JP2013222956A - Hermetic container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hermetic container for storing a function device, in which disadvantages of a glass type thereof in mechanical strength and downsizing, and disadvantages of expensiveness, environmental load problems, excessive quality, and the like in a ceramic type thereof, are improved.SOLUTION: A hermetic container includes a melt sealing portion for a thin plate composite material and a metal copper layer. There is formed a melt sealing body (stem) for a thin plate composite material substrate made of glass and ceramic, and a conductor made of metal copper, to solve the problems. Prescribed conductors are formed of metal copper on both sides of the thin plate composite material substrate constituting the melt sealing body (stem). A frame-like thin plate composite material substrate is provided on a surface of the substrate for mounting a function device to secure a space for storing the function device and perform hermetic melt sealing with a thin film metal copper. The function device is fixed to the melt sealing body (stem) and sealed with a lid by using a low melting point glass or the like in a vacuum to make a product.

Description

  In view of the fact that a functional device such as a crystal resonator requires a high degree of vacuum space in order to fully perform its functional purpose, the present invention is based on a substrate (stem) and a lid (lid) that form an airtight space for holding the vise. It is related with the structure of the airtight container which becomes.

  Conventionally, as an airtight container requiring high vacuum airtightness, there are a glass type and a ceramic type shown in FIG. 6 (Patent Document 1).

In the recent manufacture of electronic devices, a method for attaching components to a printed circuit board to be used has been greatly asked. That is, a surface mountable (SMT) shaped component is fixed in advance on a tape, wound on a reel, and automatically mounted on a printed circuit board where solder paste is applied by a printing method via a component mounting robot. The manufacturing method to become common.
Therefore, board design engineers have made efforts to increase the automation rate by selecting parts that can be automatically mounted as much as possible. This is because whether or not the components to be used can be surface mounted affects the manufacturing efficiency of the printed circuit board and is related to the cost.

  Most glass-type airtight containers are limited to vertical mounting (VMT), which cannot be automatically mounted, but because they can be manufactured at low cost, some products have conversion adapters that can process lead wires or be surface-mounted. It has been dealt with by applying additional processing. Some glass-type airtight containers can be automatically mounted, but their structure is extremely complex and difficult to miniaturize.

  The ceramic type shown in FIG. 6 is generally a surface mountable product that can be automatically mounted.

Next, from another point of view, I touched on the technical background of both types of airtight containers.
The history of hermetic sealing that secures the vacuum space began with the manufacture of the bulb invented by Edison, and has since moved along with the development of the key device responsible for the development of electronics.
In other words, for the commercialization of key devices inherited from the light bulb industry to the vacuum tube industry, the hermetic sealing technology between glass and metal can be used only when many of these key devices are kept at a high vacuum. For this reason, it has been inevitably developed as a fundamental element production technology.

  Later, when TV broadcasting became full-scale, a hard-to-view area appeared, and satellite stations moved to eliminate this. If the transmission tube used in this satellite station uses a conventional glass envelope, there is a problem that the glass is melted by heat due to dielectric loss of the glass.

  In order to solve this problem, a transmitter tube with a ceramic envelope was developed in the early 1960s. At this time, as a basic elemental technology, a hermetic sealing technology between a high alumina ceramic having an alumina content of 92 to 95% and a metal has been established for the first time in Japan. This is the origin of ceramics in the electronics industry. From this point on, thermal characteristics (thermal conductivity, thermal expansion, heat shock and conductivity, etc.), electrical characteristics (dielectric loss, dielectric constant, high insulation, conductivity, etc.) and mechanical characteristics (pull, fold, etc.) of alumina As a result of its excellent power, etc., it was possible to reduce the size of various electron tubes and to establish stable production devices with the establishment of production technology supported by high reliability in terms of airtightness.

While key devices have changed greatly from vacuum tubes to semiconductors due to technological innovations, both types of hermetic containers have been used for semiconductor devices, taking advantage of their advantages and disadvantages.
However, today, functional devices that require a high degree of vacuum hermeticity are limited to a small number of devices such as tuning fork crystal units.
However, these products have a wide variety of uses such as wristwatches, mobile phones, PCs, etc., and their usage is enormous.

An outline of the method for manufacturing the stem 22 of the vacuum type hermetic container shown in Patent Document 1 shown in FIG. 6 will be described.
A slurry in which alumina ceramic, a small amount of special glass and a binder composed of an organic substance and an organic solvent are sufficiently stirred and mixed is prepared in advance. The slurry is spread by providing a blade capable of controlling the film thickness to produce a sheet mainly composed of plastic alumina having a predetermined film pressure. (In general, this state is called a green sheet.)
A necessary conductor portion 22a is provided on the green sheet by using an organic solvent ink made of molybdenum fine powder containing, for example, several percent of manganese fine powder as a solvent.
In order to secure the vacuum space, this is controlled by the layer thickness 22-1 of the green sheet.
Further, when the conductor connection or wiring is required between the green sheet layers 22-2 and 22-3, the organic solvent ink containing the fine powder is used through the fine through hole 22c penetrating the green sheet. Do this.
The required hermetic stem 22 is obtained by combining the above green sheets according to design requirements and laminating them on a jig and heating and firing in wet hydrogen at about 2,000 ° C.
The lid 33 can be prepared in exactly the same manner.
A functional device such as a crystal resonator 55 is fixed to a conductor portion 22a provided through the stem in a space portion (cavity) of the stem (other electrode 22b for fixing the crystal resonator is not shown).
This is set in a jig in a high vacuum apparatus, and the lid 33 and the upper surface of the stem 22 are sealed with glass 44 that melts at a low temperature, so that the portion containing the crystal resonator is kept in a high vacuum state for the purpose. A device can be supplied.
In order to distinguish from the ceramic substrate described later, a method of producing a package from these high alumina content green sheets is called HTCC (High Temperature Co-Fired Ceramic).

On the other hand, there is a storage container such as a device using a mixed slurry of low temperature fired alumina and glass using the same manufacturing method. See Non-Patent Documents 1 and 2.
The low temperature fired ceramic is named LTCC (Low Temperature Co-Fired Ceramic) and is distinguished from the above-mentioned high alumina ceramic substrate.

Patent Document 2 discloses a case of LTCC using crystallized glass having a relatively high alumina content and capable of low-temperature firing.
In the history of hermetic sealing technology described above, noble metals that cannot form oxides on the surface of the sealed metal, and metals that can only form unstable oxides on the surface, will be hermetic sealed with glass. It has been proven impossible, and there has been no record of hermetic sealing.
As for the structure of the sealed portion between the LTCC substrate and the metal, the metal portion formed on the LTCC substrate by a printing method is configured using a paste-like noble metal fine powder ink. A special glass fine powder and precious metal fine powder are mixed, and a solution in which an organic solvent is dissolved in an organic solvent is added to this to form a paste-like metal ink as a conductor on the substrate, and these are sealed Therefore, the apparent structure is formed by bonding an inorganic material and a metal. However, hermetic sealing is theoretically impossible and has never been put into practical use.
In addition, this kind of both ceramic type airtight container and storage container can be automatically mounted.
JP 2009-284125 A JP-A-2002-252539 KOA Co., Ltd. LTCC multilayer board LTCC package catalog NEC Vacuum Glass Co., Ltd. LTCC Board and Green Sheet Mini Knowledge

Conventional ceramic type airtight containers have the following disadvantages.
(B) The high alumina ceramic type was expensive because the raw material bauxite ore was expensive, and high temperature firing was required in the production process for obtaining alumina and the production process for the airtight container.
In addition, the environmental pollution load is extremely large from the viewpoint of environmental protection.
(B) Airtight containers using high-alumina ceramics are over-grade for functional devices that require vacuum-tightness in all the thermal, electrical and mechanical properties.
(C) Vacuum tightness is not ensured for low alumina ceramic type or crystallized glass type containers. Therefore, it is not a comparison object of the present invention.
The present invention has been made to eliminate the above drawbacks.

  In general, it is said that a composite material in which two kinds of substances that do not react with each other are mixed has an additivity. The essential point for solving the drawbacks of the conventional hermetic containers is the improvement of mechanical strength among the glass properties. On the other hand, the most important points to be aware of in the hermetic sealing between metal and glass are to adhere to the basic principles of thermal expansion characteristics and manufacturing technology for the hermetic sealing between metal and glass.

In the present invention, a borosilicate glass conventionally used for glass-type airtight containers is used as a base, and alumina ceramic spherical particles or a composite material made of alumina filler glass obtained by mixing and firing alumina ceramic particles is used to solve the problem. It is a thing.
In other words, silica is the main component of the glass raw material, which is a general-purpose substance that occupies about 70% of the earth and is extremely inexpensive. In both its manufacture and the manufacturing process of the airtight container using the composite material according to the present invention, the required firing temperature is less than half that of ceramic.

FIG. 1 is a photomicrograph of a composite material fired product 1 using alumina ceramic spherical particles as a base of the present invention, and an enlarged view is copied.

  That is, an alumina filler glass obtained by adding 5 to 60% by weight of alumina particles Y having a diameter of 5 to 50 microns to a granular borosilicate glass having a diameter of 20 to 100 microns and mixed and stirred was dry-pressed and fired at about 950 degrees.

A sample for microscopic observation is sampled from each fired product, and the observation surface is optically polished.
This photograph was copied after photographing a microscope screen, and Z in the figure represents the glass portion after firing. (1) in FIG. 1 is the content of alumina spherical particles: 5 to 10%, (2) is the same: 10 to 20%, (3) is the same: 30 to 60%. It shows the state of being.

  The straight line A-A 'is drawn at an arbitrary place on these drawings, and the ratio of glass to alumina is roughly estimated at (4) in (1), 2.8: 1 in (2), and (3). 1.7: 1.

  The contact area ratio was calculated from the above approximate ratio in order to estimate the contact area between the composite material constituting the hermetic seal and the sealed metal. It was about 16: 1 in (1), 8: 1 in (2), and 3: 1 in (3).

(1)-(3) Composite material Samples for measuring thermal expansion and folding force were prepared from the fired products of each sample, and the values were measured. % Increase.
The fold folding force was about 1.5 to 3 times (60% by weight composite material), which showed a significant improvement in properties.
The transition transition temperature of glass, which is an important index related to the hermetic sealing between metal and glass, was observed to rise up to about 10 ° C., but is in a range where there is no problem. The softening point of the glass contributing to the practice of the present invention could be increased by about 30 ° C.

  The properties improved by these composite materials do not deviate significantly from the requirements for hermetic sealing of metal and glass. In other words, as far as these characteristics are seen, they are within the basic design standard that has been cultivated in the vacuum tube manufacturing technology. Rather, most characteristics improve the reliability as expected and increase the degree of freedom in design. Therefore, as a result of replacing and improving the mechanical strength of the glass material which is the object of the present invention with a composite material capable of functional design, the conventional glass strength and other characteristics can be greatly improved. Thereby, it became possible to use as an alternative product of the airtight container manufactured with the conventional high alumina ceramic material.

In order to provide an inexpensive airtight container by mass production, a method of manufacturing a substrate (stem) of an airtight container by a conventionally known slurry method was adopted. As a metal material for hermetic sealing of glass and metal, creation of the required wiring pattern using metal ink using copper fine powder that has already been proven stable, and lamination with a composite thin plate substrate as necessary Measured.
As a result, an airtight container capable of maintaining high reliability and high vacuum was obtained.
It is also a useful means to use a copper foil instead of the metallic ink using the copper fine powder.

The present invention is based on borosilicate glass, which has been used for many years in the hermetic sealing of glass and metal, and has been used for light bulbs and vacuum tubes. Focused on what is possible. By using the composite material of the present invention, it was possible not only to improve the defects and the expected characteristics of borosilicate glass, but also to break down all the problems that had previously been a problem for both glass and ceramic airtight containers. Is something.
In addition, it is possible to provide an ultra-small and ultra-thin airtight container substrate (stem) at a low cost by introducing a mass production method for manufacturing a conventionally known thin composite substrate using the composite material. It was.
That is,
(1) It is possible to design an extremely minimum surface-mount type airtight container with a simple structure.
(2) Mass production of products is possible at a very low cost.
(3) It is possible to provide a product that can be optimally designed so as not to be over-quality.
(4) An eco-product that consumes less energy during the manufacturing process and has a very low environmental pollution load.

Expanded view of composite material using alumina ceramic spherical particles (1) Alumina content: 5-10% (2): 10-20% (3): 30-60% Manufacturing Examples of Airtight Container Substrate (Stem) for Mass Production (a) Surface Conductor Illustration of Thin Composite Material Substrate (b) Back Conductor Illustration of Thin Composite Material Substrate Illustration of thin composite substrate for functional device storage space (cavity) Configuration explanatory diagram of unit airtight container substrate (stem) Functional device assembly illustration Explanatory drawing of high alumina surface mount type airtight container

Mode for carrying out the present invention: Example

  2 to 4 are diagrams for explaining in detail an embodiment for manufacturing a substrate (stem) of an airtight container according to the present invention. FIG. 5 is a diagram for explaining the mounting of a functional device using the substrate (stem) and the product.

FIG. 2 shows an example of manufacturing an airtight container substrate (stem) for mass production. 20% by weight of granular alumina having a diameter of 5 to 50 microns is added to a fine powder of borosilicate glass passed through a 400 to 250 mesh sieve, and a few percent of an appropriate organic binder, solvent, plasticizer and dispersant are added to the composite material mixture. To make a mud-like thriller.
A raw sheet (green sheet) 1 of a composite material having a desired thickness is manufactured by a doctor blade method capable of controlling the film thickness of this thriller.
If necessary, through holes 3 are provided in the raw sheet of the composite material with a mold.
An enlarged view of the unit substrate (stem) is shown in FIG. Copper fine powder is formed on the raw sheet (green sheet) 1 of the composite material by the printing pattern 2 designed so that the internal conductor patterns 2a and 2b and the connecting conductor 2c provided in the through hole 3 can be printed simultaneously. Print the used metal ink.
Similarly, the metal using copper fine powder by the printing pattern 4 designed so that the conductor used as the external conductors 4a, 4b, and 2c can be printed simultaneously also on the back surface (b) of the raw sheet (green sheet) 1 of a composite material. Print the ink made.

FIG. 3 shows an atmosphere in which a raw sheet (green sheet) 5 of a composite material for securing a space space (cavity) for storing a functional device and a raw sheet (green sheet) 1 prepared in FIG. It is fired at 950 ° C. for about 30 minutes in a controllable firing furnace.
An opening 4 is provided in the raw sheet (green sheet) 5 of the composite material.
It is possible to apply nickel plating or gold plating or the like to the exposed conductor portion in this state.

FIG. 4 is a perspective view of a substrate (stem) 6 for cutting out a unit substrate (stem) from the fired thin plate composite substrate obtained according to the present invention for detailed explanation.
The same technique was used with reference to the process of manufacturing device chips from silicone wafers in the semiconductor industry.
The internal conductor patterns 2a and 2b that are independent from each other are independently connected to the external conductors 4a and 4b by a connecting conductor 2c.
Actually, the green sheet 5 and the green sheet 1 are stacked and fired so that the glass components are melted and hermetically sealed so that the boundary surface is not shown. Oita.
The mutually independent internal conductor patterns 2a and 2b provided on the thin composite substrate 1 ensure a space (cavity) for storing the functional device in the vicinity of the connection portion with the connection conductor 2c provided in the through hole 3. The composite material substrate 5 is hermetically sealed.
That is, at least 50% or more of the glass portion exists on the surface of the composite material substrate that is in contact with each other, so that a stable hermetic seal portion is formed with the copper metal thick film conductor layer.

FIG. 5 illustrates the assembly process of the functional device.
A functional device 7 such as a crystal resonator is previously fixed to a substrate (stem) 6 with lead-free solder. Next, a jig (tool) is set in the vacuum apparatus together with the lid (lid) 8 and the low-melting glass 9 to keep the high vacuum while reaching the melting point of the low-melting glass while raising the temperature, and the substrate (stem) 6 and the lid (lid). ) 8 is hermetically sealed to obtain a product.

Z: Glass Y: Alumina ceramic grains
1 : fired body of composite material 1: green sheet of composite material 2: internal conductor printing pattern 3: through hole 4: external conductor printing pattern 5: green sheet frame 6, 22 of composite material for storage space space: substrate (stem)
7, 55: Functional device such as a crystal resonator 8, 33: Lid
9, 44: Low melting point glass 2a, 2b, 22a, 22b for sealing: Internal conductor layers 4a, 4b: External conductor layers 2c, 22c: Conductive layers for connection

Claims (4)

  A thin plate substrate is made using an inorganic material composed of a composite material composed of glass and ceramic, and there are at least two or more independent metal copper conductors on the opposite parallel planes of the substrate. Are characterized in that they are connected independently of each other,   A substrate (stem) characterized in that it includes a window frame-like thin plate-like substrate and at least two locations independently of each other, wherein the conductors are present on at least one side of the substrate. ),   A substrate (stem) characterized by including a quartz crystal resonator or the like of a functional device fixed to a conductor portion provided on the substrate side of the window frame shape including the claim 1 and 2.   Claims 1, 2, and 3 are characterized in that the substrate (stem), a glass that secures an airtight space, and a lid (lid) made of an inorganic material made of a composite material made of ceramic are hermetically sealed. Airtight container and functional device,

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