JPH06184676A - High strength and high electric conductivity copper alloy - Google Patents

Abstract

PURPOSE:To provide a copper alloy having electric conductivity, strength, spring characteristics, suitability to blanking and bendability required by the lead material of a semiconductor device and an electric conductive spring material. CONSTITUTION:A compsn. consisting of 25% to <43% Zn, 0.0005% to <0.05%, in total, of one or more among Ti, Zr, Hf and Th and the balance Cu with inevitable impurities or further contg. 0.01% to <1%, in total, of one or more among P, Sn, Si, Fe, Cr, B, Co, Mg, Ni, Al and Mn is imparted to a copper alloy and the average grain diameter of the copper alloy is optionally 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 (trade name) 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]

Then, the inventors of the present invention conducted extensive studies to achieve the above-mentioned object, and found that "the components of a Cu-Zn alloy having excellent strength and spring characteristics were adjusted. In the above, when an appropriate amount of Ti, Zr, Hf, or Th was added to this, punching which was not sufficient without adversely affecting the required properties as a lead material or conductive spring material for semiconductor equipment was not possible. The new fact that "workability and bending workability are remarkably improved" has been clarified. Furthermore, if the grain size of a copper alloy having such a composition is adjusted to a specific fine region, the punching workability and bending workability are improved. It has also been obtained.

The present invention has been completed on the basis of the above-mentioned findings and the like. "Copper alloy contains Zn: 25% or more and less than 43% (hereinafter,% representing a component ratio shall be% by weight), Ti, Zr, Hf
Or one or more of Th: 0.0005% or more and less than 0.05% in total, and if necessary P, Sn, Si, Fe, Cr, B, Co,
One or more of Mg, Ni, Al or Mn: The total amount is 0.01% or more and less than 1% and the balance is Cu and inevitable impurities, or in addition to this, the average crystal grain By adjusting the diameter to less than 25 μm, it has excellent electrical and thermal conductivity, workability, plating adhesion, solderability and heat resistance that can be sufficiently satisfied as a lead material for semiconductor equipment, and as a conductive spring material. It also has sufficient strength, spring characteristics, 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. The Zn content Zn has the function of ensuring the strength of the alloy, but if the content is less than 25%, the desired strength cannot be obtained even with the combined addition of other components, while at least 43% When Zn is contained in the ratio of, the conductivity decreases, and β peculiar to Cu-Zn system
The Zn content is defined as "25% or more and less than 43%" because phases are likely to occur and workability deteriorates due to this.

Ti, Zr, Hf or Th amount Ti, Zr, Hf, Th group IVa elements have the same action of improving punching workability and bending workability by adding a trace amount thereof, 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%".

[0012] P, Sn, Si, Fe, Cr, B, Co, Mg, Ni, Al or Mn amount P, Sn, Si, Fe, Cr, B, Co, Mg, Ni, Al and Mn are
Since they have the same effect of further improving the strength and heat resistance of the above-mentioned copper alloy, one or more of them are added if necessary. However, if the total content is less than 0.01%, the desired effect due to the above action cannot be obtained, while if the total content is 1% or more, the conductivity remarkably decreases.
The total content of these elements was defined as "0.01% or more and less than 1%".

[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 to obtain a thickness of 2
It was cast into a 0 mm ingot. The melting / casting was performed in the atmosphere.

[0016]

[Table 1]

[0017]

[Table 2]

Next, the ingot was heated and held at 800 ° C. for 1 hour and then hot-rolled to 8 mm, and then the thickness was increased.
Cold rolling was performed to 1.5 mm. Then 400
After annealing at 0 ° C for 1 hour, cold rolling to a thickness of 0.6 mm, annealing at 350-500 ° C for 1 hour to adjust the crystal grain size, and further cold rolling to 0.4 mm It was a plate material. Finally, strain relief annealing was carried out at 300 ° C. for 1 hour, and the average crystal grain size of each plate material thus obtained was examined and various properties were evaluated.

The "strength" and "elongation" are evaluated by a tensile test, the "heat resistance" is evaluated by measuring the softening temperature at a heating time of 5 minutes, and "electrical conductivity (heat dissipation)". Was evaluated by measuring the conductivity (% IACS).

Regarding the "bending workability", as shown in FIG. 1, a test piece having a width of 10 mm is bent at right angles to the rolling direction, and an inner bending radius of 0.4 mm (= plate thickness) is 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 "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”.

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. 18 of the present invention all have excellent strength, elongation, conductivity, heat resistance and good punching. It can be seen that the material exhibits bendability and bendability.

On the other hand, the comparative alloys Nos. 19 to 22 are Ti,
Since it does not contain Zr, Hf or Th, it is inferior in punching workability and bendability to the alloy of the present invention. Comparative alloy No.23
Has a low conductivity because the Co content as a subcomponent is 1% or more.

Further, the comparative alloy No. 24 has a low strength due to the low Zn content, while the comparative alloy No. 26 has a low electrical conductivity due to the excessive Zn content. Comparative alloy No.2
In No. 5, since the total content of Ti and Zr is 0.05% or more, the punching workability and bending workability are rather poor and the conductivity is low.

Alloy No. 22 is an example in which the crystal grains are coarse, and it can be confirmed that the punching workability and bending workability deteriorate when the crystal grain size is such large.

[0026]

[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. A weight ratio of Zn: 25% or more and less than 43%, T
One or more of i, 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. Zn by weight: 25% or more and less than 43%, T
One or more of i, Zr, Hf and Th: 0.0005% or more and less than 0.05% in total, P, Sn, Si, Fe, Cr, B, Co, Mg, Ni,
One or more of Al or Mn: 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 inevitable impurities. 3. By weight ratio, Zn: 25% or more and less than 43%, T
One or more of i, Zr, Hf, or Th: The total amount is 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. Zn by weight: 25% or more and less than 43%, T
One or more of i, Zr, Hf and Th: 0.0005% or more and less than 0.05% in total, P, Sn, Si, Fe, Cr, B, Co, Mg, Ni,
One or more of Al or Mn: 0.01% or more and less than 1% in total, with the balance being Cu and inevitable impurities,
A high-strength and high-conductivity copper alloy having an average crystal grain size of less than 25 μm.