JP4517376B2 - Sealing method of vacuum container for electronic parts - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for enclosing an electronic component in an airtight container and sealing the container while keeping the interior of the container in a vacuum in order to operate the electronic component in a vacuum environment.
[0002]
[Prior art]
There are many types of electronic components that should be operated in a vacuum. For example, an element using a semiconductor is operated in a vacuum or an inert gas in order to avoid deterioration. In addition, quartz crystal vibrators and vibratory gyro sensor vibrators that require high precision are excited in an environment where the degree of vacuum is within 1 Pa, for example, in order to eliminate the resistance of gas to vibration. It is desirable. Therefore, to place these electronic devices in a vacuum, first assemble them inside an airtight container (package) in the atmosphere and make the necessary connections to the hermetic terminals provided on the container, and then remove the air in the container. After exhausting, sealing is performed.
[0003]
Containers are often box-shaped. The container is usually composed of two members, a base having a hermetic terminal group and a lid. There are the following methods for airtightly constructing the container after the electronic components are mounted inside and assembled. (1) The soldering method joins the peripheral part of a base and a lid 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 pressure contact with the peripheral edge of the base to energize and join at once. (3) In the cold weld method, the overlapped base and the peripheral edge of the lid are pressed strongly with a mold. (4) The seam welding method is a kind of resistance welding method, and the pulsed welding current is repeated at a short interval while moving along the base of the electrode in the form of a roller and the peripheral edge of the lid. Sink and join.
[0004]
The seam welding technique (4) is used in an example of the embodiment of the present invention and will be described in detail. FIG. 4 is a partial cross-sectional view showing the main parts (electrodes and workpieces) of the seam welding apparatus. In FIG. 4, reference numeral 1 denotes a box-shaped container comprising a metal base 1a made of Kovar or the like with an airtight terminal 1b through which a lead wire penetrates a glass member, and a metal lid 1c which is a flat plate. . The base 1a and the lid 1c are subjected to electroless Ni plating or Au plating (for example, within a thickness of several μm). An electronic component 2 is accommodated in a box-shaped space inside the container 1, and is connected to and fixed to the lead wire of the hermetic terminal 1b. The electronic component 2 is preferably a component that is operated in a vacuum. For example, the electronic component 2 is a vibration body that is a main component of a vibration gyro sensor or an acceleration sensor, or an electronic component made of a semiconductor.
[0005]
The base 1a is set on a ceramics base 13 which is an insulating material. For example, a table 13 such as ceramics is fixed on a jig table 14 that can be linearly or rotationally moved by a guide device (not shown) and moves together. Reference numerals 12a and 12b denote tapered roller electrodes which are rotated, and are connected to two output terminals of the welding power source 11, and are pressed against the edge of the lid 1b placed on the base 1a. Roll while. The welding power supply 11 generates a continuous pulsed welding current 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, there is little current short-circuited through the inside of the lid.)
[0006]
As a result, the lid 1b and the base 1a are continuously welded at a sufficiently close distance along the peripheral edge thereof, and thus are airtightly multi-point welded. Depending on the seam welding, depending on the welding conditions, the base material of the lid 1b or the base 1a does not melt so much, and it is said that the foundation is mainly formed by melting the plating. When the planar shape of the container 1 is square, after welding the parallel edges facing each other, the jig table 14 is rotated by 90 °, and welding of the remaining facing edges is performed, the lid 1b and the base 1a Complete hermetic joining. 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).
[0007]
Now, let us return to the general description of the conventional example. There are two ways to finally evacuate the interior of the container. The first method is a method of welding 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, the base and the lid are solder-plated, and contacted and heated in a vacuum for connection. In the cold weld method, the overlapped base and the peripheral edge of the lid are strongly cold-welded with a mold in a vacuum. Alternatively, seam welding is performed in a vacuum-free container. In the second method, a small hole communicating with the inside of the container is provided in either the base or the lid, and the small hole is left in the atmosphere to perform airtight joining, and then moved to a vacuum before the small hole is formed. How to close. As a closing method, there are a method of sealing with molten solder, a method of pressing a soft metal such as indium against a small hole, and the like. Although not a small hole, there is also a method in which a small pipe such as copper is passed through a container in advance and brazed, and the pipe is crushed in a vacuum.
[0008]
[Problems to be solved by the invention]
The above prior art has the following problems. First, in the first method (sealing in a vacuum), in the soldering method, a part of the molten solder is vaporized and remains scattered in the container, and there is a high possibility of contaminating the internal electronic components. In the cold weld method, especially in order to seal a large number of products at the same time, a large and sturdy mold is placed in the vacuum chamber with high accuracy so that the upper mold and lower mold of the mold are translated and a large pressure contact force is generated. It must be moved with. Seam welders also have many different types of moving parts such as pressure welding, rolling, parallel movement, and rotation, and are therefore large. In order to accommodate these devices, a vacuum chamber having a very large volume is required, and the movable mechanism and pressurizing mechanism have to be extremely complicated with the need for remote operation from the outside. Further, occluded gas is generated from a complicated movable part with a large area, and thus an exhaust pump with high efficiency and high ultimate vacuum is required to efficiently exhaust the inside of the tank. That is, the vacuum apparatus is large and expensive.
[0009]
In addition, the second method (sealing the remaining small holes in a vacuum) has the advantage of not requiring a large-scale vacuum facility as in the first method, but there is also a risk of gas generation when using molten solder. In the case of using a soft metal, the handling is somewhat troublesome and it cannot be said that the reliability is sufficient. The pipe crushing method is not preferable because it requires a preliminary step of pipe welding and a considerably large protrusion is formed in the sealed container.
[0010]
The object of the present invention is that it does not require a large vacuum tank with a complicated operation mechanism or a high-performance vacuum pump, generates less gas during the process, and as a result easily and easily uses a simple and inexpensive apparatus. It is an object of the present invention to provide a vacuum sealing method for electronic components that can be carried out simply and at low cost.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the method for sealing an electronic component vacuum container of 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 one of them with a circular small hole penetrating into and out of the container; A step of attaching an electronic component to be operated in a vacuum on a table and connecting it to the hermetic insulation terminal, and a hermetic joining of the peripheral edge of the base and the peripheral edge of the lid in the air or in gas A step of completing the box-shaped container in which the electronic component is embedded; a step of exhausting an internal gas from the small hole in the vacuum chamber; and an outer end opening of the small hole in the same vacuum chamber the small holes said to outer opening and resistance welding of the small holes of the metal balls is pressurized abutment with a diameter greater than the inner diameter of the small hole as a sealing member for closing the said metal ball is mainly melted deformed As a result of being pushed into the surface of the base or lid that is the welding partner, The final projected height of the surface of the base or lid, to a step of such a following original radius of the metal sphere.
[0012]
The electronic component vacuum container sealing method of the present invention may further include at least one of the following features.
(2) The diameter of the material of the metal sphere is 1.3 to 2 times the inner diameter of the small hole.
[0013]
(3) Chamfering was performed on the end portion of the small hole in contact with the metal ball provided on the welding electrode and the outer end opening portion of the small hole provided on the container in the resistance welding.
[0014]
(4) A scooping portion is provided in the outer end opening of the small hole, and a part or all of the metal ball is submerged in the scooping portion.
[0015]
(5) The metal ball is made of stainless steel.
[0016]
(6) The metal ball is held at the cylindrical tip of the welding electrode by a magnetic force at a position distant from the small hole on the axis while the container is being evacuated.
[0017]
(7) Seam welding is used to complete the box-shaped container in which the electronic component is housed by airtightly joining the peripheral edge of the base and the peripheral edge of the lid in the atmosphere or gas. Using technology.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view of a main part of a small 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 contains an electronic component 2 and is composed of a base 1a and a lid 1c, both of which are seam welded in air or an inert gas at atmospheric pressure in the previous step. The container is placed on an insulating base 7 such as ceramics. A 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 chrome copper in order to avoid welding, has a small hole 4a, and has a magnet 6 embedded therein. The metal ball 3 a made of stainless steel as a sealing member is attracted by a magnetic force and is held at the outer end of the small hole 5.
[0023]
The other side of the base 7 is a plunger 7a for pushing the side surface of the container 1, and slides in a linear motion bearing 7d provided on the base 7 in the axial direction. The pressing force (pressure applied at the time of welding) is given by a coil spring 7b and a spring receiving plate 7c that are compressed in advance. A cam plate 7f is fixed to the left end of the plunger 7a, and the right surface of the cam plate 7f is in contact with a stopper pin 7e planted on the base 7. The cam plate 7f is turned and the stopper pin 7e is inserted into the slit 7g. When it 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 pressurizes it.
[0024]
The above-mentioned apparatus is only required to be able to perform substantially one degree of freedom (one direction) operation in which the sealing member is pressed against the small hole in the vacuum chamber, and the structure including the remote control means is simple, and the pressure welding is performed. Since the force is not large, the whole can be stored in a relatively small vacuum chamber (not shown). There is a welding power source 10 for generating a single current pulse outside the vacuum chamber, and its current output line is connected to the welding electrode 4 and the plunger 7a which also serves as the other welding electrode via an insulating terminal of the vacuum chamber. Has been. Since the movable part of this device has a very simple structure, the generation of occluded gas is small, and the degree of vacuum is, for example, about 5/100 Pa, which is suitable when the electronic component 2 seals the vibrator without using a large capacity exhaust pump. Is easily obtained.
[0025]
The vacuum sealing process is as follows. The plunger 7a is pulled to the left to charge the coil spring 7b, and the cam plate 7f is brought into contact with the stopper pin 7e. The metal ball 3a is sucked and held by the welding electrode 4, and the container 1 whose peripheral portion has been sealed is placed on the table 7 at the correct position. The small hole 1d and the metal ball 3a are slightly separated from each other in order to facilitate the exhaust in the container 1. In this state, the vacuum chamber is closed and evacuated. When the predetermined degree of vacuum is reached, the operating member 8 having a rotating shaft that penetrates 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. The container 1 is pushed and the small hole 1d is brought into contact with the metal ball 3a. Next, a switch (not shown) of the welding power source 10 is turned on, and the metal ball 3a is put into the container 1 by the current flowing through the path of the plunger 7a-container 1-small hole 1d outer end-metal ball 3a-welding electrode 4. Resistance welding to complete vacuum sealing.
[0026]
The welding conditions were as follows, for example. The material of the container 1 is Kovar (Fe—Ni—Co alloy), the diameter of the small hole 1d is 1 mm (with chamfering 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 3a), the applied pressure is 150 N, the welding current is 1500 A, and the energization time is 50 ms. When the diameter of the metal sphere 3a was changed, it was not welded at 1 mm, a gas leak was observed at 1.2 mm, and a complete sealing was achieved at 1.5 mm. The upper limit of the diameter is even larger, and it seems that it is acceptable up to about 2 mm (or about twice the diameter of the small hole 1d).
[0027]
Since metal balls are used for ball bearings and the like, they are easily available and inexpensive. The reason why the stainless steel is used as described above is that the stainless steel has a higher volume specific resistance and a larger amount of heat generated by energization than other materials, and is suitable for resistance welding. Moreover, it is excellent also in the point of the reliability of a product excellent in corrosion resistance. In addition, although resistance welding is possible even if the metal sphere is larger than the above upper limit, in the structure of this example, in order not to make the protruding height from the container surface after seal welding excessive, the sphere diameter within a certain limit is used. It is desirable to be. Another embodiment in which a metal ball having a larger diameter can be used will be described later with reference to FIG.
[0028]
2A and 2B are enlarged sectional views showing the states before and after welding. (A) is the mutual positional relationship of the electrode 4, the metal ball 3a, and the small hole 1d just before welding, and (b) is the situation after welding. The welding current enters and exits the metal ball 3a from a 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, and the metal ball in the vicinity melts and spreads in a flange shape by the applied pressure. The state is considered that the outer end of the small hole 1d of the container and a part of the metal sphere are considered to be welded due to the common material component (Fe) and affinity. Since the metal sphere is crushed quite strongly in this way, the amount of protrusion to the outside of the container after completion of sealing can be, for example, less than or equal to the radius of the original metal sphere.
[0029]
FIGS. 3A, 3B, and 3C are partial cross-sectional views of the arrangement of related parts, showing the main parts of another embodiment of the present invention. In each embodiment, the shape of the sealing member 3 to be used is not spherical but different. Each sealing member 3 is punched from a plastically deformed plate, and each has a convex surface toward the small hole 1d side of the container 1, and the other surfaces are substantially flat. Therefore, it is not necessary to provide a small hole on the surface of the welding electrode 4 in contact with the other surface, so that the surface is flat. The sealing member 3 in (a) has a hemispherical projection (projection) on the plate material, (b) has a conical projection, and (c) has a ring-shaped projection abutting around the small hole 1d.
[0030]
(A) and (b) are welding currents concentrated 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 melt together. A ring-shaped contact portion between the top of the container and the surface of the container 1 is welded. These sealing members have the advantage that the protruding height after welding is low. The positioning of each sealing member may use its outer shape (a disk or square plate), or may be punched as a base material, returned to the base material, and held on the strip. You may hold | maintain by attracting | sucking to the surface of the welding electrode 4 with magnetic force like a case.
[0031]
FIGS. 5 (a) and 5 (b) are cross-sectional views of relevant parts showing the state immediately before welding of the sealing part (the sealing member is crimped to the small hole but not welded) in still another embodiment of the present invention. is there. In the present embodiment, a scooping portion 1e is provided at the outer end opening of the small hole 1d of the container 1, and a part or all of the sealing member 3 (including the metal ball 3a) is submerged in the container. Thus, for example, even when a large sealing member is used, the protruding height from the container after welding can be reduced or eliminated, and the risk of the sealing member falling off when the finished product hits another object can be reduced.
[0032]
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, but other means such as solder or other brazing material may be used, a small hole is provided on the lid side, its inner diameter, chamfering, shape, surface finishing 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 of the sealing portion or the sealing member, the holding method, or the like. Of course, the welding conditions are not limited to those illustrated. It is also possible to easily carry out the sealing operation of a plurality of containers set in parallel in the same vacuum chamber simultaneously or sequentially.
[0033]
【The invention's effect】
(1) According to the present invention, as shown in claim 1, a hermetic container having a small hole is completed in an atmospheric pressure, evacuated in a vacuum, and a small hole is simply used by using a metal ball larger than its inner diameter. It is a simple operation and is sealed by resistance welding with a relatively small pressure contact force, so there is no need for a vacuum pump with a large and complicated internal / external operation mechanism, and there is little gas generation in the process, resulting in a low price. Ru can be carried out easily and simply at low cost by using a Do unit. In addition, the metal sphere is greatly deformed and pushed into the container side so that the final projecting height from the container surface is less than or equal to the original radius of the metal sphere, thus ensuring the welding of the sealing part and ensuring the reliability of vacuum maintenance. There is an effect to improve .
[0034]
Further, further individual effects obtained when the configuration of claim 2 or less is added are listed with numbers corresponding to the claims.
(2) By making the diameter of the metal sphere 1.3 to 2 times the inner diameter of the small hole on the container side, there is an effect that a reliable sealing can be performed.
[0035]
(3) A good welding result can be obtained by chamfering the small hole of the welding electrode and the small hole on the container side .
(4) Since the metal ball is submerged in the scooping portion provided in the sealing portion, the protruding portion after sealing can be reduced or eliminated.
[0036]
(5) By using stainless steel as the material of the metal sphere, it is excellent in weldability with the container-side material and can be held by magnetic force.
(6) Since the metal sphere before welding is held by magnetic force, the setting of the sealing device before evacuation becomes easy, and an efficient vacuum sealing method can be provided.
[0037]
(7) By using the seam welding technique for hermetic joining of containers, even a large container can be easily and reliably sealed.
[Brief description of the drawings]
FIG. 1 is a cross-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 main part cross-sectional views showing a sealing process using a metal ball as a sealing member in the embodiment of the present invention, where FIG. 2A is a state before sealing, and FIG. 2B is a state after sealing;
FIGS. 3A, 3B, and 3C are cross-sectional views of main parts showing the relationship between sealing members having different shapes, containers, and welding electrodes in other embodiments of the present invention. FIGS.
FIG. 4 is a cross-sectional view of an essential part of an apparatus used for seam welding, which is a conventional technique applicable to the present invention.
FIGS. 5A and 5B are main part cross-sectional views showing a state immediately before welding of a sealing portion in still another embodiment of the present invention, respectively.
[Explanation of symbols]
1 container 1a base 1b airtight terminal 1c lid 1d small hole 1e scooping part 2 electronic component 3 sealing member 3a metal ball 4 welding electrode 4a small hole 6 magnet 7 base 7a plunger 7b coil spring 7c spring receiving plate 7d linear motion bearing 7e stopper Pin 7f Cam plate 7g Slit 8 Operation member 9 Pressure contact direction 10 Welding power source 11 Welding power source 12a Roller electrode A
12b Roller electrode B
13 Ceramic table 14 Jig table

Claims (7)

Preparing a metal base with a hermetically insulated terminal and a lid, which are parts of a box-shaped container, and providing a circular small hole penetrating into and out 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;
Completing the box-shaped container in which the electronic component is housed by airtightly joining the peripheral edge of the base and the peripheral edge of the lid in the atmosphere or in gas;
Exhausting the internal gas from the small hole in a vacuum chamber;
In the same vacuum chamber, a metal ball having a diameter larger than the inner diameter of the small hole is press-contacted as a sealing member for closing the small hole at the outer end opening of the small hole, and the outer opening of the small hole As a result of resistance welding, the metal ball is pushed into the surface of the base or lid that is the welding partner while being mainly melted and deformed, so that the final protruding height from the surface of the base or lid is A method of sealing a vacuum container for an electronic component, comprising: a step of making the radius less than or equal to an original radius.   The method of sealing a vacuum container for an electronic component according to claim 1, wherein the diameter of the metal sphere material is 1.3 to 2 times the inner diameter of the small hole.   2. The chamfering is performed on the end portion of the small hole that contacts the metal ball provided on the welding electrode and the outer end opening of the small hole provided on the container in the resistance welding. Or the sealing method of the vacuum vessel of the electronic component of 2.   The vacuum container for electronic parts according to any one of claims 1 to 3, wherein a scooping portion is provided in an outer end opening of the small hole, and a part or all of the metal ball is submerged in the scooping portion. Sealing method.   The method for sealing a vacuum container for an electronic component according to any one of claims 1 to 4, wherein the metal sphere is made of stainless steel.   6. The metal ball is held at a cylindrical tip of a welding electrode by a magnetic force at a position distant from the small hole axis while the container is being evacuated. The sealing method of the vacuum vessel of the electronic component in any one.   Seam welding technology is used in the step of completing the box-shaped container with the electronic components inside by airtightly joining the peripheral edge of the base and the peripheral edge of the lid in the atmosphere or gas. The method of sealing a vacuum container for an electronic component according to any one of claims 1 to 6, wherein

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