JPS6379929A - Copper-nickel-tin alloy for integrated circuit conductor and its production - Google Patents

Abstract

PURPOSE:To obtain required elongation percentage without applying age precipitation treatment and also to obtain high tensile strength and high electrical conductivity while maintaining the above elongation percentage, by subjecting a copper-nickel-tin alloy material in which respective contents are limited to melting, casting, and rolling and also by specifying annealing conditions at the prescribed thickness. CONSTITUTION:The raw material consisting of, by weight, 0.5-3.0% Ni, 0.5-0.9% Sn, 0.01-0.2% P, >0% Mn and/or <=0.35% Si, and the balance copper is melted, cast, and then is subjected to ordinary rolling. At this time, annealing is applied at 360-395 deg.C for 1hr at a thickness capable of providing >=60% draft from the finally required thickness, so that alloy having required mechanical properties and dielectric constant can be manufactured.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a lead frame material for integrated circuit conductors and a method for manufacturing the same, and more specifically, it relates to a lead frame material for integrated circuit conductors and a method for manufacturing the same. The present invention relates to a copper-nickel-tin alloy for integrated circuit conductors, which has excellent plating properties and economic efficiency, and a method for manufacturing the same.

[Technical background of the invention]

Lead frame materials for integrated circuit conductors require alloys that have high tensile strength, high electrical conductivity, and excellent economic efficiency while maintaining a bendable elongation rate (6% or more in practice). . ``However, tensile strength and electrical conductivity are generally contradictory properties, so one of the properties is sacrificed in order to take advantage of the other.Currently, thin bronze (elongation weight %) With the above, tensile strength II
! ky/- degree, electrical conductivity 37%), red copper (elongation coefficient or more, tensile strength 35 to 9/mA, electrical conductivity 37
H), silver copper (tensile strength 2-Okq/mA, conductivity 37% at elongation coefficient or more), silver copper (tensile strength 'Ajkq/rum, at elongation coefficient or more), electrical conductivity) and recently developed iron-added materials,
In addition, alloys containing P, Co, Sn, and Zn (elongation weight of 1000 kg or more, tensile strength of 3!~rOkg/mA, electrical conductivity of 35~20%), etc. are used. In addition, various existing copper alloys have similar characteristics to those of the above-mentioned alloys. In particular, a disadvantage common to each of the above-mentioned alloys is that the materials are expensive.

Generally, alloys are subjected to precipitation aging in order to increase their tensile strength, so the cost of heat treatment cannot be ignored. However, assuming that the heat treatment costs are the same, the cost of raw materials for the elements constituting the alloy becomes the factor that determines economic efficiency.

Of course, there are copper alloys with elements Ti, Zr, Qr, etc., which increase tensile strength and do not reduce electrical conductivity when added in trace amounts. However, in order to add these high melting point, highly oxidizing elements Ti, Zr, and Or, it is necessary to uniformly dissolve them in copper.
This increases the difficulty of the precipitation hardening manufacturing process, which in turn leads to higher manufacturing costs. For these reasons,
Precipitation hardening copper alloys containing Ti, Zr, Or, etc. are not mass-produced and sold.

For the above reasons, phosphorus is currently being used as a lead frame material for integrated circuit conductors, which has relatively high tensile strength but low conductivity when a certain elongation rate (2% or more) is secured. Bronze is widely used.

[Problem that the invention seeks to solve]

However, the phosphor bronze used as a lead frame material for integrated circuit conductors that satisfies the above-mentioned purpose is a copper alloy with a composition consisting of 3 to 3% by weight of Sn, 0.35 to 0.35% by weight, and the balance O. However, there was a problem that it contained a large amount of the expensive Sn element, resulting in high material costs.Therefore, the present invention was made to eliminate the drawbacks of conventional lead frame materials for integrated circuit conductors. One of the objects of the present invention is to provide a copper-nickel-tin alloy for integrated circuit conductors that has high tensile strength and high electrical conductivity while maintaining a bendable elongation rate, and is highly economical. That is.

Another object of the present invention is that the above-mentioned copper-nickel-tin alloy for integrated circuit conductors does not require precipitation aging treatment, and moreover, an elongation rate of 2% or more, which is required in practice, can be easily obtained. The purpose is to provide a manufacturing method that can obtain high tensile strength and high electrical conductivity while ensuring the following.

[Failure to solve the problem]

The inventors of the present invention have repeatedly conducted various experiments in order to eliminate the above-mentioned defects in copper-nickel-tin alloys for integrated circuit conductors, and have found the following.

■ Strengthening of not only copper alloys but also alloys is obtained by precipitation hardening. On the other hand, the conductivity becomes higher as the alloy is diluted with a smaller amount of added elements. However, since the degree of reduction in conductivity due to added elements differs depending on the type of element, it is possible to maintain a certain level of conductivity while maintaining a certain tensile strength.

＠ Also, in order to balance the tensile strength and electrical conductivity, which have contradictory relationships in alloys as mentioned above, the amount of added elements to copper is reduced to reduce the decrease in electrical conductivity, and this also reduces the decrease in electrical conductivity. It is possible to reduce raw material costs.

θ However, this is disadvantageous in terms of increasing mechanical strength. Therefore, the present inventors added Ni and Etn,
It was thought that it would be good if P remained during deoxidation. However, these additive elements are not intended for precipitation hardening, but are aimed at solid solution hardening, and furthermore, are aimed at increasing the degree of work hardening.

As a result of this experiment, Ni 3.0-0. evening weight%,
F3nQ, ri~o, , rwt%, Pθ, 2~0.0/
At a maximum of 0.35% by weight, such as Si, Mn, etc., the tensile strength can be increased to approximately πkq/at an elongation rate of 2% or more by combining with the heat treatment and rolling treatment described below.
It turns out that it is possible to -.

■ Also, the properties of metal materials vary depending on their processing and heat treatment methods. The same is true for copper-nickel-tin alloys,
In order to obtain high tensile strength at an elongation rate of 4% or more, cold rolling is repeated until the required thickness (thickness that allows a working rate of 604 or more) is reached. The material must be annealed for 7 hours (so-called stop annealing) and cold rolled at a temperature of /JO'C for 7 hours, and then annealed for 7 hours at a temperature of /JO'C-230°C to exhibit the desired properties.

This relationship is Ni/, 0 wt%, F3nO, 3 wt%
, p o, θ! As a result of experiments on a copper-nickel-tin alloy having a composition of 5% by weight with the balance being O, the results shown in the following table were obtained.

Table / Generally, when an alloy is annealed at a high temperature, the elongation rate increases, but the tensile strength decreases. However, the copper-nickel-tin alloy constructed as described above is different and is susceptible to work hardening. In addition, the work-hardened material has less decrease in tensile strength due to annealing, and has a tensile strength of several 10 kq/
- I learned that it is about

0 Furthermore, changes in mechanical properties due to processing and annealing are also influenced by composition. According to experimental results, in the case of a copper-nickel-tin alloy having the above-mentioned composition, work hardening is mainly provided by Sn. On the other hand, the elongation rate is mainly obtained by Ni, and as is clear from the characteristic curves ■, ■, ■ and ■, @, O in Fig. 1 showing the relationship between working rate and tensile strength, which will be described later, only N1 Based on the degree of work hardening when added to Cu, it was found that the work hardening of a copper-nickel-tin alloy containing 7% by weight of Ni and further adding Sn was found to be high. The hardening rate is high in the range where the rolling rate is high. Moreover, it was found that this effect can be obtained even when the amount of Sn added is low, and the present invention was completed.

That is, the copper-nickel-tin alloy for integrated circuit conductors according to the present invention has N10. j~3.0% by weight, Sn0, 1-0.
Copper-nickel-tin alloy having a composition of 2% by weight, P O,0/~9,2% by weight, Mn and/or Si in an amount exceeding O but not exceeding 0.35% by weight, and the balance consisting of Cu. It is.

In addition, the method for manufacturing the copper-nickel-tin alloy for integrated circuit conductors described above includes N1Q3~3.0% by weight, 5nO8~O1~02% by weight, PO,0/~02% by weight, and Mn and/or Si. After melting and casting the raw material in which O is added to an extent exceeding 0 and not exceeding 0.35% by weight, and the remainder is O,
From the final required thickness by normal rolling, the thickness is 31.0'C ~ 3. It is characterized by being annealed at a temperature of °C for 1 hour to exhibit the required properties.

In the copper-nickel-tin alloy for integrated circuit conductors of the present invention, if it contains 0.3% by weight or more of Sn, it will be work hardened if the rolling addition rate is 60% or more, similar to when it contains a large amount of Sn. The rate is almost the same, and like traditional phosphor bronze, the
It is not necessary to contain more than % by weight of Sn. Here sn
The lower limit of the amount added is a value that allows a tensile strength of about 60 ky/- to be obtained when the above-mentioned results and processing rate are increased.

Further, the upper limit of the amount of Sn is a value that satisfies both the tensile strength and the electrical conductivity, since the tensile strength can be increased as the amount of 61n increases, but on the other hand, the electrical conductivity decreases. In the coexistence of Ni, P5, Si, and Mn, in order to obtain a conductivity of about 35 coefficient or higher, it is preferable to set the upper limit to the weight percent of SnO.

Further, as for N1, as described above, the elongation rate is increased. Normally, in order to increase the elongation rate by annealing after processing, it must be annealed at a significantly higher temperature. In this case, the tensile strength inevitably decreases. However, according to the experimental results of the present inventors, it is possible to improve the elongation rate of a copper-nickel-tin alloy within a range where the tensile strength does not decrease.

For example, N110% by weight - 8nO,, fM amount% - Po, o
3-wt%-remainder Ou: Ni/, 2 wt%-S
n O2 weight Qi P 0.2% by weight - balance Ou: N
i O,! The annealing temperature (°C), tensile strength (ky/mA), and elongation rate (%) of a copper-nickel-tin alloy with a composition of wt%-EJnO, 3wt%-P0.0/wt%-remainder Cu were measured. According to the results, the second
Curves in the figure ■, ■.

As shown in (2), the elongation rate can be improved within the temperature range where the tensile strength does not decrease. Of course, as mentioned above, this
It is related to the processing and annealing process and the resulting metal structure. The manufacturing process of the present invention results in fine spherical particles with a diameter of about 20 μm, which is essential for obtaining elongation. It is thought that such a structure can also be obtained with other alloy systems.

By including Ni in an amount of at least 1% by weight, the above-mentioned effect becomes remarkable. On the other hand, the upper limit of the amount of N1 added is determined from the relationship between economic efficiency and electrical conductivity. i.e. P, Sn and Si
If N1 exceeds 3.0% by weight in coexistence with Mn, the electrical conductivity will be about 35 coefficients or less, which is an inappropriate value for lead frame materials.

Furthermore, since the middle layer of the constituent elements of N1 is also expensive, it is desirable that it be as low as possible from the viewpoint of raw material cost. Here, we have mentioned that N1 greatly contributes to elongation, but in addition to this, it also contributes to an increase in strength, as shown in the relationship diagram of processing rate (ch) vs. tensile strength (ky/rrU) shown in Figure 1. do.

In addition, the curves ■, ■, ■ in Figure 1 are E3n3,
9wt%-Ni/wt%-Po, 23wt%-remainder Ou
: Etn Q, 7wt%-Ni/wt%-PO,/
Weight %-Remaining Cu: SnO,! Weight %-Ni/weight ratio-PO, OJ weight %-remainder (+u copper-nickel-tin alloy, showing the relationship between processing rate and tensile strength of gold, curve 2).

@, θ, O are each Ni? Weight% - balance Cu:Ni
! Weight% - balance Cu: Ni 2% by weight - balance Ou:
The relationship between the processing rate and the tensile strength of a copper-nickel alloy of N1/wt%-remaining Cu is shown.

As mentioned above, NiO, 6 to 3.0% by weight, Sn0, 3
~O92 wt%, Po, 0/~01.2 wt% and O
A copper-nickel-tin alloy consisting of u can also provide sufficient strength.

However, these copper-nickel-tin alloys contain Si.

When Mn is added, the tensile strength during annealing can be slightly increased, as will be made clear in the examples described later. Si for tensile strength.

The effect of adding Mn can be slightly higher than the effect of just adding Sn.

In the present invention, it has been confirmed that by adding Mn and Si up to 0.35% by weight, the electrical conductivity can be increased to about 3% in coexistence with other elements.

Regarding P, although a Cu-P master alloy is normally used as a deoxidizing agent, it is necessary to leave a trace amount of this.

〔Example〕

Next, typical embodiments of the present invention will be described.

2.4-kg of Ni, Eln, P, Si, Mn, and Cu having the compositions (wt%) shown in each row of the second column of Table 2 below were dissolved in the atmosphere, and this was made into a round bar shape. Or cast into square material, 60o'c or more yoo
After casting at a temperature of 'c', cold rolling was performed to produce plates having a thickness of lxm to IO'mm. Here, cutting and surface grinding were performed and used for various process experiments. In the standard manufacturing method, from the above thickness, cold rolling and annealing (60 o'c>) were repeated/Weijima thickness.

Annealed at 37 joc for 7 hours at /xm thickness, 0
．． It was cold rolled to a thickness of 2.2 mm. The final cold rolling rate is 7!
I am in charge of r. This was slit to a width of 2 Vrm, and the obtained samples were slit into A/, A-2, A3, A-2, A-2, A-2, A-2, A-2, A-3, A-2, A-2, A-2, A-2, A-2, A-2, A-3, A-2, A-2, A-2, A-2, A-3, A-2, A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A-2 A3 sample of different alloy compositions are shown in each row of the second column of Table 2. A4'..., Boiled/2
And so.

Then, each sample A/, A2. A3. ..., J16.
Mechanical properties, electrical conductivity, etc. of /2 were measured for bending workability and hardness as a copper-nickel-tin alloy for integrated circuit conductors.

Tests were conducted for plating properties, etc. The results are shown in Table 2.
Shown in the column. However, the annealing conditions shown in the third column of Table 2 represent the annealing conditions (temperature range and time) when the elongation rate is set at the lowest level in the relationship between annealing temperature and elongation rate shown in FIG. 2 described above.

Table 2 For example, in the alloy sample of Table 2, Boiled 3, the surface roughness of the plate in the indicated state is 0.3! μ, bending radius 0.2ffll
Regarding the bending workability of the R paste O0W bending, there was no cracking in the direction parallel to rolling, but cracking was observed in the direction perpendicular to the rolling direction.

Moreover, the hardness is Hv/Hirof. Furthermore, no problems were observed in terms of plating properties due to Ag plating, and it was confirmed that the material was an excellent lead frame material.

〔Effect of the invention〕

As explained above, the alloy and manufacturing method of the present invention have extremely good properties such as strength of 0 to 10Ky/J, elongation of 2T, and electrical conductivity of 3T to 3F with an economical amount of ingredients. It is a copper alloy. Moreover, these alloy manufacturing methods do not include precipitation hardening treatment, and conductors for integrated circuits can be manufactured economically.

[Brief explanation of the drawing]

Figure 1 is a characteristic curve diagram showing the relationship between processing rate and tensile strength of the copper-nickel-tin alloy according to the present invention and a conventional copper-nickel-tin alloy, and Figure 2 is annealing of the present copper-nickel-tin alloy for integrated circuit conductors. It is a characteristic curve diagram showing the relationship between temperature versus tensile strength and elongation rate. In the figure, ■-Sn 3. Q weight%-Ni/weight%-Po, 2! Characteristic curve of weight %-remaining O, ■...BnO, 7 weight %
- Remaining 7% by weight - P O, / weight % - Characteristic curve of remaining O, ■ ... SnO, weight coefficient - Ni / weight coefficient -
F 6.0 ta weight % - balance O characteristic curve, ■...N
i weight% - characteristic curve of balance O, @...Ni j weight - characteristic curve of balance O, θ...Hi 2% by weight -
Characteristic curve of remainder O, ■...Ni/weight%-remainder Q
Characteristic curve of u, ■M1/, 0 wt%-SnO,! weight%
-P0.0! Characteristic curve of weight %-remaining Cu, ■...N
i /, 2% by weight - Sn O, 2% by weight - P O,
,! Characteristic curve of weight % - remainder O
characteristic curve.

Claims (2)

[Claims] (1) Ni0.5-3.0% by weight, Sn0.5-0.9
% by weight, P0.01 to 0.2% by weight, Mn and/or Si in an amount exceeding 0 and not exceeding 0.35% by weight, and the balance being Cu. Copper nickel tin alloy. (2) Ni0.5-3.0% by weight, Sn0.5-0.9
After melting and casting a raw material containing P0.01 to 0.2 wt%, Mn and/or Si in an amount exceeding 0 and not exceeding 0.35 wt%, and the balance being Cu, ordinary Copper for integrated circuit conductors, which is characterized by being rolled and annealed at a temperature of 360°C to 395°C for 1 hour at a thickness that allows a processing rate of 60% or more from the final required thickness to exhibit the required properties. Method for producing nickel-tin alloy.