JPH0499139A - Copper-base alloy - Google Patents

Abstract

PURPOSE:To offer a copper-base allay for electronic equipment having high strength and high electrical conductivity, and provided with high temp.-long time reliability for soldering and plating by incorporating each specified amt. of Si, P, Ni and Zn into copper as essential components. CONSTITUTION:This copper-base alloy has a compsn. contg., by weight, total 1 to 4% of Si, P and Ni, in which the weight ratio of Ni/(Si+P) furthermore lies in the range of 4 to 6, moreover contg. 0.5 to 8% Zn and the balance copper with inevitable impurities. For manufacturing this copper-base alloy, at first, a raw material contg. copper, Si, P, Ni and Zn by the above weight ratio is melted by a high frequency electric furnace or the like and is thereafter cast into a mold to manufacture an ingot. Next, its surface is faced, is repeatedly subjected to cold rolling and heat treatment and is finished into a sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copper-based alloy used for lead frames, connectors, etc. of integrated circuits for electronic devices.

(Prior art) As a conventional copper alloy for electronic devices, CDA/C194
00 alloy or high conductivity type composed of around 0.1% Sn, Fe, etc. (tensile strength 50 kgf/s+*2
below, electrical conductivity of 60% 1^CS or higher) or high-strength type such as phosphor bronze (strength is at the same level as 42^11oy, electrical conductivity of 20% 1^CS or higher) or 1. ing. In addition, other high-strength types include 42^1
1oy (F e -42%Ni) is used, and monovalent beryllium copper alloy etc. are used as a high strength type.

However, all of these alloys have their own advantages and disadvantages in terms of electrical conductivity, strength level, price, etc. required in fields such as lead frames and connectors, and none of them could fully satisfy these requirements. .

For example, copper alloys with excellent conductivity are often used in lead frames for integrated circuits because they are suitable for dissipating heat generated by higher levels of integration, or materials are being used as parts become smaller. The demand for thinner products cannot be fully met because the strength level is insufficient. For this reason, especially in QFP (clad flat package) type IC packages that require high strength, 42^
110y is still widely used.

Due to these circumstances, we are currently developing alloys that are at a level that can meet a wide range of needs, that is, they have the same strength as 42AIIoy (tensile strength of about 70 kgf/am2) and 40% lA.
Si has an electrical conductivity higher than C3.

A high-strength, high-conductivity copper-based alloy containing P and Ni as constituent components has been developed and is already in practical use.

(Problems to be Solved by the Invention) However, although the above-mentioned copper base metal has properties at a practical level in terms of strength and conductivity, it does not provide high-temperature and long-term reliability in high-temperature environments during soldering or tin plating. In terms of properties (solder/plating heat resistance), it has not yet reached a sufficient level, and improvements in the negative layer are required.

This invention was made by focusing on these conventional problems, and provides a method for electronic devices that has high strength, high conductivity, and excellent high-temperature and long-term reliability of soldering and plating. The purpose is to provide copper-based alloys.

(1 [Means for Solving Problem]) The copper-based alloy provided by the present invention contains Si, P, and Ni in a total amount of 1 to 4 q% by weight, and the ratio of these elements/Ni
/(Si+P) is in the range of 4 to 6 in terms of weight ratio, and contains Zn in an amount of 0.5 to 8% by weight, with the remainder consisting of copper and unavoidable impurities.

The total amount of Si, P and Ni is 1 to 4% by weight, and the ratio of these elements Ni/(Si+P) is 4 to 6% by weight.
This is because we found that within this range, each element or intermetallic compound is generated at a high rate, which contributes to improving tensile strength and does not significantly reduce electrical conductivity. .

In other words, the ratio of each element Ni/(Si+P) is ITt
When the amount ratio is 4 to 6, intermetallic compounds are efficiently generated, and the generation efficiency increases when the total content of Si, P, and Ni is 1 to 4% by weight, and the tensile strength increases. This is because an improvement is observed, and within this range, no significant decrease in electrical conductivity is observed.

Zn is added for the purpose of improving the high-temperature and long-term reliability of solder and tin plating, and the F limit of addition is set at 0.5% by weight. This is because it is not possible to obtain much, and the upper limit was set at 8%.
This is because if it exceeds this, the stress corrosion susceptibility increases.

(Function) In this invention, since the content of Si, P, and Ni and the ratio of each element, Ni/(S i + P,), are limited to the above range, these elements or This gives it high tensile strength without compromising its high electrical conductivity. Further, Zn in the above range improves high-temperature and long-term reliability during soldering and tin plating without increasing stress corrosion susceptibility.

(Example) An embodiment of the present invention will be described below.

Samples of components in Table 1, 1 to 11 (No, 2.4°7
~10 are examples, No. 1.3, 5, 6.11 are comparative examples) were melted in a high frequency electric furnace, and then cast into a mold to a thickness of 20.
An ingot with a thickness of 1 mm was made, and after its surface was solidified, cold rolling and heat treatment were repeated, and a final cold working of 37% was performed, and the ingot was placed on a plate with a thickness of 0.25 sa+. Before the final rolling, it was heated at 800°C for 30 minutes, quenched in water, and then tempered at 450°C for 2 hours.

Table 1 shows various characteristics of Examples and Comparative Examples.

As is clear from Table 1, all of the samples in the examples were excellent in terms of tensile strength, electrical conductivity, and stress corrosion susceptibility, and were also significantly superior in terms of soldering heat resistance. I understand.

In contrast, Comparative Example Sample No. 1 has excellent solder heat resistance and electrical conductivity, but has low tensile strength, and Comparative Example No. 3. No. 6 had sufficient tensile strength and electrical conductivity, or had poor solder heat resistance. In addition, sample No. 5 of the comparative example. Samples No. 11 are both excellent in tensile strength and soldering heat resistance, but Sample No. 5 has low electrical conductivity, and Sample No. 11 can provide stress corrosion sensitive gold.

Claims (1)

[Claims] Contains 1 to 4% by weight of Si, P, and Ni in total, and the ratio of these elements Ni/(Si+P) is 4 to 6 by weight.
A copper-based alloy containing 0.5 to 8% by weight of Zn, with the remainder consisting of copper and unavoidable impurities.