JP2008130483A - Electron beam fusion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron beam fusion device capable of fusion-welding a minute region by locally heating the minute region of 0.1 mm or less. <P>SOLUTION: This is equipped with an electron beam focusing/deflecting part 1 for generating electron beams and scanning them, a movable stage 8 while retaining a workpiece, a machining chamber 2 in which the stage 8 is housed, and a detector 10 in order to detect secondary electrons or reflected electrons generated at an electron beam irradiation point. By the electron beam focusing/deflecting part 1, the electron beams are irradiated to a desired position of the workpiece, and the workpiece is fusion-welded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electron beam melting apparatus, and more particularly to an electron beam melting apparatus that irradiates a workpiece with an electron beam (electron beam) to melt and bond the workpiece.

  In recent years, mechanical parts have become smaller as referred to as microelectromechanical systems (MEMS), and it has become impossible to use conventional techniques as they are in processing methods. In particular, the fusion joining of a plurality of parts is almost impossible when the heat source is large in the atmosphere and the parts are several mm or less in size. Conventionally, there has been an apparatus for performing melt bonding using an electron beam (electron beam), but there has been no apparatus for melting and bonding a structure having a size of 1 mm or less. However, today, there is an urgent need for a technique for melting and joining parts of 1 mm or less.

Further, as the parts become smaller, it is necessary to accurately grasp the joining portion in order to perform the joining correctly without removing the fusion joining portion. There is a method of obtaining an enlarged image with an optical microscope or an optical microscope and a CCD camera, but when the magnification is increased, the distance between the observation target location and the optical lens is reduced, and the lens and mirror of the optical system are contaminated in a short time. Therefore, it was difficult to maintain a stable image for a long time, and there were many problems in practical use.
In addition, a method using secondary electrons or reflected electrons emitted from a sample when irradiated with an electron beam has been proposed. However, this is a method for finding a welding line from a signal change during one-dimensional scanning. The operability is not always satisfactory.

In recent years, as the miniaturization of parts has become more demanding, there has been an increasing demand for melting and joining parts of 1 mm or less.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an electron beam melting apparatus that can locally heat a minute region of 0.1 mm or less and melt and bond the minute region.

  In order to achieve the above-described object, the present invention includes an electron beam focusing deflection unit that generates and scans an electron beam, a stage that can move while holding a workpiece, and a processing chamber that houses the stage. And a detector for detecting secondary electrons or reflected electrons generated at the electron beam irradiation point, and the electron beam focusing and deflecting unit irradiates a desired position of the workpiece with the electron beam. Are melt-bonded.

According to one aspect of the present invention, a workpiece is melt-bonded by injecting a low-power electron beam of 15 W or less into a region having a diameter of 30 μm or less of the workpiece.
According to one aspect of the present invention, the function of scanning the electron beam of the electron beam focusing deflection unit includes an image observation mode that scans a wide area around the fusion joint and generates an image of a wide area, It features two types of scanning modes, a melt-bonding mode that scans and melts joints in a concentrated manner, and performs both image observation and melt-bonding almost simultaneously by switching both scan modes in seconds. To do.

According to one aspect of the present invention, the melting depth can be changed by changing the depth of focus by changing the opening angle of the electron beam.
According to one aspect of the present invention, an auxiliary heating source for auxiliary heating of the melt-bonded portion with heating means such as an infrared source, a high-intensity light source, or a particle beam source is provided.
According to one aspect of the present invention, a heat shielding mechanism or a cooling mechanism is provided below the electron beam focusing deflection unit or above the stage.

According to one aspect of the present invention, the three-dimensional alignment between the focal point of the electron beam and the fusion-bonded portion of the workpiece having a three-dimensional structure is performed by adjusting the scanning position and the focal point of the electron beam. And
According to one aspect of the present invention, the position and height of the stage holding the workpiece are adjusted by three-dimensional alignment between the focal point of the electron beam and the fusion-bonded portion of the workpiece having a three-dimensional structure. It is characterized by being performed.
According to one aspect of the present invention, the three-dimensional alignment between the focus of the electron beam and the fusion-bonded portion of the workpiece having a three-dimensional structure is automatically performed based on the CAD information.
According to one aspect of the present invention, a fine electron beam for main heating and a wide-area electron beam for auxiliary heating are formed simultaneously.

  In order to weld a part, it is required to melt only the welded part and not the other part. However, when the part is 1 mm or less, it is difficult with the current heating source as described above. For local heating, it is most efficient to inject energy in the form of momentum at the place where heating is desired, where it is converted to thermal energy. When an electron beam accelerated to 30 kV to 50 kV is irradiated onto a metal, the electron beam penetrates into the inside of 5 μm to 10 μm from the metal surface and changes into heat inside, so that efficient local heating is possible.

The present invention generates an electron beam having an energy density of 1 million W (watts) / cm ² or more by generating a current of 30 μA to 500 μA and narrowing the beam diameter to 30 μm or less, preferably 5 to 20 μm. An apparatus capable of locally heating and melting the metal contact portion by joining to the surface is provided. An electron gun having a LaB ₆ (lanthanum hexaboride) cathode can realize a high-density electron beam having a current amount of 150 μA, an electron beam diameter of 15 μm, and a current density of 250,000 A / cm ² . By using the electron beam diameter of 0.05 μm to 30 μm, it is possible to observe a secondary electron image or a reflected electron image with a magnification of 10 to 5000 by applying the principle of a scanning electron microscope.

  When switching the amplitude and speed of the signal that scans the electron beam, if the amplitude is large and the speed is high, the input energy per unit time is small, so the surface does not melt and secondary electrons or reflection from the beam irradiation position Image observation is possible by detecting electrons. When the amplitude is small and the speed is low, melting occurs at the irradiated part and the part can be joined. By switching between two types of scanning modes in seconds, an image observation mode that scans a wide area around the fusion bonding area at high speed, and a fusion bonding mode that concentrates and scans only the vicinity of the joint. Melt bonding can be performed almost simultaneously. As a result, it is possible to accurately melt or melt and join a minute region of 100 μm or less of the workpiece.

  The beam opening angle depends on the diameter of the central hole of the objective aperture attached in the vicinity of the pole piece of the objective lens. When the hole diameter is increased, the depth of focus becomes shallower and the heating range becomes shallower. If the hole diameter is made smaller, the depth of focus becomes deeper and the heating range becomes deeper. The melting depth can be optimized by changing the hole diameter of the objective aperture in accordance with the size and shape of the non-machined part.

When it is desired to finely melt a workpiece having a large heat capacity or a workpiece having a high thermal conductivity, the electron beam of about 15 W (watt) may not be heated to the melting point. If the total energy of the electron beam is increased, the heating temperature can be increased, but if the electron beam current is increased, for example to 100 W, the shape of the electron gun becomes completely different, and in that case, the power is reduced. In this case, the electron beam does not become thin, and melting at a desired thickness of 100 μm or less is impossible.
In the present invention, the temperature of the work piece is heated to a temperature several hundred degrees lower than its melting point with an auxiliary heating source, and an electron beam with a small power of 15 W or less, preferably 4 W to 15 W, is irradiated, so that the minute portion has a melting point. It is possible to heat up to a desired minute region of 100 μm or less or to perform melt bonding.

The irradiation position is controlled by changing the focus of the electron beam or adjusting the X, Y, and Z axes of the stage based on the three-dimensional information of the surface of the workpiece stored in advance in the CAD data. The positions can be matched, and the focal point of the electron beam can always be tied to the processing position.
By adjusting the scanning range and scanning speed of the electron beam according to the surface shape and the surface material, the input energy per area can be adjusted, and non-uniformity of melting or fusion bonding can be eliminated.

In order to increase the heating temperature during welding, an electron beam emitted from the periphery of the tip of the electron gun tip, which is not used in a normal electron microscope or electron beam drawing apparatus, is used. By actively utilizing spherical aberration and focusing on the workpiece, a low-density and large-diameter electron beam (wide-area electron beam) is formed. By irradiating the workpiece with a high-density and fine electron beam simultaneously emitted from the tip of the electron gun tip with the wide-area electron beam, welding can be performed in a state where the welding peripheral portion is auxiliary heated.
As a result, the total energy of the electron beam is 1.5 to 2 times that of the case where auxiliary heating is not performed, and a high heating temperature can be obtained, and the temperature gradient of the welded part is moderated, so that local residual stress is alleviated. Can be made.

  According to the present invention, since welding can be performed while observing with an SEM image, it is possible to weld parts having a fine dimension of 0.1 mm or less, which is impossible with the conventional method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an electron beam melting apparatus according to the present invention. As shown in FIG. 1, the electron beam melting apparatus includes an electron beam focusing / deflection unit 1 and a processing chamber 2 disposed below the electron beam focusing / deflection unit 1. The electron beam focusing / deflection unit 1 includes an electron gun 4, a condenser lens 5, an objective lens 6, an electron beam deflector 7 and the like housed in the focusing deflection unit 3. The focusing deflection unit 3 and the processing chamber 2 are evacuated by a vacuum exhaust system (not shown) provided below the processing chamber 2 and provided with a vacuum pump, and are maintained at a predetermined degree of vacuum.

  A stage 8 that holds a workpiece 11 that is a workpiece is installed in the processing chamber 2. The stage 8 is connected to a motor 9, and the stage 8 can move in two orthogonal axes (X and Y axes) and can be positioned at a desired position on the horizontal plane, and the Z-axis direction (height In the vertical direction and can be positioned at a desired position in the vertical direction.

Further, a secondary electron detector 10 is disposed in the processing chamber 2, and secondary electrons emitted from the work 11 when the work 11 is irradiated with an electron beam are detected by the secondary electron detector 10. It is like that.
Instead of the secondary electron detector, a reflected electron detector that detects reflected electrons that are primary electrons emitted from the workpiece may be used.

  The electron gun 4 is connected to an electron gun control unit 12, and the condenser lens 5 and the objective lens 6 are connected to a lens control unit 13. The deflector 7 is connected to the deflector control unit 14. The electron gun control unit 12, the lens control unit 13 and the deflector control unit 14 are connected to a computer 15. The motor 9 is connected to a motor driver 18, and the motor driver 18 is connected to a computer 15. The secondary electron detector 10 is connected to the computer 15 via a signal amplifier 19. CAD data 16 and a display 17 are connected to the computer 15.

  Further, an auxiliary heating source 20 having heating means such as an infrared ray source, a high-intensity light source or a particle beam source is disposed in the processing chamber 2, and the auxiliary heating source 20 heats the fusion bonding portion of the work 11. Be able to. Since radiant heat from the heated workpiece is transmitted to the electron beam focusing / deflection unit 1 and the stability of the electron optical system may be deteriorated, heat shielding is provided below or below the electron beam focusing / deflection unit 1 or above the stage 8. A mechanism 21 is provided. Instead of the heat shielding mechanism 21, a cooling mechanism that cools the lower part or the bottom part of the electron beam focusing deflection unit 1 may be provided.

  In the above-described configuration, the electron beam (electron beam) emitted from the electron gun 4 is narrowed down by the condenser lens 5 and the objective lens 6 and then passed through the deflector 7 on the surface of the work 11 placed on the stage 8. Focus.

  The deflector control unit 14 controls the amplitude of scanning the electron beam, obtains a magnified image of the surrounding by scanning a wide area, stores the image, and displays the magnified image on the display 17 for a while. In units, the desired portion is melted by switching to a narrow-width scan of only the portion to be melted. By displaying the magnified image and repeating the melting, it is possible to realize highly accurate processing without removing the weld line. When the heat capacity of the workpiece 11 is large or the thermal conductivity is large, the auxiliary heating source 20 is operated to perform auxiliary heating as much as necessary, and an electron beam is irradiated to melt a minute portion. The three-dimensional information on the surface of the workpiece 11 is sent from the CAD data 16 to the computer 15, and the computer 15 based on the CAD data 16, the electron gun control unit 12, the lens control unit 13, the deflector control unit 14, and the motor driver 18. The electron beam and the stage 8 are controlled via the head so that the electron beam is always focused on the surface of the work 11. By controlling the total energy of the electron beam that irradiates one point on the surface of the workpiece, the adjacent beam is irradiated with the electron beam one after another. If the surface shape of the workpiece is different, the energy of the irradiated electron beam is changed. It adjusts and it controls based on CAD data 16 so that it may always melt at a constant level. By repeating the above operation, a desired melt-bonded portion is melted and joined.

  FIG. 2 is a conceptual diagram showing an image observation mode and a melt bonding mode. FIG. 2 shows a case where the first workpiece 11-1 and the second workpiece 11-2 are welded, and the first workpiece 11-1 and the second workpiece 11-2 are at a fusion-bonded point (welded point) 101. Welded. The deflector control unit 14 switches the amplitude and speed of the signal for scanning the electron beam and scans a wide area (image observation mode scanning area) including the melt-bonded portion at a high speed by increasing the amplitude and speed. Image observation and melt bonding are switched by switching the image observation mode and the melt bonding mode in which the amplitude is small and the speed is slowed down and the melt bonding region (melt bonding scanning region) is concentrated and scanned in units of seconds. Are performed almost simultaneously. In the image observation mode, a wide area is scanned, secondary electrons or reflected electrons are used as signals, the area is imaged, and the position of the weld line is recognized. In the melt bonding mode, the fine region can be accurately melt-bonded by matching the position of the welding line obtained in the image observation mode with the welding line scanning while recognizing the position of the welding line. In FIG. 2, a rectangular area denoted by reference numeral 201 represents an image observation mode scanning area, and a hatched rectangular area denoted by reference numeral 202 represents a melt bonding mode scanning area. Reference numeral 203 denotes a deflection center in the electron beam deflector 7.

  FIG. 3 is a conceptual diagram showing a screen of the display in the image observation mode when the image observation mode and the melt bonding mode are used in combination. As shown in FIG. 3, in the image observation mode, the screen of the display unit 17 shows the first work 11-1 and the second work 11-2, and further the first work 11-1 and the second work 11-. A melt-bonded portion (welded portion) 101 for joining 2 is shown.

  FIG. 4 is a conceptual diagram showing the depth of focus when the hole diameter of the aperture (objective diaphragm) attached in the vicinity of the pole piece of the objective lens is small. As shown in FIG. 4, when the hole diameter d of the aperture 301 is small, the focal depth fd becomes deep. In FIG. 4, reference numeral 302 indicates a focal position. When the hole diameter d of the aperture 301 is small, the depth of focus fd becomes deep, which is effective for deep welding.

  FIG. 5 is a conceptual diagram showing the depth of focus when the hole diameter of the aperture (objective aperture) is large. As shown in FIG. 5, when the hole diameter d of the aperture 301 is large, the focal depth fd becomes shallow. In FIG. 5, reference numeral 302 indicates a focal position. When the hole diameter d of the aperture 301 is large, the focal depth fd becomes shallow, which is effective when performing shallow welding. This is particularly effective when shallow penetration is required, such as thin plate welding.

A workpiece that is a workpiece has an uneven surface and a three-dimensional structure. For this three-dimensional structure work, three-dimensional alignment of the focal point of the electron beam and the fusion joint is performed by adjusting the scanning position and focal point of the electron beam, or the position and height of the stage 8 holding the work 11. This is done by adjusting the height.
In this case, the three-dimensional structure of the workpiece 11 is stored in advance in CAD data (CAD information) 16, and based on the stored CAD data 16, the focal point of the electron beam and the tertiary of the melt-bonded portion are calculated by the computer 15. The original alignment is controlled.

  FIG. 6 is a diagram showing an example of the screen of the display when welding is performed with a high-density electron beam. The photograph shown in FIG. 6 shows an SEM image in a state in which two stainless plates having a thickness of 30 μm are stacked and the ends thereof are melt-bonded. The upper half is welded over a long distance by moving the workpiece sequentially upward while the two plates are melt bonded and the lower half is not yet bonded.

FIG. 1 is a block diagram showing the overall configuration of an electron beam melting apparatus according to the present invention. FIG. 2 is a conceptual diagram showing an image observation mode and a melt bonding mode. FIG. 3 is a conceptual diagram showing a screen of the display in the image observation mode when the image observation mode and the melt bonding mode are used in combination. FIG. 4 is a conceptual diagram showing the depth of focus when the hole diameter of the aperture (objective diaphragm) attached in the vicinity of the pole piece of the objective lens is small. FIG. 5 is a conceptual diagram showing the depth of focus when the hole diameter of the aperture (objective aperture) is large. FIG. 6 is a diagram showing an example of the screen of the display when welding is performed with a high-density electron beam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electron beam focusing deflection part 2 Processing chamber 3 Focusing deflection part 4 Electron gun 5 Condenser lens 6 Objective lens 7 Deflector 8 Stage 9 Motor 10 Secondary electron detector 11 Work 12 Electron gun control unit 13 Lens control unit 14 Deflector control Unit 15 Computer 16 CAD data 17 Display 18 Motor driver 19 Signal amplifier 20 Auxiliary heating source 21 Heat shield mechanism 101 Melting joint (welding location)
201 Image observation mode scanning region 202 Melt bonding mode scanning region 203 Deflection center 301 Aperture 302 Focus position

Claims (10)

Electron beam converging and deflecting unit that generates and scans an electron beam, a stage that can move while holding a workpiece, a processing chamber that accommodates the stage, and secondary electrons or reflected electrons generated at an electron beam irradiation point And a detector for detecting
An electron beam melting apparatus characterized by irradiating an electron beam to a desired position of a workpiece by the electron beam focusing deflection unit and melt-bonding the workpiece.   2. The electron beam melting apparatus according to claim 1, wherein the workpiece is melt-bonded by injecting a low-power electron beam of 15 W or less into a region having a diameter of 30 μm or less of the workpiece.   The function of scanning the electron beam of the electron beam converging deflector includes an image observation mode for generating a wide area image by scanning a wide area around the fusion bonding area, and concentrating and scanning the fusion bonding area. 3. The method according to claim 1, wherein two types of scanning modes, ie, a melt bonding mode for performing melt bonding, are provided, and image scanning and melt bonding are performed substantially simultaneously by switching both scanning modes in units of seconds. Electron beam melting device.   4. The electron beam melting apparatus according to claim 1, wherein the melting depth can be changed by changing the focal depth by changing the opening angle of the electron beam.   The electron beam melting apparatus according to any one of claims 1 to 4, further comprising an auxiliary heating source that auxiliaryly heats the melt-bonded portion with heating means such as an infrared source, a high-intensity light source, or a particle beam source. .   6. The electron beam melting apparatus according to claim 1, wherein a heat shielding mechanism or a cooling mechanism is provided below the electron beam focusing deflection unit or above the stage.   7. The three-dimensional alignment between the focus of the electron beam and the fusion-bonded portion of the workpiece having a three-dimensional structure is performed by adjusting the scanning position and focus of the electron beam. 2. The electron beam melting apparatus according to claim 1.   The three-dimensional alignment between the focal point of the electron beam and the fusion-bonded portion of the workpiece having a three-dimensional structure is performed by adjusting the position and height of the stage holding the workpiece. Item 8. The electron beam melting apparatus according to any one of Items 1 to 7.   9. The electron beam according to claim 7, wherein the three-dimensional alignment between the focal point of the electron beam and the fusion-bonded portion of the workpiece having a three-dimensional structure is automatically performed based on CAD information. Melting equipment.   10. The electron beam melting apparatus according to claim 1, wherein a fine electron beam for main heating and a wide-area electron beam for auxiliary heating are formed simultaneously.

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