JP2007235707A - Piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric device which is reduced in height, reduced in cost and stably manufactured. <P>SOLUTION: A piezoelectric device 10 is configured so that a recess 30 is formed on the tear side of a vibrator package 24 in which a piezoelectric vibrator 22 is packaged, an IC chip 40 vibrating the piezoelectric vibrator 22 is mounted to the recess 30, a lead terminal 50 is arranged adjacently to the vibrator package 24, the IC chip 40 and the lead terminal 50 are conducted, and inner leads of the IC chip 40 and the lead terminal 50 are sealed with a molding material 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric device, and more particularly to a piezoelectric device having a configuration in which a built-in component is sealed with a molding material.

  A piezoelectric device includes a piezoelectric vibrator, an integrated circuit (IC) chip, and a lead terminal, and a built-in component such as the piezoelectric vibrator is sealed with a molding material. The specific configuration is as follows. That is, the piezoelectric vibrator has a configuration in which a piezoelectric vibrating piece is mounted in a package and an external terminal is provided on the back surface of the package. The IC chip is provided with a pad on its main surface and bonded to the back surface of the piezoelectric vibrator. At this time, the surface opposite to the main surface of the IC chip is bonded to the piezoelectric vibrator.

A plurality of lead terminals are joined to the back surface of the piezoelectric vibrator. Each lead terminal and the pad provided on the IC chip are electrically connected by a wire, and the external terminal and the pad provided on the piezoelectric vibrator are electrically connected by a wire. The periphery of the inner lead portion of the piezoelectric vibrator, IC chip, wire, and lead terminal is sealed with a molding material. The outer lead portion of the lead terminal protruding from the mold material is bent downward, and a mounting terminal is formed at the end thereof. Patent Document 1 discloses such a piezoelectric device.
JP 2004-297770 A (FIG. 1)

  In recent years, as electronic devices have been reduced in size, piezoelectric devices mounted thereon are also required to be thinner. However, in the piezoelectric device having an IC chip mounted on the back surface of the piezoelectric vibrator described above, it is difficult to reduce the height because the piezoelectric vibrator and the IC chip are stacked.

  Further, in the piezoelectric device having this configuration, a step is formed from the back surface of the piezoelectric vibrator to the main surface of the IC chip. Therefore, the external terminals provided on the piezoelectric vibrator and the pads provided on the main surface of the IC chip are connected with wires. When conducting, the wire loop had to be raised and this made the wire longer. For this reason, when gold is used as the material of the wire, the manufacturing cost becomes high. Further, when the periphery of the piezoelectric vibrator or the like is sealed with a molding material, since the surface area of the wire is large, resistance easily occurs when the molding material flows. At this time, the wires are deformed by the flow of the molding material, and there is a possibility that the wires are in contact with each other or the wires are disconnected.

  In addition, since a step is generated by the IC chip in the piezoelectric device, and the distance between the external terminal provided on the piezoelectric vibrator and the pad provided on the IC chip is short, wires that conduct these are bonded by a reverse bonding method. Had to do. In this reverse bonding method, a bump is first formed on the pad, and then one end of the wire is bonded to the external terminal, and then the other end of the wire is bonded to the bump formed on the pad. It was hanging.

  Further, since the planar sizes of the IC chip and the piezoelectric vibrator are miniaturized, high accuracy is required for mounting accuracy when the IC chip is mounted on the piezoelectric vibrator. For example, 50 μm is required for the mounting accuracy. However, the IC chip is bonded to the back surface of the piezoelectric vibrator by an adhesive, but it may be displaced after the adhesive is cured after being mounted on the back face of the piezoelectric vibrator, and the mounting accuracy may not be satisfied. is there. At this time, there is a possibility that the wire that conducts the pad and the lead terminal or the wire that conducts the pad and the external terminal cannot be reliably bonded. In addition, if the IC chip slips out of the outer shape of the piezoelectric vibrator, the die used when sealing the piezoelectric vibrator or the like with the molding material and the IC chip come into contact with each other, and the die is damaged. There is a risk of causing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric device that has a reduced height and is stably manufactured at a low cost.

  In the piezoelectric device according to the present invention, a recess is provided on the back surface of the vibrator package in which the piezoelectric vibrating piece is mounted, and an IC chip for oscillating the piezoelectric vibrating piece is mounted in the recess, and the lead terminal is adjacent to the vibrator package. And the IC chip and the lead terminal are electrically connected, and the vibrator package, the IC chip, and the inner lead portion of the lead terminal are sealed with a molding material. In this case, the IC chip and the lead terminal are electrically connected through a wire provided inside the mold material.

  Since the IC chip is mounted in the recess, the piezoelectric device can be reduced in height. In addition, since the step generated between the back surface of the vibrator package and the top surface of the IC chip is smaller than in the conventional case, the loop height of the wire can be reduced and the length of the wire can be shortened. Therefore, since the amount of wire used is reduced, the piezoelectric device can be manufactured at low cost. Further, since the length of the wire is short, it becomes difficult to receive resistance to the flow of the molding material when the vibrator package or the like is sealed with the molding material, and it is possible to prevent the occurrence of the defect of the wire. Further, since the movement of the IC chip is restricted when the IC chip is mounted in the recess, it is possible to prevent the occurrence of manufacturing defects caused by the movement of the IC chip. Therefore, the piezoelectric device can be manufactured stably.

  The piezoelectric device according to the present invention is characterized in that the back surface of the vibrator package and the top surface of the IC chip are in the same plane. The piezoelectric device according to the present invention is characterized in that the upper surface of the lead terminal and the rear surface of the vibrator package are in the same plane. As a result, the piezoelectric device can be made shorter, the cost can be reduced by reducing the amount of wire used, and the piezoelectric device can be manufactured stably.

  The lead terminals described above are characterized by being bonded to the back surface of the vibrator package. This makes it difficult for the lead terminal to come out of the molding material, and a highly reliable piezoelectric device can be manufactured.

  The piezoelectric device according to the present invention is characterized in that a terminal recess is provided on the back surface of the vibrator package, a lead terminal is disposed in the terminal recess, and the vibrator package and the lead terminal are joined. Yes. This makes it difficult for the lead terminal to come out of the mold material, so that a highly reliable piezoelectric device can be manufactured, and a low-profile piezoelectric device can be manufactured stably at low cost.

  The external terminals provided on the back surface of the vibrator package are arranged along one side forming the outer shape of the vibrator package. Thereby, the planar size of the vibrator package can be reduced.

  The piezoelectric device according to the present invention is characterized in that a taper is provided around the recess. Thereby, it becomes easy to put the IC chip into the recess, and the piezoelectric device can be manufactured stably.

  Hereinafter, the best embodiment of the piezoelectric device according to the present invention will be described. FIG. 1 is an explanatory diagram of a piezoelectric device. Here, FIG. 1A is an explanatory view of the piezoelectric device in plan view, and FIG. 1B is a cross-sectional view of the piezoelectric device. Note that in FIG. 1B, some of the wires are omitted. FIG. 2 is a sectional view of the piezoelectric vibrator.

  The piezoelectric device 10 shown in FIG. 1 includes a piezoelectric vibrator 20, an IC chip 40, lead terminals 50, and wires 14, and the periphery of these piezoelectric vibrators 20 and the like is sealed with a molding material 16. Specifically, the piezoelectric vibrator 20 has a vibrator package 24 in which a piezoelectric vibrating piece 22 is mounted. The vibrator package 24 has a package base 24a and a lid 24b.

  The package base 24a shown in FIG. 2A is provided with a resonator element containing portion 26 that opens toward the surface (the lower side in the drawing in FIG. 2A). A piezoelectric vibrating piece 22 that oscillates when an electric signal is supplied and outputs a signal having this oscillation frequency is mounted on the vibrating piece housing portion 26. The lid 24b is joined to the surface of the package base 24a via a seam ring 28 or the like, so that the vibration piece housing portion 26 is closed. Thereby, the piezoelectric vibrating piece 22 is sealed. The piezoelectric vibrating piece 22 may be a piezoelectric vibrating piece such as an AT cut, a tuning fork type piezoelectric vibrating piece, a surface acoustic wave resonance piece, or the like. The package base 24a may have a flat surface 36 as shown in FIG. In this case, the piezoelectric vibrator 20 has a configuration in which the piezoelectric vibrating piece 22 is mounted on the surface 36 of the package base 24a, and the lid 24b is provided via a seam ring 28 or the like provided around the piezoelectric vibrating piece 22.

  Further, a recess 30 for mounting the IC chip 40 is provided on the back surface 29 of the vibrator package 24 (package base 24a). The planar size of the recess 30 only needs to be large enough to accommodate the IC chip 40, and is determined in consideration of the size of the IC chip 40 in the planar direction, mounting accuracy, and the like. Further, the depth of the recess 30 is sufficient if the IC chip 40 can be inserted. Preferably, the back surface 29 of the vibrator package 24 and the main surface 42 (upper surface) of the IC chip 40 are in the same plane. It is good to be arranged (become the same height).

  Further, external terminals 32 are provided on the back surface 29 of the vibrator package 24. The external terminal 32 is electrically connected to the piezoelectric vibrating piece 22. As shown in FIG. 1A, the external terminal 32 is preferably provided along one side of the sides forming the outer shape of the vibrator package 24. Thereby, the planar size of the vibrator package 24 can be reduced.

  The IC chip 40 shown in FIG. 1 has a plurality of pads 44 on its main surface 42. The IC chip 40 has a smaller planar size than the vibrator package 24. The IC chip 40 only needs to include at least a circuit that oscillates the piezoelectric vibrator 20 (piezoelectric vibrating piece 22), a voltage control circuit that changes the oscillation frequency by controlling the voltage, and the periphery of the piezoelectric vibrating piece 22. A temperature compensation circuit or the like that corrects the frequency temperature characteristic so as to output a constant oscillation frequency regardless of the temperature can also be provided. Such an IC chip 40 is mounted in the recess 30 with the surface opposite to the main surface 42 facing the vibrator package 24.

  A plurality of lead terminals 50 are arranged around the piezoelectric vibrator 20 (vibrator package 24). That is, each lead terminal 50 is disposed adjacent to the side surface of the piezoelectric vibrator 20. The lead terminal 50 is preferably arranged so that the upper surface 50a (the surface facing the upper side in FIG. 1B) is in the same plane as the back surface 29 of the piezoelectric vibrator 20. The lead terminal 50 is a mounting lead terminal 52 for forming the mounting terminal 52c, for supplying a program and data to the IC chip 40, and for checking whether the piezoelectric device 10 is operating normally. The lead terminal 54 for writing and the lead terminal 56 for joining joined to the piezoelectric vibrator 20 by the joining material 58 may be used. The wire 14 is bonded to the lead terminal 50 and the pad 44 provided on the IC chip 40, and the wire 14 is bonded to the external terminal 32 and the pad 44 provided on the piezoelectric vibrator 20 so that they are electrically connected. is doing.

  Then, the piezoelectric vibrator 20 (the vibrator package 24), the IC chip 40, the wires 14, and the inner lead portions 52a, 54a, and 56a of the lead terminals 50 (joint locations between the vibrator package 24 and the lead terminals 50, and the lead terminals 50). The molding material 16 is provided around the portion where the wire 14 is bonded to the wire. Out of the lead terminals 50 protruding from the molding material 16, the outer lead portion 52b of the mounting lead terminal 52 is bent below the molding material 16, and the tip portion thereof becomes the mounting terminal 52c. The mounting terminal 52c serves as a joint between the piezoelectric device 10 and the circuit board when the piezoelectric device 10 is mounted on the circuit board constituting the electronic apparatus. In the case shown in FIG. 1, the mounting lead terminal 52 is bent to the side where the lid 24b of the piezoelectric vibrator 20 is provided. Of the lead terminals 50 protruding from the molding material 16, the writing lead terminal 54 and the joining lead terminal 56 are cut at the surface of the molding material 16.

  Next, a method for manufacturing the piezoelectric device 10 will be described. FIG. 3 is a flowchart illustrating the manufacturing process of the piezoelectric device. First, the package base 24a is manufactured (S100). The package base 24a is mounted with the recess 30 and the piezoelectric vibrating piece 22 on which the IC chip 40 shown in FIG. 2A is mounted, for example, by laminating a frame-shaped insulating sheet on both sides of a flat insulating sheet. The vibration piece accommodating portion 26 is formed. In order to provide the recess 30 on the back surface 29 of the package base 24a, a flat insulating sheet and a frame-shaped sheet may be stacked. The thickness after stacking these sheets is the same as that of a conventional piezoelectric vibrator. The thickness is about the same as the thickness of the sheet constituting the bottom surface of the package base used. Further, for example, after metallized printing is performed on the package base 24a, plating is performed on the metallized so that the external terminals 32 and the terminals 34 for mounting the piezoelectric vibrating reeds 22 (see FIG. 2), and wirings for electrically connecting them. A pattern (not shown) is formed.

  Then, the piezoelectric vibrating piece 22 is mounted on the terminal 34 formed on the surface of the package base 24a (S110). Further, the lid 24b is joined to the surface of the package base 24a (S120), and the piezoelectric vibrating piece 22 is hermetically sealed. The IC chip 40 is mounted in the recess 30 of the piezoelectric vibrator 20 formed in this way (S130). At this time, the IC chip 40 and the piezoelectric vibrator 20 may be joined with an adhesive.

  Thereafter, the lead terminal 50 is disposed around the piezoelectric vibrator 20. At this time, it is preferable to arrange the lead terminal 50 so that the upper surface 50a of the lead terminal 50 and the rear surface 29 of the piezoelectric vibrator 20 have the same height (in the same plane). Each lead terminal 50 is connected to one frame. For this reason, all the lead terminals 50 are disposed around the piezoelectric vibrator 20 in one operation. Of the lead terminals 50, the joining lead terminal 56 is joined to the piezoelectric vibrator 20 by the joining material 58 (S140). In some embodiments, the mounting lead terminal 52 and the writing lead terminal 54 may be bonded to the piezoelectric vibrator 20 with a bonding material.

  Thereafter, wire bonding is applied to the external terminal 32 provided on the piezoelectric vibrator 20 and the pad 44 provided on the IC chip 40, and the mounting lead terminal 52, the write lead terminal 54, and the pad 44 are connected. Wire bonding is performed, and these are conducted by the wire 14 (S150). At this time, if the main surface 42 of the IC chip 40 and the back surface 29 of the piezoelectric vibrator 20 are at the same height (in the same plane), there is no need to make the loop of the wire 14 higher than in the conventional case. If the main surface 42 of the IC chip 40 and the upper surface 50a of the lead terminal 50 are at the same height (in the same plane), there is no need to increase the loop of the wire 14. In this case, the wire 14 can be bonded by a normal bonding method. That is, after one end of the wire 14 is bonded to the pad 44 of the IC chip 40, the other end of the wire 14 may be bonded to the external terminal 32 or the lead terminal 50 of the piezoelectric vibrator 20.

  Even if the main surface 42 of the IC chip 40 and the back surface 29 of the piezoelectric vibrator 20 are not in the same plane, the IC chip 40 is mounted in the recess 30 provided in the vibrator package 24, so that the piezoelectric vibration The distance from the back surface 29 of the child 20 to the main surface 42 of the IC chip 40 is shorter than the conventional one. For this reason, since it is not necessary to make the loop of the wire 14 high as in the prior art, a normal bonding method can be used, and the length of the bonded wire 14 is shortened.

  Thereafter, the piezoelectric vibrator 20, the IC chip 40, the wire 14, and the inner lead portions 52a, 54a, and 56a of the lead terminal 50 are sealed with the molding material 16 (S160). For example, this may be a process in which the piezoelectric vibrator 20 or the like is disposed in a mold, the molding material 16 is poured into the mold, and the molding material 16 is provided around the piezoelectric vibrator 20 or the like.

  Thereafter, the mounting terminal 52c is formed (S170). Specifically, the outer lead portion 52b of the mounting lead terminal 52 is bent below the molding material 16, and the mounting terminal 52c is formed on the lower surface of the tip portion. The write lead terminal 54 has a probe applied to a portion protruding from the molding material 16, and a program and data are supplied from the probe, and the program or the like is connected to the IC chip via the write lead terminal 54 and the wire 14. 40. Further, a probe is applied to the write lead terminal 54, and it is inspected whether or not the piezoelectric device 10 is operating normally with an inspection device connected to the probe.

  Then, the write lead terminal 54 is cut along the surface of the molding material 16 when the input of a program or the like and the operation check of the piezoelectric device 10 are completed. Similarly, the joining lead terminal 56 is also cut along the surface of the molding material 16. The write lead terminal 54 may not be provided depending on the embodiment. The write lead terminal 54 may have either a function for inputting a program or the like and a function used for inspection. Thereby, the piezoelectric device 10 is manufactured.

  In such a piezoelectric device 10, a part of the back surface 29 of the piezoelectric vibrator 20 (vibrator package 24) is thinned to provide a recess 30, and the IC chip 40 is mounted in the recess 30. Can be turned down.

  Further, by providing the concave portion 30 on the back surface 29 of the piezoelectric vibrator 20, the step formed by the main surface 42 of the IC chip 40 and the back surface 29 of the piezoelectric vibrator 20 can be eliminated, or a step can be formed as compared with the conventional case. Can be small. For this reason, the loop of the wire 14 for conducting the piezoelectric vibrator 20 and the IC chip 40 can be lowered, and the length of the wire 14 can be shortened. For this reason, the piezoelectric device 10 can be reduced in height and the manufacturing cost can be reduced.

  Further, since the wire 14 is short, the surface area of the wire 14 can be reduced. When manufacturing the piezoelectric device 10, even if the molding material 16 is poured around the piezoelectric vibrator 20 or the like, the wire 14 can be made difficult to be flowed by the molding material 16, and the wires 14 are in contact with each other or the wires 14 are disconnected. The occurrence of defects such as these can be prevented. Therefore, the piezoelectric device 10 can be manufactured stably.

  If the main surface 42 of the IC chip 40, the back surface 29 of the piezoelectric vibrator 20 and the upper surface 50a of the lead terminal 50 are arranged at the same height, the loop of the wire 14 can be made lower, so that the piezoelectric device 10 is formed. The height can be further reduced. When the thickness of the piezoelectric device 10 described in the present embodiment is compared with the thickness of the conventional piezoelectric device, the piezoelectric device 10 described in the present embodiment can be reduced by about 20% compared to the conventional device. It was.

  Further, since the wire 14 can be bonded by a normal bonding method, the wire bonding work time can be shortened. Further, during the manufacture of the piezoelectric device 10, after the IC chip 40 is mounted in the recess 30, the movement of the IC chip 40 is restricted by the recess 30. For this reason, even if the IC chip 40 is displaced between the time when it is mounted in the recess 30 of the piezoelectric vibrator 20 and the time when the adhesive is cured, the mounting accuracy is not satisfied. Therefore, it is possible to prevent the occurrence of defects during the manufacture of the piezoelectric device 10, and the piezoelectric device 10 can be manufactured stably.

  As a modification of the piezoelectric device 10 described above, the lead terminal 50 may be joined to the back surface 29 of the piezoelectric vibrator 20. As a result, the bonding strength between the lead terminal 50 and the piezoelectric vibrator 20 can be improved.

  The lead terminal 50 may be disposed in a recess for the lead terminal 50 (terminal recess) provided on the back surface 29 of the piezoelectric vibrator 20. FIG. 4 is an enlarged explanatory view of a part of the piezoelectric vibrator and the lead terminal provided with the terminal recess. 4A is a plan view and FIG. 4B is a side view. The terminal recess 60 is provided on the outer peripheral portion of the back surface 29 of the piezoelectric vibrator 20 and may have a planar shape that follows the shape of the lead terminal 50. Further, it is preferable that the terminal recessed portion 60 has such a depth that the upper surface 50a of the lead terminal 50 and the back surface 29 of the piezoelectric vibrator 20 are flush with each other when the lead terminal 50 is joined. With such a configuration, the loop of the wire 14 (not shown in FIG. 4) for conducting the lead terminal 50 and the IC chip 40 (not shown in FIG. 4) can be lowered, and the lead terminal 50 and The bonding strength of the piezoelectric vibrator 20 can be improved.

  As a modification of the piezoelectric device 10, as shown in FIG. 5, the recess 30 provided in the vibrator package 24 may be cut out. In this case, the package base 24a may be formed by laminating, for example, a flat insulating sheet and an insulating sheet in which a groove (notch) is formed. As a result, a notch-shaped recess 30 is formed on the back surface 29 of the transducer package 24.

  As a modification of the piezoelectric device 10, the side surface of the recess 30 provided in the piezoelectric vibrator 20 may be tapered. In other words, the recess 30 may have a shape in which the area of the opening surface of the recess 30 (the back surface 29 side of the piezoelectric vibrator 20) is large and the area of the bottom surface of the recess 30 is narrow. As a result, when the IC chip 40 is mounted in the recess 30, the IC chip 40 is easily guided into the recess 30 due to the tapered shape, and the IC chip 40 can be reliably mounted in the recess 30.

  As a modification of the piezoelectric device 10, the IC chip 40 may be mounted in the recess 30 using flip bonding. In this case, the package base 24 a extends from the bump provided on the bottom surface of the recess 30 to the vicinity of the lead terminal 50 (the mounting lead terminal 52 or the writing lead terminal 54) disposed adjacent to the side surface of the piezoelectric vibrator 20. An extended wiring pattern is formed. The package base 24a is formed with a wiring pattern for electrically connecting the bump and the piezoelectric vibrating piece 22. Then, the lead terminal 50 and the piezoelectric vibrator 20 may be joined by a conductive joining material so that the lead terminal 50 and the wiring pattern are electrically connected. The IC chip 40 is mounted in the recess 30 with the main surface 42 provided with the pads 44 facing the piezoelectric vibrator 20, and the bumps and the pads 44 are electrically connected. The recess 30 preferably has such a depth that the surface (upper surface) opposite to the main surface 42 of the IC chip 40 and the back surface 29 of the piezoelectric vibrator 20 form the same surface. Thereby, the piezoelectric device 10 can be further reduced in height.

It is explanatory drawing of a piezoelectric device. It is sectional drawing of a piezoelectric vibrator. It is a flow explaining the manufacturing process of a piezoelectric device. It is explanatory drawing which expanded some piezoelectric vibrators and lead terminals which provided the concave part for terminals. It is a perspective view of a piezoelectric vibrator having a notch-shaped recess.

Explanation of symbols

10 ......... Piezoelectric device, 14 ......... Wire, 16 ......... Mold material, 20 ......... Piezoelectric vibrator, 22 ......... Piezoelectric vibrator, 24 ......... Vibrator package, 30 ......... Recess, 32... External terminal 40... IC chip 50... Lead terminal 60.

Claims (7)

A recess is provided on the back surface of the vibrator package in which the piezoelectric vibrating piece is mounted,
An IC chip that oscillates the piezoelectric vibrating piece is mounted in the recess,
A lead terminal is disposed adjacent to the vibrator package, and the IC chip and the lead terminal are electrically connected.
The vibrator package, the IC chip, and the inner lead portion of the lead terminal are sealed with a molding material,
A piezoelectric device characterized by that.   The piezoelectric device according to claim 1, wherein a back surface of the vibrator package and an upper surface of the IC chip are in the same plane.   The piezoelectric device according to claim 1, wherein an upper surface of the lead terminal and a rear surface of the vibrator package are in the same plane.   2. The resonator package according to claim 1, wherein a terminal recess is provided on a back surface of the vibrator package, the lead terminal is disposed in the terminal recess, and the vibrator package and the lead terminal are joined. 4. The piezoelectric device according to any one of 3.   The piezoelectric device according to claim 1, wherein the lead terminal is bonded to a back surface of the vibrator package.   6. The piezoelectric device according to claim 1, wherein the external terminal provided on the back surface of the vibrator package is disposed along one side forming an outer shape of the vibrator package.   The piezoelectric device according to claim 1, wherein a taper is provided around the recess.

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