JPH06235035A - High tensile strength and high conductivity copper alloy - Google Patents

Abstract

PURPOSE:To provide a copper alloy combining electrical conductivity, strength, spring properties, punching properties, bendability or the like required for the lead material of a semiconductor device and a conductive spring material. CONSTITUTION:The componental compsn. of a copper alloy is formed of a one contg. 0.05 to <3% Fe and total 0.0005 to 0.05% of one or more kinds among Ti, Zr, Hf and Th and contg., at need, total 0.01 to <1% of one or more kinds among Mn, Sn, P, Si, Ni, Zn, Cr, B, Be, Co, Mg and Al, and the balance Cu with inevitable impurities, or in addition to this, the average grain size is regulated to <25mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is suitable as a lead material for semiconductor devices such as transistors and integrated circuits (ICs) and as a conductive spring material for connectors, terminals, relays and switches. The present invention relates to a copper alloy having excellent punching workability and bending workability in addition to strength and conductivity.

[0002]

2. Description of the Related Art Conventionally, as a lead material for semiconductor devices, "COVAL (trade name: Fe-29wt), which has a low coefficient of thermal expansion and good adhesiveness and sealing property with elements and ceramics. % Ni-1
High-nickel alloys such as “6 wt% Co alloy)” or “42 alloy” have been used favorably.In recent years, however, ICs with high power consumption have been widely used as the integration degree of semiconductor circuits has improved. As a result of the fact that resin has been widely used as a sealing material and that the adhesion between the element and the lead frame has also been improved, the lead material for semiconductor equipment has been improved. The tendency to use a copper-based alloy with good heat dissipation has become prominent.

Regardless of the type of material, lead materials for such semiconductor devices are generally required to have the following characteristics. a) The lead is the electrical signal transmission part and at the same time the package.
Since it needs a function to release heat generated during the aging process and during circuit use to the outside, it has excellent heat and electrical conductivity. B) From the viewpoint of semiconductor device protection, "lead and mold "Adhesion" is important, so the coefficient of thermal expansion is close to that of the mold material. C) Various heating steps are added during packaging,
Good heat resistance, d) Most of the leads are made by punching and bending the lead material, so they have good workability, e ) Since the surface of the lead is plated with precious metal,
Good plating adhesion with these noble metals, f) Good because it is often soldered to the so-called "outer lead" that is exposed outside the encapsulant even after packaging. Good solderability, g) good corrosion resistance from the viewpoint of equipment reliability and life, and h) low price.

However, with respect to these various required characteristics, oxygen-free copper, tin-containing copper, phosphor bronze, Kovar (trademark) and 42 alloy, which have been conventionally used, have advantages and disadvantages. Was not always satisfactory. In particular, considering that the shape is becoming more complicated and the pins are becoming narrower with the increase in the number of leads and the miniaturization of the leads, considering that the material is required to have better punchability and bendability. However, it was difficult to say that the above-mentioned conventional materials have sufficient performance in these points.

On the other hand, as a spring material used for electrical equipment, measuring equipment, switches, connectors, etc., which are required to have excellent conductivity, corrosion resistance, strength, punching property, bending workability, etc. Therefore, copper alloys such as "brass" which is relatively cheap, "phosphor bronze" which has excellent spring characteristics, and "white silver" which has excellent corrosion resistance in addition to spring characteristics have been used.

However, when the above-mentioned copper alloy is examined as a spring material for the above-mentioned devices which are further improved in performance, brass is not sufficiently satisfactory in terms of strength and spring characteristics, and it is excellent in strength and spring characteristics. Even with white and phosphor bronze, as the lightness, thinness and shortness of parts have progressed, more severe punching and bending processes have come to be performed, so it is pointed out that these conventional materials are dissatisfied in terms of workability. It's coming.
Therefore, the emergence of an alloy exhibiting improved punching workability and bending workability and having excellent spring properties has been awaited.

From the above, the object of the present invention is to make use of the excellent electrical and thermal conductivity of the copper-based material, and at the same time, to sufficiently satisfy the strength as a lead material or a conductive spring material for semiconductor devices. , The spring characteristics, corrosion resistance, punching workability and bending workability were also combined to realize a copper alloy.

[0008]

Therefore, the inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and found that "the composition of a Cu-Fe alloy having excellent strength, spring characteristics and corrosion resistance is adjusted. After that, if an appropriate amount of Ti, Zr, Hf, or Th is added to this, it does not have a particular adverse effect on the required characteristics as a lead material or conductive spring material for semiconductor devices, but it is sufficient. The new fact that "punching workability and bending workability, which were not available, are significantly improved" has been clarified, and further "if the grain size of the copper alloy having such a composition is adjusted to a specific fine region, the punching workability and the workability are improved. The knowledge that the bending workability is further improved was also obtained.

The present invention has been completed on the basis of the above-mentioned findings and the like. "In a copper alloy, Fe: 0.05% or more and less than 3% (hereinafter,% representing a component ratio is% by weight), Ti, Zr,
One or more of Hf or Th: 0.0005% to 0.05% in total
Less than, if necessary, Mn, Sn, P, Si, Ni, Zn, C
One or more of r, B, Be, Co, Mg, Al: 0.01% in total
As a lead material for semiconductor devices, the composition should be such that the content is less than 1% and the balance is Cu and inevitable impurities, or in addition to this, the average crystal grain size is adjusted to less than 25 μm. It has excellent electrical and thermal conductivity that is fully satisfactory, and also has sufficient strength as an electrically conductive spring material, spring characteristics, electrical conductivity, and workability. "

Next, in the present invention, the component composition of the copper alloy,
The reason why the average grain size is limited as described above will be explained together with its action. Fe content Fe has the effect of ensuring the strength of the alloy, but if its content is less than 0.05%, the desired strength cannot be obtained even with the combined addition of other components, while at least 3% When Fe is contained in the proportion of, the workability is lowered and the conductivity is remarkably lowered. Therefore, the Fe content is "0.05% or more and less than 3%".
I decided.

Ti, Zr, Hf or Th amount Ti, Zr, Hf, and Th group IVa elements have the same action of improving punching workability and bending workability by adding a trace amount, and therefore, one or two of them is used. More than one seed is added. The mechanism by which the above-mentioned elements exert these actions is currently under study, but if the content of one or more of Ti, Zr, Hf or Th is less than 0.0005% in total, the above-mentioned action is obtained. The desired effect is not obtained, on the other hand, its content is 0.
If it exceeds 05%, the punching workability and bending workability are deteriorated, and the conductivity is also deteriorated. Therefore, the total content of these elements is defined as "0.0005% or more and less than 0.05%".

Mn, Sn, P, Si, Ni, Zn, Cr, B, Be, Co, Mg or Al amount Mn, Sn, P, Si, Ni, Zn, Cr, B, Be, Co, Mg and Al Has the same effect of further improving the strength and heat resistance of the above copper alloy, so one or more kinds of them are added if necessary. However, if the total content is less than 0.01%, the desired effect due to the above-mentioned action cannot be obtained, while if the total content is 1% or more, the conductivity is remarkably reduced, so the content of these elements is Is defined as "0.01% or more and less than 1%" in total.

[0013] In the crystal grain size of copper alloy according to the present invention, coarsening of the crystal grains exerts considerable adverse effect on punching processability and bending workability. In particular, when the average crystal grain size is 25 μm or more, the punching workability and bending workability are significantly deteriorated. Therefore, in order to secure good punching workability and bending workability, it is preferable to adjust so that the average crystal grain size does not exceed 25 μm.

As described above, the copper alloy according to the present invention has excellent strength, spring characteristics, electric conductivity, heat resistance, etc., and exhibits excellent punching workability and bending workability, and moreover, solderability. It also has excellent plating adhesion,
Hereinafter, the present invention will be described more specifically with reference to Examples.

[0015]

[Embodiment] Copper alloy having various component compositions shown in Tables 1 and 2 was melted in a high frequency melting furnace using electrolytic copper as a raw material, and thickness:
An ingot having a size of 30 mm, width: 60 mm, length: 120 mm was obtained. The melting / casting was performed in the atmosphere.

[0016]

[Table 1]

[0017]

[Table 2]

Next, 3 mm per side of this ingot
Surface removal is performed mechanically to remove surface defects, and 800 ~ 9
After heating and holding at a temperature of 50 ° C. for 2 hours, a plate material having a thickness of 6 mm was finished by hot rolling. Then, this is 1 at 500 ℃
After annealing for an hour and cold rolling to a plate with a thickness of 0.6 mm, and then adjusting the crystal grain size at a temperature of 350 to 600 ° C.,
By further cold rolling, a plate material having a thickness of 0.4 mm was obtained. Finally, strain relief annealing was performed at 300 ° C. for 1 hour.

The average crystal grain size of each plate material thus obtained was examined and various properties were evaluated. The "strength" and "elongation" were evaluated by a tensile test, and the "electrical conductivity (heat dissipation)" was evaluated by a conductivity (% IACS) measurement.

The "punching workability" is evaluated by observing the press fracture surface after punching, and when the fracture surface ratio {(fracture surface / plate thickness) × 100} is 20% or more.
“Good” and less than 20% were judged as “poor”.

Regarding the "bending workability", as shown in FIG. 1, a test piece having a width of 10 mm was bent at a right angle to the rolling direction, and an inner bending radius of 0.4 mm (= plate thickness) was repeatedly bent at 90 ° on one side. The measurement was performed and the number of times of bending until breakage (reciprocating once) was measured. The test was performed with n = 5, and the average value was used for evaluation.

The results of these evaluations are also shown in Tables 1 and 2 above. As is clear from the results shown in Tables 1 and 2, the alloys No. 1 to No. 23 of the present invention all have excellent strength, elongation and conductivity, and also have good punching workability and bending. It can be seen that it shows workability.

On the other hand, the comparative alloy No. 24 is compared with the alloy No. 1 of the present invention, and the comparative alloy No. 25 is the alloy No. 13 of the present invention.
Comparative alloy No. 26, compared with the present invention alloy No. 15, and comparative alloy No. 27, compared with the present invention alloy No. 11, both containing the same amount of Fe and other components Despite having the same grain size, it does not contain Ti, Zr, Hf, or Th, and therefore has poor punchability and bendability.

On the other hand, the comparative alloy No. 29 has a Ti content of 0.05.
%, The punching workability and bendability are rather poor, and the electrical conductivity is low, as compared with the alloy No. 1 of the present invention. In comparison alloy No. 30, 0.05% or more
Since Zr is contained, the punching workability and bendability are worse and the conductivity is lower than that of alloy No. 2 of the present invention.

The comparative alloy No. 31 has a low strength because the Fe content is small, and the comparative alloy No. 32 has a low strength.
Since the Fe content is too high, the strength is high, but the workability is poor, and the electrical conductivity is significantly reduced.

By the way, alloy No. 28 is an example in which the crystal grains are coarsened. As is clear from comparison with alloy No. 1, when the crystal grain size is such large, punching workability and bending work are possible. It can be confirmed that the sex becomes worse.

[0027]

[Summary of Effects] As described above, according to the present invention, the problems of punchability and bendability pointed out in the conventional alloys as the lead material and the conductive spring material of the semiconductor device are overcome, and It is possible to provide a high-strength and high-conductivity copper alloy that significantly improves the performance of the material, and an extremely useful effect in industry is brought about.

[Brief description of drawings]

FIG. 1 is an explanatory view of a 90 ° cyclic bending test method.

Claims (4)

[Claims] 1. Fe: 0.05% or more and less than 3% by weight,
One or more of Ti, Zr, Hf, and Th: A high-strength and high-conductivity copper alloy containing 0.0005% or more and less than 0.05% in total and the balance being Cu and inevitable impurities. 2. Fe: 0.05% or more and less than 3% by weight,
One or more of Ti, Zr, Hf or Th: Total amount of 0.0005% or more and less than 0.05% Mn, Sn, P, Si, Ni, Zn, Cr, B, Be, Co, Mg, Al One of Above: A high-strength and high-conductivity copper alloy containing 0.01% or more and less than 1% in total and the balance being Cu and unavoidable impurities. 3. Fe: 0.05% or more and less than 3% by weight,
One or more of Ti, Zr, Hf, or Th: The total amount contains 0.0005% or more and less than 0.05%, the balance is Cu and inevitable impurities, and the average crystal grain size is less than 25 μm. High strength and high conductivity copper alloy. 4. Fe: 0.05% or more and less than 3% by weight,
One or more of Ti, Zr, Hf or Th: Total amount of 0.0005% or more and less than 0.05% Mn, Sn, P, Si, Ni, Zn, Cr, B, Be, Co, Mg, Al One of Above: A high strength and high conductivity copper alloy containing a total amount of 0.01% or more and less than 1%, the balance being Cu and inevitable impurities, and having an average crystal grain size of less than 25 μm.