JP2006339171A - Reflow soldering apparatus and reflow soldering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent reflection by suppressing a temperature rise of the other face side without using a private cooling means when only one side of a printed wiring board is heated and reflow soldering is performed, to protect an electronic component with a low heat resistant temperature on the printed wiring board from damage and to prevent occurrence of reflow on solder in a part to be soldered, where soldering on the printed wiring board is completed. <P>SOLUTION: A furnace casing is divided into an upper furnace casing 101 and a lower furnace casing 102 and the upper furnace casing 101 and the lower furnace casing 102 are integrally connected through an insulating material. A heat insulation plate 110 which can freely be attached to/detached from a face confronted with the printed wiring board of a heating means on at least one furnace casing-side among a plurality of heating means (106 to 110) which are arranged in the upper furnace casing 101 and the lower furnace casing 102 and can independently be operated is disposed by making it confront with a printed wiring board 100 conveyed inside the furnace casing by a conveyor 105. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reflow soldering apparatus and method for soldering a printed wiring board on which electronic parts are mounted and solder is supplied in advance to a soldered portion thereof.

  There are various reflow soldering methods. In addition to the method of performing reflow soldering on both sides of a printed wiring board at once, reflow soldering on one side and then reflow soldering on the other side There are a method, a method of performing reflow soldering on only one surface, and the like because there are soldered portions only on one surface. These are selected depending on the type of electronic component to be soldered and mounted on the printed wiring board and the mounting structure.

  A general reflow soldering apparatus is configured to be able to perform both-sided reflow soldering of a printed wiring board by providing heating means facing each side of the printed wiring board conveyed in the furnace body. . When reflow soldering is performed only on one surface side of the printed wiring board, the reflow soldering is performed by stopping the heating means on the side where the soldering is not performed.

  As the heating means, combined heating mainly using hot air heating means and auxiliary use of infrared heating means is generally used, and there is a configuration of only hot air heating means, but infrared radiation is also generated from this hot air heating means. There is no configuration of only a complete hot air heating means. For convenience, a case where the heating rate by infrared rays is small is usually called a hot air heating method.

  By the way, when reflow soldering is performed by heating only one surface side of the printed wiring board, the temperature of the unheated surface side, that is, the surface temperature of the printed wiring board or the temperature of the electronic component to be mounted is predetermined. There are cases in which reflow soldering is desired to be limited to below the temperature.

  For example, there is a case where a component that has already been soldered is mounted and it is desired to prevent a decrease in soldering quality due to remelting of the solder, or an electronic component having a low heat-resistant temperature is mounted. Hereinafter, a description will be given with reference to FIG.

  FIG. 4 is a diagram illustrating an example of a printed wiring board that performs reflow soldering. 4A corresponds to a mounting example in which a lead-type electronic component having a low heat-resistant temperature is mounted on the printed wiring board, and FIG. 4B shows that the soldering has already been completed on the printed wiring board. This corresponds to a mounting example in which a certain part is mounted.

  4A and 4B, reference numeral 401 denotes a printed wiring board. A soldered portion is provided on the lower surface of the printed wiring board 401, and cream solder 402 is supplied in advance to the soldered portion.

  In the example of FIG. 4A, a lead type electronic component 403 having a low heat resistance temperature is mounted on the upper surface of the printed wiring board 401.

  In the example of FIG. 4B, the chip-type electronic component 405 that has already been soldered is mounted on the upper surface of the printed wiring board 401.

  When the reflow soldering of the chip type components 404 and 407 of the printed wiring board 401 as shown in FIGS. 4A and 4B is performed, the heat resistance temperature of the lead type electronic component 403 and the soldering are already completed. The temperature of the upper surface of the printed wiring board 401 should not be raised above the temperature at which the solder of the soldered portion 406 of the chip-type electronic component 404 is remelted. Therefore, the operation of the heating means on the upper side of the reflow soldering apparatus is stopped to perform soldering.

  However, in a general reflow soldering apparatus, even if the operation of the heating means on the side where soldering is not performed (the upper side in FIGS. 4A and 4B) is stopped, the upper side of the printed wiring board 401 ( The actual situation is that the temperature of the surface on the side where soldering is not performed and the temperature of the electronic component are not lowered sufficiently. In other words, the solder of the soldered portion 406 that has already been soldered is remelted, or the electronic component 403 having a low heat-resistant temperature is damaged and the performance cannot be maintained.

For this reason, as disclosed in Patent Document 1, a special reflow soldering device is used in which cold air (outside air) is introduced into the furnace so that a predetermined temperature can be maintained on the side where soldering is not performed. ing.
JP-A-4-271192

  However, the technique of Patent Document 1 cannot be applied to a reflow soldering apparatus in which an inert gas such as nitrogen gas is supplied into the furnace body and soldering is performed in an inert gas atmosphere having a low oxygen concentration. .

  That is, maintaining an inert gas atmosphere having a low oxygen concentration in the furnace body is contradictory to cooling by introducing outside air (cold air).

  Further, even in a reflow soldering apparatus that performs reflow soldering in an air atmosphere, there is a problem that it is difficult to adjust the external air supply amount so that a predetermined temperature is reached. If the amount of outside air supply increases, not only will the temperature of the printed wiring board decrease excessively, but the heating temperature of the surface on which reflow soldering will be performed will also decrease, making it difficult to obtain the heating profile required for soldering. is there.

  Furthermore, if each of the general reflow soldering apparatus and the reflow soldering apparatus as disclosed in Patent Document 1 is installed, not only the production cost increases but also the space in the factory cannot be used effectively. There was also a problem.

  The present invention has been made to solve the above problems, and the object of the present invention is to heat only one surface side of the printed wiring board (with the heating means on the other surface side paused). When reflow soldering is performed, the temperature rise on the other surface side is suppressed without using a dedicated cooling means, and electronic components with low heat resistance on the printed wiring board are protected from damage. In order to prevent remelting of the solder of the soldered part where the soldering is completed, the reflection is prevented and the temperature offset in the state where the heating means on the other side is inactive is variable. An object of the present invention is to realize a reflow soldering apparatus capable of performing the above.

  The reflow soldering apparatus according to the present invention is characterized in that the temperature offset can be varied by significantly reducing the thermal energy emitted from other than the operating heating means.

  That is, the furnace body is divided into an upper furnace body and a lower furnace body, and when the upper furnace body and the lower furnace body are integrally connected via a heat insulating material, a carry-in port and a carry-out port are connected to the furnace body. And a means for conveying the printed wiring board is provided across the carry-in port and the carry-out port. The heating means capable of independently operating both the upper furnace and the lower furnace is provided facing the printed wiring board conveyed by the conveying means, and the printed wiring board of the heating means of the furnace on at least one side A heat-insulating plate that can be attached and detached is provided on the surface facing the surface.

  Even if the heating means on one side stops its operation (that is, heating), it is heated by the heating means on the other side or the atmosphere temperature in the furnace rises, so infrared radiation (so-called reflection) due to the temperature is generated. Arise. Therefore, the temperature of the region (surface side) where it is not desired to raise the temperature does not drop that much. However, by dividing the furnace body into upper and lower parts and connecting them through a heat insulating material, heat conduction from one furnace body to the other furnace body is eliminated, and an offset can be given to the furnace body temperature. Further, by covering the heating means whose operation is stopped with a heat insulating plate, it is possible to cut off the heating energy from the operating heating means and reduce the temperature rise to prevent reflection.

  As a result, there is no reflection from the heating means and the furnace body that have stopped operating, and the temperature rise of the other surface can be significantly suppressed while heating one surface of the printed wiring board.

  In addition, the heat insulating plate used in the above configuration is a member having a thermal conductivity of 1.1 W / (mk) or less, and a member having a ratio of radiation having a wavelength of 1 μm or more to radiation at the furnace atmosphere temperature of 30% or less. . That is, it is known that a printed wiring board and electronic components mounted on the printed wiring board easily absorb infrared rays having a wavelength of 1 μm or more, thereby easily raising the temperature.

  Therefore, by using a heat insulating plate that does not cause such reflection in the wavelength band, it is possible to reduce the reflection from the heat insulating plate that causes the temperature increase while suppressing the temperature increase of the heating means during operation stop. .

  Moreover, while the heat conductivity of steel and aluminum is 60-210 W / (mk), by making the heat conductivity of a heat insulation board 1/100 or less, it is to the heating means which has stopped. Heat conduction and radiant heating hardly occur.

  According to the reflow soldering apparatus of the present invention, when reflow soldering is performed by heating only one surface side of the printed wiring board, the temperature rise on the unheated surface side is not performed without using a dedicated cooling means. To prevent electronic reflections, protect electronic components with low heat resistance from damage, and prevent remelting of solder in the soldered parts where soldering has been completed. it can.

  In addition, it is possible to maintain an inert gas atmosphere with a low oxygen concentration, and there is no need to additionally install a dedicated reflow soldering apparatus.

  Therefore, the operating range of the reflow soldering apparatus can be greatly expanded to realize all soldering methods with one reflow soldering apparatus, and the cost required for soldering mounting can be greatly reduced. become able to.

  Thus, in a reflow soldering apparatus capable of performing reflow soldering on both sides of a printed wiring board at the same time, when performing reflow soldering on only one side of the printed wiring board, the printed wiring board is soldered. There is an effect that it is possible to realize a reflow soldering apparatus capable of performing a temperature offset between the surface side to be performed and the surface side to which soldering is not performed.

  The offset variable reflow soldering apparatus of the present invention can be realized in the following form.

<Description of configuration>
FIG. 1 is a longitudinal sectional view for explaining an example of the configuration of a reflow soldering apparatus showing an embodiment of the present invention.

  2 is a cross-sectional view showing an example of the cross-sectional configuration of the reflow soldering apparatus shown in FIG. 1, and the same components as those in FIG. 1 are denoted by the same reference numerals. 2 (a) corresponds to the cross-sectional view of the reflow soldering apparatus shown in FIG. 1, and FIG. 2 (b) is an enlarged view of the cross-section of the conveyor 105 shown in FIG. 2 (a). Corresponding to

  As shown in FIG. 1, the reflow soldering apparatus of this embodiment is an example of a 6-zone configuration, 1 zone for the temperature raising process, 2 zones for the soaking process, 2 zones for the reflow process, and 1 zone for the cooling process. Is provided. Note that the number of zones is an arbitrarily selected design item.

  As described above, the furnace body that holds the heating atmosphere and the cooling atmosphere is divided into the upper furnace body 101 and the lower furnace body 102, and as shown in FIG. 2A, a heat insulating material (for example, silicon (Rubber, Teflon (registered trademark) material, etc.) 201 are integrally formed.

  The joining positions of the upper furnace body 101 and the lower furnace body 102 by the heat insulating material 201 are the heating surface of the printed wiring board 100 (the lower surface in FIG. 2A) and the surface where the heating is not performed (FIG. 2A). Is the position of the conveyor 105 that is the interface position with the upper surface. Further, the heating furnace is provided with a carry-in port 103 for carrying in the printed wiring board and a carry-out port 104 for carrying out, and a conveyor (chain conveyor) 105 extends the printed wiring board 100 from the carry-in port 103 to the carry-out port 104. It is configured to carry.

  The conveyor 105 is attached to the reflow soldering apparatus main body by a conveyor frame (not shown), and has a chain guide 202 and a conveyor chain 203 as shown in FIG. Further, the transport chain 203 is provided with pins 204 and a guide plate 205. The transport chain 203 travels along a chain guide 202 that is a travel path, thereby transporting the printed wiring board 100 held by the pins 204 and the guide plate 205. Note that this type of conveyor is disclosed in Japanese Patent Laid-Open No. 10-163622.

  As described above, the furnace body is divided into the upper furnace body 101 and the lower furnace body 102 with the conveyance conveyor 105 interposed therebetween, and is thermally insulated by the heat insulating material 201. The heat can be dissipated and the temperature can be greatly reduced.

  In the present embodiment, as an example of the heat insulating material 201, a heat insulating material made of silicon rubber or Teflon (registered trademark) material is cited, but the heat insulation between the upper furnace body 101 and the lower furnace body 102 as described above. Needless to say, any material may be used as long as it is for the purpose.

  On the other hand, the zones of the temperature raising process, the soaking process, and the reflow process have the same configuration, and heating means (106 to 110) are provided in both the upper furnace body 101 and the lower furnace pair 102, respectively. Yes. The structure of this heating means is a hot air circulation type, and the atmosphere heated by the heater 106 is circulated by a fan 108 driven to rotate by a motor 107, and hot air blown from a large number of through holes of the hot air blowing plate 109 is applied to the printed wiring board. It is the structure which sprays and heats. The hot air blowing plate 109 is made of a material such as aluminum, for example.

  The hot air thus blown returns to the heater 106 side through the reflux path 110. In addition, infrared rays are radiated from the hot air blowing plate 109 heated to the hot air temperature, and the printed wiring board 100 is heated by infrared rays as a function of a temperature difference from the printed wiring board 100. Therefore, heating mainly using hot air heating and supplementary infrared heating is performed.

  With such a configuration, the reflow soldering apparatus of the present embodiment performs soldering of the printed wiring board 100 on which electronic components are mounted and cream solder is supplied in advance to the soldered portion.

  The heating means for the upper furnace body 101 and the heating means for the lower furnace body 102 can be operated independently, and only one side of the printed wiring board conveyed by the conveyor 105 can be reflow soldered.

  In addition, as shown to Fig.2 (a), the conveyance conveyor 105 does not interrupt | block the upper furnace body 101 and the lower furnace body 102. FIG. Therefore, in each zone of the temperature raising process, the soaking process, and the reflow process, even if the heating means of one furnace body (for example, the upper furnace body 101) is stopped, the other furnace body (that is, the lower side path). When the heating means of the body 102) is actuated, the hot air blown from the hot air blowing plate 109 of the lower path body 102 or the temperature inside the furnace rises, whereby the hot air blowing plate 109 of the upper furnace body 101 is heated. As a result, infrared radiation (so-called reflection) is generated. Thereby, the situation where the side (namely, upper side) which stopped the heating means of the printed wiring board 100 conveyed by the conveyance conveyor 105 will also generate | occur | produce will occur.

  Therefore, in the present embodiment, the hot air blowing of the hot air blowing plate 109 (the hot air blowing plate 109 of both the upper furnace body 101 and the lower path body 102) provided in each zone of the temperature raising process, the soaking process, and the reflow process. The heat insulating plate 111 can be detachably provided on the surface (that is, the surface facing the printed wiring board 100 conveyed by the conveyor 105) so as to cover the hot air blowing surface.

  In the example of FIGS. 1 and 2, the heat insulating plate 111 is attached to the hot air blowing plate 109 on the upper side of the reflow process using a fixture 112. That is, by this, the heating means on one side (the heating means that is stopped) is covered with the heat insulating plate 111, and the temperature of the printed wiring board 100 due to the reflection from the furnace body on the heating side as described above. It is possible to prevent the rise.

  In the example of FIGS. 1 and 2, the heat insulating plate 111 is attached to the upper hot air blowing plate 109 in the reflow process using the fixture 112, but the heat insulating plate 111 is fixed to the lower hot air blowing plate 109. 112 may be used for attachment.

  FIG. 3 is a diagram showing an example of a configuration for attaching and detaching the heat insulating plate 111 shown in FIG. 1 to the hot air blowing plate 109, and corresponds to the drawing by enlarging the longitudinal sectional view shown in FIG. 1 and 2 are denoted by the same reference numerals.

  In other words, a hanging tool (consisting of a spring 302 and a fixing tool 112) with a spring 302 interposed is hung on a hanging tool 301 provided on the heat insulating plate 111, and the fixing tool 112 is tightened in the upward direction of the arrow B to be detachably fixed. It is the structure to do.

  Moreover, when removing the heat insulation board 111, the hanging tool can be removed from the hanger provided in the heat insulation board 111 by loosening the fixture 112 in the arrow B downward direction.

  The method for attaching and detaching the heat insulating plate 111 to the hot air blowing plate 109 is not limited to the method shown in FIG. 3, and any method can be used as long as the heat insulating plate 111 can be attached to and detached from the hot air blowing plate 109. There may be. For example, a method may be used in which a rail is provided on the hot air blowing plate 109 and the heat insulating plate 111 is inserted and attached to the rail.

  Moreover, as a member which can be used for the heat insulation board 111, a white-type gypsum board etc. are suitable, for example. This type of gypsum board has many members with a thermal conductivity of 0.9 W / (mk) or less, and is less than 1/100 of the thermal conductivity of steel or aluminum (60 to 210 W / (mk)). It is possible to suppress the temperature rise of the member used for the above very well. In addition, this material hardly emits infrared light having a wavelength of 1 μm or more even when in contact with the atmosphere in the furnace atmosphere temperature (about 200 ° C. to 300 ° C.), and the radiation ratio is about 30% or less of the total radiation. is there.

  In other words, if the proportion of infrared radiation with a wavelength of 1 μm or more is 30% or less, coupled with the fact that it is a white heat insulating material and has less infrared radiation at an ambient temperature of about 200 ° C. to 300 ° C., the printed wiring board is reflected by reflection. There is almost no heating and there is no need to substantially consider the effect.

  Note that the member that can be used for the heat insulating plate 111 is not limited to the white gypsum board, and is a member having a thermal conductivity of 1.1 W / (mk) or less and having a wavelength of 1 μm or more for radiation at the furnace atmosphere temperature. Other members may be used as long as the ratio of radiation is 30% or less.

  Hereinafter, the cooling process of the reflow process will be described with reference to FIG.

  The cooling process provided after the reflow process is configured to blow cold air circulated by a blower onto the printed wiring board 100.

  That is, as shown in FIG. 1, cold air is blown out from a large number of through holes 114 of the blowing plate provided in the blowing chamber 113 and blown to the printed wiring board 100. The atmosphere used for this cooling is sucked in the suction chamber 115, cooled by the heat exchange fins 116, and then returned to the blower 117.

  In addition, the heat exchange fin 116 is a structure which exhausts heat using a heat pipe. A tank 118 provided below the suction chamber 115 is a means for collecting the liquefied flux fumes.

<Description of soldering mode>
Hereinafter, with reference to FIG. 4 shown in the section of the background art, a soldered mounting example of a printed wiring board that performs reflow soldering using the offset variable reflow soldering apparatus shown in FIGS. explain. That is, the case where the printed wiring board 100 shown in FIGS. 1 to 3 is the printed wiring board 401 shown in FIGS. 4A and 4B will be described as an example.

  As described above, both FIG. 4 (a) and FIG. 4 (b) have a soldered portion on the lower surface of the printed wiring board 401, and cream solder 402 is supplied in advance to the soldered portion. It is. In the example of FIG. 4A, a lead-type electronic component 403 having a low heat-resistant temperature is mounted on the upper surface of the printed wiring board 401. In the example of FIG. 4B, the upper side of the printed wiring board 401 is mounted. A chip-type electronic component 405 that has already been soldered is mounted on this surface.

  When reflow soldering of the printed wiring board 401 as shown in FIGS. 4A and 4B is performed, the heat resistance temperature of the lead-type electronic component 403 or chip-type electronic that has already been soldered. The temperature of the upper surface of the printed wiring board 401 should not be raised above the temperature at which the solder of the soldered portion 406 of the component 405 is remelted. Therefore, the operation of the heating means on the upper side of the reflow soldering apparatus is stopped.

  And in the reflow process heated to the highest temperature, the heat insulation board 111 is provided in the heating means provided in the upper side. Of course, the heat insulating plate 111 may be provided in the upper heating means in each zone of the temperature raising step and the soaking step (may be mounted).

  The heating profile of the lower surface of the printed wiring board 401 may be a known heating profile. For example, the temperature is raised to about 150 ° C. in the temperature raising step, and the temperature of 150 ° C. to 170 ° C. is maintained in the soaking step. And in a reflow process, it heats to about 220 degreeC (this temperature changes with kinds of cream solder), and performs reflow soldering.

  When reflow soldering is performed only on the lower surface of the printed wiring board 401 as shown in FIG. 4B, the solder of the soldered portion 406 is remelted in the temperature raising step or the soaking step. Therefore, it is not necessary to provide (attach) the heat insulating plate 111 to the upper heating means.

  However, when performing reflow soldering only on the lower surface of the printed wiring board as shown in FIG. 4A, the temperature raising process or leveling is performed so that the thermal stress applied to the lead type electronic component 403 is reduced. A heat insulating plate 111 may be provided (attached) to the heating means in the heat process.

  Thus, by varying the temperature offset of the reflow soldering apparatus, the temperature of the upper furnace body 101 is lowered, and the blowing plate 109 of the upper furnace body 101 and thus the temperature of the heating means does not increase. .

  In addition, there is almost no infrared radiation from the heat insulating plate 111, and in particular, a white gypsum board hardly emits infrared light having a wavelength of 1 μm or more, and its ratio is 30% or less of the total radiation. The temperature of this surface does not rise to a temperature at which the quality of the lead-type electronic component 403 having a low heat-resistant temperature is impaired or to the remelting temperature of the solder of the soldered portion 406.

  Hereinafter, the temperature characteristics of the upper surface / lower surface of the printed wiring board when the reflow soldering of the printed wiring board is performed by the above-described soldering method using the reflow soldering apparatus having the above-described configuration. Show.

  First, in the reflow soldering apparatus configured as shown in FIGS. 1 to 3, the heat insulating plate 111 is provided (attached) to the heating means of the upper furnace body 101 in the reflow process zone to provide an offset, A case where reflow soldering is performed on the lower surface of the printed wiring board will be described as an example.

  In this case, when a tin-zinc-bismuth solder was used as the solder to be used, the temperature of the lower surface of the printed wiring board in the reflow process was about 220 ° C. On the other hand, the temperature of the upper surface of the printed wiring board was 185 ° C. or lower and was maintained at a temperature significantly lower than the melting point of the solder, so that the solder at the soldered portion did not remelt.

  Next, in the above reflow soldering apparatus, a heat insulating plate 111 is provided (attached) to the heating means of the upper furnace body 101 in all the process zones except the cooling step to provide an offset, and the lower side of the printed wiring board. The case where reflow soldering of the surface of is performed is shown.

  In this case, the temperature of the upper surface of the printed wiring board under the same heating conditions as in the above case was about 175 ° C., and it was possible to eliminate the damage given to the lead type electronic component having a low heat resistance temperature.

  As described above, the reflow soldering apparatus according to the present invention is characterized in that the temperature offset can be varied by greatly reducing the thermal energy emitted from other than the heating means.

  That is, in the reflow soldering apparatus of the present invention, the furnace body is divided into the upper furnace body 101 and the lower furnace body 102, and the upper furnace body 101 and the lower furnace body 102 are integrally connected via the heat insulating material 201. In addition, a carry-in port 103 and a carry-out port 104 are provided in the furnace body, and a conveyer 105 for carrying the printed wiring board 100 over the carry-in port 103 and the carry-out port 104 is provided. And a heating means (106-110) is provided facing the printed wiring board 100 conveyed by the said conveyance conveyor 105, and the heat insulation board 111 is detachable in the surface which faces the printed wiring board 100 of this heating means. It is configured to be provided.

  Even if the heating means (for example, the heating means for the upper furnace body 101) stops its operation (that is, heating), it is heated by another heating means (the heating means for the lower furnace body 102), or the temperature inside the furnace is increased. Since the temperature rises, infrared radiation (so-called reflection) due to the temperature is generated. Therefore, the temperature of the region (surface side) where it is not desired to raise the temperature does not drop that much.

  However, as in the present invention, the furnace bodies are divided into upper and lower parts and joined together via the heat insulating material 201, thereby eliminating heat conduction from one furnace body to the other furnace body, and offsetting to both furnace body temperatures. Will be able to give.

  Moreover, by covering the heating means whose operation is stopped with the heat insulating plate 111, the heating energy from the operating heating means can be cut off, and the temperature rise can be reduced.

  As a result, there is no reflection from the heating means or the furnace body that has stopped operating, and the temperature rise of the other surface can be significantly suppressed while heating one surface of the printed wiring board.

  Further, the heat insulating plate 111 used in the above configuration is a member having a thermal conductivity of 1.1 W / (mk) or less, and a component in which radiation having a wavelength of 1 μm or more is included in radiation in the furnace atmosphere temperature is 30% or less. To do. It is known that a printed wiring board and electronic components mounted on the printed wiring board easily absorb infrared rays having a wavelength of 1 μm or more and thereby easily rise in temperature. Therefore, by using a heat insulating plate that does not cause such reflection in the wavelength band, it is possible to reduce the reflection from the heat insulating plate that causes the temperature increase while suppressing the temperature increase of the heating means during operation stop. .

  In addition, while the thermal conductivity of steel and aluminum is 60 to 210 W / (mk), the heat to the heating means is stopped by making the thermal conductivity of the heat insulating plate 1/100 or less. Little conduction or radiant heating occurs.

  Therefore, according to the reflow soldering apparatus with variable offset according to the present invention, when reflow soldering is performed by heating only one surface side of the printed wiring board (pausing the heating means on the other surface side), Without using a dedicated cooling means, the temperature rise on the other surface side is suppressed and reflection is prevented (that is, the temperature offset in the state where the heating means on the other surface side is inactive can be varied). It is possible to protect an electronic component having a low heat-resistant temperature from damage, and to prevent remelting of the solder of the soldered portion where the soldering has been completed.

  In addition, it is possible to maintain an inert gas atmosphere with a low oxygen concentration, and there is no need to additionally install a dedicated reflow soldering apparatus. In other words, the operating range of the reflow soldering device can be greatly expanded so that all soldering methods can be realized with a single reflow soldering device, and the cost required for soldering mounting can be greatly reduced. Will be able to.

  In recent years, electronic devices have been required to be miniaturized, and all functions of electronic devices have been mounted on a single printed wiring board. For this reason, electronic circuits and electronic components having different functions have been mounted on each surface of the printed wiring board.

  As a result, the types of electronic components mounted on each side of the printed wiring board have become significantly different. For this reason, when performing reflow soldering on a printed wiring board, reflow soldering is performed on both sides at once. Rather, it has become more often done one side at a time. For this reason, when performing the second reflow soldering, it has been required to prevent re-melting of the solder of the soldered portion that has already been soldered.

  The present invention is a technology that supports the progress of solder mounting technology that can be used for soldering such printed wiring boards.

It is a longitudinal section explaining an example of composition of a reflow soldering device showing one embodiment of the present invention. It is a cross-sectional view which shows an example of the cross-sectional structure of the reflow soldering apparatus shown in FIG. It is the figure which showed an example of the attachment or detachment structure to the hot air blowing board of the heat insulation board shown in FIG. It is a figure explaining an example of the printed wiring board which performs reflow soldering.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Printed wiring board 101 Upper furnace body 102 Lower furnace body 103 Carry-in entrance 104 Carry-out exit 105 Conveyor 106 Heater 107 Motor 108 Fan 109 Hot-air blowing board 110 Return path 111 Heat insulation board 112 Fixing tool 201 Heat insulation material

Claims (5)

A furnace body configured to be divided into an upper furnace body and a lower furnace body, and the upper furnace body and the lower furnace body are integrally connected via a heat insulating material,
Conveying means for conveying the printed wiring board over the entrance and exit of the furnace body;
A plurality of heating means that can be independently operated and are provided in each of the upper furnace body and the lower furnace body facing the printed wiring board conveyed by the conveying means,
A heat insulating plate detachably attached to the surface facing the printed wiring board of at least one of the heating means provided in the upper furnace body and the heating means provided in the lower furnace body;
A reflow soldering apparatus comprising:   The heat insulating plate is a member having a thermal conductivity of 1.1 W / (mk) or less, and is configured by a member having a ratio of radiation having a wavelength of 1 μm or more included in radiation in the furnace atmosphere temperature of 30% or less. The reflow soldering apparatus according to claim 1.   When the heating means provided in the upper furnace body or the heating means provided in the lower furnace body is stopped and reflow soldering is performed only on one surface of the printed wiring board, the heating means that is stopped The reflow soldering apparatus according to claim 1, wherein the reflow soldering is performed by attaching the heat insulating plate to the reflow soldering. A furnace body configured to be divided into an upper furnace body and a lower furnace body, and the upper furnace body and the lower furnace body are integrally connected via a heat insulating material, and printing is performed across the entrance and exit of the furnace body Reflow solder having conveying means for conveying a wiring board, and a plurality of independently operable heating means provided in each of the upper furnace body and the lower furnace body facing the printed wiring board conveyed by the conveying means In the reflow soldering method of the attaching device,
When the heating means provided in the upper furnace body or the heating means provided in the lower furnace body is stopped and reflow soldering is performed only on one surface of the printed wiring board, the heating means that is stopped A reflow soldering method for a reflow soldering apparatus, wherein the reflow soldering is performed by mounting a heat insulating plate on a surface facing the printed wiring board.   The heat insulating plate is a member having a thermal conductivity of 1.1 W / (mk) or less, and is composed of a member having a ratio of radiation having a wavelength of 1 μm or more included in radiation in the furnace atmosphere temperature of 30% or less. A reflow soldering method for a reflow soldering apparatus according to claim 4.

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