Coating processes – Electrical product produced – Resistor for current control
Reexamination Certificate
1999-04-29
2001-02-13
Talbot, Brian K. (Department: 1762)
Coating processes
Electrical product produced
Resistor for current control
C427S103000, C427S282000, C101S127100, C101S128100, C101S129000
Reexamination Certificate
active
06187372
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to microcircuits and more particularly to large area thick film resistors.
BACKGROUND OF THE INVENTION
Today's complex integrated circuits typically employ many instances of resistors on a single substrate. These resistors come in varying sizes. Hybrid circuitry generally uses thick film resistors with geometries greater than 30 mils. Other applications of hybrid circuitry and other circuitry may use smaller resistors which provide for a more cost-effective circuit since less area on the ceramic is used.
Techniques, such as the one described in “Power Considerations in Small Geometry Thick Film Resistors,” Andy London et al., Heraeus Technical Paper, 1999, which is incorporated herein by reference for all that it teaches, have been developed to improve upon small thick film resistors. However, absent in the art is a technique to improve upon the printing of thick film resistors. One problem which is encountered while printing thick film resistors is commonly referred to as “screen sag” in which the center portion of the resistor is scooped out by the squeegee.
SUMMARY OF THE INVENTION
The present invention provides large area, thick film resistors with improved predictability and uniformity and method for producing same. “Tent poles” are employed during the printing of the large area resistors to prop up the screen mesh to ensure the resultant resistor does not have a scooped out center portion.
REFERENCES:
patent: 4242401 (1980-12-01), Mitani et al.
patent: 4958560 (1990-09-01), Collins
Casey John F
Dove Lewis R
Johnson Rosemary O
Agilent Technologie,s Inc.
Murphy Patrick J.
Talbot Brian K.
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