Stock material or miscellaneous articles – Structurally defined web or sheet – Including aperture
Reexamination Certificate
1999-04-28
2003-02-11
Watkins, III, William P. (Department: 1772)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including aperture
C428S901000, C428S702000, C428S701000, C428S699000, C428S698000, C428S428000, C428S426000, C428S210000, C428S209000, C264S614000, C264S673000, C264S672000, C174S258000, C174S259000, C156S089120
Reexamination Certificate
active
06517924
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laminated body and a method for producing the same. More particularly, the present invention relates to a laminated body in which a part of the layers are in a sintered state and the contraction thereof due to baking is suppressed, and a method for producing the same.
2. Description of the Related Art
In compliance with the recent trend of making chip components compact and lightweight, circuit boards for packaging these components are also required to be compact and lightweight. A glass-ceramic multilayer circuit board is effective for responding to the requirements described above because a highly integrated wiring is made possible with the glass-ceramic multilayer circuit board while making the board thin. However, such glass-ceramic multilayer circuit boards are produced through a baking step and usually accompanied by contraction during the sintering process so that a dimensional distribution of, for example, about ±0.5% is inevitable using the currently available technology. Such dimensional distribution becomes more evident in a glass-ceramic multilayer board having a cavity for housing appropriate electronic components.
Japanese Unexamined Patent Publication No. 5-102666 or Japanese Unexamined Patent Publication No. 7-330445 proposes, for example, a method for producing a glass-ceramic multilayer circuit board with a high dimensional precision, and Japanese Unexamined Patent Publication No. 6-329476 proposes, for example, a method for producing a glass-ceramic multilayer circuit board having a cavity, wherein green sheets which are not sintered at the sintering temperature of a glass-ceramic molded body are laminated on one side or on both sides of the glass-ceramic molded body and, after baking the green sheet in the laminated state, powder layers originating from such green sheet are removed.
However, according to the method for producing the glass-ceramic multilayer circuit board as described above, a complicated process is required for removing the powder layers originating from the green sheet after baking, and it becomes impossible to previously form a conductive layer on the surface of the glass-ceramic molded body before baking in order to bake the conductive layer simultaneously with the glass-ceramic molded body. Another problem is that surface roughness of the glass-ceramic multilayer circuit board after removing the powder layer originating from the green sheet becomes large.
Japanese Unexamined Patent Publication No. 9-266363 discloses a method comprising the step of sintering merely the glass-ceramic layer by baking the glass-ceramic layer in a laminated state with an alumina layer, allowing the glass component contained in the glass-ceramic layer to permeate into the alumina layer while the alumina layer remains to be non-sintered state, thereby allowing the alumina layer to be solidified. In this case, the glass permeating from the glass-ceramic layer is never distributed throughout the entire area of the alumina layer, but instead the surface is polished simultaneously with removing the non-solidified portion of the alumina layer and a conductive film for the circuit pattern is formed after the foregoing removing and polishing steps.
Accordingly, while it is possible to diminish surface roughness by the removing and polishing steps according to the conventional art, an independent removing step after the baking step as in the foregoing conventional art is also required, making it impossible to obtain the conductive film to be formed on the surface of the circuit board by baking the film simultaneously with the glass-ceramic layer.
Japanese Unexamined Patent Publication No. 5-136572 discloses a method, as in the foregoing conventional art, comprising the step of laminating green sheets that are not sintered at the baking temperature of the glass-ceramic on one face or on both faces of the glass-ceramic molded body, followed by sintering merely the glass-ceramic molded body. In this method, the powder layer originating from the non-sintered green sheet is filled with a resin.
According to the conventional arts, a separate step of filling the resin is required, although the step of removing the non-sintered powder layer has been excluded.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a laminated body that does not especially require post-treatment steps such as a removing step and resin filling step after the baking step to attain a state that can be offered for use, and a method for producing the same.
One preferred embodiment of the present invention provides a laminated body, comprising:
a first sheet layer comprising an aggregate of a first powder, at least a part of the first powder being in a sintered state;
a second sheet layer disposed so as to make a contact with the first sheet layer and comprising an aggregate of a second powder, the second powder being in a non-sintered state; and
the first powder and the second powder being solidified to each other by allowing a part of the first sheet layer material to diffuse or to flow into the second sheet layer.
In the above described laminated body, the part of the first sheet layer material may diffuse or flow into the entire area of the second sheet layer and the overall second powder is solidified with the first sheet layer material.
In the above described laminated body, at least a part of the first powder may have a melting point lower than the sintering temperature of the second powder.
In the above described laminated body, the aggregate of the first powder may contain a glass material.
In the above described laminated body, the glass material may comprise a material made to be a glassy state by melting through baking.
In the above described laminated body, the glass material may comprise a nucleated glass material.
In the above described laminated body, the aggregate of the first powder may further comprise a ceramic material.
In the above described laminated body, the aggregate of the first powder may comprise a mixed material comprising at least one of anorthite nucleated glass, borosilicate glass and corgelite system nucleated glass and alumina.
In the above described laminated body, the aggregate of the second powder may comprise a ceramic material.
In the above described laminated body, a plurality of the first sheet layers may be laminated via the second sheet layer.
In the above described laminated body, a pair of the first sheet layers respectively positioned at each side of the second sheet layer may have substantially the same thickness with each other.
In the above described laminated body, a plurality of the second sheet layers may be laminated via the first sheet layer.
In the above described laminated body, a conductive film may be provided on the surface and/or inside of the laminated body, so that thereby the first sheet layers, the second sheet layers and the conductive film constitute a circuit board.
In the above described laminated body, the second sheet layer may be thinner than the first sheet layer.
In the above described laminated body, a cavity may be provided so as to allow its opening to be positioned along at least one of the principal faces of the laminated body.
Another preferred embodiment of the present invention further provides a method for producing a laminated body comprising the steps of:
a first step for preparing a raw laminated body provided with a first sheet layer being in a raw state comprising a first powder and a second sheet layer being in a raw state disposed so as to make contact with the first sheet layer and comprising a second powder not sintered at a temperature capable of sintering at least a part of the first powder; and
a second step for baking the raw laminated body at a predetermined temperature so as to allow at least a part of the first powder to be sintered and the second powder to be not sintered, along with solidifying the first sheet layer and the second sheet layer to each other by allowing a par
Kameda Hirokazu
Nakao Shuya
Tanaka Kenji
Dickstein Shapiro Morin & Oshinsky LLP.
Murata Manufacturing Co. Ltd
Watkins III William P.
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