JPS5844737B2 - Manufacturing method of conductor alloy for integrated circuits - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a conductor alloy for integrated circuits that has high strength and high conductivity and is highly economical.

Various types of copper alloys have been developed for a long time, and recently there has been a demand for copper alloys with high strength and high conductivity as conductors for integrated circuits.

In copper alloys, strength and conductivity have a contradictory relationship;
For example, there are almost no copper alloys that have a tensile strength of about 40 kg/mm or more, a conductivity of about 35% or more, and are economically superior.

Therefore, phosphor bronze (tensile strength 45 kg/mm at elongation factor 5 or more, electrical conductivity 15 factor or more), red bronze (same as above 3
5kg/m4.37), beryllium copper (same as above 46-8
01y/m4.30 or less), silver bronze (same), 45kg
/m4 85%) or copper with iron (other than P Co S
(Including n, Zn, etc.)
(35-50 kg/md, 40-60%) etc.

Various other copper alloys also have many problems with their economic efficiency when considering the composition as well as heat treatment operations such as processing and aging precipitation treatment.

Recently, various copper alloys including Cu-MnFe alloy have been proposed as low resistance temperature gradient conductive materials.

(Special Publication No. 5), -41968 Publication, Special Publication No. 51-41
969, Japanese Patent Publication No. 51-41970, Japanese Patent Publication No. 52-13163, and Japanese Patent Application No. 52-155090
(Refer to specification) This low resistance temperature gradient conductive material has the characteristic that the increase in conductor resistance that increases with temperature rise is small, and this is one of the desirable properties as a material for lead frames for integrated circuits. However, their purpose of use is different, and they do not necessarily have high strength or high conductivity.

The present invention was made in view of the current situation, and
The purpose is to solve the problems of the prior art and to provide a method for manufacturing a conductor alloy for integrated circuits that has high strength, high conductivity, and is economical.

To summarize the present invention, the method for manufacturing the conductive alloy for integrated circuits of the present invention includes a) 0.8 to 5 weight of Cr, 1 to 9 weight of Fe, or 0.8 to 5 weight of Cr, or 0.8 to 9 weight of Fe, or 0.8 to 5 weight of Cr, or 0.8 to 9 weight of Fe, based on the weight of the entire alloy. (b) at least one element selected from the group consisting of Mn, Sn, Si, and sb with a weight ratio of 0.1 to 0.5; (c) the remainder; The method is characterized in that a copper alloy material containing Cu is melted, rapidly cooled and cast, then hot worked at a temperature of 600° C. or lower, and then slowly cooled.

As a result of various studies aimed at obtaining a metal structure similar to that of a composite material of copper alloys, the present inventors have found that an alloy system having eutectic and peritectic reactions has a high strength due to the fine dispersion effect. Cr or Fe in an amount within a specific range (composition range on both sides of the eutectic point or peritectic point) and Co
(Composition range lower than the peritectic point (5.1 to 5.5% by weight))
It has been confirmed that the above objective can be achieved by containing.

In this case, it is also known that the presence of the finely dispersed material generally has little to do with electrical conductivity.

(The above-mentioned Japanese Patent Publication No. 51-41968 - Special Publication No. 51-4
(Refer to 1970 publication) It is the elements dissolved in Cu that affect the conductivity, and this causes scattering of electrons.

C is an additive element that forms two phases in the alloy in the present invention.
r, Fe and Co are C in an equilibrium state below 600°C.
Almost no U solid solution is formed, and therefore the alloy in the present invention basically has a conductivity approximately equal to that of Cu.

The alloy in the present invention contains a small amount of at least one element selected from the group consisting of Mn, Sn, Si, and sb.

In addition to strengthening the base during hot working, these elements have the effect of increasing the degree of compositional supercooling and promoting grain refinement, but since they are elements that form a solid solution with Cu, the amount of addition is must be reduced.

Here, P, Be. Although Ti, Zr, and the like have similar effects, it has been found that they have a large adverse effect on electrical conductivity.

On the other hand, the stability of the plating film, which is an important characteristic for lead frames for integrated circuits, is greatly affected by the dispersion material (elements other than Cu) of the base (Cu).

According to the results of experiments, in a Cu alloy containing Cr with poor plating properties, when the particle size of the dispersion material and the plating film thickness are approximately equal, the film cannot cover the dispersion material.

Therefore, there is a proportional relationship between the increase in strength due to the dispersion material and the stability of the plated film, and by reducing the size of the dispersion material, it is possible to simultaneously achieve high strength and stability of the plating film.

The composition of the alloy in the present invention is as described above,
In this composition, Cr5φ, Fe9% and Co4%
If it exceeds 40 kg, the dispersed particles will become coarse and the tensile strength will be about 40 kg.
/m4 or more, it is not possible to obtain a dispersed particle state that would result in an alloy having 2.

In particular, in the case of Co, a component amount greater than this becomes uneconomical.

Further, if the content of Cr008, Fe1%, and CoO is less than 5%, the volume fraction of the dispersed particles is low and good tensile strength cannot be obtained.

Furthermore, Mn, Sn, Si, and sb form a solid solution as described above, and if their content exceeds 0.5%, the electrical conductivity will be 35% or less, while if it is 0.1% or less, the conductivity will decrease to the ground. The degree of reinforcement is low and the susceptibility to cracking is high, especially in hot conditions.

In producing the alloy of the present invention, an alloy material having the above composition is first rapidly cooled and cast in order to refine the eutectic or peritectic structure.

As a result, crystal grains are refined, and a fine mixed phase of eutectic and peritectic structures is obtained.

Specifically, this is accomplished at a rapid cooling rate that casts the mold from the normal melting temperature into molds having a diameter of 25 mm or less.

The obtained ingots are processed into plates, bars, wires, etc.
The hot working in the present invention is carried out at a temperature of 600°C or lower to reduce the presence of solid solution from the beginning of the working.

At 600°C, Cr and Fe are 0.05 in equilibrium
%, and Co is dissolved in solid solution in an amount of about 0.5% or less.

Therefore, processing below this temperature will not cause further solid solution,
In addition, a ten analysis is performed.

At temperatures above this temperature, even if slow cooling is performed, re-solid solution of the added elements is unavoidable, the degree of coarsening of the structure increases, and furthermore, the degree of work hardening is affected and the tensile strength is This will reduce the quality.

In addition, hot working at temperatures below 600°C reaches a high concentration range of Cr, Fe, and Co, and develops a fine fiber structure for the eutectic and peritectic alloys of the present invention, which are generally considered difficult to process. This also has the effect of facilitating subsequent cold working.

After processing, slow cooling is performed to avoid solid solution formation.
Moreover, the degree of hardness reduction can be reduced, and the aging precipitation treatment step can be omitted.

The thickness of the plate used as a lead frame is approximately 0°25
In order to reach this final thickness, conventional alloys undergo hot working at a temperature of 600'C or higher and normal working, followed by solution treatment at an appropriate thickness. and aging precipitation treatment are performed respectively.

In addition, the cost of producing a thin plate varies greatly depending on such heat treatment conditions and whether or not there is a subsequent interruption of the process.

Since the general selection criteria in the industry is that it is more advantageous to be economical with slightly better properties, the present invention provides an alloy that is easy to process and has excellent properties. It has advantages that are unparalleled anywhere else.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited to these in any way.

Example 1 With a total weight of 1.2 kg, (A) Cr 1.3 weight ratio, Mn 0.
5% by weight, Cu balance, (B) Cr 1.5% by weight, Mn
, Sb each 0.3% by weight, Cu balance, (C)Cr 1.2
weight bun, Mn.

si@o, 2 weight φ, Cu remainder, and (D) Cr 1.
Electrolytic copper plate and copper chromium, copper manganese, copper tin,
Four weighed alloy materials of copper-silicon and copper-antimony master alloys were melted in a Tammann furnace in an argon stream.

These were cast into a 25 mm t25 mold and immediately poured into water after solidification.

Each obtained ingot was divided into two parts and dried into plates and wires to prepare measurement samples.

For hot working, forging and swaging were performed at 600°C to form a 10 mm thick plate and a 10 mm thick bar.

Then, at the same temperature, it was rolled for 1.25 m using rolls and grooved rolls.
A 1 ton plate and a 4 mm square rod were used.

During this time, the heating and holding time was set to 2 minutes per 1 mrn of thickness and diameter, and after processing, the sample was pulled out in front of the furnace and slowly cooled (approximately .degree. C./min.).

These were finally cold worked into 0.25i1 plates and 1mmQ5 wires.

The mechanical properties and electrical conductivity of these alloys were determined by the annealing temperature (15
~21 minutes in vacuum).

The Vickers hardness was measured for the plate, and the other properties were measured for the wire.

The results obtained are shown in FIG.

That is, FIG. 1 is a graph showing the relationship between the annealing temperature and each property of the alloy of this example, where a is the elongation rate, b is the tensile strength, C is the Vickers hardness, and d is the electrical conductivity. , and curves A, B, C, and D respectively represent the case of an alloy having the composition described at the beginning of this example.

Moreover, the starting point of each curve is the value as it is after processing and slow cooling.

As is clear from the graph in FIG. 1, the alloy of this example has good properties with an elongation rate of 5% or more.

Example 2 The composition of the alloy material was (E)Co 1.0% by weight, Mn0.
3% by weight, Cu balance, (F)Fe 5.0% by weight,
Si 0.3% by weight, Cu remainder, (G)Fe 1.5% by weight, Si 0.3% by weight, Cu remainder and (F()Co
Each alloy material was hot worked into a plate by the same operation as in Example 1 except that the weight φ was 4.0%, Mn was 0.3% by weight, and Cu remained.

The degree of work hardening when slowly cooled (5°C/sec) and rapidly cooled (in water, 200°C/sec), and the decrease in hardness when annealed were investigated.

The results obtained are shown in FIG.

That is, FIG. 2 is a graph showing the relationship between the working rate, annealing temperature, and Vickers hardness of the alloy of this example, where the solid line shows the case of slow cooling, the dotted line shows the case of rapid cooling, and the curve E
.

F, G and H respectively indicate the case of an alloy having the composition described at the beginning of this example.

Further, the starting point of each curve is the value after hot rolling and subsequent slow cooling or rapid cooling.

As is clear from the graph of FIG. 2, the hardness is higher when slow cooling is performed according to the present invention than when rapid cooling is performed.

In addition, in the composition of the alloy of the present invention, unlike the case of Fe addition, the amount of Co added is in a range smaller than the peritectic point (5.1 to 5.5% by weight). It can be seen from Figure 2 that this is due to the low degree of .

Example 3 Using the alloy compositions shown in Table 1 below, 14 types of alloys were prepared by performing the melting and processing operations shown in Example 1, and their properties were investigated.

The results obtained are shown in Tables 1 and 2 below.

Table 1 shows the tensile strength, electrical conductivity and temperature coefficient of resistance at the lowest five elongation rates.

Furthermore, Table 2 shows the plating properties and W bendability (as rolled samples) of five types selected from Table 1 with typical compositions.

Note that cracks occur in W bendability when the processing rate is approximately 80%, but this can be improved by reducing the processing rate.

From Tables 1 and 2, it can be seen that the alloy according to the present invention has high strength and high electrical conductivity, and also has general performance in terms of plating properties and the like.

As explained above, according to the present invention, it is possible to provide a method for manufacturing a conductor alloy for integrated circuits that has high strength and high conductivity and is excellent in economic efficiency.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the annealing temperature, mechanical properties, and electrical conductivity of the alloy of Example 1, and Figure 2 is a graph showing the relationship between the working rate, annealing temperature, and Vickers hardness of the alloy of Example 2. This is a graph. In a, b, c and d of Figure 1, 1 as shown in d.
As shown in Figure 1, a, b, c, and d, A (solid line) is 1.3Cr O, 5Mn-Cu, B
(Dotted line) is 1.5Cr-0,3Mn-0,3Sb-Cu
, C (broken line) is 1.2Cr-0,2Mn-0,2S
i-Cu, D (dotted chain line) is 1.0Cr-0,2Mn
The case of -0,28n-Cu is shown. (The same applies hereinafter.) Also, in Figure 2, E (- and...)
is 1.0Co-0,3Mn-Cu, F (-○ and...○...) is 5.0Fe-0,3S i -Cu
, G (-mouth and...mouth...) is 1.5Fe-
0,3S i Cu , H (X and -X-) is 4.
The case of OCo-0,3Mn-Cu is shown.

Claims (1)

[Claims] 1. Based on the weight of the entire alloy, a) 0.8 to 5 weight of Cr, 1 to 9 weight of Fe, or 0.5 to 4 weight of Co
(b) Mn with a weight ratio of 0.1 to 0.5
. A copper alloy material containing at least one element selected from the group consisting of Sn, Si and sb and (c) the remainder Cu is melted, and after rapid cooling casting, hot working at a temperature of 600 ° C. or less, A method for producing a conductor alloy for integrated circuits, which is then slowly cooled.