JPH08195552A - Method and device for reflow soldering - Google Patents

Abstract

PURPOSE: To achieve a uniform heating and proper heating profile and to properly solder all kinds of wiring boards by accurately and easily controlling the amount of heat transfer to the wiring board from hot air and that from infrared rays independently. CONSTITUTION: An atmosphere for heating a wiring board 1 carried by a carrying conveyor 27 is circulated by a centrifugal blower 36 and is heated by a heater 39 for heating atmosphere, the amount of circulated and blown air is adjusted, and at the same time the temperature of atmosphere is detected by a sensor 42 for measuring atmospheric temperature for controlling the amount of convection heat transfer, and the temperature of an infrared ray heater 40 for heating the wiring board 1 is detected by a sensor 43 for measuring surface temperature to control the amount of radiant electric heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow soldering method and apparatus for heating and melting solder previously supplied to a wiring board for soldering.

[0002]

2. Description of the Related Art When reflow soldering equipment is roughly classified,
It can be classified into an infrared heating type reflow soldering device that heats a wiring board with infrared rays and a hot air heating type reflow soldering device that heats a wiring board with hot air.

FIG. 4 is a side sectional view showing a conventional infrared heating type reflow soldering apparatus. FIG.
It is an excerpt from Japanese Patent Publication No. 19 (publicly known example 1). That is,
This is a device for performing reflow soldering by heating the wiring board 1 carried by the carrying conveyor 3 in the heating furnace 2 with infrared rays radiated from the planar heater 4.

In the infrared heating type reflow soldering apparatus, since the amount of radiant heat transfer to the wiring board 1 is approximately proportional to the surface temperature of the heater to the fourth power, the temperature of the wiring board 1 tends to rise excessively. Therefore, it is necessary to measure the temperature of the wiring board 1 with the radiation thermometer 5 or the like and adjust the heater power so as to obtain a desired heating profile. By the way, in the technique of the known example 1, the planar heater 4 is provided with a hole 6 for measuring the temperature of the wiring board 1, and the temperature of the wiring board 1 is measured from this hole 6 by using a radiation thermometer. There is a feature in that.

FIG. 5 is a side sectional view showing a conventional hot-air heating type reflow soldering device. FIG. 5 is a view of Japanese Unexamined Patent Publication No. 6-8706.
It is an excerpt from Japanese Patent Publication No. 8 (publicly known example 2). That is, the wiring board 1 conveyed by the conveyor 3 in the heating furnace 11.
To the blower 1 for the atmosphere (hot air) heated by the heater 12.
It is a reflow soldering device that sprays and heats at 3.
Then, in the technique of the known example 2, the infrared control body 1 for controlling the infrared irradiation amount between the heater 12 and the wiring board 1.
The feature is that 4 is openable and closable.

In the hot air heating type reflow soldering apparatus,
Since the amount of heat transferred to the wiring board 1 is defined by the hot air temperature and the air flow rate (surface wind speed of the wiring board 1), there is an advantage that it is not essentially heated above the hot air temperature and the risk of overheating is low.
However, the rate of temperature rise tends to be high in a part covered with a metal having a high thermal conductivity. Therefore, infrared heating is also used to reduce the difference in temperature rising rate due to the difference in parts. That is, this is a technique in which the infrared controller 14 controls the amount of infrared rays emitted from the heater 12 for heating the atmosphere to the wiring board 1 so that the infrared heating can be used together with the hot air heating.

On the other hand, when hot air heating and infrared heating are used together, a heater 12 for hot air heating and an infrared heater (not shown) for heating a wiring board are separately provided, and the electric power of each heater is controlled to perform heating. There is also a reflow soldering device configured to adjust the heating amount of. In the case of such a reflow soldering device, the temperature of the hot air blown to the wiring board is detected by a sensor and the power applied to the atmosphere heating heater is controlled so that this temperature becomes constant at the target value. Feedback control is not performed on the electric power applied to the heater, but the infrared irradiation amount is adjusted by performing open control on the target applied electric power. This configuration is based on the technical idea of supplementarily using infrared heating.

The quantitative analysis of the heating / heat transfer characteristics of the infrared heating type reflow soldering apparatus and the hot air heating type reflow soldering apparatus as described above, and the necessity of the combined use of hot air and infrared rays are described in the Nikkan Kogyo Shimbun. "Surface mounting technology reader" (edited by Satoshi Ito, June 10, 1993)
It is also disclosed in detail in P149 to P152 7.2.2 Infrared reflow furnace and 7.2.3 Hot air reflow furnace of the first edition, first printing).

[0009]

[Patent Document 1] Japanese Patent Application Laid-Open No. 6-87068
The technique of Japanese Patent Publication (Publication 2) has the advantage that the same heater 12 can perform atmospheric heating and infrared heating of the wiring board 1, but the atmospheric heating temperature (hot air temperature) and the infrared rays to the wiring board 1 can be used. There is a disadvantage that the irradiation dose cannot be controlled independently. This is because, for example, if the temperature of the heater 12 is raised to raise the ambient temperature, the amount of infrared radiation from the heater 12 also increases and the amount of heat transfer by infrared rays to the wiring board 1 also increases.

Further, in the technique of separately providing an infrared heater and applying a desired constant electric power to the infrared heater, when the wiring substrate 1 is transported, the surface temperature of the infrared heater is lowered and is not transported. If the surface temperature rises. In addition, the surface temperature of the infrared heater also changes when the hot air volume and hot air temperature are adjusted and varied. by the way,
The amount of heat transferred from the infrared heater to the wiring board is regulated by the fourth power of the surface temperature of the infrared heater. Therefore, if the size of the wiring board or the transport tact changes or the hot air temperature or air volume is adjusted, the infrared heater To the wiring board also changes, and as a result, the ratio of the heat transfer quantity by the hot air and the heat transfer quantity by the infrared ray changes, and it becomes impossible to uniformly heat the wiring board.

Further, when the surface temperature of the infrared heater changes, the ambient temperature also changes under the influence of it, so that the electric power applied to the heater for heating the atmosphere is controlled so as to keep the ambient temperature constant. Therefore, every time the wiring board is conveyed, the surface temperature of the infrared heater changes, and accordingly, the electric power applied to the atmosphere heating heater is controlled so as to make the atmosphere temperature constant. Therefore, the amount of heat transfer by the hot air and the amount of heat transfer by the infrared light constantly fluctuate, which hinders uniform heating of the wiring board and reproducibility of the heating profile.

An object of the present invention is to establish a reflow soldering method capable of independently and stably controlling the amount of heat transfer to the wiring board by hot air and the amount of heat transfer to the wiring board by infrared rays. We have realized a reflow soldering device that can achieve uniform heating and an optimum heating profile in response to changes in size, size, and types of components mounted on wiring boards, and high-quality solder for all wiring boards. It is in the place that can be attached.

[0013]

[Means for Solving the Problems] Claim 1 according to the present invention
In the invention described in, the atmosphere in the heating furnace is circulated by an atmosphere circulation means, the circulating atmosphere is heated by a heater for heating the atmosphere to make the atmosphere hot air, and the hot air and infrared rays generated by an infrared heater are used for wiring. The substrate is heated, and the convective heat transfer amount is controlled based on at least one of the temperature of the hot air blown onto the wiring board and the amount of air blown by the atmosphere circulation means,
Further, the amount of radiant heat transfer is controlled based on the surface temperature of the infrared heater, and the amount of air blown by the atmosphere circulating means, the temperature of the hot air blown on the wiring board, and the surface temperature of the infrared heater are controlled independently of each other.

Further, the invention according to claim 2 controls the electric power applied to the heater for heating the atmosphere by referring to the detected value of the sensor for measuring the temperature of the hot air, so that the temperature of the hot air blown onto the wiring board is desired to be constant. In addition to controlling the temperature, the power applied to the infrared heater is controlled by referring to the detection value of the sensor for measuring the surface temperature of the infrared heater to control the surface temperature of the infrared heater to a desired constant value.

In the invention according to claim 3, an atmosphere circulation passage formed by partitioning the inside of the heating furnace with a partition member, an atmosphere circulation means for circulating the atmosphere in this atmosphere circulation passage, and an atmosphere circulation passage. A transport conveyor that transports the wiring substrate across the path, an infrared heater that allows circulation of the atmosphere in the vicinity of at least one surface of the wiring substrate transported by the transport conveyor, and also as seen from the wiring substrate. A heater for atmosphere heating arranged in the atmosphere return passage corresponding to the back side of the partition member, a sensor for measuring the surface temperature of the infrared heater, and a circulating atmosphere on the wiring board. An ambient temperature measuring sensor for detecting the hot air temperature of the atmosphere, which is provided in the vicinity of the surface side, and an instruction input section for setting the surface temperature of the infrared heater, and an infrared heater. Temperature that controls the electric power control unit so that the electric power control unit that adjusts the electric power supplied to the controller and the instruction value of the instruction input unit and the detection value of the surface temperature detection sensor of the infrared heater are compared A control unit, an instruction input unit for setting the atmosphere temperature, a power control unit for adjusting the electric power supplied to the atmosphere heating heater, and an instruction value of the instruction input unit and a detection value of the hot air temperature detection sensor are compared. And a temperature control unit that controls a power control unit that adjusts the power supplied to the heater for heating the atmosphere so that the two values match.

According to the invention described in claim 4, the atmosphere circulation means is constructed so that the amount of air blown is variable.

[0017]

According to the first aspect of the present invention, the amount of heat transferred from the hot air to the wiring board is defined by the hot air temperature, that is, the ambient temperature, provided that the speed of the hot air is constant, and is derived therefrom. Conversely, if the hot air temperature is constant,
It is regulated by the air flow rate and is derived from it.

On the other hand, the amount of heat transferred by the infrared rays (heat rays) to the wiring board is defined by the surface temperature of the infrared heater and is derived therefrom.

By independently controlling the hot air temperature, the air flow rate, and the surface temperature of the infrared heater, the magnitudes and ratios of the convective heat transfer quantity and the radiant heat transfer quantity can be set accurately and easily according to the type of the wiring board. be able to.

Therefore, it is possible to easily obtain the desired heating profile while uniformly heating the individual components mounted on the wiring board.

Further, according to the second aspect of the invention, since the surface temperature of the infrared heater is controlled to the target constant temperature, the surface temperature of the infrared heater is determined by the presence / absence of the wiring board, the hot air temperature, and the air blowing amount thereof. As a result, the amount of heat transferred by infrared rays to the wiring board can be maintained at a target constant value. Further, by keeping the surface temperature of the infrared heater constant, it is possible to eliminate unnecessary control operations such as canceling out disturbance factors to the ambient temperature by the infrared heater.

Therefore, the temperature of the hot air blown onto the wiring board and the infrared rays irradiated are extremely stabilized, and the ratio of the two heat transfer amounts is also very stable. That is, it is possible to realize a heating environment with good controllability. As a result, it is possible to easily obtain a desired heating profile while accurately and uniformly raising the temperature of each component mounted on the wiring board.

According to the third aspect of the present invention, the atmosphere in the furnace body is circulated by the atmosphere circulation means and blows against the wiring substrate conveyed by the conveyor. The circulating atmosphere is heated by the heater for heating the atmosphere, but the infrared rays radiated from the heater are blocked by the partition member and are not irradiated on the wiring board. Therefore, the circulating atmosphere, that is, the hot air heats the wiring board. On the other hand, infrared rays radiated from the infrared heater irradiate the wiring board to heat the wiring board. Of course, when both surfaces of the wiring board are heated by infrared rays, infrared heaters are respectively provided near the respective surfaces to perform infrared heating.

The temperature of the hot air blown on the wiring board is detected by the sensor for measuring the ambient temperature, and the surface temperature of the infrared heater is detected by the sensor for measuring the surface temperature. Then, the temperature control unit controls the electric power control unit while referring to the sensor output so that the hot air temperature matches the instruction value of the instruction input unit, and the electric power control unit controls the heater electric power. Similarly, regarding the surface temperature of the infrared heater, the temperature control unit controls the power control unit while referring to the sensor output so as to match the instruction value of the instruction input unit, and the power control unit controls the infrared heater power. Control.

Therefore, the hot air temperature and the surface temperature of the infrared heater are independently controlled according to the set value of the instruction input section, and the heat transfer amount to the wiring board by the hot air and the heat transfer amount to the wiring board by the infrared ray are independently controlled. Can be controlled and adjusted to

As a result, the type of the wiring board, that is, the mounting amount and the mounting type of the component, whether it is mounted on only one side or both sides, the thermal conductivity and the infrared absorption rate of each mounted component. In consideration of the differences between the two, it is possible to optimally adjust the amount of heat transfer due to hot air and the amount of heat transfer due to infrared rays, and the ratio of these heat transfer amounts. Can be heated.

Further, in the invention described in claim 4, in addition to the operation of claim 3, it becomes possible to adjust the convective heat transfer amount by the air flow rate, and the hot air temperature and the air flow rate thereof, and the infrared heater. By controlling the three surface temperatures independently of each other, the control and control range of the amount of convective heat transfer and the amount of radiant heat transfer, and the ratio of the two, becomes wider,
And it will be good.

[0028]

EXAMPLES Next, practical examples of how the reflow soldering method and reflow soldering apparatus according to the present invention can be embodied will be described.

FIG. 1 is a side sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II of FIG. That is, reference numeral 21 denotes a heating furnace, which constitutes a furnace body 26 from a preheating section 24 composed of two chambers of a temperature raising section 22 and a soaking section 23 and a reflow section 25 composed of one chamber. The wiring board 1 is conveyed through the conveyor 27 of the wiring board 1 and the wiring board 1 is sequentially heated. In addition,
The labyrinth portion 3 in which the labyrinth passages are formed by the inhibiting plates 30 on the carry-in port 28 side and the carry-out port 29 side of the furnace body 26, respectively.
1, 32 are provided.

As shown in FIG. 2, a guide plate 33 as a partition member is provided in each of the chambers 24 and 25 of the furnace body 26 to form an atmosphere circulation passage 34, and the atmosphere in this atmosphere circulation passage 34 is circulated. As a means, a centrifugal blower 36 is used to form the furnace body 2
The atmosphere is sucked in through the suction port 35 on the lower side of 6, and the atmosphere is recirculated from the recirculation path 37 to the upper side of the furnace body 26. The refluxed atmosphere subsequently descends and hits the wiring board 1,
The centrifugal blower 36 is sucked. The centrifugal blower 36 is rotationally driven by a motor 38.

The heater 39 for heating the atmosphere is arranged in the circulation path 37 of the atmosphere, that is, the portion corresponding to the back side of the guide plate 33 when viewed from the wiring board 1, and the infrared heater 40 faces each surface of the wiring board 1 and faces the same. Place in the vicinity. The infrared heater 40 is provided with a reflection plate 41, a pipe-shaped heater is coated with far-infrared radiation ceramics, and the infrared heaters 40 are arranged side by side along the conveyor 27. In this embodiment, the infrared heaters 40 are arranged on the upper side and the lower side of the wiring board 1 so that both surfaces of the wiring board 1 are heated by infrared rays. However, if only one surface of the wiring board 1 needs to be heated by infrared rays, the infrared heater 40 may be provided only on that surface side.

The temperature of the hot air blown on the wiring board 1 is measured by disposing an atmosphere temperature measuring sensor 42 near the surface of the wiring board 1 on which the hot air is blown, and the surface temperature of the infrared heater 40 is the surface temperature. Infrared heater 3 for measuring sensor 43
Fix it to 9 with a band and measure. Thermocouple sensors are used for these sensors 42 and 43.

FIG. 3 is a block diagram showing an example of the heater power control system and the air flow rate control system. The same reference numerals as those in FIGS. 1 and 2 indicate the same parts.

In this figure, 51 is a commercial power source, 52 is a power control unit of the heater 39 for heating the atmosphere, 53 is a power control unit of the infrared heater 40, and 54 is power control by detection of the sensor 42 for measuring the ambient temperature. A temperature control unit for controlling the unit 52, 55 a temperature control unit for controlling the power control unit 53 according to a detection signal of the surface temperature measuring sensor 43,
Reference numeral 56 is an instruction input unit for the temperature control unit 54, 57 is an instruction input unit for the temperature control unit 55, and 58 is a microcomputer system. Further, 61 is a rotation speed sensor for detecting the rotation speed of the blower 36, and 62 is the motor 3
8 is a motor drive control unit for controlling the number of revolutions, and 63 is a motor drive control unit 6 based on the detection signal of the rotation speed sensor 61.
Reference numeral 64 denotes a speed control unit for controlling 2, and 64 denotes an instruction input unit for the speed control unit 63. In addition, the same reference numerals as those in FIG. 2 indicate the same parts.

That is, the surface temperature value of the infrared heater 40 detected by the surface temperature measuring sensor 43 is determined by the temperature control unit 5.
In step 5, the electric power control unit 53 is compared with the instruction value of the instruction input unit 57 including, for example, a potentiometer so that both values become one value.
Is controlled to control the electric power supplied to the infrared heater 40.
That is, it constitutes a general feedback control system. The power control unit 53 is composed of a power control device such as SSR or SCR, and the temperature control unit 55 is composed of a PID control system or the like.

Further, the heater 39 for heating the atmosphere provided in the return path 37 is also controlled by the same control system, and the electric power control section 52 is so arranged that the hot air of the desired temperature indicated by the instruction input section 56 is blown onto the wiring board 1. To control.

Then, the rotation speed value of the blower 36 detected by the rotation speed sensor 61 is compared by the speed control unit 63 with the instruction value of the instruction input unit 64 including, for example, a potentiometer or the like, and the motor is adjusted so that both values match. The drive control unit 62 is controlled to control the rotation speed of the blower 36. The motor 3
If an induction motor is used for 8, the drive control unit 6
Speed control can be performed by using an inverter for No. 2. A PID control system or the like is used for the speed control unit 63.

Further, if necessary, a microcomputer system 58 is mounted, and the hot air temperature and the infrared heater 40 are provided.
The surface temperature (upper side and lower side) and the air flow rate data are input and stored in advance for each type of the wiring board 1.
For soldering, each instruction input section 5 is based on the data.
Instead of 6, 57 and 64, the temperature control units 54 and 55 and the speed control unit 63 may be instructed.

Next, the operation will be described.

A control system including the power control units 52 and 53, the temperature control units 54 and 55, and the instruction input units 56 and 57 controls the temperature (hot air) based on the detection values from the temperature measurement sensors 42 and 43. The electric power applied to each of the heaters 39 and 40 is controlled so that the temperature and the surface temperature of the infrared heater 40 are constant.

That is, these independent control systems independently control the ambient temperature of the wiring board 1, that is, the hot air temperature and the surface temperature of the infrared heater 40. Therefore, the amount of heat transfer to the wiring board 1 by the hot air and the amount of heat transfer to the wiring board 1 by the infrared rays can be controlled and adjusted independently. Further, since the surface temperature of the infrared heater 40 is controlled to be constant, the infrared heater 40 does not act as a disturbance factor to the ambient temperature, that is, the hot air temperature. That is, a heating process that is extremely stable and has good controllability is formed.

Further, a control system including a motor drive control unit 62, a speed control unit 63, and an instruction input unit 64,
The centrifugal blower 36 is based on the detected value from the rotation speed sensor 61.
The drive of the motor 38 is controlled so that the rotation speed of the motor becomes constant.

Here, an example of electronic components mounted on the wiring board 1 will be given to exemplify the case of uniform heating.

For example, SOP / IC and QF which are SMD
In P / IC and the like, the package is made of black epoxy resin or the like. Therefore, the package itself easily absorbs infrared rays, and the temperature rises quickly with respect to infrared heating.
However, when hot air is blown, the temperature rise of the package having a large heat capacity is slow.

Since the electrolytic capacitor is housed in the aluminum case, it reflects infrared rays and the temperature rises slowly with respect to infrared overheating. However, when hot air is blown, the temperature rise of the aluminum case having high thermal conductivity is fast.

Generally, since these parts are mounted together,
In order to heat these parts in the same manner to give the same heating profile and uniformly heat the entire wiring board 1, the surface area and volume of the SOP / IC and QFP / IC, the surface area and volume of the electrolytic capacitor, The amount of heat transfer by hot air and the amount of heat transfer by infrared rays and the ratio of the two are determined in consideration of the mounting ratio of components, and the hot air temperature and the surface temperature of the infrared heater are adjusted by the instruction input unit.

Further, for example, when there are many parts having a large volume and a large heat capacity, the desired convective heat transfer amount and the heating rate can be obtained by increasing the air flow rate of the hot air to accelerate the surface air velocity of the wiring board 1. Obtainable. Even in this case, uniform heating is possible by adjusting the amount of radiant heat transfer.

If the temperature distribution of the wiring board 1 is experimentally observed using thermography and the respective instruction input portions 56, 57 and 64 are adjusted and selected so as to eliminate the temperature unevenness, the amount of heat transferred by the hot air and The amount of heat transferred by infrared rays and the ratio of the two can be easily obtained, and the heating profile can be easily set.

By the way, in the reflow soldering apparatus of this embodiment, the heater 39 for heating the atmosphere is turned off, the operation of the centrifugal blower 36 is stopped, and the infrared heater 4 is operated.
When only 0 is operated, the infrared heating type reflow soldering device controls the surface temperature of the infrared heater 40 to be constant. On the contrary, when the infrared heater 40 is turned off, the hot air heating type reflow soldering device is obtained. Further, the wiring board 1 can be cooled by turning off both the heater 39 for heating the atmosphere and the infrared heater 40 and operating only the centrifugal blower 36.

Furthermore, it is possible not only to use hot air heating mainly for infrared heating as an auxiliary but also to use infrared heating mainly for hot air heating as an auxiliary, so that the object to be heated (wiring board 1 has a wide control range). It is possible to form a heating process having excellent adaptability to ().

As described above, the mounting amount of the type of the wiring board 1, that is, the type of component, whether it is mounted on only one surface or both surfaces, the thermal conductivity of each mounted component, In consideration of differences in infrared absorption rate, it becomes possible to optimally adjust the amount of heat transfer by hot air and the amount of heat transfer by infrared rays, and the ratio of these heat transfer amounts, so that the wiring board 1 is made uniform and It can be heated with the desired profile.

It should be noted that an acceleration / deceleration mechanism composed of, for example, a pulley or a belt may be provided between the motor 38 and the centrifugal blower 36, and the amount of air blown may be adjusted by adjusting the acceleration / deceleration ratio.

Further, the atmosphere circulation passage 34 may be provided with an orifice mechanism whose opening amount can be adjusted, and the blowing amount can be adjusted by adjusting the opening amount.

Further, a wind speed sensor is provided in the atmosphere circulation path 34, and based on the wind speed signal obtained from this sensor, the rotation speed of the centrifugal blower 36 or the acceleration / deceleration ratio of the acceleration / deceleration mechanism,
It is also possible to adjust the opening amount of the variable orifice mechanism to control it to a desired value.

The purpose of adjusting / controlling the air flow rate of the centrifugal fan 36 is to adjust and control the hot air velocity on the surface of the wiring board 1.

[0056]

As described above, according to the present invention, there are the following effects corresponding to each claim.

According to the first aspect of the present invention, the atmosphere in the heating furnace is circulated by the atmosphere circulation means, and the circulated atmosphere is heated by the heater for heating the atmosphere to make the atmosphere hot air. The wiring board is heated by the infrared rays generated from the infrared heater, and the convective heat transfer amount is controlled based on at least one of the temperature of the hot air blown onto the wiring board and the amount of air blown by the atmosphere circulation means, and based on the surface temperature of the infrared heater. Control the amount of radiant heat transfer
Since the amount of air blown by the atmosphere circulation means, the temperature of the hot air blown on the wiring board, and the surface temperature of the infrared heater are controlled independently of each other, the amount of heat transfer to the wiring board by hot air and the amount of heat transfer to the wiring board by infrared rays are independent. Can be controlled and adjusted. That is, the magnitudes and ratios of the two heat transfer amounts can be set accurately and easily according to the type of the wiring board.

Therefore, it becomes possible to obtain the desired heating profile while uniformly heating the individual components mounted on the wiring board, and to realize the reflow soldering process excellent in uniform heating property and heating controllability. be able to.

Further, the invention according to claim 2 controls the electric power applied to the heater for heating the atmosphere by referring to the detected value of the sensor for measuring the temperature of hot air, so that the temperature of the hot air blown onto the wiring board is a desired constant temperature. In addition to controlling the surface temperature of the infrared heater, the power applied to the infrared heater is controlled by referring to the detection value of the sensor for measuring the surface temperature of the infrared heater, and the surface temperature of the infrared heater is controlled to a desired constant value. Also, the surface temperature of the infrared heater can be controlled to a constant value irrespective of the atmospheric temperature and the air flow rate, and the amount of heat transferred to the wiring board by infrared rays can be controlled to a constant value. On the contrary, since the surface temperature of the infrared heater is constant, there is no disturbance factor that the infrared heater gives to the ambient temperature, and the ambient temperature, that is, the temperature of the hot air blown on the wiring board is extremely stabilized.

Therefore, the amount of heat transfer to the wiring board by the hot air and the amount of heat transfer by the infrared rays can be controlled and adjusted extremely accurately, easily and stably. As a result, it is possible to obtain the desired heating profile while accurately and uniformly raising the temperature of each component mounted on the wiring board. The heating uniformity and heating profile can be adjusted finely and stably with good reproducibility. A reflow soldering process that can be performed can be realized.

Further, according to the invention of claim 3, an atmosphere circulation passage formed by partitioning the inside of the heating furnace with a partition member, an atmosphere circulation means for circulating the atmosphere in this atmosphere circulation passage, and an atmosphere circulation passage. A transport conveyor that transports the wiring board across the wiring board, an infrared heater arranged to circulate the atmosphere in the vicinity of at least one surface of the wiring board transported by the transport conveyor, and also seen from the wiring board. An atmosphere heating heater arranged in an atmosphere circulation path corresponding to the back side of the partition member, a surface temperature measuring sensor for detecting the surface temperature of the infrared heater, and a surface on which the circulating atmosphere blows against the wiring board. On the other hand, in the vicinity thereof, an atmosphere temperature measuring sensor for detecting the hot air temperature of the atmosphere, on the other hand, an instruction input unit for setting the surface temperature of the infrared heater, and an infrared heater. Power control unit that adjusts the power supplied to the power control unit, and the temperature that controls the power control unit so that the instruction value of the instruction input unit and the detection value of the surface temperature detection sensor of the infrared heater are compared and both values match. A control unit, an instruction input unit that sets the ambient temperature, an electric power control unit of the atmosphere heating heater that adjusts the power supplied to the atmosphere heating heater, an instruction value of the instruction input unit and a detection value of the hot air temperature detection sensor And a temperature control unit that controls a power control unit that adjusts the electric power supplied to the heater for heating the atmosphere so that the two values match, so that the hot air temperature in the same atmosphere in the same furnace And the surface temperature of the infrared heater can be adjusted and controlled independently, and even if the load of the reflow soldering device, that is, the presence or absence of the wiring board or the change of the transport tact, is transmitted to the wiring board by hot air. It is possible to stably hold the amount of heat transferred to the quantity and infrared by the wiring board,
They can be accurately and easily controlled and adjusted independently.

Therefore, the wiring board structure state (both sides,
According to one side, type of mounted components, number of mounted components, etc.), each part of the wiring board can be uniformly heated with high precision and stability. Also, the adaptability to the change of the heating profile is improved. Further, it becomes possible to optimally adjust the amount of heat transfer by hot air and the amount of heat transfer by infrared rays and their ratio in each of the temperature raising part and soaking part in the preheating step and each part of the reflow step.

As a result, a reflow soldering apparatus capable of heating each part of the wiring board extremely uniformly and with a highly reproducible profile is realized, and a high quality wiring board can be manufactured.

In the invention according to claim 4, the atmosphere circulation means is constructed so that the amount of air blown is variable.
In addition to the above effect, it is possible to individually adjust and control the amount of hot air blown, that is, the speed of hot air on the wiring board. The adjustment range of can be further widened.

As a result, the adaptability to the constitutional state of the wiring board is further improved.

[Brief description of drawings]

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

2 is a cross-sectional view taken along the line II of FIG.

FIG. 3 is a block diagram showing a heater power control system.

FIG. 4 is a side sectional view showing a conventional infrared heating type reflow soldering device.

FIG. 5 is a side sectional view showing a conventional hot-air heating type reflow soldering device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring board 21 Heating furnace 22 Temperature raising part 23 Soaking part 24 Preheating part 25 Reflow part 26 Furnace body 27 Transfer conveyor 31 Labyrinth part 32 Labyrinth part 33 Guide plate 34 Atmosphere circulation path 36 Centrifugal blower 39 Atmosphere heating heater 40 Infrared heater 42 atmosphere temperature measurement sensor 43 surface temperature measurement sensor 52 power control section 53 power control section 54 temperature control section 55 temperature control section 56 instruction input section 57 instruction input section

Claims (4)

[Claims] 1. A reflow soldering method for heating a wiring board transported in a heating furnace with hot air and hot wires, wherein the atmosphere in the heating furnace is circulated by an atmosphere circulation means, and the circulating atmosphere is heated. And heating the wiring board with infrared rays generated from an infrared heater, and at least one of the hot air temperature blown onto the wiring board or the amount of air blown by the atmosphere circulating means. Control the amount of convective heat transfer based on the surface temperature of the infrared heater, and control the amount of radiant heat transfer based on the surface temperature of the infrared heater, the air flow rate of the atmosphere circulation means, the hot air temperature blown on the wiring board, and the surface of the infrared heater. A reflow soldering method characterized in that temperature and temperature are controlled independently of each other. 2. The power applied to the atmosphere heating heater is controlled by referring to the detection value of the hot air temperature measuring sensor to control the temperature of the hot air blown on the wiring board to a desired constant temperature, and the infrared heater 2. The reflow process according to claim 1, wherein the power applied to the infrared heater is controlled with reference to the detection value of the surface temperature measuring sensor to control the surface temperature of the infrared heater to a desired constant value. Soldering method. 3. An atmosphere circulation passage formed by partitioning the inside of the heating furnace with a partition member, an atmosphere circulation means for circulating the atmosphere in this atmosphere circulation passage, and a wiring board across the atmosphere circulation passage. A transport conveyor for transporting, an infrared heater arranged to allow circulation of the atmosphere in the vicinity of at least one surface of the wiring board transported by the transport conveyor, and the partition member of the partition member when viewed from the wiring board. A heater for atmosphere heating arranged in the atmosphere reflux path corresponding to the back side, a sensor for measuring surface temperature for detecting the surface temperature of the infrared heater, and a surface side on which the circulating atmosphere blows against the wiring board And an ambient temperature measuring sensor that is provided in the vicinity thereof to detect the hot air temperature of the atmosphere, and an instruction input unit that sets the surface temperature of the infrared heater, A power control unit that adjusts the power supplied to the infrared heater, compares the instruction value of the instruction input unit with the detection value of the surface temperature detection sensor of the infrared heater, and controls the power so that both values match. Temperature control unit for controlling the temperature of the atmosphere, an instruction input unit for setting the atmosphere temperature, a power control unit for the atmosphere heating heater for adjusting the power supplied to the atmosphere heating heater, and an instruction for the instruction input unit A temperature control unit that controls a power control unit that adjusts the electric power supplied to the atmosphere heating heater so that the values are compared with the values detected by the hot air temperature detection sensor so that the two values match. Reflow soldering equipment characterized by. 4. The reflow soldering device according to claim 3, wherein the atmosphere circulation means is configured so that the air flow rate is variable.