Metal working – Method of mechanical manufacture – Electrical device making
Patent
1986-04-28
1988-12-13
Goldberg, Howard N.
Metal working
Method of mechanical manufacture
Electrical device making
29709, 29714, H05K 1304
Patent
active
047900695
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for mounting electronic parts, particularly electronic parts formed into a chip-like shape (which will be hereinafter referred to as chip part), on a circuit substrate such as printed circuit board.
DESCRIPTION OF THE PRIOR ART
In conventional electronic part mountings, vacuum absorption is generally employed as shown in FIG. 1 wherein a chip part 1 is attracted through a nozzle 2. FIG. 1 (a) to FIG. 1(d) are illustrations of the conditions of vacuum absorption of the chip part 1. FIG. 1(a) through FIG. 1(d) respectively illustrate the condition that the chip part 1 has normally been absorbed by the nozzle 2, the condition that it has lengthwise been drawn thereby, the condition that it has obliquely been absorbed thereby, and the condition that it has not been attracted. Of these, FIG. 1(b) to FIG. 1(d) show error of the absorption of the chip part 1, and therefore detection should be made to determine these conditions.
FIG. 2 is an illustration of a conventional vacuum system for the detection of absorption error of a chip part. In the figure, the reference numerals 3 and 4 represent a filter, numeral 5 designating a throttle valve, numeral 6 depicting a magnet, numerals 7 and 8 being a proximity switch, and numeral representing a vacuum source. This system is based on a method in which the absorption error is detected on view of differential pressure. In response to the normal absorption of the chip part 1 to the nozzle 2, the pressure of the nozzle side of a differential measuring device 10 is further decreased. As a result, the magnet 6 is moved in the direction of an arrow to thereby turn on the proximity switch 8. On the other hand, in the case of the occurrence of absorption error thereof as shown in FIGS. 1(b) to 1(d), the magnet 6 causes no movement because air is introduced from an absorbing opening of the nozzle 2, resulting in turning on another proximity switch 7.
However, one of problems with such a method is that fine adjustment of the throttle valve 5 is required in conformity with the introduction amount varied in accordance with the absorbing condition of the chip part 1, taking a long time for system maintenance.
Various detection methods of the type other than the vacuum differential pressure type of FIG. 2 are known. However, any of them relate to a technique in which the detection is made on the basis of the degree of vacuum, i.e., on the basis of air leak caused by the absorption error of a chip part. Therefore, difficulty is encountered to set a detection reference and further there arises an disadvantage in system maintenance that the detection reference is varied due to the absorption of dust and the like.
DISCLOSURE OF THE INVENTION
A primary object of the invention is therefore to provide a method for mounting electronic parts which is capable of increasing reliability in terms of the detection of a chip part and simplifying system maintenance.
Another object of the invention is to provide an apparatus for realization of the method of the invention.
The above-mentioned object is accomplished by a technique wherein a distance between the under surface of a part maintaining device for maintaining an electronic part and a circuit substrate is measured when the electronic part is mounted on the circuit substrate and then a comparison is made between the measured distance and the thickness of the electronic part measured in advance. The determination that the electronic part has normally mounted thereon is made in accordance with the result of the comparison.
An electronic part mounting apparatus of the invention comprises a sliding shaft having a part maintaining device at an end thereof, a motor for moving the sliding shaft upwardly and downwardly, a drive unit for moving the sliding shaft within a horizontal plane, distance measuring means for measuring a distance between a circuit substrate and the under surface of the part maintaining device when an electronic part is mounted on the circuit su
REFERENCES:
patent: 3670388 (1972-06-01), Jack
patent: 4510683 (1985-04-01), Fedde et al.
Hasegawa Mikio
Itemadani Eiji
Maruyama Masahiro
Mori Kazuhiro
Goldberg Howard N.
Matsushita Electric - Industrial Co., Ltd.
Ross Taylor J.
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