JPS63130739A - High strength and high conductivity copper alloy for semiconductor device lead material or conductive spring material - Google Patents

Abstract

PURPOSE:To improve bendability, solderability, plating suitability, and etching characteristic by limiting S content among the impurities of a Cu-Ni-Si alloy with a specific composition to a specific value or below. CONSTITUTION:This titled copper alloy has a composition which consists of, by weight, 0.4-4.0% Ni, 0.1-1.0% Si, and the balance Cu with inevitable impurities and in which S content among the above impurities is regulated to <=0.0015%. Further, as auxiliaries, 0.001-3.0% of one or more elements among Zn, P, Sn, As, Cr, Mg, Mn, Sb, Fe, Co, Al, Ti, Zr, Be, Ag, Pb, B, and lanthanide elements and/or <=0.0020% O may be incorporated in the above copper alloy. In this copper alloy, S is extremely easy to combine with Si and, when its content exceeds the upper limit, a large number of sulfides are formed and, moreover, O also combines with Si and, when its content exceeds the upper limit, a large number of inclusions are formed, so that bendability, solderability, plating suitability, and etching characteristic are remarkably deteriorated in both the above cases.

Description

[Detailed Description of the Invention] [Object] The present invention relates to a copper alloy suitable for lead materials for semiconductor devices such as transistors and integrated circuits (ICs), and conductive spring materials for connectors, terminals, relays, switches, etc. be.

[Prior art and problems]

Conventionally, lead materials for semiconductor devices have been Kovar (Fe-29Ni-16Co) and 42 alloy (F
High nickel alloys such as e-42Ni) have been preferred. However, in recent years, as the degree of integration of semiconductor circuits has improved, the number of ICs with high power consumption has increased, resins have been increasingly used as sealing materials, and improvements have been made to the bonding between elements and lead frames. As a result, copper-based alloys with good heat dissipation properties have come to be used as lead materials.

Generally, lead materials for semiconductor devices are required to have the following properties.

(1) Leads must exhibit excellent thermal and electrical conductivity, as they are required to act as an electrical signal transmission unit and also have the function of discharging heat generated during the packaging process and circuit use to the outside. .

(2) Since the adhesion between the lead and the mold is important from the viewpoint of protecting the semiconductor element, the thermal expansion coefficients of the lead material and the mold material should be similar.

(3) Since various heating processes are added during packaging,
Good heat resistance.

(4) Most leads are manufactured by punching or bending lead material, so the processability of these is good.

(5) Since the surface of the lead is plated with precious metals, the plating adhesion with these precious metals must be good.

(6) exposed outside the sealing material after packaging;
Many items are soldered to the so-called outer leads, so good soldering is a sign of good soldering.

(7) Good corrosion resistance from the standpoint of equipment reliability and lifespan.

(8) The price must be low.

Alloys conventionally used have advantages and disadvantages with respect to these various required characteristics, and no one has been found that satisfies these requirements.

In addition, conventional springs for electrical equipment, springs for measuring instruments, switches,
As materials for springs used in connectors and the like, inexpensive brass, nickel silver, which has excellent spring properties and corrosion resistance, or phosphor bronze, which has excellent spring properties, have been used.

However, brass has inferior strength and spring characteristics;
Nickel silver and phosphor bronze, both of which have excellent spring properties, contain 18% by weight of Ni and 8% by weight of Sn, so they have processing limitations such as poor hot workability in terms of raw materials and manufacturing. It was also an expensive alloy. Furthermore, when used for electrical equipment, etc., it has a drawback of low electrical conductivity. Therefore, the emergence of an inexpensive alloy with good electrical conductivity and excellent spring properties has been awaited.

[Structure of the invention]

The present invention has been made in view of the above, and aims to improve the drawbacks of conventional copper-based alloys and provide a copper alloy that has various properties suitable for use as lead materials and conductive spring materials for semiconductor devices. be.

In particular, the aim is to improve the Cu-Ni-8i alloy and provide a copper alloy that meets the requirements.

In other words, the Cu-Ni-8i alloy exhibits excellent conductivity and strength, and can be said to be an excellent copper alloy for both semiconductor device lead materials and conductive spring materials.
It did not show satisfactory properties in terms of etching and bending properties, and there was a need for improvement.

The present inventors investigated various causes of deterioration of these properties and found that Si oxides and sulfides were the cause, and by reducing the content of o and sulfur in the alloy to below a certain value, these factors could be suppressed. It was discovered that the characteristics could be improved.

The present invention includes: (1) Ni0.4-4.0wt%, Si0.1-1.0
wt%, the balance consists of Cu and unavoidable impurities,
A high-strength, high-conductivity copper alloy for semiconductor device lead material or conductive spring material, characterized in that the content of S among the impurities is 0°0015 wt% or less.

(2) Ni0.4-4.0wt%, Si0.1-1.0
wt%, and further contains Z0. P, S0.
As, Cr, Mg, M0. Sb, Fe.

Co, Al, Ti, Zr, Be, Ag, Pb, B.

The total amount of one or more lanthanide elements is O
,OO1 to 3.0wt%, and the balance consists of Cu and unavoidable impurities, and among the impurities, the content of S is O,00
A high-strength, high-conductivity steel alloy for use in semiconductor device lead materials or conductive springs, characterized in that the content is 15 wt% or less.

(3) Ni 0.4-4.0wt%, 5iO01-1.
0 wt%, the balance consists of Cu and unavoidable impurities, and among the impurities, the content of S is 0°0015 w t
% or less, and the content of O is 0.0020 wt% or less.

(4) Ni0.4-4.0wt%, Si0.1-1.0
wt%, and further contains Z0. P%Sn%
As, Cr, Mg%M0. Sb%Fe.

One or more of Co, Al, Ti, Zr, Be, Ag, Pb, B, and lanthanoid elements in a total amount of 0.0
01 to 3.0 wt%, with the balance consisting of Cu and unavoidable impurities, of which the content of S is O.0015
A high-strength, high-conductivity steel alloy for use in semiconductor device lead materials or conductive springs, characterized in that the content of zero is 0.0020 wt% or less.

It not only has excellent electrical and thermal conductivity, heat resistance, and spring properties as a semiconductor device lead material or conductive spring material, but also has significantly improved soldering properties, plating properties, etching properties, and bending properties. It is characterized by this.

[Detailed description of the invention]

Next, the reason for limiting the alloy components constituting the alloy of the present invention will be explained.

This is because Ni is co-added with Si in Cu and is precipitated as an intermetallic compound such as Ni2Si by performing aging treatment after solution treatment to improve strength without reducing conductivity. The reason for adding 4 to 4.0 wt% is 0.4
No improvement in strength was observed at less than 4.0 wt%.
This is because conductivity and workability will deteriorate if it exceeds this range.

Similarly, Si is an element that improves strength without reducing conductivity by co-adding with Ni and precipitating as an intermetallic compound, but the reason for adding 0.1 to 1.0 wt% is as follows.
If it is less than 0.1 wt%, no improvement in strength is observed, and 1. ．．
This is because if it exceeds 0 wt%, the electrical conductivity decreases, and the soldering properties and workability deteriorate. Desirably, the addition amount ratio of Ni and Si is close to the composition of the intermetallic compound (Ni2Si) (
Ni/5i)=(4/1) is good. Furthermore, Z0. P, S0. As%Cr%Mg, M0. Sb,F
e, Go%A1, Ti, Zr, Be, Ag%Pb%B,
0.00 of one or more lanthanide elements
The reason for adding 1 to 3.0 wt% is to improve the strength, but if it is less than 0.001 wt%, there is no effect.
This is because if it exceeds 3.0 wt%, the conductivity and workability will deteriorate.

The reason why the O content is set to be 0.0020% or less is that when O exists, it combines with Si to form oxides and becomes so-called inclusions that exist in steel.
This is because if the amount exceeds 0.20% by weight, a large number of inclusions will be formed, and the bending properties, soldering properties, plating properties, and etching properties will be significantly reduced.

The reason why the S content is set to 0.0015% by weight or less is that when S exists, Si is very easy to combine with S, easily becoming a sulfide and existing in steel. 0
．． This is because if the amount exceeds 0.015% by weight, a large amount of sulfides will be produced, and the bending properties, soldering properties, plating properties, and etching properties will be significantly reduced.

〔effect〕

In this way, by limiting O and S as impurities in the Cu-Ni-5i alloy, the alloy of the present invention improves bendability, soldering properties, plating properties, and etching properties, which have been the drawbacks of this alloy. can be significantly improved. In addition, its coefficient of thermal expansion is close to that of plastic, making it suitable for plastic packages as a lead material for semiconductor devices. Therefore, the alloy of the present invention is suitable as a lead material and a conductive spring material for semiconductor devices, and no prior art alloy has such comprehensive properties.

The material of the present invention will be explained below with reference to Examples.

〔Example〕

Ingots having various compositions of the alloys of the present invention shown in Table 1 were melted and cast using electrolytic copper or oxygen-free steel as raw materials in a high-frequency melting furnace in air, an inert atmosphere, or a reducing atmosphere. If electrolytic copper is used, it is recommended to dissolve it in a reducing atmosphere to reduce the oxygen content. Regarding S, a copper raw material having an S content of 0.0015% by weight or less was used for the alloy of the present invention.

Next, this was hot rolled at 900°C to form a 4m thick plate, then solution treated at 900°C for 5 minutes to give 1 solid and cold rolled to a thickness of 0.3mm. .

This was subjected to aging heat treatment at 400° C. for 2 hours to obtain a test material. Strength,
Elongation was evaluated by a tensile test, and springiness was evaluated by Kb value. Electrical conductivity (heat dissipation) is electrical conductivity (%IAC8)
It was shown by The bendability was determined by bending Ro and using a 3 mm bending jig, performing 90° reciprocating bending, and measuring the number of times until breakage.

Soldering is done using the vertical immersion method in a solder bath at 230±5℃ (
The solder was immersed in a solution (60% tin, 40% lead) for 5 seconds, and the wetting state of the solder was visually observed. The plating adhesion was measured by applying Ag plating to a thickness of 3 μm to the sample and testing it at 450°C for 5
The sample was heated for a minute and evaluated by visually observing the presence or absence of blisters on the surface. These results are shown in Table 1 along with comparative alloys.

From this table, it is clear that the alloy of the present invention has significantly improved bending properties, soldering properties, and plating properties, and has excellent properties as a high-strength, high-conductivity copper alloy.

Margin below

Claims (4)

[Claims] (1) Ni0.4-4.0wt%, Si0.1-1.0
wt%, the balance consists of Cu and unavoidable impurities,
A high-strength, highly conductive copper alloy for semiconductor device lead material or conductive spring material, characterized in that the content of S among the impurities is 0.0015 wt% or less. (2) Ni0.4-4.0wt%, Si0.1-1.0
wt%, and further contains Zn, P, Sn, as subcomponents.
As, Cr, Mg, Mn, Sb, Fe, Co, Al, T
i, Zr, Be, Ag, Pb, B, and one or more lanthanoid elements in a total amount of 0.001 to 3.0w
A high-strength, high-conductivity copper alloy for use in semiconductor device lead materials or conductive springs, characterized in that the balance is Cu and unavoidable impurities, and the content of S is 0.0015wt% or less among the impurities. . (3) Ni0.4-4.0wt%, Si0.1-1.0
wt%, the balance consists of Cu and unavoidable impurities,
A high-strength, highly conductive copper alloy for semiconductor device lead material or conductive spring material, characterized in that, among the impurities, the content of S is 0.0015 wt% or less and the content of O is 0.0020 wt% or less. . (4) Ni0.4-4.0wt%, Si0.1-1.0
wt%, and further contains Zn, P, Sn, as subcomponents.
As, Cr, Mg, Mn, Sb, Fe, Co, Al, T
i, Zr, Be, Ag, Pb, B, and one or more lanthanoid elements in a total amount of 0.001 to 3.0w
t%, the balance consists of Cu and unavoidable impurities, of which the content of S is 0.0015wt% or less, O
A high-strength, highly conductive copper alloy for use in semiconductor device lead materials or conductive springs, characterized in that the content thereof is 0.0020 wt% or less.