JPH06192769A - 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 0.05% to <1% Cr, 0.0005% to <0.05%, in total, of one or more among Ti, Hf and Th and the balance Cu with inevitable impurities or further contg. 0.01% to <1%, in total, of one or more among Si, Sn, P, Fe, Cr, B, Be, 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 1. Field of the Invention The present invention is suitable as a lead material for semiconductor devices such as transistors and integrated circuits (ICs), and a conductive spring material for connector terminals, relays, switches, etc., having high strength and conductivity. In addition to the above, the present invention relates to a copper alloy having excellent punching workability and bending workability.

[0002]

2. Description of the Related Art Conventionally, as a lead material for semiconductor devices, "Kovar (trade name: Fe-29 wt% Ni) having a low coefficient of thermal expansion and good adhesiveness and sealing property with elements and ceramics.
High nickel alloys such as "-16 wt% Co alloy)" or "42 alloy" have been used favorably.

However, in recent years, ICs with high power consumption have come to be used more and more as the degree of integration of semiconductor circuits has increased, and there have been circumstances such as that a large amount of resin has been used as a sealing material. As a result, the tendency to use a copper-based alloy with good heat dissipation as a lead material for semiconductor devices has become prominent.

Regardless of the type of material, the following characteristics are generally required for the lead material of such a semiconductor device.

(1) The lead is an electric signal transmitting part and at the same time needs to have a function of radiating heat generated during the packaging process and during use of the circuit to the outside, so that it has excellent heat and electric conductivity. . (2) Since the "adhesion between the lead and the mold" is important from the viewpoint of protecting the semiconductor element, the coefficient of thermal expansion is close to that of the molding material. (3) Heat resistance is good because various heating steps are added during packaging.

(4) For the lead, the lead material is punched out,
Also, since most of them are manufactured by bending, they must have good workability. (5) Since the surface of the lead is plated with a noble metal, the adhesion of the plating to these noble metals must be good.

(6) Since soldering is often performed on the so-called "outer lead portion" exposed to the outside of the encapsulant even after packaging, it should exhibit good solderability. (7) Good corrosion resistance from the viewpoint of equipment reliability and life. (8) The price is low.

[0008]

However, oxygen-free copper, tin-containing copper, phosphor bronze, Kovar (trade name) and 4 which have been used conventionally are used for these various required characteristics.
Each of the two alloys had merits and demerits, and it was not possible to satisfy all of the above characteristics.

In consideration of the fact that the shape is becoming more complicated and the pin is becoming narrower with the increase in the number of pins of the lead and the miniaturization of the lead, and that the material is required to have better punchability and bending workability. 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 also required to have excellent conductivity, corrosion resistance, strength, punchability, bending workability, etc., they have been comparatively used in the past. Copper alloys such as inexpensive “brass”, “phosphor bronze” with excellent spring characteristics, and “white silver” with 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 parts become lighter, thinner and smaller, more severe punching and bending processes have been applied, so it is pointed out that conventional materials are dissatisfied in terms of workability. It's coming. Therefore, the emergence of an alloy exhibiting further improved punching workability and bending workability and having excellent spring properties has been awaited.

Therefore, an object of the present invention is to make use of the excellent electric and thermal conductivity of copper-based materials, and at the same time, to obtain the strength and spring which are sufficiently satisfactory as a lead material or a conductive spring material for semiconductor devices. It was placed on realizing a copper alloy that also has properties, corrosion resistance, punching workability, and bending workability.

[0013]

Therefore, the inventors of the present invention have conducted extensive studies to achieve the above-mentioned object, and found that "the components of a Cu-Cr alloy having excellent strength and spring characteristics are adjusted. However, if an appropriate amount of Ti, Hf, or Th is added to this, punching workability and bending work that could not be said to be sufficient without adversely affecting the required characteristics as the lead material or conductive spring material of semiconductor devices Of the copper alloy having such a composition is further improved in punching workability and bending workability. I was able to obtain the knowledge.

The present invention has been completed on the basis of the above-mentioned findings and the like. "In a copper alloy, Cr: 0.05% or more and less than 1% (hereinafter,% representing a component ratio is defined as% by weight). ),
One or more of Ti, Hf or Th: 0.0 in total
Containing 005% or more and less than 0.05%, or further containing Si, Sn, P, Fe, B, Be, Co, Mg, Zn,
One or more of Al or Mn: a total composition of 0.01% or more and less than 1% and the balance being Cu and inevitable impurities, or an average crystal grain size of 25 μm By adjusting to less than, the strength, spring characteristics, conductivity, sufficient as an excellent electrical and thermal conductive spring material that can be sufficiently satisfied as the lead material of the semiconductor device,
It has a great feature in that it has both processability ".

Next, the reason why the component composition and average crystal grain size of the copper alloy are limited as described above in the present invention will be explained together with its action.

Cr content: Cr acts to secure the strength of the alloy, but if the content of Cr is less than 0.05%, the desired strength of 300 N / mm ² or more cannot be obtained, while 1
Since the elongation decreases to 4% when Cr is contained in a proportion of not less than%, the Cr content is defined as "0.05% or more and less than 1%".

Ti, Hf or Th amount: Ti, Hf, T
Since the addition of a small amount of h has the same effect of improving punching workability and bending workability, one or more additions are made. The mechanism by which the above elements exert these actions is currently under study, but the total content of one or more of Ti, Hf or Th is 0.0.
If it is less than 005%, the desired effect due to the above-mentioned action cannot be obtained. On the other hand, if the total content is 0.05% or more, punching workability and bending workability are deteriorated conversely, and conductivity is also increased. Therefore, the total content of these elements was determined to be “0.0005% or more and less than 0.05%”.

Si, Sn, P, Fe, B, Co, Mg,
Zn, Al or Mn amount; Si, Sn, P, Fe, B,
Co, Mg, Zn, Al or Mn have the same effect to further improve 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 the total content is 1%.
Since the electrical conductivity remarkably decreases when the content is higher than the above, the total content of these is defined as "0.01% or more and less than 1%".

Crystal grain size: In the copper alloy according to the present invention, coarsening of the crystal grains has a considerable adverse effect on punching workability and bending workability. Especially the average crystal grain size is 25 μm
If it becomes the above, punching workability and bending workability will become remarkable. Therefore, in order to secure good punching workability and bending workability, it is preferable to adjust so that the average crystal grain size is not 25 μm or more.

As mentioned above, the copper alloy according to the present invention is
It has excellent strength, spring characteristics, electrical conductivity, heat resistance, etc., and shows good punching and bending workability.
Moreover, although the solderability and the plating adhesion are excellent, the present invention will be described in more detail with reference to the following examples.

[0021]

[Examples] Electrolytic copper was used as a raw material to melt copper alloys having various component compositions shown in Tables 1 and 2 at 1200 ° C. in a high frequency melting furnace, and after skinning, hot rolling was performed to a thickness of 6 mm. After this material is skinned, quenching is performed from 100 ° C., cold rolling, aging treatment, rolling are performed, and finally strain relief annealing is performed,
The plate was 0.3 mm thick. The tensile strength, elongation and bendability of these materials were investigated.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

The tensile strength was measured by taking a JIS No. 5 tensile test piece in the direction parallel to the rolling direction and performing a tensile test. Electrical conductivity (heat dissipation) is evaluated by conductivity (% I
It was evaluated by measuring ACS). The "punching workability" is evaluated by observing the press fracture surface after punching, and the fracture surface ratio [(fracture surface) / (plate thickness) x 100]
When it was 20% or more, it was judged as "good", and when it was less than 20%, it was judged as "bad".

Regarding bending workability, as shown in FIG. 1, a test piece having a width of 10 mm was subjected to an inward bending radius of 0.3 mm.
(= Plate thickness), 90 degree bending is repeated on one side at right angles to the rolling direction, and the number of bendings until breakage (1 time for reciprocation)
Was measured. The test was conducted at n = 5, and the average value was evaluated. 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, electrical conductivity and heat resistance and are good. It can be seen that it exhibits excellent punching workability and bending workability.

On the other hand, the comparative alloy No. 20 is in comparison with the invented alloy No. 1, and the comparative alloy No. 21 is in the invented alloy No. 1.
Comparative alloy No. 22 compared to invention alloy No. 7 and comparative alloy No. 23 to invention alloy No. 11
Compared with Ti, Hf or Th, despite containing the same amount of Cr and other components and having the same crystal grain size.
Since it does not contain, it is inferior in punching workability and bendability. Further, the comparative alloy No. 26 has a low strength due to the low Cr content, while the comparative alloy No. 27 has a small elongation due to the excessive Cr content.

Further, the comparative alloy No. 25 has a Zn content of 1%.
Since it is higher than the above, the conductivity is low. by the way,
Alloy No. 24 is an example of a coarse crystal grain,
As is clear from the comparison with Alloy No. 1, it can be confirmed that the punching workability and bending workability are deteriorated when the crystal grain size is such large.

[0030]

As described above, according to the present invention,
Overcoming the problems of punchability and workability pointed out in conventional alloys as lead materials and conductive spring materials for semiconductor devices,
As it becomes possible to provide a high-strength and high-conductivity copper alloy that greatly improves the performance of the material, a very useful effect in industry is brought about.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a bending workability test.

Claims (4)

[Claims] 1. By weight ratio, Cr: 0.05% or more 1
%, One or more of Ti, Hf, or Th: High strength and high conductivity characterized by containing 0.0005% or more and less than 0.05% in total and the balance being Cu and unavoidable impurities. Copper alloy. 2. A weight ratio of Cr: 0.05% or more 1
%, One or more of Ti, Hf or Th: 0.0005% or more and less than 0.05% in total, Si, Sn,
P, Fe, B, Be, Co, Mg, Zn, Al or M
One or more of n: 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. In a weight ratio, Cr: 0.05% or more 1
%, One or more of Ti, Hf, or Th: 0.0005% or more and less than 0.05% in total, with the balance being Cu and inevitable impurities, and having an average crystal grain size of less than 25 μm. A high-strength and highly conductive copper alloy. 4. A weight ratio of Cr: 0.05% or more 1
%, One or more of Ti, Hf or Th: 0.0005% or more and less than 0.05% in total, Si, Sn,
P, Fe, B, Be, Co, Mg, Zn, Al or M
One or more of n: 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.