JPS63317635A - Copper alloy for electronic equipment and its production - Google Patents

Abstract

PURPOSE:To improve electric conductivity, strength, and isostatic workability, by specifying the respective contents of Cr, Ni, Co, Sn, P and O2 in copper. CONSTITUTION:An alloy ingot having a composition consisting of, by weight, 0.05-0.85% Cr, 0.05-0.4% Ni or Co, 0.02-0.27% Sn, <=0.15% P, <=0.005% O2, and the balance Cu is used. This alloy ingot is hot worked at >=600 deg.C, cooled down to 450 deg.C at >=1 deg.C/sec cooling rate, and then subjected to cold working including single or more heat treatments so as to be formed into the desired copper alloy. This copper alloy has superior electric conductivity and strength and also high-degree isostatic press formability and is particularly suitable for compact and highly concentrated semiconductor frames. When Cr content is below the lower limit, strength is insufficient, and, when it exceeds the upper limit, workability is deteriorated. When Ni or Co is below the lower limit, strengthening is insufficient, and, when it exceeds the upper limit, electric conductivity is deteriorated. When Sn is below the lower limit, strengthening-, elomgation-, and workability-improving effects cannot be produced, and when it exceeds the upper limit, electric conductivity is remarkably deteriorated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a copper alloy for electronic equipment used in electrical equipment connectors, switch springs, terminals, semiconductor lead frames, lead wires, etc., and a method for manufacturing the same. The present invention provides a copper alloy suitable for use in small, high-density semiconductor lead frames.

[Conventional technology]

Generally used for electrical equipment connectors, switch springs, terminals,
Cu-8n-based phosphor bronze is used for semiconductor lead frames, lead wires, and the like. Although this alloy has good strength and workability, it has a low electrical conductivity of 70 to 25% lAC3, so it has the disadvantage of poor electrical properties and heat dissipation properties. Therefore, C1, l-Fe system (7)C is used in semiconductor lead frames.
194 (CLJ -2,4wt%Fe ~0.12w
t%7n-P alloy) (hereinafter wt% is abbreviated as %) and C19
5(Cu-1,5%Fe-o, a%Co~0.6%S
n-)) alloy) is used. This alloy has a strength of 45-55 Kg i'mrA and a conductivity of 50-65%l.
The characteristics of AC3 are shown.

In recent years, there has been significant progress in the miniaturization and density of electronic decovers, and the properties of the required alloys have also improved.

This trend is most noticeable in semiconductors, which have come to occupy an important position in industry. That is, in mass-produced plastic molded semiconductors, the C194 and C195 are D.
It is used in large quantities in IP type frames with 700m11 pitch two-way leads.

(Problems to be Solved by the Invention) In response to this, SOP and FP are new surface-mount semiconductor packages that can be made smaller.

PLCC is strongly required. PLCC is 50m11
It uses Pituji's frame with four-way leads, and the SOP and FP are also 50m long (2 with fine pitch).
Surface mounting using directional leads enables higher density mounting over a wider area than conventional DIP. For new electronic and mechanical copper alloy parts such as these, a balance between strength and workability is required at the same time as further improvement in electrical conductivity. What is even more important is the isotropy of the mechanical properties, and the difference in properties depending on the rolling direction and width direction of the strip, especially the processing strength and 1) ■, is critical for lead frames such as PLCG that require high precision. It becomes a defect.

The above-mentioned phosphor blue, copper, and Cu-["e-based alloys cannot satisfy the above-mentioned required characteristics, and therefore C150 (Cu ~
0.1%Zr alloy) and Cu-2%5n~0.1%Or alloy are used, but the former shows high conductivity of about 90%lAC3, but the strength is about 40kg1-, and the latter Although it shows a strength of about 55 Kg/-, the electrical conductivity is 30~
It is as low as 40% lAC3.

As described above, copper alloys for electronic devices are required to have excellent electrical conductivity and strength, as well as high isodirectional workability, that is, press formability, and are also required to have high reliability for surface mount components. There is also a need to improve the solder joint strength and the adhesion of the opening scale, both of which are important for this purpose.

(Means for Solving the Problems) In view of this, and as a result of various studies, the present invention has developed a copper alloy for electronic devices that satisfies the above-mentioned properties and a method for producing the same.

That is, the steel alloy of the present invention contains 0.05 to 0.85% cr, N
i or Co 0.05-0.4%, 3n 0.02-0
, 27%, P 0.15% j

In addition, in the production method of the present invention, cr is 0.05 to 0.85%, N
i or CO 0.05-0.4%, 3n 0.02-0
．． 27%, contains 0.15% or less of P, and contains 0.02.
After hot working an alloy ingot consisting of 0.005% or less and the remainder CU at 600°C or higher, it is heated at 1°C/sec to 450°C or lower.
It is characterized in that it is cooled at a rate of -F or less, and then subjected to cold working including at least one heat treatment.

[Effect]

According to the present invention, the electrical conductivity is 80-85% lAC3, and the strength is 45%.
An alloy member with isotropic homogeneous mechanical properties of ~55/- is obtained. The reason why the alloy composition is limited as described above is as follows.

The reason for limiting the Cr content to 0.05 to 0.85% is that Cr precipitates in the matrix and does not maintain high conductivity. If it is less than 0.85%, the strength will be insufficient, and if it exceeds 0.85%, the precipitation of Cr will be excessive, impairing the manufacturing process and the workability of the product. It is desirable to set the Ni or Co content to 0.2 to 0.5%.The reason why the Ni or Co content is limited to 0.05 to 0.4% is that both of these are intended to further strengthen the alloy member. In addition, in the coexistence of P, N + P, COP compounds are composed to effectively strengthen the steel, and more importantly, the dispersibility of Cr precipitated particles is improved to improve workability.
If it is less than 0.05%, a sufficient effect cannot be obtained, and if it exceeds 0.4%, the conductivity will necessarily decrease by 8 degrees. Sn-containing tT
The reason why m is limited to 0.02 to 0.27% is because 3n is a solid solution element that strengthens the alloy member, improves elongation and workability, and also suppresses the quenching sensitivity of Cu-Cr alloys. If the content is less than 0.02%, the above effect cannot be achieved in practice, and if it exceeds 0.27%, the conductivity will drop significantly and it will also be harmful to the adhesion of oxide scale. It is.

Furthermore, the reason why P is contained within the range of 15% or less is that P forms a compound with Cr, Ni or CO, is uniformly dispersed and hardens by precipitation, or acts as a deoxidizing agent. This facilitates the melting and fabrication of alloys. However, if the phase content exceeds 0.15%, not only will the electrical conductivity decrease, but there will also be problems such as the formation of coarse compounds in the ingot state. In addition, the reason why the 02 content is limited to 0°005% or less is because if the content exceeds 0.005%, it not only generates oxides and Cu2O and reduces workability, but also oxidizes as well as excessive Sn. This is because scale adhesion and soldering impair properties specific to electronic devices, such as performance, and the content is desirably 0.003% or less.

The alloy member of the present invention is produced by hot working an alloy ingot having the above-mentioned composition range at a temperature of 600°C or higher, preferably 700 to 900°C.
Cool down to 450'C or less at a rate of 1°C/SeC or more. It is produced by subjecting this to cold working including at least one heat treatment. In this manufacturing process, the reason for cooling at a rate of 1°C/SeC or higher until at least 450°C after hot working is to keep a considerable portion of Cr in solid solution and prevent coarse precipitation of Cr, etc. If the cooling rate is less than 1°C/SeC, coarse precipitates such as Cr will occur, which will not only reduce the strength but also make it impossible to obtain isotropic properties. Next, at least one heat treatment (450 to 650
Cold working including cold working (℃) is performed due to the effect of cold working strain, preferably 70% or more.
This is to form finely dispersed precipitates. However, the reason why the first heat treatment temperature is set to 450 to 650°C is that if it is lower than 450°C, precipitation will take a long time, and if it exceeds 650°C, a part of Cr will be solid-dissolved again.

The material that has been subjected to the first heat treatment is then cold worked again to improve its mechanical properties through work hardening and to achieve desired dimensions. The intermediate heat treatment can also be repeated as necessary. 1st heat 51! The processing rate after X-processing must be kept below 95%.
In particular, Cr is deformed and oriented in the processing direction and has directionality.

In this way, the present invention was achieved by combining the alloy composition and processing conditions, and uniform and fine precipitation and dispersion of Cr are the first conditions for electrical conductivity, strength, workability, and isotropy.
The coexistence effect of Cr permeability with Sn, Ni, Co, etc. of the present invention is made possible by the restriction of the cold working rate as well as the hot working process and heat treatment. Furthermore, for electronic devices, especially high-precision lead frames for semiconductors that will become increasingly finer and denser in the future, in addition to the above characteristics, oxide scale adhesion and semi-EE bonding properties are important, and the members of the present invention fully satisfy these requirements. It is something that can be done.

Further, although the alloy composition of the member of the present invention is the above-mentioned composition and the remainder is substantially Cu, the presence of ordinary impurities does not have any detrimental effect on the properties. Furthermore, trace amounts of additive elements that are normally used to improve the properties of copper alloys, such as Ti, zr, Mg, Aq,
It is also effective to add Ca, Zn, Mn, B, Fe, etc., and these are caused by effects such as crystal refinement, strengthening, and deoxidation, and a sufficient effect is achieved at 0.5% or less. .

[Example] An alloy having the composition shown in Table 1 was water-cooled and then cast at 850°C.
Heat to a thickness of 5.0. After hot rolling, the finishing temperature and cooling rate after rolling were measured.

Next, the surface was milled to a thickness of 4.6a, and this was cold rolled to a thickness of 0.858. Thereafter, a first heat treatment was performed, followed by cold rolling, a portion was subjected to an intermediate heat treatment to obtain a desired thickness, and a portion was subjected to low-temperature annealing to produce a copper alloy material for electronic devices. Table 2 shows the processing conditions.

Next, the electrical conductivity, tensile strength, and elongation of the above members were measured, and the workability, solder joint strength, and oxide scale adhesion 11 were also examined. These results are compared to the conventional 0570 (C
u-5, 2% 3n~0.12% P alloy, thickness 0.2M>
Table 3 shows a comparison between C195 and C195 (thickness 0.25 mm).

Regarding workability, bending is performed using a bending tester that combines a 90° V-groove die with punches with various tip radii (R), and the presence or absence of micron cracks at the bent part is examined with a microscope to determine the minimum bending radius (R). The ratio (R/l) between and plate thickness (1) was determined. In addition, the solder joint strength was determined for the brass wires that were eutectic soldered to a certain width, and the soldering was performed at the initial stage and at 150°C for 500 hours.
It was determined by a tensile test after aging.

Furthermore, regarding the adhesion of oxide scale, a cellophane tape peeling test was conducted on the samples heated at 450° C. for 1 minute and 60 minutes.

As is clear from Tables 1 to 3, the alloy of the present invention No.
1 to 7 have electrical conductivity of 80 to 85%lAC3 and tensile strength of 45 to 85%.
55 to 3/7 and elongation of 6 to 70%, conventional material rci
Le c195 (No, 13>, C570 (No, 14>
Compared to the above, it can be seen that it is overall superior. That is, nOI
It can be seen that R/l, which indicates the stability and isotropic tradeability, is small, there is little abnormal decrease in solder joint strength, and the adhesion of oxide scale is excellent.

In contrast, comparative alloy No. lacking Ni or 3n.

6, the homogeneity decreased, and Cr, Ni or Co,
Comparative alloy No. containing excessive 3n or P.

7 to 70'c not only lowers the electrical conductivity and isotropic homogeneity, but also lowers either the solder joint strength or the adhesion of the oxide scale. Furthermore, even for alloys within the alloy composition range of the present invention, comparative alloy NO,11 had a slow cooling rate after hot rolling, and the processing rate before the first heat treatment was small and the processing rate after the first heat treatment was excessive. It can be seen that the comparative alloy N 0.12 has poor isotropic tradeability.

[Effects of the Invention] As described above, according to the present invention, characteristics suitable for electronic equipment, especially the semiconductor lead frame that occupies the center thereof, can be achieved in a poetic manner, and the electronic equipment can be compact. : It has excellent industrial effects, such as having optimal performance as a one-density surface-mount lead frame.

Claims (4)

[Claims] (1) 0.05 to 0.85 wt% Cr, Ni or Co
0.05 to 0.4 wt%, Sn 0.02 to 0.27
A copper alloy for electronic devices, containing 0.15 wt% or less of P, 0.005 wt% or less of O_2 content, and the balance being Cu. (2) 0.05 to 0.85 wt% Cr, Ni or Co
0.05 to 0.4 wt%, Sn 0.02 to 0.27
wt%, containing 0.15 wt% or less of P, O_2 content of 0.005 wt% or less, and the balance consisting of Cu.
After hot working at 00°C or higher, 1°C/1°C down to 450°C or lower
A copper alloy for electronic devices and a method for producing the same, characterized in that the copper alloy is cooled at a rate of 1.5 seconds or more, and then subjected to cold working including at least one heat treatment. (3) The method for producing a copper alloy for electronic devices according to claim 2, wherein the first heat treatment is performed at 450 to 650°C. (4) Claim 2 or 3 states that the cold working rate before the first heat treatment is 70% or more, and the total cold working rate after the first heat treatment is 95% or less. A method for producing copper alloys for electronic devices.