JPH08298373A - Reflow system - Google Patents

Abstract

PURPOSE: To obtain a reflow system in which a heated substrate can be prevented from being softened to fall off a conveyor when the substrate is carried through a heating chamber while being supported, at the opposite side end parts thereof, by the conveyor and soldering is carried. CONSTITUTION: A conveyor 4 is set in a heating chamber 1 an a heater 8 and a fan 9 are disposed above the conveyor 4. A plurality of nozzles 11 for blowing the air toward substrates 6 being transferred on the conveyor 4 are disposed along the transferring direction of substrate 6. The substrate 6 blown with hot air softens thermally but is prevented from bending downward because it is blown with the air from below and thereby the substrate 6 does not fall off the conveyor 4. Fusion of solder is accelerated by winding a heating wire 14 around the nozzle 11 thereby heating the air. Furthermore, the substrate 6 is retained, at the opposite side end parts thereof, by means of a roller 16 so that the substrate 6 may not be blown by the air to fall off the conveyor 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow device for soldering electronic parts mounted on a board.

[0002]

2. Description of the Related Art A reflow apparatus heats a substrate by blowing hot air heated by a heater onto the substrate while transporting the substrate on which electronic components are mounted by a conveyor, thereby melting the solder and soldering the electronic components. It is designed to be attached.

[0003]

An endless chain is often used as a conveyer, and the substrate is heated with its melting point of solder (generally about 183 ° C.) or higher while being transported with its both end portions being supported by the endless chain. To be done. A glass epoxy substrate or the like is often used as the substrate, but the substrate softens when heated. Therefore, there is a problem that the substrate is easily bent in a downward convex shape and, in the worst case, falls from the endless chain.

Therefore, an object of the present invention is to provide a reflow apparatus which can prevent a substrate heated to a high temperature from being bent and falling from a conveyor.

[0005]

To this end, the present invention is directed to a heating chamber, a pair of left and right conveyors disposed inside the heating chamber, and a substrate which is conveyed with its both end portions supported by the conveyor. A reflow device including a heater for heating a substrate and a fan, in which a gas blowing unit for blowing gas from below is provided in the central portion of a substrate conveyed by a conveyor.

Preferably, the gas blowing means is provided with a heater for heating the gas.

Preferably, rollers are provided to press both end portions of the substrate onto the conveyor from above.

[0008]

According to the above construction, the gas is blown from below to the central portion of the substrate which is transported while being supported by the conveyor at both end portions thereof, thereby preventing the substrate from being bent downward.
This prevents the substrate from falling off the conveyor.
A heater is provided to control the temperature of the gas blown onto the lower surface of the substrate, and a roller is provided to prevent the substrate from being hit by the gas blown from below and falling from the conveyor.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing the internal structure of a reflow apparatus according to the first embodiment of the present invention, and FIG. 2 is a sectional view of a substrate conveyed by a conveyor of the reflow apparatus. In FIG. 1, reference numeral 1 is a heating chamber, and a conveyor 4 is horizontally arranged from its inlet 2 to its outlet 3. The conveyor 4 is an endless chain, is banded by a sprocket 5, and is driven by a motor (not shown) to rotate.

Reference numeral 6 denotes a board which is conveyed by the conveyor 4 and on which an electronic component 7 is mounted. A plurality of heaters 8 are provided above the conveyor 4. A fan 9 is provided above the heater 8. Reference numeral 10 is a motor for rotating the fan 9. By rotating the fan 9, the air heated by the heater 8 is blown onto the substrate 6 to heat the substrate 6. The substrate 6 is gradually conveyed from the inlet 2 toward the outlet 3 while gradually melting the solder (about 183 ° C.).
The above is heated to about 230 ° C. Further, the heater 8 does not exist below the fan 9 at the most downstream side (right end in the figure), and the fan 9 blows a relatively low temperature air onto the substrate 6 to cool and solidify the heat-melted solder.

Below the substrate 6 conveyed by the conveyor 4, a plurality of gas spraying means (4 in this embodiment) are provided.
No. of nozzles 11 are provided along the conveyance direction of the substrate 6. The nozzles 11 are arranged intensively from the vicinity of the highest substrate temperature, that is, the lowermost downstream (right end) heater 8 to a position where the substrate 6 is cooled by the fan 9 and hardened. A duct 12 communicates with the nozzle 11 and is connected to the air supply unit 13. Therefore, the air sent under pressure from the air supply unit 13 is
Is blown upward from the upper end of the substrate and is blown onto the lower surface of the substrate 6.

A heating wire 14 as a heater is wound around the three upstream nozzles 11 of the four nozzles 11 to heat the air blown out from the nozzles 11.
In FIG. 2, the board 6 is slightly supported at both ends by pins 15 attached to the pair of left and right conveyors 4. Further, the nozzle 11 blows air onto the central portion of the substrate 6 (see the broken line arrow). A roller 16 is provided above the pin 15 to prevent the substrate 6 from being lifted up from the conveyor 4 by the air blown up from the nozzles 11.
It is pressed down (see also Fig. 1).

This reflow apparatus has the above-mentioned structure, and the overall operation will be described below. The substrate 6 on which the electronic component 7 is mounted is conveyed by the conveyor 4 from the inlet 2 to the outlet 3 of the heating chamber 1. Meanwhile, the hot air heated by the heater 8 is blown to heat the solder to a melting temperature or higher, and the solder melts. Then, a relatively low temperature air is blown by the fan 9 at the most downstream side, so that the melted solder is solidified and the electronic component 7 is soldered to the substrate 6.

The substrate 6 softens when heated and bends downward as shown in FIG. 2, but the air blown up from the lower nozzle 11 is blown to the central portion of the lower surface of the substrate 6, so that the substrate 6 Deflection of the board 6 is suppressed, and therefore, both ends of the board 6 do not fall off the pins 15 and the board 6 does not drop from the conveyor 4. If the air blown from the nozzle 11 is heated by the heater 14, the lower surface of the substrate 6 is heated, and the melting of the solder can be further promoted. Further, by pressing both end portions of the substrate 6 against the conveyor 4 by the rollers 16, it is possible to prevent the substrate 6 from being hit by the air blown from below and falling from the conveyor 4.

FIG. 3 is a sectional view of a substrate conveyed by a conveyor of the reflow apparatus according to the second embodiment of the present invention. Since the substrate 6'in this embodiment has a wide width, a plurality of nozzles 11 (three nozzles in this embodiment) are provided in the width direction of the substrate 6 '. Of course, a plurality of substrates 6 ′ are also provided in the carrying direction, as in the case shown in FIG. By disposing a plurality of nozzles 11 in the width direction in this way, a wide substrate 6 '
Can be firmly supported.

Next, a case where electronic components are soldered on both surfaces of the substrate 6'will be described. Some of the boards 6'has electronic components already soldered to the back surface (bottom surface) of the board 6 ', but some of these electronic parts are vulnerable to heat. May be damaged by heat when soldering the electronic components on the upper surface of the substrate 6 '. When soldering an electronic component to the upper surface of the substrate where the electronic component has already been soldered to the lower surface in this manner, the temperature of the air blown out from the nozzle 11 is controlled to 180 ° C. or lower by the heater 14 so that the solder is applied to the lower surface. It is possible to reduce heat damage to the attached electronic component and prevent re-melting of the solder on the lower surface. Thus, the present invention is also effective for soldering a double-sided mounting board.

The present invention is not limited to the above embodiment, and can be applied to, for example, a nitrogen reflow device for sending nitrogen gas to a heating chamber and soldering in the nitrogen gas. The gas blown out from the nozzle 11 is not limited to air, but may be nitrogen gas.

[0018]

As described above, according to the present invention, the gas is blown from the lower side to the central portion of the substrate which is transported while being supported by the conveyor at both end portions, so that the substrate is prevented from being bent downward. This prevents the substrate from falling off the conveyor. Further, by providing a heater in the gas blowing means, the blown gas can be heated and the melting of the solder can be further promoted. Further, by providing the roller, it is possible to prevent the substrate from falling from the conveyor due to the gas blown from below.

[Brief description of drawings]

FIG. 1 is a sectional view showing an internal configuration of a reflow apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a substrate conveyed by a conveyor of the reflow device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a substrate conveyed by a conveyor of a reflow device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating chamber 4 Conveyor 6,6 'Substrate 7 Electronic component 8 Heater 9 Fan 11 Nozzle 14 Heating wire 16 Roller

Claims (3)

[Claims] 1. A reflow provided with a heating chamber, a pair of left and right conveyors arranged inside the heating chamber, and a heater and a fan for heating a substrate which is supported by the conveyor at its both end portions and which is conveyed. A reflow device, characterized in that a gas blowing means for blowing gas from below is provided in a central portion of the substrate conveyed by the conveyor. 2. The reflow apparatus according to claim 1, wherein a heater for heating the gas is provided in the gas blowing means. 3. The reflow apparatus according to claim 1, further comprising rollers for pressing both end portions of the substrate from above to the conveyor.