Metal treatment – Stock – Copper base
Patent
1995-10-30
1998-10-20
Ip, Sikyin
Metal treatment
Stock
Copper base
148436, 148682, 148685, C22C 906
Patent
active
058241671
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to beryllium-copper alloys used as electrically conductive spring materials for lead frames, terminals, connectors, relays, switches, jacks and the like, of which such properties as strength, workability and stress-relaxation are important, and a method for producing the same.
BACKGROUND ART
Beryllium-copper alloys containing 0.2 to 0.3% by weight of Be in copper have been known heretofore as electrically conductive spring materials and disclosed in Japanese Patent Examined Publication No. 4-53936 by the present applicant. As such beryllium-copper alloys, there are aging materials of which an aging treatment is performed by users, and mill-hardened materials of which aging treatment have been applied before shipping.
Recently, due to an enhanced miniaturization of electronic parts, higher strength is required also for beryllium-copper alloys. The materials to be obtained are disclosed in JIS C 1720 (Be 1.8 to 2.0% by weight).
However, in these aging materials of such beryllium-copper alloys, there have been disadvantages that deformation is likely to occur during aging treatment and also setting up of treating conditions is difficult due to narrow tolerance of aging treatment conditions. Therefore, there has been a problem that it is not necessarily easy to attain the desired characteristics by aging treatment at the user's side. Also, in the conventional mill-hardened material of beryllium-copper alloys, there have been problems that a sufficient workability cannot be obtained and, in particular, bending workability is poor in a direction perpendicular to the direction of rolling. Further, as to heat resistance that can be regarded as an index of long-term reliability, there has been a problem that stress-relaxation ratio is large, Incidentally, the stress-relaxation ratio is a value indicating reduction Of spring properties for a long period of time and the measuring method thereof is regulated in EMAS (Japan Electronic Manufacturers Association Standard)-3003 as "Testing Method of Stress-Relaxation by Bending of Spring Materials". According to this standard, the stress-relaxation is defined as a phenomenon that the stress generated in materials under a constant strain decreases slowly with a lapse of time.
DISCLOSURE OF THE INVENTION
The present invention has been developed to address above-mentioned conventional problems. It is an object of the invention to provide a beryllium-copper alloy which is excellent in strength as a matter of course, which can be used as an aging material having a wide tolerance of the aging treatment conditions, i.e., flexible treatment conditions so as to reduce the burden at the user end by making deformation at the aging treatment difficult, and which can be also used as a mill-hardened material having excellent workability and heat resistance. It is a further object of the invention to provide an advantageous method for producing the same.
According to the present invention, there is provided a beryllium-copper alloy excellent in strength, workability and heat resistance, having a composition containing weight, weight, intermetallic compound NiBe or/and CoBe in the range of 0.20 to 0.90% by weight, and at least 45% thereof being present as fine particles having a diameter of 0.1 .mu.m or less.
Also, the present invention provides a method for producing a beryllium-copper alloy which is excellent in strength, workability and heat resistance, and which comprises subjecting to hot working and subsequent cold working a cast material having a composition containing weight, weight, material to a solution treatment at a temperature of 800.degree. C. or higher, cooling at a rate of 20.degree. C./s or more between the temperature range of at least 800.degree. C. to 600.degree. C., subsequently subjecting the material to finishing working of 5 to 40%, and then applying aging treatment to the material at a temperature of 300.degree. to 460.degree. C.
In the present invention, strength, workability and heat resistance to be attaine
REFERENCES:
patent: 2136212 (1938-11-01), Hensel et al.
patent: 2400566 (1946-05-01), Misfeldt
patent: 4792365 (1988-12-01), Matsui et al.
Hiramitsu Hiroyuki
Ishiguro Yoshihisa
Ishikawa Shuhei
Yashiro Kazumasa
Ip Sikyin
NGK Insulators Ltd.
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