JPH0687069A - Gas sealing reflowing device - Google Patents

Abstract

PURPOSE:To efficiently discharge waste gas and easily control to keep a constant low density in a tunnel by providing a gas discharging port from which the atmospheric gas in the tunnel is discharged at the lower part of the tunnel. CONSTITUTION:The gas for making a gas curtain in the tunnel 1 is sent by a gas curtain device 6 to form the gas curtain and the low temperature outside air entering from the entrance and exit of the tunnel is shielded by the gas curtain. A slightly entering air is discharged from an entering outside air discharging port 5b provided at the lower part of the tunnel in the vicinity of the gas curtain. The gas containing much oxygen in the tunnel is heavier than an inert gas or reduction gas and stagnates in a lower layer part in the tunnel and is discharged from an inside gas in the tunnel discharging port 5a. Thus, the atmosphere in the tunnel 1 is kept in a certain condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow apparatus containing an inert gas and a reducing gas.

[0002]

2. Description of the Related Art The structure of a conventional gas-filled reflow apparatus will be described below with reference to the schematic sectional view shown in FIG.

The apparatus main body is provided with a tunnel 31 having a space in which a predetermined gas atmosphere is formed, and far infrared panel heaters 32a and 32b are installed on the upper surface and the lower surface inside the tunnel 31, respectively. A belt conveyor 33 for conveying members is installed on the far infrared panel heater 32a.

A replacement gas injection port 34 is provided in the upper and lower portions of the central portion of the tunnel 31, and an inert gas or a reducing gas such as nitrogen gas, hydrogen gas or nitrogen-hydrogen forming gas is supplied to the atmosphere inside the tunnel from there. Inject and replace. A gas discharge port 35 for discharging the atmosphere gas inside the tunnel is provided above each of the tunnel entrance and exit. Further, in order to maintain a low concentration of oxygen in the atmosphere inside the tunnel, a gas curtain device 36 for blocking the outside air using an inert gas such as nitrogen gas is provided at the upper and lower portions of the entrance and the exit on both sides of the tunnel.

When brazing is performed using a solder material using the apparatus having such a structure, as shown in FIG. 4, an inert gas or a reducing gas 37 is injected from the replacement gas injection port 34, and the gas is exhausted. The gas inside the tunnel is discharged from the outlet 35. Further, in the gas atmosphere in the tunnel 31, the entering outside air 39 and the gas 40 containing a large amount of oxygen have a larger mass than the inert gas or the reducing gas, so that they easily accumulate in the lower layer portion in the tunnel 31, while The inert gas or reducing gas 37 is likely to collect in the upper layer portion in the tunnel 31.

[0006]

By the way, when soldering is performed using a solder material in the above-mentioned inert gas or reducing gas type reflow apparatus (hereinafter referred to as a reflow furnace),
Soldering is often performed at a high temperature of 200 ° C. to 400 ° C. In order to prevent defects caused by oxidation and perform good soldering, the oxygen concentration in the tunnel atmosphere is set to a certain level or less, Therefore, it is necessary to suppress the oxygen concentration to around 100 ppm.

However, as described above, in the conventional technique,
Since the gas outlet of the atmosphere inside the tunnel is located in the upper part of the tunnel, an inert gas or reducing gas lighter than oxygen is likely to accumulate in the upper layer of the tunnel and is easily discharged from the gas outlet. Oxygen gas tends to collect in the lower layer of the tunnel, and is difficult to be discharged from the discharge port provided above, which causes a problem that it is difficult to control the oxygen concentration. Therefore, in order to control the oxygen concentration below a certain level in this device, a large amount of inert gas or reducing gas needs to be filled, which is a factor of increasing the cost. Further, when the gas flow rate increases, the atmosphere in the tunnel is cooled by the supplied gas, the temperature distribution in the tunnel becomes uneven, and it becomes difficult to control the temperature in the tunnel. As a countermeasure, extra equipment such as a heater for an inert gas or a reducing gas must be provided. However, in such equipment, the gas heating level has a limit, which is not very effective.

The outside air entering from the outside of the tunnel is also considerably lower than the temperature of the atmosphere inside the tunnel (usually around 25 ° C.), so that it is likely to remain in the lower layer of the tunnel, and the outlet is located above the tunnel. Therefore, it was difficult to be discharged to the outside, which was a factor to make it difficult to create a low oxygen concentration atmosphere.

The present invention has been made in order to solve the above problems, and efficiently discharges the atmosphere containing much oxygen in the lower layer portion of the tunnel, and the inert gas or the inert gas injected into the tunnel. Prevent outflow of reducing gas,
An object of the present invention is to provide a gas-filled reflow device that can easily control the oxygen concentration and temperature inside the tunnel.

[0010]

In order to achieve the above object, a gas filled reflow apparatus of the present invention is a tunnel having a predetermined gas atmosphere and having a space for performing reflow in the atmosphere. And a gas injection port for injecting an inert gas or a reducing gas into the tunnel, and a gas exhaust port for exhausting the gas in the tunnel. Is provided under the tunnel.

[0011]

The gas containing a large amount of oxygen, which is larger than the inert gas or the reducing gas (hydrogen gas, nitrogen gas, hydrogen forming gas, etc.), is efficiently discharged from the gas discharge port provided under the tunnel. Further, the incoming outside air having a temperature lower than that of the gas atmosphere in the tunnel is also discharged from the gas discharge port provided in the lower part of the tunnel. Therefore, it is not necessary to inject a large amount of inert gas or reducing gas, and the oxygen concentration and temperature inside the tunnel can be maintained at a constant level.

[0012]

1 is a schematic sectional view of an embodiment of the present invention. Embodiments of the present invention will be described below with reference to the drawings.

The apparatus body is provided with a tunnel 1 having a space in which a gas atmosphere is formed.
Far-infrared panel heaters 2a and 2b are installed on the upper and lower surfaces inside, respectively, and a belt conveyor 3 for conveying members is installed on the far-infrared panel heater 2a on the lower surface side.

A replacement gas injection port 4 is provided in the upper and lower portions of the central part of the tunnel 1, and an inert gas or a reducing gas such as nitrogen gas, hydrogen gas or nitrogen-hydrogen forming gas is supplied to the tunnel internal atmosphere. Inject and replace. A tunnel internal gas exhaust port 5a for exhausting the atmosphere gas inside the tunnel is provided at the lower portion of each of the tunnel inlet and outlet, and an exhaust fan 11 is installed at the tip end thereof. This exhaust fan 11
Thus, the discharge amount of the atmospheric gas inside the tunnel 1 is adjusted according to the oxygen concentration inside the tunnel 1. Also, tunnel 1
In order to maintain the airtightness of the inside, a gas curtain device 6 for blocking the outside air using an inert gas such as nitrogen gas is provided at the upper and lower portions of the inlet and the outlet on both sides of the tunnel. Further, an entrance outside air discharge port 5b is provided in the lower part of the inside (tunnel side) of the curtain device 6.

The operation of the reflow apparatus of the embodiment of the present invention having the above construction will be described below with reference to the diagram showing the state of gas convection inside the tunnel shown in FIG. The gas curtain device 6 sends the gas curtain injection gas 8 into the tunnel 1 to form a gas curtain, and the outside air 9 having a low temperature and entering from the entrance and the exit of the tunnel 1 is substantially blocked by the gas curtain. However, the entering outside air 9 that slightly enters is discharged from the entering outside air discharge port 5b provided in the lower portion of the tunnel 1 near the gas curtain device 6, and airtightness is maintained. An inert gas such as nitrogen is used for this gas curtain. In addition, the gas containing much oxygen in the tunnel 1
0 has a heavier mass than an inert gas or a reducing gas, accumulates in the lower layer of the tunnel 1, and the gas outlet 5 inside the tunnel
It is discharged from a. Further, since the internal injection gas 7 injected from the replacement gas injection port 4 is lighter than the gas 10 containing a large amount of oxygen, it is in a state of being accumulated in the upper layer portion in the tunnel 1. Therefore, the internal injection gas 7 accumulated in this upper layer portion
Is in a confined state, and it is difficult to discharge it to the outside, and there is no loss such that the internal injection gas 7 is additionally required.

In this way, the entering outside air 9 that slightly enters is easily discharged from the entering outside air discharge port 5b, the entrance of the entering outside air 9 can be almost completely blocked, and the gas atmosphere inside the tunnel 1 is almost affected by the temperature. Since it is possible to easily control the oxygen concentration inside the tunnel 1, the atmosphere inside the tunnel 1 can be kept constant.

Therefore, when soldering is performed using the reflow apparatus according to the embodiment of the present invention, variations in soldering can be suppressed and good soldering can be performed.

[0018]

As described above, according to the gas filled type reflow apparatus of the present invention, the gas discharge port for discharging the atmospheric gas in the tunnel is provided in the lower portion of the tunnel.
It is possible to prevent outflow of an inert gas or a reducing gas having a smaller mass than oxygen from the inside of the tunnel, and it is possible to efficiently discharge a gas in an atmosphere containing a large amount of oxygen gas accumulated in the lower portion of the tunnel. Therefore, it becomes easy to control the inside of the tunnel to a constant low concentration,
Also, the temperature control inside the tunnel becomes easy.
As a result, the state of the atmosphere inside the tunnel becomes constant, variations in soldering can be suppressed, and highly reliable soldering becomes possible, improving the performance and reliability of the device. Furthermore, a large amount of inert gas or reducing gas is not required, and running costs can be suppressed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is an explanatory view of the operation of the embodiment of the present invention.

FIG. 3 is a schematic sectional view of a conventional example.

FIG. 4 is an operation explanatory view of a conventional example.

[Explanation of symbols]

 1 ... Tunnel 2 Far infrared panel heater 3 Belt conveyor 4 Replacement gas inlet 5a Tunnel internal gas outlet 5b Ingress outside air exhaust Outlet 6 ... Inert gas curtain device 7 ... Internal injection gas 8 ... Injection gas for gas curtain 9 ... Ingress outside air

Claims (1)

[Claims] 1. A tunnel in which a predetermined gas atmosphere is formed and has a space for performing reflow in the atmosphere, a gas injection port for injecting an inert gas or a reducing gas into the tunnel, and A gas-filled reflow device having a gas discharge port for discharging gas in a tunnel, wherein the gas discharge port is provided at a lower portion of the tunnel.