JPH06172896A - High-strength and high-conductivity copper alloy - Google Patents

Abstract

PURPOSE:To obtain a copper alloy combining electric conductivity, strength, spring characteristic, punchability, bendability, etc., required of a lead material for semiconductor device and a conductive spring material. CONSTITUTION:The copper alloy has a composition consisting of 0.8-10% Sn, 0.001-0.4% P, 0.0005-0.05%, in total, of one or more elements among Ti, Zr, Hf, and Th, and the balance Cu with inevitable impurities or further containing, if necessary, 0.01-1%, in total, of one or more elements among Si, Zn, Fe, Cr, B, Be, Co, Mg, Ni, Al, and Mn, or further, in addition to the above, the average crystalline 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 conducted extensive studies to achieve the above-mentioned object, and found that "the composition of a Cu-Sn-P-based alloy having excellent strength and spring characteristics is adjusted. After this, if an appropriate amount of Ti, Zr, Hf or Th is added to this, it will not be said to be sufficient without adversely affecting the required characteristics as a lead material or conductive spring material for semiconductor devices. The punching workability and bending workability are significantly improved. "
It is also possible to obtain the finding that "when the grain size of a copper alloy having such a composition is adjusted to a specific fine region, its punching workability and bending workability are further improved". did it.

The present invention has been completed on the basis of the above-mentioned findings and the like. "Copper alloy contains Sn: 0.8% or more and less than 10% (hereinafter,% representing a component ratio is represented by weight%), P: 0.001% to less than 0.4%, Ti, Zr, Hf
Or one or more of Th: 0.0005% or more and less than 0.05% in total, and if necessary Si, Zn, Fe, Cr, B, Be, Co,
One or more of Mg, Ni, Al or Mn: The total composition contains 0.01% or more and less than 1% and the balance is Cu and inevitable impurities, or the average crystal grain in addition to this By adjusting the diameter to less than 25 μm, excellent electrical and thermal conductivity, heat resistance, workability, plating adhesion, solderability, corrosion resistance, and even a conductive spring that can be sufficiently satisfied as a lead material for semiconductor devices. Sufficient strength as a material,
It has a great feature in that it has both 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. Sn content Sn has the effect of ensuring the strength of the alloy, but if the content is less than 0.8%, the desired strength cannot be obtained even with the combined addition of other components, while at least 10% Since the conductivity decreases when Sn is contained in the ratio of, the Sn content is defined as "0.8% or more and less than 10%".

The P content P has the function of ensuring the strength and heat resistance of the alloy. However, if the content of P is less than 0.001%, the desired strength and heat resistance improving effect of P content cannot be obtained, while the P content Quantity
When the content is 0.4% or more, the conductivity is remarkably lowered regardless of the Sn content, so the P content was defined as "0.001% or more and less than 0.4%".

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, 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%".

Si, Zn, Fe, Cr, B, Be, Co, Mg, Ni, Al
Or Mn amount Si, Zn, Fe, Cr, B, Be, Co, Mg, Ni, Al and Mn,
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%".

[0014] 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, electrical conductivity, heat resistance, etc., and exhibits good punching workability and bending workability, and also solderability. Although it is also excellent in plating adhesion and corrosion resistance, the present invention will be described in more detail below with reference to examples.

[0016]

[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.

[0017]

[Table 1]

[0018]

[Table 2]

Next, this ingot was homogenized and annealed at 700 ° C. for 4 hours, then face-cut, and cold-rolled to a thickness of 1.5 mm. Subsequently, after further annealing at 500 ° C. for 1 hour, cold rolling is performed to a thickness of 0.6 mm, and 350 to 600
After annealing at a temperature of ℃ for 1 hour to adjust the crystal grain size, further cold rolling was performed to obtain a plate having a thickness of 0.4 mm. And finally 3
Strain relief annealing was carried out at 00 ° 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 the "electrical conductivity (heat dissipation)" is evaluated. Was conducted by measuring conductivity (% IACS).

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 right angles to the rolling direction, and a bending of 90 ° was repeated on one side at an inner bending radius of 0.4 mm (= plate thickness). 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. 19 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, Comparative Alloy No. 20 is the alloy of the present invention.
Compared with No. 1, comparative alloy No. 21 is compared with the present invention alloy No. 13, comparative alloy No. 22 is compared with the present invention alloy No. 7, and comparative alloy No. 23 is the present invention alloy No. The same amount compared to .11
Despite containing Sn, P and other components and having the same crystal grain size, since they do not contain Ti, Zr, Hf or Th, they have poor punching workability and bendability.

Similarly, since the comparative alloy No. 26 contains Zr in an amount of 0.05% or more, the punching workability and bending workability are rather worse and the conductivity is lower than the invention alloy No. 1. In addition, Comparative Alloy No. 27 has a low Sn content and therefore low strength, while Comparative Alloy No. 28 has a too low Sn content and thus a low electrical conductivity. Furthermore, comparative alloy No. 30
Has a low conductivity because the P content is too high. The comparative alloy No. 25 has a low conductivity because the Ni content is as high as 1% or more.

By the way, alloy No. 24 is an example in which the crystal grains are coarsened. As is clear from comparison with alloy No. 1, if 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 bending workability, which have been pointed out in the conventional alloys for the lead material and conductive spring material of semiconductor devices, are overcome. 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 Sn: 0.8% or more and less than 10%, P: 0.001% or more and 0.4%
Less than, one or more of Ti, Zr, Hf or Th: 0.00 in total
A high-strength and high-conductivity copper alloy, characterized by containing at least 05% and less than 0.05%, and the balance being Cu and inevitable impurities. 2. By weight ratio, Sn: 0.8% or more and less than 10%, P: 0.001% or more and 0.4%
Less than, one or more of Ti, Zr, Hf and Th: 0.00 in total
05% or more and less than 0.05%, Si, Zn, Fe, Cr, B, Be, Co, M
One or more of g, Ni, Al or Mn: 0.01% or more in total 1
% And a balance of Cu and inevitable impurities, and a high strength and high conductivity copper alloy. 3. Sn: 0.8% or more and less than 10%, P: 0.001% or more and 0.4% by weight
Less than, one or more of Ti, Zr, Hf or Th: 0.00 in total
A high-strength and high-conductivity copper alloy, characterized by containing at least 05% and less than 0.05%, the balance being Cu and unavoidable impurities, and having an average crystal grain size of less than 25 μm. 4. By weight ratio, Sn: 0.8% or more and less than 10%, P: 0.001% or more and 0.4%
Less than, one or more of Ti, Zr, Hf and Th: 0.00 in total
05% or more and less than 0.05%, Si, Zn, Fe, Cr, B, Be, Co, M
One or more of g, Ni, Al or Mn: 0.01% or more in total 1
%, With the balance being Cu and unavoidable impurities, and having an average crystal grain size of less than 25 μm.