JPS6338545A - High strength conductive copper alloy - Google Patents

Abstract

PURPOSE:To obtain a Cu alloy having superior solderability, adhesion to plating and resistance to stress corrosion cracking by reducing the O2 content in a phosphor bronze type Cu alloy and adding specified amounts of Cr, Fe or Co and one or more among Zn, B, Al, Mg, Si and Ti to the alloy. CONSTITUTION:A phosphor bronze type Cu alloy contg. 2-8wt% Sn and <0.2wt% P is deoxidized to <=0.0025wt% O2 content by adding Mn as a deoxidizing agent so that 0.01-0.5wt% Mn remains in the alloy and 0.05-0.5wt% Cr, 0.05-1.5wt% Fe or Co and 0.01-5wt% in total of one or more among 0.01-5% Zn, 0.01-0.1% B, 0.01-1% Al, 0.01-0.2% Mg, 0.01-0.5% Si and 0.01-0.2% Ti are added to the alloy. A high strength conductive Cu alloy having superior various characteristics and suitable for use as a lead member or a spring material for electronic and electrical apparatuses is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-strength conductive steel alloy suitable for lead members, spring members, etc. used in electronic and electrical equipment.

(Prior Art) Conventionally, phosphorus 2 has been mainly used in connectors, various switches, electromagnetic switches, various springs, etc. used in electronic and electrical equipment.

Phosphor bronze contains Sn3-9wt% (hereinafter abbreviated as "chi"), PO1
It is a copper alloy containing 0.05 to 0.55% Sn, and its characteristics are that the conductivity and tensile strength can be appropriately selected depending on the purpose depending on the Sn content, and as a solid solution alloy, it has excellent moldability for precision parts. That's true.

Copper alloys for electronic and electrical equipment other than phosphor bronze include spinodal type Cu-Ni-8n alloys and Q=Cu-Be
There are alloys. The former has higher tensile strength than phosphor bronze, but has a low electrical conductivity of 5 to 7% IAGS and poor workability.
Moreover, the latter is very expensive, so its uses are limited.

As an improved alloy of phosphor bronze, Fe%CO, etc. 1 o, 5~2%, O, etc. are added to phosphor bronze for the purpose of improving hot workability.
r, Zr % Ti, V, etc. i 0.2-0.111% added (Jihin 527!'21211), Phosphor bronze with Fe f Q, 50,03-0.09% added (Jihin 527!'21211) 57meg9449) etc. In addition, there is a product in which 005 to 1% Ag is added to phosphor bronze for the purpose of improving corrosion resistance (time opening IJ9〆75)↓17).

(Problems to be solved) When using phosphor bronze Ft for various parts of electronic and electrical equipment,
Soldering is a phenomenon in which the joint strength of parts deteriorates over time, or
A phenomenon in which the plating film such as n1Sn-Pb peels off over time is observed.

These phenomena occur because P in the phosphor bronze diffuses and concentrates at the interface between the phosphor bronze and the solder or near plating film, further embrittling the ε phase, which is a compound of Cu and Sn, that forms at the interface. It is something.

For the peeling of the plating film, a method has been proposed in which the entire amount of Cu or N1 is interposed between the fluorescent bronze and the plating film (Chimae 51〆41222 and Jikai 49〆10g562), but the manufacturing process is complicated. There are problems such as.

Of the above, the aging phenomenon of solder joints is an issue that needs to be solved as soon as possible in the current situation where printed circuit board mounting is transitioning from through-hole mounting to high-density surface mounting in which solder connections are frequently used.

On the other hand, as designs for the efficient use of these parts progress, there is a tendency for members to be subjected to more excessive stress, and NHs,...
It is increasingly desired to develop an alloy that is resistant to stress corrosion cracking even in a corrosive environment where SOx, NOx, etc. are present.

To summarize the points that need to be improved in order for phosphor bronze to be used more efficiently and with higher reliability as a component of electronic and electrical equipment, they are: (1) aging deterioration of solder joints, (2) Sn
, aging deterioration of adhesion of 5n-Pb plating, (3) stress corrosion cracking resistance, (lI>hot workability, (5) moldability.

(6) Mechanical strength, especially springiness and stress relaxation properties, (7)
4 electricity rate etc.

(Means for Solving All Problems) The present invention has been made in view of the above situation, and is a high-strength material suitable for demolishing electronic and electrical equipment that has excellent solder bonding properties, plating adhesion properties, stress corrosion cracking resistance, etc. It concerns conductive copper alloys.

That is, the present invention contains Sn2-8%, P 0.2% or less, 0°0, OO25% or less, Mn 0.01-0.5%, Cr
0.05~α5%, Fe or/and COtα0~
L5%, Zn0.01-5%, B α01-0.1
%, MO, 01-1%, Mg0.01-0.2%, s1
One or two of α0l-05%, T10, 01-0.2chi
It is made of a high strength conductive steel alloy containing a total of 001 to 0.001 to 0.001 to 1.00%, and the balance being copper.

In the present invention, Sn is effective in improving strength, but the reason why the content is limited to 2 to 8% is that if it is less than 2%, the tensile strength and springiness are insufficient, and if it exceeds 8%, the uniform α
This is because it is difficult to form a solid solution, resulting in poor moldability.

P is Fe or Go and Fe5P1FetP%FeP,
Compounds such as CotP and CoP 1GoPs are generated and finely distributed to completely prevent coarsening of crystal grains, improve hot workability, and further improve strength, heat resistance, and stress corrosion cracking resistance. The reason for limiting the total P content to 0.2% or less is 0.
．． This is because if the amount exceeds 2%, P will diffuse and concentrate at the solder or plating interface, reducing solder bonding properties and plating adhesion, and is also harmful to hot workability.

In particular, the P content is 0.0005 to 0.08%, and Fe
It is desirable that the amount is equal to or less than the stoichiometric amount of or/and Go. Fe or/and Go content 2
The reason why O is limited to 5 to 1.5% is that if it is less than 0.05%, the action and effect with P described above will be insufficient, and if it exceeds L5%, the conductivity will decrease significantly and the manufacturing processability and solder bonding will be reduced. This is because the properties and adhesion of plating decrease.

Ol is contained as an impurity, but its counterfeit α0025
% or less is because if O, OO exceeds 25%, not only will the moldability deteriorate significantly, but also the solderability and
This is because plating adhesion deteriorates.

Mn has a deoxidizing effect, and 0! amount? There is a movement to reduce this.

The reason for limiting the content to α01-0.5% is 0.
0.01% or less. This is because it is insufficient to reduce the electrical conductivity to 0.025% or less, and if it exceeds 0.5%, the decrease in electrical conductivity becomes large.

Zn0.01-5%, BO, Oi -0.1%, AH
0.01~1 yen, 1.1g (101~0.2%, Si0
．． 01-0.5%, Ti 0.01-0.2%, or two or more of them are contained in a total of 5% or less, but these elements reinforce the action of the Mn and improve moldability and solderability. ,
Completely improves plating adhesion.

The reason for limiting the content of each element as above is that if the content of each element is less than the lower limit, the above effects cannot be obtained, and if it exceeds the upper limit, the conductivity will decrease significantly and the manufacturing processability will be reduced. This is because the

The reason why the total amount of two or more of these elements is limited to 5% or less is that if it exceeds 5%, the electrical conductivity will decrease significantly and the manufacturing processability will decrease.

Particularly desirable contents of these elements are Zn0.1-1T,
80.03~0.08%, MO05~0.2%, lJg
o, 02-0.07%, 510602-02%, T10
．． 02-01%.

Or improves hot workability, strength, heat resistance, and stress corrosion cracking resistance. Or is more effective than Fe or CO because the amount of solid solution in Gu is smaller. Here, the Cr content i
The reason why it is limited to 0.05 to 0.5% is that if it is less than 0.05%, the above effects cannot be obtained, and if it exceeds 0.5%, the precipitates become coarse and hot workability deteriorates. A particularly desirable Cr content is 0.15-0.14%.

The alloy of the present invention has higher strength when compared with conventional phosphor bronze at the same -Sn concentration, so at the same strength, S
The total n content can be reduced by 0.5 to 2%, and the electrical conductivity can be improved accordingly.

The alloys of the invention can be manufactured by conventional methods. That is, after melting Cuf, adding alloying elements to it and homogenizing it,
An ingot is formed using a water-cooled casting method, then hot rolled, then subjected to intermediate heat treatment if necessary, then cold rolled and processed to the specified dimensions, and further processed by low temperature annealing, tension leveler, tension annealing, etc. It is then finished with the specified material.

When a thin ingot is cast by a continuous strip casting method using a graphite mold or the like, the ingot is directly cold rolled to the predetermined dimensions without hot rolling.

(Example) The present invention will be explained in detail below using examples.

The alloys listed in Table 1 were melted in a graphite crucible in air with a charcoal coating and cast into a 150 x 30 x 300 gourd mold. This ingot was face-faced to remove oxide scale, then hot-rolled at 850°C to a thickness of 8 mm, and then α9
After cold-rolling to a thickness of 0.3 mm, heat-treating at 600°C for 30 minutes, further cold-rolling to a thickness of 0.3 mm, and finally heat-treating at 300°C.
Heat treatment was performed for 15 minutes.

The samples thus obtained were examined for tensile strength, elongation, electrical conductivity, solder joint strength, stress corrosion cracking resistance, and Sn plating adhesion.

The solder joint strength was determined by cutting out a sample f 5 × 5 tar chip, eutectic soldering a hard copper wire with a diameter of 2 fi to it, holding it at 150° C. for 500 hours, and performing a post-pull test.

Stress corrosion cracking resistance is 5■01 according to JISC8306
% I (Hm) A load of A, which is a breaking load, was applied in steam and the time until cracking occurred was measured.

Sn plating adhesion was determined after degreasing and pickling the sample.
After plating 5μ of Ni and holding it at 120° C. for 1000 hours, a close bending test was performed and the bent portion was magnified 10 times with a top microscope to check for peeling of the Sn plating layer.

The bath and conditions for Sn plating are 5nSO+ = 100
? /11 H so, 250r/l, β-naphthol: 1 f/t.

Glue: 2 f/lx bath temperature 16°C, current density:
L5A/drr? It is.

The results are shown in Table 2.

As is clear from Table 2, the products of the present invention (1 to 5) are superior to conventional phosphor bronzes (14, 15) in solder joint strength, stress corrosion cracking resistance, and plating adhesion;ヰ、5
) has even higher tensile strength.

Among the comparative products, the one (6) in which P exceeds the upper limit is inferior in solder joint strength, stress corrosion cracking resistance, and plating adhesion. Lln
In case (7) where lSl is less than the lower limit, excessive OK remains and elongates, resulting in poor solder joint strength and plating adhesion.

Those in which Mn or Fe or CO exceeds the upper limit (8 to 10)
has a large decrease in conductivity.

Items in which Zn exceeds the upper limit of gold and Fe and Go are less than the lower limit (11)
has poor electrical conductivity and stress corrosion cracking resistance. In the case where Mg exceeds the upper limit (6), oxides are incorporated into the steel due to Mg's strong affinity with O8, making it impossible to obtain a sound ingot, resulting in low tensile strength and elongation, and low solder joint strength. Poor plating adhesion.

C→;” In case 03, which exceeds the second limit, the conductivity decreases significantly.

(Effects of the present invention) The alloy of the present invention has superior strength and conductivity compared to conventional phosphor bronze, does not deteriorate over time in terms of solder bondability and plating adhesion, and has excellent stress corrosion cracking resistance. , it produces remarkable effects when applied to lead members or spring members of electronic and electrical equipment.

Claims (1)

[Claims] Sn2~8wt%, P0.2wt% or less, O_20.0
025wt% or less, Mn0.01-0.5wt%, Cr
0.05-0.5wt%, 0 Fe or/and Co
．． 05-1.5wt%, Zn0.01-5wt%, B0
．． 01-0.1wt%, Al0.01-1wt%, Mg
0.01-0.2wt%, Si0.01-0.5wt%
, 0.01 to 0.2 wt % of Ti in a total amount of 0.01 to 5 wt %, and the balance is copper.