JP3383549B2 - Method for producing Fe-Ni alloy thin plate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an Fe-Ni alloy thin plate, and in particular, by hot rolling , a Fe-Ni alloy alloy material having a high quality can be obtained without impairing its inherent properties. Strengthened, for example for electronic components,
The present invention relates to a method for manufacturing an Fe-Ni alloy thin plate.

[0002]

2. Description of the Related Art It has a low thermal expansion property, and has good workability, corrosion resistance,
Fe-N with excellent characteristics such as sealing and soldering
The i-based alloy is widely used as a material for electronic parts such as lead frames. For example, as the material for the lead frame, Fe-42Ni (42 alloy), Fe-50Ni,
Fe-29Ni-17Co (Kovar) is used, and especially Fe-36Ni is used as a material utilizing low thermal expansion characteristics.
(Invar), Fe-31Ni-5Co (Super Invar), etc. are used.

Along with the progress of miniaturization and high functionality of electronic equipment, there is a further demand for thinning and fine processing of raw materials. In the Fe-Ni alloy electronic component material finely processed by such a thin plate, due to insufficient strength, conveyance,
During handling of assembly and mounting, bending and warping are likely to occur, and situations such as deformation due to slight impact are likely to occur.
Therefore, further improvement in the strength of the Fe-Ni alloy material is required. However, the strength improvement is Fe
It should not impair the other excellent properties of the Ni-based alloy.

The Fe-Ni alloy strip is generally manufactured through a series of processes including melt casting, hot rolling, one or more cold rolling, and one or more annealing. Cold rolling and annealing are repeated, and after final annealing, final cold rolling is performed. The final cold rolling is cold rolling that is not subsequently annealed at a recrystallization temperature or higher, and determines the final plate thickness. After that, strain relief annealing is often performed below the recrystallization temperature. Recently, thin Fe-Ni alloy strips having a thickness of 0.10 to 0.15 mm are manufactured.

For example, various measures have been proposed for increasing the strength of the 42 alloy strip or a method for producing an alternative alloy thereof, but the reinforced 42 alloy strip or its alternative alloy strip is currently used as a material for electronic parts such as lead frames. In order to maintain compatibility with the component manufacturing process, it is desirable to maintain various properties other than strength as good as the current 42 alloy. To this end, it is considered that the strengthening measure based on the refinement of the grain structure and the dislocation lower structure introduced by working is the easiest.

[0006] In line with this way of thinking,
There have been proposals for refinement of crystal grains and dislocation substructures by optimizing each condition of cold rolling and subsequent annealing, and they are said to be effective as a strengthening measure. For example, JP-A-4-160
No. 112 is the final annealing of the Fe-Ni alloy with a workability of 4
After performing 0 to 90% rolling, it is performed under the condition that the crystal grain size is 30 μm or less, and the workability of the subsequent final cold rolling is adjusted to 40 to 85%.
It is described that a high-strength lead frame material excellent in sealing property and moldability can be obtained. Japanese Unexamined Patent Publication No. 9-41095 discloses an Fe-Ni-based electronic component material containing Ni: 28 to 55% or further Co: 12% or less without impairing solderability and plating property and significantly increasing the cost. As a manufacturing method to obtain sufficient high strength,
Described to perform the final cold rolling at a rolling rate corresponding to the secondary work hardening region where the hardness rapidly increases with respect to the rolling rate,
As a result, it has a structure in which crystal grains are expanded through rolling in the secondary work hardening region, and the hardness is HV ≧ 220 + 0.5 [Ni]% or HV ≧ 220 + in terms of Vickers hardness.
It is said that a material satisfying 0.5 [Ni]% + 0.7 [Co]% can be obtained.

[0007]

However, in the strengthening method by optimizing each condition of these cold rolling and subsequent annealing, the strengthening level has its own limit, and a technique for further effective strengthening is established. Is required to do so. An object of the present invention is to establish a technique capable of increasing the strength of a Fe-Ni-based alloy more effectively than only by optimizing each condition of cold rolling and subsequent annealing.

[0008]

[Means for Solving the Problems] Fe-focusing on hot rolling, which is a basic working process of Fe-Ni alloys,
Up to now, almost no technical studies have been conducted on the strengthening of Ni-based alloys. The present inventors have conducted a series of studies focusing on hot rolling for the purpose of increasing the strength of Fe-Ni alloys, and as a result, performed ingot heating and hot rolling under predetermined conditions. If necessary, perform annealing under prescribed conditions, then repeat cold rolling under appropriate conditions and subsequent annealing, which is more effective than just optimizing each condition of cold rolling and subsequent annealing. It was found that the Fe-Ni alloy can be made stronger. Regarding the conditions of cold rolling under appropriate conditions and subsequent annealing,
For example, the one proposed in Japanese Patent Laid-Open No. 4-160112 can be applied correspondingly.

In the present invention, T _G , T _DR , T _SR and T _R are T _G (° C.) = 0.93 T _m (° C.) and T _DR , respectively, with the melting start temperature of the material being T _m (° C.). (° C.) = 0.
_{5T m +280 (℃), T} SR (℃) = 0.5T m -14
0 (° C.) and T _R (℃) = 0.5T _m is defined as -340 (° C.), the ingot heating temperature: T _H (℃), the hot rolling start temperature: T _RS (℃) and the end of hot rolling Temperature: T _RF (℃)
As a result, the following processing steps (1), (2) and (3) are carried out: (1) an ingot heating step satisfying the condition of T _H <T _G , and (2) (a) -200 ≦ T _DR -T _RS ≤ 200 and T
Hot rolling is performed by satisfying the condition of _RF > T _SR and making the total reduction ratio from T _RS to T _RF to be 70% or more, or (b) −200 ≦ T _DR −T _RS ≦ 200 and T _SR ＞ T _RF ＞
In conditions of T _R, subjected to hot rolling to a total reduction ratio of 70% or more in the range from T _RS to T _SR, further a total reduction ratio of 5% or more in the range from T _SR to T _RF A hot rolling stage in which warm rolling is performed, and (3) after that, cold rolling and annealing are repeated until the crystal grain size after final annealing is less than 10 μm,
Then, a cold rolling stage in which final cold rolling is performed. As a result, it is possible to manufacture a Fe—Ni alloy thin plate having a Vickers hardness of 240 or more and a tensile strength of 800 MPa or more. After hot rolling, annealing can be performed in the temperature range from T _DR to T _SR for 10 minutes to 24 hours. It is preferable that the final annealing is performed after rolling with a workability of 40 to 90%, and the workability of the subsequent cold rolling is adjusted to 40 to 85%.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The Fe-Ni based alloy to which the present invention is related, in its most basic form, contains Ni:% by weight:
It has a composition including 28 to 55% and the balance being substantially Fe. Especially for leadframe materials, it is desirable to control additive components and impurities as follows: C: 0.
015% or less, Si: 0.001 to 0.15%, Mn:
0.1 to 1.0%, P: 0.01% or less, S: 0.
005% or less, O 2: 0.010% or less, N 2: 0.0
05% or less.

The reasons for controlling these components are as follows: Ni Ni is an important component for determining the coefficient of thermal expansion of the lead frame material, and the difference in thermal expansion between the sealing property and the package after sealing. the by reducing, in order to ensure good sealing properties and moisture resistance reliability, it is necessary to adjust the Ni content in the range of 28-55%. A particularly preferred range is 40 to 53%. When the C content in the C lead frame material exceeds 0.015%, iron carbide is generated, which impairs the etching property of the lead frame material. Therefore, the upper limit of the C content is 0.
The content is preferably 015%, but since solid solution C also has an adverse effect on etching processability, the lower the C content, the better, and if possible, it is desirable to suppress it to 0.005% or less. Si 2 Si is an element necessary as a deoxidizing material, but is also an element that has a great influence on the etching workability of the lead frame material. That is, when the Si content increases, the etching rate becomes slow and the etching processability deteriorates. Therefore, in order to secure good etching workability, it is necessary to adjust the Si content to 0.15% or less. Particularly in the case of a multi-pin type lead frame material, better etching workability is required, so it is desirable to reduce the Si content to 0.05% or less. Just S
When i content of reduced to the less than 0.001%, less likely recognized <br/> deoxidizing effect of Si. Therefore, the Si content is 0.0
It is better to set it to 01 to 0.15%, but 0.00 if possible.
It is desirable to adjust it to 1 to 0.05%. Mn Mn is a component added to secure deoxidation and hot workability of the lead frame material, but its content is 0.1.
If it is less than%, not only the desired deoxidizing effect cannot be obtained, but also the hot workability becomes poor. On the other hand, if Mn exceeds 1.0%,
The cause deterioration of the inclusion Workability, more would be larger thermal expansion coefficient. Similar to Si, P P is an element that impairs the etching workability of the lead frame material when the content is high. And
The adverse effect on the etching processability is that the P content is 0.01
%, The P content becomes 0.
It is preferable to set it to 01% or less. However, if the P content is 0.0
If it is reduced to 03% or less, the effect of improving etching workability becomes more remarkable, and even when it is applied to a multi-pin type lead frame, a sufficiently satisfactory result can be stably ensured. It is better to adjust it to below%. If the S S content is more than 0.005%, the sulfide-based inclusions increase in the lead frame material, causing defects during etching and causing pin breakage and the like. Therefore,
The S content is preferably 0.005% or less. In addition to O and N , when the O content exceeds 0.010%, oxide-based inclusions increase in the lead frame material, which also results in perforation defects during etching, so the O content is 0.0.
It is better to be 10% or less. Further, the N content is 0.00
The upper limit of the N content is preferably 0.005% because the etching workability of the lead frame material deteriorates even if it exceeds 5%.

According to the present invention, the melting start temperature of the material is T _m (° C.), and the temperatures T _G and T shown on the vertical axis of FIG.
_DR , T _SR and T _R are respectively defined as follows: T _G (° C) = 0.93 T _m (° C.) T _DR (° C.) = 0.5 T _m +280 (° C.) T _SR (° C.) = 0.5 T _m −140 (° C.) T _R (° C.) = 0.5 T _m −340 (° C.) T _G , if it exceeds this, under the conditions of ordinary industrial ingot heating, the crystal grains become coarse or marked. This is the temperature at which field oxidation occurs. T _{G to} T _DR is a region where dynamic recrystallization is possible under normal industrial hot rolling conditions. In this region, new recrystallization nuclei are formed in the grains or at the grain boundaries according to the strain rate during the rolling pass, and grain refinement proceeds. In this region, grain refinement due to static recrystallization between rolling passes described below may also occur. T _{DR to} T _SR are
It is the region where static recrystallization is predominant under normal industrial hot rolling conditions. In this region, after the rolling deformation, new recrystallization nuclei are formed in the grains or in the grain boundaries according to the strain amount accumulated by the rolling deformation, and the refinement of the crystal grains proceeds. That is, static recrystallization and dynamic recrystallization, the controlling factor of the recrystallization progress is the accumulated strain amount in the former, the strain rate in the latter, the recrystallization after the deformation in the former. , The latter is different in that it progresses during deformation. T
_SR through T _R is a region that can occur only recover a normal industrial hot rolling conditions.

Next, as shown in the rolling condition curve of FIG.
Ingot heating temperature: T _H (℃), the hot rolling start temperature:
Specify T _RS (° C.) and hot rolling end temperature: T _RF (° C.), respectively.

According to one aspect of the present invention, as shown in FIG. 1 (a), (1) the ingot is heated under the condition of T _H <T _G , and (2) −200 ≦ T _DR −T _RS ≦ 200 and T _RF > T
_{Under SR} condition, the total reduction ratio from T _RS to T _RF is 70
Perform hot rolling to a value of at least%. Ingot heating temperature: T
_H must be less than or equal to T _G. This is because if it exceeds this, the ingot itself causes coarsening of crystal grains or remarkable grain boundary oxidation. Hot rolling start temperature: T
_RS, as indicated by a curve X and Y, at a temperature between 200 ° C. temperature lower than T _DR from 200 ° C. higher temperature than _{T DR (T DR -200 ≦ T} RS ≦ T DR +200). That is, hot rolling, 2 from T _DR regions T _DR occur dynamic recrystallization can region or static recrystallization within 200 ° C. than is the main
It is possible to start from any of the hot side zones in the range of 00 ° C. End temperature of hot rolling: T _RF is set higher than T _SR . Here, the total reduction rate from T _RS to T _RF needs to be 70% or more. The reason is that if it is less than 70%, a sufficient number of recrystallization nuclei are not formed and crystal grains are not miniaturized.

[0015] Furthermore, according to another aspect of the present invention, further, as shown in FIG. 1 (b), heating the ingot under the conditions of _{(1) T H <T G} , (2) -200 ≦ T _DR −T _RS ≦ 200 and T _SR >
In conditions of _{T RF>} T _R, the total rolling reduction in the range of up to _{T SR} from _{(a) T RS} 70
% Subjected to hot rolling to above, perform warm rolling to total reduction ratio of 5% or more by further (b) in the range from T _SR to T _RF. In the case of FIG. 1 (a),
After hot rolling in the range from T _RS to T _SR , T _SR
The difference is only that warm rolling with a total rolling reduction of 5% or more is added within the range from 1 to T _RF . In warm rolling,
In warm rolling, strain accumulation necessary for recrystallization nucleation can be achieved more effectively, and a finer recrystallized structure can be obtained in the subsequent cold rolling and annealing steps.
In order to obtain the desired effect, it is necessary to set the total rolling reduction to 5% or more.

When cold rolling after hot rolling is difficult or when it is necessary to maintain the homogeneity of the structure after hot rolling, T _DR to T
Annealing can be performed for 10 minutes to 24 hours in the temperature range up to _SR .

After that, cold rolling and annealing are repeated until the crystal grain size after final annealing is less than 10 μm, and then final cold rolling is performed. Cold rolling and annealing conditions can be adopted as long as it is possible to create a fine grain structure having a grain size of less than 10 μm after the final annealing by repeating cold rolling and annealing after hot rolling or warm rolling. One preferable condition is the following condition proposed in JP-A-4-160112. The degree of rolling process before the final annealing is important for ensuring the desired strength of the lead frame material.
It is limited to 0 to 90%. The reason is that the rolling degree is 40
It becomes a duplex grain without obtain desired fine grain stable during final annealing in the case of less than%, whereas, by the texture during final annealing becomes the rolling working ratio greater than 90%
Anisotropy of strength developed, the result of that is that the uniform intensity that desired even if the final cold rolling, stress relief annealing is not obtained. The final annealing condition is also important for ensuring the desired strength of the lead frame material, and is a factor that also greatly affects the etching property and press workability, but especially under the condition that the obtained crystal grain size is 10 μm or less. The reason for carrying out annealing is that the desired high strength can be achieved by reducing the grain size.
In addition to being achieved, good results are obtained in etching property and press workability, and it is effective in realizing a high-accuracy lead frame. On the other hand, if the crystal grain size exceeds 10 μm, these effects can be secured. This is because it will not be possible. The adjustment of the grain size during the final annealing, the annealing temperature及beauty as well known
It intends line depending on the regulation of inter-time. Although the workability in the final rolling has a great influence on the strength of the lead frame material, it is preferable to limit the workability to 40 to 85%. The reason is that when the rolling workability is less than 40%, a remarkable effect for improving strength cannot be obtained, while when it exceeds 85%, the anisotropy of strength becomes remarkable. By performing appropriate strain relief annealing after the final rolling, the Kb value is improved, its anisotropy is also dramatically improved, and bending workability and sealing property are also improved, so that strain relief annealing is performed. . For example, in a continuous annealing furnace in a reducing atmosphere, furnace temperature: 500-9
The above effect can be obtained by heat treatment at 00 ° C. and residence time of the material in the furnace: 10 to 120 seconds.

Thus, it is possible to manufacture an Fe-Ni alloy thin plate for electronic parts having a Vickers hardness of 240 or more and a tensile strength of 800 MPa or more.

By adding an appropriate amount of Co, it is possible to aim at the effect of introducing work-induced martensite, and by adding an appropriate alloying element, solid solution strengthening by these elements or refinement of the crystal grain structure and dislocation substructure can be achieved. Can be expected. Therefore, the Fe-Ni alloy of the present invention means Fe
-Ni-Co system, Fe-Ni-X system (X = Cr, Nb,
Ti, Mo, W, Ta, Cu, V, Zr, Hf) system and Fe-Ni-Co-X (X = same as above) system are included. Co can generally be added in the range of 0.1 to 20% by weight. X can be added in the range of 0.01 to 5% by weight. Since all of these additive elements X have the effect of increasing the strength and the thermal expansion coefficient of the lead frame material, by improving the material strength and increasing the thermal expansion coefficient to approach that of the resin mold, the sealing property is improved. For the purpose of further improving the above, one kind or two or more kinds are contained as necessary. In particular, Co, Cr, Mo, W, V, N
b, Ta, Ti, Zr, and Hf also have an effect of improving the etching property because they form carbides and reduce the amount of solid solution carbon, and the crystal grains are refined by the dispersion of the carbides.
It also brings about an effect of increasing strength and improving bendability. But,
If the total content is less than 0.01%, the desired effect due to the above-mentioned action cannot be obtained. On the other hand, if the total content exceeds 5.0%, the material becomes too hard to be molded. In addition to the deterioration of workability, it becomes difficult to secure an appropriate coefficient of thermal expansion, so the total content of the above components is 0.01.
It is good to be set to 5.0%.

[0020]

[Examples] Table 1 shows the chemical compositions of the test materials A and B.

[0021]

[Table 1]

Melting start temperature of sample A: T _m is 1440
C. Therefore, T _G = 1340 ° C. T _DR = 1000 ° C. T _SR = 580 ° C. T _R = 380 ° C. Melting start temperature of the sample B: T _m is 1436 ° C. Therefore, T _G = 1335 ° C. _DR = 998 ° C. T _SR = 578 ° C. T _R = 378 ° C. Tables 2 and 3 show the test conditions of the test materials A and B, the average crystal grain size after the final annealing, the Vickers hardness and the tensile strength after the final processing step, respectively. In Tables 2 and 3, R ₁ and R ₂ respectively represent the total reduction rate from T _RS to T _RF or T _RS to T _SR and the total reduction rate from T _SR to T _RF . Some of the test materials A and B were annealed at a temperature of 700 ° C. for 0.5 hours after hot rolling.
d _F , H _V and σ _t represent the average crystal grain size after the final annealing, the Vickers hardness and the tensile strength after the final processing step, respectively. In this test, the final cold rolling rate is 70% for any of the test materials.

[0023]

[Table 2]

[0024]

[Table 3]

As is clear from Tables 2 and 3, in the Fe-Ni alloys produced under the conditions of the present invention, the crystal grain size after final annealing is less than 10 μm, Vickers hardness: 240 or more and tensile strength. S: 800 MPa or more, fine particles and high strength are realized.

[0026]

By performing ingot heating and hot rolling under predetermined conditions, further annealing under predetermined conditions when necessary, and then repeating cold rolling under appropriate conditions and subsequent annealing, We have succeeded in achieving more effective strengthening of the Fe-Ni alloy than by only optimizing the conditions of cold rolling and subsequent annealing.

[Brief description of drawings]

FIG. 1 (a) and (b) are schematic views showing aspects of hot rolling according to the present invention.

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Claims (4)

(57) [Claims] 1. T _G , T _DR and T _SR are each T _G (° C.) = 0.9, where T _m (° C.) is the melting start temperature of the material.
3T _m (° C), T _DR (° C) = 0.5T _m +280 (° C)
And T _SR (° C.) = 0.5 T _m −140 (° C.),
When the ingot heating temperature is T _H (° C.), the hot rolling start temperature is T _RS (° C.), and the hot rolling end temperature is T _RF (° C.), (1) T _H <T _G is satisfied. and the ingot heating _{step, (2) -200 ≦ T DR} -T RS ≦ 200 and T _RF
A hot rolling stage in which hot rolling is performed such that the total rolling reduction from T _RS to T _RF is 70% or more, while satisfying the condition of> T _SR ;
(3) After that, cold rolling and annealing are repeated, the grain size after final annealing is set to less than 10 μm, and then a cold rolling step of performing final cold rolling is included.
A method for producing an Fe-Ni alloy thin plate having a Vickers hardness of 40 or more and a tensile strength of 800 MPa or more. 2. The melting start temperature of the material is T _m (° C.), and T _G , T _DR , T _SR and T _R are respectively T _G (° C.) =
0.93 T _m (° C.), T _DR (° C.) = 0.5 T _m +280
(° C.), T _SR (° C.) = 0.5 T _m −140 (° C.) and T
_R (° C.) = 0.5 T _m −340 (° C.), the ingot heating temperature is T _H (° C.), and the hot rolling start temperature is T.
_RS (° C.) and when the hot rolling finishing temperature and _{T RF (℃), (1} ) T H < and T _G becomes charged to the ingot heating phase _{condition, (2) -200 ≦ T DR} -T RS ≦ 200 and T _SR ＞
Hot rolling that satisfies the condition of T _RF > T _R and that the total reduction rate is 70% or more within the range from T _RS to T _SR , and further performs the total reduction within the range from T _SR to T _RF The hot rolling stage in which warm rolling is performed at a rate of 5% or more, and (3) after that, cold rolling and annealing are repeated, and the crystal grain size after final annealing is 10 μm.
Fe having a Vickers hardness of 240 or more and a tensile strength of 800 MPa or more, characterized in that it comprises a cold rolling step of less than, followed by a final cold rolling.
-A method for manufacturing a Ni-based alloy thin plate. 3. After the hot rolling step of (2), T _DR to T _SR
The method according to claim 1 or 2, characterized in that the annealing is carried out for 10 minutes to 24 hours in the temperature range up to. 4. In the cold rolling step of (3), the final annealing is performed after rolling with a workability of 40 to 90%, and the workability of the subsequent cold rolling is adjusted to 40 to 85%. The method according to any one of claims 1 to 3, characterized in that: