JPH0132762Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an infrared continuous heating furnace suitable for use, for example, in thick film firing.

Thick film IC products have conductors, resistors, and
It is made by printing pastes such as dielectrics, inductors, etc. in the desired circuit pattern, and then heating and baking them at temperatures appropriate for each paste. Conventionally, a conveyor furnace in which a furnace core tube (matsufuru) is inserted into a tunnel furnace body has been used as a means of firing, but since the heating is indirect, the processing takes time, and the power consumption and size of the furnace are high. There was also a disadvantage from this point of view.

In order to improve this, a structure has been proposed in which infrared lamps are placed above and below the belt conveyor without providing a furnace core tube in the furnace, and the infrared lamps directly irradiate infrared rays onto the processed material. There is. According to this method, it is possible to bake in a short time by utilizing the property of infrared rays, which have a high absorption rate into the paste. However, in conventional infrared firing furnaces, the furnace temperature was adjusted by controlling the voltage of the infrared lamps above and below the conveyor belt using signals from thermocouples inserted into the furnace. The infrared wavelength varies, and the thick film is fired as a result.
The problem was that the stability of the electrical characteristics of IC products was affected, and in particular, resistance values were likely to fluctuate frequently.

The present invention eliminates the drawbacks of conventional infrared heating furnaces as described above, maintains the furnace temperature with the necessary high precision, and performs heating at a stable and constant wavelength without fluctuations in the infrared wavelength, resulting in short processing time and high heat treatment. quality thick film
The present invention aims to provide a heating furnace of this type that can produce IC products.

To achieve this objective, the present invention provides a continuous heating furnace in which a conveyor belt is passed through a tunnel-shaped furnace body with a heat-resistant lining on the inner surface to form a cylindrical direct heating chamber. An infrared heater is disposed in the upper area of the belt conveyor, and a constant current or constant power control device is used to control the infrared heater so that it irradiates infrared rays of a constant wavelength depending on the object to be processed, regardless of the furnace temperature. A resistance heating heater is disposed in the lower area of the belt conveyor, and the resistance heating heater is connected to the infrared heater through a detector of the furnace temperature created by the heat generated by the heater and the infrared heater. It is configured to be controlled by a control device for the furnace temperature coating roll that is independent from the control system.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Figures 1 to 3 show an embodiment of an infrared continuous heating furnace according to the present invention. 1 is a tunnel-shaped furnace body, which is made of a heat insulating material such as firebrick or ceramic wool; Furnace inlet 1 on both ends
1 and a furnace outlet 12 are opened, and a mirror-like lining 13 made of ultra-heat-resistant crystallized glass or ceramic is provided on the inner surface of the furnace body including the furnace inlet 11 and furnace outlet 12. A tunnel-shaped direct heating chamber 2 is formed in the chamber. The direct heating chamber 2 has a shield 2 that crosses the room.
It is divided into several chambers in the longitudinal direction by 1 and 21.

Reference numeral 3 denotes an inlet tube communicating with the furnace inlet 11, and 4 a cooling tube communicating with the furnace outlet 12. The outer periphery of the cooling tube 4 is surrounded by a water jacket. An inlet 5 and an outlet 6 for the object to be processed W are opened at each end of the inlet cylinder 3 and the cooling cylinder 4, and the sizes of the openings are adjusted by slide doors 7 and 8. 9
A conveyor belt is passed between the inlet 5 and the outlet 6, and is wound around pulleys 91 and 92, and a drive mechanism moves the workpiece W at a predetermined speed between the inlet cylinder 3 - the direct heating chamber 2 - the cooling section 4 It is now being transferred to

Infrared heaters 10 are arranged in the upper region of the belt conveyor of the direct heating chamber 2, and are arranged in groups for each zone A, B, and C of the direct heating chamber 2.
In the illustrated example, a rod-shaped lamp is used as the infrared heater 10, which is directly inserted and supported in the furnace body 1 across the heating chamber 2. Of course, a plate-shaped or mat-shaped unit may be used instead of this configuration.

Reference numeral 14 denotes heaters disposed in the lower region of the belt conveyor in the direct heating chamber 2, and like the infrared heaters 10, they are arranged in groups for each zone A, B, and C. As the heater 14, an ordinary resistance heating element in the form of a spiral wire, a band, or a rod is sufficient, thereby reducing the cost of the apparatus.

Therefore, the infrared heater 10 in each zone is connected to a power supply circuit (power supply circuit) 15, but the present invention provides a constant current or constant power to the power supply circuit 15 as shown in FIG. A device 16 is interposed, and by this constant current or constant power device 16, infrared radiation is always performed at a wavelength temperature that matches the infrared absorption wavelength characteristics of the object to be treated, regardless of changes in the external power source.

In the illustrated example, a constant power device is used, and this constant power device includes a setting device 18 for setting an arbitrary power corresponding to an infrared wavelength optimal for the object to be processed, a current detection coil 17, and a current detection coil 17. A calculation unit 19 that calculates the current value and the voltage from the voltage detection coil 17, compares it with the power input in advance to the setting device 18, and issues a predetermined signal according to the deviation; The controller 20, such as a thyristor unit, adjusts the power supplied to the infrared heater 10 to match the set power based on a signal from the infrared heater 10.

On the other hand, the heater 14 is connected to a power supply circuit 15' that is the same or different from the infrared heater 10,
Furthermore, a control device 22 for controlling the furnace temperature, which is independent from the control system of the infrared heater 10, is interposed in the power supply circuit 15'. The control device 22
, a temperature setting regulator 23 that arbitrarily sets the power (voltage) corresponding to the optimum temperature for the zone, a detector 24 such as a thermocouple that detects the temperature inside the furnace and inputs it to the temperature setting regulator 23, The controller 25, such as a thyristor unit, compares the set temperature with the set temperature using a temperature setting regulator 23, and adjusts or reduces the power supplied to the heater 14 based on a signal corresponding to the deviation. The detector 24 is a heater 14
The conveyor belt 9 is inserted into the upper region thereof, for example, directly below the center of the conveyor belt 9.

In other drawings, reference numeral 26 denotes a gas introduction section provided in each zone A, B, and C of the direct heating chamber 2, into which an inert gas such as nitrogen gas or air is introduced. The gas introduction part 26 has a large number of nozzle holes, and the first
As shown in the figure, the arrangement is such that the introduced gas flows countercurrently to the direction in which the object to be processed is transported. 27 is an infrared test hole, and 28 is a gas-tight shell wall.

Next, the usage conditions and effects of the present invention will be explained. When firing a workpiece printed with a desired circuit pattern using thick film paste, the characteristics of the workpiece W, such as the type of paste (for resistors, conductors, dielectrics, etc.), components, infrared absorption, etc. The optimum irradiation wavelength and the corresponding power or current value according to parameters such as characteristics are set in the setting device 18 of the constant current or constant voltage device 16 in each zone A, B, and C, and the The furnace temperature corresponding to the firing temperature profile is set in the temperature setting controller 23 of each zone, the required atmosphere is supplied from the gas introduction part 26, and power is supplied to the infrared heater 10 and heating heater 14 respectively to directly heat the heating chamber 2. to the firing temperature. Then, the conveyor belt 9 is driven to move the object W to be processed from the entrance 5 at a constant speed.

In this way, the workpiece W is directly charged into the heating chamber 2 from the inlet cylinder 3, and the entire workpiece is first heated in the zone A by the temperature atmosphere formed by the heat generated by both the infrared heater 10 and the heating heater 14. At the same time, the infrared heater 10 in the upper area of the conveyor directly irradiates the workpiece with infrared rays, and as this infrared energy penetrates, the paste rapidly hardens, and is then directly transferred to zone B and zone C of the heating chamber 2. The above-mentioned heating is performed continuously while heating, and the firing is completed in a short time. The fired product is cooled while passing through the cooling tube 4 and taken out from the outlet 6.

In such a firing process, in conventional infrared continuous furnaces, the furnace temperature is controlled by detecting the furnace temperature with a thermocouple and controlling the power of the infrared heater itself. As a result, the wavelength of infrared irradiation caused so-called fluctuation. However, in this invention,
The furnace temperature and infrared heater are controlled separately,
The infrared irradiation is separated from the furnace temperature so that the infrared irradiation is always performed at a constant wavelength depending on the object to be treated. That is,
A current or power that creates an infrared irradiation wavelength corresponding to the characteristics of the object W to be treated is set in the constant current or constant power device 16, and the current or power flows to the infrared heater 10 in the power supply circuit 1.
When the current or power of 5 fluctuates, the current detection coil 17 detects the fluctuation and corrects it via the arithmetic unit 19 and controller 20, so that irradiation at a constant infrared wavelength is always performed regardless of furnace temperature control. I do. In this state, the amount of heat generated by infrared irradiation and the heater 1 in the lower area of the belt conveyor are heated.
The furnace temperature is formed by the synthesis of the heat amount in step 4, and this furnace temperature is continuously detected by the detector 24 at a position close to the conveyor belt, and when a deviation from the preset firing temperature appears, the temperature setting controller 23 The controller 25 is activated by the signal, and the heater 1
Increase or decrease the amount of heat generated in step 4.

For this reason, in each zone A, B, and C of the direct heating chamber 2, it is possible to control the furnace temperature, which is important in the firing process, with high accuracy within the specified specifications, and it is possible to control the furnace temperature independently of the furnace temperature control. , stable infrared irradiation heating is always performed at a constant wavelength, and therefore, efficiency by utilizing infrared rays and high quality with no variation in electrical properties can be achieved at the same time.

The present invention is suitable for drying and baking thick film IC products, and can of course also be applied to heat treatment of general metals or non-metals.

According to the present invention described above, the conveyor belt is passed through the tunnel-shaped furnace body, and an infrared heater is placed in the upper area of the conveyor belt, and a heating heater is placed in the lower area of the conveyor belt, so that the upper and lower parts are heated by infrared irradiation. The furnace structure can be made cheaper than that of the infrared heater 10.
is connected to a constant current or constant power control device 16 for controlling the irradiation of infrared rays of a constant wavelength depending on the object to be processed regardless of the furnace temperature, and the resistance heating heater 14 is connected to the heater 14 and the infrared heater. Through the detector 24 of the furnace temperature generated by both calorific values,
Since it is configured to be controlled by the furnace temperature coating roll control device 22 that is independent of the control system of the infrared heater 10, the furnace temperature can be controlled with high accuracy within the specified range, and the temperature can always be adjusted according to the characteristics of the workpiece. It is possible to irradiate infrared rays with a certain stable wavelength, which enables rapid heating and prevention of wavelength fluctuations at the same time, and has advantages such as making it possible to efficiently produce high-quality thick-film IC products. You can get the same effect.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view showing an embodiment of the continuous infrared heating furnace according to the present invention, FIG. 2 is a vertical front view thereof, and FIG. 3 is a block diagram illustrating the infrared heater and the control system for the heater according to the present invention. It is a diagram. 1...Tunnel-shaped furnace body, 2...Heating chamber, 9...
Belt conveyor, 10... Infrared heater, 13...
...Heat-resistant lining, 14... Heater, 16... Constant current or constant power device, 22... Control device.

Claims (1)

[Claims for Utility Model Registration] A continuous heating furnace of the type in which a conveyor belt 9 is passed through a tunnel-shaped furnace body 1 having a heat-resistant lining 13 on the inner surface to form a cylindrical direct heating chamber 2, the direct heating An infrared heater 10 is installed in the upper area of the belt conveyor in the chamber 2, and a constant current or a constant current is used to control the infrared heater 10 so that it irradiates infrared rays with a constant wavelength depending on the object to be processed, regardless of the furnace temperature. It is connected to the constant power control device 16, and a resistance heating heater 1 is installed in the lower area of the belt conveyor.
At the same time, the resistance heating heater 14 is connected to a furnace temperature court independent of the control system of the infrared heater 10 via a furnace temperature detector 24 generated by the heat generated by both the resistance heater 14 and the infrared heater. An infrared continuous heating furnace characterized in that it is configured to be controlled by a roll control device 22.