JPH0768594B2 - Copper alloys for electrical and electronic parts that are resistant to migration and have excellent hot workability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a migration-resistant copper alloy for electric and electronic parts having excellent hot workability (specifically, copper for semiconductor elements / integrated circuits and terminals / connectors). Alloy).

[Prior Art] Conventionally, Cu-
The iron-containing copper alloy composed of 2.3% Fe-0.03% P-1.13% Zn is known as a high-strength copper alloy material for electric / electronic parts, which has excellent conductivity and heat resistance.

The above-mentioned iron-containing copper alloy contains Fe at the normal temperature or above, which is the solid solubility limit of Fe in Cu or more. Therefore, crystallized and precipitated iron is present in the iron-containing copper alloy ingot produced by continuous casting or semi-continuous casting. When hot working this copper alloy ingot containing iron, averaging treatment for 2 to 3 hours at a temperature of 930 to 980 ° C. as a heat treatment before hot working in order to form a solid solution of crystallized and precipitated iron Need.

Further, the iron-containing same alloy ingot has a brittle region at 500 to 700 ° C., and the high temperature elongation in this temperature region is 6% or less.

Therefore, if homogenization is not performed during hot working, there is a problem that hot cracking tends to occur if the ingot with residual stress of 10 Kgf / mm ² or more is kept in the brittle zone for 30 minutes or more. It was

Furthermore, with the need for lighter, thinner, shorter, and smaller electric and electronic parts in recent years, for example, the integrated circuit resistors have an increased number of electrodes and the need for high-density mounting on a printed circuit board. Inch (2.54mm) to 1/20 inch (1.27m
m) and 1/30 inch (0.847 mm), and the pitch between terminals and connectors is correspondingly reduced.

As described above, when the pitch between the electrodes of the electric / electronic component becomes small, the dew condensation of moisture or the intrusion of moisture causes copper ions to elute in the portion where the moisture between the electrodes adheres, and the copper ions are reduced at the potential between the electrodes. By the repetition of the reduction, a migration phenomenon of Cu occurs, and a short circuit between electrodes is likely to occur.

That is, in the conventional copper alloy for electric / electronic parts, the migration phenomenon of Cu easily occurs and there is a problem of short circuit between electrodes.

[Problems to be Solved by the Invention] As described above, the iron-containing copper alloy composed of Cu-2.3% Fe-0.03P-0.13% Zn is in the ingot state in the middle and high temperature range around 600 ° C. Since the high temperature elongation is as low as 6% or less, a homogenizing treatment at a temperature of 930 to 980 ° C. for several hours is required as a heat treatment before hot working.

The present invention provides the Cu-2.3% Fe-0.03% P-0.1 described above.
Solves the problem that a copper alloy containing iron consisting of 3% Zn tends to cause intergranular cracks during heating during hot working or during hot working, and further, electrical and electronic parts made from the copper alloy. It was made in order to solve the problem of short circuit caused by the migration phenomenon of copper that accompanies higher density.

[Means for Solving the Problems] The present invention has been made based on the above circumstances, and in an alloy for migration-resistant electric / electronic parts excellent in hot workability, Fe: 1.5 to 3.0%, P: 0.001-0.1%, Zn: 1.
0 to 5.0%, Mg: 0.001 to 0.01% (0.01% is not included) and Cr, T
The gist is that 0.001 to 0.01% (not including 0.1%) of at least one of i and Zr is contained, and the balance is Cu and inevitable impurities.

[Function] The migration-resistant copper alloy for electric / electronic parts having excellent hot workability according to the present invention will be described in detail below.

Generally, in continuous casting or semi-continuous casting of a copper alloy or the like, the portion of the ingot excluding the surface layer portion of several mm is gradually cooled and solidified.

In addition, Fe in Cu-Fe alloys at a temperature of 550 ° C or less
The solid solubility limit of is less than 0.15%.

Therefore, in the iron-containing alloy composed of Cu-2.3% Fe-0.03% P-0.13% Zn, 2.15% or more of Fe is precipitated in the grain boundaries / grains. In particular, when a large amount of Fe precipitates at the grain boundaries,
Slip of grain boundaries at high temperatures is less likely to occur, the high temperature strength of grain boundaries is significantly deteriorated, and this causes hot cracking. Again 60
In the middle and high temperature range around 0 ° C, the high temperature elongation is 6% or less, which indicates brittleness.

The present invention suppresses the precipitation of Fe in the crystal grain boundaries by the addition of alloying elements in the copper alloy, improves the medium temperature high temperature strength of the grain boundaries, improves the medium temperature high temperature brittleness, and suppresses the formation of migration of electric / electronic components, The present invention relates to a migration-resistant copper alloy having excellent hot workability, and the reasons for limiting each additive element and the action thereof will be described below.

(Mg) Mg: 0.001 to 0.1% (0.01% is not included).

Mg is an essential element that fixes S mixed in from the raw material, furnace material or atmosphere in the matrix in the form of stable conversion to Mg and improves hot workability. If the content is less than 0.001% There is no above effect, and S moves in the grain boundary and advises the grain boundary cracking. If the Mg content is 0.01% or more, a eutectic with a melting point of 722 ° C called Cu + MgCu ₂ is generated inside the ingot, making it impossible to heat to the hot working temperature of 850-950 ° C. Oxide is often entrained on the surface of the steel and a sound ingot cannot be obtained. Therefore, the Mg content is 0.001
~ 0.01% (not including 0.01%).

(Cr, Ti, Zr) Cr, Ti, Zr: Any one or more of 0.001 to 0.
Contains 01% (0.01% is not included).

If the content of any one of Cr, Ti, and Zr is less than 0.001%, the effect of suppressing hot cracking cannot be obtained, and if the content of 0.01% or more is contained, the molten metal is easily oxidized and a good ingot cannot be obtained. . Therefore, any one or more of Cr, Ti, and Zr: 0.001 to 0.
It is necessary to contain 01% (0.01% is not included).

(Zn) Zn: 1.0 to 5.0% Zn is used to suppress the formation of Cu migration and prevent leakage current when water enters or dew between the electric and electronic parts to which voltage is applied. It is an essential element.

If the Zn content is less than 1.0%, the effect of suppressing migration cannot be obtained, and if the Zn content exceeds 5.0%, the electrical conductivity decreases and stress corrosion cracking tends to occur. Therefore, the Zn content is 1.0 to 5.0.

(P) P: 0.001 to 0.1% If the content of P is less than 0.001%, the deoxidizing effect in the molten metal cannot be obtained, and if it exceeds 0.1%, the hot workability is deteriorated and the conductivity is lowered. Come here. Therefore, the P content must be 0.001 to 0.1%.

(Fe) Fe: 1.5-3.0% Fe contributes to the strength improvement of the material, but its content is 1.5%.
If less than 3.0%, the desired high strength cannot be obtained, and if the content exceeds 3.0%, the conductivity decreases and the crystallized Fe becomes huge, resulting in deterioration of solderability and blistering of Au, Ag plating, etc. It is easy for problems to occur. Therefore, the Fe content needs to be 1.5 to 3.0%.

[Examples] Examples of the copper alloy for electric / electronic parts excellent in hot workability of the present invention will be described below.

A copper alloy having the composition shown in Table 1 was melted in an electric furnace under an atmosphere width under a charcoal coating, and an ingot having a thickness of 50 mm, a width of 80 mm and a length of 180 mm was melted.

Each ingot produced by the above process was cut, and ASTM E8 with a thickness of 6 mm was cut.
A high temperature tensile test specimen of 40 mm thick, a width of 80 mm and a thickness of 180 mm and a test specimen for evaluation of medium-temperature brittleness characteristics of a thickness of 5 mm, a width of 20 mm and a length of 150 mm were prepared.

The high temperature tensile test conditions are 600 ℃, 700 ℃, 800 ℃ and 95 ℃.
The temperature was 0 ° C. and the tensile speed was 2 mm / min.

The hot rolling conditions were such that the rolling start temperature was 950 ° C., the rolling reduction in each pass was significantly 25%, and rolling was performed in three passes, and the rolling end temperature was 650 ° C. or higher and the thickness was 15 mm.

The medium-high temperature brittleness evaluation test is 10 Kgf / mm ^{2 with} three-point support bending.
Stress, and hold for 1 hour at 600 ℃ in a vacuum furnace,
After cooling, the inner surface was bent at a bending radius of 30 mm and bent 90 degrees at room temperature to check for cracks.

Further, for the migration resistance test, a part of each of the ingots was heated at 950 ° C. for 1 hour and then hot-rolled to form a plate material having a thickness of 15 mm, which was rapidly cooled in water.

The oxide case on the surface of the hot-rolled material was removed with 20 vol% sulfuric acid water, and then cold-rolled and annealed at 500 ° C. × 2 hr to produce a rolled material having a thickness of 0.32 mm.

From the above cold rolled material, thickness 0.32mm, width 3.0mm, length 80m
A test piece of m was prepared.

1 and 2 show a test device for measuring leakage current using the test piece. 1 and 2, 1a and 1b are test pieces, 2 is ABS resin with a thickness of 1 mm, and 3 is the above A
It is a holding plate for BS resin 2. Reference numeral 4 is a clip whose surface is coated with an insulating paint for pressing and fixing the pressing plate 3, 5 is a battery, and 6 is an electric wire. The ends of the test pieces 1a and 1b are connected to the electric wire 6.

A DC voltage of 14 V was applied from the battery 5 to the two test pieces 1a and 1b shown in FIG. 1 and FIG. 2, soaked in tap water for 5 minutes, and then a dry-wet test of drying for 10 minutes was performed 50 times, The maximum leakage current during that time was measured with a high-sensitivity recorder (not shown).

The test results described above are shown in Tables 2 and 3.
As is clear from the results of Table 3, Example No. 1 of the present invention
In Nos. 18 to 18, cracking does not occur at all even when held for 1 hour at 600 ° C., which is the most brittle temperature during heating during heating, with a stress of 10 Kgf / mm ² applied.

Also, in the medium-high temperature tensile test in Tables 2 and 3, and the hot rolling test from 950 ° C. in Table 3, no abnormal breakage or cracking occurred.

Further, as shown in Table 2, in terms of migration resistance, Examples Nos. 1 to 18 of the present invention have a maximum leakage current of 0.48 to
It is as small as 0.56A and has excellent migration resistance.

That is, in the embodiment of the present invention, Mg 0.001 ~ 0.0
By containing 1% (not including 0.01%) and further containing 0.001 to 0.01% (not including 0.01%) of any one of Cr, Ti and Zr, the hot workability is improved. In addition, in the examples of the present invention, by incorporating Zn in an amount of 1.0 to 5.0%, migration resistance is also improved.

In contrast to the examples described above, in Comparative Examples Nos. 19 to 29 shown in Tables 2 and 3, penetration cracking occurred in the stress application test at 600 ° C. shown in Table 3.

In addition, in the medium and high temperature tensile tests in Tables 2 and 3, the elongation is low, and the cracking condition other than the cut portion in the high temperature tensile test at 950 ° C. causes severe intergranular cracking.

Furthermore, in Table 3, it was 1 in the hot rolling test at 950 ° C.
Ear cracks and surface cracks occurred on the pass, and it collapsed on the second pass.

Furthermore, in Comparative Examples Nos. 21, 22, 23, 26 and 29, as shown in Table 2, the maximum leakage current was 3.15 each.
It is as high as A ~ 4.35A. It has poor migration resistance.

That is, Comparative Examples No. 20 to No. 32 with respect to the examples of the present invention
In, Mg that satisfies the essential requirements of the present invention: 0.001 ~ 0.
01% (not including 0.01%) is not contained, and similarly, any one or more of Cr, Ti, and Zr is added to 0.001 to 0.01% (0.01
%) (Not included), so hot workability is poor.

Further, Comparative Examples Nos. 21, 22, 23 and 26 are inferior in migration resistance because they do not contain Zn: 1.0 to 5.0% which satisfies the essential requirements of the present invention.

In the examples of the present invention, the applied voltage at the time of the leakage current test was set to 14 V DC, but good migration resistance is exhibited even at 24 V DC applied voltage or 100 V AC applied voltage.

[Effects of the Invention] As described above, according to the present invention, brittleness at medium and high temperatures can be improved and hot working can be performed without homogenizing the ingot. By controlling the phenomenon, it is possible to provide a migration-resistant copper alloy for electric / electronic parts which is free from short circuit between electrodes and has excellent hot workability.

[Brief description of drawings]

1 and 2 are a plan view and a sectional view of an experimental apparatus for measuring the maximum leakage current. 1a, 1b …… Test piece, 2 …… ABS resin, 4 …… Clip, 5
...... Battery, 6 ...... Wire, 3 ...... Presser plate, 2a ...... Discharge hole

Claims (1)

[Claims] 1. Fe: 1.5 to 3.0% (same as below by weight%) P: 0.0
Contains 01 to 0.1%, Zn: 1.0 to 5.0%, Mg: 0.001 to 0.01% (not including 0.01%), and contains 0.001% of any one or more of Cr, Ti, and Zr.
1 to 0.01% (not including 0.01%), the balance consisting of Cu and unavoidable impurities, migration-resistant copper alloy for electric and electronic parts with excellent hot workability.