of the elements occurs in the cold-rolled material, The strength of the matrix increases and cold workability deteriorates. Therefore, in order to improve cold workability and suppress etch cracking during cold rolling, it is particularly important to optimize hot rolling conditions.

In other words, the heating temperature in hot rolling is 1300°C to 1200°C, and the total rolling reduction rate at 1000°C or higher is 80% or more, 850°C.
The total rolling reduction rate at ℃ or higher is 95% or more, and the rolling end temperature is 8
By setting the temperature to 00° C. or higher, the hot-rolled coil can be sufficiently recrystallized (recrystallization rate 80% or higher) and can be made into fine austenite grains with an austenite grain size of Nα7 or higher. Furthermore, by setting the winding temperature of the coil after hot rolling to 500° C. or lower, age hardening during the cooling process of the hot rolled coil can be suppressed. The hot rolled coil (cold rolled material), which has been sufficiently recrystallized to have a fine grain structure and suppressed age hardening, has excellent cold workability, and etch cracks do not occur even during cold rolling. Very few.

In addition, in the present invention, the plastic working of the hot rolled coil is not limited to cold rolling, but may also be warm rolling, and even such warm rolling may satisfy the structural requirements specified in the present invention. In this case, the effects intended by the present invention can be fully exhibited.

In the production of this alloy, the solution treatment applied to the hot-rolled coil or cold-rolled coil (warm-rolled coil) is carried out at a temperature of 950 to 1100°C for a time of 10 sec -10
min. Depending on the conditions, it is possible to convert TI, Nb, Af, etc. into a solid solution. In order to improve the surface quality, it is preferable to perform solution treatment in a non-oxidizing atmosphere in order to improve the cleanliness of the surface. The cleanliness of the surface can be improved, and the Au plating property, Ag plating property, and solderability of the product can be further improved. In addition, in order to improve the surface quality, the aging treatment is preferably carried out in a non-oxidizing atmosphere, and after the aging treatment, the oxide film on the surface is removed to further improve the cleanliness of the surface. Kotakadeki, the Au plating property of the product,
It is possible to further improve Ag plating properties and solderability.

In addition, in manufacturing this alloy, warping during etching,
Problems such as flickering of the lead portion after press punching are likely to occur. Since these problems are caused by residual stress within the alloy plate, it is desirable to perform treatment to remove residual stress after aging treatment or final plastic working.

Furthermore, the plating properties of the present alloy thin plate can be further improved by performing a base plating treatment after the above-mentioned surface oxide film removal treatment. The composition of this base plating is selected from Cu, Ni, alloys thereof, and the like.

(Example) Specific examples of the present invention will be described below.

Example 1 The composition was adjusted in a vacuum melting furnace to obtain a steel ingot of an alloy (sample material Nαl~22) having the chemical composition shown in Table 3.

After cleaning the steel ingots with the chemical composition of the test materials Nα1 to Nα22 obtained as described above, they were heated at 1200°C for 20 hours,
Perform blooming rolling at a cross-section reduction rate of 60% in the primary blooming, then heat at 1200°C for 20 hours, perform blooming rolling at a cross-section reduction rate of 45% in the secondary blooming, and slowly cool. A slab was obtained.

In addition, sample material Nα23 was obtained by heating a steel ingot having the same composition as sample material Nα2 at 1200°C for 15 hours after cleaning.
A slab was prepared by performing blooming rolling with a reduction in area of 78% and slow cooling. H, S in the atmospheric gas of the heating furnace
The concentration is 60 ppm.

After cleaning these slabs and coating them with an antioxidant, they were heated at a heating temperature of 1100° C. and then hot rolled. At this time, the total rolling reduction at 1000°C or higher is 82%, the total rolling reduction at 850°C or higher is 98%, and the hot rolling end temperature is 850°C. The coil winding temperature was 300-450°C. The occurrence of surface defects on the slab was investigated by visual observation and color check.

After descaling the hot-rolled coil obtained as above,
Plate thickness 0 with the required surface roughness under the conditions shown in Table 4 below
．． A 15 mm alloy plate was obtained.

Table 4 Manufacturing conditions for test materials 1 In all cases, solution treatment, aging treatment, and strain relief annealing were performed in a non-oxidizing atmosphere.

The segregation rate of Sl on the plate surface of each alloy plate as described above is E
This was investigated using a mapping analyzer (area analysis) using PMA.

Silver plating properties were determined by pre-treating the alloy thin plate by degreasing and pickling, then applying Ag plating to a thickness of 3 μm, and then heating at 450°C for 3 minutes.
．． The test was carried out by heating in the atmosphere and examining the occurrence of plating blisters under 50 times magnification.

The gold plating property was determined by pre-treating the alloy thin plate by degreasing and pickling, then applying Au plating to a thickness of 2 μm, and then heating at 450°C x 3 mjn.
The sample was heated in the atmosphere, and the presence or absence of plating blistering was examined by magnifying the sample 50 times.

Solderability was determined by the meniscograph method using the thin alloy plate plated with tin to a thickness of 1.5 μm, and the solder composition was 5N60%, Pb40%, and the solder bath temperature was 235°C.
It was immersed in a solder bath under the conditions of ±5° C., solder bath immersion depth of 2 balls, and solder bath immersion time of 5 seconds, and evaluation was performed at solder wetting time t2.

Average coefficient of thermal expansion, tensile properties (0.2% proof stress, tensile strength,
The elongation at break), Vickers hardness, and repeated bending properties were also measured by taking test pieces from the alloy plate.

The repeated bending characteristics were determined by cutting out a test piece with a width of 0.5 mm at an angle of 90' with the rolling direction of the alloy plate, placing it in a jig with a plate thickness of R, bending it by 90 degrees, returning it to its original state, and was counted as one cycle, and the number of cycles until it broke repeatedly on the same side was counted.

These results are shown in Table 5 below.

The evaluation of plating properties and surface flaw occurrence in Table 5 is as follows.

1) Au plating property: ◎Number of bulges: 0 pieces/4cm○
〃 1 piece/4cnr △ 〃 2~4 pieces/4cJ × 〃 5 pieces/4al 2) Ag plating property: ◎ Number of blisters 0 pieces/4cffl
○ 〃 1 piece/4al △ 〃 2-4 pieces/4al × 〃 5 pieces/4cnr 3) Surface flaw occurrence: ◎ Very few ○ Few △ Many Ni
+Co, 11, Si, P, S, 0, N,
C, Ti, Nb, (Ti) + (Nb), AC
The segregation rate of Si is within the specifications of the present invention, and the thermal expansion coefficient α*
o -300'C is 4.0 to 7.4 X 10-'/'
The C1 hardness is Hv280 or more, the repeated bending property is 4 times or more, and the Au plating property, Ag plating property, and solderability (solder wetting time i2) are at a superior level compared to the comparative materials described below. The effect of this is being demonstrated. Furthermore, the occurrence of surface flaws in these test materials was less than in the comparative materials described below, which indicates that these test materials had essentially superior hot workability. Incidentally, it is known from experience that when hot rolling workability is poor, surface defects occur frequently in the slab after blooming.

In particular, the test material Nαl,2 has P, S, 0, N, and C reduced to a more preferable level, and the Au plating property and Ag
Plating properties and soldering properties (solder wetting time t2) are at an excellent level. Further, the sample Nα3 material is a case in which B and Ca are added in small amounts, and this material has extremely few surface defects and exhibits the effects intended by the present invention described above. Moreover, in addition to Ti, Nb was added to the sample material Nα2.3 within the limits of the present invention, and a higher strength was achieved compared to the sample material Nα1.4.

On the other hand, the sample materials Nα5.6.7 have N1
The average coefficient of thermal expansion α30-20
Q°C exceeds 7.4 x 10-'/°C, and there is a problem with thermal expansion characteristics.

The Mn of the sample material Nα8 exceeds the upper limit defined by the present invention, and the Au plating properties, Ag plating properties, and solderability are inferior to those of the present invention examples. The sample material Nα9 has Mn less than the lower limit defined by the present invention, has extremely many surface defects, and is found to have poor hot workability.

Each of the sample materials Nα10, ]1, ]2.13.14, and ]5 has Si, P, S, 0, N, and C exceeding the upper limit values stipulated in the present invention, and has poor Au plating properties. , Ag plating properties, and solderability are inferior to those of the examples of the present invention. In addition, sample materials Nα11, 12, and 13 had extremely many surface defects and were poor in hot workability.

Furthermore, deterioration of repeated bending characteristics was observed in the sample Nα15 material.

Sample material Nα] Each village of 6.18.19.21 was
Ti, Nb, (Ti) +'A (Nb), A A
' or exceeds the upper limit defined by the present invention, and Au plating properties, Ag plating properties, and solder properties are inferior to those of the examples of the present invention. In addition, the thermal expansion coefficient α for Nα19 material. -3゜o
'c exceeds the upper limit specified in the present invention.

Each village of sample material Nα17, 20, 22 has Ti,
(Ti) 10% [:Nb), AA is less than the lower limit defined by the present invention, and the hardness (Hv) is less than 280, which does not provide the high strength intended by the present invention.

Sample material Nα23 has a Si segregation rate exceeding the upper limit defined by the present invention, and is inferior to the examples according to the present invention in terms of Au plating property, Ag plating property, and solderability.

As described above, it can be seen that even in the high-strength Fe--Ni alloy for lead frames, the effects intended by the present invention can be obtained only under the control of the composition and Si segregation rate defined by the present invention. In particular, the alloy featured in the present invention has inherently high hot workability even when methods other than blooming rolling are used to reduce the segregation rate of Sl, so it is It also has the advantage of high yield during the manufacturing process. For example, even when molten steel of this alloy is rapidly cooled and solidified to produce a thin slab, surface defects are extremely rare and the yield is high.

In addition, the following Table 6 shows the sample material NCL used in this Example 1.
The results of measurement of inclusions in alloy plates of I to Nα22 are shown. Sample material N (11-Nα4), which satisfies the composition specifications of the present invention, is superior to other comparative examples, and there are no spherical or linear inclusions. ,
When I looked at the thickness, I couldn't see anything over 3 μm. Nα1
The composition of the ~Nα4 inclusions contained 50% or more of TiO□.

The basic idea of the present invention is to create an alloy in which fine-grained inclusions are dispersed by having such an inclusion composition and by controlling the level of impurity elements within the specifications of the present invention. By the way, when the materials of test materials Nα1 to Nα4, which are examples of the present invention, were processed into lead frames by press punching or photo etching, the punching properties were good, the etching end surfaces were smooth, and the etching properties were also good. Ta.

The hot-rolled coil manufactured as in this example has a recrystallization rate of 90% and a fine austenite grain size of Nα8.
Age hardening during the coil cooling process was suppressed. The cold workability of these coils was good, and the occurrence of edge cracking was extremely low even during cold rolling.

In addition, the residual stress of the alloy plates subjected to strain relief annealing as in this example is extremely small, and when these alloy plates are press-punched, the flickering of the leads is so small that it does not pose a problem in actual manufacturing. Even in this case, the warpage after etching was extremely small and was at a level that caused no practical problems.

In addition, in the present invention material, copper (or Ni) before silver plating is used.
) is characterized by good silver plating properties even without strike plating.

By performing copper (or Ni) strike plating before the silver plating described above, the thickness of the silver plating can be made even thinner than the plating thickness described above.

Example 2 A steel ingot of the invention alloy having the same composition as the test material Nα2 in Example 1 was manufactured under the manufacturing conditions shown in Table 7 to produce a plate with a thickness of 0.
．． A 15 mm alloy plate was obtained. Note that the final cold rolling reduction and aging conditions are as shown in Table 8.

Table 7 Manufacturing conditions of sample materials.

0 In all methods, solution treatment, aging treatment, and strain relief annealing are performed in a non-oxidizing atmosphere.

Table 8 Si segregation rate, average coefficient of thermal expansion, tensile properties, Vickers hardness, repeated bending properties, Au plating properties, Ag plating properties,
Solderability was determined using the same method as described in Example 1. These results are shown in Table 9 below.

"Effects of the Invention" According to the present invention as described above, Fe-Ni alloy suitable as a lead frame material for multi-pin IC,
In other words, it has higher strength than conventional alloys, excellent repeat bendability, and low thermal expansion properties equivalent to conventional alloys.
It is possible to provide an alloy with excellent Au plating properties, Ag plating properties, and solderability, and a preferable manufacturing method thereof.Furthermore, the alloy has excellent hot workability and a high yield during production. This invention has the following effects and is of extremely great industrial value.

[Brief explanation of the drawing]

The drawings show the technical content of the present invention, and Figure 1 shows Au plating properties, Ag plating properties, and hardness after aging (Hv).
, average coefficient of thermal expansion ((r*o-****℃) and Ti,
A diagram showing the relationship between the amounts of Nb and AA, (a) is AI<0
．． 10%, (b) is 0.10%≦Al≦0.20%, (
C) shows the case where Al>0.20%, and Figure 2 is a chart showing the relationship between each mechanical property and the final cold rolling rate.
FIG. 3 is a chart showing the relationship between Au plating property, Ag plating property, solderability, average coefficient of thermal expansion, and final cold working rate for the same alloy composition and manufacturing method as in FIG. 2. Patent applicant Nippon Steel Tube Co., Ltd. Inventor Bowl Upper Masaaki Kinoshita Masaru Line spacing
Satoshi Ohkita Meal 1 yen (α) AN<0.10% Nb (wt%)'! fJ 1m (b) 0.10%≦A flood≦0.20%Nb (wt
%)! ls1m (c) Aln○Nod% Nb (wt%) 'I/531iI Final cold rolling-T4 (%)

Claims (1)

[Claims] (1) Ni: 39-45 wt%, Ni+Co: 39-4
6wt%, Co: 1.0wt% or less, Mn: 0.1-0
．． 7wt%, Si: 0.30wt% or less, Al: 0.1
0 to 0.20wt%, P: 0.010wt% or less, S:
0.0030wt% or less, O: 0.0040wt% or less, N: 0.0030wt% or less, C: 0.0100wt
% or less, Ti: 1.0 to 3.0 wt%, the remainder consists of inevitable impurities and Fe, and the Si content on the alloy plate surface immediately before etching or press punching of the alloy steel strip. Segregation rate, i.e. | (component concentration in segregation area - average component concentration) / (average component concentration) | High strength, low thermal expansion Fe-Ni with excellent bending properties and repeated bending properties
alloy. (2) Ni: 39-45 wt%, Ni+Co: 39-4
6wt%, Co: 1.0wt% or less, Mn: 0.1-0
．． 7wt%, Si: 0.30wt% or less, Al: 0.1
0 to 0.20wt%, P: 0.010wt% or less, S:
0.30wt% or less, O: 0.0040wt% or less, N
: 0.0030 wt% or less, C: 0.0100 wt% or less, Ti: 0.5 to 2.0 wt%, Nb: 0.05 to 2
．． 00wt%, 1.0wt%≦[Ti]+1/2[Nb]≦2.5wt
%, and the remainder consists of unavoidable impurities and Fe, and the Si component segregation rate on the alloy plate surface immediately before etching or press punching of the alloy steel strip, that is, |(average concentration in the segregation area - Average component concentration)/(average component concentration) | Fe-Ni
alloy. (3) A steel ingot or continuous casting slab obtained by blending and melting raw materials to satisfy the composition described in claim 1 is subjected to plastic working and heat treatment a necessary number of times until the desired shape is obtained, and final plastic working is performed. Applied within the range of 10-90%, 500-8
10 to 500 min. in a temperature range of 00°C. Plating properties, solderability, repeated bending, characterized in that the aging treatment is performed, and the segregation rate of Si on the alloy plate surface just before etching or press punching of the alloy steel strip satisfies the conditions set forth in claim 1. A method for producing a high strength, low thermal expansion Fe-Ni alloy with excellent properties. (4) A steel ingot or continuous casting slab obtained by blending and melting raw materials to satisfy the composition described in claim 1 is subjected to plastic working and heat treatment a necessary number of times until the desired shape is obtained, and before final plastic working, 10 in the temperature range of 500 to 800℃
~500min. According to claim 1, the aging treatment is performed, and then the final plastic working rate is applied in the range of 10 to 90%, and the segregation rate of Si on the alloy plate surface immediately before etching or press punching of the alloy steel strip is A method for producing a high-strength, low-thermal-expansion Fe-Ni alloy that satisfies the following conditions and has excellent plating properties, solderability, and repeated bending properties. (5) A steel ingot or continuous casting slab obtained by blending and melting raw materials to satisfy the composition described in claim 2 is subjected to plastic working and heat treatment a necessary number of times until the desired shape is obtained, and final plastic working is performed. Applied within the range of 10-90%, 500-8
10 to 500 min. in a temperature range of 00°C. Plating properties, solderability, repeated bending, characterized in that the aging treatment is performed, and the segregation rate of Si on the alloy plate surface just before etching or press punching of the alloy steel strip satisfies the conditions set forth in claim 1. A method for producing a high strength, low thermal expansion Fe-Ni alloy with excellent properties. (6) A steel ingot or continuous casting slab obtained by blending and melting raw materials so as to satisfy the composition described in claim 2 is subjected to plastic working and heat treatment a necessary number of times until the desired shape is obtained, and then before final plastic working. 10 in the temperature range of 500 to 800℃
~500min. According to claim 1, the aging treatment is performed, and then the final plastic working rate is applied in the range of 10 to 90%, and the segregation rate of Si on the alloy plate surface immediately before etching or press punching of the alloy steel strip is A method for producing a high-strength, low-thermal-expansion Fe-Ni alloy that satisfies the following conditions and has excellent plating properties, solderability, and repeated bending properties.