JPS62149851A - Electronic parts material and its production - Google Patents

Abstract

PURPOSE:To produce an electronic parts material having good etchability and workability by specifying the crystal grain size of an alloy compounded with iron Ni, and Cr at specific ratios. CONSTITUTION:An ingot of the alloy contg. 25-45wt% Ni, 0.3-10wt% Cr and consisting of the balance iron and unavoidable impurities is manufactured. After the ingot is subjected to plural passes of rolling-annealing treatments, the ingot is subjected to the final cold rolling treatment at >=40% draft. The cold rolled material is subjected to an annealing treatment at 500-1,200 deg.C then to an adjustment rolling treatment at <=30% draft and further preferably to an annealing treatment at about 200-500 deg.C. The electronic parts material having 6-12 crystal grain size specified in JIS-G0551 is thereby obtd. This electronic parts material is preferably formed with >=80% austenite structure and is aggregated with the crystal orientation at (100). Part of Cr is replaceable with Mn and the rate of substn. is specified to about 0.3-7wt% by the total weight of the alloy. Addition of Co up to max. 7wt% is also possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electronic component material, and more particularly to an electronic component material useful as a material for a lead frame of a consumer product, such as a semiconductor device.

[Technical background of the invention and its problems] Consumer products such as semiconductor devices are required to have high output and multiple functions, but they also need to be manufactured with high productivity and low cost. is necessary.

Various manufacturing methods have been developed to meet this requirement, and among them, resin molding is a fairly useful method.

However, this method has the following problems, which need to be solved.

That is, although the above method includes a mounting process and a bonding process between the semiconductor element and the lead wire as essential processes, the problem is related to the lead frame, which is an important component.

In general, lead frames must have low surface oxidation, high tensile strength, sufficient ductility and bending workability, high-temperature properties, such as excellent mechanical strength at temperatures of 250°C or higher, and good wettability with solder. It must have sufficient hardness and weather resistance, as well as good etching properties and excellent workability such as press punching and press bending properties.
Satisfying the following conditions is extremely advantageous in terms of manufacturing, price, and product characteristics.

Because it satisfies these various characteristics relatively well, 42Ni has traditionally been used as a material for lead frames.
-Fe alloys were widely used.

However, in recent years, the number of bins in lead frames has been increasing as seen in flat packages. For this reason,
Lead frames require precise and minute etching. In addition, lead frames with high curvature bending have also appeared in some products. However, the conventional 42Ni-Fe alloy described above cannot meet the above requirements as the number of pins increases.

For this reason, copper alloys, which are soft and have good etching properties, have begun to be frequently used as lead frame materials.However, this material has a thermal expansion coefficient that is not compatible with silicon chips, and is too soft, causing deformation after press forming. It has the disadvantage of being easy to do.

Therefore, materials for electronic components such as lead frames, especially materials for lead frames of flat packages, must have (1) excellent etching properties, and (1) be appropriately soft and have excellent workability during press working, as well as work hardening properties. The following are emerging as major property issues that need to be resolved: low deformation after processing, and low thermal expansion.

Recently, materials have been developed that have low thermal expansion, are easy to etch, are easy to press, and are work-hardened.
Ni-Fe alloys are attracting attention as lead frame materials.

[Object of the Invention] The object of the present invention is to provide a Ni--Fe alloy material and a method for producing the same, which improve the above-mentioned characteristic items (1) to (2) required for electronic components, particularly (1), and (4).

[Summary of the Invention] In the course of intensive research to achieve the above object, the present inventors have considered the above properties, especially the improvement of the etching properties of (D). Holes formed during etching are judged to have irregularly large and small cracks on their inner walls, resulting in so-called irregular "rough holes."Therefore, materials with poor etching properties are not suitable for design. This makes it impossible to provide the fine etching finish required by the standards.

This means that the type and uniformity of the metal structure that makes up the material,
This problem is thought to be caused by the size of the crystal grains, the aggregation of the crystal orientation, etc. Therefore, the present inventors conducted various studies on the influence of each of the above factors on the characteristics required of the lead frame material. At the same time, the search for suitable conditions for the items (1) and (2) was clearly considered and repeated research was conducted, leading to the development of the material of the present invention and its manufacturing method.

That is, the electronic component material of the present invention contains 25 to 45% by weight of Ni and 0.3 to 10% by weight of Cr.
, and the balance is Fe and unavoidable impurities, and the crystal grain size specified by JIS-G0551 is 6 to 1.
It is characterized by being 2.

The manufacturing method includes 25-45i amount% of Ni0, 3-1
oriLffi% amount c7) Step of melting Cr and Fe into an alloy ingot (first step); After subjecting the alloy ingot to rolling-annealing treatment multiple times, final cold rolling treatment is performed at a rolling rate of 40% or more. Step of applying (second step): Step of annealing the cold-rolled material at a temperature of 500 to 1200°C (third step); Step of subjecting the annealed material to adjustment rolling treatment at a rolling rate of 30% or less ( 4th step): It is characterized by consisting of.

In the material of the present invention, if the crystal grain size is less than 6, the grain size is too coarse and etching removal during etching does not proceed sufficiently, resulting in areas that do not open. If it exceeds 12, the grain size is too fine and the inner walls of the holes opened during etching will have many irregular cracks, which will easily result in so-called rough holes. Practically speaking, it is preferably 8 to 12, and particularly preferably 9 to 11.

This crystal grain size is largely determined by the above-described second step and third step, especially the temperature conditions of the third step.

Regarding the etching properties of the material, if the total structure of the material is a mixture of ferrite, martensite, austenite, etc., the etching speed of each structure will be different, so etching will not be smooth. There is a possibility that phenomena such as hole clogging may occur without progressing. Therefore, it is generally preferable that the structure be a single structure, but if it is difficult to do so, there is no practical disadvantage as long as the structure contains 80% or more of austenite.

Furthermore, in the material of the present invention, its crystal orientation is (100
) is preferable, because when etching the material, the inner wall surface of the hole formed becomes very smooth without being rough as in the conventional case, making it suitable for fine WL etching. Usually, it is preferable that the degree of aggregation to (100) is 40% or more. This gathering in crystal orientation can be adjusted by the rolling rate in the second step described above.

In the alloy of the present invention, Ni is set in a range of 25 to 45% by weight. When the amount of Ni is out of the above range, the thermal expansion coefficient of the alloy becomes large, and the object of the present invention of low thermal expansion, specifically, a thermal expansion coefficient of 100 x 1 O-7/°C or less, cannot be achieved. In addition, the amount of Ni increases, specifically 5
If it exceeds 0% by weight, the 0.2% proof stress of the material will increase and its workability will be significantly reduced. Furthermore, when N1fit increases, many rough holes occur during etching, making fine etching difficult, or the amount of Ni dissolved from the material in the etching solution increases, causing the etching solution to denature and reduce its etching speed. Phenomena emerge. Preferably it is 35-45%.

Cr I-) Hu M ±n Th top surface 1-17
After etching the frame and making it into a flat mask with many holes,
In addition, it exhibits important effects during the heat treatment during bonding or the heat treatment for curing the epoxy resin for sealing.

Its content is set in the range of 0.3 to 10% by weight.

In other words, in general, when Cr is added to Fe-Ni alloy and subjected to only hard rolling treatment without annealing, the strength of the material increases by increasing the yield strength by 0.2% at room temperature, but however, during processing. The material remains as a material in which it is difficult to maintain the processing curvature of the leads of the lead frame, that is, the material does not have improved processability. However, as described below, when this material is annealed as described below,
Compared to a Fe-Ni alloy without the addition of Cr, its 0.2% yield strength is significantly reduced and its workability is improved.

For example, Ni-Fe alloy (A) with 6% Cr added
The figure shows the increase in the temperature of 42Ni-Fe alloy (B') without Cr addition by +muO-2% 1-11%. As is clear from the figure, the 0.2% proof stress of Alloy A (material of the present invention) is large at room temperature, but becomes smaller at an annealing temperature of 300° C., contrary to that of Alloy B (conventional material). In other words, annealing improves workability.

However, if the amount of Cr added is less than 0.3% by weight, the above effects will not be exhibited, and if it is more than 10% by weight, the thermal expansion coefficient will be 100X10-'/'0 or more, resulting in the above-mentioned properties. ■ becomes unsatisfied. For this reason, and also taking into consideration etching properties, low chromium in waste liquid, and low thermal expansion, the Cr content is preferably 1 to 4% by weight.

Mn is a component that exhibits the same effects as Cr. Therefore, in the material of the present invention, a part of Cr can be replaced with Mn, and the total amount of Cr and Mn is 0.
It is sufficient if the content is 3 to 10% by weight. Of course, even Mn alone is effective. Usually, the substitution amount is 0.3 to 7% by weight based on the entire alloy, and if Mn is included in an amount exceeding 7% by weight, the coefficient of thermal expansion becomes large.

Furthermore, when Co is added, the etching property is improved.
It is useful because it produces effects such as a reduction in the coefficient of thermal expansion. At this time, the amount of Co added is at most 7% by weight, preferably 1.0 to 6.0% by weight. This Co
If the amount is too large, the 0.2% proof stress will increase and workability will deteriorate.

The alloy material of the present invention can be manufactured through the following steps.

The first step is a step of melting a predetermined amount of each of the above-mentioned components and preparing an alloy ingot having a predetermined composition from the melt. This may be done by applying a commonly used vacuum melting method or by an electroslag melting method.

The second step is a step of subjecting the obtained alloy ingot to a rolling treatment. What is important in this process is that the final rolling is cold rolling, and the rolling reduction during cold rolling is 40% or more. This step basically adjusts the degree of aggregation of crystal orientations on the (ioo) plane. When the rolling ratio is less than 40%, the input machining energy is small, so it is difficult to orient the crystal orientation in the ingot to the (100) plane, and furthermore, it is difficult to orient the crystal orientation in the ingot to the (100) plane. The recrystallized grains that grow in the step) do not have the desired size, and the crystal grain size becomes small.

However, when processed at an extremely high rolling rate, phenomena such as @ cracks occur during the processing process due to the accumulation of added processing strain. Preferably it is 80% or more.

The third step is a step in which the cold-rolled material obtained in the second step is annealed to achieve a predetermined grain size and at the same time a 0.2% reduction in proof stress.

The annealing temperature is 500-1200°C. temperature is 500
If the temperature is less than 'C, the above-mentioned annealing effect will not be sufficiently exhibited, and if the temperature exceeds 1200°C, the crystal grain size will become large and etching properties will deteriorate. Preferably 75
The temperature is 0 to 1100°C. ``In the fourth step, since the annealed material obtained in the third step is usually thermally deformed, this thermal deformation is corrected and the material is rolled into a flat plate. The rolling ratio at this time is controlled to 30% or less.

This is because if the rolling rate is greater than 30%, the already formed state of aggregation of crystal orientations on the (ioo) plane will be destroyed. Preferably it is 20% or less.

In addition, in this process, processing distortion during rolling is accumulated in the plate material, and this distortion may cause problems such as dimensional deformation in the subsequent lead frame manufacturing processes, so after the adjustment rolling process, an additional 800 Temperature below ℃, preferably 200 ~
It is effective to perform annealing treatment at 500°C.

[Examples of the invention] Example I Ni 41% by weight, Cr 4% by weight, CO as an incidental component, 005% hair volume, 5iO0O1 tons: I3X%, P
An alloy ingot containing o and ooi weight percent of S and S, respectively, and the balance being Fe, was prepared by a vacuum melting method.

After repeatedly hot-rolling this ingot, it is washed resistant to primary and secondary
Next, it was cold rolled. The rolling ratio during this rolling was 80%.

Next, the rolled material was put into an annealing furnace and heated to 1X10'4 Torr.
After annealing at 800'C, adjustment rolling was performed at a rolling reduction of 10%. Finally, it was annealed at 500°C to correct thermal deformation.

This plate material has a crystal grain size of 7. Degree of aggregation of crystal orientation on (100) plane 6
0%, the existence ratio of austenite structure was 95%, and the coefficient of thermal expansion was 60 x 10'/''C (20 to 100°C).

A photoresist is applied to both surfaces of the obtained plate material, and after drying, a film with a reference frame pattern formed thereon is adhered, the photoresist is exposed and developed, and the unexposed portions of the 2-odresist are dissolved and removed. did. Then, after hardening the remaining photoresist by burning,
A lead frame was manufactured by etching with a 20% ferric chloride solution and then removing the remaining resist with hot alkali. The width of each lead is 1mm, the spacing between each lead is 0
．． It was 5 mm. When the sides of each lead were observed under a microscope, no rough holes were found.

This lead frame was plated with copper to a thickness of 1ooo, and then further plated with silver of 2p and m to the entire surface. Next, a silicon chip was bonded using silver paste, and a gold wire was further bonded at a temperature of 150 to 300°C, and then the whole was sealed with epoxy resin and cured at 150°C. Finally, when each lead was bent using a predetermined press machine, all the leads were processed according to the design standards, and no deformation was observed after processing, and press workability was good.

Example 2 The composition of the alloy ingot was 36% by weight of Ni, Cr
3% by weight, CO, 05% by weight, 5tO902% by weight,
A plate material of the present invention was prepared in the same manner as in Example 1, except that p and s were both 0.001% by weight, and the remainder was Fe.

The grain size of this plate material is 10, the degree of aggregation of crystal orientation on the (io, o) plane is 45%, and the abundance ratio of austenite structure is 8.
5%, thermal expansion coefficient 32X10'/'C! (20-100
℃).

A lead frame was manufactured using this plate material in the same manner as in Example 1. No springback was allowed for each lead.

Example 3 The composition of the alloy ingot was 36 mm% Ni, Cr
8% by weight, CO, 05% by weight, 5iO902% by weight,
Both P and S were 0.001% by weight, and the balance was Fe. As in Example 1, melting and final rolling were performed at 90%, annealing at 1000°C, adjustment rolling at 5%, and strain relief annealing at 350°C.

The grain size of this plate is 9. The degree of aggregation of crystal orientation on the (100) plane is 80%, the abundance ratio of austenite H[1M is 90%
%, thermal expansion coefficient 70XIO-'/'0 (20~ioo℃
)Met.

A lead frame was manufactured using this plate material in the same manner as in Example 1. No springback was allowed for each lead.

Example 4 The composition of the alloy ingot is 30% by weight of Ni.

Cr 2% by weight, 005% by weight, CO, 05% by weight,
SiO, 02% by weight, p and s are both 0.001
A plate material of the present invention was prepared in the same manner as in Example 1, except that the weight percent and the balance were Fe.

The grain size of this plate is 9. Aggregation degree of crystal orientation on (100) plane is 60%, abundance ratio of austenite structure is 90%
, thermal expansion coefficient 25XIO-'/'C (20-100℃)
Met.

A lead frame was manufactured using this plate material in the same manner as in Example 1. No springback was allowed for each lead.

The plate material containing Co is a material with low thermal expansion as shown by the value of the thermal expansion coefficient described above. However, generally 0.2% of that
The yield strength is higher by about 2 to 5 kg/mm' than in the case where no CO is added, and the workability is deteriorated. Therefore, in the present invention, by adding Cr at the same time as Co, it is possible to lower the 0.2% yield strength without impeding low thermal expansion.

Example 5 The composition of the alloy ingot is N [36% by weight.

Cr 1% by weight, Mn 1% by weight, CO, 05% by weight,
Si O, 02% by weight, P and S are all o, oot
A plate material of the present invention was prepared in the same manner as in Example 1, except that the weight percent and the balance were Fe.

The crystal grain size of this plate material is to, the degree of aggregation of crystal orientation on the (ioo) plane is 65%, and the abundance ratio of austenite structure is 90%.
%, thermal expansion coefficient 25XlO-'/'0 (20-100℃
)Met.

A lead frame was manufactured using this plate material in the same manner as in Example 1. No springback was allowed for each lead.

[Effects of the Invention] As is clear from the above explanation, the electronic component materials of the present invention
1 is a material that has low thermal expansion with a thermal expansion coefficient of 120X10-'/'C or less, and has a small thermal expansion difference with silicon chips>), and has good etching properties and can perform fine etching. Furthermore, it has a small 0.2% proof stress, is highly workable, and does not cause springback, so it has extremely great industrial value as a material for lead frames.

[Brief explanation of drawings]

The figure is a diagram showing the relationship between annealing temperature and 0.2% proof stress of a material obtained by adding Cr to a Ni-Fe alloy.

Claims (7)

[Claims] (1) Nickel 25-45% by weight, chromium 0.3-10
% by weight, and the balance consists of iron and unavoidable impurities, and the crystal grain size specified in JIS-G0551 is 6.
An electronic component material characterized in that the number is 12. (2) The electronic component material according to claim 1, wherein a part of chromium is replaced with manganese. (3) The electronic component material according to claim 1, further containing at most 7% by weight of cobalt. (4) The electronic component material according to claim 1, in which 80% or more of the austenite structure is formed and the crystal orientation is (100). (5) Process of melting nickel in an amount of 25 to 45% by weight, chromium and iron in an amount of 0.3 to 10% by weight to form an alloy ingot; After subjecting the alloy ingot to multiple rolling-annealing treatments, rolling A step of subjecting the cold-rolled material to a final cold rolling treatment at a rolling rate of 40% or more; A step of annealing the cold-rolled material at a temperature of 500 to 1200°C; A step of subjecting the annealed material to an adjustment rolling treatment at a rolling rate of 30% or less; A method for manufacturing an electronic component material, characterized in that: (6) The method according to claim 5, wherein the rolling reduction in the final cold rolling treatment is 80% or more. (7) The method according to claim 5, wherein the adjustment rolling treatment is a treatment in which strain relief annealing is performed at a temperature of 800° C. or lower after the rolling treatment.