JPH0241770A - Reflow device - Google Patents

Abstract

PURPOSE:To maintain the temp. of a wiring board and in a reflow device chamber always constant by administering the temp. of rails and chain conveyor by a temp. controller which controls the electric power to be supplied to heaters by a temp. sensor for measuring the temp. of the rails. CONSTITUTION:The temp. of the chain conveyor 15 is low in case of heating the wiring board 12 only by a 1st heaters 11a and 11b and, therefore, the temp. at both ends in contact with the chain conveyor 15 falls. The heater 16 and the rails 14 are in contact with each other and, therefore, if the temp. is increased by energizing the 2nd heater 16, the heat is transmitted to the rails 14 and the temp. of the rails 14 is eventually increased. The chain conveyor 15 supported by the rails 14, consequently, receives the heat conduction from the contact part thereof and the temp. thereof rises. The temp. of the rails 14 is measured by the temp. sensor 17 and is controlled by the temp. controller 18. The temp. of the chain conveyor 15 is thus easily maintained constant.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a soldering reflow apparatus used in the manufacturing process of circuit boards (hereinafter referred to as "boards") used in various electrical and electronic devices. It is something.

[Conventional technology]

BACKGROUND ART In recent years, as electric and electronic devices have become smaller, the substrates used in these devices have also become smaller and more dense. Such board beam flow soldering is often made by soldering desired components onto the surface of a wiring board.

70-Soldering is a wiring board for mounting components (
A board for mounting components is hereinafter referred to as a wiring board in order to distinguish it from a board meaning a finished product.] Apply reflow solder to the surface of the wiring board using screen printing or a dispenser, and place the components on the solder of the wiring board. After mounting on the plate, soldering is performed by heating with a device called a reflow device, melting the reflow solder, and then allowing it to solidify.

Methods of heating solder that are common in conventional glue flow devices include methods such as radiant heating using infrared rays, heating using hot air, and heating using latent heat of steam.

Regardless of the heating method used, in order to improve production efficiency, the wiring board is first placed on a transport device, such as a transport conveyor, and the parts are placed thereon and the parts to be joined are continuously heated. things are being done.

Recently, there has been an increase in the number of boards with components mounted on both sides of the wiring board, so chain conveyors that can support wiring boards on both sides are increasingly being used as transport conveyors.

An example of a flow device using such a conventional chain conveyor will be explained with reference to the drawings. FIG. 3 is a schematic cross-sectional view of the same. In the figure, 1 beam is a wiring board coated with flow solder and further mounted with parts (not shown), and this wiring board 1 is placed on a chain conveyor 2. It is transported from side A to side B in the figure. Reference numeral 3 denotes a panel heater that heats the components to be transported and the wiring board 1, thereby melting the solder. 4 lowers the temperature of the wiring board by blowing cold air onto the heated wiring board with a cooling fan;
It acts to solidify the solder.

A sectional view taken at W-TV'@ in FIG. 3 is shown in FIG. 4.

As shown in FIG. 4, in the conventional adhesive flow apparatus 2, a wiring board 1 has components 4 placed at predetermined positions, and is placed on two conveyor chain conveyors. Further, the chain conveyor 2 is supported by rails 5 and is configured to move and convey the wiring board 1. Further, reference numeral 3 indicates fL taper panel heaters provided on the upper and lower sides, and the wiring board 1 is heated by these heaters, and soldering with the component 4 is performed.

In such conventional glue flow equipment, the chain conveyor 2
As is clear from FIG. 3, since it is necessary to place and unload the wiring board 1, the wiring board 1 is removed from the chamber 6 of the reflow apparatus (see FIG. 3) where heating is performed. Therefore, the temperature of the chain conveyor 2 outside the heating chamber 6 is lower than the temperature inside the heating chamber 6 of the apparatus.

When the chain conveyor 2 is guided by the rail 5 into the heating chamber 6 again at this low temperature, it is simply heated by the upper and lower heaters 3 to melt the solder. Within the same wiring board 1, the temperature of the portion where the conveyor chain conveyor 2 is placed and in contact with it is inevitably lower than the temperature of the central portion.

An example of this temperature distribution is shown in FIG. 5 by a broken line a. The temperature at positions D and D+ of the chain conveyor 2 supported by the rail 5 in FIG. 4 is lower than that at the center. This causes a difference in the ease with which the solder melts, resulting in an insufficient melting state, and as a result, there is a problem in that soldering tends to be defective.

Utility Model Application Publication No. 61-3636 as a means for improving the temperature non-uniformity of the conventional wiring board 1 caused by the above-mentioned chain conveyor 2.
No. 4 idea has been submitted. Figure 6 (
As shown in FIG. By shaking, the amount of heat radiation near the chain conveyor 2 is increased, and the temperature outside the chamber 6 is lowered.
The temperature of the chain conveyor 2 is raised, and the temperature of the wiring board 1 is also raised to eliminate the temperature difference with the central part, that is, to make the temperature uniform.

[Problem to be solved by the invention]

However, in the device of Utility Model Application Publication No. 61-36364, the temperature of the rail 5 also rises, and as a result, the temperature of the wiring board 1 on the chain conveyor 2 is higher than that of the central part. The temperature distribution on the wiring board 1 is already shown in FIG. To perform heating, the ambient temperature in chamber 6 of the reflow equipment is gradually raised.For this reason, when multiple wiring boards are transported, there is a difference in temperature between the wiring boards, which results in the soldering of the formed boards. There were times when variations occurred.

Therefore, it is an object of the present invention to prevent temperature rise and temperature variation in the atmosphere inside the room of a reflow apparatus, to prevent temperature differences between wiring boards, and to improve the overall temperature distribution even if there are two wiring boards on each wiring board. The key is to make it even.

[Means to solve the problem]

The parts and the wiring board are soldered by heating the wiring board coated with the beam flow solder of the present invention and the components placed on the wiring board, melting the reflow solder, and then cooling and solidifying the solder. , in a reflow apparatus having a chain conveyor for mounting and conveying the wiring board, a heater is installed inside and/or in contact with the rail on the outside of the rail supporting the chain conveyor for conveying the wiring board; Contact 7S: A flow device that includes a temperature sensor, a power source for supplying power to the heater, and a temperature adjustment device that controls the power supplied to the heater using the temperature sensor.

[Effect]

In the reflow apparatus according to the present invention, the heater provided in contact with the rail generates heat due to the power supplied from the power supply, thereby raising the temperature. Due to the rise in temperature of this heater, the temperature of the rail increases due to the heat transmitted from the heater, and due to this rise in temperature of the rail, the conveyor chain conveyor supported by one rail is also heated and its temperature rises, and the temperature of the conveyor chain increases. Heat is also transferred to the part of the wiring board that is placed in contact with the conveyor, which prevents the temperature of that part of the wiring board from decreasing due to the temperature drop of conventional chain conveyors.

Furthermore, in the glue flow apparatus of the present invention, a temperature sensor is provided in contact with the rail, and the temperature of the rail is measured, and the temperature control device that controls the electric power supplied to the heater from this temperature sensor is used to control the rail and chain conveyor. Since the temperature is controlled, the temperature inside the wiring board 8 and the reflow apparatus chamber can be kept constant and stable at all times.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view in the width direction of an embodiment of the glue flow device of the present invention. In Figure 1, l l a': J
6 and llb are first heaters similar to those in the conventional device for heating the wiring board 12 and components 13 and melting the solder. 14 is a rail, and this rail 14
supports a chain conveyor 15, on which the wiring board 12 is placed at the end of the chain conveyor 15.
is a second heater embedded in the rail 14.
It has the effect of heating the rail 14. 17 is a temperature sensor (thermocouple) for measuring the temperature of the rail; 18 is a temperature control device; and 19 is a power source controlled by the temperature control device 18.

2. The rail 14a1, heater 16a, and temperature sensor 7& on the left side in FIG.
It has the same configuration as the heater 16 and the temperature sensor 7, and is provided with a temperature control device and a power source (not shown).

In the glue flow apparatus of this embodiment, there are two first heaters 11a and 11a. When the wiring board 12 is heated only by
As mentioned above (when the temperature of the chain conveyor 15 is low, the temperature distribution of the wiring board 12 is such that the temperature at both ends in contact with the chain conveyor 15 decreases, as shown by the broken line a explained earlier in FIG. 5). .At this time, the second heater 1
6 is energized to raise the temperature, heat is transferred to the rail 14 because the heater 16 and the rail 14 are in contact with each other,
This will increase the temperature of the rail 14. As the temperature of the rail 14 rises, the chain conveyor 15 supported by the rail 14 also receives heat conduction from its contact portion, and its temperature also rises. As a result, there is no heat conduction from the wiring board 12 to the chain conveyor 15, and no heat is taken away.
The temperature of wiring board 12 does not decrease.

Next, the temperature of the rail 14 is measured by a temperature sensor (thermocouple) 17, and controlled by a temperature control device 18. Therefore, the temperature of the chain conveyor 15 can be easily kept constant, and unnecessary heat generation can be avoided. Since it is possible to suppress the temperature, it hardly affects the temperature of the air inside the reflow apparatus chamber.Furthermore, the temperature control by the second heater 16 is easy to control the solid temperature. The first heaters 11a and 111)
No coordinated control action is required.

As a result, the temperature of the wiring board becomes uniform as shown by solid line C in FIG.

Next, a second embodiment of heating the chain conveyor 15 and, by extension, the wiring board 12 will be described with reference to FIG. In Fig. 2 I'CJ, a second heater 26 is installed to heat the side surface of the conveyor rail 14 (here, the rail is heated), 27 is a thermocouple for temperature measurement, and 15 is a chain conveyor. (Temperature control device and power supply have been omitted).

In this case as well, the temperature of the wiring board is prevented from decreasing by the same effect as in the first embodiment, and the above-mentioned problem is solved. However, compared to the first embodiment, this embodiment has a simpler structure and is advantageous in terms of cost (although this is advantageous, half of the heater is exposed indoors, so it has a slight effect on the indoor temperature. .

〔Effect of the invention〕

According to the glue flow device of the present invention, it is possible to prevent the temperature of the atmosphere in the room from rising, and to reduce the temperature difference between different wiring boards.In addition, the temperature of the chain conveyor can be easily controlled. Therefore, the temperature of the wiring board placed on it can be uniformly controlled. Also, it can be carried out without cooperative control between the first heater and the second heater.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view in the width direction of one embodiment of the glue flow device of the present invention, Fig. 2 is a second embodiment of the present invention, and is an explanatory diagram of the vicinity of the rail, and Fig. 3 is a cross-sectional view of a normal glue flow device. 4 is a cross-sectional view taken along the line ■-IV' in FIG. 3, FIG. 5 is a diagram showing the humidity distribution of the wiring board, and FIG. 6 is a width direction of another conventional rift device. FIG. 11a, llb...First heater 12...Wiring board, ]3...Parts, 14...Rail, 15...Chain conveyor, 16...Second heater 17...
・Thermocouple, 18... Temperature control device, 19... Power supply,
26...Second heater 27...Thermocouple.

Claims (1)

[Claims] 1. The wiring board coated with reflow solder and the components placed on the wiring board are heated, the reflow solder is melted, and then cooled and solidified to solder the components and the wiring board, and A reflow apparatus having a chain conveyor for mounting and transporting wiring boards, a heater in contact with the rail inside and/or outside of the rail supporting the wiring board transporting chain conveyor, and a temperature sensor in contact with the rail; A reflow apparatus comprising: a power supply for supplying power to the heater; and a temperature adjustment device for controlling power supplied to the heater using the temperature sensor.