JPH09237965A - Reflow furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reflow solder electronic components surely and rigidly to a board only by setting the temperature in a furnace at a specified value, by arranging a heating zone where hot gas makes convection in the length direction of the furnace main body and a heating zone where hot gas makes convection in the width direction of the furnace main body. SOLUTION: A hot gas jetting nozzle 7 is positioned on the upper surface of the inlet side of a furnace main body 1, and jetted hot gas makes convection in the length direction of the furnace main body 1. A suction duct 8 is positioned between a second preheat zone and a reflow zone, and the hot gas jetted from the nozzle 7 circulates from the suction duct 8 to a blower 4. A hot gas jetting nozzle 12 is positioned between small-sized infrared heaters 3, 3 which are arranged at specified intervals in the reflow zone, in the transversal direction on both sides of the center line in the substrate carriage direction. The hot gas jetted from the hot gas nozzle 12 is dispersed in the direction of furnace main body width and makes convection. The hot gas jetted from a hot gas duct 12 circulates from suction ducts 13, 13 arranged on both ends in the width direction of the furnace main body 1 to a blower 9.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a reflow furnace.

[0002]

2. Description of the Related Art A conventional reflow furnace, as shown in FIG. 10, includes a plurality of small infrared heaters (plane heaters) 21 and 21 provided in a plurality of divided heating zones constituting a preheat zone and a reflow zone. The electronic component mounting board 15 is heated by the hot air blown downward between the infrared heaters 21 and 21 or from a small diameter hole arranged in a row on the infrared radiation surface (not shown), and the electronic components are mounted on the board by soldering. Was configured into.

Further, as shown in FIG. 11, a large infrared heater (surface heater) 2 is provided in a plurality of divided heating zones which constitute a preheat zone and a reflow zone.
There is known a reflow furnace configured to heat the electronic component mounting substrate 15 with 2 ... 22 and hot air convection along the substrate transporting direction and solder the electronic components on the substrate.

[0004]

However, a plurality of small infrared heaters 21, 21 provided in each zone and the infrared heaters 21, 21 are blown downward between the infrared heaters 21, 21 or from small-diameter holes arranged in a row on the infrared radiation plate. In a reflow furnace configured to heat the substrate 15 on which electronic components are mounted with hot air, it is difficult to control the radiant heating temperature because many small infrared heaters (surface heaters) are required.
Furthermore, the infrared heater 2 can be used depending on the temperature and speed of the hot air.
1 and the infrared radiation plate are affected, it is difficult to control the temperature in the furnace.

In addition, in a reflow furnace configured to heat the substrate 15 on which electronic components are mounted by the large-sized infrared heaters 22 provided in each zone and hot air convection along the substrate transport direction. Is that the wind velocity at the central portion in the longitudinal direction of the substrate 15 is high, the temperature at the central portion in the longitudinal direction of the substrate 15 becomes high, and the temperature at both end portions becomes low. There is a problem, and as shown in FIG. 11, convection of hot air along the substrate transport direction makes it easy for the outside air to be sucked into the interior of the furnace body from the inside, reducing the thermal efficiency in the furnace. However, there is a problem that the air in the furnace, which is contaminated by the flux or the like, is easily discharged to the outside of the furnace because the air is blown out.

An object of the present invention is to provide a reflow furnace which can securely and firmly mount electronic components on a substrate by reflow soldering by an extremely simple operation of setting the temperature inside the furnace to a predetermined temperature. .

[0007]

SUMMARY OF THE INVENTION The present invention is a reflow oven for soldering and mounting electronic components on a substrate by an infrared heater provided in a plurality of divided heating zones and convection of hot air. A heating zone where convection occurs,
A heating zone where hot air convection is provided in the width direction of the furnace body.

The substrate is uniformly heated in the vertical and horizontal directions by the heating zone where hot air is convected in the longitudinal direction of the furnace body and the heating zone where hot air is convected in the width direction of the furnace body. Therefore, it is possible to securely and firmly mount the electronic component on the substrate by reflow soldering by an extremely simple operation of setting the temperature inside the furnace to a predetermined temperature.

Further, as described in claim 2, the convection direction of the hot air in the heating zone at the frontmost end of the furnace main body is set in the longitudinal direction of the furnace main body and in the opposite direction to the substrate transfer direction. It is possible to effectively prevent the outside air being sucked into the main body from lowering the thermal efficiency in the furnace. In addition, if the heating zones in which the convection direction of the hot air is the longitudinal direction of the furnace main body and the substrate conveying direction are arranged in parallel, the substrate is heated very efficiently and uniformly over the entire surface by the hot air from the front-back direction and the lateral direction.

Furthermore, by setting the convection direction of the hot air in the final heating zone to be the width direction of the furnace body as described in claim 3, it is extremely possible that the air inside the furnace contaminated by flux or the like is diffused outside the furnace. It can be effectively prevented.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is an explanatory view showing a first embodiment of the present invention, and FIG. 2 is an explanatory view showing a convection state of hot air.
In FIG. 1, 1 is a furnace main body, and the inside of the furnace main body 1 is divided into a first preheat zone, a second preheat zone, and a reflow zone from the inlet side. Reference numeral 2 is a large infrared heater (surface heater) provided on the upper surfaces of the first preheat zone and the second preheat zone, and 3 and 3 are small infrared heaters (surface heater) provided in the reflow zone. As shown in the drawing, 3 are provided at predetermined intervals in the lateral direction with the center line in the substrate transport direction sandwiched therebetween. Reference numeral 4 denotes a blower, 5 denotes a duct connecting the blower 4 and a heater 6 described later, 6 denotes a heater, and the heater 6 heats air blown from the blower 4. Reference numeral 7 denotes a hot air blowing nozzle. The hot air blowing nozzle 7 is located on the inlet side upper surface of the furnace body 1, and the hot air blown out convects in the furnace body longitudinal direction (substrate transfer direction). Reference numeral 8 denotes an intake duct, which is located between the second preheat zone and the reflow zone, and the hot air blown from the hot air blowing nozzle 7 is returned from the intake duct 8 to the blower 4. Reference numeral 9 is a blower, 10 is a duct connecting the blower 9 and a heater 11 described later, 11 is a heater, and the heater 11 heats the air blown from the blower 9. Reference numeral 12 is a hot air blowing nozzle. The hot air blowing nozzle 12 is located between the small infrared heaters 3 provided laterally at a predetermined interval in the reflow zone with a center line in the substrate transfer direction interposed therebetween. The hot air blown out of the furnace disperses and convects in the width direction (horizontal direction of the substrate) of the furnace body. Intake ducts 13 and 13 are provided at both ends of the furnace body 1 in the width direction. The hot air convection in the furnace body width direction (substrate lateral direction) in the reflow zone may be convected from one side surface of the furnace body 1 to the other side surface. Reference numeral 14 is a conveyor that conveys a substrate 15 on which electronic components are mounted into the furnace body 1.

In order to reflow-solder the electronic components mounted on the board by the reflow furnace of the present invention having the above-described structure, the board 15 on which the electronic components are mounted is set on the conveyor 14 and conveyed into the furnace body 1. To do. The substrate 15 transferred into the furnace body 1 is an infrared heater 2 provided in each zone,
3, the entire surface is uniformly heated in the vertical and horizontal directions by the hot air convection in the longitudinal direction of the furnace body (the substrate carrying direction) and the hot air convection in the width direction of the furnace body, and the electronic components are securely and firmly soldered and mounted on the substrate 15. Therefore, it does not require any troublesome temperature adjustment as in the prior art, and the electronic components can be reliably and firmly reflow-soldered to the substrate by an extremely simple operation of setting the temperature inside the furnace to a predetermined temperature. Moreover, since hot air is convection in the width direction of the furnace body in the reflow zone, it is possible to very effectively prevent the air contaminated by the flux or the like from escaping outside the furnace.

In the first preheat zone and the second preheat zone, the hot air is convected in the longitudinal direction of the furnace body 1 (the substrate carrying direction), so that the outside air is easily sucked into the furnace body. By setting the temperature inside the furnace to a predetermined temperature in consideration of the above, it is possible to securely and firmly reflow solder the electronic component to the substrate without any problem.

FIGS. 3 and 4 are an explanatory view showing a second embodiment of the present invention and an explanatory view showing a convection state of hot air.
In this embodiment, the hot air blowing nozzle 7 for blowing hot air heated by the heater 6 is located between the infrared heaters (surface heaters) 2 provided in the first preheat zone and the second preheat zone, and the hot air blowing nozzle In the first preheat zone, the hot air blown from 7 is convected in the direction opposite to the substrate transport direction to recirculate from the intake duct 8 located at the inlet end of the furnace body 1 to the blower 4, and in the second preheat zone, the substrate transport direction. To the blower 4 from the intake duct 8 located between the second preheat zone and the reflow zone, and in the reflow zone, the hot air blowing nozzle 12 that blows out the hot air heated by the heater 11 is used for infrared rays. Heater (surface heater) 3,
The reflow furnace is located between the three hot air blowing nozzles 12 so as to convect the hot air blown from the hot air blowing nozzle 12 in the width direction of the furnace body (lateral direction of the substrate) and to recirculate the hot air from the intake ducts 13 and 13 to the blower 9. . In the figure, 5 indicates a duct connecting the blower 4 and the heater 6, and 10 indicates a duct connecting the blower 9 and the heater 11.

By configuring the reflow furnace as described above, the substrate carried into the furnace body 1 by the conveyor 14 receives hot air from the front in the first preheat zone,
Since the second preheat zone receives hot air from the rear and the reflow zone receives hot air from the lateral direction, the substrate is heated very efficiently and uniformly over the entire surface in the front-rear direction and the lateral direction. The electronic component can be securely and firmly reflow-soldered to the board by an extremely simple operation of setting the temperature to. Further, in the first preheat zone, hot air is convected in the direction opposite to the substrate transport direction, so that the invasion of outside air into the furnace body 1 can be very effectively prevented.

The present invention is not limited to the above-described embodiment, and as shown in FIG. 5, hot air is convected in the substrate transport direction in the first preheat zone and the substrate transport direction in the second preheat zone. You may make hot air convection in the opposite direction.

Further, as shown in FIG. 6, hot air is convected in the width direction of the furnace body in the first preheat zone, hot air is convected in the substrate transfer direction in the second preheat zone, and in the reflow zone in the direction opposite to the substrate transfer direction. You may make hot air convection. At this time, in the preheat zone in which hot air is convected in the width direction of the furnace body (horizontal direction of the substrate), as described above, the small infrared heaters 3, 3 are provided at predetermined intervals in the lateral direction with the center line in the substrate transport direction interposed therebetween. A hot air blowing nozzle is positioned between the infrared heaters 3 to allow hot air to convect in the width direction of the furnace body.

Further, as shown in FIG. 7, in the first preheat zone, hot air is convected in the width direction of the furnace body, and in the second preheat zone, hot air is convected in the direction opposite to the substrate carrying direction.
In the reflow zone, hot air may be convected in the substrate transfer direction.

Further, as shown in FIG. 8, when the preheat zone is divided into two or more sections, heating zones convection in the longitudinal direction of the furnace body are intermittently provided in the first preheat zone and the third preheat zone. You may do it.

Furthermore, as shown in FIG. 9, in the first preheat zone, hot air may be convected in the direction opposite to the substrate transport direction, and after the second preheat zone, hot air may be convected in the substrate transport direction. As shown, the infrared heater 2 provided in the first preheat zone, the infrared heaters 3 and 3 provided in the reflow zone, and the conveyor 14 (see FIG. 1).
Infrared heaters (planar heaters) 2a and 2a are provided to face each other with the heater sandwiched therebetween, or not limited thereto, and the infrared heaters 2 and the conveyor 14 provided in each preheat zone as necessary.
The infrared heaters 2a may be provided so as to face each other with the heating heater interposed therebetween, and the heating zone where hot air is convected in the longitudinal direction of the furnace body and the heating zone where hot air is convected in the width direction of the furnace body are provided in the above-described embodiment. It is not limited to the form,
It goes without saying that the design can be changed as needed.

[0021]

As described above, according to the present invention, the electronic components can be surely and firmly reflow-soldered and mounted on the board by an extremely simple operation of setting the temperature in the furnace to a predetermined temperature. Instead, by setting the convection direction of the hot air in the heating zone at the front end of the furnace main body to be the longitudinal direction of the furnace main body and the direction opposite to the substrate transfer direction, the outside air is sucked into the furnace main body 1 and the thermal efficiency in the furnace is increased. Can be effectively prevented from falling, and by setting the convection direction of the hot air in the final heating zone to be the width direction of the furnace body, it is possible to prevent the air inside the furnace contaminated with flux from being discharged outside the furnace. There are excellent advantages such as very effective prevention.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a convection state of hot air according to the first embodiment.

FIG. 3 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a convection state of hot air according to the second embodiment.

FIG. 5 is an explanatory diagram showing a convection state of hot air in another embodiment of the present invention.

FIG. 6 is an explanatory view showing a convection state of hot air according to another embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a convection state of hot air according to another embodiment of the present invention.

FIG. 8 is an explanatory view showing a convection state of hot air according to another embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a convection state of hot air in another embodiment of the present invention.

FIG. 10 is an explanatory view showing a conventional reflow furnace.

FIG. 11 is an explanatory diagram showing a convection state of hot air in a conventional reflow furnace.

[Explanation of symbols]

1 furnace body
2 Infrared heater 3 Infrared heater

Claims (3)

[Claims] 1. A reflow furnace in which an electronic component is soldered and mounted on a substrate by an infrared heater provided in a plurality of divided heating zones and convection of hot air, and a heating zone in which hot air is convected in the longitudinal direction of the furnace body, and a furnace A reflow furnace characterized by having a heating zone in which hot air is convected in the width direction of the main body. 2. The reflow furnace according to claim 1, wherein the convection direction of the hot air in the heating zone at the most front end of the furnace body on the inlet side is the longitudinal direction of the furnace body and the direction opposite to the substrate conveying direction. 3. The reflow furnace according to claim 1, wherein the convection direction of the hot air in the final heating zone is the width direction of the furnace body.