JPH0365811A - Thin profile crystal vibrator - Google Patents

Abstract

PURPOSE:To improve the air-tightness and the productivity by using a ceramic material for a case and forming a leadless electrode. CONSTITUTION:An upper glass case 10 has a glass upper plate 12 and a swollen part 14 and made of non-gas transmitting glass, and a lower ceramic case 30 has a ceramic lower plate 32, a swollen part 34 and a projection 38 and made of non-gas transmitting ceramic. The lower ceramic case 30 has a conductor layer 42 formed to traverse the border between the lower plate and the swollen part of the case 30, and a leadless electrode 40 not having a lead wire is placed on the outer surface of the lower ceramic case 30. Then the crystal vibrator 20 and the leadless electrode 40 are connected electrically with a conductive material 44 packed in a hole 36 provided to the conductor layer 42 and the lower ceramic case. Thus, porosity is improved and the surface mount is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crystal resonator with ultra-thin leadless electrodes using a ceramic case having a top plate with excellent light transmittance.

[Conventional technology]

In recent years, demands for electronic components to be smaller, thinner, and more reliable have been increasing. Among these, there is a particularly strong demand for smaller and thinner crystal units for electronic wristwatches, IC cards, and memory cards. For example, the thickness of an IC card is specified as 0.76 flI in the I80 standard,
The thickness of the crystal oscillator built into the card is 0.5
*It is necessary to be less than or equal to yx. In addition, with recent advances in surface mount technology in the field of electronic component mounting, electronic components are rapidly becoming leadless, and electronic devices are becoming smaller and thinner due to high density mounting using surface mount technology. is being developed.

Traditionally, quartz crystal resonators have characteristics that fluctuate due to factors such as humidity, so a crystal oscillator processed from a single crystal is used in a case (
c), the crystal vibrating body is electrically connected to an electrode on the outside of the case, and the inside of the case is kept in a vacuum, for example.

Conventional crystal resonators are housed in a cylindrical metal case and have lead wires that connect the external electrical circuit to the crystal resonator, making it difficult to make them smaller and thinner, and surface mounting is required. The disadvantage was that it was not suitable for Furthermore, sealing glass is used to seal between the lead wire and the metal case, but the airtightness between the sealing glass and the lead wire or metal case deteriorates. In some cases, a problem of changes in oscillation frequency characteristics may occur.

Further, the crystal vibrating body housed in the internal space formed by the upper plate, the lower plate, and the two glass cases required a lead wire in order to be electrically connected to an external electric circuit.

For example, a thin crystal resonator disclosed in Japanese Unexamined Patent Publication No. 56-69917 has a structure in which the crystal vibrator is sandwiched between containers, and has a holding frame that is integral with the crystal vibrator and surrounds it. A crystal resonator with this structure has electrodes attached to the crystal resonator located inside the container, and requires wiring to connect these electrodes to an external electric circuit.
It was not suitable for surface mounting.

Furthermore, a crystal resonator has been proposed in which a crystal resonator is housed in an internal space formed by joining two ceramic cases having recessed portions.

In a crystal resonator having this shape, the crystal resonator and an external electric circuit are connected using lead wires, or electrodes are provided on the outer surface of the case, and the electrodes and the crystal resonator are electrically connected. In the former case, there is a problem that it is not suitable for surface mounting. In the latter case, a through hole is provided in the ceramic case and electrical connection is made by filling the through hole with, for example, a conductive adhesive. There were problems such as a decrease in sexual performance.

Furthermore, in the crystal resonator production process, after the crystal resonator is installed in the same number as the case, performance inspection and fine adjustment such as frequency adjustment are performed, and at that time, a capacitor for frequency fine adjustment is specially installed. This is one of the reasons why the productivity of crystal resonators is not good as they are forced to do extremely complicated work.
I'm getting stumped. In addition, there is a problem in that the crystal resonator becomes even larger and thicker in this process.

[Problem that the invention seeks to solve]

In order to accommodate the crystal oscillator, there must be a minimum gap of approximately 0.05 m between the top and bottom surfaces of the quartz crystal oscillator installed horizontally inside the case and the case in the internal space i of the case. It is said that If the gap is narrower than this, the oscillation frequency characteristics of the crystal resonator will deteriorate. Therefore, in order to have a certain internal space and reduce the total thickness of the crystal resonator, it is necessary to reduce the thickness of the kennis itself in the portions facing the top and bottom surfaces of the crystal resonator. However, it is important to maintain sufficient airtightness.

When using resin as the case material for a thin crystal resonator,
If the resin thickness of the case is made thinner in the portions of the case that face the upper and lower surfaces of the crystal resonator, problems such as a decrease in the mechanical strength of the crystal resonator and poor airtightness arise. When using metal for the case material, this problem does not occur, but instead it is necessary to provide an insulating layer to insulate the electrical connection part that connects the crystal resonator inside the case and the electrodes outside the case from the metal case. However, there is a problem in that the overall thickness of the crystal resonator cannot be reduced.

Crystal resonators having lead wires have a problem in that it is difficult to apply surface mounting technology, and they cannot respond to miniaturization and thinning of electronic components.

Furthermore, there is a problem in that the reliability of the crystal resonator decreases due to the deterioration of the airtightness between the lead wire and the case.

In order to connect the crystal oscillator and the electrodes on the outside of the case,
When a through hole is provided in the case and a conductive adhesive is filled in the through hole, there is also the problem that the reliability of the crystal resonator is lowered due to deterioration of airtightness between the conductive adhesive and the inner wall surface of the through hole.

Furthermore, in the process of adjusting the frequency of the crystal resonator at the manufacturing stage, a frequency adjustment capacitor and the like are further installed. In this case, there is a problem that not only the vibrator becomes large and thick, but also productivity is extremely reduced.

The present invention has been made to solve the above problems all at once.

[Means to solve the problem]

The present invention provides: (a) an upper plate that is impermeable to gas and has excellent light transmittance; a lower ceramic plate that is impermeable to gas; and a gas evaporator provided around at least one of the upper plate and the lower plate. a ceramic case having an internal space formed by overlapping the upper plate and the lower plate through the raised parts and hermetically sealing them; b) a crystal vibrating body fixed in a vibrating state in the internal space of the ceramic case; (C) a leadless electrode provided on the outer surface of the ceramic case; and (d) the raised portion or the raised portion. and a conductive layer for electrically connecting the crystal vibrating body and the leadless electrode, the conductor layer being formed to cross the boundary direction between the crystal vibrating body and the leadless electrode.

[For production]

By using ceramic materials for the case of a crystal resonator, it is possible to create a case that is thin but has high mechanical strength and excellent airtightness. Furthermore, by forming leadless electrodes, a surface-mountable crystal resonator can be manufactured.

Furthermore, since the conductor layer is formed between the ceramic upper or lower plate and the raised portion or buried inside the raised portion, it is possible to prevent the conductor layer from being airtight from the surroundings.

In addition, by using glass with excellent light transmittance for the upper plate, frequency adjustment in the production process can be easily achieved by simply irradiating laser light such as YAG, and there is no need to install a special frequency adjustment capacitor. As a result, a smaller, thinner, and highly accurate crystal resonator can be obtained, and at the same time, productivity can be greatly improved.

[Example] Hereinafter, a thin crystal resonator using a ceramic case of the present invention will be described with reference to the drawings.

FIG. 1 is an exploded perspective view of a thin crystal resonator 10 of the present invention, and the thin crystal resonator 1 consists of an upper glass case 10, a crystal vibrating body 20, and a lower ceramic case 30. FIG. 2 is the person-to-person %B-B of the thin crystal resonator of the present invention in Figure 1.

It is an exploded sectional view along CC. Upper glass case 1
0 has a glass top plate 12 and a raised portion 14, and is made of non-gas permeable glass. The lower ceramic case 30 includes a ceramic lower plate 32, a raised portion 34, and a protrusion 38, and is made of non-gas permeable ceramic. The lower ceramic case 30 further includes a conductive layer 42 formed across the interface between the lower plate of the case 300 and the raised portion. A leadless electrode 4° without a lead wire is installed on the outer surface of the lower ceramic case 30. The crystal vibrating body 20 and the leadless electrode 40 are electrically connected by a conductive material 44 filled in a conductive layer 42 and a hole 36 provided in the lower ceramic case.

The upper glass case 10 is obtained by forming a portion that will become the raised portion 14 on the glass upper plate 12.

The glass used for the upper glass case 10 and the glass plate 12 may be any glass that can efficiently transmit the laser beam used for frequency adjustment, such as YAG. It is a glass described in pages 516 to 518 of "Chemistry Dictionary 2" [June 15, 1960, first edition, second printing, published by Kyoritsu Shuppan ■], and more specifically, for example, oxide glass.

Examples include fluoride glass, chloride glass, sulfide glass, carbonate glass, nitrate glass, sulfate glass, hydrogen bond glass, and elemental glass, among which oxide glass is preferred. Examples of oxide glasses include silicate glasses,
There are phosphate glasses and borate glasses, among others,
A silicate glass mainly composed of silicate having a high melting temperature and good light transmittance is preferred.

The lower ceramic case 30 is constructed by screen-printing a screen-printable conductive paste on a ceramic green sheet that will become the ceramic lower plate 32 after firing to form a conductor layer 42; A shaped ceramic is screen printed to form the portions that will become the raised portions 34 and protrusions 38 after firing, as well as the holes 36. Next, the portions that will form the leadless electrodes 40 are screen printed with a conductive paste ζ trowel. Obtained by firing.

The green sheet used to form the lower ceramic case is made of alumina, aluminum nitride, mullite, or the like. The conductive paste forming the conductor layer 42 is W, Mo, Ag.
It is made of s P t s Au s , Cu, etc., and its characteristics are desirably good matching with the green sheet, such as adhesion with the green sheet and no cracking after firing, and this conductive paste is Screen printing is performed one or more times to form a conductive layer. Further, the paste-like ceramic is made of alumina, aluminum nitride, mullite, etc., and preferably has the same shrinkage characteristics as the green sheet.

To form the ridges, paste alumina is screen printed one or more times. The conductive paste forming the leadless electrode 40 is W, Mo,
It is made of Ag, Pt, Au%Cu, etc., and it is desirable that it has good matching properties with the green sheet.This conductive paste is screen printed once or multiple times to form a leadless electrode. The firing conditions vary depending on the green sheet, conductive paste, and paste-like ceramic used, but it is generally desirable to fire at 800 to 2000°C in a reducing atmosphere or vacuum.

The upper glass case 10, the crystal resonator 20, and the lower ceramic case 30 have the holes 36 filled with a conductive adhesive 44,
The crystal vibrating body 20 is connected to the raised portion 3 of the lower ceramic case 30.
4 and the protrusions 38, the crystal vibrating body 20 and the conductive layer 42 are brought into contact with the conductive adhesive 44, which is a conductive material, and the conductive adhesive 44 is cured, and the crystal vibrating body 20 is attached to the raised part. After fixing it on top of 34, the upper glass case 10
and the lower ceramic case 30 with respective raised portions 14 and 3.
4 and hermetically sealed. Hermetic sealing can be achieved by various methods such as melting solder under vacuum or melting glass. The conductive adhesive is made of silver-polyimide resin, silver-epoxy resin, etc., and the curing condition is preferably higher than the hermetic sealing temperature.

Since the lower ceramic case is provided with the protrusion 38, it has the effect of preventing the ceramic case from warping or twisting after firing.

FIG. 3 is another embodiment of the invention. Unlike the embodiment shown in FIG. 2, in FIG. 3 the upper ceramic case 10 does not have a raised portion. Instead, the raised portions of the lower ceramic case 30 have two stages of 34 and 34B, and the crystal vibrating body 20 can be fixed on the raised portions 34 and the protrusions 38. The upper ceramic case 10 and the lower ceramic case 30 can be hermetically sealed via the raised portion 34B. The configuration of other parts is the same as in FIG. 2.

FIG. 4 shows yet another embodiment of the invention.

Similar to the embodiment shown in FIG. 3, in FIG. 4, the upper glass case 10 does not have a raised part, and the raised part of the lower ceramic case 30 has two stages of 34 people and 34B. Therefore, the crystal vibrating body 20 can be fixed on the raised portion 34A. The difference from FIG. 3 is that the conductor layer 42 is
There is a hole 36 formed between the person and the raised part 34B across the raised part, and there is no hole 36 in the raised part 34A. The conductive layer 42 and the crystal vibrating body 2 are bonded together using a conductive adhesive.
0 are electrically connected, and the crystal vibrating body 42 is fixed on the raised portion 34. In other respects, the crystal resonator shown in FIG. 4 is similar to the crystal resonator shown in FIG. 3.

The total thickness of the crystal unit after assembly is preferably 0.3
~0.5was. Because it is difficult to manufacture extremely thin upper glass cases and lower ceramic cases, it is difficult to manufacture crystal resonators with a total thickness of less than 0.3 m, and crystal resonators with a total thickness of more than 0.51 m are difficult to manufacture. cannot be incorporated into an IC card. Preferably, the thickness of the ceramic top and bottom plates is each 0.05 to 0.2 vI. The thickness of the ceramic upper and lower plates is 0.04 El
Below that, gas impermeability is poor. In addition, if the total thickness of the crystal unit is 0.2n or more, if the total thickness of the crystal unit is 0.5 WM or less, the gap between the crystal unit and the ceramic upper or lower plate in the internal space of the ceramic case will not be sufficient. , the oscillation frequency characteristics of the crystal oscillator are adversely affected. The thickness of the crystal vibrating body used is 0.05 to 15
IIs is particularly preferably 0.09 to 0.151111. The vibration mode of the crystal vibrating body is preferably a tuning fork type.

〔effect〕

Since the thin crystal resonator of the present invention uses a ceramic case, it has sufficient mechanical strength even with a total thickness of 0.3 m and is excellent in airtightness.

In addition, the crystal impedance of the vacuum-sealed crystal resonator is usually less than 80Ω, and depending on the conditions, less than 50Ω, which is an excellent characteristic, and since it is a leadless electrode, surface mounting is easy. Furthermore, it is possible to obtain a highly reliable crystal resonator with excellent airtightness between the ceramic case and the conductor layer that electrically connects the leadless electrode and the crystal resonator.

In addition, by using glass with excellent light transmittance (6ζ) for the top plate, frequency adjustment in the production process can be easily achieved by simply irradiating a laser beam such as YAG, and a special frequency adjustment capacitor can be installed. This eliminates the need for this, making it possible to obtain a smaller, thinner, and more accurate crystal resonator, and at the same time, productivity can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a thin crystal resonator of the present invention. FIG. 2 is an exploded sectional view taken along the A-entry line, the B-B line, and the C-C line in FIG. 3 and 4 are exploded sectional views of another embodiment of the thin crystal resonator of the present invention. In the figure, 1 is a crystal resonator, 10 is an upper glass case, 12
is a glass top plate, 14.34.34 people and 34B are raised parts, 20 is a crystal vibrating body, 30 is a lower ceramic case, 3
2 is a ceramic lower plate, 38 is a projection, 40 is a leadless electrode, and 42 is a conductor layer. Figure 2 Figure 3

Claims (2)

[Claims] (1) (a) A gas-impermeable upper plate with excellent light transmittance, a gas-impermeable ceramic lower plate, and a gas-impermeable gas shield provided around at least one of the upper plate and the lower plate. (b) a ceramic case comprising a raised part of a transparent ceramic and having an internal space formed by overlapping the upper plate and the lower plate via the raised part and hermetically sealing the same; (c) a leadless electrode provided on the outer surface of the ceramic case; (d) the raised portion or the raised portion and the upper surface thereof; A crystal resonator comprising: a conductive layer for electrically connecting the crystal vibrating body and the leadless electrode, the crystal vibrating body being formed across an interface with a plate or a lower plate. (2) The thickness of the upper plate and the lower plate other than the raised portions is 0.
05~0.2mm, and the total thickness of the crystal resonator is 0.3~0.2mm.
The crystal resonator according to claim 1, which has a diameter of 0.5 mm.