JP3926002B2 - Piezoelectric vibrator and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a configuration of a piezoelectric vibrator such as a quartz vibrator and a manufacturing method thereof.
[0002]
[Prior art]
A typical structure of a conventional piezoelectric vibrator such as a quartz vibrator is shown in FIGS. FIG. 10 is a perspective view of a known structural example having a cylindrical container, partly broken away. The quartz crystal vibrating piece 1 has excitation electrode film electrodes 11 on both sides thereof, and the quartz lead electrode 12 is soldered to two lead wires penetrating the glass portion of the airtight terminal 91. A cap 92 is press-fitted in a vacuum to a hermetic terminal 91 whose outer periphery is coated with a soft metal to form an airtight container having a vacuum inside.
[0003]
FIG. 11 shows a structure of another known conventional example having a box-shaped container, and is a perspective view partially broken. The hermetic container is composed of a ceramic lower case 93 and a lid 95 (a metal plate or a glass plate having a metal plating applied to the periphery of the lower surface) soldered to the metallized edge portion on the upper surface thereof. Yes. One end of the quartz crystal resonator element 1 is placed on the lower case stepped portion 94 and connected and fixed by the conductive adhesive 41 so that the free vibration is not hindered. A through hole (not shown) (filled with a brazing material for airtightness) is provided under the conductive adhesive 41 and is electrically connected to the side electrode 96 serving as a terminal of the piezoelectric vibrator.
[0004]
In common with these conventional examples, in order to maintain the degree of vacuum in the container, a metal material or an inorganic material is used as the container or a sealing material. Inorganic materials such as glass and ceramic used for containers are brittle and easily broken and have poor workability. Basically, they are manufactured one by one, and are not truly desirable in mass production.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to eliminate the above-mentioned drawbacks of the piezoelectric vibrator having the conventional configuration, to reduce the cost while maintaining the performance by using an organic material as the material of the container, and to maintain the thin, small, and lightweight characteristics. By providing a structure of a piezoelectric vibrator that is improved and further suitable for SMD mounting, and enables processing up to immediately before the final process while connecting a large number of containers of, for example, 100 to 1,000 units, It is an object of the present invention to provide a method for manufacturing a piezoelectric vibrator that achieves further cost reduction.
[0006]
[Means for Solving the Problems]
(1) A lower case made of a substantially flat resin material in which the upper surface excluding the immediate vicinity of a predetermined number of through holes is covered with a metal layer and the lower surface is provided with terminal electrodes connected to the lower surface side of the through holes. An intermediate frame that is fixed to the upper surface of the lower case, has an intermediate frame through hole at a position corresponding to the through hole, and has a metallized surface that surrounds the intermediate frame through hole on the lower surface and is joined to the metal layer ; A piezoelectric vibrating piece fixed to the upper surface of the middle frame and having excitation electrodes individually connected to the upper surface side of the middle frame through-hole by solder or conductive adhesive, and a peripheral portion of the metal layer on the upper surface of the lower case is attached to cover hermetically the piezoelectric vibrating piece, the inner surface is made more and lid with a metal portion on at least peripheral lower surface with a metal or an inorganic material, printed wiring the lower case which stuck on at least the upper surface of the copper foil The substrate has a raw material in the abovementioned frame piezoelectric vibrator, wherein forming Rukoto a ceramic material.
(2) A step of forming a single large number of middle frames each having a middle frame through hole and having a metallized surface surrounding the middle frame through hole on the lower surface, and a predetermined directionality and interval between the middle frame on the surface of the jig plate A predetermined metal pattern that covers the upper surface excluding the immediate vicinity of the through hole provided at a position corresponding to the arranged middle frame through holes with a copper foil and the lower surface is connected to the through hole. Forming a lower case assembly having a shape in which a large number of lower case elements made of a printed wiring board are processed in close contact with each other and a plurality of lid elements formed at positions corresponding to the arrangement of the lower case elements Forming a lid assembly formed by mutually connecting, a step of overlapping and joining the lower surface of the middle frame arranged on the jig plate and the upper surface of the lower case assembly, and the individual middle frames Provide a piezoelectric vibrating piece on the top surface of The step of connecting the excitation electrode of the piezoelectric vibrating piece to the through hole, and the lower case assembly on which the piezoelectric vibrating piece is mounted and the lid assembly are aligned and overlapped. Forming a large number of piezoelectric vibrators in which case elements and lid elements are simultaneously bonded and connected, and cutting and separating the connected piezoelectric vibrators to obtain individual piezoelectric vibrators. A method for manufacturing a piezoelectric vibrator.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a three-plane view showing the structure of a crystal resonator as an example of an embodiment of the present invention, in which (a) is a plan view with a part of a lid broken, (b) is a central sectional view thereof, (C) is a bottom view. 2, 3 and 4 are two-side views for explaining the main components of the vibrator. FIG. 2 shows a crystal vibrating piece, FIG. 3 shows an inner frame, and FIG. 4 shows a lower case. ) Is a plan view, and (b) is a bottom view. The structure will be described with reference to these drawings.
[0008]
In FIG. 2, the quartz crystal resonator element 1 has excitation electrodes 11 such as a silver film formed on the upper surface and the lower surface by vacuum deposition or the like, and the crystal extraction electrode 12 therefrom is apparent in both FIGS. In this way, the end of the vibrating piece wraps around multiple surfaces and can be connected from both the upper and lower surfaces.
[0009]
In FIG. 3, reference numeral 7 denotes a ceramic inner frame having through holes at both left and right ends, and the upper and lower surfaces thereof end up with small circular electrode pads 74 which are metallized surfaces. On the lower surface is a metallized surface 73 surrounding the electrode pads. Although the frame shape is substantially rectangular, a triangular projecting portion 71 is provided at a diagonal position. This is a shape for discriminating between the front and back with different metallization patterns. The metallized surface is plated with another metal or solder as necessary.
[0010]
In FIG. 4, reference numeral 2 denotes a lower case made of resin. For example, a printed circuit board made of epoxy resin containing glass fibers with copper foils attached to the upper and lower surfaces is used as a raw material. As shown to (a), the copper foil part 21 is left on the whole surface, leaving both right and left ends on the upper surface. In addition, two through holes 24 are provided at a position where the crystal vibrating piece 1 is connected, and the inside of the hole is filled with a brazing material (solder material or a higher temperature brazing material) or the like in order to keep the container airtight. There is an exposed portion 27 of the resin material of the substrate in the immediate vicinity of the through hole 24, but the periphery is surrounded by the copper foil portion 21. Au flash plating is applied to at least the copper foil portion on the upper surface which becomes the inner surface of the hermetic container. Copper foil is left on the upper and lower surfaces of both ends of the lower case, and these are connected by copper plating formed on the entire side end surface to form the terminal electrode 26. This is connected to a through hole 24 led out to the lower surface by a lower surface extraction electrode 25 formed by etching a copper foil as shown in FIG. Resin-made printed circuit boards are suitable for reducing the size, thickness and cost of the structure.
[0011]
A method of assembling each component will be described with reference to FIGS. The middle frame 7 is placed on the lower case 2 such that the middle frame through hole 72 overlaps the through hole 24, and both are connected by heating and pressing with the high-temperature solder material 4. At the same time, the metallized surface 73 on the lower surface of the middle frame is connected to the copper foil portion 21 that spreads over the entire upper surface corresponding to the inner surface of the airtight container of the lower case except for the small area around the through holes. The high-temperature solder material 4 is preliminarily solder-plated by supplying a paste-like material to the upper surface of the lower case 2 and the lower surface of the middle frame 7 by a screen printing method or the like. The quartz crystal resonator element 1 is placed on the upper surface of the middle frame 7 so that the quartz lead electrode 12 overlaps the electrode pad 74 on the upper surface of the middle frame through hole 72 and is conductively bonded using a conductive adhesive or high-temperature solder. Is done. The portion of the crystal vibrating piece 1 that protrudes into the hole of the middle frame 7 freely vibrates. The assembling sequence may be such that the lower case 2 and the middle frame 7 are bonded first, and then the crystal vibrating piece 1 is mounted, or the crystal vibrating piece 1 is first mounted on the lower middle frame 7. You may join with a case. The lid 3 is formed by drawing a metal plate such as Kovar or copper and plated as necessary (for prevention of whisker generation and ease of brazing, Ni, Sn, solder, Au flash plating, etc. The lower edge is brazed to the peripheral edge portion of the copper foil portion of the lower case 2 by the encapsulated solder material 5. By carrying out this process in a vacuum, a crystal resonator in which the inside of the container is vacuum is completed.
[0012]
The airtightness of the container in this embodiment will be examined. The organic material itself constituting the lower case is more permeable to air and moisture than inorganic materials and metal materials. However, most of them are blocked by the copper foil portion 21 and the copper plating portion 23 that hit the inner surface of the container. The outside air that has permeated through the small-sized case material exposed portion 27 around the through hole 24 is the brazed portion of the high-temperature solder material 4 between the middle frame 7 and the metallized surface 73 and the copper foil portion 21 that are inorganic materials. Completely blocked. Next, the mountability is examined. If the solder reflow temperature is set to 240 ° C., for example, the brazing temperature of the encapsulated solder material 5 is, for example, 300 to 340 ° C., and the brazing temperature of the high-temperature solder material 4 is, for example, 360 to 400 °. Set to C. If these conditions are given, the user can mount the crystal resonator as an SMD component on the circuit board simultaneously with other electronic components.
[0013]
Next, an example of a process for manufacturing the crystal resonator of this embodiment in an assembled state will be described. FIG. 5 is a plan view showing a use state of the middle frame aligning jig 8. Positioning pins 81 are implanted at two corners of the jig plate. Ceramic is prone to deformation and cracking during processing, so it is manufactured as a single unit. A large number of middle frames 7 are randomly supplied onto the jig 8 and are vibrated. Some of them fit into the pin 82 for the middle frame planted at a height slightly lower than the thickness of the middle frame 7 so as to be inscribed in the inside of the middle frame, and fit in the correct position with the lower surface facing up. Close contact with the bottom of the. Those that are not placed correctly, such as those that are turned upside down, are lifted by the action of the middle frame pin 82 and can be easily removed. If this is repeated several times, the middle frame is aligned and set at all predetermined locations on the jig.
[0014]
FIG. 6 is a plan view of the high-temperature solder sheet assembly 40 in which the high-temperature solder material 4 is formed into a thin sheet having a required size and connected in a large number at predetermined positions. Positioning holes 201 are provided at the corners.
[0015]
FIG. 7 is a plan view of the lower case assembly 20. The lower case assembly 20 is a large printed circuit board in which a large number of elements of the lower case 2 are arranged vertically and horizontally, and copper foil is pasted on both sides in advance, and etching processing of the upper and lower surface patterns is performed. A long hole 202 and a through hole 24 are provided. Copper plating is applied to the inside of the through hole 24 and the inner surface of the long hole 202, and Au flash plating is applied to the entire surface of the copper. In addition, positioning holes 201 for aligning the aggregates are provided at the diagonal portions. First, the positioning holes 201 of the high-temperature solder sheet assembly 40 and then the positioning holes 201 of the lower case assembly 20 are inserted into the positioning pins 81 of the middle frame aligning jig 8, and are sandwiched by other jigs and pressed and heated. In this case, the middle frame is correctly placed on the lower case 2. Further, the crystal vibrating piece 1 is fixed to the assembly. The quartz crystal vibrating piece 1 is arranged in advance on a tray or the like, picked up one by one, placed on the inner frame 7 supplied with the conductive adhesive, heat treated, and frequency adjusted as necessary. The assembly of the piezoelectric vibrator excluding the bonding of is completed.
[0016]
FIG. 8 is a plan view of a solder sheet assembly 50 in which a large number of sheets of encapsulated solder material 5 punched into a frame shape are connected. Each of the frame-shaped solder sheets is positioned at the brazed portion of the lid 3 when the stack is placed on the lower case assembly 20 provided with positioning holes 201 and having the quartz crystal resonator element 1 mounted on the basis of the holes. By making the encapsulated solder material 5 into a sheet having a uniform thickness, the brazing material is not unevenly biased and brazing without defects is achieved.
[0017]
FIG. 9 is a plan view of the lid assembly 30 in which a large number of the lids 3 are connected by performing the drawing process of the lid 3 and the punching leaving the connecting portions. Plating is complete if necessary. The positioning hole 201 is also provided. With this hole as a reference, the lid assembly 30 is further superimposed on the solder sheet assembly 50 superimposed on the lower case assembly 20, and all joints are vacuumed using a jig for clamping the whole. If pressurization and heating are performed uniformly at the same time, the brazing of the lid 3 is completed. Next, by cutting the completed assembly at the cut line 203 shown in FIG. 7, individually completed crystal resonators can be obtained.
[0018]
Next, various modifications in the embodiment of the present invention will be considered. First, in the above-described embodiment, a flat plate vibrating piece such as a double-supported AT plate is used as the crystal resonator. However, this may be a convex plate or a beveled vibrating plate, and may be cantilevered (in this case) Two through-hole positions are arranged on one side of the crystal vibrating piece). A tuning fork-shaped vibrating piece may be used. In addition, the resonator element is not limited to quartz, and may be composed of other piezoelectric crystals or piezoelectric ceramics. A conductive adhesive may be used instead of the high-temperature solder material. Next, as the material of the middle frame, a quartz material is used in order to match the thermal expansion coefficient with glass or a quartz crystal vibrating piece, or an organic material can be considered. The material of the lower case and the metal film can be changed as appropriate. It is obvious that an inorganic material or a resin material whose inner surface is covered with a metal layer can also be used for the lid. When the container material is a substrate material, it is possible to add a necessary wiring pattern and mount and mount other electronic elements as appropriate. It goes without saying that various changes can be made to the configuration or the manufacturing method within the scope of the gist of the present invention.
[0019]
【The invention's effect】
In the present invention, since a resin container having an inner surface covered with a metal layer is used, a piezoelectric vibrator having a thin, small, and lightweight structure at a low cost while maintaining various characteristics such as airtightness. In addition, there is an effect that it is possible to achieve a further cost reduction by making it possible to carry out most of the main processing in the manufacturing method in a state where many parts are assembled.
[Brief description of the drawings]
FIG. 1 is a three-plane view showing the structure of a crystal resonator as an example of an embodiment of the present invention, where (a) is a plan view with a part of a lid cut away, (b) is a central sectional view, and (c) ) Is a bottom view.
FIGS. 2A and 2B are two views of a quartz crystal vibrating piece, wherein FIG. 2A is a plan view and FIG. 2B is a bottom view.
3A and 3B are two views of the middle frame, where FIG. 3A is a plan view and FIG. 3B is a bottom view.
4A and 4B are two views of the lower case, where FIG. 4A is a plan view and FIG. 4B is a bottom view.
FIG. 5 is a plan view of the middle frame alignment jig in use.
FIG. 6 is a plan view of a high-temperature solder sheet assembly.
FIG. 7 is a plan view of the lower case assembly.
FIG. 8 is a plan view of a solder sheet assembly.
9 is a plan view of the lid assembly 30. FIG.
FIG. 10 is a perspective view of a conventional example having a cylindrical container.
FIG. 11 is a perspective view of another conventional example having a box-shaped container.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Crystal resonator element 11 Excitation electrode 12 Crystal extraction electrode 2 Lower case 20 Lower case assembly 201 Positioning hole 202 Long hole 203 Cut line 21 Copper foil part 24 Through hole 25 Lower surface extraction electrode 26 Terminal electrode 27 Case material exposure part 3 Lid 30 Lid assembly 4 High-temperature solder material 40 High-temperature solder sheet assembly 41 Conductive adhesive 5 Encapsulated solder material 50 Solder sheet assembly 7 Middle frame 71 Overhang portion 72 Middle frame through hole 73 Metallized surface 74 Electrode pad 8 Middle frame alignment jig 81 Positioning Pin 82 Middle Frame Pin 91 Airtight Terminal 92 Cap 93 Ceramic Lower Case 94 Lower Case Step 95 Lid 96 Side Electrode

Claims (2)

A lower case made of a substantially flat resin material, the upper surface excluding the immediate vicinity of the predetermined number of through holes being covered with a metal layer, and the lower surface provided with terminal electrodes connected to the lower surface side of the through holes; An inner frame fixed to the upper surface of the lower case, having an inner frame through hole at a position corresponding to the through hole, and having a metallized surface surrounding the inner frame through hole on the lower surface and joined to the metal layer ; A piezoelectric vibrating piece fixed to the upper surface and having excitation electrodes individually connected to the upper surface side of the middle frame through hole by solder or conductive adhesive, and a peripheral portion of the metal layer on the upper surface of the lower case are brazed. the cover the piezoelectric vibrating reed hermetically become more and lid with a metal portion on at least peripheral lower surface inner surface is a metal or an inorganic material, a printed circuit board the lower case which stuck on at least the upper surface of the copper foil And the raw material, the in frame piezoelectric vibrator, wherein forming Rukoto a ceramic material. A step of forming a single middle frame having a middle frame through hole and having a metallized surface surrounding the middle frame through hole on the lower surface, and arranging the middle frame on the surface of the jig plate at a predetermined direction and interval. Covering the upper surface excluding the immediate vicinity of the through holes provided at positions corresponding to the arranged middle frame through holes with a copper foil , and processing a predetermined metal pattern connected to the through holes on the lower surface. Forming a lower case assembly having a shape in which a large number of lower case elements made of printed wiring boards are in close contact with each other and a plurality of lid elements formed at positions corresponding to the arrangement of the lower case elements are mutually connected A step of creating a lid assembly formed by joining, a step of overlapping and joining the lower surface of the middle frame arranged on the jig plate and the upper surface of the lower case assembly, and the upper surface of the individual middle frame Supply piezoelectric vibrating piece And attaching the excitation electrode of the piezoelectric vibrating piece to the through hole, and the lower case assembly on which the piezoelectric vibrating piece is mounted and the lid assembly are aligned and overlapped to form individual lower case elements And a step of forming a large number of piezoelectric vibrators in which the lid elements are joined and connected simultaneously, and a step of cutting and separating the connected piezoelectric vibrators to obtain individual piezoelectric vibrators. A method for manufacturing a piezoelectric vibrator.

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