Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2001-10-01
2004-03-16
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S720000, C029S740000, C029S832000, C029S840000
Reexamination Certificate
active
06705004
ABSTRACT:
CROSS REFERENCE TO RELATED DOCUMENT
The present application is a 371 of PCT/JP00/01983, which was filed on Mar. 29
th
2000, which claims the benefit of Japanese Patent Application No. 11-88500, filed Aug. 30
th
1999.
TECHNICAL FIELD
The present invention relates to a method and apparatus for mounting electronic components such as a microchip or a semiconductor element onto a substrate. More particularly, the invention relates to a component mounting method and apparatus which employs a suction nozzle for holding and mounting a component onto a given area on a substrate.
BACKGROUND ART
In a conventional electronic component mounting apparatus, the speed of the mounting operation has been increased by raising the operating speed of the various drive units in order to cope with a demand for high-speed component mounting due to an increase in the number of components to be mounted. For example, in a component mounting apparatus shown in diagrammatic plan view in
FIG. 6
, a component supply table
2
on which a plurality of component supply units
1
are arranged is moved in the direction of arrangement of the component supply units
1
, so as to locate a component supply port
3
of a desired component supply unit
1
in position at a first station ST
1
for picking up components (not shown). A component supply unit
1
, known as a parts cassette, includes a holding tape (not shown) having recesses for storing electronic components, the recesses being arranged at intervals in the length direction of the holding tape, and a cover tape (not shown) stuck onto the upper surface of the holding tape, the cover tape used for preventing the electronic components from falling out, thereby supplying the components to the component supply port
3
continuously.
The component mounting apparatus also includes a rotary-type mounting head
9
. The mounting head
9
includes a rotary drum
8
having a plurality of nozzle units (not shown) equipped with a suction nozzle
7
(ten are shown by way of example in the Figure) at their bottom ends, the nozzle units arranged at equal intervals on the periphery of the drum
8
.
The components are mounted onto a substrate
10
by the following procedure: the rotary drum
8
is intermittently rotated through an angle corresponding to the interval of the nozzle units, whereby the suction nozzles
7
of the nozzle units are successively positioned at first to tenth stations ST
1
to ST
10
. By vertical movement of the nozzle unit, the suction nozzle
7
positioned at the first station ST
1
picks up an electronic component from a component supply port
3
of a component supply unit
1
. When the component held by the suction nozzle
7
is transported with the rotation of the rotary drum
8
and the nozzle
7
is positioned at a third station ST
3
for component recognition, the amount of positional offset of the component with respect to the center of the suction nozzle
7
and the position of the component itself are measured using image data picked up by a recognition camera (not shown) of a component recognition device
11
. Then, when the component reaches a fifth station ST
5
for position correction, the component is rotated by the nozzle unit by the amount of the offset in order to correct the offset of the component calculated by the image processing described above.
When the component is positioned in and stopped at a sixth station ST
6
for component mounting, a substrate
10
is located by moving a substrate holding table
12
in X and Y directions so that a desired component mounting area of the substrate
10
is positioned directly below the component held by the suction nozzle
7
. Then, the nozzle unit moves vertically, whereby the component held by the suction nozzle
7
is mounted onto the desired mounting area on the substrate
10
. In the seventh to tenth stations ST
7
to ST
10
, preparation for next component mounting such as replacement of the suction nozzle
7
is performed.
As typified by cellular phones, recent reduction in weight and thickness of electronic devices necessitates miniaturization of the substrate
10
which is accommodated therein, as well as mounting of smaller components with high density on the substrate. However, reduction of separation of adjacent components is limited by the mechanical structure of the electronic component mounting apparatus. The mounting precision of the electronic component mounting apparatus is scarcely a factor in restricting the reduction of separation of the components, since they are mounted on the substrate
10
after their position has been corrected in the fifth station ST
5
in accordance with the correction values calculated from the image data picked up at the third station ST
3
.
FIG. 7
is a diagrammatical recognition screen
13
which is picked up by the recognition camera of the component recognition device
11
at the third station ST
3
. Using this recognition screen
13
, the amount of offset (&Dgr;x, &Dgr;y) of the positional coordinates (x
1
, y
1
) of the center
17
a
of the image
17
of the component held by the suction nozzle
7
with respect to the positional coordinates (x, y) of the center
14
a
of the image
14
of the suction nozzle
7
, and the inclination of the electronic component with respect to the suction nozzle
7
are calculated. A correction value is calculated based on the data, and the position of the component is corrected in accordance with the correction value before it is mounted on the substrate
10
. Due to the improvement in resolution of the component recognition device, there is no particular problem in reducing the mounting separation of the components.
However, regarding the mechanical structure of the electronic component mounting apparatus, there is a problem as shown in FIG.
8
. When the nozzle unit
19
holding a component
18
with a suction nozzle
7
, the component
18
being in a positionally offset condition and corrected to face a given component mounting area of the substrate
10
, is lowered, the suction nozzle
7
may come into contact with a component
18
that has already been mounted in an adjacent position as shown at portion A, thereby damaging this component
18
and impairing the quality of the substrate
10
.
In order to avoid the problem, a suction nozzle
7
may have an extremely minute shape that it does not contact a previously mounted component
18
. However, the smaller the aperture of the suction nozzle
7
becomes, the lower the suctional force on a component
18
is, causing an increase in the rate of failure in picking up a component
18
, as well as an increase in the number of components
18
that are discarded due to the failure, and consequent economic loss. What is worse, the strength of the suction nozzle
7
is lowered due to increasing thinness of its outer wall, resulting in an increased frequency of maintenance of the suction nozzle
7
and increased costs.
The invention has been devised in the light of the above problems, and it is an object of the invention to provide a method and apparatus for mounting electronic components realizing the mounting of components at high densities on substrates employing a conventional suction nozzle without lowering the quality of the substrate due to damage of the components.
DISCLOSURE OF THE INVENTION
To achieve the above object, a component mounting method according to the present invention includes the following steps: an electronic with a suction nozzle and transported to above a substrate; the amount of offset of the component with respect to the suction nozzle is calculated; the feasibility of mounting the component held by the suction nozzle onto the substrate without hindrance is determined based on the amount of offset; and a component in respect of which the result of the determination is positive is mounted on the substrate.
According to the component mounting method, high quality of the substrates is achieved since the component held by the suction nozzle is arranged to be mounted on the substrate only when the amount of offset of the component is o
Hanada Keiji
Nagai Yoshiyuki
Yabuki Koichi
Jordan and Hamburg LLP
Phan Tim
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