GB2130005A - Encapsulated piezoelectric resonator - Google Patents
Encapsulated piezoelectric resonator Download PDFInfo
- Publication number
- GB2130005A GB2130005A GB8328544A GB8328544A GB2130005A GB 2130005 A GB2130005 A GB 2130005A GB 8328544 A GB8328544 A GB 8328544A GB 8328544 A GB8328544 A GB 8328544A GB 2130005 A GB2130005 A GB 2130005A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tube
- glass
- resonator
- pins
- ball
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000011521 glass Substances 0.000 claims abstract description 26
- 239000000853 adhesive Substances 0.000 claims abstract description 9
- 230000001070 adhesive effect Effects 0.000 claims abstract description 9
- 239000000463 material Substances 0.000 claims abstract description 8
- 239000003822 epoxy resin Substances 0.000 claims abstract description 6
- 229920000647 polyepoxide Polymers 0.000 claims abstract description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 8
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims 2
- 229910052742 iron Inorganic materials 0.000 claims 1
- 229910052759 nickel Inorganic materials 0.000 claims 1
- 238000007789 sealing Methods 0.000 abstract description 2
- 239000002184 metal Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 238000000034 method Methods 0.000 description 5
- 229910000640 Fe alloy Inorganic materials 0.000 description 3
- 229910000990 Ni alloy Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005538 encapsulation Methods 0.000 description 3
- 229910000833 kovar Inorganic materials 0.000 description 3
- 229910000531 Co alloy Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/10—Mounting in enclosures
- H03H9/1007—Mounting in enclosures for bulk acoustic wave [BAW] devices
- H03H9/1014—Mounting in enclosures for bulk acoustic wave [BAW] devices the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the BAW device
- H03H9/1021—Mounting in enclosures for bulk acoustic wave [BAW] devices the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the BAW device the BAW device being of the cantilever type
-
- G—PHYSICS
- G04—HOROLOGY
- G04F—TIME-INTERVAL MEASURING
- G04F5/00—Apparatus for producing preselected time intervals for use as timing standards
- G04F5/04—Apparatus for producing preselected time intervals for use as timing standards using oscillators with electromechanical resonators producing electric oscillations or timing pulses
- G04F5/06—Apparatus for producing preselected time intervals for use as timing standards using oscillators with electromechanical resonators producing electric oscillations or timing pulses using piezoelectric resonators
- G04F5/063—Constructional details
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/02—Containers; Seals
- H01L23/06—Containers; Seals characterised by the material of the container or its electrical properties
- H01L23/08—Containers; Seals characterised by the material of the container or its electrical properties the material being an electrical insulator, e.g. glass
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
In order to simplify closure thereof, the casing of the resonator comprises a tube (2) which is preferably of glass and a glass ball (4) through which conductive pins (6, 8) are sealed. The ball (4) is sealed into the open end of the tube (2) by a sealing ring (18) of organic adhesive material, preferably an epoxy resin. If the tube (2) is also of glass, the frequency of the resonator may be adjusted by use of a laser after the resonator has been fitted into the casing. <IMAGE>
Description
SPECIFICATION
Encapsulated piezoelectric resonator
The present invention concerns an encapsulated piezoelectric resonator of the type which is used in particular in electronic watches.
It is well known that, nowadays, in electronic watches, whether they are of the digitial display type or the analog display type, the time base comprises a piezoelectric resonator which in most cases is of quartz, of a tuning fork configuration. The resonator is excited to vibrate in a flexural mode, producing a signal whose frequency is in most cases close to 32768 Hz.
That signal is applied to division stages to produce the time information pulses.
The most widespread form of casing for such resonators is cylindrical. The casing is formed by a cylindrical tube which is plugged at its open end by a body of insulating material which is sealed into the tube. Pins pass through this body for the supply of electrical power to the resonator and the output of the frequency signal. In most cases, the pins also act to support the tuning fork. The tube is generally made of metal. However, the production of the seal between the tube and the plugging body requires a series of complicated operations.
The plug body comprises a ring of the alloy known under the Trademark KOVAR in which a glass pellet is formed, the pins being embedded in the glass pellet. In addition, metal layers have to be formed on the outside surface of the ring and on the inside surface of the tube and the components must be of very accurate dimensions in order to provide for fixing the body to the tube by forcing the body into the open end of the tube and forming a metal-to-metal seal.
Another disadvantage of such an arrangement is that the tuning fork must be frequency-tuned before it is encapsulated. Final frequency tuning of the resonator is in most cases effected by laser bombardment of metal layers which are provided for that purpose at the ends of the tines of the tuning fork. It will be clear that, in order to be able to use such a procedure after the tuning fork has been encapsulated, the casing must have at least one part which permits the laser beam to pass therethrough. This cannot be done in the case of metal casings. In addition, it is well known that, in order for the tuning fork to be capable of being excited under acceptable electrical consumption conditions, the tuning fork must be enclosed in a sealed chamber, within which a hard vacuum is formed. The ambient pressure in which the resonator vibrates defines its quality factor, 0.The higher the pressure, the lower the quality factor.
In order to permit adjustment of the frequency after encapsulation of the tuning fork, Japanese
Patent Publication No. 55-78017 proposes making the cylindrical casing of glass. The tuning fork is mounted on the ends of the connecting pins and is introduced into the casing which is open at one of its ends. Heating is applied to fuse the open end of the casing round the pins, in order to produce a sealed closure. Such a process is difficult to control in practical production and the mechanical fixing of the pins is not very satisfactory.
The object of the present invention is to provide an encapsulated piezoelectric resonator in which closure of the casing can be effected in a reliable fashion, using processes which are simple to carry into effect.
According to the present invention there is provided an encapsulated resonator comprising a cylindrical tube which is closed at one end and plugged at the other by a glass body of substantially spherical shape with a diameter which is slightly less than that of the tube, a ring of organic adhesive material which at least partially fills the annular region defined by the inside surface of the tube and the outside surface of the glass body and which adheres to these two surfaces to provide a fluid-tight seal between the tube and the glass body, two conductive pins which pass in sealed manner through the glass body, and a piezoelectric resonator which is disposed inside the tube and is fixed to the ends of the pins.
According to a development of the invention the tube is of glass. This permits fine adjustment of the frequency of the resonator, after encapsulation thereof.
Preferably, the adhesive material is an epoxy resin. Preferably also, the pins are made from an alloy of iron and nickel which enjoys good adhesion to the glass or preferably again the pins are made from the material which is known under the Trademark KOVAR, being an alloy of iron, nickel and cobalt.
The invention will be described in more detail, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a view in longitudinal section of the tube of a resonator embodying the invention,
Figure 2 is a view in longitudinal section of the plug body provided with the pins on which the tuning fork is mounted, and
Figure 3 is a partial view in longitudinal section of an encapsulated resonator embodying the invention, more particularly showing the manner of sealing the plug body into the tube.
Referring firstly to Figure 1, it will be seen that the tube 2 comprises a cylindrical portion 2a which is closed at one of its ends by a hemispherical portion 2b and which is open at its other end, so as to define a circular opening 2c. The tube is of glass and it may be 6.2 mm in length, with an inside diameter of 1.20 mm and an outside diameter of 1.60 mm. The glass used may be of the type marketed by Corning under the reference 747.01 or 747.50.
Referring now to Figure 2, it will be seen that the plug body for the tube is formed by a substantially spherical member 4, the diameter of which is slightly less than the inside diameter of the tube 2, it is for example 1.10 mm. Two parallel conducting pins 6 and 8 pass through the spherical plug body or ball 4. The diameter of the pins 6 and 8 is for example 0.2 mm. Each pin has an external end portion 6a, 8a and an internal end portion 6b, 8b.
An advantageous process for producing the ball 4 with its pins 6 and 8 comprises forming the ball on the appropriate part of the pins, from a sintered glass powder. In addition, if the pins are made of a metal which enjoys good adhesion to the glass, the pin-ball joint will be a perfectly sealed joint.
For that purpose, the pins 6 and 8 may be made of an iron-nickel alloy. A particularly advantageous alloy is an alloy of iron, nickel and cobalt, which is known by the Trademark KOVAR.
After the ball-pin assembly has been formed, a resonator 10, for example a tuning fork, is fixed to the internal end portions 6b and 8b of the pins 6 and 8. That process is very well known and there is therefore no need for it to be described in greater detail herein. It will be simply pointed out that the tuning fork has a base portion 1 Ob on which there are two conducting regions 1 2a and
1 2b which are suitably connected to the different
electrodes 14 disposed on the tines of the tuning fork. The tuning fork is for example bonded to the
internal end portions of the pins by means of a conductive epoxy resin which at the same time forms the electrical connection between the pins and the conducting regions 1 2a and 1 2b.
The glass used for the ball 4 may again be of the type marketed by Corning under the reference 474.01 or 747.50.
The assembly shown in Figure 2 is then fitted in the tube 2 shown in Figure 1. For that purpose, the tuning fork and the ball 4 are introduced into the tube in such a way that the central section A At of the ball 4, in a plane perpendicular to the pins 6 and 8, is within the open end or mouth 2c of the tube 2. The inside cylindrical surface 2d of the
mouth of the tube and the outside spherical surface 4a of the ball thus define an outwardly directed annular region 16. To form the seal, a drop of adhesive is deposited in the region 16. The adhesive is an epoxy resin which has good
adhesion to the glass. Preferably, the resin used is that known as "Hysol (RTM) E01 016". A pumping
operation is carried out to form a hard vacuum within the tube 2 and that assembly is locally
heated.The viscosity of the adhesive material forms an annular band 18 around the whole of the
periphery of the ball, as shown in Figure 3. By
polymerising the ring of adhesive material 18 by
heating, the ball 4 is hermetically sealed in the
mouth of the tube 2. When a sufficient degree of polymerisation has been obtained, the pumping action is stopped.
It will be readily appreciated that the wedging effect produced by the co-operation of the outside spherical surface of the ball and the inside cylindrical surface of the mouth of the tube promotes distribution of the resin over the whole of the periphery of the arrangement. Thus, the interior 20 of the tube maintains the vacuum.
When there is no need to effect frequency tuning of the resonator, with a high degree of precision, it is possible for the glass tube to be replaced by a conventional metal cap. The epoxy resin adheres to the cap and to the glass ball in the same way.
It will be apparent from the foregoing description that the invention in fact makes it possible to produce a resonator which is encapsulated in a casing which may be transparent and which is very well sealed. In addition, the steps involved in producing the encapsulation are relatively simple to carry out. It should be noted in particular that there is no need for any machining of the ball 4 in order to produce a high-quality seal.
Claims (4)
1. An encapsulated resonator comprising a cylindrical tube which is closed at one end and plugged at the other by a glass body of substantially spherical shape with a diameter which is slightly less than that of the tube, a ring of organic adhesive material which at least partially fills the annular region defined by the inside surface of the tube and the outside surface of the glass body and which adheres to these two surfaces to provide a fluid-tight seal between the tube and the glass body, two conductive pins which pass in sealed manner through the glass body, and a piezoelectric resonator which is disposed inside the tube and is fixed to the ends of the pins.
2. A resonator according to claim 1 , wherein the tube is of glass.
3. A resonator according to claim 1 or 2, wherein the organic adhesive material is an epoxy resin.
4. A resonator according to claim 1, 2 or 3, wherein the pins are made of an alloy comprising at least iron and nickel and which adheres to the glass.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH654082 | 1982-11-10 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8328544D0 GB8328544D0 (en) | 1983-11-30 |
| GB2130005A true GB2130005A (en) | 1984-05-23 |
| GB2130005B GB2130005B (en) | 1986-02-05 |
Family
ID=4311205
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8328544A Expired GB2130005B (en) | 1982-11-10 | 1983-10-26 | Encapsulated piezoelectric resonator |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2130005B (en) |
| HK (1) | HK24787A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2566601A1 (en) * | 1984-06-22 | 1985-12-27 | Ebauchesfabrik Eta Ag | ASSEMBLY COMPRISING AN ENCAPSULATED PIEZOELECTRIC RESONATOR AND AN ASSOCIATED INTEGRATED CIRCUIT |
| GB2171248A (en) * | 1985-02-14 | 1986-08-20 | Tung Kung Chao | A manufacturing method on quartz crystal in glass casing by means of laser to weld and to adjust the frequency thereof |
-
1983
- 1983-10-26 GB GB8328544A patent/GB2130005B/en not_active Expired
-
1987
- 1987-03-19 HK HK24787A patent/HK24787A/en unknown
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2566601A1 (en) * | 1984-06-22 | 1985-12-27 | Ebauchesfabrik Eta Ag | ASSEMBLY COMPRISING AN ENCAPSULATED PIEZOELECTRIC RESONATOR AND AN ASSOCIATED INTEGRATED CIRCUIT |
| EP0167055A1 (en) * | 1984-06-22 | 1986-01-08 | Eta SA Fabriques d'Ebauches | Assembly comprising an encapsulated piezoelectic resonator and an associated integrated circuit |
| GB2171248A (en) * | 1985-02-14 | 1986-08-20 | Tung Kung Chao | A manufacturing method on quartz crystal in glass casing by means of laser to weld and to adjust the frequency thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8328544D0 (en) | 1983-11-30 |
| GB2130005B (en) | 1986-02-05 |
| HK24787A (en) | 1987-03-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 711A | Proceeding under section 117(1) patents act 1977 | ||
| PCNP | Patent ceased through non-payment of renewal fee |