JP2007059584A - Reflow furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress adverse effect such as failure due to heat in the furnace of an electric motor used to drive a fan for circulating the atmospheric gas in the furnace. <P>SOLUTION: The blower fan 3 provided to each heating zone Z1 to Z8 within the reflow furnace 1 is coupled with the electric motor 5 via a shaft 4, and the motor 5 is covered with an external cover 7. A ventilation duct 10 is provided between a furnace wall 6 and the external cover 7. The ventilation duct 10 is provided, at its inlet port 11, with an electric fan 12 for guiding the external air and this external air is blown to the motor 5 for driving the blower fan 3 through the outlet port 13 of the ventilation duct 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reflow furnace for soldering electronic components mounted on a circuit board via a solder paste.

  A reflow furnace carries a circuit board carrying electronic components into the furnace via a solder paste, and solders the electronic parts to the circuit board by exposing the circuit board to a high-temperature atmosphere in the furnace while moving the circuit board. It is used for.

  Patent Document 1 discloses a typical reflow furnace. As disclosed in Patent Document 1, the reflow furnace has a fan for circulating the internal atmospheric gas, and this fan is driven by an electric motor disposed outside the furnace.

By the way, in the reflow furnace, the temperature profile in the furnace becomes an important control element in order to perform appropriate soldering. The solder used in the reflow furnace tends to use lead-free solder that does not contain lead components in order to eliminate lead (Pb), which is an environmental problem, and lead-free solder has been widely used so far. In many cases, the melting point is higher than that of the solder containing the component. Therefore, when using lead-free solder, a high furnace temperature is set.
Patent document 2004-181383

  As described above, the reflow furnace includes a fan for circulating the atmospheric gas in the furnace. However, when the internal temperature of the reflow furnace is set to a high temperature, the heat in the relatively high temperature furnace is In addition, the heat is transmitted to the electric motor through a shaft connected thereto, and the heat causes a problem that the electric motor breaks down or the life is shortened.

  An object of the present invention is to provide a reflow furnace that can suppress an electric motor that drives a fan from being adversely affected by heat in the furnace, on the premise of a reflow furnace having a fan for circulating atmospheric gas in the furnace. It is to provide.

According to the present invention, such a technical problem is
In a reflow furnace that circulates atmospheric gas in a furnace by a fan for circulation in the furnace driven by an electric motor,
A vent duct having a cool air inlet for receiving cool air, and driving a cool air introducing fan provided in the vent duct to blow cool air around the electric motor through the vent duct to force the electric motor This is achieved by providing a reflow furnace characterized by being air cooled.

  According to this, the electric motor that drives the in-furnace circulation fan is forcibly air-cooled, so that the failure of the electric motor due to heat and the shortening of the life can be suppressed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 3 show a reflow furnace of a first embodiment, FIG. 1 is a side view of the first reflow furnace, FIG. 2 is a plan view, and FIG. 3 is an end view. The illustrated reflow furnace 1 has an inlet on the right side toward the drawing and an outlet on the left side, and a circuit board on which electronic components are mounted via solder paste is directed from right to left by the same means as in the past. Be transported.

  The tunnel part 2 constituting the heating part of the reflow furnace 1 is partitioned into a plurality of heating zones Z1 to Z8 toward the circuit board transport direction X. A blower fan 3 is disposed above each heating zone Z1 to Z8, and a heater (not shown) is disposed adjacent to each blower fan 3. In order from the inlet side, the first to fifth zones Z1 to Z5 are preheating zones, and the sixth to eighth zones Z6 to Z8 are main heating zones. The internal atmosphere gas of the reflow furnace 1 is composed of air or an inert gas, the internal atmosphere gas is circulated by the blower fan 3 for each heating zone, and the temperature is controlled for each heating zone.

  Each blower fan 3 is connected to an electric motor 5 through a shaft 4, and the blower fan 3 is driven when the electric motor 5 rotates. The blower fan electric motor 5 is disposed outside the furnace wall 6 and inside the outer cover 7, and the electric motor 5 is surrounded by the outer cover 7. The reflow furnace 1 is installed on the floor 9 via the support column 8, and the outer cover 7 is opened downward, that is, toward the floor 9.

  In the figure, reference numeral 10 indicates a ventilation duct. In the embodiment, the ventilation duct 10 includes first and second ventilation ducts 10 </ b> A and 10 </ b> B, and the first and second ventilation ducts 10 </ b> A and 10 </ b> B are disposed inside the outer cover 7. Here, the first ventilation duct 10A is for the first to fourth zones Z1 to Z4, and the second ventilation duct 10B is for the fifth to eighth zones Z5 to Z8. The first and second ventilation ducts 10A and 10B both have inlets 11A and 11B in the central portion, and outside air is introduced as cool air into the first and second ventilation ducts 10A and 10B through the inlets 11A and 11B. The Each inlet 11A, 11B, that is, a cool air inlet for receiving cool air is opened upward, and each inlet 11A, 11B is provided with an electric fan 12A, 12B for introducing cool air, The electric fans 12A and 12B forcibly introduce cool air into the first and second ventilation ducts 10A and 10B.

  The first ventilation duct 10 </ b> A extends over a total of four electric motors 5 in the first to fourth zones Z <b> 1 to Z <b> 4, and first to fourth outlets opened laterally toward the side surfaces of the electric motors 5. 13a to 13d. Similarly, the second ventilation duct 10 </ b> B extends over a total of four electric motors 5 in the fifth to eighth zones Z <b> 5 to Z <b> 8 and opens to the side surfaces of the respective electric motors 5 to 8th to 8th outlets. 13e-13h. In the figure, reference numeral 15 indicates a support column, and the first and second ventilation ducts 10 </ b> A and 10 </ b> B are fixed to the ceiling wall of the furnace wall 6 through the support column 15.

  The first and second ventilation ducts 10A and 10B including the electric fans 12A and 12B described above are electric motors 5 for driving the blower fans 3 disposed in the first to eighth heating zones Z1 to Z8. Constitutes a system for air cooling. That is, outside air as forced air is forcibly introduced into the first and second ventilation ducts 10A and 10B by the electric fans 12A and 12B, and the outside air introduced into the ventilation ducts 10A and 10B is supplied to the electric motors 5. Each electric motor 5 is forcibly air-cooled by being sprayed around the.

  Therefore, the influence of the electric motor 5 due to the heat of the high-temperature internal atmosphere gas in each of the heating zones Z1 to Z8 being transmitted to the electric motor 5 by the furnace wall 6, the blower fan 3, and the drive shaft 4 with the use of lead-free solder. That is, the conventional problem that the electric motor 5 for driving the blower fan 3 fails due to heat or the life is shortened by blowing cool air to each electric motor 5 through the air duct 10 to cool it by air. Can be resolved.

  The reflow furnace 1 of the first embodiment is of a type that circulates while heating the internal atmospheric gas in each of the heating zones Z1 to Z8 by the heater and the blower fan 3 installed in the upper part. As illustrated, a second embodiment is shown in which heaters and blower fans 3 are arranged above and below each of the heating zones Z1 to Z8. 4 is a side view of the second reflow furnace, FIG. 5 is an end view, and FIG. 6 is a bottom view.

  The reflow furnace 30 of the second embodiment has a configuration that is also disposed above the reflow furnace 1 of the first embodiment described above, in the lower part of each heating zone Z1 to Z8. And each blowing outlet of 1st, 2nd ventilation duct 10A, 10B containing electric fan 12A, 12B arrange | positioned at the lower part of the reflow furnace 30 is opened toward the corresponding electric motor 5. As shown in FIG. The first and second ventilation ducts 10A and 10B both have inlets 11A and 11B in the central portion, and outside air is supplied as cool air to the first and second ventilation ducts 10A and 10B through the inlets 11A and 11B. be introduced. That is, each inlet 11A, 11B, that is, a cool air introduction opening is opened downward, and the outside air enters the outer cover 7 through a gap between the lower end of the outer cover 7 opened downward and the floor 9. The air is introduced into the ventilation ducts 10A and 10B through the inlets 11A and 11B, and is discharged toward the electric motors 5 through the ventilation ducts 10A and 10B. Thereby, even in the reflow furnace 30 of the second embodiment, both the electric motor 5 disposed in the upper part and the electric motor 5 disposed in the lower part are air-cooled.

  In the first and second embodiments described above, the example in which the electric motor 5 is disposed inside the outer cover 7 has been shown. However, even when the electric motor 5 is disposed outside the outer cover 7. It is preferable to forcibly cool the electric motor 5 with air. This is illustrated in FIG. In the reflow furnace 40 of the third embodiment shown in FIG. 7, the electric motor 5 is installed in a state where a part of the electric motor 5 protrudes upward from the ceiling wall of the outer cover 7 and is exposed to the outside. The first and second ventilation ducts 10A and 10B are installed on the ceiling wall of the outer cover 7, and the electric fans 12A and 12B of the first and second ventilation ducts 10A and 10B are driven. The cool air is blown around the electric motors 5 through the first and second ventilation ducts 10A and 10B, whereby the electric motors 5 are forcibly cooled by air.

It is a side view of the reflow furnace of 1st Example. It is a top view of the reflow furnace of 1st Example. It is an end view of the reflow furnace of the first embodiment. It is a side view of the reflow furnace of 2nd Example. It is an end elevation of the reflow furnace of the second embodiment. It is a bottom view of the reflow furnace of 2nd Example. It is a side view of the reflow furnace of 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reflow furnace 2 Tunnel part 3 Blower fan 4 Shaft 5 Electric motor 6 Furnace wall 10 Ventilation duct 11 Duct inlet 12 Electric fan for cool air introduction

Claims (1)

In a reflow furnace that circulates atmospheric gas in a furnace by a fan for circulation in the furnace driven by an electric motor,
A vent duct having a cool air inlet for receiving cool air, and driving a cool air introducing fan provided in the vent duct to blow cool air around the electric motor through the vent duct to force the electric motor Reflow furnace characterized by air cooling.

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