JP6407102B2 - Elastic wave device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an acoustic wave device and a manufacturing method thereof.

  In order to reduce the size and height of an acoustic wave device, a technique of flip chip mounting an acoustic wave chip on a package substrate using bumps is known. For example, a technique is known in which an elastic wave chip is flip-chip mounted on a package substrate with two bumps stacked one above the other (see, for example, Patent Document 1). In addition, a technique for bonding a bump to a concave portion of a metal pattern is known (see, for example, Patent Documents 2 to 5).

JP 2004-135093 A JP 2006-66775 A JP 2010-252051 A JP 2008-277393 A JP 2003-258017 A

  In order to reduce the size of the acoustic wave chip that is flip-chip mounted on the package substrate, it is desirable to reduce the area of the chip-side pad that is formed on the acoustic wave chip and to which the bump is connected. However, if the area of the chip-side pad is reduced, the bumps are also reduced, and the connection strength of the bumps is reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an acoustic wave device capable of suppressing a decrease in the connection strength of bumps while reducing the size of an acoustic wave chip and a method for manufacturing the same. To do.

The present invention provides a package substrate provided with a substrate-side pad, a chip-side pad, flip-chip mounted on the package substrate, and having an air gap between the package substrate and the substrate side A bump connected to the chip-side pad and exposed to the air gap, the bump being bonded to the substrate-side pad, the bump being bonded to the chip-side pad, and the first bump It is seen containing a small second bumps in the width direction than the bumps, and the second bumps, by bonding to the recessed portion not around the recess formed on the first bump the indentation, the first The elastic wave device is characterized by being bonded to one bump .

  In the above configuration, the first bump may be larger in the height direction than the second bump.

  In the above configuration, the area of the chip-side pad may be smaller than that of the substrate-side pad.

  The said structure WHEREIN: The said 1st bump and the said 2nd bump can be set as the structure which is comparable hardness.

  In the above configuration, the first bump and the second bump may be made of gold having a purity of 99.99% by weight or more.

  In the above configuration, the acoustic wave chip includes solder provided around the acoustic wave chip, and a flat metal lid provided on the solder from the acoustic wave chip. It can be set as the structure sealed by the sealing part containing.

In the above configuration, a plurality of the recesses are formed in the first bump, the plurality of recesses are formed independently without communicating with each other, and the second bump is formed in the first bump. Further, by joining to the plurality of dents and a non-dented portion around the plurality of dents, the first bump can be joined.

  In the above configuration, the first bump and the second bump may be stud bumps.

The present invention includes a step of forming a first bump having a recess on a substrate-side pad provided on a package substrate, and a width direction from the first bump on the chip-side pad provided on an acoustic wave chip. A step of forming a small second bump, and the first bump and the second bump are bonded together to expose the first bump and the second bump between the package substrate and the acoustic wave chip. as There is formed, and a step of flip-chip mounting the elastic wave chip to the package substrate, wherein the step of flip-chip mounting, the second bump is recessed the said recess and of said first bump The second bump is bonded to the first bump so as to be bonded to a non-recessed portion around the chip, thereby flipping the acoustic wave chip on the package substrate. A method for manufacturing the acoustic wave device, characterized by instrumentation.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the connection strength of a bump can be suppressed, reducing an elastic wave chip | tip.

FIG. 1A is a cross-sectional view illustrating the acoustic wave device according to the first embodiment, and FIG. 1B is an enlarged cross-sectional view of the bump connection portion of FIG. FIG. 2A to FIG. 2E are cross-sectional views (part 1) illustrating the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 3A to FIG. 3C are cross-sectional views (part 2) illustrating the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 4A to FIG. 4C are cross-sectional views (part 3) illustrating the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 5A is a cross-sectional view showing an acoustic wave device according to Comparative Example 1, and FIG. 5B is an enlarged cross-sectional view of the bump connection portion of FIG. 6A to 6C are cross-sectional views illustrating a method for manufacturing an acoustic wave device according to Comparative Example 1. FIG. FIG. 7A to FIG. 7D are cross-sectional views illustrating the method for manufacturing the acoustic wave device according to the second embodiment. FIG. 8A is a cross-sectional view illustrating the acoustic wave device according to the third embodiment, and FIG. 8B is an enlarged cross-sectional view of the bump connection portion of FIG. FIG. 9A to FIG. 9D are cross-sectional views illustrating the method for manufacturing the acoustic wave device according to the third embodiment. FIG. 10 is a plan view for explaining a recess formed in the first bump. FIG. 11A is a cross-sectional view showing an acoustic wave device according to Modification 1 of Embodiment 3, and FIG. 11B is an enlarged cross-sectional view of the bump connection portion of FIG. FIG. 12A to FIG. 12D are cross-sectional views illustrating a method for manufacturing an acoustic wave device according to the first modification of the third embodiment. FIG. 13 is a plan view for explaining a recess formed in the first bump. FIG. 14A and FIG. 14B are plan views for explaining another example of the recess formed in the first bump.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1A is a cross-sectional view illustrating the acoustic wave device according to the first embodiment, and FIG. 1B is an enlarged cross-sectional view of the bump connection portion of FIG. As shown in FIG. 1A, the acoustic wave device according to the first embodiment includes a package substrate 10 and an acoustic wave chip 20. Substrate side pads 12 are provided on the upper surface of the package substrate 10. A chip-side pad 22 is provided on the main surface of the acoustic wave chip 20. The acoustic wave chip 20 is flip-chip mounted on the flat upper surface of the package substrate 10 by connecting the substrate side pads 12 and the chip side pads 22 with bumps 30. The package substrate 10 is a ceramic made of, for example, LTCC (Low Temperature Co-fired Ceramics) or HTCC (High Temperature Co-fired Ceramics), but an insulator other than ceramic may be used. The acoustic wave chip 20 is a surface acoustic wave chip including, for example, a piezoelectric substrate 24 and an IDT (Interdigital transducer) 26 provided on the main surface of the piezoelectric substrate 24, but an acoustic wave chip other than the surface acoustic wave chip (for example, a piezoelectric wave) In the case of a thin film resonator chip or the like. For the piezoelectric substrate 24, for example, a piezoelectric material such as lithium tantalate (LT) or lithium niobate (LN) can be used. For example, a metal such as copper (Cu) or aluminum (Al) can be used for the IDT 26.

  As shown in FIG. 1B, the bump 30 includes a first bump 32 and a second bump 34 having different sizes. The first bump 32 is bonded between the substrate-side pad 12 and the second bump 34, and is wider than the second bump 34 (in a direction parallel to the upper surface of the package substrate 10) and in the height direction (package substrate). 10 in a direction perpendicular to the upper surface of the surface 10. The second bump 34 is bonded between the chip-side pad 22 and the first bump 32, and is smaller than the first bump 32 in the width direction and the height direction. That is, the second bump 34 has a smaller width in the same direction than the first bump 32. The first bump 32 and the second bump 34 are bonded to the pad in a circular shape, for example, but may be bonded in other shapes such as an elliptical shape. The diameter (size in the width direction) of the bump 30 is, for example, about 75 μm, and the height (size in the height direction) is, for example, about 25 μm. Both the first bump 32 and the second bump 34 are, for example, gold (Au) stud bumps, but may be other metal stud bumps such as copper (Cu) stud bumps and aluminum (Al) stud bumps.

  It is preferable that the first bump 32 and the second bump 34 have the same hardness. For example, when gold bumps are used, it is preferable that the first bumps 32 and the second bumps 34 have a gold purity of 99.99% by weight or more. With such a configuration, it is possible to avoid stress concentration on the first bump 32 that is easily affected by stress in a high-temperature reliability test or the like, and by reducing local distortion, Breakage between the second bumps 34 can be suppressed.

  As shown in FIG. 1A, a gap 50 is formed between the upper surface of the package substrate 10 and the acoustic wave chip 20. As a result, the IDT 26 of the acoustic wave chip 20 is suppressed from being exposed to the gap 50 and hindering vibration. Further, the bump 30 is also exposed in the gap 50. That is, the bump 30 is surrounded by the gap 50.

  The package substrate 10 is a multilayer wiring substrate having internal wirings 14 provided therein. By the internal wiring 14, the board-side pad 12 provided on the upper surface of the package substrate 10 and the foot pad 16 provided on the lower surface are electrically connected. Since the bump 30 is connected to the substrate side pad 12 and the chip side pad 22, the acoustic wave chip 20 is electrically connected to the foot pad 16. The substrate side pad 12, the chip side pad 22, the internal wiring 14 and the foot pad 16 are made of, for example, gold (Au), but may be made of other metals.

  A metal pattern 18 is provided on the upper surface of the package substrate 10 and outside the acoustic wave chip 20. The metal pattern 18 is provided so as to surround the acoustic wave chip 20. For the metal pattern 18, for example, a metal such as gold (Au) can be used. Solder 42 surrounding the acoustic wave chip 20 is provided so as to be bonded to the upper surface of the metal pattern 18. A metal lid 44 made of, for example, Kovar having a flat shape extending from the acoustic wave chip 20 to the solder 42 is provided. The metal lid 44 is not limited to Kovar, and a metal having a melting point higher than that of solder can be used. The elastic wave chip 20 is sealed by a sealing portion 40 including a solder 42 and a metal lid 44. A protective film 46 made of a metal such as a nickel (Ni) plating film is provided so as to cover the sealing portion 40.

  Next, a method for manufacturing the acoustic wave device according to the first embodiment will be described. FIG. 2A to FIG. 4C are cross-sectional views illustrating the method for manufacturing the acoustic wave device according to the first embodiment. 2 (a) to 4 (c) show a manufacturing method using a multi-chamfer process. As shown in FIG. 2A, a package substrate 10 on which substrate-side pads 12, internal wirings 14, foot pads 16, and metal patterns 18 are formed is prepared.

  As shown in FIG. 2B, the first bump 32 is formed on the upper surface of the substrate-side pad 12 by a stud bump method. The diameter of the first bump 32 is, for example, about 75 μm, and the height is, for example, about 32 μm. Note that the first bump 32 may be formed by removing the wire portion after wire bonding.

  As shown in FIG. 2C, the IDT 26 and the chip-side pad 22 are formed on the main surface of the piezoelectric substrate 24. The IDT 26 and the chip-side pad 22 can be formed by a generally used method.

  As shown in FIG. 2D, second bumps 34 smaller than the first bumps 32 in the width direction and the height direction are formed on the upper surface of the chip-side pad 22 by the stud bump method. The diameter of the second bump 34 is about 40 μm, for example, and the height is about 18 μm, for example.

  As shown in FIG. 2E, the piezoelectric substrate 24 is cut by, for example, a dicing method and separated into a plurality of acoustic wave chips 20.

  As shown in FIG. 3A, the first bump 32 formed on the substrate side pad 12 and the second bump 34 formed on the chip side pad 22 are bonded. Thus, the acoustic wave chip 20 is flip-chip mounted on the flat upper surface of the package substrate 10 by the bumps 30 including the first bumps 32 and the second bumps 34 smaller than the first bumps 32. A gap 50 is formed between the upper surface of the package substrate 10 and the acoustic wave chip 20.

  As shown in FIG. 3B, the laminate including the solder 42 and the metal lid 44 is disposed on the acoustic wave chip 20 so that the solder 42 is on the acoustic wave chip 20 side.

  As shown in FIG. 3C, the laminated body is heated to bring the solder 42 into a molten state, and in this state, the metal lid 44 is pressed to the elastic wave chip 20 side. As a result, the solder 42 is filled in the gaps between the plurality of acoustic wave chips 20. The solder 42 wets and spreads on the metal pattern 18 formed on the package substrate 10, solidifies, surrounds the periphery of the acoustic wave chip 20, and is bonded to the metal pattern 18 and the metal lid 44. The metal lid 44 is formed to extend from the acoustic wave chip 20 to the solder 42. For example, the metal lid 44 is in contact with the acoustic wave chip 20, but the solder 42 may remain between the metal lid 44 and the acoustic wave chip 20. Thereby, the acoustic wave chip 20 is sealed with the gap 50 maintained by the sealing portion 40 including the solder 42 and the metal lid 44.

  As shown in FIG. 4A, a resist film 52 that protects the foot pad 16 provided on the lower surface of the package substrate 10 is formed. Thereafter, the sealing portion 40, the package substrate 10, and the resist film 52 are cut by a dicing method using a dicing blade 54 between the plurality of acoustic wave chips 20. As a result, as shown in FIG. 4B, the device is divided into a plurality of devices 60.

  As shown in FIG. 4C, barrel plating is performed on the plurality of devices 60 to form a protective film 46 that covers the sealing portion 40. Thereafter, by removing the resist film 52, the acoustic wave device of Example 1 can be formed.

  Here, in describing the effect of the elastic wave device of Example 1, the elastic wave device of the comparative example will be described. FIG. 5A is a cross-sectional view showing an acoustic wave device according to Comparative Example 1, and FIG. 5B is an enlarged cross-sectional view of the bump connection portion of FIG. As shown in FIGS. 5A and 5B, the elastic wave device of Comparative Example 1 has two bumps 130 that are flip-chip mounted on the flat upper surface of the package substrate 10 in two sizes. The elastic wave device is different from the elastic wave device of the first embodiment in that it is not configured by bumps. The diameter of the bump 130 is about 110 μm, for example, and the height is about 8 μm, for example. The other configuration of the acoustic wave device of Comparative Example 1 is the same as that of FIG. 1A and FIG.

  6A to 6C are cross-sectional views illustrating a method for manufacturing an acoustic wave device according to Comparative Example 1. FIG. As shown in FIG. 6A, the IDT 26 and the chip-side pad 22 are formed on the main surface of the piezoelectric substrate 24. A bump 130 is formed on the upper surface of the chip-side pad 22 by a stud bump method. The diameter of the bump 130 is about 75 μm, for example, and the height is about 32 μm, for example.

  As shown in FIG. 6B, the piezoelectric substrate 24 is cut and separated into a plurality of acoustic wave chips 20. Thereafter, as shown in FIG. 6C, after preparing the package substrate 10 on which the substrate-side pad 12, the internal wiring 14, the foot pad 16, and the metal pattern 18 are formed, the bump 130 is bonded to the substrate-side pad 12. Then, the acoustic wave chip 20 is flip-chip mounted on the flat upper surface of the package substrate 10.

  After FIG. 6C, the elastic wave device of Comparative Example 1 can be formed by performing the same steps as those in FIGS. 3B to 4C of Example 1.

  In the acoustic wave device of Comparative Example 1, bumps 130 are formed on the chip side pads 22 as shown in FIG. 6A, and the bumps 130 are bonded to the substrate side pads 12 as shown in FIG. 6C. Thus, the acoustic wave chip 20 is flip-chip mounted on the package substrate 10. In this case, if the area of the chip-side pad 22 is reduced in order to reduce the size of the acoustic wave chip 20, the bump 130 is also reduced, and as a result, the height of the bump 130 after flip-chip mounting is reduced. When a stress is applied to the bump 130 due to a thermal history of the manufacturing process (for example, heat when the acoustic wave chip 20 is solder-sealed) or the like, the stress (stress) is absorbed when the height of the bump 130 is low. It is difficult to peel off the bumps 130 and the like. Thus, in the acoustic wave device of Comparative Example 1, it is difficult to make the bumps 130 small, so it is difficult to make the chip-side pads 22 small, and as a result, downsizing is difficult.

  On the other hand, in the acoustic wave device of Example 1, as shown in FIG. 1B, the bump 30 that connects the substrate side pad 12 and the chip side pad 22 includes the first bump 32 bonded to the substrate side pad 12. The second bump 34 is bonded to the chip side pad 22 and is smaller in the width direction than the first bump 32. As described above, by reducing the width direction of the second bump 34 bonded to the chip-side pad 22, the area of the chip-side pad 22 can be reduced, and the acoustic wave chip 20 can be downsized. In Comparative Example 1, the size of the chip-side pad 22 is about 90 μm square, whereas in Example 1, it can be about 50 μm square. Further, by increasing the width direction of the first bump 32 bonded to the substrate-side pad 12, the height of the bump 30 after flip chip mounting can be increased for the reasons described later. A decrease in connection strength can be suppressed.

  Further, as shown in FIG. 1B, when the first bump 32 is larger in the height direction than the second bump 34, the bump 30 after flip chip mounting becomes higher, and the connection strength of the bump 30 is reduced. Can be effectively suppressed.

  In the acoustic wave device according to the first embodiment, the first bump 32 is formed on the substrate-side pad 12 provided on the package substrate 10 as illustrated in FIG. As shown in FIG. 2E, a second bump 34 smaller than the first bump 32 in the width direction is formed on the chip-side pad 22 provided on the acoustic wave chip 20. Then, as shown in FIG. 3A, the first bump 32 and the second bump 34 are joined, and the acoustic wave chip 20 is flip-chip mounted on the package substrate 10. According to this manufacturing method, the chip-side pad 22 can be reduced by reducing the width direction of the second bump 34, and the bump 30 after flip-chip mounting can be increased by increasing the width direction of the first bump 32. Further, it is possible to suppress the decrease in the connection strength of the bumps 30 while downsizing the acoustic wave chip 20.

  As shown in FIG. 3A, when the acoustic wave chip 20 is flip-chip mounted, the second bumps 34 that are small in the width direction are joined to the first bumps 32 that are large in the width direction. The alignment margin of the second bumps 34 with respect to the first bumps 32 is larger than the case where the two are bonded. That is, even when the second bump 34 is joined with being slightly shifted from the center of the first bump 32, it is possible to suppress an increase in the width direction of the bump 30 including the first bump 32 and the second bump 34. Further, when the second bumps 34 that are small in the width direction are joined to the first bumps 32 that are large in the width direction, the second bumps 34 that are small in the width direction are preferentially crushed, and the first bumps 32 that are large in the width direction are not crushed. For this reason, the width direction of the bumps 30 can be prevented from increasing. In this way, by bonding the first bump 32 that is large in the width direction and the second bump 34 that is small in the width direction, for example, compared to the case where the bumps having the same size are bonded to each other, the bump 30 after flip-chip mounting is used. It is possible to easily control the size in the width direction.

  In addition, when the first bumps 32 that are large in the width direction and the second bumps 34 that are small in the width direction are joined, the first bumps 32 that are large in the width direction are not crushed so much. Compared to the above, the bump 30 after flip-chip mounting can be made higher. Therefore, it is possible to effectively suppress a decrease in the connection strength of the bump 30.

  From the viewpoint of downsizing the acoustic wave chip 20, it is preferable that the area of the chip side pad 22 is smaller than that of the substrate side pad 12 as shown in FIG.

  As shown in FIG. 1A, the elastic wave chip 20 includes a solder 42 surrounding the elastic wave chip 20, and a flat metal lid 44 provided to extend from the elastic wave chip 20 onto the solder 42. In other words, the bumps 30 are likely to be peeled off due to heat stress during solder sealing. Therefore, in such a case, it is preferable to form the bump 30 with the first bump 32 and the second bump 34 in order to reduce the size of the acoustic wave chip 20 and suppress the decrease in the connection strength of the bump 30.

  Further, as shown in FIG. 1A, when the bumps 30 are exposed in the gap 50, the bumps 30 are likely to be peeled off due to stress (stress) due to the thermal history of the manufacturing process. Therefore, in such a case, it is preferable to form the bump 30 with the first bump 32 and the second bump 34 in order to reduce the size of the acoustic wave chip 20 and suppress the decrease in the connection strength of the bump 30.

  Since the elastic wave device according to the second embodiment is the same as the elastic wave device according to the first embodiment, except that the size of the bump 30 is different from that of the first embodiment, FIG. 1A and FIG. The illustration is omitted. The diameter of the bump 30 in the acoustic wave device of Example 2 is, for example, about 60 μm, and the height is, for example, about 10 μm.

  FIG. 7A to FIG. 7C are cross-sectional views illustrating the method for manufacturing the acoustic wave device according to the second embodiment. As shown in FIG. 7A, the IDT 26 and the chip-side pad 22 are formed on the main surface of the piezoelectric substrate 24. A second bump 34 is formed on the upper surface of the chip-side pad 22 by a stud bump method. The diameter of the second bump 34 is, for example, about 38 μm, and the height is, for example, about 17 μm.

  As shown in FIG. 7B, the first bump 32 larger than the second bump 34 in the width direction and the height direction is formed on the second bump 34 by the stud bump method. The diameter of the first bump 32 is, for example, about 40 μm, and the height is, for example, about 18 μm. Thereby, the bump 30 including the first bump 32 and the second bump 34 is formed.

  As shown in FIG. 7C, the piezoelectric substrate 24 is cut and separated into a plurality of acoustic wave chips 20. Thereafter, as shown in FIG. 7D, after preparing the package substrate 10 on which the substrate-side pad 12, the internal wiring 14, the foot pad 16, and the metal pattern 18 are formed, the first bump 32 is used as the substrate-side pad 12. Then, the acoustic wave chip 20 is flip-chip mounted on the flat upper surface of the package substrate 10.

  After FIG. 7D, the elastic wave device of Example 2 can be formed by performing the same steps as those in FIGS. 3B to 4C of Example 1.

  As shown in FIG. 7C, the acoustic wave device of Example 2 has a first bump that is larger in the width direction than the second bump 34 and the second bump 34 on the chip-side pad 22 provided in the acoustic wave chip 20. A bump 30 is formed by stacking the bumps 32 in this order. Then, as shown in FIG. 7D, bumps 30 are bonded to the substrate-side pads 12 provided on the package substrate 10, and the acoustic wave chip 20 is flip-chip mounted on the package substrate 10. Also by this manufacturing method, the chip-side pad 22 can be reduced by reducing the width direction of the second bump 34, and the bump 30 after flip-chip mounting can be increased by increasing the width direction of the first bump 32. While the acoustic wave chip 20 is downsized, a decrease in the connection strength of the bumps 30 can be suppressed.

  As shown in FIG. 7C, when the second bump 34 that is small in the width direction and the first bump 32 that is large in the width direction are stacked, the bumps of the same size are stacked. In comparison, the collapse of the first bump 32 after flip chip mounting can be suppressed, and the bump 30 can be easily raised.

  In the first and second embodiments, the first bump 32 and the second bump 34 may be bumps other than stud bumps (for example, plated bumps). Further, the bump 30 is not limited to the two-stage structure of the first bump 32 and the second bump 34, and may have a structure of three or more stages.

  FIG. 8A is a cross-sectional view illustrating the acoustic wave device according to the third embodiment, and FIG. 8B is an enlarged cross-sectional view of the bump connection portion of FIG. As shown in FIGS. 8A and 8B, the acoustic wave device according to the third embodiment is configured so that the substrate-side pad 12 and the first bump 32 cover the recess formed on the upper surface of the package substrate 10. They are formed in this order on the upper surface of the substrate 10. For this reason, a recess is formed on the upper surface of the first bump 32. The dent formed in the first bump 32 is provided without penetrating the first bump 32 and will be described in detail with reference to FIG. 10 described later. For example, a circular shape is formed at the center of the upper surface of the first bump 32. Is formed. The second bump 34 is bonded to the first bump 32 by at least bonding to the recess formed in the first bump 32. For example, the second bump 34 is joined to a recess formed in the first bump 32 and a non-recessed portion around the recess. The first bump 32 is, for example, a gold (Au) plating bump. The second bump 34 is, for example, a gold (Au) stud bump. Other configurations are the same as those of the first embodiment shown in FIGS. 1A and 1B, and the description thereof is omitted.

  Next, a method for manufacturing an acoustic wave device according to Example 3 will be described. FIG. 9A to FIG. 9D are cross-sectional views illustrating the method for manufacturing the acoustic wave device according to the third embodiment. 9A to 9D show a manufacturing method using a multi-chamfering process as in the first embodiment.

  As shown in FIG. 9A, a recess 70 is formed on the upper surface of the package substrate 10. The recess 70 can be formed by, for example, drilling when the package substrate 10 is a ceramic substrate, and can be formed by digging with a laser, for example, when the package substrate 10 is a resin substrate. it can. The depth of the recess 70 is, for example, about 5 μm to 10 μm.

  As shown in FIG. 9B, the substrate side pad 12, the internal wiring 14, the foot pad 16, and the metal pattern 18 are formed on the package substrate 10. The substrate-side pad 12 is formed so as to cover the recess 70 of the package substrate 10. Accordingly, a recess corresponding to the recess 70 of the package substrate 10 is also formed on the upper surface of the substrate-side pad 12. Thereafter, the first bump 32 is formed on the upper surface of the substrate-side pad 12 using a plating method so as to cover the recess formed on the upper surface of the substrate-side pad 12. The diameter of the first bump 32 is, for example, about 20 to 80 μm, and the height is, for example, about 5 μm to 10 μm. A recess 72 is also formed on the upper surface of the first bump 32. As shown in FIG. 10, the recess 72 is formed in a circular shape at the center of the upper surface of the first bump 32, for example. The depth of the dent 72 is, for example, about 5 to 10 μm.

  As shown in FIG. 9C, the acoustic wave chip 20 in which the IDT 26, the chip-side pad 22, and the second bump 34 are formed on the main surface of the piezoelectric substrate 24 is formed. The elastic wave chip 20 can be formed by the steps of FIGS. 2C to 2E of the first embodiment. The diameter of the second bump 34 is, for example, about 20 to 60 μm, and the height is, for example, 20 μm to 30 μm.

  As shown in FIG. 9D, the second bump 34 is joined to the first bump 32 by thermocompression bonding so that the second bump 34 is at least joined to the recess 72 formed in the first bump 32. Thereafter, the same steps as those in FIGS. 3B to 4C of Example 1 are performed. Thereby, the elastic wave device of Example 3 can be formed.

  According to the third embodiment, the second bump 34 is bonded to the first bump 32 by at least bonding to the recess 72 formed in the first bump 32. Thereby, it is possible to suppress the second bump 34 from sliding to the first bump 32, and as a result, it is possible to suppress the displacement of the acoustic wave chip 20 with respect to the package substrate 10. In addition, the bonding area between the first bump 32 and the second bump 34 can be increased, and a decrease in bonding strength of the bump 30 can be suppressed.

  FIG. 11A is a cross-sectional view showing an acoustic wave device according to Modification 1 of Embodiment 3, and FIG. 11B is an enlarged cross-sectional view of the bump connection portion of FIG. In the elastic wave device according to the first modification of the third embodiment, as shown in FIGS. 11A and 11B, no recess is formed on the upper surface of the package substrate 10 and the upper surface of the substrate-side pad 12. A recess is formed only on the upper surface of the first bump 32. The recess formed on the upper surface of the first bump 32 is provided, for example, so as to penetrate the first bump 32, and will be described in detail later with reference to FIG. Note that the recess formed on the upper surface of the first bump 32 may not penetrate the first bump 32. The second bump 34 is bonded to the first bump 32 by at least bonding to the recess formed in the first bump 32. For example, the second bump 34 is joined to a recess formed in the first bump 32 and a non-recessed portion around the recess. The first bump 32 is, for example, a gold (Au) plating bump. The second bump 34 is, for example, a gold (Au) stud bump. Other configurations are the same as those of the first embodiment shown in FIGS. 1A and 1B, and the description thereof is omitted.

  Next, the manufacturing method of the elastic wave device which concerns on the modification 1 of Example 3 is demonstrated. FIG. 12A to FIG. 12D are cross-sectional views illustrating a method for manufacturing an acoustic wave device according to the first modification of the third embodiment. 12 (a) to 12 (d) show a manufacturing method using a multi-chamfering process, as in the first embodiment. As shown in FIG. 12A, a package substrate 10 on which substrate-side pads 12, internal wirings 14, foot pads 16, and metal patterns 18 are formed is prepared. The substrate-side pad 12 is formed on the flat upper surface of the package substrate 10. For this reason, the upper surface of the substrate side pad 12 has a flat shape.

  As shown in FIG. 12B, the first bump 32 is formed on the upper surface of the substrate-side pad 12 by plating. At this time, the first bump 32 having the recess 72 is formed by controlling the shape of the plating resist (not shown). The dent 72 is formed, for example, in a cross shape as shown in FIG. The diameter of the first bump 32 is, for example, about 20 to 80 μm, and the height is, for example, about 5 μm to 10 μm.

  As shown in FIG. 12C, the acoustic wave chip 20 in which the IDT 26, the chip-side pad 22, and the second bump 34 are formed on the main surface of the piezoelectric substrate 24 is formed. The elastic wave chip 20 can be formed by the steps of FIGS. 2C to 2E of the first embodiment. The diameter of the second bump 34 is, for example, about 20 to 60 μm, and the height is, for example, 20 μm to 30 μm.

  As shown in FIG. 12D, the second bump 34 is joined to the first bump 32 by thermocompression bonding so that the second bump 34 is at least joined to the recess 72 formed in the first bump 32. Thereafter, the same steps as those in FIGS. 3B to 4C of Example 1 are performed. Thereby, the elastic wave device of the modification 1 of Example 3 can be formed.

  Also in the first modification of the third embodiment, as in the third embodiment, the second bump 34 is bonded to the first bump 32 by at least bonding to the recess 72 formed in the first bump 32. For this reason, it is possible to suppress the displacement of the elastic wave chip 20 due to the side slip of the second bump 34, and to suppress the decrease in the bonding strength of the bump 30.

  In the third embodiment and the first modification of the third embodiment, the recess 72 formed in the first bump 32 is not limited to a circular shape or a cross shape, but may have other shapes such as an elliptical shape or a rectangular shape. It may be the case. FIG. 14A and FIG. 14B are plan views for explaining another example of the dent 72 formed in the first bump 32. As shown in FIG. 14 (a), a recess 72 having a shape extending in three directions from the central portion of the first bump 32 may be formed. As shown in FIG. 14 (b), a plurality of recesses 72 may be formed. It may be formed. In addition, the case where the recessed part and the part which is not recessed may be reversed may be sufficient. In other words, in FIG. 14A, the first bump 32 may have a protrusion extending in three directions from the central portion, and the other portion may be a recess 72. In FIG.14 (b), the case where the dent 72 which forms a some protrusion is formed may be sufficient.

  In the third embodiment and the first modification of the third embodiment, the second bump 34 is a stud bump. However, the second bump 34 may be a plated bump. Also, solder may be formed at the tip of the second bump 34.

  In the third embodiment and the first modification of the third embodiment, the height of the first bump 32 is not limited to the case where the height is lower than that of the second bump 34, and may be higher. By making the first bump 32 low, the height of the acoustic wave device can be reduced. On the other hand, since the bumps 30 are increased by increasing the first bumps 32, a decrease in the connection strength of the bumps 30 can be suppressed.

  In the third embodiment and the first modification of the third embodiment, the second bump 34 is bonded only to the recess 72 formed in the first bump 32 and is not bonded to the non-recessed portion around the recess 72. It may be the case.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 10 Package board | substrate 12 Board | substrate side pad 14 Internal wiring 16 Foot pad 18 Metal pattern 20 Elastic wave chip 22 Chip side pad 24 Piezoelectric substrate 26 IDT
30 Bump 32 1st bump 34 2nd bump 40 Sealing part 42 Solder 44 Metal lid 46 Protective film 50 Gap 70, 72 Recess

Claims (9)

A package substrate provided with a substrate-side pad;
An acoustic wave chip provided with a chip-side pad, flip-chip mounted on the package substrate, and having a gap between the package substrate ;
Connecting the substrate-side pad and the chip-side pad, and a bump exposed in the gap ,
The bump includes a first bump bonded to the substrate side pads are bonded to the chip pads, seen including and a smaller second bump in a width direction than the first bump,
The elastic wave device according to claim 1, wherein the second bump is bonded to the first bump by bonding to a recess formed in the first bump and a non-recessed portion around the recess .   2. The acoustic wave device according to claim 1, wherein the first bump is larger in the height direction than the second bump.   3. The acoustic wave device according to claim 1, wherein an area of the chip side pad is smaller than that of the substrate side pad.   4. The acoustic wave device according to claim 1, wherein the first bump and the second bump have substantially the same hardness. 5.   5. The acoustic wave device according to claim 1, wherein the first bump and the second bump are made of gold having a purity of 99.99 wt% or more.   The elastic wave chip includes a solder provided so as to surround the elastic wave chip, and a flat metal lid extending from the elastic wave chip onto the solder. 6. The acoustic wave device according to claim 1, wherein the acoustic wave device is sealed by a portion. A plurality of the recesses are formed in the first bump,
The plurality of recesses are formed independently without communicating with each other,
The second bump is bonded to the first bump by bonding to the plurality of recesses formed on the first bump and a non-recessed portion around the plurality of recesses. The elastic wave device according to any one of claims 1 to 6. The acoustic wave device according to any one of claims 1 to 7 , wherein the first bump and the second bump are stud bumps. Forming a first bump having a recess on a substrate-side pad provided on the package substrate;
Forming a second bump smaller in the width direction than the first bump on a chip-side pad provided in the acoustic wave chip;
The package substrate is formed such that the first bump and the second bump are joined to form a gap in which the first bump and the second bump are exposed between the package substrate and the acoustic wave chip. And a step of flip-chip mounting the acoustic wave chip on the top,
In the flip-chip mounting step, the second bump is bonded to the first bump so that the second bump is bonded to the recess of the first bump and a non-recessed portion around the recess. The method of manufacturing an acoustic wave device , wherein the acoustic wave chip is flip-chip mounted on the package substrate .

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