JP2024088102A - Piezoelectric Oscillator - Google Patents

Abstract

To provide a piezoelectric oscillator of H type structure that includes a vibrator chamber having a recess to accommodate a vibrator and a semiconductor chamber having a recess to accommodate a semiconductor element, with which it is made easy to apply a coating of resin to a portion below the semiconductor element.SOLUTION: Provided is a piezoelectric oscillator comprising: a package in which a vibrator chamber having a recess to accommodate a piezoelectric vibrator and a semiconductor chamber having a recess to accommodate a semiconductor element are joined back to back; the piezoelectric vibrator that is accommodated in the vibrator chamber; the semiconductor element that is accommodated in the semiconductor chamber; a resin that is filled between the bottom of the semiconductor chamber and the semiconductor element; and a lid member that seals the vibrator chamber. The semiconductor element is of a rectangular shape in a plan view, and the semiconductor element has a notch in a surface opposite the surface joined to the semiconductor chamber, the notch being cut over two sides of the semiconductor element.SELECTED DRAWING: Figure 1

Description

The present invention relates to a piezoelectric oscillator with an H-shaped structure that includes a vibrator chamber with a recess for accommodating a vibrator and a semiconductor chamber with a recess for accommodating a semiconductor element.

Surface mount type piezoelectric oscillators are small, lightweight, and low-profile, and are used in many portable devices. One type has a concave transducer chamber that houses the piezoelectric transducer, and a concave semiconductor chamber that houses the semiconductor element, with the transducer chamber and semiconductor chamber joined back-to-back, and the cross section resembles the letter H (called an H-shaped structure or two-chamber structure).
In the case of a piezoelectric oscillator with an H-shaped structure, the semiconductor element is mounted in the semiconductor chamber by face-down bonding. The semiconductor chamber is not sealed with a cover member or the like, and the mounted semiconductor element is left exposed when the piezoelectric oscillator is completed as a product. In order to protect the exposed semiconductor element, resin is dripped onto the surface of the semiconductor element and allowed to flow under the semiconductor element, filling the gap between the semiconductor element and the bottom of the semiconductor chamber. This strengthens the bond between the semiconductor element and the bottom of the semiconductor chamber, making it resistant to external vibrations and shocks. In addition, the solder flux used to mount the piezoelectric oscillator on a mobile device or the like can get in between the semiconductor element and the bottom of the semiconductor chamber, causing the frequency to deviate from the specified frequency, but the resin can prevent this.

Patent Document 1 describes a method of applying resin to a piezoelectric oscillator with an H-shaped structure. In this method, a protrusion hole for injecting resin is provided on each of the short side walls of a recess that is rectangular in plan view, and the resin is dripped from the protrusion hole onto the semiconductor (paragraphs 16 and 17 of Patent Document 1). These protrusion holes make it possible to apply resin underneath the semiconductor element even in the case of a small piezoelectric oscillator (paragraph 18 of Patent Document 1).

JP 2003-264429 A

However, while piezoelectric oscillators are becoming smaller, the size of the resin application nozzle remains the same, making it difficult to provide protruding holes for resin injection in each of the short side walls of the semiconductor chamber. Another possible application method is to use the gap between one side of the wall surrounding the recess of the semiconductor chamber and the semiconductor element as the center of resin application, and allow the resin applied to this gap to flow under the semiconductor element. However, with this method, as piezoelectric oscillators become smaller, the distance between the external connection terminals at the four corners of the outer wall becomes narrower, and the resin applied to the outer wall ends up being applied to the external connection terminals, which reduces the wettability of the solder when the piezoelectric oscillator is mounted on a board for an electronic device or the like at the customer's site.

The present invention has been made in consideration of the above points, and therefore the purpose of this application is to provide a piezoelectric oscillator with an H-shaped structure that includes a vibrator chamber with a recess for accommodating a vibrator and a semiconductor chamber with a recess for accommodating a semiconductor element, and that makes it easier to apply resin under the semiconductor element.

In order to achieve this object, the piezoelectric oscillator of the present invention includes a package in which a transducer chamber having a recess for accommodating a piezoelectric vibrator and a semiconductor chamber having a recess for accommodating a semiconductor element are joined back to back, the piezoelectric vibrator accommodated in the transducer chamber, the semiconductor element accommodated in the semiconductor chamber, resin filled between the bottom of the semiconductor chamber and the semiconductor element, and a lid member sealing the transducer chamber,
The semiconductor element has a rectangular shape in a plan view,
the semiconductor element has a notch on a surface opposite to a surface bonded to the semiconductor chamber;
the notch is provided so as to extend over two sides of the semiconductor element;
It is characterized by:
The two sides referred to here may be two parallel sides or two adjacent sides among the four sides of the quadrangle.
The notch may be one or more.

The piezoelectric oscillator of this invention uses a semiconductor element with a slit, which allows the resin applied dropwise to the surface of the semiconductor element to easily flow down the slit to underneath the semiconductor element, allowing the required amount of resin to be filled underneath the semiconductor element. This prevents solder flux from getting under the semiconductor element when the piezoelectric oscillator is soldered onto another device, preventing frequency deviations caused by flux. In addition, because this invention does not involve any special packaging design, it can be adapted to future advances in the miniaturization of piezoelectric oscillators.

1A, 1B, and 1C are diagrams for explaining a piezoelectric oscillator according to an embodiment of the present invention. 1A, 1B, and 1C are diagrams showing a process of applying a resin dropwise to a piezoelectric oscillator according to an embodiment of the present invention. 1A and 1B are diagrams showing how resin flows under a semiconductor element in a piezoelectric oscillator according to an embodiment of the present invention. 1A, 1B, and 1C are diagrams showing a process of applying a resin dropwise to a piezoelectric oscillator of a comparative example. 1A and 1B are diagrams showing how resin flows under a semiconductor element in a piezoelectric oscillator of a comparative example. 13 is another example of a notch in a semiconductor element in a piezoelectric oscillator according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a piezoelectric oscillator according to the present invention will be described with reference to the drawings.
It should be noted that each of the drawings used in the description is merely a schematic illustration to the extent that the present invention can be understood. In addition, in each of the drawings used in the description, similar components are indicated by the same numbers, and their explanation may be omitted. Furthermore, the shapes, materials, etc. described in the following description are merely preferred examples within the scope of the present invention. Therefore, the present invention is not limited to the following embodiments.

Figure 1 is a diagram illustrating a piezoelectric oscillator 10 according to an embodiment of the present invention. Figure 1(A) is a perspective view of the semiconductor chamber 12 of the piezoelectric oscillator 10 as viewed from above. Figure 1(B) is a top view of the piezoelectric oscillator 10 as viewed from the semiconductor element 40 side. Figure 1(C) is a cross-sectional view taken along line A-A in Figure 1(B).

The piezoelectric oscillator 10 includes a vibrator chamber 11 , a semiconductor chamber 12 , a package 20 , a piezoelectric vibrator 30 , a semiconductor element 40 , a resin 50 , and a cover member 60 .
The package 20 has a structure in which the vibrator chamber 11 and the semiconductor chamber 12 are joined back to back. Specifically, the package 20 in this embodiment has a three-layer laminate structure including a frame-shaped first layer 20x constituting the recess 11a that houses the piezoelectric vibrator 30, a second layer 20y that serves as a common bottom for the vibrator chamber 11 and the semiconductor chamber 12, and a frame-shaped third layer 20z that constitutes the recess 12a that houses the semiconductor element 40.

Therefore, the transducer chamber 11 has a wall surrounding the recess 11a formed by the first layer 20x, a bottom 11aa formed by the second layer 20y, and a connection pad 11b for mounting the piezoelectric transducer 30 on the transducer chamber bottom 11aa.
The semiconductor chamber 12 has a wall surrounding the recess 12a formed by the third layer 20z, a bottom 12aa formed by the second layer 20y, and connection pads 12b for mounting a semiconductor element 40 on the semiconductor chamber bottom 12aa.
External connection terminals 20w for connecting to an external device are provided at the four corners of the third layer 20z of the package 20. The package 20 can be formed of, for example, a ceramic package.

The piezoelectric vibrator 30 is rectangular in plan view and has excitation electrodes on the front and back surfaces, and an extraction electrode (not shown) that is extended from each excitation electrode to one short side of the piezoelectric vibrator 30. The piezoelectric vibrator 30 is connected and fixed to the connection pad 11b of the vibrator chamber 11 at the position of the extraction electrode by conductive adhesive 11c.

The semiconductor element 40 has a rectangular shape in a plan view, and is provided with a spherical bump 40b on a portion of the semiconductor chamber bottom 12aa that faces the connection pad 12b. The semiconductor element 40 is bonded to the bottom 12aa of the semiconductor chamber 12 by, for example, flip chip bonding, via the connection pad 12b and the bump 40b. The semiconductor element 40 also has a notch 40a on the surface opposite to the surface provided with the bump 40b. The notch 40a is an example in which it is provided so as to span two sides of the semiconductor element, and in the example of FIG. 1, the notch 40a is provided so as to span two parallel long sides of the semiconductor element. The notch may also be provided so as to span two parallel short sides. The depth and width of the notches 40a are set so that a resin (described later) dripped onto the surface of the semiconductor element 40 where the notches 40a are formed during manufacturing can easily flow along the notches 40a from the edge of the semiconductor element 40 to the back surface side of the semiconductor element 40, and so as not to impair the strength of the semiconductor element 40. The notches 40a can be easily formed by making the depth of the notches of a dicing saw shallow and forming them in the semiconductor element 40 when dividing the semiconductor element 40 from the wafer by dicing.
In the embodiment shown in FIG. 1C, the cross section perpendicular to the notch 40a is U-shaped, but the notch 40a may be V-shaped or C-shaped.

The resin 50 is made of a thermosetting resin material such as epoxy resin, etc. After being dropped, the resin 50 is hardened by a heat treatment process.
The cover member 60 hermetically seals the transducer chamber 11, has a rectangular shape in a plan view, and is made of, for example, metal. This hermetically sealing structure can be any structure depending on the sealing method. For example, after creating an appropriate vacuum or inert gas atmosphere inside the transducer chamber 11, a seal ring (not shown) provided on the first layer 20x and the cover member 60 are joined by seam welding to seal the transducer chamber 11.

Next, in order to deepen understanding of the present invention, a process of applying resin 50 between the bottom 12aa of the semiconductor chamber 12 and the back surface of the semiconductor element 40 will be described with reference to Figures 2 and 3. In order to describe the process of applying resin 50, the semiconductor chamber 12 is depicted as being the upper surface in Figures 2 and thereafter.
2(A) is a diagram before resin 50 is dripped onto semiconductor element 40 of piezoelectric oscillator 10, FIG. 2(B) is a diagram after resin 50 has been dripped onto semiconductor element 40 of piezoelectric oscillator 10, FIG. 2(C) is a top view after resin 50 has been dripped onto semiconductor element 40 of piezoelectric oscillator 10, FIG. 3(A) is a diagram of resin 50 in the middle of flowing under semiconductor element 40 along the groove of notch 40a of semiconductor element 40 of piezoelectric oscillator 10, and FIG. 3(B) is a diagram of resin 50 having flowed all the way to fill the space under semiconductor element 40 of piezoelectric oscillator 10.

Resin 50 is applied dropwise to the center of the semiconductor element 40 by a resin application nozzle 51 (FIG. 2C). The resin application nozzle 51 may be a dispenser. The resin 50 immediately after application has a flared shape when viewed from the cross section, but due to the presence of the notch 40a in the semiconductor element 40, the resin 50 flows down into the groove of the notch 40a and flows along the groove to the back surface of the semiconductor element 40 (FIG. 3B). It is expected that the resin 50 will flow down the groove to the semiconductor chamber bottom 12aa and fill the space between the back surface of the semiconductor element 40, i.e., the surface having the bumps 40b, and the semiconductor chamber bottom 12aa with resin 50. However, due to the effect of the surface tension of the resin 50, it is assumed that not all of the dripped resin 50 will flow down to the bottom of the semiconductor element 40, and a small amount will remain on the semiconductor element 40.

By filling the required amount of resin between the semiconductor element 40 and the semiconductor chamber bottom 12aa, the connection pads 12b and bumps 40b can be protected by the resin 50, and frequency deviations caused by solder flux can be prevented when the piezoelectric oscillator 10 is soldered onto another electronic device. In addition, the bond between the semiconductor element 40 and the semiconductor chamber bottom 12aa is strengthened, making it possible to withstand external vibrations and shocks. As this invention is not an invention that incorporates improvements to the package, it will be able to accommodate future piezoelectric oscillators that are even smaller in size.

The process of applying resin 50 between the bottom 12aa of the semiconductor chamber 12 and the back surface of the semiconductor element 40 in the comparative example will be described with reference to Figures 4 and 5. Figure 4(A) is a diagram before the resin 50 is dripped onto the semiconductor element 41 of the piezoelectric oscillator 10, Figure 4(B) is a diagram after the resin 50 has been dripped onto the semiconductor element 41 of the piezoelectric oscillator 10, Figure 4(C) is a top view after the resin 50 has been dripped onto the semiconductor element 41 of the piezoelectric oscillator 10, Figure 5(A) is a diagram of the resin 50 flowing from above the semiconductor element 41 of the piezoelectric oscillator 10 to below the semiconductor element 41, and Figure 5(B) is a diagram of the resin 50 having flowed completely below the semiconductor element 41 of the piezoelectric oscillator 10.

Resin 50 is applied dropwise to the center of the semiconductor element 41 by a resin application nozzle 51 (Figure 4(C)). Immediately after application, the resin 50 has a flared shape when viewed in cross section, but it spreads out radially from the center of the semiconductor element 41. However, because the semiconductor element 41 does not have a notch 40a and because the resin 50 has surface tension, only a small amount of resin 50 can flow to the back surface of the semiconductor element 41, and most of the applied resin 50 remains on the semiconductor element 41.

In the above embodiment, an example is shown in which the linear slit 40a is provided on one of the two parallel sides, but the method of providing the slit 40a is not limited to this.
FIG. 6 shows another example of the notch 40 a of the semiconductor element 40 .
FIG. 6(A) is a diagram of one notch extending over two parallel sides of a rectangular semiconductor element 40, FIG. 6(B) is a diagram of two notches extending over two parallel sides of a rectangular semiconductor element 40, the two notches forming a cross shape in a planar view, FIG. 6(C) is a diagram of notches extending over two diagonal corners of the four corners of a rectangular semiconductor element 40, and FIG. 6(D) is a diagram of multiple notches extending over two adjacent sides of a rectangular semiconductor element 40.
In the above embodiment, the semiconductor element has a rectangular shape in a plan view. However, the semiconductor element may have a square shape in a plan view.

10: Piezoelectric oscillator 11: Transducer chamber 11a: Transducer chamber recess 11aa: Transducer chamber bottom 11b: Transducer chamber connection pad 11c: Conductive adhesive 12: Semiconductor chamber 12a: Semiconductor chamber recess 12aa: Semiconductor chamber bottom 12b: Semiconductor chamber connection pad 20: Package 20x: First layer of package 20y: Second layer of package 20z: Third layer of package 20w: External connection terminal 30: Piezoelectric transducer 40: Semiconductor element of the present invention 40a: Semiconductor element notch 40b: Bump 41: Semiconductor element of comparative example 50: Resin 51 Resin application nozzle 60: Lid member

Claims (4)

A piezoelectric oscillator comprising: a package in which a transducer chamber having a recess for accommodating a piezoelectric transducer and a semiconductor chamber having a recess for accommodating a semiconductor element are joined back to back; the piezoelectric transducer accommodated in the transducer chamber; the semiconductor element accommodated in the semiconductor chamber; resin filled between the bottom of the semiconductor chamber and the semiconductor element; and a lid member for sealing the transducer chamber,
The semiconductor element has a rectangular shape in a plan view,
the semiconductor element has a notch on a surface opposite to a surface bonded to the semiconductor chamber;
the notch is provided so as to extend over two sides of the semiconductor element;
A piezoelectric oscillator comprising: The piezoelectric oscillator according to claim 1, characterized in that the notch is one or more notches that span two sides of the semiconductor element. The piezoelectric oscillator according to claim 1 or 2, characterized in that the notch is a notch that extends along two parallel or adjacent sides of the semiconductor element. The piezoelectric oscillator according to claim 1, characterized in that the notch is cross-shaped in a plan view.

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