JPH09213456A - Infrared radiation heater and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared radiation heater with high infrared radiation efficiency, and easy to manufacture by forming the heater with cement with high heat conductivity to constitute an infrared radiation surface. SOLUTION: A sheath heater 1 is held in a frame body 2, and a net-shaped body 4 almost parallel to the opening surface of the frame body 2 is arranged within the frame body 2. Cement 5 is filled in the frame body 2, the sheath heater 1 and the net-shaped body 4 are buried in the cement 5 in a panel shape, and the cement 5 is solidified to form an infrared radiation heater 8. The cement 5 filled in the frame body 2 is preferable to have a recessed and projecting part 6 on one surface of the frame body 2 because the infrared radiation efficiency is enhanced. As the cement 5, heat conductive cement having a heat conductivity of 7Kcal/mh deg.C or higher is preferably used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared heater having a high infrared radiation efficiency and easy to manufacture, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As an example of a conventional infrared heater, a sheathed heater or a cartridge heater which is an electric heater is coated on its surface with a ceramic member that emits infrared rays when heated, or a plate-shaped heater. The one in which a ceramic layer is provided on the metal plate in the same manner as described above and the metal plate is separately heated by a heater, the one in which the heater is embedded inside the ceramic member and then the ceramic is fired, and the like, Was known.

[0003]

An infrared heater having an infrared radiation ceramic layer formed on the surface of a heater or a metal to be heated has a good followability of the infrared radiation amount with respect to the temperature rise of the heater and the metal plate, but the infrared radiation is good. The amount is relatively small. Further, it is known that the infrared radiation amount at the same temperature can be increased by forming the ceramic layer thick on the heater.

However, in order to form a thick ceramic layer in a sheath heater or an infrared heater provided by coating the surface of a metal plate with an infrared radiation ceramic layer, it is necessary to form the ceramic layer by multi-layer coating. Therefore, there are problems that a large number of manufacturing processes are required, the manufacturing cost is high, and cracks are likely to occur in a heated state.

Further, when heating a plate-shaped object to be heated, it is necessary to arrange a plurality of sheathed heaters side by side, and it is difficult to uniformly heat and heat the plate-shaped object to be heated due to its constitution. There was a problem.

Further, an infrared heater made by firing a ceramic material requires a firing process in manufacturing,
Further, since the ceramics themselves have a high heat resistance temperature but a low thermal conductivity, there is a problem that the ceramics having a large shape have a poor trackability of the temperature of the ceramics themselves with respect to changes in the heater power and hence changes in the heater temperature.

An object of the present invention is that the manufacturing is easy, the amount of infrared radiation is large, it is possible to uniformly heat a plate-shaped member to be heated, and good followability with respect to changes in the heater power and therefore the heater temperature. By realizing an infrared heater having good controllability, the object to be heated can be heated rapidly and uniformly.

[0008]

The infrared heater of the present invention is characterized in that the infrared emitting surface is formed by molding the heater with cement having high thermal conductivity.

[0009]

According to each claim, there are the following actions.

(1) The invention according to claim 1 of the present invention is
A curable inorganic material, namely cement, can be easily filled, molded and solidified. Further, the solidified cement becomes a good quality ceramic member that emits infrared rays. That is, it becomes a high quality infrared heater that is easy to manufacture. In addition, infrared heaters having various shapes can be easily obtained.

(2) According to the second aspect of the present invention, since the panel-shaped cement is held in the frame body through the electric heater and the mesh-like body, a sturdy panel-shaped heater can be easily manufactured and is of good quality. An infrared heater can be obtained.

(3) Further, according to the invention described in claim 3, by forming the uneven surface, the infrared radiation area is increased, and the radiation efficiency can be further enhanced.

(4) The invention according to claim 4 uses a sheathed heater (electric heater). A stainless steel pipe is used for the exterior of this sheathed heater. The thermal conductivity of stainless steel is about 14 kcal / mh ℃, and in order to obtain an infrared heater with a uniform temperature distribution without a local temperature rise, at least 1/2 or more of the thermal conductivity of stainless steel is required. Will be needed. That is, it is desirable to use a heat conductive cement having a temperature of 7 kcal / mh ℃ or more.

That is, with this, a uniform temperature distribution,
The temperature following property of the heat conductive cement with respect to the heater temperature is good, and an infrared heater that radiates infrared rays to the same extent as a ceramics heater can be obtained. By the way, although it depends on the material, the thermal conductivity of ceramics is small at around 1 kcal / mh ℃.

(5) Further, in the invention according to claim 5, when the cement filled in the frame body is in a semi-solidified state, the cement is projected from the mesh body to form the uneven surface.

[0016]

EXAMPLES Next, practical examples of how the infrared heater of the present invention can be embodied will be described.

1 (a) and 1 (b) are views showing a first embodiment of the present invention, FIG. 1 (a) is a perspective view showing the whole infrared heater, and FIG. 1 (b) is FIG. It is sectional drawing by the II line of (a).

That is, the first embodiment shown in FIG. 1 is an infrared heater formed in a panel shape, and a sheath heater (electric heater) 1 made of stainless steel is inserted into a frame body 2 made of stainless steel or iron. A heater insertion hole 3 is formed to insert and fix the sheathed heater 1, and a mesh body 4 made of a metal mesh is provided inside the frame body 2 and fixed to the frame body 2. The heat transfer cement 5 is poured and molded and solidified into a panel shape.

As a result, the solidified heat transfer cement 5 is fixed to the frame body 2 through the mesh body 4, so that the robust infrared heater 8 can be easily manufactured.

2 (a) and 2 (b) are views showing another shape of the infrared heater of FIG. 1. FIG. 2 (a) is a perspective view of the entire infrared heater as seen obliquely from below, and FIG. b) is shown in FIG.
In the sectional view taken along the line II-II of (a), the same reference numerals as those in FIG. 1 denote the same parts.

That is, as shown in FIGS. 2 (a) and 2 (b), when the heat transfer cement 5 is in a semi-solidified state before being completely solidified, one side of the frame body 2 faces upward and Semi-solidification of the inside of the frame 2 from the other surface of the frame 2 by suspending it in the air or pressing one surface of the heat transfer cement 5 in the frame 2 with a spatula or a plate on one surface of the frame 2. The heat transfer cement 5 in the state is exposed to the mesh body 4 and hangs or jumps out by a slight amount to form the uneven surface 6.

Therefore, the uneven surface 6 increases the surface area. Therefore, since the uneven surface 6 serves as an infrared radiation surface, the radiation efficiency can be improved. And
As described above, the uneven surface 6 can be formed extremely easily.

The heat transfer cement 5 is made of an inorganic material having a hardening property, and its component is sodium silicate 3
It is known that it is composed of 2% and graphites 68%, and its thermal conductivity is about 7 to 12 kcal / mh ° C. In this embodiment, such a heat transfer cement 5 is used.

The original purpose of using the heat-transfer cement 5 is to fill the gap between the heated body such as the sheath heater 1 and the body to be heated with the heat-transfer cement 5 to increase the efficiency of heating. Further, the heat transfer cement 5 is filled in the gap between the cooled body such as a heat pipe and the cooled body to increase the efficiency associated with cooling.

For example, when heating a steel pipe, a pipe-shaped heater is wound around or wrapped around. However, in this case, the heater is only in line contact with the steel pipe, so that the heating efficiency is deteriorated. Therefore, by filling the gap between the heater and the steel pipe with the heat transfer cement and applying the heat transfer cement onto the steel pipe with a thickness to fill the heater, the heater is equivalently adhered to the entire surface of the steel pipe. Similarly, it is used so that it can be heated efficiently. Of course, the same applies when cooling is performed using a heat pipe.

Further, in the heat conductive cement composed of such components, the graphite emits infrared rays in a wide wavelength range. Therefore, it is possible to heat the object to be heated uniformly without being affected by the wavelength dependence of the infrared absorption rate of the object to be heated. That is, in an object to be heated (for example, a wiring board on which a large number of electronic components are mounted) assembled from a plurality of components having different wavelength dependences of infrared absorptance, those components can be heated uniformly.

3 (a) and 3 (b) are perspective views showing a second embodiment of the present invention, and FIGS. 3 (a) and 3 (b) are perspective views showing the whole infrared heater. Is.

This infrared heater is formed by molding a heat transfer cement 5 around a sheath heater 1 into a rod shape and solidifying it. As shown in FIG. 1, a holding member such as a frame 2 or a mesh 4 is used. I haven't. 3A shows a linear sheathed heater 1 and FIG. 3B shows a U-shaped sheathed heater 7 in which the heat transfer cement 5 is molded and solidified to form an infrared heater 9.
It is what constituted.

As described above, the heat transfer cement 5 can be easily molded and solidified into a free shape due to its characteristics, and is extremely excellent in manufacturing an infrared heater. The thermal conductivity of stainless steel is 14 kc.
The value is more than 1/2 of al / mh ℃, and when an infrared heater is created using a sheathed heater with stainless steel exterior, the infrared heater rapidly heats up at almost the same rate as the stainless steel exterior and has high thermal conductivity. Therefore, temperature unevenness is unlikely to occur, and a temperature distribution as uniform as when a metal member is used can be obtained.

By the way, when the thermal conductivity is 7 kcal / mh ° C. or less, temperature unevenness and temperature gradient occur on the heater surface, that is, cement, and it becomes difficult to uniformly heat the object to be heated. And this is remarkable in a panel-shaped heater.

Further, the heat transfer cement 5 becomes a high quality material that emits infrared rays when solidified, and it is possible to extremely easily form a thick cement layer without any trouble, so that a large amount of infrared rays are emitted from the thick cement layer. You will be able to.

Further, in this infrared heater, since the cement radiating infrared rays has a thermal conductivity similar to that of metal, temperature control of the infrared heater can be easily performed.

In other words, it is possible to realize an infrared heater having both a heat conduction characteristic similar to that of a metal material and an infrared radiation characteristic similar to that of a ceramic material.

Therefore, in the infrared heater illustrated in the first embodiment of FIGS. 1 and 2, soldering of a plate-shaped workpiece to be soldered, specifically, solder is previously supplied to the portion to be soldered. The electronic components were mounted on the wiring board that was used to heat it,
It is suitable for a reflow soldering apparatus that melts the solder and performs soldering. That is, it becomes possible to uniformly and efficiently heat each part of the wiring board to manufacture a wiring board having uniform soldering quality.

FIGS. 4A to 4D are views showing the heating conditions and heating characteristics of the wiring board by the panel-shaped infrared heater and the sheathed heater. FIG. 4A shows the infrared rays of the first embodiment. FIG. 4 is a diagram showing conditions for heating the wiring board using a heater.
FIG. 4B is a diagram showing a condition for heating a wiring substrate by using a heater having a far-infrared radiation ceramics layer formed on the surface of a sheathed heater, and FIG. 4C is a diagram showing a condition for heating a wiring substrate by using a sheathed heater. , FIG. 4 (d) is shown in FIG.
In the figure showing the heating characteristics under each condition of (c), the horizontal axis represents time and the vertical axis represents the temperature of the wiring board.

That is, the same sheath heater 1 is used in FIGS. 4A to 4C, and the heater applied power is also the same. The distance D from the heater to the wiring board 11 is also the same, and is set to 95 mm. Then, in this state, a thermocouple-type temperature sensor is attached to the surface of the wiring board 11, and the wiring board 1
This is a measurement of the temporal change (temperature rise) of the temperature of 1.

As can be seen from the measurement results, in the case of FIG. 4A, that is, the panel-shaped infrared heater of the first embodiment, even though the same sheath heater 1 and the same applied power were applied. It can be seen that when 8 is used, the temperature rising rate about twice as high as when only the sheath heater 1 is used can be obtained. Further, in this case, the temperature of each part of the wiring board 11 can be made uniform.

FIG. 5 is a view for explaining an example in which the infrared heater of the first embodiment of FIGS. 1 and 2 and the infrared heater of the second embodiment of FIG. 3 are used in a reflow soldering apparatus. It is a sectional side view of a mounting device. In addition, a part of the hot air circulation system of the reflow portion is shown in a symbol diagram.

That is, the preheating part 13 of the furnace body 12 is provided with two preheating chambers 15, and the reflow part 14 is provided with one reflow heating chamber 16. And each heating chamber 15, 16
Through the carrier device 17 for the wiring board 11. In addition, in each of the preheating chambers 15 of the preheating unit 13, two infrared heaters 8 formed in a panel shape as illustrated in the first embodiment of FIG. 1 and FIG. They are arranged one by one.

The reflow heating chamber 16 of the reflow section 14 is
The blower 18 is configured to perform heating using both hot air and infrared rays.
The hot air atmosphere sucked from the suction port 19 by the heating chamber 2
It is a mechanism in which it is reheated by the heater 21 of 0, blows out from the blowout port 22 and is blown to the wiring board 11. At the hot air outlet 22, a plurality of infrared heaters 9 formed in a channel shape in FIG. 3 are arranged side by side so as to intersect the transport direction A of the wiring board 11. Thereby, the reflow unit 1
In 4, heating of the wiring board 11 is performed by using both hot air and infrared rays.

As described above, by using the infrared heaters 8 and 9 of the first embodiment shown in FIGS. 1 and 2 and the second embodiment shown in FIG. 3 in the reflow soldering apparatus, the wiring board 11 is uniformly and quickly moved. It becomes possible to heat and perform uniform soldering. Also, the controllability of the heating profile is improved.
As a result, it is possible to manufacture a high-quality wiring board 11.

[0042]

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

According to the first aspect of the present invention, the infrared heater can be easily manufactured and the infrared radiation amount is large and the infrared heating can be performed efficiently. Since infrared heaters having various shapes can be easily obtained, it is possible to form an infrared heater that matches the shape of the object to be heated.

According to the second aspect of the present invention, it is possible to easily manufacture an infrared heater formed in a sturdy panel shape, and particularly to heat a plate-shaped object to be heated uniformly.

According to the third aspect of the present invention, a large number of projections and depressions are formed on one surface of the frame, so that the infrared radiation surface becomes large and the radiation efficiency can be further improved.

The invention described in claim 4 is the same as claim 1
In addition to the effect of the second aspect, it becomes possible to obtain a uniform temperature distribution in the infrared heater due to the large thermal conductivity, and further the temperature controllability of the infrared heater is significantly improved. Therefore, it becomes possible to uniformly heat the object to be heated to the target temperature.

According to the fifth aspect of the present invention, the uneven surface for increasing the radiation efficiency can be formed on the radiation surface of the panel-shaped infrared heater by a simple process.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing another shape of the infrared heater of FIG.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing heating conditions and heating characteristics of the wiring substrate by the infrared heater and the sheath heater of the first embodiment of FIG.

FIG. 5 is a side sectional view showing an example in which an infrared heater is used in a reflow soldering device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sheath heater 2 frame 3 insertion hole 4 mesh 5 heat transfer cement 6 convex / concave 7 sheath heater 8 infrared heater 9 infrared heater

Claims (5)

[Claims] 1. An infrared heater, characterized in that it is formed by filling cement around an electric heater and solidifying it. 2. A frame body for holding an electric heater,
A net-like body substantially parallel to the opening surface is provided in the frame body, and the frame body is filled with cement, and the electric heater and the net-like body are embedded in the cement and molded into a panel shape and solidified. Infrared heater characterized by 3. The infrared heater according to claim 2, wherein the cement filled in the frame has irregularities formed on one surface of the frame. 4. A cement having a heat conductivity of 7 kcal / mh.degree. C. or more, which is a heat conductive cement.
The infrared heater according to claim 3. 5. An electric heater is held on the frame, and
A net-like body that is substantially parallel to the opening surface is provided in the frame body, and then the frame body is filled with cement. When the filled cement is in a semi-solidified state before completely solidified,
By suspending one side of the frame body in the air, or by pressing the cement from one surface of the frame body, to form an uneven surface by the cement on the other surface of the frame body, Next, a method for manufacturing an infrared heater, characterized in that the cement is completely solidified.