JP4271299B2 - Reflow furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflow furnace in which a housing is divided into upper and lower parts.
[0002]
[Prior art]
For example, when various devices are mounted on a printed circuit board, a soldering process generally called a solder reflow process is performed using a reflow furnace.
In the above reflow furnace, the furnace air heated by the heater provided in the furnace is forcibly agitated by a fan provided in the furnace in order to keep the entire furnace uniformly heated to the welding temperature of the solder. To be done.
In order to facilitate maintenance, the reflow furnace employs a structure in which a heat-insulating upper housing is detachably superposed on an upper part of a heat-insulating lower housing. The furnace air is sealed so as not to leak to the outside. As this sealing means, a foamed silicon packing is used, and this packing is inserted between the overlapping surfaces of the upper housing and the lower housing.
[0003]
[Problems to be solved by the invention]
However, in the conventional reflow furnace, the packing is placed between the overlapping surfaces of the lower housing and the upper housing and is pressed from above and below to be sealed, so the side surface of the packing is the packing of the overlapping surface. It is in direct contact with the furnace air entering through the gap corresponding to the thickness. For this reason, the flux fume gas generated when the solder melts contacts the packing together with the air in the furnace and corrodes it. Moreover, the temperature of packing rises to 250-260 degreeC more than heat-resistant temperature by the contact of the air in a furnace, and the heat transfer from the overlapping surface of a housing. If the packing deteriorates due to the above causes and the seal of the upper and lower overlapping parts is damaged, gas leaks to the outside. In order to prevent this leakage, there is a problem that the packing must be replaced at an early stage.
In view of the above-described conventional problems, an object of the present invention is to provide a reflow furnace in which a housing with little packing deterioration is divided into upper and lower parts.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, a reflow furnace according to the present invention is configured such that an upper housing having a heat insulating material is detachably overlapped on an upper portion of a lower housing having a heat insulating material, and air in the furnace leaks from the overlapping surfaces of these housings. In the reflow furnace that is prevented by packing,
An outwardly extending lower collar portion formed outside the overlapping surface of the lower housing and outside the heat insulating material, and an outside formed outside the overlapping surface of the upper housing and outside the heat insulating material. by an upper flange portion extending towards said annular holding portion which opens outwardly of the furnace body outside of the heat insulating material is constituted, it was superposed surface and adhered overlapping surfaces and each other of the lower housing of the upper housing together is, the packing is held between the annular holding portion in a state in which a gap between its outer surface a whole or one prior Symbol insulation material is exposed to the outside, that between the two housings is sealed It is characterized by.
According to the reflow furnace having the above configuration, the overlapping surfaces are brought into close contact with each other, and the packing is provided outside the overlapping surfaces, so that the furnace air containing the gas generated from the flux or the like is directly applied to the packing. The contact can be suppressed. Further, the annular holding portion configured packing in the upper and lower flange portion of the outside of each housing, the sandwich in a state where a gap between its outer surface a whole or One prior Symbol insulation material is exposed to the outside The heat conduction from the housing to the packing is small, and the heat applied to the packing is easily dissipated. For this reason, the temperature rise of packing is suppressed. In particular, since the packing does not directly contact the side wall of the housing, temperature rise due to heat transfer from the side wall is prevented.
[0005]
In the reflow furnace, it is preferable that the outer plate of each housing has a plurality of ventilation holes, and a gap is provided between the outer plate and the heat insulating material.
In this case, an air layer can be provided in the gap between the heat insulating material of the housing and the outer plate, and the air heated in this gap can be replaced with outside air through the ventilation holes provided in the outer plate. The temperature rise of the packing can be further suppressed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an embodiment of a reflow furnace according to the present invention.
The reflow furnace of the present invention includes a furnace body R divided into an upper housing 1 and a lower housing 2, a heater 7 for raising the temperature of the furnace air, and a furnace for uniformly raising the temperature inside the furnace. A fan 4 that stirs the internal air, a motor 5 that rotates the fan 4, a packing 3 that prevents the air in the furnace from leaking outside the furnace body R, and a chain conveyor 6 that conveys the substrate A to be heated. The main part is composed of.
[0008]
The housings 1 and 2 constituting the furnace body R have a heat insulating structure in which heat insulating materials 12 and 22 such as glass wool are sandwiched between the metal plates 10 and 20, and the upper housing 1 is separated on the lower housing 2. Overlapping is possible. The overlapping surfaces 1a and 2a of the upper housing 1 and the lower housing 2 are smooth surfaces and are overlapped with each other.
[0009]
The outer plates 13 and 23 of the side walls 11 and 21 of the upper housing 1 and the lower housing 2 are disposed with a gap between the side surfaces of the heat insulating materials 12 and 22, respectively. For this reason, in addition to the heat insulating materials 12 and 22, the side walls 11 and 21 have a double structure in which an air layer B is provided outside thereof. The outer plates 13 and 23 are provided with a plurality of ventilation holes 13a and 23a for replacing the air layer B with outside air.
An upper flange portion 1b and a lower flange portion 2b extending outward are provided at positions close to the overlapping surfaces 1a and 2a of the upper housing 1 and the lower housing 2, and the outer plates 13 and 23 are provided at the distal end portions. It is connected.
[0010]
The upper flange portion 1b and the lower flange portion 2b are provided over the entire overlapping portion of the furnace body R in a state of being close to each other , and an annular holding portion that opens to the outside of the furnace body is formed by both. The furnace body R is sealed with the packing 3 sandwiched between the annular holding portions. The upper and lower flange portions 1b and 2b are formed continuously with the metal plates 10 and 20 on the inner surfaces of the housings 1 and 2 in the figure. The packing 3 is a foamed silicon rubber ring, and is disposed with a gap between the lower side surfaces of the side walls 11 and 21 of the housings 1 and 2.
[0011]
A fan 4 is provided in the upper part of the furnace of the upper housing 1, and a heater 7 is provided below the fan 4. The fan 4 is connected to a motor 5 fixed to the outside of the upper housing 1. The heater 7 can heat the furnace air by energization. For this reason, the hot air circulation path a is formed by circulating the furnace air heated by the heater 7 by the fan 4. Accordingly, the substrate A to be heated is heated by hot air while being conveyed by the chain conveyor 6 provided inside the lower housing 2 below the heater 7.
[0012]
If it is the said structure, the temperature in furnace can be heated up with the heater 7, this furnace air can be stirred with the fan 4, and the inside of a furnace can be circulated along the hot air circulation path | route a. At this time, since the overlapping surface 1a of the upper housing 1 and the overlapping surface 2a of the lower housing 2 are brought into close contact with each other and the packing 3 is provided outside the furnace body R, the flux fume gas generated when the solder is melted is removed. It is possible to prevent the in-furnace air contained from coming into direct contact with the packing 3. For this reason, it can suppress that the packing 3 heats up with furnace air, or the packing 3 corrodes with the said gas.
In addition, since the packing 3 is attached to the housings 1 and 2 via the upper and lower flange portions 1b and 2b, it is possible to prevent the packing 3 from being heated by heat transfer from the housings 1 and 2. Particularly in this embodiment, since a gap is provided between the side walls 11 and 21 and the packing 3, it is more effective that the temperature of the packing 3 is raised by heat transfer from the side walls 11 and 21. It is suppressed. In addition, the air in the air layer B between the heat insulating materials 12 and 22 and the outer plates 13 and 23 is replaced with the outside air by the ventilation holes 13a and 23a provided in the outer plates 13 and 23. The temperature can be further suppressed. Therefore, the inside of the furnace can be maintained in a sealed state by the flange portions 1b and 2b and the packing 3, and the packing 3 is not deteriorated.
[0013]
【The invention's effect】
As described above, according to the reflow furnace according to the first aspect, the furnace air containing the flux fume gas generated when the solder is melted can be prevented from coming into contact with the packing, and heat transfer from the housing to the packing can be prevented. Since it is suppressed, there is little deterioration of the packing due to corrosion or temperature rise. For this reason, the replacement frequency of the packing is small and maintenance is easy.
[0014]
According to the reflow furnace according to claim 2, since the temperature rise of the packing can be further suppressed, the deterioration of the packing is further suppressed.
[0015]
According to the reflow furnace according to the third aspect, since the temperature rise of the packing due to heat transfer from the housing to the packing is suppressed, it is further effective in suppressing the deterioration of the packing.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a reflow furnace according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper housing 11 Side wall 12 Heat insulating material 13 Outer side plate 13a Ventilation hole 1a Overlapping surface 1b Gutter part 2 Lower housing 21 Side wall 22 Heat insulating material 2a Overlapping surface 2b Gutter part 23 Outer plate 23a Ventilation hole 3 Packing

Claims (2)

In the reflow furnace in which the upper housing having the heat insulating material is detachably overlapped on the upper portion of the lower housing having the heat insulating material, and the air inside the furnace is prevented from leaking from the overlapping surface of these housings by packing,
An outwardly extending lower collar portion formed outside the overlapping surface of the lower housing and outside the heat insulating material, and an outside formed outside the overlapping surface of the upper housing and outside the heat insulating material. by an upper flange portion extending towards said annular holding portion which opens outwardly of the furnace body outside of the heat insulating material is constituted, it was superposed surface and adhered overlapping surfaces and each other of the lower housing of the upper housing together is, the packing is held between the annular holding portion in a state in which a gap between its outer surface a whole or one prior Symbol insulation material is exposed to the outside, that between the two housings is sealed Reflow furnace characterized by. The reflow furnace according to claim 1, wherein the outer plate of each housing has a plurality of ventilation holes, and a gap is provided between the outer plate and the heat insulating material.

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