Electric heating – Metal heating – By arc
Reexamination Certificate
1999-02-12
2001-03-20
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
C219S085120, C228S006200, C228S012000
Reexamination Certificate
active
06204471
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to parts soldering apparatus and method for soldering surface mounting type electronic parts on a circuit board.
DESCRIPTION OF PRIOR ART
In recent years, along with the downsizing of electronic circuit and high-density mounting of parts, a surface mounting technology for soldering chip parts such as semiconductor devices onto the parts mounting surface of a circuit board has developed.
Conventionally, the chip parts soldering apparatus of this type for surface mounting has a stage for freely positioning a circuit board and a loading arm for loading a chip part on the circuit board on this stage through a solder tip.
With such a chip parts soldering apparatus, in order to solder the chip part on the parts mounting surface of the circuit board, the chip part is loaded on the parts mounting surface of the circuit board, which has been positioned on the stage in advance, through a solder tip. Then the stage or the loading arm is heated. Thus the solder tip between the chip part and the circuit board is heated to be melted.
Japanese Patent Application Laid-Open No. 6-268028 (published on Sep. 22, 1994) has disclosed a semiconductor device manufacturing method in which solder is heated to be melted by heating the stage. The method disclosed in the laid-open patent application will be described as a prior art.
FIG. 13
is a schematic view for illustrating a soldering process in a parts soldering apparatus for semiconductor devices as a prior art. Solder bumps
103
are formed on electrodes
102
of an electronic part
101
. The solder bump
103
on the electrodes
102
of the electronic part
101
is aligned with electrodes
105
on a circuit board
104
placed on a heater
106
through a low-heat-conductivity member
107
for abutting the solder bumps
103
on the electrodes
102
. Next, the heater
106
is heated, the solder bumps
103
are melted and the electrodes
102
are thermally compressed onto the circuit board
104
.
As described above, in the conventional parts soldering apparatus, the stage or the loading arm is heated, and thereby the chip part is soldered.
However, the prior art has such problems that much time is required before the solder tip is melted. Thus the soldering speed is low and the productivity is low despite much electric power being consumed because soldering is performed by heating the stage or loading arm having a high heat capacity.
Also, the prior art has problems that the chip part floats by the surface tension of the melted solder when the solder tip is melted, moves in the horizontal direction, and shifts from the target mounting position. Therefore, the mounting accuracy of chip part on the circuit board is decreased, because the loading arm has only the function for merely loading the chip part on the circuit board.
Further, when a large number of chip parts are mounted on the circuit board by the solder reflow process etc., all of the chip parts are heated once in soldering. Therefore, it is necessary to remove in advance an oxide film on the solder tips before loading the parts by the scrubbing operation of the chip parts. Therefore, there arises such a problem that the mounting accuracy is further decreased.
An object of the present invention is to provide parts soldering apparatus and method which improve the productivity during parts soldering and increase the mounting accuracy of parts on a circuit board.
SUMMARY OF THE INVENTION
To realize the above object, a first feature of the parts soldering apparatus of the present invention having: a stage for positioning a circuit board whereon, the circuit board is mounted a solder tip whereon; a loading arm made of a light-transmitting material, for loading a part onto the solder tip; a fluctuating mechanism for pressing the loading arm toward the circuit board; and an optical source for irradiating light onto the part through the loading arm and for melting the solder tip by the conductive heat of the light irradiated onto the part.
A second feature of the parts soldering apparatus of the present invention further having: a fluctuating sensor for outputting a height detecting signal according to the height of the loading arm; and a controller for controlling the output power of the optical source in response to the height detecting signal from the fluctuating sensor.
A third feature of the parts soldering apparatus of the present invention is: the controller: turns on the optical source at a first output power during the time when the loading arm moves from the height at the time of loading of the part onto the solder tip to the height at the time of melting of the solder tip; turns on the optical source at a second output power lower than the first output power during the time when the loading arm moves from the height at the time of melting of the solder tip to the height at the time of solidified of the solder tip; and turns off the optical source after the loading arm has moved to the height of solidified of the solder tip.
A first feature of the parts soldering method of the present invention having the steps of: positioning a circuit board on a stage, the circuit board is mounted a solder tip whereon; loading a part onto the solder tip by a loading arm made of a light-transmitting material; and irradiating light onto the part through the loading arm with pressing the part toward the circuit board by the loading arm and melting the solder tip by the conductive heat of the light irradiated onto the part.
A second feature of the parts soldering method of the present invention is: the optical source is turned on at a first output power during the time when the loading arm moves from the height at the time of loading of the part onto the solder tip to the height at the time of melting of the solder tip; the optical source is turned on at a second output power lower than the first output power during the time when the loading arm moves from the height at the time of melting of the solder tip to the height at the time of solidified the solder tip; and the optical source is turned off after the loading arm has moved to the height of solidified the solder tip.
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patent: 4278867 (1981-07-01), Tan
patent: 4858308 (1989-08-01), Komori
patent: 5018936 (1991-05-01), Izumi et al.
patent: 5023426 (1991-06-01), Prokosch et al.
patent: 5250781 (1993-10-01), Kanda et al.
patent: 5591295 (1997-01-01), Onitsuka
patent: 5956607 (1999-09-01), Evers
patent: 0 430 861 A1 (1990-11-01), None
patent: 62-67894 (1987-03-01), None
patent: 62-134173 (1987-06-01), None
patent: 64-1233 (1989-01-01), None
patent: 2-232999 (1990-09-01), None
patent: 4-247700 (1992-09-01), None
patent: 6-268028 (1994-09-01), None
European Search dated Aug. 11, 2000.
Japanese Office Action dated Feb. 8, 2000 with partial translation.
Heinrich Samuel M.
McGinn & Gibb PLLC
NEC Corporation
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