Metal fusion bonding – With control means responsive to sensed condition – Work-responsive
Reexamination Certificate
2001-12-11
2003-10-28
Dunn, Tom (Department: 1725)
Metal fusion bonding
With control means responsive to sensed condition
Work-responsive
C432S207000, C432S227000, C432S249000
Reexamination Certificate
active
06637637
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflow apparatus preferably usable for performing reflow soldering of an electronic component to a printed circuit board.
2. Description of the Related Art
A reflow soldering apparatus includes a pre-heating unit, a main heating unit, and a cooling unit, which are accommodated in a furnace housing. The reflow soldering apparatus solders an electronic component to a printed circuit board (hereinafter, referred to as a “board” or a “workpiece”) or the like as follows. The electronic component is placed on a printed circuit board with solder and is transported to the inside of the furnace housing. The solder is pre-heated by the pre-heating unit, and then heated by the main heating unit to a soldering temperature so as to be melted. Then, the solder is cooled by the cooling unit.
The heating units in the reflow apparatus use, for example, hot winds, heat rays such as infrared rays, or a combination thereof.
An exemplary conventional reflow apparatus
800
of a hot wind circulation type has a structure as shown in FIG.
8
. The reflow apparatus
800
operates as follows.
An air blower
54
includes a fan
52
provided below a bottom surface
7
a
of a board
7
carrying an electronic component to be soldered, and a motor
53
for rotating the fan
52
. The air blower
54
absorbs air from the outside to the inside of the reflow apparatus
800
. Then, the air circulates in the reflow apparatus
800
. More specifically, the air flows in a direction of arrows A, and is heated by a heater
51
so as to become a hot wind. Then, the hot wind flows in a direction of arrows B and is blown toward a top surface
7
b
of the board
7
. The hot wind collides into the top surface
7
b
, flows downward in a direction of arrows C, and is absorbed into an absorbing opening (not shown) of the fan
52
.
FIG. 9
shows another conventional reflow apparatus
900
disclosed in Japanese Laid-Open Publication No. 11-192545. The reflow apparatus
900
includes a pair of fans
52
for respectively heating both a bottom surface
7
a
and a top surface
7
b
of a board
7
. The reflow apparatus
900
also includes a heater
51
above the top surface
7
b
and another heater
51
below the bottom surface
7
a
. The pair of fans
52
are SIROCCO fans both rotatable about a rotation shaft
52
a
provided in a lower part of the inside of a furnace housing
90
and arranged parallel to the board
7
and the heaters
51
. The rotation shaft
52
a
is driven by a motor
53
via a belt conveyor mechanism
55
.
FIG. 10
shows still another conventional reflow apparatus
1000
also disclosed in Japanese Laid-Open Publication No. 11-192545. The reflow apparatus
1000
includes two air blowers
54
for respectively heating a bottom surface
7
a
and a top surface
7
b
of a board
7
. The reflow apparatus
1000
includes heaters
51
respectively provided above and below the board
7
, and the air blowers
54
each including a fan
52
and a motor
53
.
The above-described conventional reflow apparatuses have the following problems.
The reflow apparatus
800
shown in
FIG. 8
only heats the top surface
7
b
of the board
7
. Therefore, it takes a relatively long time to uniformize the temperature of the entire board
7
. Furthermore, a dispersion in the temperature of the board
7
may cause a defect in soldering.
The reflow apparatus
900
shown in
FIG. 9
drives the fans
52
by the motor
53
via the belt conveyor mechanism and the rotation shaft
52
a
which is longer than the width of the reflow apparatus
900
. Therefore, the reflow apparatus
900
has the problems of, for example, a bearing (not shown) for supporting the rotation shaft
52
a
having a short life and a belt of the belt conveyor mechanism needing regular replacement. These all contribute to making maintenance of the reflow apparatus
900
difficult.
The reflow apparatus
1000
shown in
FIG. 10
includes two air blowers
54
respectively above and below the board
7
, and therefore is unavoidably relatively large in size.
SUMMARY OF THE INVENTION
A reflow apparatus according to the present invention includes at least one heating unit. Each of the at least one heating unit includes an air blower for circulating air; a partition for defining an air circulating path; at least a first slit heater and a second slit heater for heating a workpiece with the circulating air, the workpiece having a first surface and a second surface; and a furnace housing for accommodating the workpiece. The air blower includes a first fan for blowing the air toward the first surface of the workpiece, a second fan for blowing the air toward the second surface of the workpiece, and a motor for rotating the first fan and the second fan. The first fan and the second fan are provided in correspondence with the at least first slit heater and the second slit heater.
In one embodiment of the invention, the motor has a rotation shaft provided above the workpiece in a perpendicular direction to workpiece.
In one embodiment of the invention, the first fan and the second fan have different sizes from each other.
In one embodiment of the invention, the first slit heater and the second slit heater are provided so as to interpose the workpiece therebetween. Each of the first slit heater and the second slit heater has a slit structure including a plurality of pipe heaters, each having a nickel-chrome wire coiled therein, and a plurality of flat metal plates arranged in connection with, and perpendicular to, the pipe heaters.
In one embodiment of the invention, the air circulating path defined by the partition includes a first air path for guiding the air from the first fan toward the first slit heater, a second air path for guiding the air from the second fan toward the second slit heater, and a third air path for guiding the air from the first slit heater to the first surface of the workpiece and further to the first fan and the second fan, and guiding the air from the second slit heater to the second surface of the workpiece further to the first fan and the second fan.
In one embodiment of the invention, the at least one heating unit includes a plurality of heating units, and each of a temperature of the plurality of heating units is independently adjustable.
Thus, the invention described herein makes possible the advantages of providing a compact reflow apparatus which can heat a workpiece uniformly for satisfactory soldering, has a relatively long life, and is easy to maintain.
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translation of JP-11192545.
Shimano Kiyoharu
Takakura Hiroshi
Yamasaki Hirofumi
Dunn Tom
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
Stoner Kiley
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