Metal treatment – Stock – Ferrous
Patent
1992-01-06
1993-11-23
Yee, Deborah
Metal treatment
Stock
Ferrous
148328, 148409, 420 94, 420459, C22C 3808, C22C 1903
Patent
active
052640507
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a Fe-Ni based alloy having a small thermal expansion coefficient.
BACKGROUND ART
A Fe-Ni based alloy, e.g., 42 wt % Fe-Ni, 29 wt % Ni, 17 wt % Co-Fe has been hitherto known as an alloy having a low thermal expansion. This kind of Fe-Ni based alloy has been used in industrial application fields where a metallic material having a low thermal expansion coefficient, e.g., a material for a lead frame used for producing an integral circuit package or the like, a material for a part constituting a cathode ray tube for a Braun tube, a material for a part constituting an electron tube, a sealing material are required.
Firstly, description will be provided below as to, e.g., a material for a part constituting a cathode ray tube. A plurality of electrodes for converging or deviating an electron beam emitted from a cathode are arranged in the cathode ray tube. With respect to a material required for constituting the electrodes, it is an essential condition that the material have a small thermal expansion coefficient in order to assure that an electron beam is emitted without any undesirable disturbance due to thermal expansion during the working of the cathode ray tube. For this reason, the foregoing kind of Fe-Ni based alloy is employed. In addition, with respect to a shadow mask to be arranged in the cathode ray tube, the same kind of Fe-Ni based alloy is employed for the same reason as mentioned above.
However, although a conventional Fe-Ni based alloy satisfactorily meets the requirement for a low thermal coefficient, it has the following drawbacks. Accordingly, many strong requests have been raised so as to obviate these drawbacks.
One of the drawbacks inherent to the conventional Fe-Ni based alloy is that a bur having a high height results during a punching operation performed by actuating a press machine. When a material having a bur having a high height formed in a punching region is employed for a part constituting a cathode ray tube, there arises a malfunction and electron beam properties are adversely affected. This problem likewise appears when the foregoing kind of material is employed for a part constituting an electron ray tube. In addition, in the case where this material is employed for forming a lead frame, if a bur has a high height, there appear problems that the number of bending the lead pin is reduced, and moreover, a running life of a press die is shortened. Also with respect to the sealing material, when a bur is located, e.g., in the sealing region, cracks readily extend from the sealing region, whereby properties of the part are affected adversely.
In recent years, as semiconductor elements are integrated at a higher density, it is increasingly required that each lead frame is designed to have a thinner thickness while using a number of pins. In connection with the foregoing current status, a material for forming a lead frame, composed of the conventional Fe-Ni based alloy, has problems that a fine pattern can not be formed with excellent reproductivity, and moreover the material has insufficient mechanical strength and heat resistance. Not only with the material for forming a lead frame but also with a material for forming a part constituting a cathode ray tube, when the material for forming a part constituting a cathode ray tube has insufficient mechanical strength and heat resistance, it is remarkably softened by heat treatment carried out before an assembling operation. This leads to problems that handling capability is degraded and undesirable deformation is liable to occur during the assembling operation.
Generally, the conventional Fe-Ni based alloy has a large quantity of dissolved gas. For this reason, when it is employed as a material for forming a part constituting a cathode ray tube or a material for forming a part constituting an electron tube, there appear problems that a quantity of gas release in a vacuum is increased and a degree of vacuum in the cathode ray tube or the electron ray tube is lowered, resulting in properties
REFERENCES:
patent: 3573897 (1971-04-01), Wache
patent: 5059257 (1991-10-01), Wanner et al.
Nakashima Nobuaki
Sugai Shinzo
Watanabe Eiichi
Kabushiki Kaisha Toshiba
Yee Deborah
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