JP5480723B2 - Filament support for thermionic emission - Google Patents

Description

  The present invention relates to a support for supporting a filament that generates thermoelectrons, for example, in a heating apparatus that evaporates metal fine particles from an evaporating dish so that accelerated electrons collide with the heating plate to generate heat. More specifically, the present invention relates to a filament support that supports the filament so as to face the back surface of the heating plate.

  As a heating means capable of quickly evaporating the metal fine powder hanging little by little on the evaporating dish by placing the evaporating dish on the heating plate and heating the evaporating dish to about 2000 ° C. A BBP heater (Back Bombardment Pedestal Heater) as described in Japanese Patent Application Publication No. 2007-84849 (Patent Document 7 below) is used. This is a heating device of a type in which accelerated electrons collide with the heating plate from behind to generate heat. In this electron impact heating apparatus, the thermoelectrons emitted from the filament by energization are accelerated at a high voltage and collide with the back of the heating plate to cause the heating plate to generate heat. Then, a plate-like heated object such as an evaporating dish placed on the heating plate is heated to quickly evaporate the metal fine powder hanging little by little on the evaporating dish.

  FIG. 8 is a diagram showing a conventional example of an electron impact heating apparatus. Although not shown in FIG. 8, the upper part of the stage part 36 is in a vacuum vessel, and the part of the heating plate 32 is placed in a vacuum atmosphere. A coolant passage 37 is formed in the wall of the stage portion 36, and the stage portion 36 is cooled by passing a coolant such as water through the coolant passage 37.

  On the stage portion 36, a heat resistant plate having a flat heating plate 32 on which a thin plate-like heated object such as an evaporating dish made of PBN (pyrolytic boron nitride) having excellent corrosion resistance is placed. A heated object support member 31 is formed. The inside of the heated object support member 31 is airtightly partitioned from the outer space. More specifically, the heated object support member 31 has a cylindrical shape in which the upper surface side is closed by the heating plate 32 and the lower surface side is opened. The lower end portion of the heated object support member 31 has a flange shape, and the lower end portion is fixed to the upper surface of the stage portion 36 and is hermetically sealed by a vacuum seal material 38.

An exhaust passage 34 is formed in the stage portion 36, and the space inside the heated object support member 31 is exhausted and evacuated by a vacuum pump 35 connected to the exhaust passage 34.
Further, a filament 39 is installed inside the heated object support member 31. In FIG. 8, the filament 39 is shown as a symbol graphic and does not represent an actual shape. The filament 39 is provided behind the heating plate 32 of the heated object support member 31 and is electrically connected to the filament heating power source 40. Further, an acceleration voltage is applied between the filament 39 and the heating plate 32 by the electron acceleration power source 41 via the heated object support member 31. The heating plate 32 is grounded and is held at a positive potential with respect to the filament 39. Although not shown, the filament 39 and the reflector 46 are negatively charged at the same potential as the filament 39.

  In such an electron impact heating device, a constant high voltage acceleration voltage is applied between the filament 39 and the heating plate 32 by the electron acceleration power source 41, and when the filament 39 is energized by the filament heating power source 40, Thermoelectrons are emitted, and the negative thermoelectrons toward the reflector 46 are also electrically reflected by the negatively charged reflector 46. Therefore, most thermoelectrons are accelerated by the acceleration voltage and collide with the lower surface of the heating plate 32. For this reason, the heating plate 32 is heated by the electron impact. The temperature of the heating plate 32 is measured by a temperature measuring device 44 by a thermocouple 42, and the temperature is controlled by a controller 47 that controls the filament heating power source 40. The heat generated in the heating plate 32 is reflected by the reflectors 33 and 46 so that the heat is not diffused to an unnecessary portion as much as possible.

  Such a filament support is generally formed by bending a refractory metal wire into an annular shape regardless of the presence of a support member to form a guide, and passing the filament wire through the annular guide. The main point of this filament support is that it maintains the required positional relationship as a filament while having a structure that can be freely expanded and contracted so that thermal stress is not generated in the filament due to thermal expansion caused by changes in the temperature of the filament. is there. Secondly, since the filament is heated to a high temperature of about 2000 ° C., the bracket does not have a welded structure in which the strength is likely to be reduced, and the guide is formed only by bending the wire, which should be called wirework.

  Unlike a general electron gun, for example, an electron gun for an electron microscope, a filament for a BBP heater is disposed at a position close to a heating plate heated to a high temperature of about 2000 ° C., so that it is exposed to a high temperature of 2000 ° C. or higher. Is done. Since the filament is thin with a diameter of around φ0.5, its own weight is not so great, but when a load is applied in a high temperature region, a creep phenomenon that gradually extends occurs, gradually bends due to its own weight, vibration, thermal stress, etc. End up.

  A conventional example of filament support in such an electron impact heating apparatus is shown in FIG. For the filament 23, a high melting point metal wire is used, for example, a tungsten filament. In the structure for supporting the filament 23, mounting holes 26, 26 are formed on the upper and lower sides of the support member 21, and the base ends of the arms 25, 25 of the bracket 22 made of a refractory metal wire are formed in the mounting holes 26, 26. An annular guide 24 is formed at the tip of the arms 25 and 25 of the bracket 22 that penetrates and is fixed and extends to the side of the support member 21. The filament wire 23 passes through the guide 24.

  In the conventional support of the filament 23 shown in FIG. 7A, an annular guide 24 is formed by bending an intermediate portion of a wire made of a high melting point material to be the bracket 22 into a coil shape, and the coil forming this guide 24 is formed. Two arms 25, 25 are extended from the guide 24 in a substantially parallel manner to form a bracket 22. Further, both ends of the two arms 25, 25 of the bracket 22 are passed through a plurality of mounting holes 26, 26 provided above and below the support member 21, respectively, and the arms passed through the upper mounting hole 26 behind the support member 21. The distal end portion of the arm 25 that is passed through the lower mounting hole 26 is bent upward, and vertically attached to the back of the support member 21. Further, a belt-like winding member 27 is wound so as to wind the support member 21 including the tip portions of the arms 25 and 25 attached to the back of the support member 21, and this is partially welded 28. The ends of 25 and 25 are fixed to the support member 21.

  Further, the support of the filament 23 shown in FIG. 7B is formed by bending an end portion of a wire made of a high melting point material to be the bracket 22 into a coil shape to form an annular guide 24, and the coil forming this guide 24 A bracket 22 is formed by extending one arm 25 from a guide 24 having a shape. The tip of one arm 25 of the bracket 22 is bent through the upper and lower mounting holes 26, 26 provided in the support member 21 in order, and the tip of the arm 25 pulled out from the lower mounting hole 26 is used as the support member 21. Then, the arm 25 is fixed to the support member 21 by folding upward.

  In any of the examples, the bracket 22 is formed by a single wire, and a part of the wire is a coil-shaped guide 24 of about double winding. Like the filament support shown in FIGS. 7A and 7B, the filament 23 is supported by one or two arms 25, 25 and an annular guide 24 provided at the tip thereof. When the temperature of the heating plate 32 shown in FIG. 8 becomes as high as 2000 ° C., not only the filament 23 but also the bracket 22 thereof becomes a high temperature of 2000 ° C., and the arm 25 of the bracket 22 bends due to the creep phenomenon described above. The guide 24 is gradually lowered.

  Since the positional relationship of the filament 39 of the BBP heater with respect to the heating plate 32 affects the temperature distribution and withstand voltage of the heating plate 32, the guide 24 shown in FIGS. It is desirable to support the filament 23 to some extent by thermal expansion only in the annular guide 24.

JP 2007-207447 A JP 2005-056964 A JP 2000-266900 A JP 2000-133179 A JP 2000-066000 A JP 07-153368 A JP 2007-084849 A

  In the present invention, in view of the problems in the conventional thermoelectron emission filament support for a BBP heater used at a high temperature, the arm of the bracket supporting the filament is bent due to a creep phenomenon at a high temperature, An object of the present invention is to provide a filament support for thermionic emission in which the guide is not lowered.

  In the present invention, in order to achieve the above-described object, a plate-like member made of a refractory metal having heat resistance is used as the bracket 2, the arm 5 extending from the base end thereof is fixed to the support member 1, and the tip thereof The filament 3 was passed through the guide hole 4 provided on the side, thereby enhancing the rigidity of the bracket 2 in the vertical direction.

  That is, the thermoelectron emission filament support according to the present invention is provided with arms 5 and 5 for fixing to the support member 1 on the base end side of a plate-shaped bracket 2 made of a refractory metal having heat resistance. A guide hole 4 through which the filament 3 is passed is provided on the tip side of the bracket 2, and the arm 5 is fixed to the support member 1 so that the width direction of the bracket 2 is vertical, and the filament 3 is passed through the guide hole 4 of the bracket 2. It is a thing.

Specifically, at least two arms 5 and 5 extending from the upper and lower positions of the base end of the bracket 2 are provided, and these arms 5 and 5 are inserted into mounting holes 6 and 6 provided on the upper and lower sides of the support member 1. Fix it. Further, the bracket 2 is provided with an insertion hole 9 at the base of the arms 5 and 5 extending from the base end side of one refractory metal plate, and is fixed by being inserted into the support member 1 and its mounting holes 6 and 6. The arms 5 and 5 of the bracket 2 are held by a winding member 7 wound through the insertion hole 9.
Alternatively, as another form, the base end side of the bracket 2 is an integral arm 5, and this arm 5 is inserted into a slit 14 provided at the upper end of the support member 1 and fixed.

  In such a thermoelectron emission filament support according to the present invention, the bracket 2 is made of a refractory metal plate, the arm 5 extending from the base end thereof is fixed to the support member 1, and the plate-like bracket 2 The support member 1 is attached so that the width direction is vertical. For this reason, the vertical rigidity of the bracket 2 is increased, and the bracket 2 is less likely to bend up and down. Thereby, the bending of the bracket 2 due to the creep phenomenon is eliminated even under high temperature, and the position of the guide 4 at the tip thereof is not lowered. That is, the filament 3 can be supported at a certain height.

  As described above, in the thermoelectron emission filament support according to the present invention, the vertical rigidity of the bracket 2 is increased, so that the bracket 2 is not easily bent due to a creep phenomenon at a high temperature. Thereby, the guide 4 does not fall under high temperature, and the filament 3 passed through it can be supported at a certain height. Therefore, the influence on the temperature distribution and withstand voltage of the heating plate can be minimized.

It is a disassembled perspective view before attaching the bracket which shows one Example of the support of the filament for electron impact heating apparatuses to a support member. It is a perspective view of the state which attached the bracket which shows one Example of the support of the filament for electron impact heating apparatuses to the support member. It is a disassembled perspective view before attaching the bracket which shows the other Example of the support of the filament for electron impact heating apparatuses to a support member. It is a perspective view of the state which attached the bracket which shows the other Example of the support of the filament for electron impact heating apparatuses to the support member. It is a disassembled perspective view before attaching the bracket which shows the other Example of the support of the filament for electron impact heating apparatuses to a support member. It is a perspective view of the state which attached the bracket which shows the other Example of the support of the filament for electron impact heating apparatuses to the support member. 2 shows two conventional examples of filament support for an electron impact heating device, and is a perspective view of a main part of a portion including a single support member and a bracket for supporting the filament. FIG. It is a schematic longitudinal side view which shows the example of the electron impact heating apparatus to which the support of the said filament is applied.

In the present invention, a plate-like bracket 2 made of a refractory metal is used, and an arm 5 extending from the tip of the bracket 2 is fixed to the support member 1 so that the width direction of the bracket 2 is vertical. The direction rigidity was strengthened, so that the bracket 2 through the filament 3 was not bent due to a creep phenomenon even at a high temperature.
Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to examples.

  An example of a filament support for an electron impact heating device is shown in FIGS. FIG. 1 is an exploded perspective view of a principal part before the bracket 2 is attached to the support member 1 that supports the filament 3, and FIG. 2 is a perspective view of the principal part with the bracket 2 attached to the support member 1.

  For the filament 3, a high melting point metal wire is used, for example, a tungsten filament. The support that supports the filament 3 includes a bracket 2 that supports the filament 3 and a columnar support member 1 that supports the bracket 2. Mounting holes 6 and 6 are formed above and below the support member 1, and the two arms 5 and 5 protruding from the base end of the plate-like bracket 2 are inserted into the mounting holes 6 and 6, and further protruding from the mounting holes 6 and 6. The tips of the arms 5 and 5 are bent up and down along the support member 1 and fixed to the support member 1. Thereby, it fixes to the supporting member 1 so that the width direction of the plate-shaped bracket 2 may become vertical. Further, a guide 4 having a circular opening is provided on the distal end side of the bracket 2, and the filament wire 3 is passed through the guide 4. For the support member 1 and the plate-like bracket 2, a refractory metal having better workability and heat resistance than tungsten is used, for example, tantalum or molybdenum.

  In the filament support shown in FIG. 1, a guide 4 is provided by drilling the tip of a plate made of a high melting point material to be the bracket 2 in a circular shape, and two arms 5 from the end opposite to the guide 4. 5 is extended to form the bracket 2. Furthermore, an insertion hole 9 is provided in the attachment base of the arms 5 and 5 of the bracket 2 by drilling into a rectangular window shape.

  As shown in FIG. 2, the ends of the arms 5 and 5 of the bracket 2 are respectively inserted into a plurality of mounting holes 6 and 6 provided on the upper and lower sides of the support member 1, and further protrude from the mounting holes 6 and 6 to the back of the support member 1. The tips of the arms 5 and 5 are bent up and down along the support member 1 so that the tips of the arms 5 and 5 face each other behind the support member 1. That is, the front end portion of the arm 5 protruding from the upper mounting holes 6 of the support member 1 is bent downward, and the front end portion of the arm 5 protruding from the lower mounting hole 6 of the support member 1 is bent upward. The support member 1 is vertically attached behind. Further, the belt-shaped winding member 7 that has passed through the insertion hole 9 of the bracket 2 is wound so as to wind the support member 1 and the distal ends of the arms 5 and 5 attached to the back thereof. Although not shown, a part of the winding member 7 is welded so that the winding member 7 cannot be unwound. The distal end portion of the arm 5 is fixed to the support member 1 by partially welding the winding member 7. Then, the filament 3 is supported by the guide 4 on the distal end side of the bracket 2.

  The band-shaped winding member 7 is an auxiliary member that fixes the tip of the arm 5 to the support member 1, and is not necessarily required and may be omitted. Moreover, even if the winding member 7 as an auxiliary member is provided, it is not limited to the belt shape, but for example, the linear winding member 7 is wound several times to fix the tip of the arm 5 to the support member 1. You can also. For the winding member 7, a refractory metal having heat resistance is used, for example, tantalum or molybdenum.

Next, the embodiment shown in FIGS. 3 and 4 will be described. FIG. 3 is an exploded perspective view of a main part before the bracket 2 is attached to the support member 1 that supports the filament 3, and FIG. 4 is a perspective view of the main part in a state where the bracket 2 is attached to the support member 1.
In the embodiment described above with reference to FIGS. 1 and 2, the support member 1 is a complete columnar member, and has a circular cross-sectional shape. On the other hand, although the support member 1 in the embodiment shown in FIGS. 3 and 4 is a cylindrical member, the portions where the mounting holes 26 and 26 are opened are flattened as planes 8 and 8. It has become. Thus, by providing the flat surfaces 8 and 8 facing the support member 1 and applying the bracket 2 and the tips of the arms 5 and 5 to this portion, the bracket 2 can be stably supported without swinging sideways. .

  In any of the embodiments shown in FIGS. 1 and 2 and FIGS. 3 and 4, the bracket 2 is formed of a plate material, and a guide 4 serving as a hole is provided at the tip of the plate material. Arms 5 and 5 are integrally extended from above and below the end of the bracket 2 opposite to the guide 4, and mounting holes 6 and 6 are provided at the ends of the arms 5 and 5 above and below the support member 1. Is plugged into. Although the illustrated arms 5 and 5 are provided two vertically, three or more arms may be provided.

Next, the embodiment shown in FIGS. 5 and 6 will be described. FIG. 5 is an exploded perspective view of a main part before the bracket 2 is attached to the support member 1 that supports the filament 3, and FIG. 6 is a perspective view of the main part in a state where the bracket 2 is attached to the support member 1.
In the embodiment described above with reference to FIGS. 1 to 4, the arms 5 and 5 of the bracket 2 protrude from the top and bottom of the base end of the plate-like bracket 2, and are shown in FIGS. 5 and 6. In this embodiment, as shown in FIG. 5, the arm 5 of the bracket 2 extends integrally from the base end of the bracket 2 with the same width. A mounting hole 10 is formed in the arm 5 of the bracket 2.

As shown in FIG. 5, a vertical slit 13 for inserting the arm 5 of the bracket 2 is provided at the upper end of the columnar support member 1. A hole 11 is provided. The width of the slit 13 is slightly wider than the thickness of the arm 5 of the bracket 2, and the diameter of the mounting hole 11 is substantially the same as the mounting hole 10 of the arm 5 of the bracket 2.
Separately, a retaining pin 12 having a slightly smaller diameter than the mounting hole 11 of the support member 1 and the mounting hole 10 of the arm 5 of the bracket 2 is prepared.

  As shown in FIG. 6, the arm 5 of the bracket 2 is inserted into the slit 13 at the upper end of the columnar support member 1, the mounting holes 10 and 11 are aligned, and the retaining pin 12 is inserted into the retaining hole 12. Both ends of the pin 12 are pushed and bent to prevent the retaining pin 12 from coming off and to prevent the arm 5 of the bracket 2 from coming off.

  The filament support according to the present invention supports a filament that generates thermoelectrons facing the back surface of the heating plate, accelerates the generated thermoelectrons to collide with the heating plate, and heats the heating plate. It can be applied to a thermionic emission part of a heating device that heats a heated metal evaporation powder supplied to the substrate to a high temperature.

1 Supporting member 2 Bracket 3 Filament 4 Guide 5 Arm 6 Mounting hole 7 Winding member

Claims (4)

An arm for supporting a filament (3) for generating thermoelectrons, which is fixed to the support member (1) on the base end side of a heat-resistant refractory metal plate-like bracket (2). (5), (5) is provided, a guide hole (4) for passing the filament (3) is provided on the tip side of the bracket (2), and the arm (5) is arranged so that the width direction of the bracket (2) is vertical. ), (5) is fixed to the support member (1), and the filament (3) is passed through the guide hole (4) of the bracket (2). At least two arms (5) and (5) extending from positions above and below the base end of the bracket (2) are provided, and these arms (5) and (5) are provided above and below the support member (1). The filament support for thermionic emission according to claim 1, wherein the filament support is fixed by being inserted into the holes (6), (6). The bracket (2) is provided with an insertion hole (9) at the base of the arm (5), (5) extending from the base end side of one refractory metal plate, and the support member (1) The arms (5) and (5) of the bracket (2) inserted and fixed in the mounting holes (6) and (6) are held by the winding member (7) wound through the insertion hole (9). The filament support for thermal electron emission according to claim 2, wherein the filament support is used. The base end side of the bracket (2) is an integral arm (5), and the arm (5) is inserted into and fixed to a slit (14) provided at the upper end of the support member (1). Item 2. The filament support for emitting thermal electrons according to Item 1.

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