Conveyance heating device

Abstract

To provide a conveyance heating device capable of reducing power consumption.SOLUTION: A conveyance heating device includes a heating device which has a furnace body and is configured to blow hot air to an object to be heated in the furnace body, and a conveyance conveyor for conveying the object to be heated in the furnace body, wherein the furnace body has a furnace wall, a heat insulation material provided inside the furnace wall, a furnace inner wall coating the inside surface of the heat insulation material, and a housing which is provided outside the furnace wall and holds the furnace wall, and heat capacities of the furnace wall and the furnace inner wall are different from one another.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a transport and heating device that is applied to, for example, a reflow device. [Background technology]

[0002] A conveying and heating device such as a reflow device includes a furnace body to which a heated object such as a printed circuit board is supplied. Some furnace bodies include a furnace wall and a housing that is provided on the outside of the furnace wall and supplements the rigidity of the furnace wall. Since the furnace wall and the housing are made of a metal such as stainless steel, when the inside of the furnace body is heated, the furnace wall is heated first by thermal convection and thermal conduction, and then the heat is dissipated to the outside. In order to reduce such heat dissipation and to save power, it has been proposed to cover the reflow furnace with a heat insulating material.

[0003] For example, Patent Document 1 discloses a technology that improves insulation without increasing the thickness of the insulation layer by sequentially arranging an insulation layer, a heat-resistant resin sheet, an insulation layer, and a resin sheet adjacent to the outside of the inner wall (steel plate) of the heating chamber to form the peripheral wall of the furnace. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-170070 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the furnace walls and the housing have a large heat capacity, a large amount of heat is absorbed by the furnace walls and the housing before it reaches the insulation material, and the insulation material is not used effectively. In addition, considering the rigidity of the furnace body, the furnace walls and the housing need to be thick to a certain extent, so it is difficult to reduce the heat capacity of the furnace walls and the housing. Therefore, even if the furnace body is covered with insulation material, the reduction in the power consumption of the heater for heating the inside of the furnace is limited to a certain extent.

[0006] An object of the present invention is to provide a transporting and heating device capable of reducing power consumption. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: The heating device has a furnace body and is configured to be able to blow hot air onto the object to be heated inside the furnace body, and a transport conveyor that transports the object to be heated inside the furnace body. The furnace body has a furnace wall, a heat insulating material provided on the inside of the furnace wall, an inner furnace wall covering the inner surface of the heat insulating material, and a housing provided on the outside of the furnace wall and holding the furnace wall, The heat capacity of the furnace wall and the inner wall is different. It is a transport and heating device. Effect of the Invention

[0008] According to at least one embodiment, the power consumption of the conveying and heating device can be reduced. Note that the effects described herein are not necessarily limited, and any of the effects described in this specification may be used. In addition, the contents of the present invention should not be interpreted as being limited to the effects exemplified in the following description. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an outline of a reflow apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a graph showing an example of a temperature profile during reflow. [Diagram 3] FIG. 3 is a cross-sectional view showing the configuration of the furnace body. [Figure 4] FIG. 4 is a perspective view showing the configuration of the housing. [Diagram 5] FIG. 5 is a cross-sectional view showing the configuration of the furnace body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in the following order. <1. One embodiment> <2. Examples> <3. Modifications> It should be noted that the embodiment described below is a preferred specific example of the present invention, and various technically preferable limitations are applied thereto. However, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited thereto.

[0011] <1. One embodiment> Fig. 1 shows a schematic configuration of a reflow apparatus 101 according to an embodiment of the present invention. The reflow apparatus 101 includes a reflow furnace 102 as a heating device, a conveyor chain 103 as a conveying means for conveying an object to be heated, for example, a printed circuit board (hereinafter referred to as a "work") W having surface mount electronic components and solder mounted on both sides of the printed wiring board, through the reflow furnace 102, rotors (idlers, sprockets, etc.) 104a, 104b, 104c, 104d that define the movement path of the conveyor chain 103, and an outer plate 105. Note that Fig. 1 shows only one conveyor chain 103 of two parallel conveyor chains.

[0012] The reflow furnace 102 heats the workpiece W from above and below, and then cools it after heating. The conveyor chain 103 is one of two conveyor chains arranged parallel to the conveying direction. For example, a roller chain is used as the conveyor chain 103. The outer plate 105 is a case that covers the entire structure.

[0013] The workpiece W is carried into the reflow furnace 102 from the carry-in entrance 106, then transported by the transport chain 103 in the direction of the arrow (from left to right in FIG. 1) at a predetermined speed, and finally removed from the carry-out exit 107. Although not shown, a workpiece carry-in device for carrying in the workpiece W is provided in front of the carry-in entrance 106, and a workpiece unloading device for sending the workpiece W to the outside is disposed in the rear of the unloading exit 107.

[0014] Along the transport path from the inlet 106 to the outlet 107, the reflow furnace 102 is divided into, for example, nine zones Z1 to Z9, and these zones Z1 to Z9 are arranged in-line. The seven zones Z1 to Z7 from the inlet 106 side are heating zones, and the two zones Z8 and Z9 on the outlet 107 side are cooling zones. Forced cooling units (not shown) are provided in association with the zones Z8 and Z9. Note that the number of zones is merely an example, and other numbers of zones may be provided.

[0015] The reflow furnace 102 has a furnace body 10. A heating chamber 102a is defined in each of the zones Z1 to Z7 of the furnace body 10. A cooling chamber 102b is defined in each of the zones Z8 and Z9 of the furnace body 10.

[0016] The heating chambers 102a of the above-mentioned multiple zones Z1 to Z7 and the cooling chambers 102b of zones Z8 and Z9 control the temperature of the workpiece W according to a temperature profile during reflow. An example of a temperature profile is outlined in Fig. 2. The horizontal axis represents time, and the vertical axis represents the surface temperature of the workpiece W. The first section is a temperature rise section R1 where the temperature rises due to heating, the next section is a preheat section R2 where the temperature is almost constant, the next section is a reflow (main heating) section R3, and the last section is a cooling section R4.

[0017] The temperature rise section R1 is a period in which the workpiece W is heated from room temperature to the preheat section R2 (for example, 150°C to 170°C). The preheat section R2 is a period in which, for example, isothermal heating is performed to activate the flux, remove the oxide film on the surface of the electrodes and solder powder, and eliminate uneven heating of the workpiece W. The reflow section R3 (for example, peak temperature of 220°C to 240°C) is a period in which the solder melts and the joining is completed. In the reflow section R3, it is necessary to raise the temperature to a temperature exceeding the melting temperature of the solder. Even if the preheat section R2 has been passed, there is unevenness in the temperature rise, so that the reflow section R3 requires heating to a temperature exceeding the melting temperature of the solder. The final cooling section R4 is a period in which the workpiece W is rapidly cooled and a solder composition is formed. In the case of lead-free solder, the temperature in the reflow section R3 is higher (for example, 240°C to 260°C).

[0018] 2, curve 1 shows an example of a temperature profile for lead-free solder. An example of a temperature profile for Sn-Pb eutectic solder is shown by curve 2. Since the melting point of lead-free solder is higher than that of eutectic solder, the set temperatures in preheat section R2 and reflow section R3 are higher than those for eutectic solder.

[0019] In the reflow apparatus 101 shown in Fig. 1, the temperature control of the heating section R1 in Fig. 2 is mainly handled by zones Z1 and Z2. The temperature control of the preheating section R2 is mainly handled by zones Z3, Z4, and Z5. The temperature control of the reflow section R3 is handled by zones Z6 and Z7. The temperature control of the cooling section R4 is handled by zones Z8 and Z9.

[0020] During reflow, the furnace body 10 is filled with atmospheric gas, such as nitrogen (N2) gas. In the furnace body 10, hot air (heated atmospheric gas) is blown onto the workpiece W to heat the workpiece W. Infrared rays may be irradiated together with the hot air.

[0021] The structure of the furnace body 10 will be described with reference to Fig. 3. The furnace body 10 has an upper furnace body 11A and a lower furnace body 11B. The upper furnace body 11A and the lower furnace body 11B have the same layer structure, and have a furnace wall 111, a heat insulating material 112, a furnace inner wall 113, and a housing 114.

[0022] The furnace wall 111 is provided on the outside of the heat insulating material 112. The furnace wall 111 has a box shape and is composed of a plate-shaped metal layer. The metal layer contains, for example, iron or an iron alloy. Examples of the iron alloy include stainless steel (SUS) and carbon steel. The thickness t1 of the furnace wall 111 is, for example, 1.0 mm or more and 2.0 mm or less.

[0023] The heat insulating material 112 is provided on the inside of the furnace wall 111. The heat insulating material 112 can suppress heat transfer from the furnace inner wall 113 to the furnace wall 111. The heat insulating material 112 has a plate or blanket shape and is composed of one heat insulating layer or multiple heat insulating layers. The heat insulating material 112 includes, for example, inorganic fibers. The inorganic fibers include, for example, artificial mineral fibers such as artificial amorphous fibers. Specifically, the inorganic fibers include at least one type selected from the group consisting of glass wool and alkaline earth silicate wool (AES). A specific example of the glass wool is Calhon L manufactured by Nikko Kasei Co., Ltd. A specific example of the alkaline earth silicate wool is Fineflex BIO (registered trademark) blanket manufactured by Nichias Corporation. The thickness t3 of the heat insulating material 112 is, for example, 25 mm or more and 100 mm or less.

[0024] The furnace inner wall 113 covers the inner side of the insulation material 112. The furnace inner wall 113 is composed of a thin plate-like or foil-like metal layer, and is provided on the inner side of the insulation material 112. However, the form of the metal layer is not limited to a thin plate-like or foil-like form, and the metal layer may be directly formed on the inner side of the insulation material 112. In other words, the furnace inner wall 113 may be composed of a thin film-like metal layer. The metal layer constituting the furnace inner wall 113 may cover the area other than the inner side of the insulation material 112, and may cover the entire surface of the insulation material 112, for example. The metal layer includes, for example, iron or an iron alloy, specifically, for example, stainless steel.

[0025] The heat capacity of the furnace inner wall 113 is different from that of the furnace wall 111. The heat capacity of the furnace inner wall 113 is preferably smaller than that of the furnace wall 111. This suppresses heat absorption by the furnace inner wall 113 and effectively utilizes the function of the heat insulating material 112. Therefore, the power consumption of the reflow apparatus 101 can be reduced.

[0026] The thickness t2 of the furnace inner wall 113 may be different from the thickness t1 of the furnace wall 111. From the viewpoint of reducing the heat capacity of the furnace inner wall 113, the thickness t2 of the furnace inner wall 113 is preferably thinner than the thickness t1 of the furnace wall 111. From the viewpoint of reducing the heat capacity of the furnace inner wall 113, the upper limit value of the thickness t2 of the furnace inner wall 113 is preferably 0.5 mm or less. From the viewpoint of ensuring the strength of the furnace inner wall 113, the lower limit value of the thickness t2 of the furnace inner wall 113 is preferably 0.1 mm or more.

[0027] The metal constituting the furnace inner wall 113 may be the same as the metal constituting the furnace wall 111, or may be different from the metal constituting the furnace wall 111. When the metal constituting the furnace inner wall 113 and the furnace wall 111 is the same, it is preferable that the thickness t2 of the furnace inner wall 113 is thinner than the thickness t1 of the furnace wall 111 from the viewpoint of reducing the heat capacity of the furnace inner wall 113. The specific heat of the material constituting the furnace inner wall 113 may be different from the specific heat of the material constituting the furnace wall 111. It is preferable that the specific heat of the material constituting the furnace inner wall 113 is smaller than the specific heat of the material constituting the furnace wall 111 from the viewpoint of reducing the heat capacity of the furnace inner wall 113.

[0028] FIG. 4 is a perspective view showing the configuration of the housing 114. The housing 114 is provided on the outside of the furnace wall 111. The housing 114 is fixed to the furnace wall 111 by welding, for example. The housing 114 is for holding the furnace wall 111 and supplementing the rigidity of the furnace wall 111. Here, the housing 114 includes not only a box-shaped one that houses the furnace wall 111, but also a frame-shaped one. In one embodiment, an example will be described in which the housing 114 is a frame made of a rectangular columnar pipe material. The pipe material is made of a metal plate. The metal plate includes iron or an iron alloy. Examples of the iron alloy include stainless steel (SUS) or carbon steel. The thickness t4 of the metal plate is, for example, 1.5 mm or more and 2.0 mm or less.

[0029] The upper furnace body 11A is provided with a blower 12A and a heating source 13A. The lower furnace body 11B is provided with a blower 12B and a heating source 13B, as with the upper furnace body 11A. The blower 12A is held at the top of the upper furnace body 11A so as to face the transport path of the workpiece W. The blower 12A blows hot air onto the workpiece W from above the workpiece W via the heating source 13A. The blower 12B is held at the bottom of the lower furnace body 11B so as to face the transport path of the workpiece W. The blower 12B blows hot air onto the workpiece W from below the workpiece W via the heating source 13B.

[0030] The blowers 12A and 12B each have a motor 121 and a rotary blade 122. For example, a centrifugal fan such as a turbo fan or a sirocco fan, or an axial blower may be used as the blowers 12A and 12B. The heating source 13A is provided between the blower 12A and the conveying path of the workpiece W. The heating source 13A heats the air sent out by the blower 12A to generate hot air. The heating source 13B is provided between the blower 12B and the conveying path of the workpiece W. The heating source 13B heats the air sent out by the blower 12B to generate hot air. The heating sources 13A and 13B are, for example, electric heaters. The hot air generated in the upper furnace body 11A by the blower 12A and the heating source 13A circulates in the upper furnace body 11A. Hot air generated in the lower furnace body 11B by the blower 12B and the heat source 13B circulates within the lower furnace body 11B.

[0031] According to the embodiment of the present invention described above, the furnace body 10 has a furnace wall 111, a heat insulating material 112 provided inside the furnace wall 111, and a furnace inner wall 113 covering the inner side of the heat insulating material 112, and the heat capacity of the furnace inner wall 113 is smaller than that of the furnace wall 111. This makes it possible to suppress heat absorption by the furnace inner wall 113, and to effectively utilize the function of the heat insulating material 112. Therefore, it is possible to reduce power consumption compared to a conventional reflow apparatus in which the furnace wall 111 is provided inside the heat insulating material 112. In addition, it is possible to shorten the heating time required for the heating chamber 102a to reach the set temperature. Furthermore, it is possible to shorten the time required for changing the type of product.

[0032] <2. Examples> The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0033] [Example 1] The power consumption of a small reflow soldering machine having two heating chambers and one cooling chamber was measured. The furnace body of the reflow soldering machine had the configuration described in the embodiment (see FIG. 3), and in order to clarify the effect of the present invention, the outside of the furnace body was covered with a heat insulating material as in Comparative Example 1. In the following description, the heat insulating material constituting the furnace body (the heat insulating material arranged on the inside of the furnace wall) is sometimes referred to as the inner heat insulating material, and the heat insulating material arranged on the outside of the furnace body is sometimes referred to as the outer heat insulating material. The inner wall of the furnace was formed of a thin plate of SUS304. The materials and thicknesses of the furnace inner wall, inner insulation, furnace wall, casing and outer insulation were as follows: Furnace inner wall: SUS304, thickness 0.3 mm Inner insulation: Nikko Kasei Karuhon L, 25mm thick Furnace wall: SUS304, thickness 1.5mm Housing: SUS304, thickness (thickness of the metal plate that constitutes the rectangular pipe material) 1.5 mm Outer insulation: Glass wool (with aluminum foil), 50mm thick

[0034] [Comparative Example 1] As in Example 1, a small reflow soldering machine having two heating chambers and one cooling chamber was used to measure the power consumption of the reflow soldering machine. The furnace body of the reflow soldering machine had a furnace wall and a housing provided on the outside of the furnace wall, and the outside of the furnace body was covered with an external heat insulating material. The materials and thicknesses of the furnace wall, the housing, and the external heat insulating material were the same as those of the furnace wall, the housing, and the external heat insulating material in Example 1, and the volume inside the furnace body was the same as that in Example 1.

[0035] From the measurement results of the power consumption in Example 1 and Comparative Example 1, it was found that the power consumption of the reflow apparatus in Example 1 was reduced by about 10% compared to the power consumption of the reflow apparatus in Comparative Example 1.

[0036] <3. Modifications> Although the embodiments of the present invention have been specifically described above, they are not limited to the above-mentioned embodiments, and various modifications based on the technical idea of ​​the present invention are possible. For example, the configurations, methods, steps, shapes, materials, and values, etc., given in the above-mentioned embodiments are merely examples, and different configurations, methods, steps, shapes, materials, and values, etc., may be used as necessary. In addition, the configurations, methods, steps, shapes, materials, and values, etc., of the above-mentioned embodiments can be combined with each other as long as they do not deviate from the gist of the present invention. In addition, the furnace body 10 may further include a heat insulating material on the outside of the housing 114, and the furnace wall 111 may be covered with the heat insulating material. In this case, the power consumption of the reflow device 101 can be further reduced. In addition, an air layer may be present between the heat insulating material 112 and the furnace wall 111. In this case, hot air may circulate through the air layer. The present invention is not limited to printed circuit boards, but can also be applied to the reflow of flexible boards, boards in which a rigid board and a flexible board are bonded together, and rigid-flex boards in which these are combined. In addition, the present invention can be applied to a reflow device with a single heating furnace (one zone).

[0037] In the embodiment, an example in which the furnace wall 111 and the furnace inner wall 113 are both made of metal has been described, but the configurations of the furnace wall 111 and the furnace inner wall 113 are not limited to this example, and the furnace wall 111 and the furnace inner wall 113 may be made of different materials. Specifically, for example, the furnace wall 111 may be made of a metal layer, whereas the furnace inner wall 113 may be made of a nonmetallic layer containing a nonmetallic inorganic material. As the nonmetallic inorganic material, for example, ceramics can be used. As the ceramics, it is preferable to use zirconia (ZrO2) or cordierite (2MgO·2Al2O3·5SiO2) from the viewpoint of reducing the heat capacity of the furnace inner wall 113.

[0038] The non-metallic layer has a thin plate or foil shape. The lower limit of the thickness t2 of the non-metallic layer is preferably 1 mm or more from the viewpoint of ensuring the strength of the furnace inner wall 113, and the upper limit of the thickness t2 of the non-metallic layer is preferably 5 mm or less from the viewpoint of suppressing the weight increase of the furnace body 10.

[0039] 5, the furnace inner wall 113 may be composed of a non-metallic layer 113A such as a ceramic layer and a metallic layer 113B. In this case, the non-metallic layer 113A and the metallic layer 113B are preferably provided in this order from the inside to the outside of the furnace inner wall 113.

[0040] The non-metallic layer 113A may be a thin film such as a ceramic coating layer. 21 The thickness t of the metal layer 113B is, for example, about 30 μm. However, the form of the non-metal layer 113A is not limited to a thin film such as a ceramic coating layer, and may be a thin plate or foil. The metal layer 113B may be the same as the metal layer constituting the furnace inner wall 113 in one embodiment. 22 may be similar to the thickness t2 of the furnace inner wall 113 in one embodiment. [Explanation of symbols]

[0041] 10 furnace body, 11A upper furnace body, 11B lower furnace body, 111 furnace wall, 112 heat insulating material, 113 furnace inner wall, 113A non-metal layer, 113B metal layer, 114 housing, 12A, 12B blower, 121 motor, 122 rotating blade, 13A, 13B heat source, 101 reflow device, 102 reflow - Furnace, 102a... heating chamber, 102b... cooling chamber, 103... conveyor chain, 104a, 104b, 104c, 104d... rotating body, 105... outer plate, 106... entrance, 107... exit, R1... heating section, R2... preheating section, R3... reflow (main heating) section, R4... cooling section, W... work, Z1 to Z9... zones

Claims

1. The heating device has a furnace body and is configured to be able to blow hot air onto the object to be heated in the furnace body, and a conveyor that conveys the object to be heated in the furnace body. The furnace body includes a furnace wall, a heat insulating material provided on the inside of the furnace wall, an inner furnace wall covering the inner surface of the heat insulating material, and a housing provided on the outside of the furnace wall and holding the furnace wall. The furnace wall and the furnace inner wall have different heat capacities Transport heating device.

2. 2. The conveying and heating device according to claim 1, wherein the heat capacity of the furnace inner wall is smaller than the heat capacity of the furnace wall.

3. 3. The conveying and heating device according to claim 1, wherein the furnace wall and the furnace inner wall are made of metal.

4. 4. The conveying and heating device according to claim 3, wherein the furnace wall and the furnace inner wall are made of different metals.

5. The conveying and heating device according to claim 2 , wherein the furnace wall and the furnace inner wall have different thicknesses.

6. 3. The conveying and heating device according to claim 1, wherein the furnace wall and the furnace inner wall are made of different materials.

7. The furnace wall is made of metal, 3. The conveying and heating device according to claim 1, wherein the furnace inner wall is made of a non-metallic inorganic material.

8. The transporting and heating device according to claim 7 , wherein the non-metallic inorganic material includes ceramics.

9. 3. The conveying and heating device according to claim 1, wherein the furnace inner wall includes a ceramic layer and a metal layer in this order from the inside to the outside of the furnace inner wall.

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