JP2008279502A - Reflow apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflow apparatus capable of maintain a large difference between the temperatures of adjacent zones. <P>SOLUTION: A reflow apparatus 100 has a plurality of chambers 111 arranged side by side and a conveying passage 107, which extends penetrating the chambers 111. The reflow apparatus 100 includes: an outside circulation duct 160, which forms an outside circulation path for allowing the atmosphere in the plurality of chambers 111 to flow out from the chambers 111 and allowing it again to flow into each of the plurality of chambers 111; a cooling means 164 for cooling the atmosphere passing through the outside circulation path; a flowrate control valve 171 capable of controlling the flowrate of the atmosphere flowing into each of the chambers 111; and a control means 200 for controlling the open degree of the flowrate control valve 171. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reflow apparatus for soldering a substrate on which a component is placed and the component, and in particular, a reflow for soldering a plurality of the substrate and the component (hereinafter referred to as “workpiece”) in-line. Relates to the device.

  Conventionally, in order to solder a workpiece industrially, an apparatus called a reflow apparatus including a preheating zone, a reflow zone, and a cooling zone in-line is used.

  The preheating zone of the reflow apparatus is a zone for raising the temperature of workpieces partially having different heat capacities as uniformly as possible, and is generally composed of a plurality of zones that gradually increase the ambient temperature. The atmospheric temperature of the entire preheat zone is set to a temperature lower than the atmospheric temperature of the reflow zone, that is, the temperature at which the solder melts.

  In the case of such a reflow apparatus, it is possible to provide good soldering by maintaining the atmospheric temperature of each zone in an appropriate temperature state. In particular, if the temperature difference between the zones is higher to some extent, the temperature of the workpiece can be increased efficiently and uniformly. However, if the temperature gradient of the adjacent zones is high, the amount of high temperature atmosphere flowing toward the low temperature atmosphere through the conveyance path increases, so it is difficult to maintain a high temperature difference between adjacent zones. Has been.

In Patent Document 1, a high-temperature atmosphere heated by an atmosphere heater is sprayed on a workpiece, and the workpiece is heated by a far-infrared heater, so that the workpiece can be directly applied by far-infrared without providing a large temperature difference in the ambient temperature of each zone. Has been proposed to be at a predetermined temperature.
JP-A-8-293666

  However, the far-infrared absorption efficiency varies greatly depending on the type of electronic component, and it is difficult to raise the temperature of the entire workpiece uniformly.

  Therefore, as a result of intensive research and efforts, the inventors of the present application returned to the origin of the reflow device in which the temperature of the workpiece is raised by heat exchange with the ambient temperature, and it is more difficult to lower the temperature than to raise the ambient temperature. In view of the above, the inventors have found an efficient temperature lowering means and a temperature lowering method, thereby completing the present invention.

  That is, an object of the present invention is to provide a reflow apparatus that can maintain a high temperature difference between adjacent zones.

  Furthermore, when switching the type of work to be soldered by the reflow device, the ambient temperature in each zone may have to be lower than the current state. In this case, in order to shorten the time when switching the work type, the compressed air supplied to the entire factory is forcibly introduced into the reflow device, or the chamber of the reflow device is opened to open the reflow device. May be exposed to the atmosphere.

  However, the inside of the high-temperature reflow device is blown with compressed air, which may be dangerous such as high-temperature air blowing out. In addition, when the inside of a high-temperature reflow device is exposed to the atmosphere, it becomes dangerous because a human body can also come into contact. Furthermore, in order to introduce the compressed air into the reflow device, a separate device is required, which increases the cost.

  Another object of the present invention is to provide a temperature switching method that can safely and quickly lower the temperature inside the reflow apparatus when the workpiece is switched.

  In order to achieve the above object, a reflow apparatus according to the present invention is a reflow apparatus having a plurality of chambers arranged in parallel and having a conveyance path extending through the chambers, wherein the atmosphere in the plurality of chambers is changed. An external circulation duct that forms an external circulation path that is led out of the chamber and introduced again into each of the plurality of chambers, a cooling unit that cools an atmosphere that passes through the external circulation path, and is introduced into each chamber. A flow control valve capable of controlling the flow rate of the atmosphere; and a control means for controlling the opening of the flow control valve.

  As a result, the amount of the atmosphere cooled in the external circulation path can be controlled in each chamber, the temperature of the chamber to be lowered can be lowered efficiently, and the temperature in the chamber can be maintained at a predetermined temperature. Become.

  In addition, since the temperature can be lowered efficiently and safely, the time can be shortened when the type of workpiece is switched.

  Furthermore, it may include a blowing unit that generates a wind that forcibly circulates the atmosphere in the outer circulation path, and the control unit may control a total air volume of the blowing unit.

  As a result, the amount of the low temperature atmosphere introduced can be controlled more positively.

  Furthermore, a temperature measuring means for measuring the temperature in each chamber may be provided, and the control means may control the opening degree of the flow rate control valve based on the measured value of the temperature measuring means.

As a result, the temperature in the chamber can be maintained at a set value in a fine manner.
In order to achieve the above object, a temperature adjustment method according to the present invention is a temperature adjustment method for the reflow apparatus, wherein a set temperature acquisition step for acquiring a set temperature of each chamber and a temperature in the chamber are set. A search step for searching for a chamber that is greater than or equal to the value and has a tendency to rise, and an introduction amount increase step for increasing the introduction amount for introducing the atmosphere cooled in the outer circulation path to the chamber searched in the search step Are preferably included.

The operation and effect of the method are the same as described above.
Furthermore, the temperature switching method according to the present invention is for the reflow apparatus, a production condition acquisition step for acquiring a production condition corresponding to a new substrate, and a set temperature for acquiring a set temperature of each chamber from the production condition. An acquisition step, a search step for searching for the presence of a chamber whose temperature is higher than the acquired set temperature, and an atmosphere cooled in the external circulation path for the chamber searched in the search step. And an introduction amount increasing step for maximizing the introduction amount to be introduced.

  As a result, even when it is necessary to lower the set temperature of the chamber when switching the type of workpiece, the temperature can be lowered in a closed circuit state without blowing out hot air, so that the set temperature can be safely and early. The temperature can be lowered.

  According to the present invention, the temperature difference between adjacent sections can be maintained in a high state, and the reflow process can be performed under suitable temperature conditions.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing the entire reflow apparatus 100 in cross section.

  As shown in the figure, the reflow apparatus 100 is an apparatus that uses air as a heat medium and solders a mounted electronic component to a circuit board (hereinafter referred to as “work”), and includes a first preheating zone 110. , A second preheating zone 120, a reflow zone 130 and a cooling zone 140. Each of such zones 110, 120, 130, and 140 is formed by an independent chamber.

  The reflow apparatus 100 performs a soldering process while the work 105 moves from the left to the right in the figure by a conveyor 107 as a conveyance path extending through the reflow apparatus 100, and carries out the work 105 in a low temperature state. is there.

  Specifically, the workpiece 105 is heated in the atmosphere of the first preset temperature by passing through the first preheating zone, and then the workpiece 105 is brought into the second preset temperature by passing through the second preheating zone. Heating is performed in an atmosphere of (first set temperature <second set temperature). Thus, by heating the workpiece | work 105 in steps, the electronic component from which a heat capacity differs can be heated up uniformly. Then, the solder is melted in the reflow zone 130 at the third preset temperature (second preset temperature <third preset temperature), and the entire workpiece 105 is slowly cooled while the solder is solidified in the cooling zone 140.

  The reflow apparatus 100 includes a first preheating chamber 111, a second preheating chamber 121, a reflow chamber 131, a cooling chamber 141, an external circulation duct 160, an external circulation fan 161, a labyrinth 162, a mesh filter 163, A water cooling jacket 164 and flow rate control valves 171, 172, 173, 174 are provided.

  Each chamber 111, 121, 131, 141 is a member for maintaining the internal atmosphere at a predetermined temperature, and employs a heat insulating structure that suppresses mutual heat conduction. In addition, each chamber 111, 121, 131, 141 is modularized, and the length of each zone 110, 120, 130, 140 can be easily changed by adding each chamber 111, 121, 131, 141. It has become something that can be done.

  The external circulation duct 160 is a member that forms an external circulation path for circulating the atmosphere (exhaust gas) discharged from the chambers 111, 121, 131, 141.

  The water cooling jacket 164 is a cooling means for cooling the exhaust passing through the labyrinth 162 and the filter 163 and aggregating flux in the exhaust.

  The labyrinth 162 causes the exhaust from each of the chambers 111, 121, 131, 141 to meander in a complicated manner, and increases the amount of exhaust that comes into contact with the water cooling jacket 164.

  The mesh filter 163 is a filter that collects the flux aggregated in the exhaust gas due to the temperature drop of the exhaust gas.

  The flow rate control valves 171, 172, 173, and 174 are used to select the chambers 111, 121, 131, and 141 for returning the exhaust gas when returning the exhaust gas whose temperature is decreased and flux is removed to each of the chambers 111, 121, 131, and 141. And a valve capable of adjusting the flow rate of exhaust gas to be returned. The flow control valves 171, 172, 173, and 174 can independently control the opening degree by a control unit described later. That is, the flow rate of the exhaust gas introduced into each chamber 111, 121, 131, 141 is adjusted independently by the control unit.

FIG. 2 is a cross-sectional view of the chamber viewed from the phase direction of the workpiece.
As shown in the figure, the reflow apparatus 100 includes a heater 151, an internal circulation fan 152, and a hot air nozzle 153 in the heating system chambers 111, 121, and 131. In the reflow device 100, a heater 151, an internal circulation fan 152, and a hot air nozzle 153 are provided on the opposite side of the conveyor 107.

  Hereinafter, the internal structure of the chamber will be described for the reflow chamber 131. The other heating system chambers 111 and 121 have the same structure.

  The heater 151 is a heater that heats the atmosphere cooled through the outer circulation duct 160 and re-introduced into the chamber 131 and the atmosphere that circulates independently in the chamber 131. The heater 151 includes a plurality of coils wound in a coil shape. Nichrome wires are arranged at predetermined intervals. The output of the heater 151 can be controlled by a control unit described later.

  The internal circulation fan 152 is a fan for independently circulating the atmosphere in the chamber 131 and is a sirocco fan that is rotated by a motor 154 provided outside the chamber 131.

  The hot air nozzle 153 is a member provided with many thin holes for blowing the atmosphere heated by the heater 151 and blown by the internal circulation fan 152 to the workpiece 105 at a predetermined wind speed.

  The chamber 131 further has a filter-like shape in which a blade 155 for rectifying the atmosphere blown by the internal circulation fan 152 and a catalyst (thermal catalyst) for decomposing flux evaporated by heating in the atmosphere are supported. A carrier 156 is provided.

  A part of the atmosphere in the chamber 131 is led out of the chamber 131 by the exhaust duct 165. The derived atmosphere is provided to the external circulation path.

  In the figure, a blackish arrow indicates a flow of a relatively high temperature atmosphere, and a whitish arrow indicates a flow of a relatively low temperature atmosphere.

FIG. 3 is a block diagram illustrating a control unit of the reflow apparatus.
As shown in the figure, the reflow device 100 includes a control unit 200 that controls mechanical units such as flow rate control valves 171, 172, 173, and 174. The control unit 200 is realized by a computer.

  The thermocouple 157 is a sensor that measures the temperature of hot air near the outlet of the hot air nozzle 153. The oxygen concentration measuring means 158 is a sensor that is provided at the carry-in port and the carry-out port of the workpiece 105 and measures the oxygen concentration.

  The heater control unit 251 is a processing unit that controls output to the heater 151 based on an instruction from the calculation unit 201.

  The fan control unit 261 is a processing unit that controls the rotational speed of the external circulation fan 161 based on an instruction from the calculation unit 201.

  The flow rate control unit 271 is a processing unit that independently controls the opening degrees of the flow rate control valves 171, 172, 173, and 174 based on instructions from the calculation unit 201.

  The calculation unit 201 is a processing unit that gives instructions to each processing unit by a predetermined program based on the measurement values of the thermocouple 157 and the oxygen concentration measuring unit 158.

Next, a method for controlling the temperature of each chamber will be described.
FIG. 4 is a flowchart showing a method for controlling the temperature of each chamber.

  In the method described here, the amount of exhaust gas introduced into each chamber 111, 121, 131, 141 is controlled by controlling each flow control valve 171, 172, 173, 174, and the adjacent chamber (zone) 111 is controlled. , 121, 131, 141 maintain a high temperature difference.

First, the set temperature in each heating system chamber 111, 121, 131 is input.
The calculation unit 201 turns on the heaters 151 provided in the heating system chambers 111, 121, 131 via the heater control unit 251 (S104). The computing unit 201 determines whether the temperature in each heating system chamber 111, 121, 131 has reached the set value based on the measured value from the thermocouple 157 (S107).

  When the temperature in each heating system chamber 111, 121, 131 reaches the set value (S107: Y), the chamber in which the current temperature exceeds the set temperature and the heater output is 0 continues for 1 minute or longer. (S110). The time is measured by a timer (not shown) held by the calculation unit 201.

  If a chamber in which the current temperature exceeds the set temperature and the heater output is 0 is confirmed for one minute or longer (S110: Y), then whether or not the current temperature of the chamber is decreasing is determined. It is determined (S113).

  Next, when the temperature of the target chamber rises despite the output of the heater 151 being 0 (S113: N), the flow rate control valve of the target chamber is opened one step (S116). That is, the amount of exhaust gas cooled by the water cooling jacket 164 flows into the target chamber increases.

  Next, even if the flow control valve is opened one step, if the temperature of the target chamber does not begin to fall within 1 minute (S119: N), it is confirmed whether the opening of the flow control valve is maximum (S120). In the case of the maximum degree (S120: Y), the calculation unit 201 increases the rotational speed of the external circulation fan 161 by one step via the fan control unit 261, and all of the currently open (not opening degree 0). The flow rate control valve is opened from the fully closed position to the one-stage open state (minimum opening: the smallest opening whose opening is not 0) (S122).

  Next, if the state in which the temperature of all the chambers is maintained at the set value continues for 1 minute or longer (S125: Y), this process ends. If not continued (S125: N), the process returns to step 107 (S107). Repeat the process.

  By the above processing, a relatively low temperature atmosphere is introduced into the chamber in which the temperature rises even when the output to the heater 151 is 0, that is, the chamber in which the temperature rises due to the flow of the high temperature atmosphere from the adjacent chamber. Since the temperature can be forcibly lowered, the temperature of each chamber can be maintained at the set value even if the temperature difference between adjacent chambers is large.

  Further, by introducing more exhaust gas into the chamber whose temperature is to be set lower, the pressure in the chamber becomes higher than that of the adjacent high temperature chamber, and the inflow of the atmosphere from the high temperature chamber can be suppressed by the pressure difference.

  Moreover, since the exhaust gas introduced into the chamber is forcibly cooled by the water cooling jacket 164, the temperature is constant and the temperature in the chamber can be maintained stably. Further, since the temperature is not as low as that in the atmosphere, the temperature in the chamber can be easily adjusted.

  On the other hand, when the air is introduced into the chamber for cooling, the temperature to be introduced in the season or time is not constant, so that it is difficult to maintain the temperature in the chamber with constant software (parameters). In addition, since it is necessary to introduce a low-temperature atmosphere of 40 ° C. or less, the temperature difference between the set value and the atmosphere to be introduced is too large, and it becomes difficult to keep the temperature in the chamber constant.

Incidentally, in the present embodiment, the temperature of the exhaust gas introduced into the chamber is 80 ° C. or higher.
Furthermore, in the case of a reflow apparatus that maintains the inside of the chamber in a low oxygen atmosphere, the exhaust introduced to cool the chamber is also in a low oxygen state, so that the work 105 can be affected more than when air is introduced. It becomes possible to keep it as low as possible.

  Next, a processing procedure for changing the temperature state of the reflow apparatus 100 when switching a workpiece to be processed that can be realized by the apparatus configuration of the present embodiment will be described.

  FIG. 5 is a flowchart showing a processing procedure for changing the temperature state of the reflow apparatus 100 when switching the workpiece to be processed.

  As shown in the figure, the reflow apparatus 100 acquires a new production condition (set temperature of the chamber) corresponding to the new workpiece 105.

  Next, the presence of a chamber in which the current chamber temperature is higher than the acquired set temperature is searched (S204).

  When a chamber having a temperature higher than the set temperature exists (S204: Y), the flow control valve of the target chamber is fully opened, and the rotational speed of the external circulation fan 161 is set to the highest speed (S207). That is, only the target chamber is rapidly cooled.

  Next, the chamber in which the flow rate control valve is open even though the temperature in the chamber is equal to or lower than the set value is searched (S210). If there is a corresponding chamber (S210: Y), the target flow control valve is fully closed (S213), and if there is not (S210: N), the routine proceeds to a normal startup procedure.

  By performing the processing as described above, the temperature state of the reflow apparatus 100 can be flexibly changed even when the type of the workpiece 105 is switched. In particular, when the set temperature is lower than before, only the chamber higher than the set temperature can be rapidly cooled, and the temperature state of the reflow apparatus can be quickly changed when the type of the workpiece 105 is switched. .

  On the other hand, conventionally, waiting for the natural heat release of the reflow device 100 or opening the lid of the reflow device 100 to introduce a large amount of air, cooling the reflow device 100 once, and then raising the temperature again, a new work 105 It corresponds to. When waiting for the above natural heat dissipation, a long time is required, and the mounting line including other component mounting machines is idle, which adversely affects the cost. In addition, the act of opening the lid of the reflow device 100 has a bad influence on the device, for example, fatigue is accumulated in metal parts and the like because the temperature of the reflow device 100 changes abruptly. In addition, when the reflow apparatus 100 is operated in a low oxygen state, the low oxygen state must be canceled once, so that time and cost for making the low oxygen state again become necessary.

  Next, a processing method for reducing the replenishment amount of nitrogen gas when introducing nitrogen gas to make the inside of the reflow apparatus 100 into a low oxygen atmosphere will be described.

  FIG. 6 is a flowchart showing a processing procedure for reducing the replenishment amount of nitrogen gas to the reflow device as much as possible.

  First, the oxygen concentration measurement means 158 measures the oxygen concentration at the entrance where the work 105 is carried into the reflow apparatus 100 and at the exit where the work 105 is carried out (S301). When the oxygen concentration at the inlet is higher than the oxygen concentration at the outlet (S304: Y), the flow control valve on the outlet side is closed by one stage and the flow control valve on the inlet side is opened by one stage (S307).

  Next, when the oxygen concentration at the inlet is lower than the oxygen concentration at the outlet (S310: Y), the flow control valve on the inlet side is closed by one stage, and the flow control valve on the outlet side is opened by one stage (S313).

  Next, when the current oxygen concentration is higher than the designated oxygen concentration (S316: Y), the nitrogen supply valve is opened one step (S319).

  Next, when the current oxygen concentration is lower than the designated oxygen concentration (S322: Y), the nitrogen supply valve is closed by one step (S325).

  If it processes as mentioned above, a big flow of nitrogen gas in reflow device 100 can be controlled, and it becomes possible to control leakage of nitrogen gas from an exit or an entrance. Therefore, the supply amount of nitrogen gas for maintaining the reflow device 100 in a low oxygen state can be kept low.

  In the present embodiment, the number of chambers of the reflow apparatus 100 is four. However, the number of chambers of the reflow apparatus 100 according to the present invention is not limited to four, and an arbitrary number can be selected. Further, by preparing a unit in which two chambers are arranged in parallel and a unit in which three chambers are arranged in parallel, it becomes possible to flexibly assemble the reflow apparatus 100 having various numbers of chambers.

  The present invention can be applied to a reflow apparatus.

It is sectional drawing which shows the whole reflow apparatus 100 in a cross section. It is sectional drawing which desires a chamber from the phase direction of a workpiece | work. It is a block diagram which shows the control part of a reflow apparatus. It is a flowchart which shows the control method of the temperature of each chamber. It is a flowchart which shows the process sequence which changes the temperature state of the reflow apparatus 100 at the time of switching the workpiece | work to process. It is a flowchart which shows the process sequence for reducing the replenishment amount of the nitrogen gas to a reflow apparatus as much as possible.

Explanation of symbols

100 reflow device 105 work 107 conveyor 110 first preheating zone 111 first preheating chamber 120 second preheating zone 121 second preheating chamber 130 reflow zone 131 reflow chamber 140 cooling zone 141 cooling chamber 151 heater 152 internal circulation fan 153 hot air nozzle 154 motor 155 Blade 156 Carrier 157 Thermocouple 158 Oxygen concentration measuring means 160 Outer circulation duct 161 Outer circulation fan 162 Labyrinth 163 Filter 164 Water cooling jacket 165 Exhaust ducts 171, 172, 173, 174 Flow rate control valve 200 Control unit 201 Calculation unit 251 Heater control 261 Fan control unit 271 Flow rate control unit

Claims (8)

A reflow apparatus including a plurality of chambers arranged in parallel and having a conveyance path extending through the chambers,
An external circulation duct for deriving the atmosphere in the plurality of chambers out of the chamber and forming an external circulation path for introducing the atmosphere into each of the plurality of chambers again;
Cooling means for cooling the atmosphere passing through the outer circulation path;
A flow control valve capable of controlling the flow rate of the atmosphere introduced into each chamber;
A reflow apparatus comprising control means for controlling the opening degree of the flow control valve. further,
Air blowing means for generating wind for forcibly circulating the atmosphere in the external circulation path;
The reflow apparatus according to claim 1, wherein the control unit controls a total air volume of the blowing unit. further,
Comprising temperature measuring means for measuring the temperature in each chamber;
The reflow apparatus according to claim 1, wherein the control unit controls an opening of the flow control valve based on a measurement value of the temperature measuring unit. A temperature adjustment method for the reflow device according to claim 1,
A set temperature acquisition step for acquiring a set temperature of each chamber;
A search step of searching for a chamber in which the temperature in the chamber is equal to or higher than a set value and tends to rise;
A temperature adjustment method including an introduction amount increasing step of increasing an introduction amount for introducing the atmosphere cooled in the outer circulation path into the chamber searched in the searching step.   The temperature adjustment method according to claim 4, wherein the increase in the introduction amount is achieved by increasing the opening degree of the flow control valve.   The temperature adjustment method according to claim 4, wherein the increase in the introduction amount is achieved by increasing the total air volume of the air blowing means. further,
The temperature adjustment method according to claim 6, wherein an opening degree of the flow control valve is set to a minimum opening degree. A plurality of chambers are arranged in parallel, and a conveyance path extending through the chambers and an external circulation path for deriving the atmosphere in the plurality of chambers out of the chambers and introducing them into the plurality of chambers again are formed. An outer circulation duct, a cooling means for cooling the atmosphere passing through the outer circulation path, a flow rate control valve capable of controlling the flow rate of the atmosphere introduced into each chamber, and a control for controlling the opening degree of the flow rate control valve A temperature switching method when switching the type of substrate to be soldered by a reflow apparatus comprising means,
A production condition acquisition step for acquiring a production condition corresponding to a new board;
A set temperature acquisition step of acquiring the set temperature of each chamber from the production conditions;
A search step for searching for the presence of a chamber whose current chamber temperature is higher than the acquired set temperature;
A temperature switching method including an introduction amount increasing step for maximizing an introduction amount for introducing the atmosphere cooled in the outer circulation path into the chamber searched in the searching step.

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