Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
2001-10-09
2004-10-26
Chang, Richard (Department: 3729)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S739000, C029S720000, C029S832000, C029S834000
Reexamination Certificate
active
06807725
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and a system for mounting electric components on a circuit substrate, and particularly to the improvements of the art of inspecting the state in which each electric component is mounted on the circuit substrate.
2. Related Art Statement
It has been practiced to inspect, when a plurality of electric components (“ECs”) are mounted on a circuit substrate for producing an electric circuit, the state in which the ECs are mounted on the circuit substrate, for example, judge whether the ECs have been safely mounted on the circuit substrate, or whether the ECs have been mounted at appropriate positions or with appropriate attitudes on the circuit substrate.
ECs of a type which have no lead wires are temporarily attached to a circuit substrate with an adhesive or a solder paste, and then are finally fixed to the circuit substrate by hardening the adhesive or melting the solder paste. An EC mounting device mounts each EC on the adhesive or the solder paste applied in advance to each EC-mount portion of the circuit substrate. After all ECs are mounted on the circuit substrate, those ECs are finally fixed to the circuit substrate. An inspection is performed after the ECs are temporarily attached to the circuit substrate and/or after the ECs are finally fixed to the circuit substrate.
ECs of a type which have lead wires are temporarily attached to a circuit substrate by first inserting the lead wires through the holes formed in the circuit substrate and subsequently folding the lead wires onto the back surface of the circuit substrate, and then are finally fixed to the circuit substrate by soldering.
In either case, if an inspection is performed in the state in which the ECs are temporarily attached to the circuit substrate, the ECs can be finally fixed to the circuit substrate after an operator has solved the problems found by the inspection. Thus, the percentage of defective electric circuits can be reduced. Alternatively, the circuit substrate with which the problems are found can be discarded. In the latter case, the final fixing of the ECs to the circuit substrate can be omitted. Moreover, in the case where the problem that an EC is mounted with positional errors on a printed circuit board (“PCB”) in a temporary-attaching step can be distinguished from the problem that an EC is mounted with positional errors on a PCB in a final-fixing step, appropriate countermeasures can be taken to deal with those problems, respectively.
In the above-indicated background, U.S. patent application Ser. No. 09/015,521 assigned to the Assignee of the present application discloses a system which inspects, each time one EC is mounted on a circuit substrate, the state in which the one EC is mounted on the circuit substrate. More specifically described, immediately after each EC is mounted on the circuit substrate, the disclosed system takes the image of each EC and its vicinity, compares the taken image with a reference image pre-stored in a memory of the system, and judges whether each EC has been accurately mounted on the circuit substrate. Thus, the disclosed system does not need an inspecting device which is needed in the case where an inspection is performed after all ECs are temporarily attached to a circuit substrate, and which is provided at a position between an EC mounting device which temporarily attaches the ECs to the circuit substrate, and a final-fixing device such as an adhesive hardening furnace. Thus, the disclosed system can inspect the state in which each EC is mounted on the substrate, without increasing the total length of an electric-circuit assembly line or the production cost thereof.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an electric-component mounting method and an electric-component mounting system which can inspect the state in which each electric component is mounted on a circuit substrate, with a higher reliability than that of the above-indicated prior system, or can employ a memory having a smaller capacity than that of the above-indicated prior system because of no need to store image data representing the reference image in the memory.
The present invention provides an electric-component mounting method and an electric-component mounting system which have one or more of the technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (12). Any technical feature which includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to that technical feature. Thus, two or more of the following technical features may be combined, if appropriate. Each technical feature may be accompanied by a supplemental explanation, as needed. However, the following technical features and the appropriate combinations thereof are just examples to which the present invention is by no means limited.
(1) According to a first feature of the present invention, there is provided a method of mounting a plurality of electric components on a circuit substrate and thereby producing an electric circuit, comprising the steps of taking, immediately before each of the electric components is mounted on the circuit substrate, a first image of a first portion of the circuit substrate on which the each electric component is to be mounted and a second portion of the circuit substrate that is adjacent to the first portion, mounting the each electric component on the circuit substrate, taking, immediately after the each electric component is mounted on the circuit substrate, a second image of the mounted electric component and the second portion adjacent to the mounted electric component, and inspecting, by comparing the first and second images with each other, a state in which the each electric component is mounted on the circuit substrate. The timing of “immediately before each of the electric components is mounted on the circuit substrate” means a timing after the preceding electric component (“EC”) has been mounted on the circuit substrate and before the each EC is mounted on the circuit substrate, or means, in the case where the circuit substrate is moved so as to be positioned relative to an EC mounting head (more strictly, an EC mounting position), a timing after the substrate has been positioned relative to the EC mounting head, for mounting of the each EC, and before the each EC is mounted on the circuit substrate. The timing of “immediately after the each electric component is mounted on the circuit substrate” means a timing after the each EC has been mounted on the circuit substrate and before the following EC is mounted on the circuit substrate, or means, in the case where the circuit substrate is moved so as to be positioned relative to the EC mounting head, a timing after the each EC has been mounted on the circuit substrate and before the substrate is moved so as to be positioned relative to the EC mounting head, for mounting the following EC. However, those timings do not mean a very short time before or after the mounting of each EC. In the case where an EC is mounted on a circuit substrate, a first image taken before the mounting of the EC and a second image taken after the mounting of the EC differ from each other. That is, the mounting of each EC influences the taken images. Comparing the two images with each other can lead to judging whether each EC has been safely mounted on the circuit substrate, or whether each EC has been accurately mounted on the first portion (i.e., EC-mount portion) of the circuit substrate. It is also possible to calculate positive and/or negative amounts of x-direction and y-direction positional errors of each EC mounted on the circuit substrate, and/or a positive or negative angular amount of rotation-position error of the mounted EC about an axis line passing through the center of the EC. One or more of those judging and calculating operations is or are one or more examples of the EC-mounting inspecting operati
Asai Koichi
Suhara Shinsuke
Chang Richard
Fuji Machine Mfg. Co. Ltd.
Oliff & Berridg,e PLC
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