JPH11156536A - Sheet heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet heater suitable for a combined usage of an extreme infrared radiation heating and a hot air heating. SOLUTION: A heat generation unit 12 is arranged in a sheet heater body 11 to heat the heater body 11 by the heat generation unit 12 so that an extreme infrared radiation is radiated from the heated surface. Ventilation holes 13 are pierced across the whole surface of the heater body 11. The ventilation holes 13 are formed inside of a heat insulation material 17 formed in a cylindrical shape. When the extreme infrared radiation heating of the sheet heater 10 and a hot air heating are used combined, a work is uniformly heated by securing a smooth flow of the hot air while penetrating the hot air through the ventilation holes 13. Also, a mutual heat interference of the heat generation unit body 12 and the hot air penetrating through the ventilation holes 13 is prevented by the heat insulation material 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar heater used in, for example, a reflow device.

[0002]

2. Description of the Related Art Conventionally, heating means used in a reflow apparatus or the like includes far-infrared heating by far-infrared rays radiated from the surface of a bar-shaped heater or a planar heater arranged on a workpiece, and hot air passing through the heater. Hot air heating is also used.

[0003] A plurality of bar-shaped heaters are arranged, and hot air that has passed between them is blown to a work.
The work is heated with far-infrared heating by far-infrared rays radiated from the surface of each heater and hot-air heating with hot air, for example, in a reflow device. The solder paste is melted.

[0004]

In these conventional heaters, there is a problem that the heater and the hot air mutually interfere with each other and the hot air lowers the surface temperature of the heater or the heater raises the temperature of the hot air. ing.

[0005] Further, since the conventional planar heater does not have a shape capable of transmitting hot air, it is not easy to uniformly heat the work in combination with the hot air heating.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a planar heater suitable for the combined use of far-infrared heating and hot air heating.

[0007]

According to the first aspect of the present invention, there is provided a flat heater body, a heating element disposed inside the heater body for heating the heater body and emitting far-infrared rays, This is a planar heater having a ventilation hole formed over the entire surface of the heater main body.

When the far-infrared heating by the planar heater and the heating by hot air are used in combination, a smooth flow of hot air is ensured while the hot air is transmitted through the ventilation holes, and the work is uniformly heated.

According to a second aspect of the present invention, in the planar heater according to the first aspect, the ventilation hole is formed inside a cylindrical heat insulating material.

When far-infrared heating by the planar heater and heating by hot air are used together, mutual heat interference between the heating element in the heater body and the hot air passing through the ventilation hole is prevented by the heat insulating material.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 10 denotes a planar heater. The outer shape of the planar heater 10 is formed by a flat heater body 11. A heating element 12 that generates heat when energized by a sheathed heater or the like is provided inside the heater main body 11, and ventilation holes 13 are formed in a uniform distribution at positions without the heating element over the entire surface of the heater main body 11. .

As shown in FIG. 2, the heater main body 11 is
The heating element 12 is formed of a heating face plate 14 such as an iron plate that is heated to a high temperature in contact with the heating element 12 and a holding plate 15 that does not contact the heating element 12. The lower surface of the heat generating surface plate 14 is a heat generating surface 14a that emits far-infrared rays.

The inside of the heater body 11, that is, the heat generating face plate 14
A heat insulating material 16 is filled between the pressure plate 15 and the holding plate 15. The heat insulating material 16 is also interposed between the heating element 12 and the holding plate 15.

A heat insulating material 17 formed in a collar shape is fitted to the heater main body 11. The heat insulating material 17 includes a cylindrical portion 18 having a length equal to the thickness of the heater main body 11, A flange portion 19 is engaged with the upper surface of the plate 15, and a ventilation hole 13 is formed inside the cylindrical portion 18.

That is, the cylindrical portion of the collar-like heat insulating material 17
The heating element 12 and the ventilation hole 13 are thermally isolated by 18. In addition, the hole shape of the ventilation hole 13 is not limited to the illustrated circular cross-section, and any cross-sectional shape can be formed.

Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described.

When the sheet heater 10 is used in a reflow furnace, a hot air generator (not shown) including a blower and a heater is disposed upstream of the sheet heater 10 to generate heat. Heating by the far infrared rays 21 radiated from the heat generating surface 14a of the heat generating surface plate 14 heated by the body 12 and heating by the hot air 22 supplied from the hot air generator are positioned below the planar heater 10. Used together with a work (not shown) such as a component mounting board.

When reflow soldering is performed by such heating, the temperature of the hot air 22 is about 250 to 300 ° C., while the temperature of the far infrared rays 21 is about 500 ° C.

In the case of this combined heating, hot air is transmitted through the ventilation holes 13 to prevent the planar heater 10 from becoming an obstacle to the hot air, to ensure a smooth flow of the hot air, and to uniformly heat the work. .

Further, mutual heat interference between the heating element 12 and the hot air passing through the ventilation holes 13 is prevented by the heat insulating material 16 and the cylindrical heat insulating material 17 in the heater main body 11.

That is, the heat generated from the heating element 12 is transmitted only to the heating face plate 14 in contact with the heating element 12, and is not transmitted to the holding plate 15 against which the hot air collides and the ventilation hole 13 through which the hot air passes. The temperature of the hot air can be prevented from rising due to the heat generated from the heating element 12, and the hot air
14 can prevent the surface temperature from dropping.

Further, the heating by the far infrared rays 21 and the heating by the hot air 22 can be easily adjusted according to the work to be reflowed.

For example, far-infrared radiation may be performed according to the absorptance of far-infrared rays depending on the material or color of a mounted component such as an integrated circuit mounted on a printed wiring board as a work via a solder paste, or the shape receiving hot air. And the balance between heating and hot air heating can be easily adjusted.

The ventilation hole 13 of the planar heater 10 may be formed as a passage for cool air in some cases. For example, this planar heater 10
Are disposed on both the upper and lower sides of the work, the lower planar heater (not shown) that is de-energized while reflow heating the upper surface of the work by passing downward hot air through the upper planar heater 10. However, by cooling the lower surface of the work by passing the cold air upward, it is also possible to prevent the mounting components soldered to the lower surface of the work from falling off due to remelting of the solder.

Next, FIG. 3 shows another embodiment of the present invention. In this embodiment, a plurality of heating elements 12a and 12b, each of which can be independently energized, are incorporated in one heater body 11.

As described above, by dividing the configuration of the internal heating elements 12a and 12b, it becomes possible to locally select the on / off or strong / weak of the far infrared heating by the same planar heater 10. .

For example, when the width of the work is small,
The energization to one side of the heating element 12a or 12b protruding from the work is stopped, and the far-infrared heating of one side is not performed.

Further, when the mounting density and heat capacity of the board-mounted components are different depending on the location of the work, the current value to be supplied to the heating element 12a or 12b is also separately controlled correspondingly, so that far infrared heating at different temperatures is performed. Good to do.

The use of these planar heaters 10 is not limited to a reflow apparatus, but can be used, for example, as a pre-heater of a jet type soldering apparatus.

[0031]

According to the first aspect of the present invention, since the heating element is provided inside the flat heater body, and the ventilation hole is formed throughout the entire surface of the heater body, this is a planar heater. When far-infrared heating by the planar heater and heating by hot air are used together, the hot air is transmitted through the ventilation holes to ensure a smooth flow of the hot air and work more efficiently than when the hot air bypasses the planar heater. Can be heated evenly,
Suitable for use with hot air heating.

According to the second aspect of the present invention, the ventilation hole is
When far-infrared heating by a planar heater and heating by hot air are used in combination, the thermal interference between the heating element and the hot air passing through the ventilation holes is prevented by the heat insulating material formed inside the cylindrical heat insulating material. For example, it is possible to prevent both a decrease in the temperature of the heating element due to the hot air and an increase in the temperature of the hot air due to the heating element.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a planar heater according to the present invention.

FIG. 2 is an enlarged sectional view of the upper heater.

FIG. 3 is a plan view showing another embodiment of the planar heater according to the present invention.

[Explanation of symbols]

 11 Heater body 12 Heating element 13 Ventilation hole 17 Insulation material

Claims (2)

[Claims] 1. A heater body having a flat plate shape, a heating element disposed inside the heater body to heat the heater body and emit far-infrared rays, and a ventilation hole formed through the entire surface of the heater body. A planar heater, characterized in that: 2. The planar heater according to claim 1, wherein the ventilation hole is formed inside a cylindrical heat insulating material.