JPH02138760A - Hermetically sealed package - Google Patents

Abstract

PURPOSE:To obtain a package which has no voids and no cracks between sheet layers at a low cost by a method wherein a mixture of glass powder and a alumina powder specified in composition is used for a base section when a hermetically enclosing package is composed of a cover section of a plate and a base section provided with a step part where an element is mounted. CONSTITUTION:A package is composed of a base section 8 and a cover section 16, an element such as an oscillator or the like is enclosed in an inner step section, and external electrodes 13 and others are fitted to the rear of the base section 8. In this constitution, the base section 8 is formed of a laminar green sheet of a mixture of glass powder and alumina powder, and the composition of the mixture is specified as follows: that is, 40-65wt.% of SiO2, 5-15wt.% of CaO, 10-25wt.% of PbO, 0.5-10wt.% of MgO, 0.1-10wt.% of Na2O, 0.1-10wt.% of K2O, 0-20wt.% of Al2O3, 0-10wt.% of B2O3, and 0-5wt.% of ZnO are contained in the mixture, and the mixture is formed into a slurry using an acrylic binder, and the laminar green sheet concerned is formed of the slurry through a doctor blade method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thin, hermetically sealed package for arrival, and particularly to a hermetically sealed wearable package suitable as a package for a surface-mounted crystal oscillator.

``Prior art'' Traditionally, crystal oscillators have been made by inserting a raw crystal into a crystal piece having the shape shown in Figure 1, and using the crystal piece as an element.
A tuning fork crystal oscillator used as a so-called vibrator 1 is known, and as shown in FIG. 2, the vibrator 1 is bonded to an electrode lead 3 fixed to an electrode support stem 2 using adhesive or solder. It has a structure in which a metal cab 4 is placed over the electrode support stem 2 so as to fix the vibrator 1 and hermetically seal the vibrator 1.

By the way, in this tuning fork type crystal oscillator, the metal cap 4 has a small diameter of about 1.5 IIm, and the length of the entire crystal oscillator is also small, about 5 m111, but in recent years various products using crystal oscillators have become smaller. As crystal oscillators become smaller and thinner, crystal oscillators themselves are also required to be smaller and thinner. The development of surface-mounted crystal oscillators, which can be made smaller and thinner than tuning-fork crystal oscillators, by mounting the rectangular oscillator on a printed wiring board or the like, is underway. As shown in FIG. 3, this surface-mounted crystal oscillator uses a package consisting of a cover part 5, which is a flat plate, and a base part 7, which has a stepped part on which a resonator 6 is mounted. , its base part 7
is formed by laminating three or more alumina sheets.

[Problems to be solved by the invention] However, the firing temperature of the alumina sheet is 1500~
The temperature is as high as 1600℃, and the wiring formed on it is made of Mo
It is necessary to use a material with a high melting point such as , W, etc. and to fire it in a reducing atmosphere, and the base part of the PASOCAGE made by laminating these materials has poor workability and increases manufacturing cost.

The present invention was made in view of the above circumstances, and can be manufactured at a lower cost and with better workability than conventional surface-mount crystal resonator packages using alumina sheets, and is thinner than alumina sheets. The purpose of this invention is to provide a thinner hermetically sealed wearable package.

[Means for Solving the Problems] The hermetically sealed package of the present invention is an airtight arrival package that is composed of a cover portion that is a flat plate and a base portion that has a stepped portion for mounting an element. The base part is characterized by being formed by laminating green sheets made by mixing glass powder and alumina powder.

Green Sea 1- used in the present invention has a weight percentage of 5i
0240~65%, CaO 5~15%, Pb010~
25%, Mg0 0.5-10%, Na2O1-10%
, 201~10°6, Al2030~20%, 820
It is characterized by consisting of 35-60% glass powder and 40-65% alumina powder with a composition of 30-10% ZnO (1-5%), and by laminating three or more of these green sheets, the base part of the package form.

The glass having the above composition is crystalline, and when mixed with alumina powder and fired, it reacts to form anorthite (Ca
A solid solution of n・^1□03・2SiO3) is precipitated.

The green sheet of the present invention, which is made by mixing such glass powder and alumina powder, can be made as thin as several tens of microns.
00 microns or more), it can be made considerably thinner. In addition, this green sheet has a firing temperature of 850~
ZnOMetals with low melting points, such as ^U, ^
It is possible to use materials such as g, Cu, ^g/Pd, etc. for the wiring, and it can be fired in air or in a nitrogen atmosphere, so it can be manufactured at a lower cost and with better workability than an alumina sheet.

The reason why each component of the glass of the green sheet used in the present invention is limited as described above is as follows.

When SiO□ is more than 65%, the softening point of the glass increases and molding becomes difficult, and when it is less than 40%, the amount of precipitated crystals is small and the strength of the package is reduced.

If the CaO content is more than 15%, crystallization becomes too strong and a dense material cannot be obtained, resulting in poor airtightness.If it is less than 5-6%, vitrification becomes difficult, and the amount of precipitated crystals is small, making it difficult to form a package. Strength decreases.

If PbO is more than 25%, the softening point of the glass becomes too low and deformation occurs easily during baking of the package.
(If it is less than 1%, vitrification becomes too difficult.

If Mg0 is more than 10%, it becomes difficult to melt the glass, and if it is less than 0.5%, a dense material cannot be obtained and airtightness deteriorates.

When Na2O is more than 10%, the insulation property decreases and 1
If it is less than %, the softening point of the glass increases and molding becomes difficult.

When 20 is more than 10%, the amount of precipitated crystals is small and the strength of the pass gauge is reduced, as well as the insulation properties are reduced.
If it is less than %, vitrification becomes difficult.

＾１□0． If the amount is more than 20%, the glass softens and becomes stiffer, making it difficult to mold.

If the B2O3 content is more than 10%, it is not preferable because the B2O3 component is easily released during firing and reacts with the conductor.

When 2nO is more than 5%, precipitation of crystals in the glass is suppressed.

The reason why the mixing ratio of glass powder and alumina powder in the green sheet of the present invention is limited to the base fertilizer is as follows.

In other words, the glass powder is 35% or less and the alumina powder is 65%.
% or more, the airtightness of the fired package decreases, and if the glass powder content is 60% or more and the alumina powder content is 40% or less, the strength of the package decreases.

The base portion of the hermetically sealed package of the present invention is produced as follows. First, glass powder is ground to a particle size of 5 microns or less, and this is mixed with alumina powder. This mixture is mixed with a binder resin and a solvent, and after fS, a sheet I with a thickness of 0.05 to 0.5 mm is formed using a doctor blade method. This sheet is then cut to a predetermined size, and wiring is screen printed. , layered three layers and heated to a temperature of 50~ZnO
℃ and a pressure of 50 to 150 kg/crn'', and then fired at 850 to 150 kg/crn''. Note that it is possible to screen print the same pattern of a plurality of wirings on the green sheet at once.

Further, it is preferable that the cover part is made of a flat glass plate and is transparent. That is, a weight is formed on the vibrator, which is an element, by vapor deposition or the like, but this weight can be evaporated by irradiating it with a laser. When transparent plate glass is used for the cover, a laser beam is irradiated onto the weight from the outside through the cover to change the weight of the weight, which allows the frequency of the crystal oscillator to be adjusted, resulting in more accurate crystal oscillation. This is because children can be created.

Although it is possible to use a ceramic flat plate as the cover part, glass is preferable in consideration of strength and airtightness7. [Example] The following is an example of an airtight wearable package of the present invention. FIG. 4 shows a cross-sectional view of a surface-mounted crystal oscillator using the hermetically sealed package of the present invention.

The base part 8 of the Pa-Socage is formed by laminating three layers of green sheets and bonding them under heat.The lower plate 9 and the middle plate 10 are made of ZnO micron thick, and the upper plate 11 is a green sheet of 400 micron thick. The dimensions of the base part after firing are: Ox3. Ox 0.4mm 1, this green sheet contains SiO□60% by weight percentage, C
aO8%, Pl+OI8%, Mg0 3%, Na2O3
%, 202% B2() and 36% B2() glass was prepared by mixing oxidized salt and carbonate into a platinum crucible, melted at about 1500°C for 1 hour, then crushed, and then alumina A glass powder with an average particle size of 2 microns was obtained by grinding with a ball mill, and this glass powder and alumina powder with an average particle size of 3 microns were mixed at a volume ratio of 45:55, and the ZnO weight of this mixture was 50 parts by weight of toluene, 12 parts by weight of an acrylic binder, and 1 part by weight of a plasticizer were kneaded to form a slurry, and then produced by a doctor blade method.

In addition, the base part 8 is made of this green sheet of 60 x 70 m.
Cut into m pieces and punch 24 holes according to the shape of each layer to form A
A conductor 12 made of g1Pd is screen printed on a predetermined surface of the middle plate](l, and an external electrode 13 is screen printed on a predetermined surface of the lower plate 9.
Each sheet is laminated at a temperature of +00℃, ZnO kg/
After thermocompression bonding for 1 minute under a pressure of
It was baked for 0 minutes and then cut into a predetermined size.

Wiring 14 is formed on both sides of the base portion 8, and the wiring 14 connects the external mold fII3 to the conductor 12 and the vibrator 15.
is connected to an excitation electrode formed on the surface of.

The base part 8 of the package 1 cage is hermetically sealed via a glass frill 17 using a cover part 16 made of a flat plate of transparent glass and having dimensions of 6, OX 3.0';< 0.3 nua. It is worn.

When the package thus produced was cut and its cross section was observed under a microscope, it was found that there were no pores or cracks between the layers, and the airtightness was good.

[Effects of the Invention] As described above, the hermetic sealing package of the present invention is superior to the conventional package for surface-mounted crystal resonators using alumina sheets.
It has better workability than socage and can be manufactured at a lower cost.

Note that the present invention is not limited to surface-mounted crystal oscillators, but can be applied to AT-cut crystal oscillators by changing the shape of each sheet and stacking them, and by changing the positions of electrodes, conductors, and wiring. It can also be used as a package, and can be applied to various applications as a parameter for elements that require hermetic sealing.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a crystal piece of a tuning fork type crystal oscillator, Figure 2 is a sectional view of a tuning fork type crystal oscillator, Figure 3 is a sectional view of a conventional surface mount type crystal oscillator, and Figure 4 is a bookmark. 1A and 1B show cross-sectional views of the surface-mounted crystal oscillation according to the invention.

Claims (2)

[Claims] (1) In a hermetically sealed package consisting of a cover part which is a flat plate and a base part having a stepped part for mounting an element, the base part is a green sheet made by mixing glass powder and alumina powder. An airtight wearable package characterized by being formed by laminating layers. (2) The green sheet has a weight percentage of SiO_240~
65%, CaO5-15%, PbO10-25%, Mg
O0.5-10%, Na_2O1-10%, K_2O1
~10%, Al_2O_30~20%, B_2O_30
Glass powder 3 with a composition of ~10%, ZnO 0~5%
The hermetically sealed wearable package according to claim 1, characterized in that the package is comprised of 5 to 60% alumina powder and 40 to 65% alumina powder.