JPH10209629A - Reflow soldering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflow soldering device which eliminates the need to prepare a sample for temperature measurement by attaching a thermoelectric couple to a solder mounting substrate. SOLUTION: Infrared temperature sensors 61 to 64 measure the surface temperature of printed boards 7 sequentially sent to preheating zones 111 to 113 and a reflow zone 114 , from the outside of the furnace. A fuzzy control unit 21 of an automatic temperature-profile setting unit 9 automatically selects one of the zones 111 to 114 so as to change the temperature of fin heaters 41 to 44 and infrared heaters 51 to 54 in the selected zone, from the surface temperature values of the substrates measured by the infrared temperature sensors 61 to 64 , the differences from a target temperature, and thermal-capacity alternative characteristic values of the print substrates 7, in accordance with a predetermined rule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflow soldering apparatus for automatically soldering components to a printed circuit board surface.

[0002]

2. Description of the Related Art Normally, in order to obtain an optimum temperature profile for soldering, a thermocouple is fixed to a printed circuit board mounted by soldering to prepare a sample, and the heater temperature of each zone of a reflow furnace is set to a value obtained by a conventional method. The operation of setting the temperature based on experience, temporarily passing the sample through a reflow furnace, measuring the temperature, and correcting and changing the set value of the heater temperature based on the measured data was repeated several times.

Further, a system for taking temperature data from a thermocouple into a computer and changing the temperature to an optimum heater set temperature has already been devised and marketed.

[0004]

However, in the method of measuring the temperature by fixing the thermocouple to the printed circuit board by soldering, the temperature of the printed circuit board and the component lead portion can be accurately measured. This requires skill in the preparation of the device and fixing it to the part (adhesion with high-temperature solder or epoxy resin), and also tends to cause an error in the fixing method, requiring time and labor.

[0005] In addition, the operation of setting the temperature of the heater is left to the operator, and it takes much time for a person other than a skilled person. The present invention has been made in view of the above problems, and has as its object to attach a thermocouple to a mounting board by soldering the thermocouple to eliminate the need to prepare a sample for temperature measurement. An object of the present invention is to provide a reflow soldering apparatus.

[0006]

According to the first aspect of the present invention, at least each of a preheating zone for preheating a printed circuit board on which components are mounted via solder and a reflow zone for melting solder is provided. In a reflow soldering apparatus provided with a provided reflow furnace, means for setting the temperature of the heater provided for each zone to a predetermined temperature, respectively, and transport means for transporting the printed circuit board and sequentially passing through each zone, An infrared temperature sensor provided for each zone and measuring the surface temperature of the printed circuit board after passing through each zone, and a temperature profile for changing the set value of the heater temperature of each zone from the measured temperature of the infrared temperature sensor And means for creating

According to a second aspect of the present invention, in the first aspect of the present invention, the means for creating a temperature profile includes the information of the printed circuit board which is initially input and the temperature of the surface of the printed circuit board measured by the infrared temperature sensor. A correction means is provided for changing the set value of the heater temperature of each zone so that the temperature profile created in (1) matches the temperature profile input as the target value.

According to a third aspect of the present invention, in the second aspect of the present invention, the correction means comprises fuzzy control means for estimating a heater temperature correction value by fuzzy inference based on a rule table in which a correction width is ruled. It is characterized by. According to a fourth aspect of the present invention, in the first aspect of the present invention, the conveying means is configured by a conveyor comprising parallel conveyor portions so that the width of the conveyor can be varied according to the width of the printed circuit board, and the infrared temperature sensors corresponding to each zone. Is set near the conveyor section which is fixed when the conveyor width is variable.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the measurement temperature from when the printed circuit board starts passing through the measurement range of the infrared temperature sensor until the end thereof is sampled, and the maximum value among the sampled measurement temperatures is obtained. Alternatively, an average value near the maximum value is adopted as the surface temperature of the printed circuit board. According to a sixth aspect of the present invention, in the fifth aspect of the present invention, it is determined that the printed circuit board is passing through the measurement range of the infrared temperature sensor, and that the measured temperature of the infrared temperature sensor exceeds a preset temperature level. It is characterized by determining by detecting.

According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the fact that the printed circuit board is passing through the measurement range of the infrared temperature sensor indicates that the detection signal from the board detection sensor provided at the entrance of the reflow furnace. From the input time point, the elapsed time required from the arrival at the measurement range of the infrared temperature sensor to the end of the passage is calculated or measured from the transport speed of the transport means and determined.

According to an eighth aspect of the present invention, in the first aspect of the invention, the infrared temperature sensor measures the surface temperature of a printed circuit board in the furnace from outside the furnace through an opening window provided in the furnace body of the reflow furnace. The opening of the opening window is characterized by being sealed and closed by a filter that transmits infrared rays. According to a ninth aspect of the present invention, in the second or third aspect, the means for creating a temperature profile sets the heater temperature so as to be lower than the input target temperature and reduces the surface temperature of the printed circuit board. Under the same conditions as the initial temperature measurement process to be measured and the heater temperature conditions during the initial temperature measurement process, measure the surface temperature of the printed circuit board by making the transport speed of the printed circuit board slower than the transport speed during the initial temperature measurement process. The second temperature measurement process, the temperature difference between the printed circuit board surface temperature measured in the second temperature measurement process and the printed circuit board surface temperature measured in the first temperature measurement process, and the infrared temperature sensor used by the infrared temperature sensor in the first temperature measurement process Based on the time difference between the time when the temperature of the printed circuit board was measured and the time when the infrared temperature sensor measured the surface temperature of the printed circuit board in the second temperature measurement process. The heat capacity substitute characteristic value is obtained, and the heater temperature correction value is estimated from the difference between the target temperature and the printed circuit board surface temperature measured in the initial temperature measurement process and the heat capacity substitute characteristic value to change the heater temperature set value. A value estimation process and a third temperature measurement process for measuring the surface temperature of the printed circuit board at the same transport speed as in the initial temperature measurement process are set, and the surface temperature of the printed circuit board and the target temperature measured in the third temperature measurement process are set. If the difference is within a preset allowable range, the changed heater temperature set value is registered,
If the temperature is outside the allowable range, the correction value estimation process and the third temperature measurement process are repeated until the difference between the surface temperature of the printed circuit board measured in the third temperature measurement process and the target temperature falls within the allowable range. And

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an entire apparatus according to an embodiment of the present invention.
1 ₁ to 11 _3, the reflow zone 11 _4, and each zone of the cooling flow zone 11 _5, is constructed and a conveyor 2. Each zone 11 ₁ to 11 ₅ is adapted to providing agitation fan 3 ₁ to 3 ₅ at the ceiling portion of the upper conveyor 2, to agitate the air in the zone 11 ₁ to 11 ₅ of each.

[0013] preheating zone 11 ₁ to 11 ₃ fin heater 4 ₁ to 4 ₃ to heat the atmosphere in the zone
And at the upper and lower positions of the conveyor 2,
Is attached a temperature sensor (not shown) is provided an infrared heater 5 ₁ to 5 ₃ to heat the printed circuit board 7 in the far infrared,
Also the outside of the furnace in correspondence with the zone 11 ₁ to 11 _3, provided an infrared temperature sensor 6 ₁ to 6 ₃ to measure the surface temperature of the printed circuit board 7 on the conveyor 2 which passes through the zone 11 ₁ to 11 _3, Further, temperature sensors 8 _{1 to} 8 ₃ made of thermocouples for detecting the ambient temperature in the preheating zones 11 _{1 to} 11 ₃ are provided for each of the preheating zones 11 _{1 to} 11 _3.
Preheating the printed circuit board 7 mounted with the component via the solder in ₁ to 11 _3.

[0014] The reflow zone 11 ₄ preheating zone 11 ₁
To 11 ₃ similarly to the fin heater 4 _4, infrared heaters 5
₄ and provided with a temperature sensor 8 _4, the zone 11
The infrared temperature sensor 6 ₄ for detecting the surface temperature of the printed circuit board 7 on the conveyor 2 passing ₄ is provided with the furnace,
The reflow zone 11 ₄ in the printed circuit board 7 is melted solder between the mounted components.

The cooling zone _{11. 5} is a zone for connecting the mounted and the printed circuit board 7 is cooled component soldering a printed board 7 and the molten solder by supplying air by agitation fan _35. Conveyor 2, the printed circuit board 7 to each zone 11 ₁ to 11 ₅ of the reflow furnace 1 are sequentially conveyed at a predetermined speed, sequentially pass through the respective zones 11 ₁ to 11 ₅ a printed board 7.

The infrared temperature sensor ₆₁ to 6 provided in each preheating zone 11 ₁ to 11 _3, the reflow zone 11 ₄
The detection output of ₄ is received by the automatic temperature profile setting unit 9, also measuring the output of the temperature sensor 8 ₁ to 8 ₄ is adapted to be received by the control unit 10. Automatic temperature profile setting unit 9, an A / D converter 20 to the detection output A / D conversion of the measurement output of the infrared temperature sensor 6 ₁ to 6 _4, the fuzzy control unit 21, a CCU 22,
Enter PCB conditions such as PCB material, size, thickness, number of layers and density of components mounted on the PCB,
Set target temperature profile, display and analyze measurement results,
It has an application program for displaying the recommended heater temperature, executing the setting change, and storing the data, and has a processing device 23 which is a personal computer executed when the device is operated. The fuzzy control unit 21 which zones 11 ₁ to 11 ₄ of the heater 4 from the difference and the heat capacity alternative characteristic values of the substrate and the measured temperature
It has the function of automatically determined in accordance with ₁ to 4 ₄ and 5 ₁ to 5 ₄ fixed rule set is whether the temperature should be changes.

Meanwhile the control unit 10, the temperature sensor 8 ₁ to 8
_Fourth detection heater so that the temperature reaches the set value of the ambient temperature 4 ₁ to 4 to control the _fourth power, also infrared heaters 5 ₁ to 5 so that the detected temperature of the temperature sensor reaches the set value of the heater temperature annexed PID unit 3 that controls energization of ₄ and controls the ambient temperature and heater temperature of the zone
0, a D / A converter 31 for generating a control output of the rotation speed of the stirring fans 3 _{1 to} 3 ₄ and a control output of the transport speed of the conveyor 2, a control monitor of the entire system 10, and an automatic temperature profile through the bus. A CPU 32 for transmitting and receiving data to and from the setting unit 9; an input unit 33 for inputting and setting various data such as a heater temperature setting, a conveyor speed setting, a stirring fan speed setting, and a substrate dimension input.
And a CCU 34 for exchanging data between the input unit 33 and the CPU 32.

Here, the infrared temperature sensor 6 of the present embodiment
_{1-6 4} is attached to the upper portion of the outside reflow furnace 1,
Since protection against heat and airtightness are required in consideration of the case where nitrogen gas is introduced into the furnace and used as N ₂ reflow, the infrared temperature sensor 6 is cooled by the cooling fan 46 as shown in FIG. While cooling, the opening window 1b of the furnace body 1a of the reflow furnace 1 facing the infrared temperature sensor 6 is hermetically closed with a filter 40 made of barium fluoride that transmits infrared rays. Reference numeral 41 denotes a packing for maintaining airtightness, and reference numeral 42 denotes a frame for fastening and fixing the filter 40 in the opening window 1b. In the furnace, flux mist for soldering is generated and adheres to the furnace inner surface of the filter 40. In order to prevent this adhesion, in the present embodiment, the pipe 43 is attached so that one end is connected to the inside of the furnace of the opening window 1b, and air or N ₂ gas is introduced into the pipe 43 from outside the furnace. The flux is prevented from entering the furnace inner surface of the filter 40 by blowing of air or N ₂ . 44 has one end communicates with the pipe 43, the other end is led outside through the valve 45, air and N ₂
Is a communication pipe for injecting into the pipe 43.

By the way, in general, the reflow soldering apparatus has to correspond to various sizes of the mounting printed circuit board 7, so that the width of the conveyor 2 can be changed. In other words, the conveyor 2 is made up of parallel conveyor sections, and both sides of the printed circuit board are placed on the conveyor sections on both sides and moved. The one conveyor unit is used as a reference conveyor unit, and the other conveyor unit is allowed to approach and separate from the reference conveyor unit so that the width of the conveyor 2 can be changed. Therefore, in the present embodiment, as shown in FIG. 3, the position of the temperature measurement range X (about φ30) of the infrared temperature sensor 6 is set to the reference side conveyor portion 2a.
This is the position of the end portion of the zone installed for measuring the surface temperature of the printed circuit board 7 approaching the side and passing through the zone.

Since the printed circuit board 7 has a notch 7a or a cutout at an arbitrary position as shown in FIG. 4A, the cutout 7a or the cutout may pass through the temperature measurement range X of the infrared temperature sensor 6. There is. Even in this case, as a method of obtaining a reproducible value as the substrate temperature, when the printed circuit board 7 passes under the infrared temperature sensor 6, the general measured value changes as shown in FIG. The value or the average value near the maximum value is adopted as the substrate temperature.

That is, the processing unit 23 of the automatic temperature profile setting unit 9 converts the measured temperature data captured by the A / D converter 20 into measured values until the printed circuit board 7 arrives below the infrared temperature sensor 6 and finishes passing therethrough. Is sampled, and a maximum value or an average value around the maximum value is obtained as described above, and is used as a measured temperature. The timing at which the printed circuit board 7 arrives below the infrared temperature sensor 6 and finishes passing is detected as follows. That is, when the printed circuit board 7 does not normally come under the infrared temperature sensor 7, the emissivity is low, and the apparent value measured by the infrared temperature sensor 7 is low. In the embodiment, for example, as shown in FIG.
7 and the infrared temperature sensor 6 measures the surface temperature of the aluminum plate 47 when the printed circuit board 7 does not come down, and the measured temperature rises when the printed circuit board 7 passes. As shown in ()), while the temperature higher than the preset pass determination temperature level La is being measured, it is determined that the substrate is passing.

FIG. 6 shows an example of a method for determining that the vehicle is passing.
As shown in the figure, for example, a photoelectric detection sensor 48 for detecting a substrate is provided at the entrance of the reflow furnace 1 to detect the speed of the conveyor 2 and rotation by a slit plate provided on a drive shaft (not shown) of the conveyor 2. A method of using a pulse to determine the timing at which the printed circuit board 6 is passing below the infrared temperature sensor 6 may be employed.

Next, the operation of automatically creating a temperature profile, which is a feature of the present invention, will be described with reference to the flowchart of FIG. First, when operating the reflow soldering apparatus, input of a target temperature profile of the surface temperature of the printed circuit board 7 and input of board information (board dimensions, board thickness, layer thickness) using the processing device 23 of the automatic temperature profile setting section 9. (Number, mounting amount of mounted components, etc.) and the speed of the conveyor 2 are input. Based on the input data, the processing device 23 sets initial heater setting conditions based on a database stored in a storage device (not shown) in advance.

According to the initial heater setting conditions, each zone 1
1 ₁ to 11 ₄ of the ambient temperature, the infrared heater 4 ₁ to 4
₄ is set, and the control unit 1 is set based on the set temperature.
PID unit 30 0 performs control of energization of the infrared heaters 5 ₁ to 5 ₄ to measure the temperature of the temperature sensor disposed in an infrared heater 5 ₁ to 5 ₄ (not shown) is the set temperature, the temperature measurement temperature sensor 8 ₁ to 8 ₄ performs control of energization of the fin heater 4 ₁ to 4 ₄ so that the set temperature. The outputs through the D / A converter 31 a control output for operating the conveyor 2 at the desired speed to the drive motor of the conveyor 2 (not shown) by CPU 32, the predetermined rotational speed stirring fan 3 ₁ to 3 ₅ stirring fan 3 ₁ to 3 ₅ a control output for in rotating
To a drive motor (not shown).

When it is confirmed from the measured temperatures of the temperature sensors 8 _{1 to} 8 ₄ through the PID unit 30 that the ambient temperature of each of the zones 11 _{1 to} 11 ₄ has been stabilized, the processing device 23 sets the infrared temperature sensor 4 measure temperature by ₁ to 4 _4. That at the conveyor 2 in each zone 11 ₁ to 11 ₄ to measure the surface temperature of the printed circuit board 7 which is conveyed by a conveyor 2 (first temperature measurement).

In this case, the first heater setting conditions are set so that the surface temperature of the printed circuit board 7 is lower than the target temperature in advance. FIG. 7 shows the preheating zone 11.
And the surface temperature of the printed circuit board 7 is moving at ₁ shows the timing of the infrared temperature sensor 4 ₁ of the surface temperature measurement, it is the transition of the surface temperature of the printed circuit board 7 based on the target temperature profile, Mataro Shows the transition of the surface temperature of the printed circuit board 7 at the time of the initial temperature measurement. In the figure, a shows the input target temperature, and b shows the temperature measured by the initial temperature measurement.

Next, in order to estimate the heat capacity of the substrate, the speed of the conveyor 2 is set to a side lower than the initial set value, and the surface temperature of the printed circuit board 7 is measured under the initial heater setting conditions (2). Second temperature measurement). Ha Figure 7 shows the transition of the surface temperature of at the printed circuit board 7 to the preheating zone 11 ₁ during the second temperature measurement. In the case of this second temperature measurement,
After the transfer of the printed circuit board 7 is started, each zone 11
In ₁ to 11 _4, the infrared temperature sensor 4 ₁ to 4 ₄
The timing for measuring the surface temperature of the printed circuit board 7 passing below is later in the second time than in the first time (the temperature is measured with a delay of Δt in FIG. 7 and c in the figure).
Indicates the temperature measured in the second temperature measurement). That because the transit time in each zone 11 ₁ to 11 ₄ becomes longer,
Higher temperature measurements are obtained.

The processing unit 23 obtains the temperature ΔT that has risen during the measurement timing difference Δt seconds from the first measurement result and the second measurement result, and uses the ΔT as a denominator, the difference Δt as a numerator, and the printed circuit board 7. asking whether such many seconds to raise 1 ° C., multiplied by a predetermined constant K related heating capacity of each zone 11 ₁ to 11 ₄ in the obtained value [K · (Δt / Δ
T)] is adopted as an indirect substitute characteristic value relating to the heat capacity of the printed circuit board 7.

Next, the difference Δ between the first measured temperature b and the target temperature a
According D and the K · (Δt / ΔT) value based on the fuzzy inference, as shown in the fuzzy control unit 21 in FIG. 8 based on rules, and the ambient set temperature in each zone 11 ₁ to 11 _4, the infrared heaters 5 ₁ to make a change of 5 ₄ set temperature value. That is, a process of correcting and changing the set value is performed so that the temperature profile obtained by the actual measurement matches the input target temperature profile.

Here, the fuzzy control unit 21 calculates ΔD
And a rule table in which an appropriate correction width of a predetermined temperature is ruled for K · (Δt / ΔT). That is, when the temperature difference ΔD is large and the substitute characteristic value is small, correction is made so that each set temperature is raised slightly. When the temperature difference ΔD is small and the substitute characteristic value is large, correction is made so that each set temperature is raised greatly. When the difference ΔD is small and the substitute characteristic value is small, there is provided a rule table that is made into a rule so that correction is made to slightly raise the predetermined temperature, and the fuzzy control unit 21 estimates a correction value based on this rule table, and the ambient temperature setting value in the respective zones 11 ₁ to 11 ₄ on the basis of the correction value is performed to change the set temperature of the infrared heater 5 ₁ to 5 _4.

[0031] Then with PID unit 30 controls the energization of the fin heater 4 ₁ to 4 ₄ so that the set value temperature detected by the temperature sensor 8 ₁ to 8 ₄ is changed based on the change of the set value , controls the energization of the infrared heaters 5 ₁ to 5 _4, as the temperature detected by the temperature sensors attached becomes the set value. When the controller 10 confirms that the ambient temperature and the heater temperature are stabilized, the processing device 23 performs a third temperature measurement based on the stability confirmation information, and obtains a difference ΔD between the target temperature and the measured temperature. if within the allowable range this difference ΔD is set in advance, the changes were set temperature value is registered as a data, followed by the zones 11 ₁ to 1 at the time of reflow soldering of the printed circuit board 7 to be performed
1 ₄ and the ambient temperature, the temperature of the infrared heater 5 ₁ to 5 ₄ are set as the set value in the PID unit 30 based on the registration data, to attach a temperature sensor 8 ₁ to 8 ₄ and an infrared heater 5 ₁ to 5 ₄ PID unit 10 so that the detected temperature of the temperature sensor becomes equal to the set value of the respective controls the energization of the fin heater 4 ₁ to 4 ₄ and an infrared heater 5 ₁ to 5 _4, the surface temperature of the printed circuit board 7 to the target temperature By controlling the ambient temperature and the heater temperature so as to approach, good reflow soldering is enabled.

If the difference ΔD is out of the allowable range, the step of changing the heater temperature set value based on the immediately preceding fuzzy inference is repeated to finally obtain the optimum set temperature value.

[0033]

According to the first aspect of the present invention, there is provided a reflow furnace provided with at least a preheating zone for preheating a printed circuit board on which components are mounted via solder and a reflow zone for melting solder, and a reflow furnace provided for each zone. In a reflow soldering apparatus provided with means for setting the temperature of each of the heaters to a predetermined temperature, and transport means for transporting the printed circuit board and sequentially passing through each zone, provided for each zone,
Since there are provided an infrared temperature sensor for measuring the surface temperature of the printed circuit board after passing through each zone, and means for creating a temperature profile for changing the set value of the heater temperature of each zone from the measured temperature of the infrared temperature sensor. It is necessary to prepare a sample for temperature measurement by attaching a thermocouple to a printed circuit board as in the past, and it is necessary to repeatedly measure the surface temperature of the printed circuit board with a thermocouple and change the heater temperature manually. Therefore, there is an effect that a temperature profile for automatically obtaining an optimal heater temperature set value can be obtained in a short time and automatically.

According to a second aspect of the present invention, in the first aspect of the present invention, the means for creating the temperature profile includes information on the printed circuit board initially input and the temperature of the printed circuit board surface measured by the infrared temperature sensor. In order to make the temperature profile created in (1) match the temperature profile entered as the target value, the temperature profile is provided with correction means for changing the set value of the heater temperature of each zone. There is an effect that the correction can be changed to the optimal set value.

According to a third aspect of the present invention, in the second aspect of the present invention, the correction means comprises fuzzy control means for estimating a heater temperature correction value by fuzzy inference based on a rule table in which a correction width is ruled. Thus, the heater temperature can be corrected to an appropriate value, and the surface temperature of the printed circuit board can be brought close to the target temperature with high accuracy.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the conveying means is constituted by a conveyor comprising parallel conveyor portions so that the width of the conveyor can be varied according to the width of the printed circuit board. Since the measurement range of the infrared temperature sensor is set near the conveyor part which is fixed when the conveyor width is variable, it is not necessary to change the measurement position of the infrared temperature sensor even by changing the conveyor width. There is an effect that a printed circuit board having a size can be accommodated.

According to a fifth aspect of the present invention, in the first aspect of the present invention, a measurement temperature is sampled from the time when the printed circuit board starts passing through the measurement range of the infrared temperature sensor until the end thereof, and the maximum value among the sampled measurement temperatures is obtained. Or, since the average value near the maximum value is adopted as the surface temperature of the printed circuit board, even if the printed circuit board has cutouts, holes, etc., and that part passes through the measurement range of the infrared temperature sensor, it is not affected There is an effect that the temperature of the substrate surface can be measured.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, it is determined that the printed circuit board is passing through the measurement range of the infrared temperature sensor when the measured temperature of the infrared temperature sensor exceeds a preset temperature level. Since the determination is made by detecting that the temperature is detected, there is an effect that the temperature detection timing by the infrared temperature sensor can be reliably obtained.

According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the fact that the printed board is passing through the measurement range of the infrared temperature sensor is determined by detecting the detection signal from the board detection sensor provided at the entrance of the reflow furnace. From the input time, the elapsed time required from reaching the measurement range of the infrared temperature sensor to the end of the passage is calculated or measured from the transport speed of the transport means, and the temperature detection timing by the infrared temperature sensor is reliably taken. There is an effect that can be.

According to an eighth aspect of the present invention, in the first aspect, the infrared temperature sensor measures the surface temperature of the printed circuit board in the furnace from outside the furnace through an opening window provided in the furnace body of the reflow furnace. Since the opening of the opening window is sealed and closed by a filter that transmits infrared light, the surface temperature of the printed circuit board can be measured by an infrared temperature sensor without being affected by the furnace temperature. Even if there is, there is an effect that the airtightness in the furnace can be maintained.

According to a ninth aspect of the present invention, in the second or third aspect of the present invention, the means for creating the temperature profile sets the heater temperature so that the temperature is lower than the input target temperature, and Under the same conditions as the initial temperature measurement process for measuring the surface temperature and the heater temperature conditions during the initial temperature measurement process, make the transport speed of the printed circuit board slower than the transport speed during the initial temperature measurement process to reduce the surface temperature of the printed circuit board. The temperature difference between the printed circuit board surface temperature measured in the second temperature measurement process and the printed circuit board surface temperature measured in the first temperature measurement process, and the infrared temperature sensor in the first temperature measurement process Based on the time difference between the time when the surface temperature of the printed circuit board was measured and the time when the infrared temperature sensor measured the surface temperature of the printed circuit board in the second temperature measurement process. Determine the heat capacity substitute characteristic value of the printed circuit board, change the heater temperature set value by estimating the heater temperature correction value from the difference between the target temperature and the printed circuit board surface temperature measured in the initial temperature measurement process and the above heat capacity substitute characteristic value A correction value estimating process to be performed and a third temperature measuring process of measuring the surface temperature of the printed circuit board at the same transport speed as the initial temperature measuring process are set, and the surface temperature of the printed circuit board measured in the third temperature measuring process and If the difference from the target temperature is within a preset allowable range, the set value of the changed heater temperature is registered. If the difference is outside the allowable range, the correction value estimation process and the third temperature measurement process are performed for the third time. It repeats until the difference between the surface temperature of the printed circuit board measured in the temperature measurement process and the target temperature falls within the allowable range, so that the set temperature can be properly corrected and the temperature of the printed circuit board surface can be adjusted to the target temperature. There is an effect that it is possible to approach accurately on.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of the entire apparatus of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the above.

FIG. 3 is an explanatory diagram of a positional relationship between the infrared temperature sensor and the conveyor according to the first embodiment.

FIG. 4 is an explanatory diagram of temperature measurement by the infrared temperature sensor according to the first embodiment;

FIG. 5 is an explanatory diagram of a method for detecting that the printed circuit board passes through the measurement range of the infrared temperature sensor.

FIG. 6 is an explanatory diagram of another method for detecting that the printed circuit board passes the measurement range of the infrared temperature sensor.

FIG. 7 is a flowchart for explaining automatic temperature profile creation according to the first embodiment;

FIG. 8 is an explanatory diagram of a temperature measuring process according to the embodiment.

FIG. 9 is an explanatory diagram of the operation of the fuzzy control unit of the above.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Reflow furnace 2 Conveyor 3 ₁ ... Stirrer fan 4 ₁ ... Fin heater 5 ₁ ... Infrared heater 6 ₁ ... Infrared temperature sensor 7 Printed circuit board 8 ₁ ... Temperature sensor 9 Automatic temperature profile setting part 10 Control part 11 ₁ ... Zone 20 A / D converter 21 Fuzzy control unit 22 CCU 23 Processing unit 30 PID unit 31 D / A converter 32 CPU 33 Input unit 34 CCU

Claims (9)

[Claims] The temperature of a reflow furnace provided with at least a preheating zone for preheating a printed circuit board on which components are mounted via solder and a reflow zone for melting solder, and the temperature of a heater provided for each zone, respectively. In a reflow soldering apparatus provided with a means for setting a predetermined temperature and a transport means for transporting a printed circuit board and sequentially passing through each zone, the reflow soldering apparatus is provided corresponding to each zone, and the printed circuit board after passing through each zone is provided. A reflow soldering apparatus, comprising: an infrared temperature sensor for measuring a surface temperature; and means for creating a temperature profile for changing a set value of a heater temperature in each zone from a temperature measured by the infrared temperature sensor. 2. A means for creating a temperature profile includes, as target values, information on a printed circuit board initially input and a temperature profile created based on the temperature of the printed circuit board surface measured by an infrared temperature sensor. 2. The reflow soldering apparatus according to claim 1, further comprising a correction unit for changing a set value of a heater temperature of each zone so as to match the set temperature profile. 3. The reflow soldering device according to claim 2, wherein said correction means comprises fuzzy control means for estimating a correction value of the heater temperature by fuzzy inference based on a rule table in which the correction width is ruled. apparatus. 4. A conveyor comprising parallel conveyor sections so that the conveyor width can be varied according to the width of the printed circuit board, and the measuring range of the infrared temperature sensor corresponding to each zone is adjusted by changing the conveyor width. 2. The reflow soldering apparatus according to claim 1, wherein the reflow soldering apparatus is set near a conveyor part which is sometimes fixed. 5. The method according to claim 1, further comprising: sampling a measurement temperature from a time when the printed circuit board starts passing through the measurement range of the infrared temperature sensor until the end of the measurement; The reflow soldering apparatus according to claim 1, wherein the reflow soldering apparatus is employed as a temperature. 6. A method for determining whether a printed circuit board is passing through a measurement range of an infrared temperature sensor by detecting that a measurement temperature of the infrared temperature sensor exceeds a preset temperature level. The reflow soldering apparatus according to claim 5, wherein 7. The fact that the printed circuit board is passing through the measurement range of the infrared temperature sensor is determined to be within the measurement range of the infrared temperature sensor from the time when a detection signal is input from the substrate detection sensor provided at the entrance of the reflow furnace. 6. The reflow soldering apparatus according to claim 5, wherein an elapsed time required from the arrival to the end of the passage is calculated or measured from the transport speed of the transport means. 8. An infrared temperature sensor for measuring the surface temperature of a printed circuit board in the furnace from outside the furnace through an opening window provided in the furnace body of the reflow furnace, and the opening of the opening window transmits infrared light. 2. The reflow soldering apparatus according to claim 1, wherein the apparatus is sealed and closed by a filter. 9. An initial temperature measuring step of setting a heater temperature so as to be lower than an input target temperature and measuring a surface temperature of a printed circuit board; A second temperature measurement process in which the transfer speed of the printed circuit board is made slower than the transfer speed in the initial temperature measurement process to measure the surface temperature of the printed circuit board under the same conditions as the heater temperature conditions during the process, and a second temperature measurement The temperature difference between the printed circuit board surface temperature measured in the process and the printed circuit board surface temperature measured in the first temperature measurement process, and the time when the infrared temperature sensor measures the surface temperature of the printed circuit board in the first temperature measurement process and the second temperature measurement process The heat capacity substitute characteristic value of the printed circuit board is obtained based on the time difference from the time when the infrared temperature sensor measures the surface temperature of the printed circuit board, and the target temperature and A correction value estimation process of estimating a heater temperature correction value from the difference between the printed circuit board surface temperature measured in the first temperature measurement process and the heat capacity substitute characteristic value and changing the heater temperature set value, and a first temperature measurement process. A third temperature measurement process for measuring the surface temperature of the printed circuit board at the same transport speed is set, and a difference between the surface temperature of the printed circuit board measured in the third temperature measurement process and the target temperature is set in advance. , The set value of the changed heater temperature is registered. If the set value is out of the allowable range, the correction value estimation process and the third temperature measurement process are performed in accordance with the surface temperature of the printed circuit board measured in the third temperature measurement process. 4. The reflow soldering apparatus according to claim 2, wherein the process is repeated until the difference from the target temperature falls within an allowable range.