Compositions – Electrically conductive or emissive compositions – Metal compound containing
Reexamination Certificate
2002-10-22
2004-02-10
Gupta, Yogendra N. (Department: 1751)
Compositions
Electrically conductive or emissive compositions
Metal compound containing
C252S500000, C252S506000, C252S511000, C252S514000, C423S297000, C501S021000, C501S015000, C501S096100, C106S001140, C106S733000
Reexamination Certificate
active
06689296
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a conductive paste which is printed on a glass substrate and baked to form defogging heat wires for automobile windows.
2. Description of the Related Art
Automobile windows are provided on the surface thereof with conductive wires for preventing the window from fogging and which are formed by printing and baking a conductive paste. The conductive wires heat up when energized and, thus, prevent the automobile window from fogging. Also, the regions of the window where the conductive wires are disposed have a dark color so as to be nice to look at when viewed from the outside of the automobile.
Such a conductive paste generally contains an additive for darkening the external appearance of the window glass. As this additive, V, Mn, Fe, Co and their oxides (Japanese Unexamined Patent Application Publication No. 5-290623) and Cr, Rh and their oxides (Japanese Unexamined Patent Application Publication No. 9-92028) are known.
However, these additives have problems of (1) making the color of the conductive wire regions of the window nonuniform due to the formation of a low melting point salt resulting from a reaction with part of the silver contained in the conductive paste; (2) degrading solder wettability due to an oxide coming to the surface of conductive wires together with glass after baking, and thus reducing bonding strength of lead wires; (3) being likely to vary the valence of transition metals during baking and, thus, to produce harmful substances; and (4) increasing cost when Rh is used.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a conductive paste for defogging heat wires of an automobile window which uniformly darkens the conductive wire regions of the window, does not produce any harmful substances and ensures sufficient bonding strength of lead wires.
To this end, the present invention is directed to a conductive paste for defogging heat wires of automobile windows. The conductive paste contains a silver powder, a molybdenum compound, a glass frit and an organic vehicle.
According to this composition, the conductive wire regions of the window viewed from the outside of the automobile can efficiently be darkened. Also, by adjusting the content of the molybdenum compound, the specific resistance of the conductive wires can be controlled at a desired level.
Preferably, the molybdenum compound is molybdenum silicide or molybdenum boride.
Preferably, the molybdenum compound content is in the range of about 0.1 to 13 parts by weight relative to 100 parts by weight of the silver powder.
REFERENCES:
patent: 5470506 (1995-11-01), Tanigami et al.
patent: 01-080008 (1989-03-01), None
patent: 64-081106 (1989-03-01), None
patent: 05-290623 (1993-11-01), None
patent: 06-204511 (1994-07-01), None
patent: 09-092028 (1997-04-01), None
patent: 10-326522 (1998-12-01), None
Adachi Fumiya
Nagai Akira
Dickstein Shapiro Morin & Oshinsky LLP.
Gupta Yogendra N.
Murata Manufacturing Co. LTD
Vijaykumar Kallambella M
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