JPH04167966A - Reflow soldering device - Google Patents

Abstract

PURPOSE:To prevent cooling during returning and to uniformize temperature distribution of electronic parts and a substrate by also arranging the return side of a conveyor for carrying the substrate at the high position so as to travel the upper side of a heater. CONSTITUTION:A return chain 15b crosses horizontally the upper part of second heater 12 and moves in the opposite direction to the traveling direction of a carrier chain 15a in the arrow C direction. The return chain 15b travels toward a reflow solder vessel with a lower set temperature from a reflow solder vessel with a high set temperature and returns while being heated by each heater and is again used as the carrier chain 15a. Consequently, it is prevented that the set temperature at each preliminary solder vessel is decreased and the temperature nonuniformity is caused and temperature control in each vessel is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a reflow soldering device, and in particular, a conveyor that conveys a board on which electronic components are mounted passes over a heater to return to its initial position. In this way, the conveyor is not cooled during its return stroke, but instead returns to its initial position while being warmed by the heater, suppressing heat dissipation from the return side conveyor and reflow soldering bath. It relates to a reflow soldering device that allows for easy temperature control.

Conventional technology In conventional reflow soldering equipment, a board on which electronic components are mounted and cream solder is applied is gradually preheated in a preheating tank, and then soldered in a reflow soldering tank set to the solder melting temperature. The structure is such that soldering is performed by melting, and in the next step, the board is forcibly cooled to complete the soldering. At this time, the board is automatically conveyed by a conveyor such as a chain or net, and after soldering is completed, the conveyor passes through a low-temperature area far below the heater and wraps it around to return to the initial position. Thermal energy supplied during heating is dissipated into the outside air from the conveyor on the return side, resulting in energy loss, and reflow soldering has the drawback of increasing the running cost of the equipment.

In addition, if a conveyor, which has a large heat capacity compared to electronic components, is exposed to low-temperature outside air and cools down to near room temperature, a board on which electronic components are mounted may be placed on the conveyor and returned to the reflow soldering bath. When conveying the substrate inside the chamber, the heat energy from the heater is absorbed by the conveyor, which tends to cause uneven temperature rise of the substrate.In order to prevent this and maintain a uniform temperature distribution inside the chamber, the conveyor If the speed is slowed down, there is a drawback that the production efficiency is lowered, and in any case, there is a drawback that it is difficult to control the temperature inside the preheating tank and the reflow soldering tank.

Purpose The present invention was made in order to eliminate the drawbacks of the above-mentioned prior art, and its purpose is to perform reflow soldering in an apparatus having a structure in which a conveyor for conveying substrates runs above a heater. By arranging the return side of the substrate conveyor at a high position so as to run above the heater, the conveyor is heated by the heater even during its return, thereby preventing cooling during its return. In addition, this allows the board to be placed on a heated container and transported, ensuring uniform temperature distribution of electronic components and boards, and reducing the temperature in the preheating tank and reflow soldering tank. The goal is to make management easier. Another purpose of reflow soldering is to reduce energy loss, thereby reducing the running cost of the apparatus, and to increase the conveyance speed of the conveyor, thereby improving production efficiency.

Configuration In short, the present invention provides a reflow soldering apparatus having a structure in which a conveyor for conveying substrates runs above a heater, and is arranged at a high position so that the return side of the conveyor for conveying substrates also runs above the heater. It is characterized by:

The present invention will be explained below based on embodiments shown in the drawings. As shown in FIG. 1, the reflow soldering apparatus 10 according to the present invention includes a first preheating tank 1, a second preheating tank 2,
It includes a third preheating tank 3, a reflow soldering tank 4, and a substrate conveyor 6.

The interior of the first preheating tank 1 is configured to reach an initial preheating temperature using the first heater 11 as a heat source, and is thermally isolated from the outside.

The second preheating tank 2 is arranged adjacent to the first preheating tank 1, and the second preheating tank 2 is used for second stage preheating using the second heater 12 as a heat source. The device is configured to reach a certain temperature, and has a structure in which the device is thermally isolated from the outside.

The third preheating tank 3 is disposed adjacent to the second preheating tank 2, and the interior of the third preheating tank 3 is used as a final stage of preliminary heating using the third heater 13 as a heat source. The device is configured to reach a heating temperature, and has a structure in which the device is thermally isolated from the outside.

The reflow solder tank 4 is arranged adjacent to the third reflow solder tank 3, and the inside of the reflow solder tank 4 uses a more powerful fourth heater 14 as a heat source to reach the melting temperature of the cream solder. The device is configured to be thermally isolated from the outside.

The forced cooling device 5 circulates air sucked in by a blower (not shown) at high speed through a nozzle (not shown) to air-cool the board 8 after soldering is completed to solidify the solder. It has become.

The conveyor 6 has a pair of chains 15 wrapped around a driven sprocket 7) 23.24°25.26 and an idle sprocket 28 fixed to a rotatably supported shaft 16°18, and fixed to a rotating shaft 20. The drive sprocket 21 includes a motor 19 that transmits driving force to a driven sprocket 23 via a driven sprocket 21 and a belt 22.

Also, the distance between the driven sprockets 23, 24, 25, 26 and the idle sprocket 28 fixed to the shaft 16.18 is adjusted in accordance with the width of the board 80, and the distance between the pair of chains 15 wound around each other facing each other is adjusted. is said to be adjustable.

Further, the conveyor chain 15a installed between the driven sprockets 23 and 24 enters the first preheating tank 1 through the opening 1a, and then enters the second preheating tank 2 through the opening 2a.
Then, from the opening 3a to the third preheating tank 3, the opening 4a
The conveyor chain 15a enters the reflow soldering bath 4 and further crosses the inside of the forced cooling device 5, and the conveyor chain 15a further passes through the first heater 11, the second heater 12, the third heater 13, and the fourth heater 14. The upper part is installed horizontally.

Further, the return chain 15b, which is an example of the return side of the conveyor 6 installed between the driven sprockets 25 and 26, passes through the forced cooling device 5, enters the reflow soldering bath 4 through the opening 4a, and then enters the reflow soldering bath 4 through the opening 4a. 3a to the third preheating tank 3, opening 2a to the second preheating tank 2, opening 1
a, passes through the first preheating tank 1, and transfers to the conveyor chain 15.
The first heater 11.a is located at a lower position than the first heater 11.a. Second heater 12. Third heater 13. Fourth heater 14
is placed above.

In addition, a net conveyor 32 wrapped around a driving sprocket 30 and an idle sprocket 31 fixed to a rotating shaft 29 is connected to the upper part of the first heater 11 , the second heater 12 , the third heater 13 , and the fourth heater 14 . and the return chain 15b.

Function The present invention is constructed as described above, and its function will be explained below. As shown in FIG. 1, as the motor 19 rotates, the conveyor chain 15a starts moving in the direction of arrow A. Referring also to FIG. The board 8 on which 9 is mounted is
It is transported into the first preheating tank 1 set at the preheating temperature. Further, the substrate 8 loaded on the conveyor chain 15a is transferred to a second preheating tank 2 and a third preheating tank 2 each having a higher set temperature.
The cream solder transferred to the preheating tank 3 and the reflow soldering tank 4 in that order and applied to various electronic components 9 is melted in the reflow soldering tank, and reflow soldering is performed.

In the forced cooling device 5 for the next process, the board 8 is transported, the molten solder is solidified, and the soldering is completed. ).

As shown in FIG. 2, the return chain 15b moves horizontally across the upper part of the second heater 12 in the direction of arrow C, opposite to the moving direction of the conveyance chain 15a. The return chain 15b travels from a reflow soldering tank with a higher set temperature to a reflow solder tank with a lower set temperature, but returns while being heated by each heater and is used again as the conveyance chain 15a, so each preliminary solder Temperature management in each tank is greatly facilitated without lowering the set temperature in the tank or causing temperature unevenness.

Further, when the substrate 8 loaded on the conveyor chain 15a falls off the conveyor chain for some reason and falls, the substrate 8 captured by the net conveyor 32 moving in the direction of the arrow will be moved in the direction of the arrow E. It is taken out in the direction and collected into the collection box 33.

Effects The present invention provides a reflow soldering apparatus having a structure in which a substrate conveyor runs above the heater as described above.
Since the return side of the substrate transport conveyor is also arranged at a high position so as to run above the heater, the conveyor is heated by the heater even during its return, which has the effect of preventing cooling during its return. In addition, this results in the ability to place the board on a heated conveyor and transport it, making it possible to equalize the temperature distribution of electronic components and the board, and making it easier to control the temperature in the preheating tank and reflow soldering tank. This has the effect of increasing the number of people.

In addition, since energy loss can be reduced, reflow soldering can reduce the running costs of the equipment, and it also has the effect of increasing production efficiency by increasing the conveyance speed of the container. There is.

[Brief explanation of drawings]

The drawings relate to embodiments of the present invention; Fig. 1 is a front view showing the entire apparatus for reflow soldering, and Fig. 2 is a partially enlarged front view showing the installed state and running direction of the conveyor and the 7-soto conveyor relative to the heater. . 1 is a first preheating tank, 2 is a second preheating tank, 3 is a third preheating tank, 4 is a reflow soldering tank, la, 2a, 3
a, 4a is an opening, 5 is a forced cooling device, 6 is a conveyor,
8 is a board, 9 is an electronic component, 10 is a reflow soldering device, 15 is a chain, 15a is a conveyance chain, and 15b is a return chain, which is an example of the return side of the conveyor.

Claims (1)

[Claims] A reflow soldering apparatus having a structure in which a conveyor for conveying substrates runs above a heater, characterized in that the return side of the conveyor for conveying substrates is also arranged at a high position so as to run above the heater. Soldering equipment.