Coating processes – Solid particles or fibers applied – Plural direction application of coating materials or...
Patent
1985-12-16
1987-09-08
Larson, Lowell A.
Coating processes
Solid particles or fibers applied
Plural direction application of coating materials or...
427286, 118663, 118410, 118697, 346140R, 222252, 417413, 417474, B05D 126, B05C 902, G01D 1516, F04B 4304
Patent
active
046923519
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method and apparatus for drawing a thick film circuit wherein a thick film circuit including resistors, capacitors and electric conductors is drawn on a substrate by discharging a paste from a discharge hole of a drawing nozzle.
BACKGROUND OF THE INVENTION
A thick film circuit is suitable for many types of electronic equipment, such as broadcasting radio receivers, television receivers, video tape recorders, communication equipment, and measuring equipment.
Such a thick film circuit is generally formed using the screen printing method. More specifically, a desired pattern is formed on a substrate made of almina ceramic using a conductor paste, resistor paste and so on, followed by drying and heating so as to manufacture a thick film circuit. However, the screen printing method uses a mask pattern, with the result that a longer time is required for the exchange of mask pattern and cleaning of mask pattern and squeegee, and thus it is unsuitable for small lot production and frequent changes of the circuit formed.
On the other hand, a method which involves drawing on a moving substrate using a paste directly extruded from a nozzle without employing the mask pattern is reported in the "1978 International Microelectronics Symposium of ISHM, Minneapolis, MN, Sept. 17, 1978" and is introduced in the journal "Electronic Packaging and Production (January, 1981), Pages 98-109".
In operation, a drawing nozzle having a discharge hole for discharging a paste is kept at a certain distance from a substrate and is moved relative thereto to apply the paste for drawing a predetermined pattern of a thick film circuit. This drawing method does not require a mask pattern because the thick film circuit is drawn by means of NC control, thereby allowing the operator to quickly change the pattern and instantly modify the circuit.
However, one of problems with such a drawing method is that, when it is used to draw a continuous thick film circuit pattern having linear lines and curves, difficulty is encountered in drawing curve portions of the pattern at a high speed due to inertia of the drive system of the nozzle. Therefore, to efficiently form the thick film circuit by the above-described drawing method, it will necessary to draw linear portions at a high speed and curved portions at a relatively low speed. However, this technique does not produce satisfactory results because of the occurrence of variations in the film thickness and line width caused by the difference of moving speed of the nozzle between linear portions and curve portions. This problem will likewise be experienced in a method in which the substrate is moved without moving the drawing nozzle. Therefore, according to the conventional techniques, it is difficult to form the thick film circuit at a high speed and with high accuracy.
DISCLOSURE OF THE INVENTION
A primary object of the present invention is therefore to provide drawing method and apparatus which are capable of preventing variations of film thickness and line width due to the variations of the drawing speed.
Another object of the present invention is to provide drawing method and apparatus which are capable of drawing a thick film circuit at a high speed and with high accuracy, irrespective of the complexity of the drawing pattern.
These objects of the present invention are achieved by controlling the discharge rate of paste in accordance with the relative moving speed between a drawing nozzle and a substrate.
The present invention relates to a drawing method for drawing a thick film circuit, in which a drawing nozzle having a discharge hole at the end thereof is held close to a substrate for drawing a thick film circuit and a thick film circuit is drawn on the substrate by discharging a paste from the discharge hole and moving the drawing nozzle relative to the substrate. The method according to the present invention includes a method in which the moving speed of the drawing nozzle relative to the substrate is detected and the discharging amount
REFERENCES:
patent: 2659310 (1953-11-01), Ryba
patent: 3088434 (1963-05-01), Sprague et al.
patent: 3381623 (1968-05-01), Elliott
patent: 3781907 (1973-12-01), Gerber
patent: 3909831 (1975-09-01), Marchio et al.
patent: 3961599 (1976-06-01), Jones, Jr.
patent: 4485387 (1984-11-01), Drumheller
patent: 4558995 (1985-12-01), Furukawa et al.
IBM Technical Disclosure Bulletin, vol. 15, No. 10, Mar. 1973, pp. 3029-3030, New York, U.S.; R. Delio: "Extrusion Printing".
Kudo Shin-ichi
Maeda Yukio
Saeki Keiji
Larson Lowell A.
Matsushita Electric - Industrial Co., Ltd.
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