Compositions – Electrically conductive or emissive compositions – Free metal containing
Reexamination Certificate
2000-06-30
2003-07-22
Kopec, Mark (Department: 1751)
Compositions
Electrically conductive or emissive compositions
Free metal containing
C252S062540, C252S062550, C336S015000, C336S020000, C338S302000, C174S11000P, C174S257000
Reexamination Certificate
active
06596200
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electronic material composition comprising a specific resin component, to electronic components to be manufactured from the employment of such an electronic material composition, and to the using method of such an electronic material composition.
Curable resins such as epoxy resin are employed as an important component in an electronic material composition which may or may not be mixed with a powdery electronic material such as ferrite powder or metallic powder in the employment thereof. Such electronic materials comprising a curable resin or a powdery electronic material are extensively employed mainly as a material for the manufacture of electronic components, e.g. as a molding material, a coating material, an electrode material, a bonding material, etc.
More specifically, the electronic materials can be employed as an electronic material for the following end-uses (1) to (5).
(1) As for the usage as a molding material of the electronic materials, they can be employed as a material on the occasion of manufacturing the core of wound chip coil for instance. In this case, ferrite powder is granulated together with a resin component and other components as required to obtain granules, which are then dry-molded into a rod like configuration and subjected to a curing treatment. The cured body thus obtained is then subjected to a cutting work to obtain a core whose both ends are provided with a flange. The same procedure can be also applied to the manufacture of the spool of air-core coil though the procedure involves no cutting work in this case. There is also known a so-called working-less manufacturing method wherein ferrite powder is wet-mixed with a resin component and a solvent to obtain a composition which is then molded by means of injection molding for instance to form a molded body, the molded body being subsequently cured.
(2) As for the usage of the electronic material as a coating material, there are four cases (a) to (d) as set forth below.
(a) The electronic material can be employed as an outer packaging material in such a manner that after a winding is applied to the aforementioned core, the resultant coil is coated with the electronic material.
(b) The electronic material can be employed as an electromagnetic shielding material covering the surface of a casing housing an electronic component. In this case, magnetic material powder is mixed with a resin component to obtain a mixture which is then molded into a sheet, a plurality of which are then simply adhered to each other so as to cover the surface of the casing. There is also known a case wherein the casing itself is constituted by a molded body molded from a mixture comprising metallic powder and a resin component.
(c) The electronic material can be employed as a covering material for a connecting cable of a digital video camera, a personal computer, a printer, etc. In this case, a resin component is turned into a molten state and then, extruded together with the cable.
(d) The electronic material can be employed as a covering material for covering the entire surface, including an electronic component, of a printed wiring board having an electronic component mounted thereon.
(3) As for the usage as an electrode material of the electronic materials, they can be employed as a conductive paste containing a glass frit and silver powder for instance, the paste being coated and then, baked to form an external terminal electrode of a chip component. There is also known a case wherein a conductive paste obtained through the mixing of conductive powder with a resin component and a solvent is coated on a chip component and then, baked to form an external terminal electrode likewise.
(4) As for the usage of the electronic material as a bonding material, there are two cases (a) and (b) as set forth below.
(a) The electronic material can be employed as a solder for soldering a chip component for example onto the soldering land of a printed wiring board.
(b) As in the case of manufacturing an LC laminated composite electronic component for instance, the electronic material can be employed as an adhesive material, i.e. as an interconnecting sheet in bonding different kinds of sheets with each other, for instance in a process wherein a green sheet laminate consisting of the same kind of material is laminated with another green sheet laminate consisting of the same kind of another material differing from the first mentioned material to form a composite laminate body, which is then baked to form an LC element. Namely, in this case, these green sheets can be formed of an electronic material composition wherein ferrite powder or dielectric material powder is wet-mixed with a resin and a solvent.
(5) As for the usage as a filler of the electronic materials, they can be employed for filling a joint portion in a situation wherein the wall of building is to be formed by joining electromagnetic shielding boards, panels or tiles to each other.
In relative to the aforementioned end-use (1), there is an increasing demand for the miniaturization of core in accordance with the recent trend to further miniaturize an electronic component. However, as the core becomes smaller, the rigid and fragile nature of the ferrite material becomes more prominent, thus making it difficult to exercise a fine working of the core. As a result, an off-specification product tends to generate, thus deteriorating the yield of the core. In the case of the core which is injection-molded using an electronic material composition prepared through a wet-mixing also, the toughness of core is insufficient. From a reflow soldering test wherein these worked or molded products are subjected to a thermal stress in the soldering step, these worked product as well as molded product are found accompanied with a problem in terms of strength.
In relative to the aforementioned end-use (2)(a), the conventional outer packaging material is accompanied with a problem in the mounting operation of so-called bulk component wherein individual component is picked up by means of an adsorption nozzle from an aggregate consisting of a large number of chips of the same kind and transferred so as to mount it at a predetermined region of a printed wiring board, because the outer packaging material is so rigid and hardly deformable that a gap tends to be generated between the adsorption nozzle and the surface portion of the outer packaging material being adsorbed, thus making it difficult for the adsorption nozzle to pick up the individual component due to slipping between them. Namely, a problem of mis-mount tends to be raised in picking up individual chip component from a large number of chips of the same kind. With a view to minimize this mis-mount, there has been conventionally proposed to improve the accuracy in configuration of the component. However, such a countermeasure is limited in terms of yield.
In relative to the aforementioned end-use (2)(b), when the configuration of casing includes a complicatedly deformed portion such as a complicatedly bent portion or a fine recessed and projected portion, it is difficult to closely adhere electromagnetic shielding sheets onto the wall of the casing. As a result, a sufficient electromagnetic shielding effect may not be ensured.
In relative to the aforementioned end-use (2)(a) and (2)(b), due to a thermal stress resulting from a difference in linear expansion coefficient between the coating material and the surface to be coated, the adhesion plane may be peeled off or a damage such as cracking may be generated in the coating material.
In relative to the aforementioned end-use (2)(c), since the coating material is formed of a resin material, the electromagnetic wave generated from the current flowing through the conductive wire of cable is allowed to radiate into the ambient atmosphere. As a result, the electronic instruments disposed around the cable would be badly affected by the electromagnetic wave, so that it is impossible to suppress so-called radiant noise which may become a
Iri Kinya
Ito Mitsuyoshi
Ogawa Hideki
LandOfFree
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