JPH04276037A - Copper alloy for lead frame - Google Patents

Abstract

PURPOSE:To offer a copper alloy for a lead frame having high thermal conductivity and electric conductivity, furthermore improved in strength and suitable as a lead frame material for a multipin. CONSTITUTION:This copper alloy contains 0.2 to 0.7% Be and furthermore contains 1.0 to 5.% Ni or one or >= two kinds of elements selected from 0.01 to 3.0% Co, 0.01 to 1.0% Zr, 0.01 to 1.0% Fe and 1.0 to 5.0% Ni.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is used as a material for manufacturing multi-pin IC lead frames which are required to have high electrical conductivity and excellent smoothness, etching properties, plating properties, and brazing properties. The present invention relates to a suitable copper alloy for lead frames.

0002

[Background Art] Recently, with the demand for downsizing of electronic devices,
There has been a demand for higher density, smaller size, and thinner ICs (semiconductor integrated circuits). For this reason, IC lead frames are also required to have an increased number of pins, narrow pin widths, and thin pin walls. For example, the number of pins is from 80 pins to 1
It has increased to 60 pins and then to 300 pins. The pin width has been narrowed from 0.65mm to 0.5mm to 0.3mm. As the number of these pins increases and the width of the pins becomes narrower, pins are being made thinner for convenience in etching and press processing.

As described above, due to the increase in the number of pins, narrower widths, and thinner walls, lead frames are required to have higher thermal conductivity in order to improve heat dissipation characteristics, and to increase the electrical conductivity in order to increase speed. In order to prevent deformation of the pin, there is a need to improve the strength of the pin.

[0004] Conventionally, materials for lead frames include 42 alloy containing 42% Ni (% indicates wt%; the same applies hereinafter) and the balance being Fe, or C7 alloy.
0250 (CDA standard; Copper Developo
pment Association) is used. This C70250 contains 2.2 to 4.2% Ni,
0.25-1.2% Si, 0.05-0.3% Mg
It is a copper alloy containing Cu, with the remainder being Cu.

[0005]

However, these conventional materials for lead frames have the disadvantage that alloy 42 has a low electrical conductivity, while C70250 has a disadvantage of low strength. For this reason, conventional materials for lead frames do not have characteristics that can respond to an increase in the number of pins, narrower widths, and thinner walls. Therefore, there is a need for the development of lead frame materials with improved thermal conductivity, electrical conductivity, and strength.

The present invention has been made in view of these problems, and provides a lead frame which has excellent thermal conductivity and electrical conductivity, and which has significantly improved strength compared to conventional lead frame materials. The purpose is to provide copper alloys for use in copper alloys.

[0007]

[Means for Solving the Problems] A copper alloy for lead frames according to the first invention of the present application contains Be: 0.2 to 0.7 wt% and Ni: 1.0 to 5.0 wt%, the balance being Cu. and unavoidable impurities, characterized in that (number of Be atoms)/(number of Ni atoms) is 0.9 to 1.2.

[0008] Furthermore, the copper alloy for lead frames according to the second invention of the present application contains Co: 0.01 to 3.0 wt%, Zr: 0
．． 01-1.0wt%, Fe: 0.01-1.0wt%
and Ni: 1.0 to 5.0 wt%, and Be: 0.2 to 0.7 wt%, with the balance consisting of Cu and inevitable impurities. , (number of atoms of Be)/(Ni, Co, Zr, F
The number of atoms of e) is 0.9 to 1.2.

Furthermore, one or both of Zn and Sn are added to the copper alloys of the first and second inventions in a total amount of 0.01.
It may contain ~0.05 wt%, or 1 of Si and Al
The total amount of one or two species may be 0.01 to 0.05 wt%.

0010

[Function] As a result of repeated various experimental studies in order to develop a copper alloy for lead frames having the above-mentioned characteristics, the inventors of the present invention have developed a copper alloy containing Be as the main additive component. , Ni or Co, Zr, Fe
It has been found that the objects of the present invention can be achieved by adding one or more of Ni and Ni. The present invention has been made based on such experimental facts.

Next, the reason for adding each component and the reason for limiting the composition will be explained.

Be: Be is added to improve the strength of the copper alloy. If the Be content is less than 0.2%, the strength cannot be sufficiently improved and the intended purpose will not be achieved. On the other hand, if the Be content exceeds 0.7%, even if more Be is added, a commensurate strength improvement effect cannot be obtained. Therefore, the Be content is 0.2 to 0.
Make it 7%.

Ni: Ni is an element effective in age hardening copper alloys. However, in the case of the first invention containing only Ni in addition to Be, if the Ni content is less than 1.0%, the copper alloy cannot be sufficiently age hardened. Moreover, when the Ni content exceeds 5.0%, the electrical conductivity of the copper alloy decreases. Therefore, in the first invention of the present application, the Ni content is set to 1.0 to 5.0%.

(Number of Be atoms)/(Number of Ni atoms)Be
This (
If the atomic ratio given by (number of Be atoms)/(number of Ni atoms) is less than 0.9, segregation of Ni occurs. As a result, conductivity and cleanliness decrease, and etching performance deteriorates. Furthermore, if particles are present on the surface of the plate material, the smoothness deteriorates, making it impossible to obtain sufficient plating and brazing properties. On the other hand, when the ratio exceeds 1.2, the workability of the copper alloy deteriorates. Therefore, the ratio is 0.9 to 1.2
shall be.

Co, Zr, Fe: These elements have the effect of refining the crystal grains of the copper alloy. This refinement of crystal grains improves flatness and improves etching performance. If the content of each of these elements is less than 0.01%, sufficient crystal grain refinement cannot be obtained. Further, when the Co content exceeds 3.0%, the Zr content exceeds 1.0%, or the Fe content exceeds 1.0%, the electrical conductivity decreases. Therefore, in the second invention of the present application, when these Co, Zr, and Fe are added, their contents are set to 0.01 to 3.0%, 0.01 to 1.0%, and 0.0%, respectively.
01-1.0%.

[0016] Since all of these elements have similar effects, any one of these elements may be added,
Moreover, a plurality of elements may be added in combination.

[0017] Also, in the second invention of the present application, Ni is
．． It can be contained in an amount of 0 to 5.0%. This results in
The age hardening effect of Ni can be obtained. In this case, the Ni content is 1.0 to 5.0%. If the Ni content is less than 1.0%, the effect of its addition cannot be obtained. Moreover, when the Ni content exceeds 5.0%, the electrical conductivity decreases.

(Number of Be atoms)/(Ni, Co, Zr,
In the second invention of the present application, (total number of Be atoms)/(Ni,C
If the atomic ratio given by the total number of atoms of Zr, Zr, and Fe is less than 0.9, some of Ni, Co, Zr, and Fe will not combine with Be, resulting in segregation. Therefore, the cleanliness is lowered and the etching performance is deteriorated. Furthermore, if particles exist on the surface of the plate material, the smoothness deteriorates, making it impossible to obtain sufficient plating and brazing properties. On the other hand, when the ratio exceeds 1.2, the workability of the copper alloy deteriorates. Therefore, the ratio is set to 0.9 to 1.2.

Zn, Sn Since Zn and Sn improve the migration resistance of copper alloys, in the first and second inventions of the present application, these Zn and Sn are added singly or in combination as necessary. However, if the contents of Zn and Sn are each less than 0.01%, the effect of their addition cannot be obtained. On the other hand, Zn, Sn
When the content exceeds 0.05%, the electrical conductivity decreases. For this reason, when Zn and Sn are added, their contents should be 0.01 to 0.05%, respectively.

Si, Al Si and Al improve the adhesion between the copper alloy base material and the oxide layer, so in the first and second inventions of the present application, one of these Si and Al or Add two types. However, if the contents of Si and Al are each less than 0.01%, the effect of their addition cannot be obtained. On the other hand, when the Si and Al contents each exceed 0.05%, hardness and electrical conductivity decrease. For this reason, when Si and Al are added, their contents should be 0.01 to 0.05%, respectively.

Since the copper alloy of the first invention of the present application contains Be and Ni in the above-mentioned predetermined contents, it has sufficient strength as an alloy for multi-pin lead frames. Furthermore, since this lead frame material is an alloy mainly composed of Cu, it has high thermal conductivity and excellent dissipation of heat generated in the IC chip. Furthermore, since this lead frame material is a Cu alloy, it has high electrical conductivity and is effective in increasing the speed of IC. Furthermore, since the copper alloy of the first invention of the present application does not cause Ni segregation, it has good flatness and excellent etching properties.

[0022] Furthermore, the copper alloy of the second invention of the present application includes Be and
Since it contains one or two of Ni, Co, Zr, and Fe in the above-mentioned predetermined content, it not only has sufficient strength as an alloy for multi-pin lead frames, but also has smoothness due to the refinement of crystal grains. The etching properties and etching properties are improved. Further, like the first invention, since it is an alloy mainly composed of Cu, it has excellent thermal conductivity and electrical conductivity.

Furthermore, the copper alloy according to claim 3 has improved migration resistance, and the copper alloy according to claim 4 has improved adhesion between the base material and the oxide layer.

[0024]

[Example] Next, an example of the present invention will be described.

[0025] An alloy having the composition shown in Table 1 below was melted in a vacuum melting furnace, and the obtained ingot was held at 880°C for 4 hours and then forged. Next, this forged ingot was heated at 900° C. for 2 hours and then hot rolled. Thereafter, it was cold rolled at a reduction rate of 80%. Next, this cold-rolled plate was heated to 940° C. for compaction treatment, and then cooled at a cooling rate of 30° C./sec. The cold rolling and compacting treatments were repeated until the ingot reached a predetermined thickness. after that,
Cold working was performed at a rolling reduction rate of 30% to obtain a plate material with a thickness of 0.125 mm. Finally, for this plate material, 45
Age hardening treatment was performed by heating at 0° C. for 2 hours.

[0026]

[Table 1]

[0027] The tensile strength, electrical conductivity, and cleanliness properties of the obtained copper alloy thin plate were measured. The results are shown in Table 2 below. However, in the cleanliness column, ◯ indicates good cleanliness, and × indicates low cleanliness.

As is clear from Table 2, the copper alloys of the examples of the present invention have excellent tensile strength, electrical conductivity, and cleanliness, and have sufficient properties as lead frame alloys for multi-pin applications. are doing. However, in Comparative Example 1, Be
Since the content is as low as 0.1%, the strength is insufficient. Also,
In Comparative Example 2, the Be content is too high at 0.8%, so the conductivity is too low and the cleanliness is also low. Furthermore, since the Ni content in Comparative Example 3 is as low as 0.9%, the strength is insufficient.

[0029]

[Table 2]

[0030]

Effects of the Invention Since the copper alloy for lead frames according to the present invention is a copper alloy containing Be as a main component, it has high electrical conductivity and thermal conductivity, has sufficiently high strength, and can be made narrower and thinner. It is useful as a copper alloy for multi-pin lead frames.

Claims (4)

[Claims] [Claim 1] Be 0.2-0.7wt%Ni
A copper alloy containing 1.0 to 5.0 wt% and the remainder consisting of Cu and unavoidable impurities, where (number of Be atoms)/(number of Ni atoms) is 0.
．． 9 to 1.2. A copper alloy for lead frames. [Claim 2] Co 0.01-3.0wt% Zr
One or more elements selected from 0.01 to 1.0 wt%, Fe 0.01 to 1.0 wt%, Ni 1.0 to 5.0 wt%, and Be 0.01 to 1.0 wt%.
2 to 0.7 wt%, with the remainder consisting of Cu and unavoidable impurities, (number of Be atoms)/(Ni, Co, Zr,
A copper alloy for lead frames, characterized in that the number of Fe atoms is 0.9 to 1.2. 3. The copper alloy for lead frames according to claim 1, further comprising 0.01 to 0.05 wt% of one or both of Zn and Sn in total. 4. The copper alloy for lead frames according to claim 1, further comprising a total of 0.01 to 0.05 wt% of one or both of Si and Al.