JPH102801A - Temperature detection method of the object to be heated in infrared heating furnace - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To detect a temperature of an object to be heated in an infrared heating furnace by quantitatively and accurately detecting the temperature only by calculation. SOLUTION: When detecting the temperature of an object to be heated in a heating furnace having an infrared heater by numerical analysis, the wavelength range of infrared rays is divided into a plurality of ranges, and the object to be heated is divided for each of the divided wavelength ranges. Calculate the balance between the amount of radiant heat received from the heater and the amount of radiant heat radiated to the surroundings, and add these to calculate the net radiant heat received by the heated body in the furnace,
Using this as a boundary condition, a thermal analysis of the object to be heated is performed to detect the temperature of the object to be heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for detecting the temperature of an object to be heated in an infrared heating furnace.

[0002]

2. Description of the Related Art Infrared heating is capable of directly and instantaneously heating an object to be heated, and is therefore attracting attention as a high-value-added heating method that is efficient in a wide range of fields such as industrial, medical, and food processing. In the field of electronic devices, in a mounting step of soldering electronic components onto a printed board, a heating furnace called an infrared reflow furnace of a method of heating with an infrared heater to melt the solder is used.

However, because the infrared heating is not suitable for local heating and the infrared absorption characteristics are different due to the difference in the material of the object to be heated, the printed board is uniformly heated and the solder joints are appropriately heated. It is difficult to set conditions such as the temperature of the infrared heater and the heating time so that the temperature becomes appropriate.

[0004] For this reason, the setting of the heating conditions for a new printed board is performed by actually measuring the temperature of the printed wiring board using a thermoelectric body or the like, and setting conditions such as the temperature and heating time of the infrared heater based on the experience and intuition of the operator. Repeat several times,
The solder joint was set to the target temperature. However, such a method for setting the heating conditions requires a lot of time for setting and is extremely poor in work quality, and is even more difficult when an inexperienced operator performs these settings.

[0005] For this reason, the temperature distribution of the object to be heated in the infrared heating furnace is predicted by numerical analysis, and the prediction is used in part for setting heating conditions of the infrared heating furnace. However, in the conventional method, although the matching of the wavelength distribution of the radiant energy of the infrared heater and the wavelength distribution of the absorptance of the object to be heated greatly affects the degree of temperature rise of the object to be heated, it is ignored. The emissivity and the absorptance are constant without depending on the wavelength, and are calculated using the average value (calculated as a gray body).

Further, the ratio (view factor) of the energy reaching the object to be heated from the infrared heater varies depending on the state of the heating furnace, but this cannot be taken into account. The object to be heated is a belt
When moving in a furnace on a conveyor, etc., the view factor changes with time, but radiation is an important factor in determining quantitative analysis accuracy, such as calculating this constant for ease of calculation. The calculations were simplified.

[0007]

For this reason, the result of thermal analysis of a printed board in an infrared reflow furnace using the conventional radiation calculation method is compared with the actual temperature distribution of the printed board in the reflow furnace and its time change. Then, there was a problem that the quantitative accuracy was lacking, and it was difficult to determine the heating conditions of the printed board such as the temperature of the infrared heater in the reflow furnace and the heating time (conveyor speed) based on only the analysis results. .

The present invention has been made in view of such circumstances, and provides a method for accurately detecting the temperature distribution of a printed wiring board in an infrared reflow furnace and its time change (temperature profile) by numerical analysis. To provide.

[0009]

SUMMARY OF THE INVENTION The present invention divides an infrared wavelength range into a plurality of ranges when detecting the temperature of an object to be heated in a heating furnace having an infrared heater by numerical analysis. For each of the wavelength ranges that have been calculated, calculate the balance between the amount of radiant heat received by the object to be heated from the heater and the amount of radiant heat radiated to the surroundings, and add these to calculate the net amount of radiated heat received by the object to be heated in the furnace, An object of the present invention is to provide a method for detecting a temperature of a heated object in an infrared heating furnace, wherein the temperature of the heated object is detected by performing a thermal analysis of the heated object using this as a boundary condition.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a view factor, which is a value indicating a ratio of radiation energy radiated from an infrared heater in an infrared heating furnace to a heated object, is referred to as a furnace coefficient when the heated object is placed on a conveyor or the like. If the position changes relative to the infrared heater due to movement within the interior, it is calculated for each time step (time increment) of the unsteady analysis or for each of a plurality of time steps. Calculate the amount of radiant heat received by the body, calculate the balance between this and the amount of radiant heat radiated by the heated object itself, and analyze the heat conduction of the heated object using the net amount of radiated heat received by the heated object as a boundary condition, The temperature distribution of the object to be heated and its time change are known.

In calculating the amount of radiant heat received by the object to be heated from the infrared heater and the amount of radiant heat radiated to the surroundings of the object itself, the wavelength distribution, emissivity, and absorptance of the radiant energy of the infrared heater and the object to be heated are calculated. Is divided into a plurality of wavelength distributions in the infrared wavelength range, the balance of the amount of heat radiated to the object to be heated in each of the divided wavelength ranges is calculated, and finally, the balance in these divided wavelength ranges is added.

In order to further improve the accuracy of the analysis result, in addition to the view factor between the infrared heater and the object to be heated, the view factor between the inner wall of the furnace and the object to be heated is calculated and used. The amount of radiant heat received by the object to be heated from the furnace inner wall surface may be calculated and added to the balance calculation.

Further, a view factor which is reflected from the infrared heater on the inner wall surface of the furnace and reaches the object to be heated is calculated, and a radiation heat amount which is reflected from the infrared heater on the inner wall surface of the furnace and reaches the object to be heated is calculated. , The accurate amount of radiation heat received by the object to be heated can be calculated.

In the radiation calculation relating to the inner wall of the furnace, the wavelength distribution of the radiation energy and the wavelength distribution of the emissivity, absorptivity, and reflectance of the infrared heater, the inner wall of the furnace, and the object to be heated are also obtained. Is divided into a plurality of parts in the infrared wavelength range, the balance of the amount of radiation heat to the heated body in each of the divided wavelength ranges is calculated, and finally, the balance in these divided wavelength ranges is added up, thereby obtaining the heated body. May calculate the net radiant heat received in the furnace.

Hereinafter, a case where these calculations are performed using a personal computer will be described in detail. here,
As shown in FIG. 1, each heater JHEAT, IH
It is assumed that EATs are arranged in the X direction, in which the object to be heated, that is, the printed circuit board PCB, moves in the X direction from the furnace inlet (X = 0) to the outlet.

An outline of the calculation procedure will be described with reference to the flowchart of FIG. First, a non-time-series (constant throughout the time step) view factor is calculated, and other non-time-series values, that is, the radiant energy of the heater and the radiant energy of the peripheral wall surface of the furnace are calculated (steps S1 to S3).

Next, the calculation for each time step is started. At the beginning of each time step, a time-series view factor (which changes with each time step) is calculated (step S4). Next, the calculation element calculates the energy directly received from the heater and the surrounding wall surface in the furnace, and calculates the energy reflected on the surrounding wall surface from the heater and received by the calculation element (steps S5 and S6). Next, after calculating the energy that the calculation element loses due to radiation, the energy balance of the calculation element is calculated (steps S7 to S9).

When the above calculation is completed for all the calculation elements (step S10), the heat quantity thus calculated is used as a radiation boundary condition that each calculation element receives, and a heat conduction analysis of the printed board is performed at the end of this time step (step S10). Step S11). Next, this time step is repeatedly executed while the printed board advances from the entrance to the exit of the furnace, and the calculation is completed (step S12).

Next, steps S1 to S10 in FIG.
Will be described with reference to the flowcharts shown in FIGS. First, calculation of a view factor that is not a time series shown in FIG. 3 is performed. The areas of the heater and the inner wall of the furnace are calculated in advance. AHEAT = LHEAT * WHEAT AWALL = 2.0 * (LWALL * WWALL + LWALL * HWALL + WW
ALL * HWALL)-8.0 * AHEAT

Here, AHEAT: area of heater LHEAT: length of heater WHEAT: width of heater AWALL: area of furnace inner wall LWALL: length of furnace inner wall WWALL: width of furnace inner wall HWALL: width of furnace inner wall Height.

Then, the calculation regarding the view factor which is not a time series is performed in the following manner. (1) Calculation of heater X coordinate HPOS (IHEAT) = LPRE + (IHEAT-1) * (LHEAT + LBET) +
LHEAT * 0.5 Where, IHEAT: IHEAT-th heater from entrance HPOS (IHEAT): X coordinate of the center of IHEAT (entrance X = 0) LPRE: Distance from entrance to front end of first heater LBET: Distance between heater and heater The distance between them.

(2) Calculation of positional relationship between heaters HPOS1 (IHEAT, JHEAT) = (IHEAT-1) * (LHEAT + LBET) +
LHEAT * 0.5- (JHEAT-1) * (LHEAT + LBET) HPOS2 (IHEAT, JHEAT) = (IHEAT-1) * (LHEAT + LBET) +
LHEAT * 0.5- (JHEAT-1) * (LHEAT + LBET) where, HPOS1 (IHEAT, JHEAT): Distance in the X direction from the center point of IHEAT to the rear end of JHEAT HPOS2 (IHEAT, JHEAT): Center of IHEAT The distance in the X direction from the point to the front end of JHEAT. JHEAT: Upper heater (1-4) IHEAT: Lower heater (1-4).

(3) Calculation of view factor between heaters SFHH (IHEAT, JHEAT) = 2.0 * (SFBASE (DISTZ * 2.0, HPO
S1 (IHEAT, JHEAT), WHEAT / 2.0)-SFBASE (DISTZ * 2.0,
HPOS2 (IHEAT, JHEAT), WHEAT / 2.0)) The function SFBASE (A, B, C) is set as follows. SFBASE (A, B, C) = ((B / (A ² + B ² ) ^0.5 ) * sin ^-1 (C / (A ² + B ² + C ² )
^0.5 ) + (C / ((A ² + C ² ) ^0.5 ) * sin ^-1 (B / (A ² + B ² + C ² ) ^0.5 ) / 2π

(Equation 1)

(SFHH (1) = SFHH (4), SFHH (2) = SFHH (3)) where, SFHH (IHEAT, JHEAT): a form factor from JHEAT to IHEAT SFHH (JHEAT): facing from JHEAT Form factor for all heaters DISTZ: This is the vertical distance between the heater and the PCB (conveyor center line).

(4) Calculation of View Factor from Heater to Surrounding Wall Surface SFHW (JHEAT) = 1.0−SFHH (JHEAT) where SFHW (JHEAT) is the view factor from JHEAT to the surrounding wall surface.

(5) Calculation of view factor from surrounding wall surface to surrounding wall surface SFWW = 1.0-4.0 * AHEAT * (SFHW (1) + SFHW (2)) / A
WALL where SFWW is the view factor from the surrounding wall to the surrounding wall.

Next, the calculation of the radiant energy of each heater shown in FIG. 4 is performed in the following manner. Here, wavelength RAM = 2 to 27
μm and calculate every 1 μm. QH (IHEAT, RAM) = (EPUH (IHEAT, RAM) * AHEAT * C1 * RA
M ^-5 ) / (exp (C2 / (RAM * THEAT (IHEAT))) -1) or QH (IHEAT) = EPUH (IHEAT) * AHEAT * SIG * THEAT (IHEA
T) ⁴

Here, IHEAT: upper and lower heaters (1 to 8) RAM: wavelength QH (IHEAT, RAM): energy of wavelength RAM radiated by IHEAT EPUH (IHEAT, RAM): emissivity of wavelength RAM of IHEAT C1: Constant (3.743 * 10 ⁸ ) C2: Constant (1.4387 * 10 ⁴ ) THEAT (IHEAT): Temperature of IHEAT QH (IHEAT): Energy radiated by IHEAT EPUH (IHEAT): Average emissivity of IHEAT SIG: Constant (5.669 * 10 ^-8 ).

Next, the calculation of the radiant energy of the peripheral wall surface shown in FIG. 5 is performed in the following manner. QW (RAM) = (EPUW (RAM) * AWALL * C1 * RAM ^-5 ) / (exp (C
2 / (RAM * TWALL))-1 or QW = EPUW * AWALL * SIG * TWALL ⁴

Here, QW (RAM): energy of the wavelength RAM radiated by the wall EPUW (RAM): emissivity of the wavelength RAM of the wall TWALL: temperature of the wall QW: energy radiated by the wall EPUW: average emissivity of the wall It is.

Next, the calculation relating to the time-series view factors shown in FIG. 6 is performed in the following manner. However, the calculation is performed every x seconds. (1) Calculation about coordinates of center of PCB PCBPOS = NTIME * VELOCI DELTAX (IHEAT) = HPOS (IHEAT)-PCBPOS L1 (IHEAT) = DELTAX (IHEAT)-(LHEAT / 2.0) L2 (IHEAT) = DELTAX ( (IHEAT) + (LHEAT / 2.0)

Here, PCBPOS: X coordinate of the center of the PCB (entrance X = 0) NTIME: Time at the current Time Step VELOCI: Speed of the conveyor DELTAX (IHEAT): Distance between the center of IHEAT and the PCB in the X direction L1 (IHEAT) , L2 (IHEAT): The distance between the PCB and the front and rear ends of IHEAT.

(2) Calculation of view factor from PCB to heater SFPH (IHEAT) = 2.0 * (SFBASE (DISTZ, L2 (IHEAT), WHEAT /
2.0) -SFBASE (DISTZ, L1 (IHEAT), WHEAT / 2.0)) where SFPH (IHEAT) is a view factor from PCB to IHEAT.

(3) Calculation of view factor from heater to PCB SFHP (IHEAT) = (APCB * SFPH (IHEAT)) / AHEAT

(Equation 2)

Here, SFHP (IHEAT): View factor from IHEAT to PCB APCB: Area of PCB TSFHP: View factor from all heaters on the upper surface to PCB.

(4) Calculation of view factor from surrounding wall surface to PCB SFWP = (2.0 * APCB / AWALL)-(AHEAT / AWALL) * 2.
0 * TSFHP where: SFWP: View factor from surrounding wall to PCB.

(5) Calculation of the ratio of energy reflected from the heater to the surrounding wall and reaching the PCB RHWP (IHEAT, RAM) = (ROHW (RAM) * SFWP * SFHW (IHEAT))
/ (1.0-ROHW (RAM) * SFWW)

(Equation 3)

Here, RHWP (IHEAT, RAM) is the ratio of the energy of the wavelength RAM of the IHEAT reflected on the surrounding wall surface and reaches the PCB. ROHW (RAM) is the reflectance of the surrounding wall surface of the wavelength RAM. RHWP (IHEAT): Energy is reflected on the surrounding wall and PC
This is the percentage that reaches B.

Next, calculation of the energy received by the calculation element is executed. [1] Calculation for each material of the object to be heated (calculated by the number of materials) The calculation element shall be thick enough not to transmit infrared rays.
Only the elements at the boundary with the air are handled. The element is parallel to the heater: X = 1, vertical: X = 0 The view factor at an arbitrary position perpendicular to the heater is 2 at the parallel position.
5%.

First, the energy directly received from the heater by the calculation elements shown in FIG. 7 is calculated in the following manner. SQHP (IHEAT, RAM) = (X- (X-1) * 0.25) * SFHP (IHEAT) *
EPUP (RAM) * QH (IHEAT, RAM) / APCB

(Equation 4) Or SQHP (IHEAT) = (X- (X-1) * 0.25) * SFHP (IHEAT) * EPUP
* QH (IHEAT) / APCB

When the calculation element is above the reference plane of the printed board (Z> 0)

(Equation 5)

When the calculation element is below the reference plane of the printed board (Z ≦ 0)

(Equation 6)

Here, SQHP (IHEAT, RAM): wavelength directly received by the calculation element from IHEAT
Energy of RAM EPUP (RAM): Wavelength of calculation element Absorption rate of RAM SQHP (IHEAT): Energy directly received by calculation element from IHEAT EPUP: Average absorption rate of calculation element TSQHP: PCB from all upper (or lower) heaters It is the energy directly received.

Next, the energy which the calculation element shown in FIG. 8 directly receives from the surrounding wall surface is calculated in the following manner. SQWP (RAM) = (X- (X-1) * 0.25) * SFWP * EPUP (RAM) * Q
W (RAM) / (2.0 * APCB)

[0045]

(Equation 7) Or SQWP = (X- (X-1) * 0.25) * SFWP * EPUP * QW / (2.0 *
APCB)

Here, SQWP (RAM) is the wavelength RA directly received by the calculation element from the surrounding wall.
M energy SQWP: Energy directly received by the calculation element from the surrounding wall.

Next, the energy reflected by the peripheral wall surface shown in FIG. 9 and received by the calculation element is calculated as follows. SQHWP (IHEAT, RAM) = (X- (X-1) * 0.25) * RHWP (IHEAT)
* EPUP (RAM) * QH (IHEAT, RAM) / (2.0 * APCB)

(Equation 8) Or SQHWP (IHEAT) = (X- (X-1) * 0.25) * RHWP (IHEAT) * EPU
P * QH (IHEAT) / (2.0 * APCB)

(Equation 9)

Here, SQHWP (IHEAT, RAM): IH reflected on the wall surface and received by the calculation element
EAT wavelength RAM energy SQHWP (IHEAT): IHEAT reflected by the wall and received by the calculation element
Energy TSQHWP: Energy of all heaters reflected by the wall and received by the calculation element.

Next, the energy lost by the calculation elements shown in FIG. 10 due to radiation is calculated in the following manner. SQP (RAM) = (EPUP (RAM) * C1 * RAM ^-5 ) / (exp (C2 / / RAM
* TPCB)) -1)

(Equation 10) Or SQP = EPUP * SIG * TPCB ⁴

Here, SQP (RAM): energy of the wavelength RAM radiated by the calculation element TPCB: temperature of the calculation element SQP: energy radiated by the calculation element.

Next, as shown in FIG. 11, the energy balance of the calculation element is calculated. SQ = TSQHP + SQWP + TSQHWP-SQP where SQ is the net energy received by the computational element.

The heat quantity obtained by the above radiation calculation is given to the target calculation element as a boundary condition, and the heat conduction of the object to be heated is analyzed. In the heating furnace, the transfer of heat due to convective heat transfer is often not negligible, and it is needless to say that this should be taken into account.

In the present invention, since the radiation heat transfer is calculated in consideration of the wavelength distribution of the emissivity, absorptance and radiation energy intensity specific to the material of the infrared heater and the object to be heated, the infrared heater and the object to be heated have Divide the wavelength distribution of radiation energy intensity and the wavelength distribution of emissivity and absorptance into a plurality of parts in the infrared wavelength range, calculate the balance of the amount of radiation heat to the object to be heated in each divided wavelength range, and finally calculate these The balance in the divided wavelength range is added.

For this reason, a radiation analysis is performed to determine whether the object to be heated is easily heated with respect to the radiation characteristics of the infrared heater, and whether the radiation characteristics of the infrared heater and the object to be heated are matched, and the object to be heated is thermally analyzed. Can be reflected in the results.

Further, in the thermal analysis of the object to be heated for detecting the temperature of the object to be heated in the infrared heating furnace, the amount of radiant heat received by the object to be heated is calculated by using the object to be heated, the infrared heater,
In order to consider the view factor between the surrounding wall and the like, and this time change, calculate each view factor for each analysis time step or for each of a plurality of time steps, and use this to calculate the radiation heat received by the heater from the heater using the heater. After calculating the amount and calculating the balance of the amount of radiation and the amount of radiation heat radiated by the heated object itself, the heat conduction analysis of the heated object is performed using this as a boundary condition to know the temperature distribution and its time change.

For this reason, it is possible to accurately calculate the time change of the radiation energy according to the relative positional relationship between each heater and the object to be heated. In this way, since the amount of radiated heat and its time change, which are set as boundary conditions for the object to be subjected to heat conduction analysis, can be calculated accurately, a quantitatively accurate analysis result can be obtained, and the accurate temperature of the object to be heated can be obtained. The detection can be performed, and by using this, the heating conditions of the infrared reflow furnace can be set efficiently without actually performing the heating experiment of the printed board.

This technique is used not only for detecting the temperature of the printed wiring board in the infrared reflow furnace and setting the heating conditions of the infrared reflow furnace, but also for controlling the temperature of the printed circuit board in a heating device used for processing, for example, a dried food product. The present invention is also applicable to temperature detection of a heating element and setting of heating conditions of a heating device.

Embodiments Embodiments of the present invention will be described below in detail.

Using an infrared reflow furnace shown in FIG.
Unsteady heat conduction analysis of the printed board P when the printed board P shown in FIG. 13 was heated was performed. It should be noted that the substrate P
Capacitor C and QFP (Quad Flat Packag)
e) type integrated device IC1, SOP (Small Outline Package)
It is assumed that the integrated device IC2 and the connector S are mounted. In FIG. 12, the infrared reflow furnace is constituted by a preheating zone 5, a soaking zone 6, a main heating zone 8, a conveyor 7 for transporting the printed board P in the direction of the arrow, and the like. Above and below the conveyer 7 for transporting the printed board P, planar heaters H corresponding to the preheating zone 5, the soaking zone 6 and the main heating zone 8 are provided at predetermined intervals along the transport direction. I have.

Each zone is maintained at a different temperature by a heater, the preheating zone 5 is 340 ° C., and the soaking zone 6 is 1
70 ° C, soaking zone 7 is 170 ° C, main heating zone 8 is 3
Since the temperature is 60 ° C., the printed board P
The radiation energy received by each was calculated.

Further, the radiation energy radiated from the peripheral wall surface, the radiation energy reflected from each infrared heater to the peripheral wall surface and reaching the printed board P, and the radiation energy from the printed board P to the surrounding space are calculated. A balance calculation was performed.

The calculation of the radiation energy balance is 2
The wavelength of ~ 27 μm was divided at 1 μm intervals, and the measurement was performed for each wavelength range. In the calculation of the radiation energy from the infrared heater H to the printed board P, the view factor from the infrared heater H to the printed board P was smaller than that of the heater H analyzed this time. Since the difference in the form factor from the heater H due to the difference is small, it is assumed that the difference is constant at an arbitrary position on the printed board P. Further, the view factor from the infrared heater H to the plane perpendicular to the heater was set to １ ／ of the view factor from the infrared heater H to the horizontal plane without being calculated again.

The calculation of the form factor and the radiation energy is performed at each time step of the heat conduction analysis because the printed board P moves in the reflow furnace by the conveyor 7 and changes with time. Further, regarding heat exchange by convection heat transfer with the atmosphere in the reflow furnace and the printed board P, here, the heat transfer coefficient is simply fixed,
The calculation was performed with the upper surface and the lower surface of the printed board P being 10 W / m ² K and the temperature of the furnace atmosphere being constant at 140 ° C. (measured value).

From the above calculations, the boundary conditions for each boundary element on the printed board P at each time step are determined, and the transient heat conduction analysis of the printed board P moving from the inlet to the outlet of the reflow furnace (180 seconds) for 180 seconds. Was done. A three-dimensional difference method was used as a heat conduction analysis method.

In this example, in order to prove the quantitative accuracy of the analysis result, an experiment was conducted in which the printed board P on which a thermocouple was installed was heated by a reflow furnace and the temperature profile was measured. The measurement points are points a and b shown in FIG.

FIGS. 14 and 15 show a temperature profile (a) of the analysis result and a temperature profile (b) of the experimental result according to this embodiment, respectively. 14 shows the temperature at point a where the electronic component of the printed board P shown in FIG. 13 is not mounted, and FIG. 15 shows the temperature at point b where the electronic component shown in FIG. 13 is mounted. Accordingly, the temperature profile (a) drawn by the analysis result according to this embodiment is such that the temperature of the substrate under a relatively large electronic component such as a QFP type integrated circuit is lower than the temperature of the substrate not mounted on the substrate. It was confirmed qualitatively correct that it had a similar relationship with the temperature profile curve (b) drawn by the experimental results.

Table 1 quantitatively compares the results of the analysis at the point a in FIG. 13 by the method of this embodiment with the results of the temperature measurement by experiment. Table 2 quantitatively compares the results of the analysis at the point b in FIG. 3 by the method of this example with the results of the temperature measurement by experiment. The results obtained by using the analysis method of the present invention are as follows.
→ 212 ° C) within -3 to + 4 ° C, ±
Error within 2.1%, 168 ° C. for point b
The error is within -5 to + 5 ° C and within ± 3% for the temperature rise of (22 → 190 ° C).

From the above results, according to the method of the present invention, the temperature of the printed board can be detected with high accuracy. By using this detection method, it is possible to efficiently set the heating conditions such as the heater temperature of the reflow furnace without actually heating the printed board in a reflow furnace and measuring the temperature using a thermocouple or the like. is there.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

According to the present invention, in the thermal analysis of a printed circuit board in an infrared reflow furnace, the calculation of the amount of radiant heat received by the printed circuit board and the electronic components on the printed circuit board can be performed by using the object to be heated, the infrared heater, and the furnace inner wall surface. In consideration of the view factor during the time, for example, it is possible to obtain a quantitatively accurate analysis result such as the temperature distribution of the object to be heated and its time change as compared with an analysis method using a conventional radiation calculation method.

Further, since the analysis result has high quantitative reliability, the temperature of the infrared heater and the conveyor speed can be set optimally by executing the analysis at most several times. For this reason, it is possible to obtain the optimum temperature profile of the object to be heated without relying on the intuition and experience of the operator as in the past, and to actually measure the temperature distribution through the object through the infrared heating furnace. Since a simple experiment is not required, workability is good and the equipment operation rate of the heating furnace can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration of an infrared heating furnace used in a calculation method according to the present invention.

FIG. 2 is a flowchart showing an outline of a calculation process according to the present invention.

FIG. 3 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 4 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 5 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 6 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 7 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 8 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 9 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 10 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 11 is a flowchart showing a main part of a calculation process according to the present invention.

FIG. 12 is a configuration explanatory view of an infrared reflow furnace used in an embodiment of the present invention.

FIG. 13 is a top view of a printed board used in the embodiment of the present invention.

FIG. 14 is a temperature profile diagram of a calculated value according to the embodiment of the present invention and an actually measured value according to an experiment.

FIG. 15 is a temperature profile diagram of a calculated value according to the embodiment of the present invention and an actually measured value according to an experiment.

Claims (5)

[Claims] When detecting the temperature of an object to be heated in a heating furnace having an infrared heater by numerical analysis, an infrared wavelength range is divided into a plurality of ranges, and each of the divided wavelength ranges is heated. Calculate the balance between the amount of radiant heat received by the body from the heater and the amount of radiant heat radiated to the surroundings, add these together to calculate the net radiant heat received by the heated body in the furnace,
A method for detecting the temperature of a heated object in an infrared heating furnace, wherein the temperature of the heated object is detected by performing a thermal analysis of the heated object using the boundary conditions as a boundary condition. 2. The step of calculating the balance between the amount of radiant heat received by the object to be heated from the heater and the amount of radiant heat radiated to the surroundings includes calculating a view factor between the infrared heater and the object to be heated, and using the same. 2. The method for detecting the temperature of an object to be heated in an infrared heating furnace according to claim 1, wherein the calculation of the amount of radiation heat is performed. 3. When detecting the temperature of a heated object in a heating furnace having an infrared heater by numerical analysis, when the relative position of the heated object in the heating furnace changes over time, Calculate the view factor between the object and the object as a function of time, use this to calculate the net radiant heat received by the object in the furnace, and use this as the boundary condition for thermal analysis of the object. And detecting the temperature of the object to be heated in the infrared heating furnace. 4. The method according to claim 1 and the method according to claim 2 or 3 are used together to calculate a net radiant heat received by the object to be heated in the furnace, and calculate this as a boundary condition. A method for detecting a temperature of a heated object in an infrared heating furnace, wherein a temperature distribution and a temperature rise of the heated object are detected by performing a thermal analysis of the heated object. 5. The calculation of the net radiant heat received by the object in the furnace, in addition to the amount of radiant heat received by the object directly from the infrared heater,
The infrared heating furnace according to any one of claims 1 to 4, wherein the calculation of the amount of radiation heat is performed in consideration of the amount of radiation heat reflected from the infrared heater to the furnace inner wall and reaching the object to be heated. Temperature detection method of the object to be heated.