JP3197009B2 - Manufacturing method of composite longitudinal vibration mechanical filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

The present invention includes a longitudinal vibrator (hereinafter, referred to as a longitudinal vibrating sound piece as necessary), a piezoelectric member, a coupling member, a support member, and the like. The present invention relates to a method for manufacturing a composite longitudinal vibration mechanical filter in which fluctuations in frequency and deterioration in pass band characteristics due to non-uniform length of a sound piece are suitably reduced.

[0002]

[Prior art]

Recently, mechanical filters have been widely used in communication devices and the like as intermediate products in the characteristics of LC filters and crystal filters. Such a mechanical filter has good Q characteristics, selection characteristics, and temperature characteristics, and can be downsized.

One example of this type of composite longitudinal vibration mechanical filter is a fourth example.
Shown in the figure.

In this example, an input-side longitudinal vibration sound piece 2 and an output-side longitudinal vibration sound piece 4 which are arranged on the same surface and are made of a metal material or the like are provided. The input and output side longitudinal vibration sound pieces 2 and 4
The connecting members 6 and 8 having constant elasticity are connected to each other, and the supporting members 10 and 12 are protruded from the center of the outside. I have. Further, a pair of input-side piezoelectric ceramics 14a and 14b are fixed to the input-side longitudinal vibration sound piece 2 by soldering or the like.
The output-side piezoelectric ceramics 16a and 16b are fixed to the piezoelectric element.
Next, the ends of the support members 10 and 12 are
It is fixed to the upper center of a, 24b by laser welding or the like.

Further, between the input side piezoelectric ceramics 14a, 14b and the upright piece 24a, a power supply line 18 to which an input signal is supplied and a ground line 18e.
Are connected to each other, and the output line 20 similarly derives the output signal.
And the ground wire 20e are connected to the output-side piezoelectric ceramics 16a, 16b and the upright piece 24b.

In such a configuration, the input side and output side longitudinal vibrating reeds 2 and 4 connected by the coupling members 6 and 8 are arranged substantially in the air, and do not hinder the operation of the longitudinal vibration and the like. It is formed as follows. Then, the composite longitudinal vibration mechanical filter is housed in a casing (not shown) or the like, and is then used by being mounted on an intermediate frequency amplifier or the like of a communication device or the like.

In the composite longitudinal vibration mechanical filter configured as described above, a high-frequency signal S ₁ passing through a resistor R from a signal source Osc is supplied between a power supply line 18 and a ground line 18 e on an input side piezoelectric ceramic.
It is applied to electrodes (not shown) attached to 14a and 14b. Then, an electric field corresponding to the high-frequency signal is generated between the input-side longitudinal vibration sound piece 2 and the electrically grounded input-side longitudinal vibration sound piece 2. Due to this electric field, the input side piezoelectric ceramics 14a, 14b
Electrostriction occurs in the direction indicated by Vn, and the length of the input-side longitudinal vibration sound piece 2
The longitudinal wave L ₁ resonates at frequencies F ₁ to a half wavelength. Assuming that the average propagation velocity of a longitudinal wave in the input-side longitudinal vibration sound piece 2 is V,
The frequencies F ₁ is given by the following equation.

F ₁ = V / (2L ₁ ) (1) The longitudinal vibration at the frequency F ₁ is mechanically coupled to the output-side longitudinal vibration sound piece 4 by the coupling members 6 and 8, and the output-side longitudinal vibration sound piece is formed. 4 resonates at longitudinal vibration frequency F ₂ by a length L _2. If this frequency F ₂ is set to V average propagation velocity of the longitudinal wave (1) as well as the output side longitudinal vibration vibrating bar _{4, F 2 = V / (} 2L 2) ... a (2). The output-side longitudinal vibration vibrating bar 4 of the longitudinal vibration by the output side piezoelectric ceramic 16a, voltage generated in 16b is derived as a high-frequency signal S ₂ formed in a predetermined steep frequency characteristic and lead-out wire 20 and the ground line 20e You.

[0009]

[Problems to be solved by the invention]

However, in the method of manufacturing the composite vibration mechanical filter according to the above-described conventional technology, the accuracy of the center frequency and the pass band characteristics are regarded as important, and the frequency F _{1 of} each of the input-side and output-side longitudinal vibration sound pieces 2 and 4 is determined. and matching of the center frequency of F ₂ is desired. In this case, the input-side and output-side longitudinal vibrating reeds 2 and 4 are simultaneously manufactured in large quantities by etching or the like, so that it becomes difficult to obtain sufficient dimensional accuracy for each of them, and fluctuations in the center frequency after completion ( (Variation) and deterioration of the pass band characteristics.

[0010] The present invention has been made in view of the above problems,
Through holes and / or non-through holes are formed at the same time by etching processing when manufacturing the vibrating body, etc., and the center frequency during mass production of each vibrating body is formed with high accuracy and fluctuation (variation) is effective It is an object of the present invention to provide a method of manufacturing a composite longitudinal vibration mechanical filter in which pass band characteristics are improved, and mass production is promoted with uniformity.

[0011]

[Means for Solving the Problems]

In order to solve the above problems, in the method of manufacturing a composite longitudinal vibration mechanical filter according to the present invention, a plurality of vibrators including an input side and an output side where a piezoelectric member is superimposed are connected by a coupling member, and the input side and In a method of manufacturing a composite longitudinal vibration mechanical filter in which a support member protruding from an output-side vibrating body is attached to a holding member, when the vibrating body is manufactured by processing using lithography technology, A plurality of through-holes and / or a plurality of non-through-holes having an opening surface smaller than the longitudinal vibration resonance wavelength for preventing center frequency fluctuation are formed at a central portion in a longitudinal direction of each of the vibrators. In this case, the length of the vibrating body is L, the width of the vibrating body is W, and the length of the central portion is
L _M , the width of the through hole and / or the non-through hole is M, and the distribution ratio of the through hole at the center of the length L _M (total area of the through hole / area of the vibrating body center) is γ. the length L _M of the central portion, a substantially L- (W / γ) a first step of pick formed as the input side and a second polymerizing fixing the piezoelectric member which sandwiches the output side of the vibrating body And a step of:

[0012]

[Action]

In the manufacturing method of the composite longitudinal vibration mechanical filter according to the present invention configured as described above, when the input-side and output-side longitudinal vibration bodies are formed as one element by the etching process, a length variation occurs. In this case, the effect of the through hole and / or the non-through hole formed by the etching process at the same time does not cause fluctuation (shift) of the center frequency and deterioration of the pass band characteristic.

[0013]

【Example】

Next, an embodiment of a method for manufacturing a composite longitudinal vibration mechanical filter according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a process diagram of the embodiment, and FIGS. 2 and 3 are perspective views showing the configuration of a composite longitudinal vibration mechanical filter manufactured by the method of manufacturing a composite longitudinal vibration mechanical filter of the present embodiment. .

First, an example shown in FIG. 2 shows an input-side longitudinal vibration sound piece 32 and an output-side longitudinal vibration sound piece having the same shape as the input-side longitudinal vibration sound piece 32.
Has 34. The input side and output side longitudinal vibration sound piece 32
And 34 are arranged on the same plane, and connecting members 36 and 38 formed of thin constant elastic materials are formed. Further, the input side and output side longitudinal vibration sound pieces 32 and 34 are provided with support members 40 and 42 projecting from the center thereof,
As can be easily understood from the figure, through-hole groups 32a and 34a having an opening surface smaller than the resonance wavelength of the longitudinal vibration are formed.

Further, a pair of input-side piezoelectric ceramics 44a, 44b are fixed to the input-side vertical vibration sound piece 32 by soldering or the like. Similarly, output-side piezoelectric ceramics 46a and 46b are also fixed to the output-side longitudinal vibration sound piece 34 by polymerization. Input side piezoelectric ceramics 44a, 44b and output side piezoelectric ceramics 46
Electrodes (not shown) such as metallization are formed in advance on the surfaces of a and 46b. Each end of the support members 40 and 42 is attached to the inner end surface of the rectangular outer frame member 50. In this case, the outer frame member 50 and the input-side and output-side longitudinal vibration sound pieces 32 and 34 are on the same plane.

Hereinafter, the above-described manufacturing method using the photolithography technique will be described in the order of steps.

In the first step (FIG. 1A), the input-side and output-side longitudinal vibrating reeds 32 in which the through-hole groups 32a and 34a having small opening surfaces are formed as compared with the resonance wavelength of longitudinal vibration. And 34, the entirety of the coupling members 36, 38, the support members 40, 42 and the outer frame member 50 on one surface, and a photoresist layer 84 on a flat metal plate 80 designed to obtain desired longitudinal vibration characteristics. Apply.

In the second step (FIG. 1 b), the input side and output side longitudinal vibrating reeds 32 and 34, the coupling members 36 and 38, the support member 4
Light irradiation, for example, ultraviolet light Lx is applied through a mask pattern 86 including the same shape as the outer frame member 50 and the outer frame member 50 to perform exposure processing.

In a third step (FIG. 1c), the photoresist layer 87a, 87b, 87c, 87d, 87e is removed by immersing it in a solvent and developing it. .

In a fourth step (FIG. 1d), portions corresponding to the photoresist layers 87a to 87e of the metal flat plate 80 removed in the third step are removed by performing an etching process.

In this manner, the input side and output side longitudinal vibration sound pieces 32 and 34, the coupling members 36 and 38, the support members 40 and 42, and the outer frame member 50
Are integrally formed.

Then, the input side and the output side longitudinal vibration vibrating pieces 32 and 34 formed in the fourth step are formed on the input side on which a metallized material such as a gold material or a silver material is formed by using a vacuum evaporation method or a sputtering method. And output side piezoelectric ceramics 44a, 44b
And 46a and 46b are polymerized and fixed by soldering.

Thereafter, the input-side piezoelectric ceramics 44a, 44b and the outer frame member
50, a feed line 52 and a ground wire 52e, and output wires 54 and a ground wire to the output side piezoelectric ceramics 46a and 46b and the outer frame member 50.
54e is connected by soldering.

Next, the operation in the above configuration will be described.

First, a high-frequency signal S ₄ from a signal source Osc between a pair of input-side piezoelectric ceramics 44a, 44b and the input-side longitudinal vibration sound piece 32 via a power supply line 52 and a ground line 52e, for example, a superheterodyne type 455kHz generated by frequency conversion unit such as receiver
Are supplied. Thereby rise to electrical field commensurate with the high frequency signal S ₄ between the grounded the input side longitudinal vibration vibrating bar 32 input side piezoelectric ceramic 44a, and 44b. This electric field causes the input-side piezoelectric ceramics 44a, 4a
4b occurs electrostriction in the direction indicated by the arrow mi and mo in Fig., The frequency of the input-side longitudinal vibration vibrating bar 32 is the length L ₄ and the half wavelength of the longitudinal wave
It resonates in F _4. If the average propagation velocity of the longitudinal wave at the input side vertical vibrating the vibrating bar 32 is V, the frequency F ₄ is given by the following equation.

F ₄ = V / (2L ₄ ) (3) This longitudinal vibration is mechanically coupled to the output-side longitudinal vibration sound piece 34 via the coupling members 36 and 38, and propagates. response in the vibration frequency F ₅ by the length which L ₅ piece 34, i.e., resonates with the longitudinal vibration. If this frequency F ₅ is set to V average propagation velocity of the longitudinal wave (3) as well as the output side longitudinal vibration vibrating bar _{34, F 5 = V / (} 2L 5) ... a (4). A predetermined steep frequency characteristic is generated due to the electrostriction of the longitudinal vibration of the output-side longitudinal vibrating piece 34, which generates a voltage at the electrodes (not shown) of the output-side piezoelectric ceramics 46a, 46b due to the transmission of the longitudinal vibration. That is, an intermediate frequency signal of, for example, 455 kHz formed in a narrow-band frequency characteristic is a lead line.
54 is derived as the output signal S ₅ from the ground line 54e.

[0028] The equation (3), as understood from the equation (4), the frequency F ₅ frequency F ₄ and the output-side longitudinal vibration vibrating bar 34 of the input-side longitudinal vibration vibrating bar 32, each length L inversely proportional to the _fourth and L _5. length
Accuracy of L ₄ and L ₅ is determined by a technique such as photolithography as it is manufactured, it is impossible to sufficiently small due to the plate thickness. Generally, the thickness dimensional accuracy δL when the plate thickness is t is as follows: δL = ± 1.5 / 1.0 · t (5) Since the dimensional accuracy δL is formed simultaneously by etching or the like using the input side and output side longitudinal vibration sound pieces 32 and 34 in which the through-hole groups 32a and 34a are formed as one element, the dimensional accuracy δL may fluctuate greatly (variation). , And the signs are the same.

Here, the through-hole groups 32a and 34a will be described.

Length L of input side and output side longitudinal vibration sound pieces 32 and 34
(L ₄ , L ₅ ), the width of the through-hole is M, and the distribution ratio of the through-hole groups 32a, 34a on the input-side and output-side longitudinal vibrating reeds 32 and 34 (total area of through-holes / central portion of the longitudinal vibrating reed Γ,
The width of the input-side and output-side longitudinal vibration sound pieces 32 and 34 is W, the length of the portion where the through-hole groups 32a and 34a are present (the longitudinal vibration direction) is L _M ,
The average mass of the material constituting the input-side and output-side longitudinal vibration sound pieces 32 and 34 is defined as ρ.

The plurality of through-hole groups 32 a and 34 a provided in the input-side and output-side longitudinal vibration sound pieces 32 and 34 are sufficiently smaller than the resonance wavelength of the longitudinal vibration, so that the input-side and output-side longitudinal vibration sound pieces 32 are provided. And 34 do not interfere with the vibration operation. Through-hole group 32a to rise to longitudinal vibration, average cross-sectional area S ₁ of the portion of 34a is reduced because the through-hole group 32a, 34a, the _{S 1 = (W-γM)} · t ... (6). The vertical vibration sectional area S ₂ of the portion without the through hole group 32a, a 34a is _{S 2 = W · t ... (} 7).

Considering the dimensional accuracy δL, when the width W is reduced by the dimensional accuracy δL (over-etching) due to the influence of the etching process or the like, the through holes (32a, 34a) are expanded by the dimensional accuracy δL, S ₁ = {(W−δL) −γ (M + δL)} · t = {W−γM− (1 + γ) δL} · t (8) S ₂ = (W−δL) · t (9) .

The length L (L ₄ , L ₅ ) of the input-side and output-side longitudinal vibration sound pieces 32 and 34 is (L−δL).

[0034] Considering the mass addition effect of the input side and output side longitudinal vibration vibrating bar 32 and 34, when the [delta] L = 0, substantially at the center of the length L _M of the through-hole group 32a or 34a is formed except manner sectional area {(W-γM) · t } each tip of the input side and output side longitudinal vibration vibrating bar 32 and 34 having a (through-hole group 32a, a central portion of the length L _M of 34a is formed and at the four corners) of the end portion, respectively, the width GanmaM / 2 obtained by dividing the length obtained by subtracting the width (W-γM) from the width W 2, the length (L-L _M) / 2
Multiplied by the average mass ρ to a rectangular parallelepiped consisting of
2) There is a mass addition for • {(L−L _M ) / 2} · t · ρ. After all, the mass of the quadruple mass {γM · (L−L _M ) · t · ρ} (A) is added to the tip of each of the output side longitudinal vibration sound sides 32 and 34. The length of the side longitudinal vibration sound pieces 32 and 34 is L.

When δL ≠ 0, if overetching occurs, the cross-sectional area at the center is the cross-sectional area {(W−γM) · t} when δ = 0.
In addition, the total width W is W−δL, and the width M of the through hole is M +
δL, the sectional area ｛(W−γM
− (1 + γ) δL) · t}. Then, this cross-sectional area ｛(W−γM− (1 + γ) δL)
At the tip (the four corners of the above-mentioned ends) of the longitudinally vibrating reeds 32 and 34 on the input and output sides of t ｛, the mass ΔγM
· (L-L _M) · formula the entire length L of t · [rho} is substituted into the -δL and width M becomes M + .DELTA.M, the result of the expression of substituting γ
(M + δL) · (L−δL−L _M ) · t · δ, (L−
L _M ) ≫ δL, the positive mass ｛(γM
+ ΓδL) · (L−L _M ) · t · ρ｝. Further, the length W (L ₄ , L ₅ ) and the width W × length δ are added to the both ends of the length L (L ₄ , L ₅ ) of the input-side and output-side longitudinal vibration sound pieces 32 and 34.
L / 2 x thickness t x average mass ρ x 2 mass ｛(-δL) · W
・ Add mass of t ・ ρ｝ (Mass loss because it is minus)
There is. Therefore, when δL ≠, the mass represented by the following formula (A), which is obtained by combining the mass addition of the positive mass and the mass loss, is added. γ (M + δL) · (L−L _M ) · t · ρ + (− δL) · W · t · ρ (a) By the way, in the case of a longitudinal vibrating reed, when mass is added to both ends, the center is The frequency (resonance frequency) decreases,
If the addition of mass in the equations (A) and (A) has the same value between δL = 0 and δL ≠ 0, the resonance frequency does not change even if overetching occurs. Therefore, let us consider the mass addition δρ due to δL ≠ 0, which is obtained by subtracting the expression (A) from the expression (A). δρ is expressed as δρ = {γ (M + δL) · (L−L _M ) · t · ρ + (− δ L) · W · t · ρ ・ − ｛γM · (L−L _M ) · t · ρ｝ = γδL (L−L _M ) · t · ρ−δL · W · t · ρ = δL ｛γ (L−L _M ) −W｝ · t · ρ (C) In the equation (c), the value {γ (L−L _M ) −W} = 0, that is, the length L _M of the central portion where the through-hole group 32a is formed is denoted by L _M
= L− (W / γ) (D), the mass change δρ becomes δρ = 0 even when δL ≠ 0. Thus, by selecting L _M = L− (W / γ), the resonance frequency of the longitudinal vibration sound piece 32 does not change even if over-etching occurs.

Comparing the above equation with the above equation, the newly added mass addition δρ when δL ≠ 0 is given by the following equation.

Δρ = δL · ｛γ (L−L _M ) −W｝ · t · ρ · ｛(W−γM) · t · ρ｝ / ｛(W−γM− (1 + γ) δL) · t · ρ … (10) Here, γ (L−L _M ) −W = 0 That is, by selecting L _M as L _M = L−W / γ (11), δρ ≠ = 0, there is no change in the mass addition, and therefore, the resonance frequencies of the input and output longitudinal vibrating reeds 32 and 34 do not change.

As can be understood from the above description, the through-hole groups 32 a and 34 a having opening surfaces sufficiently smaller than the longitudinal vibration resonance wavelength are formed in the input-side and output-side longitudinal vibration sound pieces 32 and 34. Therefore, sufficient dimensional accuracy cannot be obtained due to the etching process or the like when the input side and output side longitudinal vibration sound pieces 32 and 34 are manufactured as one element, that is, length variations occur. Even in this case, the effect of the through-hole groups 32a and 34a simultaneously formed by the etching process or the like does not cause a change (variation) in the center frequency of the manufacturing method of the composite longitudinal vibration mechanical filter, that is, deterioration of the pass band characteristics. .

Next, FIG. 3 shows another example in which five longitudinal vibrating reeds are used and the attenuation outside the pass band is improved.

In this example, the input-side and output-side longitudinal vibration sound pieces 70 and 78
A plurality of longitudinal vibration sound pieces 72, 74, 76 are provided between them, and further, in the coupling members 82a, 82b and 84a, 84b and 86a, 86b and 88a, 88b, the respective longitudinal vibration sound pieces 70 to 78 are connected. I have.

The portions indicated by reference numerals 70a, 72a, 74a, 76a and 78a are through-hole groups formed in the longitudinal vibrating pieces 70, 72, 74, 76 and 78, respectively.

Support members 90 and 92 are provided protruding from the central portions of the input-side and output-side longitudinal vibration sound pieces 70 and 78, and their ends are fixed to the outer frame member 110.

Further, a pair of input-side piezoelectric ceramics 99a, 99b and output-side piezoelectric ceramics 101a, 101b are fixed to the input-side and output longitudinal vibration sound pieces 70 and 78 by polymerization. Reference numerals 122, 122e and 124, 124e are a feeder line, a ground line, a lead line, and a ground line, respectively.

The manufacturing method and the operation by the photolithography technique in such a configuration are basically the same as those of the above-described embodiment, and the duplicated description will be omitted.

As described above, when the multistage longitudinal vibration vibrating pieces 70 to 78 are provided, variations among the longitudinal vibrating vibrating pieces 70 to 78 are reduced, and in particular, the pass band characteristics are improved. The effect is great.

In each of the above examples, the through-hole groups 32a and 34a
70a to 78a show the case where each of the longitudinal vibration sound pieces 32 and 34 and 70 to 78 penetrate the member, but the present invention is not limited to this. Forming through-holes and / or non-through-holes (dents);
Further, the present invention includes the formation of any one or two or more of the longitudinal vibration sound pieces 32 and 34 and 70 to 78.

[0047]

【The invention's effect】

As described above, according to the method for manufacturing a composite longitudinal vibration mechanical filter of the present invention, at least one or more of the plurality of vibrating bodies including the input side and the output side have at least one through hole and / or non-through hole. It is characterized by being formed in.

As a result, the center frequency is determined with high accuracy, the pass band characteristics are improved, and the characteristics of each of the longitudinally vibrating reeds are reduced. This has the effect of improving quality.

[Brief description of the drawings]

FIG. 1 is a perspective view showing steps of a method for manufacturing a composite longitudinal vibration mechanical filter according to the present invention.

FIGS. 2 (a) and 2 (b) are perspective views showing the configuration of a composite longitudinal vibration mechanical filter manufactured by the method of manufacturing the composite longitudinal vibration mechanical filter shown in FIG.

FIG. 3 is a perspective view showing another configuration example of the composite longitudinal vibration mechanical filter manufactured by the method of manufacturing the composite longitudinal vibration mechanical filter shown in FIG.

FIG. 4 is a perspective view showing a configuration example according to a conventional method of manufacturing a composite longitudinal vibration mechanical filter.

[Explanation of symbols]

 32: Input side longitudinal vibration sound piece, 34: Output side longitudinal vibration sound piece 32a, 34a: Through hole group, 36, 38 ... Coupling member 40, 42 ... Support member 44a, 44b ... Input side piezoelectric Ceramics 46a, 46b: Output side piezoelectric ceramics 50: Outer frame member, 80: Metal plate 84: Photoresist layer, 86: Mask pattern

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-121512 (JP, A) JP-A-61-6915 (JP, A) JP-A-59-161113 (JP, A) JP-A-61-61113 139115 (JP, A) JP-A-52-87340 (JP, A) JP-A-60-82837 (JP, U) JP-B-44-24961 (JP, B1) ⁷ , DB name) H03H 9/46-9/52

Claims (1)

(57) [Claims] A plurality of vibrating bodies including an input side and an output side on which piezoelectric members are superimposed are connected by a coupling member, and a supporting member projecting from the input side and the output side vibrating bodies is attached to a holding member. In the method of manufacturing a composite longitudinal vibration mechanical filter, when the vibrating body is manufactured by a processing process using lithography technology, the processing process simultaneously causes a longitudinal vibration resonance wavelength at a central portion in a longitudinal direction of each of the vibrating bodies. When forming a plurality of through holes and / or a plurality of non-through holes for preventing center frequency fluctuation having an opening surface smaller than that of W, the length of the central part
L _M , the width of the through hole and / or the non-through hole is M, and the distribution ratio of the through hole at the center of the length L _M (total area of the through hole / area of the vibrating body center) is γ. the length L _M of the central portion, a substantially L- (W / γ) a first step of pick formed as the input side and a second polymerizing fixing the piezoelectric member which sandwiches the output side of the vibrating body A method for manufacturing a composite longitudinal vibration mechanical filter, comprising the steps of: