Acoustic Wave Device Package

Abstract

To provide an elastic wave device package appropriately having high heat dissipation characteristics while ensuring high integration of an elastic wave device and a package substrate.SOLUTION: An elastic wave device package D includes: an acoustic wave device 1 having an electrode pattern including a comb electrode formed on one surface 1b of a piezoelectric substrate 1a; a package substrate 2 on which the acoustic wave device 1 is mounted with a gap G formed between the package substrate and the one surface 1b of the acoustic wave device 1; a resin layer 3 including a first portion 3a formed on the mounting side of the package substrate 2 and covering at least a part of the other surface 1c of the acoustic wave device 1 and a second portion 3b sealing the gap G; and a metal layer 4 formed to cover the resin layer 3. The first portion 3a of the resin layer 3 is formed so as to form an uncovered portion 3c exposing the other surface 1c of the acoustic wave device 1, and the other surface 1c of the acoustic wave device 1 facing the uncovered portion 3c is covered with the metal layer 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an improvement to an acoustic wave device package having a hollow structure with a gap sealed with a resin layer between an acoustic wave device and a package substrate. [Background technology]

[0002] Filters using surface acoustic waves (acoustic wave devices) are widely used in the transmitting and receiving circuits of mobile phones. Patent Document 1 shows an acoustic wave device package having a hollow structure with a gap sealed with a resin layer between the acoustic wave device and the package substrate.

[0003] In the structure of Patent Document 1, an acoustic wave device is mounted on a substrate and covered with a cover sheet. Patent Document 1 describes that the cover sheet can be made of plastic, metal, or resin mixed with metal particles.

[0004] However, when the cover sheet is made of a plastic sheet, since plastic has low thermal conductivity, it is difficult to dissipate the heat generated in the acoustic wave device during transmission and reception, and this often impairs the electrical characteristics (TCF characteristics) of the acoustic wave device 1. In addition, the interdigital transducer (IDT) of the acoustic wave device may be destroyed by heat accumulation.

[0005] In addition, when the cover sheet is made of a metal sheet or a resin mixed with metal particles, the difference between the thermal expansion coefficient of the acoustic wave device and that of the cover sheet becomes large, making it difficult to stabilize the adhesion between the cover sheet and the acoustic wave device or substrate, and the problem of so-called blister peeling is likely to occur. When such peeling occurs, the cover sheet is no longer in close contact with the acoustic wave device at the peeled location, so the expected heat dissipation of the cover sheet is impaired, and the electrical characteristics of the acoustic wave device are also impaired. In addition, such peeling impairs the integrity of the acoustic wave device and the package substrate, and can cause disconnection, etc. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2002-504773 Summary of the Invention [Problem to be solved by the invention]

[0007] The main problem that the present invention is intended to solve is how to provide this type of acoustic wave device package with high heat dissipation characteristics while maintaining a high degree of integrity between the acoustic wave device and the package substrate. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides an acoustic wave device package, comprising: an acoustic wave device having an electrode pattern including a comb-shaped electrode formed on one surface of a piezoelectric substrate; a package substrate on which the acoustic wave device is mounted with a gap formed between the package substrate and the one surface of the acoustic wave device; a resin layer formed on the mounting side of the package substrate and including a first portion covering at least a portion of the other surface of the acoustic wave device and a second portion sealing the gap; a metal layer formed to cover the resin layer, the first portion of the resin layer is formed to form an uncovered portion that exposes the other surface of the acoustic wave device; The other surface of the acoustic wave device facing the uncovered portion is covered with the metal layer.

[0009] In one aspect of the present invention, the first portion of the resin layer is formed in a lattice pattern.

[0012] In one embodiment of the present invention, the metal layer is made of Invar.

[0013] In one embodiment of the present invention, the metal layer contains phosphorus.

[0014] In one embodiment of the present invention, the metal layer is made of nickel.

[0015] In addition, one aspect of the present invention is that the metal layer is formed by laminating a metal film made of titanium that is in contact with the other surface of the acoustic wave device and a metal film made of copper that is formed on this metal film made of titanium.

[0016] In addition, one aspect of the present invention is that the metal layer is formed by laminating a metal film made of titanium that is in contact with the other surface of the acoustic wave device, a metal film made of copper formed on this metal film made of titanium, and a metal film made of nickel formed on this metal film made of copper. Effect of the Invention

[0017] According to the present invention, it is possible to provide an acoustic wave device package with excellent heat dissipation characteristics while ensuring high integrity between the acoustic wave device and the package substrate. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view of an acoustic wave device (first example) constituting an acoustic wave device package according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cutaway plan view showing the main part of the first example. [Diagram 3] FIG. 3 is a plan view showing the configuration of the acoustic wave device package of the first example, with metal layers omitted. [Figure 4] FIG. 4 is a plan view showing the configuration of an acoustic wave device package (second example) obtained by partially modifying the configuration of the first example, with metal layers omitted. [Diagram 5]FIG. 5 is a plan view showing the configuration of an acoustic wave device package (third example) obtained by partially modifying the configuration of the first example, with metal layers omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A typical embodiment of the present invention will be described below with reference to Fig. 1 to Fig. 5. An acoustic wave device package D according to this embodiment includes an acoustic wave device 1 (chip), a package substrate 2 (wiring substrate), a resin layer 3 (mold resin), and a metal layer 4.

[0020] (Acoustic Wave Device 1) The acoustic wave device 1 is formed by forming an electrode pattern (not shown) including an interdigital transducer (IDT) on one surface 1b of a piezoelectric substrate 1a using a metal film. That is, the acoustic wave device 1 is plate-shaped, and the one surface 1b is used as the surface on which the electrode pattern is formed.

[0021] The acoustic wave device 1 also has a surface 1c opposite to the surface (the surface 1b) on which the comb-shaped electrodes are formed, and also has an end surface 1d extending along the thickness direction.

[0022] In the illustrated example, the acoustic wave device has a rectangular plate shape having one surface 1b and the other surface 1c of the rectangle.

[0023] (Package substrate 2) The package substrate 2 is configured to mount the acoustic wave device 1 thereon with a gap G formed between the package substrate 2 and the surface 1b of the acoustic wave device 1.

[0024] The package substrate 2 is made of an insulating plate-shaped material and has a surface 2a on which the acoustic wave device 1 is mounted, a back surface 2b opposite to the surface 2a, and an end surface 2c extending along the thickness direction.

[0025] The package substrate 2 is formed to a size that allows an end face 2c of the package substrate 2 to be positioned outside an end face 1d of the acoustic wave device 1 at any position around the center of the acoustic wave device 1.

[0026] The acoustic wave device 1 is typically mounted on the surface 2a of the package substrate 2 in a state where a pad electrode (not shown) formed on the surface 1b of the acoustic wave device 1 and a pad electrode (not shown) formed on the surface 2a of the package substrate 2 are integrated via a bump 5 previously formed on the acoustic wave device 1 side. A typical example of the bump 5 is a gold stud bump formed by the first bond of wire bonding. The bump 5 and the pad electrode of the acoustic wave device 1 are fixed by a known method such as ultrasonic welding.

[0027] A gap G, which is at least the thickness of the bump 5, is formed between the surface 1b of the acoustic wave device 1 and the front surface 2a of the package substrate 2 at every location on the surface 1b of the acoustic wave device 1.

[0028] External connection terminals (not shown) are formed on the back surface 2b of the package substrate 2. The acoustic wave device 1 mounted on the package substrate 2 as described above has at least a part of its comb-shaped electrode electrically connected to the external connection terminals.

[0029] (Resin layer 3) A resin layer 3 is formed on the mounting side of the package substrate 2. The resin layer 3 includes a first portion 3a that covers at least a part of the other surface 1c of the acoustic wave device 1 and a second portion 3b that seals the gap G. The resin layer 3 forms a hollow portion 6 between the package substrate 2 and the acoustic wave device 1, surrounding the comb-shaped electrode.

[0030] The first portion 3a of the resin layer 3 is formed so as to form an uncovered portion 3c that exposes the other surface 1c of the acoustic wave device 1.

[0031] 1 to 3, the first portion 3a of the resin layer 3 is formed in a lattice pattern. In the illustrated example, the first portion 3a is provided in a frame portion 3aa that borders the other surface 1c of the acoustic wave device 1, with a plurality of first linear portions 3ab parallel to one side of the other surface 1c and a plurality of second linear portions 3ac perpendicular to the one side, thereby providing a plurality of quadrangular uncovered portions 3c.

[0032] 4, the first portion 3a of the resin layer 3 is formed so that the uncovered portions 3c are formed in a scattered manner. In the illustrated example, a plurality of circular uncovered portions 3c are formed in the first portion 3a.

[0033] 5, at least a part of the first portion 3a of the resin layer 3 is formed in a scattered manner. In the illustrated example, the first portion 3a has a shape in which a plurality of rectangular dot-shaped portions 3ad are formed within a frame portion 3aa that borders the other surface 1c of the acoustic wave device 1. Uncovered portions 3c are formed between the dot-shaped portions 3ad and between the frame portion 3aa and the dot-shaped portions 3ad.

[0034] In this embodiment, the second portion 3b of the resin layer 3 includes a vertical portion 3ba that is located between a corner 1e where the other surface 1c of the acoustic wave device 1 and the end surface 1d are in contact with each other and the surface 2a of the package substrate 2, and covers the end surface 1d of the acoustic wave device 1, and a horizontal portion 3bb that extends from a point where the vertical portion 3ba is in contact with the surface 2a of the package substrate 2 toward the end surface 2c of the package substrate 2. The horizontal portion 3bb is in close contact with the surface 2a of the package substrate 2, but does not reach the end surface 2c of the package substrate 2, and a gap is formed between a terminal 3bc of the horizontal portion 3bb and the end surface 2c of the package substrate 2.

[0035] (metal layer 4) The metal layer 4 is formed so as to cover the entire resin layer 3 and the other surface 1c of the acoustic wave device 1 facing an uncovered portion 3c described below. The metal layer 4 includes a first surface 4a formed so as to sandwich the first portion 3a of the resin layer 3 between the metal layer 4 and the other surface 1c of the acoustic wave device 1, a second surface 4b formed so as to sandwich the vertical portion 3ba of the second portion 3b of the resin layer 3 between the metal layer 4 and the end surface 1c of the acoustic wave device 1, and a third surface 4c formed so as to sandwich the horizontal portion 3bb of the second portion 3b of the resin layer 3 between the metal layer 4 and the package substrate 2. A terminal 4d of the third surface 4c reaches a corner 2d where the surface 2a and the end surface 2c of the package substrate 2 are in contact with each other, and the third surface 4c also covers a terminal 3bc of the horizontal portion 3bb of the second portion 3b of the resin layer 3.

[0036] If the package substrate 2 is made of a material such as ceramic that has no gas permeability or has low gas permeability, the metal layer 4 thus formed can maintain high gas barrier properties of the hollow portion 6.

[0037] The metal layer 4 thus formed covers the other surface 1c of the acoustic wave device 1 facing the uncovered portion 3c. That is, the metal layer 4 is in direct contact with the other surface 1c of the acoustic wave device 1 facing the uncovered portion 3c, and covers this other surface 1c.

[0038] This provides the following effects: (1) High heat dissipation: Since the metal layer 4 is in direct contact with the other surface 1c of the acoustic wave device 1, the heat generated from the acoustic wave device 1 is efficiently conducted, resulting in a structure with excellent heat dissipation characteristics. (2) Adhesion: By forming an area where the resin layer 3 contacts and an area where the metal layer 4 contacts on the other surface 1c of the acoustic wave device 1, the adhesiveness of the metal layer 4 to the acoustic wave device 1 is improved. That is, the resin layer 3 can relieve the stress caused by the difference in the thermal expansion coefficient between the piezoelectric substrate constituting the acoustic wave device 1 and the metal layer 4. As a result, the adhesiveness of the other surface 1c of the acoustic wave device 1 facing the uncovered portion 3c can be improved. 1c In this case, peeling of the metal layer 4 can be prevented as much as possible.

[0039] Such metal layer 4 can be formed by forming a thin film by physical vapor deposition (PVD) or chemical vapor deposition (CVD) and then by electrolytic plating.

[0040] The metal layer 4 can also be directly formed by electroless nickel plating. In this case, the metal layer 4 is made of nickel. When formed by electrolytic plating, a seed layer (PVD or CVD) for conducting electricity needs to be formed, which lengthens the manufacturing process, making it difficult to reduce the production cost of the acoustic wave device package D. In contrast, when electroless nickel plating is used, this seed layer is not necessary, making it possible to reduce the production cost of the acoustic wave device package D as much as possible.

[0041] Furthermore, if the electroless nickel plating contains phosphorus, the weather resistance can be improved.

[0042] Moreover, if the metal layer 4 is formed by Invar plating, the thermal expansion coefficient of the metal film can be effectively reduced.

[0043] The metal layer 4 may be formed by laminating a metal film made of titanium that is in contact with the other surface 1c of the acoustic wave device 1 and a metal film made of copper that is formed on the metal film made of titanium. In this case, the metal film made of titanium can improve the adhesion between the acoustic wave device 1 and the metal layer 4, and the metal film made of copper, which has high electrical and thermal conductivity and is formed thereon, can improve the heat dissipation properties of the metal layer 4.

[0044] Alternatively, the metal layer 4 may be formed by laminating a metal film made of titanium in contact with the other surface 1c of the acoustic wave device 1, a metal film made of copper formed on the metal film made of titanium, and a metal film made of nickel formed on the metal film made of copper. In this case, discoloration of the metal layer 4 can be prevented by covering the metal film made of copper, which is easily discolored by oxidation, with a metal film made of nickel. In this case, the metal film made of nickel may be formed by PVD or CVD, but it is preferable to form it by electrolytic nickel plating in consideration of cost and thickness.

[0045] The acoustic wave device 1 described above can typically be manufactured by the following procedure.

[0046] Step 1: The acoustic wave device 1 is flip-chip mounted on the package substrate 2. Step 2: A resin sheet is heated and pressurized in a vacuum to form a resin layer 3 on the side of the package substrate 2 obtained in step 1 on which the acoustic wave device 1 is mounted. Step 3: The resin layer 3 formed on the other surface 1c of the acoustic wave device 1 is removed in a desired shape by a laser to form an uncovered portion 3c. By removing the resin layer 3 by the laser, a gap can also be formed between the terminal 3bc of the lateral portion 3bb and the end surface 2c of the package substrate 2 in the first example shown in FIGS. 1 to 3. Step 4: Remove the cutting waste such as debris generated in step 3. Step 5: The acoustic wave device 1 package that has been subjected to step 4 is subjected to plasma cleaning in order to improve the adhesion of the electroless nickel plating. Step 6: A metal layer 4 is formed on the acoustic wave device 1 package that has been subjected to step 5 by electroless nickel plating. Step 7: Divide into individual pieces using a blade dicer or similar. Step 3 can also be performed using a blade dicer.

[0047] Of course, the present invention is not limited to the above-described embodiments, but includes all embodiments that can achieve the object of the present invention. [Explanation of symbols]

[0048] D Acoustic Wave Device Package G Gap 1. Acoustic Wave Devices 1a Piezoelectric substrate 1b one side 1c other side 1d end face 1e corner 2 Package substrate 2a surface 2b Back side 2c end face 2d corner 3 Resin layer 3a first part 3aa Frame section 3ab First linear part 3ac second linear part 3ad Dot 3b Second part 3ba Vertical part 3bb Horizontal part 3bc terminal 3c Uncoated area 4 metal layer 4a First side 4b Second surface part 4c Third side 4d Terminal 5. Bump 6 Hollow part

Claims

1. an acoustic wave device having an electrode pattern including a comb-shaped electrode formed on one surface of a piezoelectric substrate; a package substrate on which the acoustic wave device is mounted with a gap formed between the package substrate and the one surface of the acoustic wave device; a resin layer formed on the mounting side of the package substrate and including a first portion covering at least a portion of the other surface of the acoustic wave device and a second portion sealing the gap; a metal layer formed to cover the resin layer, the first portion of the resin layer is formed to form an uncovered portion that exposes the other surface of the acoustic wave device; the other surface of the acoustic wave device facing the uncovered portion is covered with the metal layer; Moreover, the first portion of the resin layer is formed in a lattice pattern to provide a plurality of rectangular uncovered portions.

2. 2. The acoustic wave device package according to claim 1, wherein the metal layer is made of Invar.

3. 2. The acoustic wave device package according to claim 1, wherein the metal layer contains phosphorus.

4. 2. The acoustic wave device package according to claim 1, wherein the metal layer is made of nickel.

5. 2. The acoustic wave device package of claim 1, wherein the metal layer is a laminate of a metal film made of titanium that is in contact with the other surface of the acoustic wave device and a metal film made of copper that is formed on the metal film made of titanium.

6. 2. The acoustic wave device package of claim 1, wherein the metal layer is a laminate of a metal film made of titanium that is in contact with the other surface of the acoustic wave device, a metal film made of copper that is formed on the metal film made of titanium, and a metal film made of nickel that is formed on the metal film made of copper.

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