JP3535988B2 - Reflow furnace and temperature control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow furnace for soldering and a temperature control method therefor.

[0002]

2. Description of the Related Art FIG. 3 is a schematic vertical sectional view of a conventional reflow furnace, and FIG. 4 is a transverse sectional view thereof.

In this reflow furnace, a conveyor 2 is arranged so as to penetrate through a horizontally oriented tunnel-shaped furnace wall 1 and inside the furnace wall 1 along the moving direction of the chain conveyor 2, 3, fourth heating zones 3a, 3b, 3c,
3d is provided adjacently. Heating zone 3 at both ends
a and 3d include upper and lower panel heaters 5a, 5b and 6 for heating a soldering target 4 such as an electronic component on the conveyor 2.
a and 6b are arranged.

Further, hot air circulating fans 7a, 7b, 7c, 7d are arranged above the first, second, third, and fourth heating zones 3a, 3b, 3c, 3d, respectively, and the hot air circulating fans 7a, 7b, 7c, 7d are arranged in each zone. It circulates hot air. Hot air circulation fan 7
Rotating shafts 8 of a, 7b, 7c and 7d penetrate the upper surface of the furnace wall 1 and are rotatably supported by bearings 9 provided on the upper surface of the furnace wall 1. A sprocket 10 is attached to the tip of the rotary shaft 8 passing through the bearing 9, and the sprocket 10 is rotated via a chain 14 from a sprocket 13 at the tip of an output shaft 12 of a motor 11 arranged outside the furnace wall 1. Power is given to the hot air circulation fans 7a, 7b,
7c and 7d are rotated. Both sides and the upper surface of the furnace wall 1 are covered and covered with a heat insulating material 15 such as rock wool. Such components are covered with the exterior plate 16.

In the reflow furnace having such a structure,
The upper and lower panel heaters 5a, 5b and 6a, 6b are energized, the energization current is controlled, and the hot air circulation fans 7a to 7d are controlled.
1 to 4 heating zones 3a to 3
d independently controlling the temperature, and the first to fourth heating zones 3a
The electronic parts and the like are soldered with cream solder while the soldering target 4 is transferred by the conveyer 2 across 3d to 3d in sequence. In this case, if the soldering target 4 is transferred from the left to the right in FIG.
The temperature distribution in the heating zones 3a to 3d is as shown in FIG. 5 (A) or FIG. 5 (B).

In particular, in FIG. 5 (A), in the first heating zone 3a and the fourth heating zone 3d, since the temperature of the soldering object 4 is rapidly raised, these first and fourth heating zones 3a are formed. , 3d are set higher than the temperatures of the second and third heating zones 3b, 3c.

However, the second and third heating zones 3
Since b and 3c are sandwiched between the first and fourth heating zones 3a and 3d, the adjacent first and fourth heating zones 3a and 3d
There is a problem that the heat from d flows into the second and third heating zones 3b and 3c, and the temperature of these second and third heating zones 3b and 3c cannot be controlled.

In order to solve such a problem, at present, as shown in FIG. 6, the heat insulating material 1 for the both side surfaces and the upper surface of the furnace wall 1 is used.
5 is removed to improve heat dissipation from the furnace wall 1 and
The temperature control of the heating zones 3b and 3c is possible.

[0009]

However, the reflow furnace in which the heat radiation from the furnace wall 1 is improved as shown in FIG. 6 has a problem that the heat radiation amount is large and the power consumption amount is increased.

An object of the present invention is to provide a reflow furnace which can switch heat radiation from the furnace wall and heat insulation of the furnace wall, and a temperature control method therefor.

[0011]

According to the present invention, three or more heating zones are provided adjacent to each other in the moving direction of the conveyor in the furnace wall, and at least the heating zones at both ends are soldered on the conveyor. (EN) A reflow furnace in which a heater for heating an object is arranged and a temperature control method therefor are improved.

In the reflow furnace according to the present invention, at least one heating zone of the three or more heating zones is provided with a ventilation passage on the furnace wall outside at least the upper side surface and the upper surface of the furnace wall. Insulated walls are provided to cool the ventilation passages
A feature is that a fan that blows air is provided .

According to the reflow furnace having such a structure, the cooling air is made to flow by the fan in the ventilation passage between the furnace wall and the heat insulating wall outside the furnace wall, thereby positively radiating heat from the furnace wall. Can be done. Further, by stopping the operation of the fan and stopping the cooling air flowing in the ventilation passage, it is possible to suppress the heat radiation from the furnace wall by the heat insulating wall and the air layer in the ventilation passage. Therefore, even in the heating zone sandwiched by the heating zones on both sides where the heater is present, the required temperature can be easily controlled by radiating heat from the furnace wall.

In the temperature control method of the reflow furnace according to the present invention, ventilation is provided to the furnace wall of at least one heating zone among the three or more heating zones, outside at least the upper side surface and the upper surface of the furnace wall. A heat insulating wall is provided via the passage, and when the temperature of the heating zone becomes higher than the set temperature,
It is characterized in that cooling air is made to flow through the ventilation passage by a fan to perform cooling.

According to the temperature control method of the reflow furnace having such a structure, when the temperature of the heating zone becomes higher than the set temperature, the cooling air is blown by the fan into the ventilation passage between the furnace wall and the heat insulating wall outside thereof. It is possible to positively dissipate heat from the furnace wall. Also, stop the fan operation.
By stopping and stopping the cooling air flowing in the ventilation passage, heat dissipation from the furnace wall can be suppressed by the heat insulating wall and the air layer in the ventilation passage. Therefore, even in the heating zone sandwiched by the heating zones on both sides where the heater is present, the required temperature can be easily controlled by radiating heat from the furnace wall.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first example of an embodiment of a reflow furnace according to the present invention. The parts corresponding to those in FIGS. 3 and 4 described above are designated by the same reference numerals.

In the reflow furnace of this example, first to fourth
A heat insulating wall 18 is provided on the upper side surface and the upper surface of the outer surface of the furnace wall 1 in the heating zones 3a to 3d through a ventilation passage 17. Fans 19 forcibly sending cooling air to the ventilation passages 17 are disposed below the ventilation passages 17, respectively. The fan 19 is provided in each of the first to fourth heating zones 3a to 3d. The heat insulating wall 18 is provided with an exhaust port 20 on the bearing 9 side. Other configurations are similar to those shown in FIGS. 3 and 4 described above.

Next, an example of such a reflow furnace temperature control method will be described. In this reflow furnace, the temperatures of the first to fourth heating zones 3a to 3d are detected by a temperature sensor (not shown), and the temperatures of the second and third heating zones 3b and 3c become higher than the set temperature, for example. At this time, under control of a controller (not shown), the fan 19 in the heating zone is operated to forcibly send the cooling air into the ventilation passage 17 for cooling. When the temperature of the heating zone decreases, the operation of the fan 19 is stopped to stop the cooling air flowing in the ventilation passage. Thereby, the heat insulating wall 18 and the ventilation passage 17
With this air layer, heat radiation from the furnace wall 1 can be suppressed.

Therefore, even in the heating zone sandwiched by the heating zones on both sides where the heater is present, the required temperature can be easily controlled by radiating heat from the furnace wall.

When comparing the power consumptions of the conventional reflow furnace and the reflow furnace of this example, the power consumption of the conventional reflow furnace was 10 kwh, whereas the power consumption of the reflow furnace of this example was 7 kwh. Yes, we were able to reduce power consumption by about 30%.

FIG. 2 shows a second example of the embodiment of the reflow furnace according to the present invention. The parts corresponding to those in FIG. 1 described above are denoted by the same reference numerals.

In the reflow furnace of this embodiment, instead of the fan 19 used in FIG. 1, a shutter 21 is provided at the entrance of each ventilation passage 17 so as to be openable and closable.

When performing temperature control in such a reflow furnace, the temperature of the first to fourth heating zones 3a to 3d is detected by a temperature sensor (not shown), and for example, the second and third heating zones are used. When the temperature of 3b, 3c becomes higher than the set temperature, the shutter 21 of the heating zone is opened by the control of the controller (not shown), and the cooling air is sent to the ventilation passage 17 for cooling. When the temperature of the heating zone decreases, the operation of the shutter 21 is stopped to stop the cooling air flowing in the ventilation passage. Thereby, heat insulation from the furnace wall 1 can be suppressed by the heat insulating wall 18 and the air layer of the ventilation passage 17.

With such a structure, the same effect as in the first example can be obtained.

In this example, the heat insulating wall 18 is provided through the ventilation passages 17 on the upper side surface and the upper surface of the outer surface of the furnace wall 1 in the first to fourth heating zones 3a to 3d. This heat insulating wall 18 is provided with the second and third heating zones 3b,
3c, only the second heating zone 3b, only the third heating zone 3c, or the like.

Further, although the reflow furnace having four heating zones has been described in the present embodiment, the present invention is not limited to this and can be similarly applied to a reflow furnace having three or more heating zones. Is.

[0027]

In the reflow furnace according to the present invention, at least one heating zone of the three or more heating zones is provided with ventilation passages outside at least the upper side surface and the upper surface of the furnace wall. A heat insulating wall is provided to cool the ventilation passage.
Since a fan that blows off air is provided, cooling air can be made to flow through this ventilation passage by the fan , so that heat radiation from the furnace wall can be positively performed. Also, the work of the fan
By stopping the operation and stopping the cooling air flowing in the ventilation passage, the heat radiation from the furnace wall can be suppressed by the heat insulating wall and the air layer in the ventilation passage. Therefore, even in the heating zone sandwiched by the heating zones on both sides where the heater is present, the required temperature can be easily controlled by radiating heat from the furnace wall.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first example of an embodiment of a reflow furnace according to the present invention.

FIG. 2 is a cross-sectional view showing a second example of the embodiment of the reflow furnace according to the present invention.

FIG. 3 is a vertical sectional view of a conventional reflow furnace.

FIG. 4 is a cross-sectional view of a conventional reflow furnace.

5 (A) and (B) are 2 of each heating zone of the reflow furnace.
It is a temperature distribution figure of a seed.

FIG. 6 is a cross-sectional view of a conventional reflow furnace having another structure.

[Explanation of symbols]

1 furnace wall 2 conveyors 3a to 3d First to fourth heating zones 4 Soldering target 5a, 5b, 6a, 6b Panel heater 7a-7d Hot air circulation fan 8 rotation axes 9 bearings 10 sprockets 11 motor 12 Output shaft 13 sprockets 14 chains 15 Insulation 16 Exterior plate 17 Ventilation passage 18 Insulation wall 19 fans 20 exhaust port 21 shutter

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Claims (2)

(57) [Claims] 1. A furnace wall is provided with three or more heating zones adjacent to each other along a moving direction of a conveyor, and at least the heating zones at both ends are heaters for heating a soldering object on the conveyor. In a reflow furnace in which at least one heating zone of the three or more heating zones is provided in the furnace wall through a ventilation passage with respect to at least an upper side surface and an upper surface of an outer surface of the furnace wall. A reflow furnace comprising a heat insulating wall and a fan for flowing cooling air in the ventilation passage . 2. A heater for heating a soldering object on the conveyor in at least three heating zones adjacent to each other in a furnace wall along a moving direction of the conveyor. In the temperature control method for a reflow furnace, the ventilation is provided to the furnace wall of at least one heating zone of the three or more heating zones to at least an upper side surface and an upper surface of an outer surface of the furnace wall. A heat insulating wall is provided through a passage, and when the temperature of the heating zone becomes higher than a set temperature, cooling air is blown through the ventilation passage by a fan to cool the reflow furnace. Method.