JP2002050711A - Sealing method of vacuum vessel for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the sealing method of a vacuum vessel for an electronic component which does not need a vacuum tank provided with a large and complicated mechanism and a vacuum pump having high-level capabilities, lessens the generation of gas in the processes of the sealing method, and can execute sealing of the vacuum container for the electronic component, easily and simply and at low cost, using an inexpensive device. SOLUTION: The sealing method of a vacuum container for an electronic component consists of a process for completing a box-shaped container consisting of a metallic base stand with an airlight insulating terminal and a cover, providing the electronic component in its interior, and airtightly bonding (such as a seam welding) its peripheral edges to the cover; a process for evacuating gas in the interior through small holes provided in the container in a vacuum tank; and a process that a sealing material (such as small metal balls) for blocking the small holes is made to abut on the apertures provided in the outer ends of the small holes in the same vacuum tank; and the sealing member is resistance-welded to the apertures provided in the outsides of the small holes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for enclosing an electronic component in a hermetically sealed container and keeping the interior of the container at a vacuum in order to operate the electronic component in a vacuum environment.

[0002]

2. Description of the Related Art There are many types of electronic components to be operated in a vacuum. For example, an element using a semiconductor is operated in a vacuum or an inert gas to avoid deterioration. In addition, a crystal oscillator or a vibrator for a vibrating gyro sensor, which is required to have high accuracy, is excited in an environment having a degree of vacuum of 1 Pa or less, for example, in order to remove gas resistance to vibration. Is desirable. Therefore, in order to place these electronic elements in a vacuum, first assemble them inside an airtight container (package) in the air, make the necessary connections to the hermetic terminals provided on the container, and then release the air inside the container. Sealing is performed after evacuation.

[0003] Containers are often box-shaped. The container usually comprises two members, a base provided with a group of hermetic terminals and a lid. There are the following methods to airtightly construct the assembled container in which electronic components are mounted and assembled. (1) In the soldering method, the peripheral edges of the base and the lid are joined with molten solder.
(2) In the resistance welding method, for example, a frame-shaped projection is provided on the peripheral edge of the lid, and the projection is brought into contact with the peripheral edge of the base by applying pressure, thereby energizing and joining at once. (3) In the cold welding method, the base and the peripheral edge of the lid which are overlapped are strongly pressed with a mold. (4) The seam welding method is a kind of resistance welding method, in which a pulse-like welding current is repeated at short intervals while moving along a peripheral edge of a base and a lid on which roller-shaped electrodes are overlapped. Sink and join.

[0004] The seam welding technique (4) is also used in an embodiment of the present invention and will be described in detail.
FIG. 4 is a partial cross-sectional view showing a main part (electrode and workpiece) of the seam welding apparatus. In FIG. 4, reference numeral 1 denotes a box-shaped container, and a metal base 1a made of Kovar or the like with an airtight terminal 1b through which a lead wire passes through a glass member;
And a metal lid 1c which is a flat plate. Base 1a and lid 1c
Is subjected to electroless Ni plating or Au plating (for example, within a thickness of several μm). An electronic component 2 is housed in a box-shaped space inside the container 1 and connected to and fixed to a lead wire of the hermetic terminal 1b. The electronic component 2 is a component that is preferably operated in a vacuum, for example, a vibrating body that is a main component of a vibration gyro sensor or an acceleration sensor, or an electronic component made of a semiconductor.

The base 1a is a ceramics base 13 which is an insulating material.
Set on top. For example, a base 13 for ceramics or the like is fixed on a jig table 14 that can be moved linearly or rotationally by a guide device (not shown) and moves together. 12
Reference numerals a and 12b denote tapered and rotating roller electrodes which are connected to the two output terminals of the welding power source 11 and which are pressed against the edge of the lid 1b mounted on the base 1a. Roll while rolling. A continuous pulse-like welding current is generated from the welding power source 11 at short intervals. The welding current mainly flows through the path of the roller electrode 12a, the lid 1b, the base 1a, the other side of the base 1a, the other side of the lid 1b, and the roller electrode 12b. (Since the lid 1b is thin, a short-circuit current through the inside of the lid is small.)

[0006] As a result, the lid 1b and the base 1a are continuously welded at a sufficiently close interval along the peripheral edge thereof, and thus are air-tightly welded at multiple points. In some seam welding, the base material of the lid 1b or the base 1a is not melted much, and it is said that the plating is mainly melted and founded, though depending on welding conditions.
When the planar shape of the container 1 is rectangular, the jig table 14 is rotated by 90 ° after welding of the parallel edges facing each other, and the welding of the remaining opposite edges is performed, so that the lid 1b and the base 1a are connected to each other. Complete hermetic bonding is completed. The seam welding method has an advantage that it can easily cope with a change in the size of the container and can efficiently seal a relatively large container (for example, several tens of mm square).

Returning to the general description of the conventional example. Finally, there are two ways to evacuate the interior of the container. The first method is to weld the peripheral portions of the base and the lid in a vacuum, and the vacuum sealing is completed in one step. For example, in the soldering method, a base and a lid are solder-plated, and contact heating and connection are performed in a vacuum. In the cold weld method, the peripheral portion of the lid and the base that are overlapped with each other are strongly cold-pressed with a metal mold in a vacuum. Alternatively, seam welding of a container having no other hole is performed in a vacuum. In the second method, a small hole communicating with the inside of the container is provided in one of the base and the lid, airtight joining is performed in the atmosphere while leaving the small hole, and then the small hole is transferred to a vacuum. It is a method of closing. As a closing method, there is a method of sealing with molten solder, a method of pressing a soft metal such as indium into small holes, and the like. Although not a small hole, there is a method in which a small pipe of copper or the like is penetrated through a container in advance and brazed, and the pipe is crushed in a vacuum.

[0008]

The above prior art has the following problems. First, in the first method (peripheral sealing in a vacuum), in the soldering method, there is a high possibility that a part of the molten solder vaporizes and scatters and remains in the container, thereby contaminating the internal electronic components. In the cold weld method, especially in order to seal many products at the same time, a large, sturdy mold is moved in a vacuum chamber with high precision so that the upper and lower molds of the mold are translated and a large pressing force is generated. Must be moved. Seam welding machines also have many types of movable parts such as pressure welding, rolling, parallel movement, and rotation, and are therefore large in size. In order to accommodate these devices, an extremely large-sized vacuum chamber is required, and the movable mechanism and the pressurizing mechanism have to be extremely complicated in addition to the need for remote control from the outside. In addition, since occluded gas is generated from a large-area and complicated movable portion, a highly efficient exhaust pump having a high ultimate vacuum is required to efficiently exhaust the inside of the tank. That is, the vacuum device is large and expensive.

The second method (sealing of small holes or the like in a vacuum) has the advantage that a large-scale vacuum facility is not required as in the first method, but the gas is still required in the case of using molten solder. There is a risk of occurrence, and when a soft metal is used, handling is somewhat troublesome and reliability cannot be said to be sufficient. The pipe crushing method requires a preliminary process of pipe welding,
It is not preferable because a considerably large protrusion is formed on the container after sealing.

An object of the present invention is to eliminate the need for a large vacuum tank having a complicated operation mechanism or a high-performance vacuum pump,
An object of the present invention is to provide a vacuum sealing method for an electronic component which generates little gas during the process and consequently can be easily and simply carried out at low cost using a simple and inexpensive apparatus.

[0011]

In order to achieve the above object, a method for sealing a vacuum container of an electronic component according to the present invention has the following features. (1) A step of preparing a metal base with a hermetically insulated terminal and a lid, which are parts of a box-shaped container, and providing a small hole penetrating inside and outside of the container on one of them; Attaching an electronic component to be operated in a vacuum to the airtight insulating terminal and connecting the peripheral portion of the base and the peripheral portion of the lid in the air or gas in an airtight manner. A step of completing the box-shaped container in which the components are installed, and a step of exhausting gas from the small hole in a vacuum chamber, and forming the outer end opening of the small hole in the same vacuum chamber. Abutting a sealing member that closes the small hole and resistance welding the outer opening of the small hole.

The method for sealing a vacuum container of an electronic component according to the present invention may further include at least one of the following features. (2) The seam welding technique is used in the step of hermetically joining the peripheral portion of the base and the peripheral portion of the lid in the atmosphere or gas.

(3) In the resistance welding step, the degree of melting and the degree of deformation of at least a part of the sealing member are larger than the degree of melting and the degree of deformation of the base or the lid to be welded. Large welding conditions (material and shape of sealing member, pressing force, current, material of welding electrode,
Shape).

(4) The sealing member is a metal sphere having a diameter larger than the inner diameter of the small hole, and the metal sphere is mainly melted and deformed and is pushed into the base or lid to be welded. The final protruding height from the surface of the base or the lid is not more than about the original radius of the metal sphere.

(5) The diameter of the material of the metal sphere is preferably 1.3 to 2 times the inner diameter of the small hole.

(6) The sealing member is a small plate having a hemispherical or conical projection, and in the welding step,
The protrusion is inserted into the small hole.

(7) The sealing member is a small plate having a ring-shaped projection.
The ring-shaped projection abuts around the small hole.

(8) A dredging portion is provided at the outer end opening of the small hole, and part or all of the sealing member is submerged in the dredging portion.

(9) The material of the sealing member is stainless steel.

(10) The sealing member is held by magnetic force while the container is being evacuated.

(11) The electronic component is a mechanical vibrator.

[0022]

FIG. 1 is a sectional view of a main part of a small-sized sealing device used in an example of an embodiment of the present invention.
Reference numeral 1 denotes a container to be vacuum-sealed, which is basically the same as that described in the prior art of FIG. The container 1 incorporates an electronic component 2 and includes a base 1a and a lid 1c, both of which are seam-welded in air at atmospheric pressure or in an inert gas in a previous step. The container is placed on an insulating stand 7 made of ceramics or the like. The welding electrode 4 is fixed to one side of the base 7 so as to face the small hole 1 d left in the container 1. The welding electrode 4 is made of a material such as chromium copper to avoid welding.
The magnet 6 is buried inside. The metal ball 3 a made of stainless steel as a sealing member is attracted by magnetic force and is held at the outer end of the small hole 5.

On the other side of the table 7, there is a plunger 7a for pushing the side surface of the container 1, which slides in a linear motion bearing 7d provided on the table 7 in the axial direction. The pressing force (pressing force at the time of welding) is a previously compressed coil spring 7b and a spring receiving plate 7c.
And given by A cam plate 7f is fixed to the left end of the plunger 7a.
The cam plate 7f is turned, and the stopper pin 7e is inserted into the slit 7g.
When the plunger 7a falls, the plunger 7a moves in the direction of arrow 9 by the spring force, slides the container 1, brings the opening of the small hole 1d into contact with the metal ball 3a, and presses it.

The above-mentioned device is only required to perform substantially one degree of freedom (one direction) operation of pressing the sealing member against the small hole in the vacuum chamber, and its structure is simple including its remote control means. In addition, since the pressing force is not large, the whole can be accommodated in a relatively small vacuum chamber (not shown). A welding power source 1 that generates a single current pulse outside the vacuum chamber
0, and the current output line is connected to the welding electrode 4 and the plunger 7a also serving as the other welding electrode via the insulating terminal of the vacuum chamber. Since the movable part of the present apparatus has a very simple structure, generation of occluded gas is small, and a vacuum degree of, for example, about 5/100 Pa suitable for sealing the vibrating body of the electronic component 2 without using a large capacity exhaust pump. Can be easily obtained.

The vacuum sealing step is as follows. Pull the plunger 7a to the left to charge the coil spring 7b,
The cam plate 7f is kept in contact with the stopper pin 7e. The metal ball 3 a is suction-held by the welding electrode 4, and the container 1, whose peripheral edge has been sealed, is placed on a table 7 at a correct position. Small hole 1
d and the metal sphere 3a are slightly separated from each other to facilitate exhaustion of the container 1. In this state, the vacuum chamber is closed and the air is exhausted. When the predetermined degree of vacuum is reached, the operating member 8 having a rotating shaft penetrating the vacuum chamber is rotated by an external handle, the cam plate 7f is hooked and turned, the stopper pin 7e is dropped into the slit 7g, and the plunger 7a is used. Press container 1,
The small hole 1d is brought into contact with the metal ball 3a. Next, the welding power source 10
Switch (not shown) is turned on, and the plunger 7a-
The metal ball 3a is resistance-welded to the container 1 by a current flowing through the path of the container 1, the outer end of the small hole 1d, the metal ball 3a, and the welding electrode 4, thereby completing the vacuum sealing.

The welding conditions were, for example, as follows. The material of the container 1 is Kovar (Fe-Ni-Co alloy), the diameter of the small hole 1d is 1 mm (with a chamfer of 0.3C), the material of the metal ball 3a is SUS304 or SUS440C, the diameter is 1.5 mm, the welding electrode 4 The diameter of the small hole 4a is 1 mm
(0.3 C chamfered on the side in contact with the metal ball 3 a), the pressing force is 150 N, the welding current is 1500 A, and the energizing time is 5
0 ms. When I tried changing the diameter of the metal ball 3a,
At 1 mm, no welding was performed. At 1.2 mm, gas leakage was observed, and at 1.5 mm, complete sealing was achieved. The upper limit of the diameter is even larger, and it seems that up to about 2 mm (or about twice the diameter of the small hole 1d) may be acceptable.

Metal balls are easily available and inexpensive because they are used for ball bearings and the like. The reason why the stainless steel material is used as described above is that the stainless steel material has a higher volume specific resistance and a larger amount of heat generated by energization than other materials, and is suitable for resistance welding. It is also excellent in corrosion resistance and is preferable in terms of product reliability. In addition, resistance welding is possible even if the metal ball is larger than the above upper limit, but in the structure of this example, in order to prevent the projection height from the container surface after sealing welding from becoming excessive, a ball diameter within a certain limit is used. Desirably. Another embodiment in which a metal sphere having a still larger diameter can be used will be described later with reference to FIG.

FIGS. 2A and 2B are enlarged sectional views showing states before and after welding. (A) shows the mutual positional relationship between the electrode 4, the metal ball 3a, and the small hole 1d immediately before welding, and (b) shows the situation after welding. The welding current is applied to the metal ball 3 from the small-area ring-shaped contact surface formed by the chamfered portion of the small hole 4a and the chamfered portion of the small hole 1d.
a, the metal sphere in the vicinity melts and spreads in a flange shape by the pressing force and collapses, and at the same time, the small hole 1d of the container.
3 shows a state where the outer end portion of the metal ball and a part of the metal sphere are considered to be welded because the material component (Fe) is common and has affinity. As described above, since the metal sphere is considerably strongly crushed, the amount of protrusion of the container after the sealing is completed can be, for example, about the radius of the original metal sphere or less.

3 (a), 3 (b) and 3 (c) are partial cross-sectional views showing the arrangement of related parts showing the main parts of another embodiment of the present invention. In each of the embodiments, the shape of the sealing member 3 used is not spherical but different. Each sealing member 3 is stamped from a plastically deformed plate material, and has a convex surface facing the small hole 1d side of the container 1, and the other surfaces are substantially flat. Therefore, the surface of the welding electrode 4 which is in contact with the other surface does not need to be provided with a small hole, so that the surface is flat.
The sealing member 3 of (a) has a hemispherical projection (projection) on a plate material, (b) has a conical projection, and (c) has a small hole 1.
It has a ring-shaped projection that abuts around d.

(A) and (b) show that the welding current concentrates on the contact portion between the edge of the outer end of the small hole 1d and the projection of the sealing member 3 so that the two materials fuse with each other. A ring-shaped contact portion between the apex of the protrusion and the surface of the container 1 is welded. These sealing members have the advantage that the protrusion height after welding is low. The positioning of each sealing member may be performed by using its outer shape (a disk or a square plate), or may be performed by punching a strip as a base material, returning the base material to the base material, and holding the base material on the strip. As in the case, it may be held by being attracted to the surface of the welding electrode 4 by a magnetic force.

FIGS. 5 (a) and 5 (b) are main portions showing a state immediately before welding of a sealing portion (a sealing member is pressed into a small hole but not welded) in still another embodiment of the present invention. It is sectional drawing. In the present embodiment, the small hole 1 of the container 1
A dredging portion 1e was provided at the outer end opening of d, and a part or all of the sealing member 3 (including the metal ball 3a) was submerged in the container. As a result, for example, even if a large-sized sealing member is used, the height of protrusion from the container after welding can be reduced or eliminated, and the risk that the completed product hits another object and the sealing member falls off can be reduced.

Although a plurality of embodiments of the present invention have been described above, the technical scope of the present invention is not limited to these embodiments. For example, the preliminary sealing of the container 1 is not limited to seam welding, and other means, for example, solder or other brazing material may be used, or a small hole may be provided on the lid side, or its inner diameter, chamfer, shape, surface finish. Alternatively, the surface treatment or the like may be changed or added, or a different form or material may be given to the structure of the sealing device, the operating means, the shape or the holding method of the sealing portion or the sealing member, or the like. Also, the welding conditions are not limited to the examples. It is also easy to simultaneously or sequentially perform the sealing operation of a plurality of containers set in parallel in the same vacuum chamber.

[0033]

(1) According to the present invention, as set forth in claim 1,
This is a method in which an airtight container with small holes is completed at atmospheric pressure, exhausted in vacuum, and the small holes are sealed by resistance welding by applying a relatively small pressing force with a simple operation using a sealing member. Therefore, there is no need for a large and complicated vacuum chamber with complicated internal / external operation mechanisms or a high-performance vacuum pump, and there is little gas generation during the process.As a result, inexpensive equipment can be used easily, simply and at low cost. There is an effect that can be implemented.

Further, further individual effects obtained by adding the following constitutions will be listed with numbers corresponding to the respective claims. (2) The use of the seam welding technique for hermetically joining the containers has the effect that even large containers can be easily and reliably sealed.

(3) By providing welding conditions such that the method of the sealing member undergoes greater deformation than that of the container, welding at the sealing portion can be ensured, and the reliability of maintaining the vacuum inside the container can be improved. Was. (4) A metal sphere having a diameter larger than the inner diameter of the small hole of the container is used as the sealing member. The metal sphere is largely deformed and pushed into the container, and the final projection height from the container surface is equal to or less than the original radius of the metal sphere. Therefore, the effect of ensuring the welding of the sealing portion and improving the reliability of maintaining the vacuum was obtained. (5) The diameter of the material of the metal sphere is defined as 1 of the inner diameter of the small hole on the container side.
By setting it to 3 times or 2 times, there is an effect that reliable sealing can be performed.

(6) By using a small plate having a hemispherical or conical projection as a sealing member, a reliable vacuum can be maintained even if the sealing member is not a spherical sealing member, and the height of the projection from the container surface can be reduced. A small sealed shape was obtained. (7) By using a small plate having a ring-shaped projection as the sealing member, it is possible to achieve a reliable vacuum maintenance even if the sealing member is not a spherical sealing member and to obtain a sealing shape with a small projection height from the container surface. Was. (8) Since the sealing member is submerged in the dredging portion provided in the sealing portion, the number of protrusions after sealing can be reduced or eliminated.

(9) By using stainless steel as the material of the sealing member, a sealing method which is excellent in welding property to the material on the container side and has a possibility of being held by magnetic force is obtained. (10) Since the sealing member before welding is held by magnetic force, setting of the sealing device before exhaustion is facilitated, and an efficient vacuum sealing method can be provided.

(11) The method of the present invention has a very comprehensive effect when applied to a case where the electronic component is a mechanical vibrator, mainly because of the degree of the ultimate vacuum and the smoothness of the entire manufacturing process. high.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an apparatus used in an example of an embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views of a main part showing a sealing step using a metal ball as a sealing member in the embodiment of the present invention, wherein FIG. 2A shows a state before sealing and FIG.

FIGS. 3 (a), (b), and (c) are cross-sectional views of essential parts showing the relationship between a sealing member having a different shape, a container, and a welding electrode in another embodiment of the present invention.

FIG. 4 is a sectional view of a main part of an apparatus used for seam welding, which is a conventional technique applicable to the present invention.

FIGS. 5 (a) and 5 (b) are cross-sectional views of essential parts showing a state immediately before welding of a sealing portion in still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 1a Base 1b Airtight terminal 1c Lid 1d Small hole 1e Dredging part 2 Electronic component 3 Sealing member 3a Metal ball 4 Welding electrode 4a Small hole 6 Magnet 7 7a Plunger 7b Coil spring 7c Spring receiving plate 7d Linear motion bearing 7e Stopper Pin 7f Cam plate 7g Slit 8 Operating member 9 Pressure contact direction 10 Welding power supply 11 Welding power supply 12a Roller electrode A 12b Roller electrode B 13 Ceramic table 14 Jig table

Claims (11)

[Claims] 1. A step of preparing a metal base with a hermetically insulated terminal and a lid, which are parts of a box-shaped container, and providing a small hole penetrating inside and outside of the container on one of them. Attaching an electronic component to be operated in vacuum on the base and connecting to the hermetic insulated terminal, and hermetically joining the peripheral part of the base and the peripheral part of the lid in air or gas. A step of completing the box-shaped container in which the electronic component is mounted, a step of exhausting gas inside the small hole in a vacuum chamber, and an outer end opening of the small hole in the same vacuum chamber. Contacting a sealing member for closing the small hole and resistance welding the outer opening of the small hole to the small hole. 2. The electronic component according to claim 1, wherein the step of hermetically joining the peripheral portion of the base and the peripheral portion of the lid in the atmosphere or gas is performed using a seam welding technique. How to seal a vacuum container. 3. In the resistance welding step, the degree of melting and the degree of deformation of at least a part of the sealing member are larger than the degree of melting and the degree of deformation of the base or lid to be welded. 3. The method for sealing a vacuum container of an electronic component according to claim 1, wherein welding conditions (material and shape of sealing member, pressing force, current, material and shape of welding electrode) are given. 4. The sealing member is a metal sphere having a diameter larger than the inner diameter of the small hole, and the metal sphere is mainly melted and deformed and pushed into the base or lid to be welded. 4. The method according to claim 1, wherein a final projecting height from a surface of the base or the lid is equal to or less than an original radius of the metal sphere. 5. The method according to claim 4, wherein a diameter of the material of the metal sphere is preferably 1.3 to 2 times an inner diameter of the small hole. 6. The sealing member according to claim 1, wherein the sealing member is a small plate having a hemispherical or conical projection, and the projection is inserted into the small hole in the welding step. The method for sealing a vacuum container of any one of the electronic components. 7. The sealing member according to claim 1, wherein the sealing member is a small plate having a ring-shaped projection, and in the welding step, the ring-shaped projection abuts around the small hole. A method for sealing a vacuum container of any of the electronic components. 8. A dredging portion is provided at an outer end opening of the small hole,
8. The method according to claim 1, wherein a part or all of the sealing member is submerged in the dredging part. 9. The method for sealing a vacuum vessel of an electronic component according to claim 1, wherein the material of the sealing member is stainless steel. 10. The method for sealing a vacuum container of an electronic component according to claim 1, wherein the sealing member is held by a magnetic force while the container is being evacuated. 11. The method according to claim 1, wherein the electronic component is a mechanical vibrator.