JP2002359533A - Method of manufacturing piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a piezoelectric oscillator, which can prevent peeling or chipping of an electrode, when uniting a piezoelectric mother board 100 and a capacitor mother board 200 by a binder and cutting them separately for each piezoelectric oscillator. SOLUTION: A manufacturing method is provided, which dices a jointed body, formed by uniting the piezoelectric mother board 100 and the capacitor mother board 200 by a binder and filling wax between them and hardening them and removes the wax 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator in which a piezoelectric substrate and a capacitor substrate are integrated with each other by cutting the bonded substrate of the piezoelectric substrate and the capacitor substrate through a joining member at a time. The present invention relates to a method for manufacturing a piezoelectric vibrator to be obtained.

[0002]

2. Description of the Related Art Hitherto, microcomputers have been widely used for communication equipment and electronic equipment, and these microcomputers have a built-in capacitance type electronic component incorporating a piezoelectric vibrator shown in FIG. 5 as a clock oscillation circuit. A piezoelectric resonator Z is used.

[0003] A clock oscillation circuit is shown in an equivalent circuit diagram for explaining the built-in capacity type piezoelectric resonator Z (FIG. 6). In this clock oscillation circuit, input / output capacitance components C1 and C2 are connected between both ends of the piezoelectric resonator R and the ground E.
The feedback resistance component r between both ends of the piezoelectric resonator R, the inverter I
Is connected. In order to achieve this clock oscillation circuit more easily, a portion surrounded by a dotted line in FIG. 6 is integrated, and a capacitor element C and a piezoelectric resonator R in which the above-mentioned two capacitance components C1 and C2 are formed on one capacitor substrate. A composite electronic component in which a piezoelectric vibrator integrated with the above is incorporated in a case that can be surface-mounted is a built-in capacitance type piezoelectric resonator.

As a specific structure of such a built-in capacitance type piezoelectric resonator Z, a structure shown in a sectional view of FIG. 5 has already been proposed. Since the names and symbols of the constituent members do not essentially change between the conventional example and the present invention, they will be described using the same notation.

In the case 4, a piezoelectric vibrator in which the piezoelectric element 1 and the capacitor element 2 are joined at both ends and integrated is placed. Lower electrodes 23-2 of capacitor element 2
Reference numeral 5 is connected to the lead terminal 5 of the case via a conductive adhesive 7.

A conductive adhesive 7 is applied to the lead terminals 5 of the case 4.
Is applied to the lower electrode 23 of the capacitor element 2.
To 25, connected to the upper electrodes 21 and 22 of the capacitor element 2 via the end face conductor film 16, and connected to the vibrating electrodes 11 and 12 of the piezoelectric element 1. After that, the opening of the case 4 is connected to the metal cover 6 via the sealing resin material 3.
Is attached and hermetically sealed.

The piezoelectric element 1 is formed by forming vibration electrodes 11 and 12 on both main surfaces of a rectangular piezoelectric substrate 10. The capacitor element 2 is formed by providing three lower electrodes 23 to 25 and upper electrodes 21 and 22 on the lower surface of a strip-shaped capacitor substrate 20.
It forms one capacitance component. After bonding both ends of these substrates with a joining member 15, an end face conductor film 16 is formed on both end faces with a conductive adhesive or the like, thereby establishing electrical continuity between the electrodes of the capacitor element 2 and the piezoelectric element 1. Joining member 1
A gap layer is formed between the joining members 15 and 15, and the piezoelectric element generates vibration at a predetermined resonance frequency between the joining members 15 and 15 and can be used as a piezoelectric resonator.

As a method of mass-producing a piezoelectric vibrator in which both ends of the piezoelectric element 1 and the capacitor element 2 are adhered to each other with a joining member, a flat plate-shaped piezoelectric mother board and a capacitor mother board capable of cutting out a large number of each element are available. Prepare a substrate. As shown in FIG. 2, in the piezoelectric mother substrate 100, the piezoelectric element regions 10a of the piezoelectric element 1 in which the opposing vibration electrodes 11 and 12 (not shown) are formed on both sides are arranged in a row and column. . The capacitor mother substrate has the same dimensions as the piezoelectric substrate region 10a,
1 to 25 (not shown) are formed on both sides, and the capacitor substrate regions 20b of the capacitor element 2 are arranged vertically and horizontally.

Then, the joining position is determined from the pattern of the vibrating electrodes formed on the surface of the piezoelectric substrate region 1.
0a and the capacitor substrate region 20b are positioned so as to be vertically aligned, and a bonding member such as a conductive adhesive is applied and bonded in the state of each mother substrate. The dicing tape is attached to a dicing tape 91 with an adhesive attached to the ring 92, and is diced and cut by a cutting groove formed on the piezoelectric mother substrate 100.

[0010]

However, when the piezoelectric vibrator after the dicing cut is closely observed, as shown in FIG. 3, a small chip called chipping A is formed at the cut edge. Here, the cut edge refers to a ridge line portion where the main surface of the piezoelectric element 1 and the cut surface intersect. In particular, after the dicing blade is engaged with the piezoelectric mother substrate 100 or the capacitor mother substrate 200 while rotating, the dicing blade is often generated at a cutting edge on the side where the dicing blade goes out. For example, the piezoelectric element 1 having an oscillation frequency of 16 MHz has a general size of 2.4 mm long × 1.0 mm wide.
It is a strip-shaped element having an X thickness of 0.09 mm, and chipping of several microns to several tens of microns enters the cut edge.

Also, when the electrode formed on the surface of the piezoelectric mother substrate 100 is partially turned up from the substrate near the cutting edge on the side where the dicing blade comes off, B occurs.

Turning electrode B on the surface of the piezoelectric mother substrate 100
Causes variations in the capacitance value of the equivalent circuit of the vibrating body formed on the piezoelectric mother substrate 100, and causes variations in the input / output capacitance value formed on the capacitor element 2, which ultimately results in In addition, the oscillation frequency of the piezoelectric vibrator becomes unstable, causing a problem in reliability that characteristics change during assembly processing or use of the product.

If the magnitude of chipping A is large, the piezoelectric vibrator, which is a bulk vibrator, will generate vibrations having a resonance frequency slightly shifted due to chipping in addition to the original resonance frequency. The waveform has a ripple which is a disturbance of the waveform as indicated by the circle. The piezoelectric oscillator vibrates during the use between the two oscillation frequencies of the original oscillation frequency fa and the ripple oscillation frequency f ′. There is a danger that the oscillating frequency changes to the other oscillation frequency due to a natural stimulus or the like, leading to malfunction of the electronic device. As a method for preventing such electrode turning B and chipping A, it is desirable to reduce the feed speed of dicing and cut at a low speed. It is also desirable to reduce the size of the abrasive grains of the dicing blade. However, lowering the dicing speed lowers productivity, which is a major obstacle in mass production.

The present invention has been devised to solve the above-mentioned problems, and an object of the present invention is to improve the mass productivity without increasing the abrasive grain roughness of a dicing blade to reduce the dicing speed. Another object of the present invention is to provide a method for manufacturing a piezoelectric vibrator capable of obtaining a piezoelectric vibrator having a stable oscillation frequency by preventing electrode turning or chipping at a cutting edge of the piezoelectric vibrator.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a piezoelectric element in which piezoelectric element regions of a piezoelectric element having opposing vibrating electrodes formed on both surfaces are arranged vertically and horizontally. A motherboard, having the same dimensions as the piezoelectric substrate region, having a capacitor motherboard in which capacitor element regions of capacitor elements in which opposing capacitance electrodes are formed on both sides are arranged vertically and horizontally, Cut grooves are formed on either the surface of the piezoelectric mother substrate or the capacitor mother substrate in the direction parallel to the vertical boundary and the direction parallel to the horizontal boundary of the arranged piezoelectric element region or capacitor element region, respectively. The piezoelectric mother substrate and the capacitor mother substrate are brought into contact with each other at least with each of the capacitance electrodes facing each of the vibrating electrodes while making each of the piezoelectric substrate regions and each of the capacitor substrate regions substantially vertically coincide with each other. And a step of filling substantially all of the voids formed between the piezoelectric mother substrate and the capacitor mother substrate with fluid wax, and after solidifying the wax, the piezoelectric Cutting the body mother substrate and the capacitor mother substrate at a time, and dividing each of the piezoelectric element regions and the capacitor element regions individually.

According to the structure of the present invention, since wax is filled between the piezoelectric mother substrate and the capacitor mother substrate, the dicing blade is a laminated body in which the piezoelectric mother substrate, the wax layer and the capacitor mother substrate are integrated. Is cut from the upper side, the force generated when moving from the uppermost substrate to the wax layer, that is,
The frictional resistance and the impact force applied from the dicing blade surface generate a force that pushes the substrate against the wax layer, but this force is received by the wax layer and the impact pressure can be dispersed, enabling high-speed cutting. It is considered that even if a coarse dicing blade is used, chipping of the substrate and turning up of the electrode film can be suppressed, and a change in oscillation frequency can be suppressed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a piezoelectric vibrator according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an external perspective view of a piezoelectric vibrator obtained by the manufacturing method of the present invention. In the figure, the piezoelectric vibrator is integrated by joining members 15 at both ends of a rectangular plate-shaped piezoelectric element 1 and a capacitor element 2.

The piezoelectric element 1 comprises a strip-shaped piezoelectric substrate 10 and vibrating electrodes 11 and 12. Vibrating electrode 11,
Reference numerals 12 are formed so as to face each other near the center of both main surfaces of the piezoelectric substrate 10. The vibration electrode 11 is formed on the upper surface of the piezoelectric substrate 10 and extends to the other end. The vibration electrode 12 is formed on the lower surface of the piezoelectric substrate 10 and extends to one end.

The capacitor element 2 includes a strip-shaped capacitor substrate 20 and a plurality of capacitance electrodes for forming two capacitance components on both upper and lower main surfaces of the capacitor substrate 20. Two upper surface electrodes 21 and 22 are formed on the upper surface of the capacitor substrate 20, and a lower surface electrode for forming a capacitance component on the lower surface of the capacitor substrate 20 and at the same time achieving connection with the outside (three lead terminals 5). 23, 2
4 and 25 are formed.

Further, the upper electrode 2 of the capacitor substrate 20
A part of the first and second electrodes 22 faces the lower electrode 25 of the capacitor substrate 20. That is, when the lower electrode 25 of the capacitor substrate 20 is viewed as a center, a predetermined capacitance component C1 is formed between the capacitor substrate 20 and the upper electrode 21 via the thickness of the capacitor substrate 20, and a predetermined capacitance component C2 is formed between the lower electrode 25 and the upper electrode 22. Is formed.

Incidentally, reference numerals 23, 24 and 25 formed on the lower surface of the capacitor substrate 20 are connection electrodes for connecting to the lead terminals 5 provided on the inner surface of the case shown in FIG.

A method for manufacturing such a piezoelectric vibrator will be described.

In FIG. 2, a piezoelectric mother substrate 100 is
A large-sized substrate made of a piezoelectric ceramic material such as T or PZT, or a single crystal material such as lithium tantalate or lithium niobate, polished to a thickness corresponding to a desired resonance frequency,
Electrode films for forming the vibrating electrodes 11 and 12 are formed on both surfaces thereof by a sputtering method or the like, and an electrode pattern of the vibrating electrodes 11 and 12 from which a large number of piezoelectric vibrators can be cut out is formed by an etching method or the like. The electrode film material is mainly composed of, for example, copper or an Ag-based material. Then, the piezoelectric element regions 10a of the piezoelectric element 1 in which the opposing vibration electrodes 11 and 12 are formed on both surfaces are arranged vertically and horizontally.

Similarly, the capacitor motherboard 200 includes PT,
A large-sized substrate made of a dielectric ceramic material such as BT. In order to form the electrodes 21 to 25, a predetermined electrode pattern is screen-printed on the upper and lower main surfaces of the capacitor mother substrate 200 with a conductive paste mainly containing Ag or the like. It is formed by printing and printing by a method or the like. That is, the capacitor substrate region 2 of the capacitor element 2 having the same dimensions as the piezoelectric substrate region 10a and having the capacitance electrodes 21 to 25 formed on both surfaces.
0b are arranged vertically and horizontally.

The piezoelectric motherboard 100 and the capacitor motherboard 2
00 are integrated by the joining member 15. A piezoelectric substrate 10 and a capacitor substrate 20 are provided at both ends of each piezoelectric vibrator.
The joining member 15 is connected to the piezoelectric mother substrate 10 so that
0 and the capacitor mother board 200 are formed and joined to correspond to the electrode positions of the piezoelectric vibrator. Specifically, a conductive adhesive sheet or a conductive adhesive having a predetermined thickness is placed on the piezoelectric mother substrate in a position-aligned manner, and the capacitor substrates are overlapped with each other and are cured while being pressed.

By selecting the thickness of the joining member 15, the thickness of the entire laminate can be controlled to a predetermined thickness. That is, although the thickness of the piezoelectric element changes according to the resonance frequency of the piezoelectric vibrator, the thickness of the bonding member can be adjusted to make the overall thickness of the multilayer body a predetermined thickness. Thereby, it can be handled under the same conditions, and automatic assembly can be facilitated.

At this time, the joining member 15 does not necessarily need to be a conductive adhesive. However, it is easy to connect the end surface conductor film 16 for drawing out the electrode on the contact surface of the piezoelectric element 1 and the capacitor element 2 to the end surface. It is preferable that the conductive material is electrically conductive because it can be used.

The piezoelectric mother board 100 and the capacitor mother board 2
After the bonded body of No. 00 is heated to about 80 ° C. at which the wax melts, the end surface is dipped in a molten wax bath with the side surface of the bonded body of the substrate facing down. By holding for a while, wax spreads and fills the entire surface between the bonded substrates by surface tension. By cooling after removing the excess wax 8 attached to the dipped end surface, the wax is solidified and integration is achieved.

Next, a metal dicing ring 92 is attached on a dicing tape 91 having an adhesive applied to the upper surface, and a bonded body of the piezoelectric mother substrate 100 and the capacitor mother substrate 200 is attached near the center thereof. At this time, the piezoelectric mother substrate 100 is on the upper surface, and the capacitor mother substrate 200 is on the lower surface. This bonded substrate is cut by a dicing device. The cutting speed is 20 mm / sec, the thickness of the dicing blade is 0.1 mm, and the roughness of the diamond abrasive grains is # 800.

The state of dicing is cut along a cut line indicated by a two-dot chain line in FIG. Cut vertically and horizontally,
Although FIG. 2 schematically shows that 2 × 3 = 6 piezoelectric vibrators are obtained, several tens to several hundreds are cut out in actual cutting from a mother substrate.

Here, the capacitor substrate was attached to the dicing tape 91. This is because the effect of the dicing tape 91 on suppressing the turn-up and chipping of the electrode film is insufficient compared with the effect of the wax of the present invention. The piezoelectric substrate, which is greatly affected by chipping, is located on the upper surface.

After the cutting, the piezoelectric vibrator is separated from the dicing tape 91, washed in a heated organic solvent, and the wax 8 between the piezoelectric substrate and the capacitor substrate is removed.
Is completely eluted.

A conductive adhesive is applied to the end surface of the piezoelectric vibrator and dried, and the vibrating electrodes provided on both main surfaces of the piezoelectric substrate, the capacitance forming electrodes on the upper surface of the capacitor substrate, and the connection electrodes on the lower surface are electrically connected. To form an end face connection electrode. The end face connection electrode may be formed by sputtering instead of the conductive adhesive.

The piezoelectric vibrator thus obtained is subjected to a characteristic test, and then the connection electrode 2 on the lower surface of the capacitor substrate is tested.
3 to 25 are electrically and mechanically connected and fixed to the lead terminals 5 on the inner surface of the resin case 4 with a conductive adhesive,
The metal lid 6 is sealed with an adhesive.

Table 1 shows the result of examining the frequency of occurrence of chipping defects at the cut edges when the dicing conditions were changed. The test was conducted under the same conditions, with or without wax filling the gap between the piezoelectric mother board and capacitor mother board, and with wax filling, changing the abrasive grain roughness of the blade and the blade feed speed. I went about.
The numbers in the table indicate the percentage of the piezoelectric vibrator obtained from one bonded body having chippings of 5 μm or more in the cut ridges in%.

[0036]

[Table 1]

As a result of the experiment, 34-62% chipping was observed in the wax-filled one as in Experiment 2.
It is understood from Experiment 1 that chipping of 5 μm or more can be significantly prevented as compared with 2.3 to 4.2% without wax filling.

In Experimental Examples 2 to 5, it is understood that when the feed rate of the diamond blade is increased, the ratio of chipping of 5 μm or more increases, and as the abrasive flow roughness of the diamond blade increases, the ratio of chipping increases. However, even if the speed is increased and the abrasive grain roughness is increased, the filling of the wax of the present invention can reduce the
It is understood that the chipping can be suppressed to not more than%.

Therefore, for example, the feed rate is set to 20 mm / sec or more due to mass production requirements, and the ratio of the piezoelectric vibrator having a large chipping of 5 μm or more at the cutting edge is 3%.
%, It can be seen that there are many choices for the feed rate and the roughness of the abrasive grains.

However, at a feed rate of 20 mm / sec or more, the speed of cutting the ceramic is considered to be unable to catch up, and the frequency of occurrence of chipping tends to be slightly higher.
At this time, it seems that excessive force is being applied to the blade,
Since the blade could be damaged, the feed rate could not be increased, and in Experiment 5, the blade was damaged and the experiment could not be performed.

[0041]

According to the method of manufacturing a piezoelectric vibrator of the present invention, wax is filled between a piezoelectric mother substrate and a capacitor mother substrate which are integrally joined to each other, so that a blade having a coarse diamond abrasive can be used. Since chipping and turning of the electrode film can be suppressed, a highly reliable piezoelectric vibrator can be provided in which the variation in characteristics due to chipping is suppressed while the dicing speed is increased.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a piezoelectric vibrator of the present invention.

FIG. 2 is an explanatory view before cutting a piezoelectric vibrator of the present invention by dicing.

FIG. 3 is a partial sectional view of a conventional piezoelectric vibrator.

FIG. 4 is an impedance characteristic diagram of a piezoelectric vibrator having chipping.

FIG. 5 is a sectional structural view when the piezoelectric vibrator is used as a surface mount component mounted on a case.

FIG. 6 is an equivalent circuit diagram of a built-in capacitance type piezoelectric resonator which is an example of an electronic component.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric element 10 ... Piezoelectric substrate 100 Piezoelectric mother substrate 11, 12 ... Vibration electrode 15 ... Bonding member 16 ... End surface conductor film 2 ... Capacitor element 20 ... Capacitor substrate 200 ... Capacitor mother substrate 21, 22 ... Top surface electrode 23 24, 25 ... lower surface connection electrode 3 ... sealing member 4 ... case 5 ... lead terminal 6 ... metal lid 7 ... conductive adhesive 8 ... wax 91 ... dicing tape 92 ... dicing ring

Claims (1)

[Claims] 1. A piezoelectric mother substrate in which piezoelectric element regions of a piezoelectric element in which respective opposed vibration electrodes are formed on both sides are arranged vertically and horizontally, and have the same dimensions as the piezoelectric substrate region, A capacitor element region of a capacitor element in which each opposing capacitance electrode is formed on both surfaces has a capacitor mother substrate arranged vertically and horizontally, and the piezoelectric mother substrate and the capacitor mother substrate are each of the piezoelectric substrate regions. And a step of integrally joining each of the capacitor substrate regions while making them substantially coincide with each other in the upper and lower directions, and a step of filling substantially all of the voids formed between the piezoelectric mother substrate and the capacitor mother substrate with fluid wax. After solidifying the wax, cutting the piezoelectric mother substrate and the capacitor mother substrate at a time, and dividing each of the piezoelectric element regions and the capacitor element regions individually. Manufacturing method of the piezoelectric vibrator to.