Piezoelectric vibration device and method for manufacturing the same

Abstract

To provide a piezoelectric vibration device and a method for manufacturing the same that improve the visibility of the laser-engraved portion of a molded portion whose main component is filler particles.SOLUTION: A piezoelectric vibration device 1 includes a substrate 11, a vibrator 2 mounted on the substrate 11, an integrated circuit element 10 mounted on the substrate 11, and a molded portion 12 made of a mixture of at least a plurality of spherical filler particles 12a and a thermosetting resin 12b, and covering at least the vibrator 2. The molded portion 12 has a plurality of filler particles 12a, including filler particles 12a of different particle sizes, bonded together by the thermosetting resin 12b, and has a groove portion 13 formed on its surface by irradiation with a laser L. The groove portion 13 has a groove width W that is at least 0.9 times the particle size of the largest filler particle 12a among the filler particles 12a contained in the molded portion 12.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a piezoelectric vibration device and a method for manufacturing a piezoelectric vibration device. [Background technology]

[0002] In order to meet the demand for miniaturization of various electronic devices, piezoelectric resonator devices having a piezoelectric element and an integrated circuit element mounted on a substrate are required. Therefore, a piezoelectric resonator device is known in which the piezoelectric resonator and the integrated circuit element are mounted in a stacked structure on the substrate. The piezoelectric resonator device includes a substrate having external connection terminals on its underside and wiring electrodes on its upper side electrically connected to the external connection terminals, a piezoelectric resonator and the integrated circuit element disposed on the upper side of the substrate and electrically connected to the wiring electrodes, and a molded part covering the piezoelectric resonator.

[0003] In order to identify the type of such miniaturized piezoelectric vibration device, a technique is known in which letters or the like are engraved on the molded portion using a laser. Patent Document 1 describes processing a solder resist covering a substrate with convex portions for displaying letters or the like by heating with a laser. The solder resist is made of an insulating resin that can be easily deformed and discolored by heat. Therefore, when irradiated with a laser, the solder resist foams due to the heat of the laser, and the surface swells and discolors. The swelled and discolored portions of the surface are recognized as letters or the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-123682 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, the molded portion covering the piezoelectric vibrator not only insulates the piezoelectric vibrator but also protects it from impacts and the like. The molded portion, which requires strength, is composed of filler particles, which are granular silica glass, and an insulating resin. The filler particles are bonded by the insulating resin. In other words, the molded portion is composed primarily of the filler particles. The filler particles have high heat resistance and do not deform or discolor due to the heat of the laser. Therefore, the molded portion sometimes has low visibility of the portions engraved by laser processing.

[0006] The present invention aims to provide a piezoelectric vibration device and a method for manufacturing a piezoelectric vibration device that improves the visibility of a portion engraved by a laser on a molded part whose main component is filler particles. [Means for solving the problem]

[0007] The present inventors have investigated piezoelectric vibration devices that improve the visibility of the laser-engraved portion of a molded part that mainly contains filler particles. As a result of extensive investigation, the present inventors have come up with the following configuration.

[0008] The piezoelectric vibrator device includes a substrate, a piezoelectric vibrator mounted on the substrate, an electronic component mounted on the substrate, and a molded portion that is made of a mixture of a plurality of spherical filler particles and an insulating resin and covers at least the piezoelectric vibrator. The molded portion has a plurality of filler particles with different particle sizes bonded together by the insulating resin, and has a groove formed on its surface by laser irradiation. The groove has a width that is at least 0.9 times the particle size of the largest filler particle contained in the molded portion.

[0009] In the piezoelectric vibration device described above, a groove is formed in the molded portion by irradiating the molded portion with a laser. The insulating resin in the molded portion, located in the portion irradiated with the laser, is sublimated within a range of a groove width of at least 0.9 times the particle size of the largest filler particle contained in the molded portion and a predetermined groove depth. The filler particles contained entirely within the groove are separated from adjacent filler particles by the sublimation of the insulating resin and are released from the groove. This results in a recessed portion in the groove that is recessed below the surface of the molded portion.

[0010] For filler particles that are not partially contained within the groove, at least a portion of the bond between adjacent filler particles and the insulating resin remains without sublimation. Therefore, the filler particles remain within the groove. In this case, if the groove has a width 0.9 times the diameter of the largest filler particle contained in the molded part, the filler particle is located in the center of the groove, and the top of the filler particle is located on the same plane as the surface of the molded part, the depth from the surface of the molded part to the surface of the filler particle at the wall of the groove is approximately 0.6 times the radius of the filler particle.

[0011] On the other hand, if the groove width is 0.8 times the particle size of the largest filler particle among the filler particles, the depth from the surface of the molded part to the surface of the filler particle at the groove wall position is approximately 0.4 times the radius of the filler particle. Therefore, by making the groove width 0.9 times or more the particle size of the largest filler particle among the filler particles, the groove depth can be greater than half the radius of the filler particle. As a result, the groove becomes more visible because there is a large difference between the light reflection on the surface of the molded part and the light reflection at the upper end portion of the groove wall created by laser irradiation. This improves the visibility of the laser-engraved portion of the molded part, which is primarily composed of filler particles.

[0012] From another viewpoint, the piezoelectric vibration device of the present invention preferably includes the following configuration: The groove portion has a groove depth equal to or less than the groove width.

[0013] In the above-described configuration, the condition of the bottom surface of the groove machined by the laser differs from the condition of the surface of the molded part. Therefore, the surface of the molded part and the bottom surface of the groove are easily recognized as different parts due to differences in light reflection. When the groove depth of the groove is equal to or less than the groove width, the bottom surface of the groove is visible within a range of 45 degrees or more in the groove width direction, based on a perpendicular line to the bottom surface located at the center of the groove width. In other words, the groove is configured so that the bottom surface is visible within a range wider than the range where a recognizer's viewpoint is likely to be located when recognizing the groove as a character. On the other hand, the range in which the bottom surface of the groove is visible becomes narrower than the range where a recognizer's viewpoint is likely to be located as the groove depth increases compared to the groove width. Therefore, if the depth is equal to or less than the groove width, the recognizer can easily recognize the bottom surface, thereby further improving the visibility of the portion engraved by the laser on the molded part primarily composed of filler particles.

[0014] From another viewpoint, the piezoelectric vibration device of the present invention preferably includes the following configuration: The groove portion has a groove depth that is 0.5 times or less the particle size of the largest filler particle among the filler particles contained in the molded portion.

[0015] In the above configuration, when the groove has a groove depth of 0.5 times or less the particle size of the largest filler particle contained in the molded part, the filler particle is located in the center of the groove, and the top of the filler particle is located on the same plane as the surface of the molded part, the bottom of the groove is located on the outer edge of the filler particle when viewed perpendicular to the bottom. In other words, the bottom is not located inside the outer edge of the filler particle when viewed perpendicular to the bottom. Therefore, when viewed perpendicular to the bottom, the bottom is not covered by or shaded by the filler particles, and is easily visible as a part distinct from the surface of the molded part. This improves the visibility of the part engraved by laser on the molded part, which is primarily composed of filler particles.

[0016] According to another aspect, the method for manufacturing a piezoelectric vibration device of the present invention preferably includes the following configuration: a method for manufacturing a piezoelectric vibration device having a substrate, a piezoelectric vibrator mounted on the substrate, an electronic component mounted on the substrate, and a molded portion covering at least the piezoelectric vibrator, wherein a groove is formed in the molded portion by irradiating it with a laser. The method for manufacturing a piezoelectric vibration device includes a molding step of forming the molded portion by covering at least the piezoelectric vibrator with a mixture of insulating resin and a plurality of filler particles having different particle sizes; and a groove forming step of focusing a laser on the laser light source side of the surface of the molded portion to form a groove having a groove width of at least 0.9 times the particle size of the largest filler particle contained in the molded portion. In the groove forming step, the irradiation diameter of the laser irradiated on the surface of the molded portion is at least 0.5 times but less than 1 time the groove width.

[0017] In the above-described method for manufacturing a piezoelectric vibration device, the groove forming step forms a groove having a groove width 0.9 times the particle diameter of the largest filler particle contained in the molded section. When the filler particle is located at the center of the groove and the top of the filler particle is located flush with the surface of the molded section, the depth from the surface of the molded section to the surface of the filler particle at the wall of the groove is approximately 0.6 times the radius of the filler particle. Therefore, by setting the groove width to at least 0.9 times the particle diameter of the largest filler particle, the groove can have a groove depth greater than half the radius of the filler particle. As a result, the difference between the light reflection on the surface of the molded section and the light reflection on the surface of the filler particle near the wall of the groove is large.

[0018] The grooves are formed in stages by multiple times irradiating the surface of the molded part with a laser beam that is defocused to widen the laser irradiation diameter on the surface of the molded part and reduce the energy per unit area. This reduces the irregularities on the bottom surface of the grooves, allowing them to be formed with high precision. This improves the visibility of the laser-engraved portion of the molded part, which is primarily composed of filler particles.

[0019] From another viewpoint, the method for manufacturing a piezoelectric vibration device of the present invention preferably includes the following configuration: In the groove forming step, the laser is irradiated onto the surface of the molded part so that a part of the irradiation diameter overlaps when viewed in a direction perpendicular to the surface of the molded part.

[0020] In the above-described configuration, the laser is irradiated onto the surface of the molded part so that a portion of the laser irradiation diameter overlaps. Therefore, the insulating resin inside the groove is irradiated with the laser without exception. Furthermore, because the laser is defocused, the amount of energy per unit area within the irradiation diameter is reduced. Therefore, the difference between the amount of depression in the area irradiated once with the laser and the amount of depression in the area irradiated twice with the laser on the bottom surface is suppressed. This improves the light reflectivity of the bottom surface of the groove, making it easier to visually recognize the surface of the molded part and the bottom surface of the groove as different parts. This improves the visibility of the portion engraved by the laser on the molded part, which is primarily composed of filler particles. [Effects of the Invention]

[0021] According to one embodiment of the present invention, it is possible to improve the visibility of the portion engraved by a laser on the molded part mainly composed of filler particles. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a plan view of a piezoelectric vibration device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view of a vibrator in the piezoelectric vibrating device according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along the line IV in FIG. 1 showing the piezoelectric vibration device according to the first embodiment of the present invention in a molded state. [Figure 5] FIG. 5 is a plan view showing the second mounting surface of the substrate in the piezoelectric vibration device according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view perpendicular to the extension direction of a groove formed in a molded part of the piezoelectric vibration device according to the first embodiment of the present invention. [Figure 7]FIG. 7 is a cross-sectional view perpendicular to the stretching direction in which the filler particle with the largest particle size is located in the center of a groove formed in a molded part in the piezoelectric vibration device according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view perpendicular to the stretching direction in which filler particles with the maximum particle size are positioned on the side surface of a groove formed in a molded portion of the piezoelectric vibration device according to the first embodiment of the present invention. [Figure 9] FIG. 9 is a schematic cross-sectional view showing a molding step in the method for manufacturing the piezoelectric vibration device according to the first embodiment of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view showing a laser irradiation state in the groove forming step of the method for manufacturing the piezoelectric vibration device according to the first embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view showing an overlapping laser irradiation range in the groove forming step of the method for manufacturing the piezoelectric vibration device according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Each embodiment will be described below with reference to the drawings. In each drawing, the same parts are denoted by the same reference numerals, and the description of the same parts will not be repeated. Note that the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components and the dimensional ratios of each component. Note that in the following embodiments, the term "main surface" refers to the surface with the largest area in the target component, or the surface with the largest area visible when viewed in the thickness direction in the case of a plate-like component.

[0024] In the following description of the piezoelectric vibration device 1 according to an embodiment of the present invention, the longitudinal direction of the vibrator 2 and the substrate 11 is referred to as the "X direction," the lateral direction as the "Y direction," and the direction perpendicular to the X and Y directions as the "Z direction." In this embodiment, the X and Y directions are directions on a horizontal plane. The Z direction is the vertical direction. However, these definitions of directions are not intended to limit the orientation of the piezoelectric vibration device 1 during use.

[0025] Furthermore, in the following description, expressions such as "fix," "connect," "join," and "attach" (hereinafter referred to as "fixing") include not only cases where members are directly fixed to each other, but also cases where members are fixed via other members. In other words, in the following description, expressions such as "fixing" include both direct and indirect fixing of members to each other.

[0026] [Embodiment 1] <Configuration of Piezoelectric Vibration Device 1> Next, a piezoelectric vibration device 1 according to a first embodiment of the present invention will be described with reference to Figs. 1 to 6. Fig. 1 is a plan view of the piezoelectric vibration device 1 according to the first embodiment of the present invention. Fig. 2 is a side view of a vibrator 2 in the piezoelectric vibration device 1. Fig. 3 is a cross-sectional view taken along the line III in Fig. 2. Fig. 4 is a cross-sectional view taken along the line IV in Fig. 1, showing the piezoelectric vibration device 1 in a molded state. Fig. 5 is a plan view showing a second mounting surface 11b of a substrate in the piezoelectric vibration device 1. Fig. 6 is a cross-sectional view perpendicular to the extension direction of a groove portion 13 formed in a molded portion 12 in the piezoelectric vibration device 1.

[0027] As shown in FIG. 1, the piezoelectric vibration device 1 includes a vibrator 2, an integrated circuit element 10, a substrate 11, and a molded part 12 (see FIG. 4).

[0028] 2 to 4, the vibrator 2 is a piezoelectric vibrator having a piezoelectric body that converts an applied force into a voltage or converts an applied voltage into a force. The vibrator 2 is a piezoelectric vibrator having a piezoelectric diaphragm 3, a first sealing member 6, and a second sealing member 7. The vibrator 2 has a sandwich structure in which the piezoelectric diaphragm 3 is sandwiched between the first sealing member 6 and the second sealing member 7.

[0029] As shown in FIG. 2, the first sealing member 6 and the second sealing member 7 are members that seal the vibrating portion 4 of the piezoelectric diaphragm 3. The first sealing member 6 and the second sealing member 7 are rectangular plate-shaped members made of the same quartz crystal as the piezoelectric diaphragm 3. The first sealing member 6 and the second sealing member 7 are shaped so that when their main surfaces face the main surface of the piezoelectric diaphragm 3, they can cover the entire main surface of the piezoelectric diaphragm 3. The first sealing member 6 and the second sealing member 7 have a bonding material 5 on one main surface that bonds to the bonding material 5 of the piezoelectric diaphragm 3.

[0030] As shown in FIG. 3, the piezoelectric diaphragm 3 is a rectangular plate-shaped member made of quartz crystal, a piezoelectric material. One and the other main surfaces of the piezoelectric diaphragm 3 have a pair of excitation electrodes 4a. The piezoelectric diaphragm 3 also has a cutout portion 4b that penetrates from one main surface to the other so as to surround the pair of excitation electrodes 4a, leaving a portion uncovered. As a result, the portion where the pair of excitation electrodes 4a is located is configured as a cantilevered vibration part 4 that can vibrate in the Z direction. The piezoelectric diaphragm 3 has a bonding material 5 on both main surfaces that is bonded to a first sealing member 6 and a second sealing member 7 so as to surround the vibration part 4.

[0031] One main surface of the piezoelectric diaphragm 3 is covered with a first sealing member 6. The other main surface of the piezoelectric diaphragm 3 is covered with a second sealing member 7. At this time, the bonding material 5 of the piezoelectric diaphragm 3 and the bonding materials 5 of the first sealing member 6 and the second sealing member 7 are diffusion bonded. As a result, the vibrating portion 4 of the piezoelectric diaphragm 3 is hermetically sealed by the first sealing member 6 and the second sealing member 7.

[0032] 1, the first sealing member 6 has four vibrator mounting terminals 6a on the other main surface thereof, which are electrically connected to the electrodes of the substrate 11. The four vibrator mounting terminals 6a are plate-shaped terminals made of conductive metal. The four vibrator mounting terminals 6a are located at the four corners of the first sealing member 6, respectively.

[0033] The vibrator 2 configured in this manner is configured as a three-layer package in which both main surfaces of the piezoelectric diaphragm 3 are sealed with a first sealing member 6 and a second sealing member 7, respectively. Furthermore, by covering both main surfaces of the piezoelectric diaphragm 3 with the first sealing member 6 and the second sealing member 7, an internal space is formed in the vibrator 2 that contains the vibration unit 4 of the piezoelectric diaphragm 3. In other words, the vibrator 2 has the vibration unit 4, including a pair of excitation electrodes 4a, hermetically sealed in the internal space of this package. The internal space is maintained in a vacuum state. The vibrator 2 oscillates at a predetermined frequency in response to an applied voltage. Note that the vibrator 2 may be configured such that an inert gas, such as nitrogen gas, is sealed in the internal space.

[0034] As shown in Figure 1, the integrated circuit element 10 is an electronic component that, together with the resonator 2, constitutes an oscillator circuit. The integrated circuit element 10 has electronic circuits such as an oscillation circuit that is connected to a temperature-sensitive element (thermistor) that detects the ambient temperature and generates a predetermined oscillation output. The integrated circuit element 10 outputs the oscillation output generated by the oscillation circuit as a reference signal such as a clock signal to the outside via the integrated circuit element mounting terminals 10a. The integrated circuit element 10 is covered with resin except for the integrated circuit element mounting terminals 10a.

[0035] The substrate 11 is a resin substrate that electrically connects and integrates the vibrator 2 and the integrated circuit element 10 via a wiring pattern. The substrate 11 is made of, for example, any one of glass epoxy resin, polyimide resin, and fluororesin. A wiring pattern including pads, lands, etc. is located on one of a pair of main surfaces of the substrate 11. The wiring pattern is formed of a conductor such as copper. In this way, one main surface of the substrate 11 is configured as a first mounting surface 11a that has the wiring pattern.

[0036] A vibrator 2 and an integrated circuit element 10 are mounted on a first mounting surface 11a of the substrate 11. The vibrator 2 is disposed on the substrate 11 with a second sealing member 7 (see FIG. 2) facing the first mounting surface 11a. Four vibrator mounting terminals 6a (see FIG. 4) of the first sealing member 6 are electrically connected to the wiring pattern on the first mounting surface 11a by wires 10b and via wire connection terminals 11p on the first mounting surface 11a.

[0037] Similarly, the integrated circuit element mounting terminals 10a of the integrated circuit element 10 are electrically connected to the wiring pattern on the first mounting surface 11a via the wires 10b and the wire connection terminals 11p, which are wire connection pads on the first mounting surface 11a. In this way, the vibrator 2 and the integrated circuit element 10 are positioned side by side on the first mounting surface 11a of the substrate 11.

[0038] 5, the other main surface of the substrate 11, which is parallel to the one main surface, is configured as a second mounting surface 11b having external connection terminals 11g for mounting on an external substrate (not shown). The external connection terminals 11g are plate-shaped terminals made of conductive metal. The external connection terminals 11g are electrically connected to the wiring pattern including multiple pads on the first mounting surface 11a via internal wiring (not shown).

[0039] The second mounting surface 11b of the substrate 11 is the other main surface electrically connected to an external substrate (not shown). The second mounting surface 11b has four external connection terminals 11g at its four corners. The second mounting surface 11b also has four recesses 11j corresponding to the four external connection terminals 11g. The four recesses 11j are stepped portions recessed in a direction perpendicular to the second mounting surface 11b within arbitrarily determined ranges. The recesses 11j are shaped so that mounting terminals of an external substrate can be placed inside each recess.

[0040] One main surface of the external connection terminal 11g is configured as a terminal to be bonded to a connection terminal of an external substrate (not shown). The four external connection terminals 11g (hereinafter simply referred to as "external connection terminals 11g") are substantially rectangular plate-like terminals made of conductive metal. The external connection terminals 11g are respectively located in the four recesses 11j. The external connection terminals 11g have a bonding surface 11h that is bonded to a connection terminal of the external substrate. The bonding surface 11h is located closer to the first mounting surface 11a than the second mounting surface 11b. The external connection terminals 11g are bonded to the connection terminals of the external substrate (not shown) by solder or the like.

[0041] The substrate 11 is configured so that the resonator 2 and the integrated circuit element 10 mounted on the first mounting surface 11a can be electrically connected to an external substrate (not shown) via a wiring pattern (not shown) on the first mounting surface 11a and external connection terminals 11g on the second mounting surface 11b, causing the resonator 2 to oscillate at a predetermined frequency when a voltage is applied from the external substrate.

[0042] 4, the molded part 12 protects at least the resonator 2 of the substrate 11 and the resonator 2 and integrated circuit element 10 mounted on the substrate 11. The molded part 12 covers at least a part of the resonator 2 of the substrate 11 and the resonator 2 and integrated circuit element 10 mounted on the substrate 11. In this embodiment, the molded part 12 covers the first mounting surface 11a of the substrate 11, and the resonator 2, integrated circuit element 10, and wires 10b mounted on the first mounting surface 11a of the substrate 11.

[0043] The second mounting surface 11b of the substrate 11 is not molded by the molded portion 12. The molded portion 12 is configured to cover the portion of the piezoelectric vibration device 1 that is located farthest from the first mounting surface 11a in a direction perpendicular to the first mounting surface 11a, with a thickness of at least approximately 350 μm. In this embodiment, the molded portion 12 is configured so that the thickness from the surface 12c of the molded portion 12 parallel to the first mounting surface 11a to the wire 10b that is farthest from the first mounting surface 11a is approximately 100 μm. The molded portion 12 has grooves 13 (see FIG. 6) for displaying characters, figures, etc.

[0044] As shown in FIG. 6, the molded portion 12 is a mixture containing a plurality of filler particles 12a (hatched portion) made of approximately spherical silica glass and a thermosetting resin 12b (lightly shaded portion) such as epoxy resin. The thermosetting resin 12b is an insulating resin. The molded portion 12 is composed primarily of the plurality of filler particles 12a. In this embodiment, the molded portion 12 is composed of a mixture of filler particles 12a occupying approximately 90% of the molded portion 12, thermosetting resin 12b occupying approximately 10% of the molded portion 12, and other minor components. The plurality of filler particles 12a are bonded to each other by the thermosetting resin 12b. In this case, the thermosetting resin 12b fixes the relative positions of adjacent filler particles 12a. In other words, the thermosetting resin 12b functions as an adhesive that bonds adjacent filler particles 12a to each other. In this embodiment, the filler particles 12a include not only substantially spherical filler particles 12a but also filler particles 12a having an irregular shape that is not spherical.

[0045] The plurality of filler particles 12a include filler particles 12a with different particle sizes. The particle sizes of the plurality of filler particles 12a contained in the molded section 12 fall within a predetermined range. In this embodiment, the particle sizes of the plurality of filler particles 12a fall within a range of, for example, 2 μm to 55 μm. The plurality of filler particles 12a with different particle sizes are dispersed and bonded together by a thermosetting resin 12b. Note that in this embodiment, the particle size of the filler particles 12a refers to a convenient value equivalent to the diameter of each particle when it is assumed to be a perfect sphere. In other words, the particle size of the filler particles 12a refers to the longest dimension of the filler particles 12a.

[0046] The grooves 13 are located on the surface 12c of the molded part 12 parallel to the first mounting surface 11a. The grooves 13 include a plurality of grooves 13. The grooves 13 are formed by irradiation with a laser L (see FIG. 10). The grooves 13 form characters representing information such as characters and figures indicating the model, serial number, size, manufacturer name, function, etc. of the piezoelectric vibration device 1. In this embodiment, the grooves 13 are located on the surface 12c of the molded part 12 parallel to the first mounting surface 11a of the substrate 11. In other words, the grooves 13 are located on the surface 12c of the molded part 12 perpendicular to the Z direction. The grooves 13 have a rectangular cross-sectional shape when viewed in the extension direction of the recess. Furthermore, the grooves 13 have a visible groove shape on the surface 12c.

[0047] Next, the groove portion 13 will be described with reference to Fig. 6 to Fig. 8. Fig. 7 is a cross-sectional view perpendicular to the stretching direction in which the filler particle 12a with the largest particle size is located in the center of the groove portion 13 formed in the molded portion 12 of the piezoelectric vibration device 1. Fig. 8 is a cross-sectional view perpendicular to the stretching direction in which the filler particle 12a with the largest particle size is located on the side surface 13b of the groove portion 13 formed in the molded portion 12 of the piezoelectric vibration device 1.

[0048] As shown in Figure 6, the thermosetting resin 12b located in the grooves 13 and bonding adjacent filler particles 12a together is sublimated by the heat of the laser L (see Figure 10). The filler particles 12a that were entirely contained within the grooves 13 are released from the grooves 13 by the sublimation of the thermosetting resin 12b. As a result, portions of the grooves 13 are formed that are recessed relative to the surface 12c of the molded part 12. The groove depth H of the grooves 13 is the length in the direction perpendicular to the surface 12c.

[0049] The groove width W of the groove portion 13 is the length in a direction perpendicular to the extension direction of the groove portion 13 and along the surface 12c. The groove width W is set to be 0.9 times or more the particle size of the largest filler particle 12a among the filler particles 12a contained in the molded portion 12. The groove depth H is set to be equal to or greater than the particle size of the smallest filler particle 12a among the filler particles 12a contained in the molded portion 12 and equal to or less than the groove width W.

[0050] The state of the bottom surface 13a and side surface 13b of the groove portion 13 machined by the laser L (see FIG. 10) differs from the state of the surface 12c of the molded portion 12 formed by the mold M (see FIG. 9). For example, the surface roughness of the bottom surface 13a of the groove portion 13 is approximately Ry15 μm. The surface roughness of the side surface 13b of the groove portion 13 is approximately Ry5 μm. The surface roughness of the surface 12c is approximately Ry10 μm. Therefore, the surface 12c and the bottom surface 13a and side surface 13b of the groove portion 13 are easily recognized as different parts due to differences in light reflection.

[0051] When the groove depth H of the groove portion 13 is equal to or less than the groove width W, the bottom surface 13a of the groove portion 13 is visible within a range of at least 45 degrees in each direction of the groove width W, based on a perpendicular line to the bottom surface 13a located at the center of the groove width W. In other words, the groove portion 13 is configured so that the bottom surface 13a is visible within a range of at least 45 degrees in the direction of the groove width W, where the viewpoint of a person recognizing characters, etc., is likely to be located.

[0052] 7, the grooves 13 have a groove width W that is 0.9 times or more the particle size of the largest filler particles 12a among the filler particles 12a contained in the molded section 12. In this embodiment, the groove width W is 49.5 μm, which is 0.9 times the size of the largest filler particles 12a, 55 μm, among the filler particles 12a contained in the molded section 12. The grooves 13 also have a groove depth H that is equal to or greater than the particle size (2 μm) of the smallest filler particles 12a among the filler particles 12a contained in the molded section 12 and is equal to or less than the groove width W (49.5 μm).

[0053] Filler particles 12a that are partially contained outside grooves 13 remain within grooves 13 because they are bonded to adjacent filler particles 12a outside grooves 13 by thermosetting resin 12b. For example, among the multiple filler particles 12a contained in molded section 12, some of the filler particles 12a with a maximum particle size (55 μm) that is larger than the groove width W of grooves 13 are located outside grooves 13. If the center of filler particle 12a with the maximum particle size is located in the center of groove 13 and the top of filler particle 12a with the maximum particle size is located on the same plane as surface 12c of molded section 12, the depth from surface 12c to the surface of filler particle 12a at the wall surface of groove 13 is approximately 0.6 times the radius of filler particle 12a.

[0054] Therefore, by setting the groove width W of the groove 13 to at least 0.9 times the particle size of the largest filler particle 12a among the filler particles 12a, it is possible to ensure a depression depth greater than half the radius of the largest filler particle 12a. As a result, the difference between the light reflection on the surface 12c of the groove 13 and the light reflection on the surface of the filler particle 12a near the wall surface becomes large.

[0055] 8, the grooves 13 have a groove depth H that is equal to or greater than the particle size of the smallest filler particle 12a among the filler particles 12a contained in the molded section 12 and equal to or less than 0.5 times the particle size of the largest filler particle 12a. In this embodiment, the groove depth H is 27.5 μm, which is equal to or greater than the particle size of the smallest filler particle 12a among the filler particles 12a contained in the molded section 12, 2 μm, less than the groove width W of 49.5 μm, and equal to or less than 0.5 times the particle size of the largest filler particle 12a, 55 μm. Note that the groove depth H is preferably equal to or greater than 10 μm to ensure good visibility of the grooves 13.

[0056] When the top of the filler particle 12a is located on the same plane as the surface 12c of the mold section 12, and the center of the filler particle 12a with the largest particle size is positioned so as to overlap one side surface 13b of the groove section 13 when viewed in a direction perpendicular to the surface 12c, the bottom surface 13a of the groove section 13 relative to the filler particle 12a is in contact with the outer edge of the filler particle 12a when viewed in a direction perpendicular to the bottom surface 13a.

[0057] Therefore, when viewed in a direction perpendicular to the bottom surface 13a, the bottom surface 13a is not located inside the outer edge of the filler particles 12a. Therefore, when viewed in a direction perpendicular to the bottom surface 13a, the bottom surface 13a is not covered by or shaded by the filler particles 12a, and is easily recognized as a part different from the surface 12c. This improves the visibility of the grooves 13 engraved by the laser L into the molded part 12, which is mainly composed of the filler particles 12a.

[0058] Next, using Figures 9 to 11, we will explain a manufacturing method for a piezoelectric vibration device 1 in which grooves 13 are formed in a molded portion 12 by irradiating it with a laser. Figure 9 is a schematic cross-sectional view showing a molding step S1 of the manufacturing method for a piezoelectric vibration device 1. Figure 10 is a schematic cross-sectional view showing the irradiation state of a laser L in a groove forming step S2 of the manufacturing method for a piezoelectric vibration device 1. Figure 11 is a schematic cross-sectional view showing an overlapping irradiation range D2 of a laser L in a groove forming step S2 of the manufacturing method for a piezoelectric vibration device 1. The manufacturing method for a piezoelectric vibration device 1 includes a molding step S1 and a groove forming step S2. It is assumed that a resonator 2 and an integrated circuit element 10 are mounted on a substrate 11.

[0059] As shown in FIG. 9, the molding process S1 is a process of forming a molded portion 12 by covering at least the vibrator 2 with a mixture of a plurality of filler particles 12a containing filler particles 12a of different particle sizes and a thermosetting resin 12b.

[0060] In the molding process S1, the substrate 11 on which the vibrator 2 and the integrated circuit element 10 are mounted is placed in a mold M. Next, the vibrator 2, the integrated circuit element 10, and the substrate 11 in the mold M are covered with a mixture of a plurality of filler particles 12a and a thermosetting resin 12b supplied into the mold M. Furthermore, the mixture is hardened in the mold M while covering the vibrator 2, the integrated circuit element 10, and the substrate 11. A molded portion 12 is formed in the vibrator 2, the integrated circuit element 10, and the substrate 11. Note that in this embodiment, the molding process S1 forms the molded portion 12 for a single substrate 11. However, the molding process S1 may also form the molded portion 12 simultaneously for an assembly in which a plurality of substrates 11 are connected in a matrix, and then singulate the assembly by a singulation process.

[0061] As shown in FIG. 10, the groove forming step S2 is a step of forming grooves 13 in the molded part 12 using a laser L. The grooves 13 are recesses formed in a surface 12c of the molded part 12 that is parallel to the first mounting surface 11a. The grooves 13 have a shape that, for example, represents any character or character string as a whole. In the groove forming step S2, the grooves 13 are formed using a YAG (Yttrium Aluminum Garnet) laser. The wavelength of the YAG laser is 1064 nm. The switching frequency of the YAG laser is 30 kHz. The scanning speed of the YAG laser is 150 mm / s.

[0062] In the groove forming step S2, a YAG laser (hereinafter simply referred to as "laser L") under predetermined conditions is irradiated onto the surface 12c of the molded part 12 to form the grooves 13. The laser L is irradiated so as to move back and forth across the surface 12c in a specific direction. Therefore, when the laser L moves back and forth in the X direction, the laser L is irradiated onto the portions of the grooves 13 extending in the X direction in the extension direction of the recesses. The laser L is irradiated onto the portions of the grooves 13 extending in the Y direction in the direction of the groove width W.

[0063] In the groove forming step S2, the surface 12c of the molded part 12 is irradiated with the laser L while being focused on a position closer to the light source S of the laser L than the surface 12c. Therefore, the laser L is not focused on the surface 12c (defocused). In this embodiment, the laser L is irradiated onto the surface 12c while being focused on a position a distance F away from the surface 12c closer to the light source S of the laser L.

[0064] In this embodiment, the distance F is set in the range of 0.100 mm to 0.200 mm. The irradiation diameter D of the defocused laser L on the surface 12c is larger than the irradiation diameter D (e.g., 20 μm) of the laser L focused on the surface 12c. Therefore, the energy per unit area in the irradiation region of the defocused laser L is smaller than the energy per unit area of ​​the focused laser L.

[0065] Furthermore, a groove formation range, which is a portion on the surface 12c of the molded part 12 where the groove 13 having the groove width W is formed, is irradiated with a laser beam L having an irradiation diameter D that is 0.5 times or more and less than 1 time the groove width W of the groove 13. To form the groove 13 having the groove width W, the laser beam L is irradiated, for example, along a portion in the groove formation range where one wall surface of the groove 13 is to be formed.

[0066] Furthermore, the laser beam L is irradiated along the portion of the groove formation area where the other wall surface of the groove 13 is to be formed. In this manner, the groove formation area is irradiated at least twice with the laser beam L. In this embodiment, the groove formation area, where the groove 13 having a groove width W of 49.5 μm is to be formed, is irradiated twice with the laser beam L having an irradiation diameter D of 27 μm, which is 0.55 times the groove width W, for example.

[0067] 11, the laser beam L is irradiated so that a part of the irradiation diameter D overlaps when viewed in a direction perpendicular to the surface 12c. The overlapping irradiation range D2, which is the area where the laser beam L is irradiated in an overlapping manner, becomes wider as the irradiation diameter D increases. As the first irradiation L1, the laser beam L is irradiated along the portion where one wall surface of the groove portion 13 is formed in the groove portion formation range.

[0068] Next, as a second irradiation L2, the laser L is irradiated along the portion of the groove formation area where the other wall surface of the groove 13 is to be formed. Thus, the groove 13 is formed with high precision, with the unevenness of the bottom surface 13a suppressed and the side surface 13b prevented from excessive sublimation. At this time, the overlapping irradiation area D2 of the first irradiation L1 and the second irradiation L2 of the laser L is a range of 4.5 μm in the direction of the groove width W at the center of the groove 13's groove width W when viewed in a direction perpendicular to the surface 12c of the molded section 12.

[0069] The overlapping irradiation range D2 between the first laser L irradiation L1 and the second laser L irradiation L2 becomes wider as the irradiation diameter D of the laser L increases due to defocusing. Also, the energy per unit area input from the laser L in the overlapping irradiation range D2 becomes smaller. Therefore, it is possible to reduce the irregularities formed by the overlapping irradiation of the laser L on the bottom surface 13a of the groove portion 13.

[0070] This improves the light reflectivity of the bottom surface 13a of the groove portion 13, making it easier to visually recognize the surface 12c of the molded portion 12 and the bottom surface 13a of the groove portion 13 as different portions. This improves the visibility of the portion engraved by the laser L on the molded portion 12, which is mainly composed of filler particles 12a. Furthermore, defocusing the laser L reduces the energy per unit area of ​​the irradiation diameter D of the laser L, thereby suppressing damage to the vibrator 2 and the integrated circuit element 10, cutting of the wires 10b, and the like caused by the heat of the laser L.

[0071] [Other embodiments] In the above-described embodiment, the molded part 12 is a mixture of approximately 90% filler particles 12a, approximately 10% thermosetting resin, and other minor components. However, as long as the molded part contains filler particles, the ratio of the filler particles to the thermosetting resin may be any ratio.

[0072] In the above embodiment, the filler particles 12a are made of silica glass, but may be made of calcium carbonate, talc, a clay compound, or the like.

[0073] In the above-described embodiment, the thermosetting resin 12b is made of epoxy resin, but the thermosetting resin may be silicone resin, urethane resin, or the like.

[0074] In the above-described embodiment, the particle size of the plurality of filler particles 12a is in the range of 2 μm to 55 μm. However, the particle size of the filler particles may be less than 2 μm. The particle size of the filler particles may be greater than 55 μm. The lower limit of the particle size range of the filler particles may be greater than 2 μm. The upper limit of the particle size range of the filler particles may be less than 55 μm.

[0075] In the above-described embodiment, the piezoelectric vibration device 1 has the vibrator 2 and the integrated circuit element 10 mounted on the substrate 11. However, the piezoelectric vibration device may have at least the vibrator mounted on the substrate and molded.

[0076] In the above-described embodiment, the piezoelectric vibration device 1 has the vibrator 2 and the integrated circuit element 10 mounted side by side on the substrate 11. However, the piezoelectric vibration device may have a configuration in which electronic components are mounted on a vibrator mounted on a substrate.

[0077] In the above-described embodiment, the vibrator 2 is electrically connected to the wiring pattern of the substrate 11 by the wire 10b. However, the vibrator may have a configuration in which the vibrator mounting terminal is electrically connected to the connection terminal of the substrate.

[0078] In the above-described embodiment, the vibrator 2 is a sandwich-structure vibrator in which the piezoelectric diaphragm 3 is sandwiched between the first sealing member 6 and the second sealing member 7. However, the vibrator may be a surface-mount structure vibrator in which the piezoelectric diaphragm is housed inside a ceramic package with an opening, and the opening is airtightly sealed with a lid. It may also be a tuning-fork crystal vibrator or an AT-cut or SC-cut crystal vibrator.

[0079] In the above embodiment, the grooves 13 are formed in the molded part 12 by a YAG laser. However, the grooves may also be formed by a CO2 laser, a fiber laser, a UV laser, or the like. The YAG laser is irradiated at a switching frequency of 30 kHz and a scanning speed of 150 mm / s. However, the settings of the YAG laser may be changed as desired depending on the processing conditions.

[0080] In the above-described embodiment, the groove 13 has a rectangular groove shape when viewed in the extension direction of the recess. However, the groove may have a groove shape other than a rectangular shape, such as a semicircular, trapezoidal, or triangular shape, when viewed in the extension direction of the recess.

[0081] Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and it is possible to appropriately modify the above-described embodiments within the scope of the spirit of the present invention. [Explanation of symbols]

[0082] 1. Piezoelectric vibration device 2 oscillators 3 Piezoelectric diaphragm 4 Vibration unit 4a Excitation electrode 4b Notch 5 Bonding material 6 First sealing member 7 Second sealing member 10 Integrated circuit elements 10a Integrated circuit element mounting terminal 10b wire 11 Circuit Board 11a First mounting surface 11b Second mounting surface 11d Connection terminal 11g External connection terminal 11h Joint surface 11j Recess 11p wire connection terminal 12 Mold section 12a Filler particles 12b Thermosetting resin 12c surface 13 Groove 13a Bottom 13b Side W Groove width H Groove depth M mold L Laser S light source L1 First irradiation L2 Second irradiation D Irradiation diameter D2 overlapping irradiation range S1 Molding Process S2 Groove formation process

Claims

1. A substrate; a piezoelectric vibrator mounted on the substrate; an electronic component mounted on the substrate; A piezoelectric vibration device having a molded portion that is made of a mixture of at least a plurality of filler particles and an insulating resin and that covers at least the piezoelectric vibrator, The mold part is A plurality of filler particles having different particle sizes are bonded by an insulating resin, and the surface has grooves formed by laser irradiation, The groove portion is The groove width is 0.9 times or more the particle diameter of the largest filler particle among the filler particles contained in the mold part. Piezoelectric vibration device.

2. 2. The piezoelectric vibration device according to claim 1, The groove portion is A groove depth equal to or less than the groove width. Piezoelectric vibration device.

3. 2. The piezoelectric vibration device according to claim 1, The groove portion is The groove depth is 0.5 times or less the particle diameter of the largest filler particle among the filler particles contained in the mold part. Piezoelectric vibration device.

4. A method for manufacturing a piezoelectric vibrating device having a substrate, a piezoelectric vibrator mounted on the substrate, an electronic component mounted on the substrate, and a molded portion covering at least the piezoelectric vibrator, wherein a groove is formed in the molded portion by irradiating the molded portion with a laser, a molding step of covering at least the piezoelectric vibrator with a mixture of a plurality of filler particles including at least filler particles with different particle sizes and an insulating resin to form the molded portion; a groove forming step of forming grooves having a groove width that is 0.9 times or more the particle diameter of the largest filler particle among the filler particles contained in the molded part by focusing a laser on a side closer to the laser light source than the surface of the molded part, In the groove forming step, the irradiation diameter of the laser irradiated onto the surface of the mold part is: The groove width is 0.5 times or more and less than 1 time, A method for manufacturing a piezoelectric vibration device.

5. 5. The method for manufacturing a piezoelectric vibration device according to claim 4, In the groove forming step, the laser The surface of the mold part is irradiated with the light so that the irradiation diameters partially overlap when viewed in a direction perpendicular to the surface of the mold part. A method for manufacturing a piezoelectric vibration device.

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