JPS6283441A - High strength alloy copper having high electric conductivity and superior resistance to stripping of solder by heat - Google Patents

Abstract

PURPOSE:To obtain a high strength Cu alloy having high electric conductivity and superior resistance to the stripping of solder by heat by adding specified amounts of Sn, P and Mn to Cu. CONSTITUTION:The composition of a Cu alloy is composed of, by weight, 2-10% Sn, 0.005-0.08% P, 0.05-1% Mn and the balance Cu with inevitable impurities. The composition may further contain 0.05-1% Ni or 0.05-1% one or more among Al, Be, Co, Cr, Fe, Hf, In, Mo, Mg, Pb, Si, Te, Ti, Zn and Zr.

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. In particular, it relates to a copper alloy that has excellent solder heat peeling resistance (here, heat peeling resistance refers to the property of a soldered material having a peeling resistant effect against the effects of heat, etc.).

[Prior art and problems]

Conventionally, lead materials for semiconductor devices include Kovar (Fe-29Ni46Co) and 4.2 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.

Improved alloys containing phosphor bronze and some additional elements have been widely used to meet these various required properties. However, in recent years, reliability requirements for semiconductors have become more stringent, and surface mounting types that support miniaturization have become more common, so solder heat resistance and peelability, which had not been considered an issue in the past, has become an extremely important characteristic item. It has become.

That is, the lead frame and the printed circuit board are soldered together, but during use, the temperature of the lead frame and the soldering area rises up to about 120° C. due to external temperatures and heat generated by energization. If exposed to such temperatures for a long period of time, the solder and lead frame may peel off, which may cause the semiconductor to malfunction. Therefore, when high reliability is required from the perspective of longevity, this solder heat peeling resistance is the best. This is one of the important characteristics. In particular, PPP (FLA
T PLAST CPACKAGE) and PLAST
CC (PLAST CLEADED CHIP CA)
The surface mounting type represented by RRIER) is not inserted into the printed circuit board, but is surface-contacted, so solder heat resistance and peelability are even more important.

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 poor strength and spring characteristics, and nickel silver has poor conductivity, so phosphor bronze is the most widely used material with high reliability.

Even in the field of conductive spring materials, Sn or solder plating is applied for reasons such as reducing contact resistance and improving corrosion resistance, and since soldering is often performed, solder heat-resistant peeling as mentioned above is applied. In recent years, reliability has become extremely important due to the demand for improved reliability.

Current phosphor bronze alloys cannot meet these strict requirements for heat-soldering peeling resistance, and the emergence of a high-strength, high-conductivity copper alloy with improved heat-soldering peeling resistance 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.

The present invention provides: (1) Sn2. O >10.0% by weight, P0.005-
0.08% by weight, M n 0 , 05-1, 0% by weight
A high-strength, high-conductivity copper alloy with excellent solder heat resistance and peelability, characterized in that the remainder consists of Cu and unavoidable impurities.

(2) Sn over 2.0~10.0% by weight, P0.005~
0.08% by weight, Nj 0.05-1.0% by weight, Mn
0, 05-1. , Q% by weight, the balance being Cu
A high-strength, high-conductivity copper alloy with excellent solder heat resistance and peelability, which is characterized by comprising: and unavoidable impurities.

(3) Sn over 2.0 to 10.0% by weight, P0.005
-0.08% by weight, M n 0 , 05-1, 0% by weight, and Al, Be, C0. Cr, Fe, Hf, In,
M0. 1 of Mg, Pb, Si, Te, Ti, Zn, Zr
A high-strength, high-conductivity copper alloy with excellent solder heat resistance and peelability, characterized in that it contains 0.05-1.0% by weight of one or more species, and the remainder consists of Cu and unavoidable impurities.

(4) Sn over 2.0 to 10.0% by weight, P 0.005
~0.08% by weight, Ni0.05-1.0% by weight, M
n 0 , 05-1, 0% by weight, and Al, Be, C
0. Cr, Fe, Hf, In, M0. Mg, Pb, S
i, Te, Ti, Zn, and Zr.
1. A high-strength, high-conductivity copper alloy with excellent solder heat resistance and peelability, characterized by containing 0.05 to 1.0% by weight, and the remainder consisting of Cu and unavoidable impurities.

It has excellent electrical and thermal conductivity, heat resistance, and heat resistance as a copper alloy for semiconductor device lead materials and as a conductive spring material.
It is characterized by not only good plating adhesion, solderability, corrosion resistance, and spring characteristics, but also markedly improved solder heat resistance and peelability.

[Detailed description of the invention]

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

The reason why the Sn content is set to more than 2.0 to 10.0% by weight is that if the Sn content is less than 2.0% by weight, sufficient strength cannot be obtained even with the co-addition of P; This is because if the content exceeds 10.0% by weight, the processability will be significantly reduced and the price will also increase. P content 0.005-0.08% by weight
The reason for this is that when the P content is less than 0.0.05% by weight, the improvement in strength and heat resistance is not significant;
This is because if it exceeds 8% by weight, the solder heat resistance and peelability will deteriorate significantly. Conventional phosphor bronze usually has a content of 0°1 to 0.15% by weight.
However, after various studies on the effect on solder heat resistance and peelability, it was found that there was a sudden negative effect when the amount exceeded 0.08% by weight. be.

The reason why the Mn content is set to 0.05~]-00 is as follows.
It was found that the addition of Mn greatly improved the solder heat resistance and that it was possible to further improve the solder heat resistance that had been significantly improved by specifying the P content, but when the Mn content was less than 0.05% by weight, This effect is small, and conversely, if the Mn content exceeds 1.0% by weight, the conductivity decreases significantly. Note that when adding Mn to increase the strength, it is desirable to add it in an amount exceeding 0.2% by weight.

The reason for setting the Ni content to 0.05 to 1.0% by weight is that N
This is because if the i content is less than 0.05% by weight, the expected strength will not be obtained and the effect of improving solder heat peeling resistance will not be obtained, and if it exceeds 1.0% by weight, the electrical conductivity will decrease significantly. It's for a reason. Further, as subcomponents Al, Be, C0.
Cr, Fe, Hf, In, M0. Mg, Pb, Si,...
Containing one or more of Te, Ti, Zn, and Zr improves strength and spring characteristics, but when the content is 0.0
If it is less than 5% by weight, little effect can be expected;
If it exceeds 0% by weight, the conductivity will decrease significantly.
．． 05 to 1.0% by weight. When the subcomponent Zn is added in a predetermined amount, the solder heat resistance and peelability become good. In order to particularly improve this solder heat resistance and peelability, it is desirable that the Zn content be 0.1 to 0.6% by weight.

〔effect〕

In this way, the alloy of the present invention achieves a remarkable improvement in solder heat resistance and peelability, which was previously unimaginable, by limiting the phosphor bronze-based components and by adding a small amount of Mn.
In addition to meeting the demands for high reliability of electrical and electronic equipment parts, this copper alloy has the excellent strength, spring characteristics, heat resistance, and electrical conductivity of phosphor bronze, and also has good solderability and plating adhesion. be. Note that plating adhesion can be improved by lowering the oxygen content in impurities. In this alloy system, it is recommended that the content be preferably 20 ppm or less by weight. 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 alloy of the present invention shown in Table 1 were melted and cast using electrolytic copper or oxygen-free copper as a raw material in a high-frequency melting furnace in air, an inert atmosphere, or a reducing atmosphere. Next, this was hot rolled at 800° C. to form a 4 m thick plate, and then solidified and cold rolled to a thickness of 1.0 mm. After annealing this at 500° C. for 11 hours, it was cold rolled into a 0.8 mm plate and evaluated as a lead material. For evaluation, strength and elongation were shown by a tensile test, heat resistance was shown by softening temperature at a heating time of 5 minutes, and electrical conductivity (heat dissipation) was shown by electrical conductivity (%IAC8). Solderability was evaluated by immersing the sample in a solder bath (60% tin, 40% lead) at 230±5° C. for 5 seconds using a vertical dipping method, and visually observing the state of solder wetting. Plating adhesion was evaluated by applying Ag plating to a thickness of 3 μm to a sample, heating it at 450° C. for 5 minutes, and visually observing the presence or absence of blisters on the surface. These results are shown in Table 1 along with comparative alloys.

In addition, in order to evaluate the material as a spring material, 1.0
After annealing the mm material at 500°C for 1 hour, cold rolling it into a 0.5mm thick plate, annealing it at various temperatures from 150 to 500°C to remove strain, and evaluating the strength and elongation using a tensile test. The spring properties were evaluated using the Kb value. In addition to this, the results of electrical conductivity are shown in Table 2 along with comparative alloys.

11 Regarding heat-resistant solder peeling, which is a key point of this patent, the material was plated with 5μ solder (60% Sn, 40% PB), kept in a constant temperature bath at 150°C for up to 2000 hours, and
It was taken out every 0 hours and bent at 90° and reciprocated once to check for peeling of the solder. These results are shown in Tables 1 and 2.
Shown in the table.

From these Tables 1 and 2, it is clear that the alloy of the present invention has significantly improved solder heat peeling resistance, improved solder stability, and has excellent properties as a high-strength, high-conductivity copper alloy.

Margin below

Claims (4)

[Claims] (1) Sn over 2.0 ~ 10.0 wt%, P 0.005 ~
0.08% by weight, Mn 0.05-1.0% by weight,
A high-strength, high-conductivity copper alloy with excellent solder heat resistance and peelability, characterized in that the remainder consists of Cu and unavoidable impurities. (2) Sn over 2.0 ~ 10.0% by weight, P 0.005 ~
0.08% by weight, Ni0.05-1.0% by weight, Mn0
．． A high-strength, high-conductivity copper alloy having excellent solder heat resistance and peelability, characterized in that it contains 0.05 to 1.0% by weight, and the remainder consists of Cu and unavoidable impurities. (3) Sn over 2.0 ~ 10.0% by weight, P 0.005 ~
0.08% by weight, Mn 0.05-1.0% by weight, and A
l, Be, Co, Cr, Fe, Hf, In, Mo, Mg
, Pb, Si, Te, Ti, Zn, and Zr in an amount of 0.05 to 1.0% by weight, with the remainder consisting of Cu and unavoidable impurities. Excellent high strength and high conductivity copper alloy. (4) Sn over 2.0 ~ 10.0% by weight, P 0.005 ~
0.08% by weight, Ni0.05-1.0% by weight, Mn0
．． 05 to 1.0% by weight, and Al, Be, Co, Cr,
Fe, Hf, In, Mo, Mg, Pb, Si, Te, T
0.05 to 1.0 of one or more of i, Zn, and Zr
A high-strength, high-conductivity copper alloy with excellent solder heat resistance and peelability, characterized in that the balance consists of Cu and unavoidable impurities.