JP2005027229A - Surface acoustic wave device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a means for downsizing a SAW device and lowering its back. <P>SOLUTION: A surface acoustic wave device element is bonded to an insulating substrate through metal bumps by a flip chip method. An insulating resin is applied to the surface acoustic wave device element and the insulating substrate and is cured by heat to form the surface acoustic wave device which is provided with an airtight space between the surface acoustic wave device element and the insulating substrate. A multilayer metal film, composed of at least two layers, a first metal film exhibiting a high adhesiveness and a second metal layer, is provided on the outer surface of the insulating resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface acoustic wave device and a manufacturing method thereof, and more particularly to a surface acoustic wave device using an insulating film or an insulating resin for simple sealing and having a laminated metal film attached to the surface and a manufacturing method thereof.

In recent years, surface acoustic wave devices (hereinafter referred to as SAW devices) have been widely used in the communication field, and since they have excellent characteristics such as high performance, small size, and mass productivity, they are often used particularly for mobile phones and wireless LANs. Yes.
FIG. 7 is a cross-sectional view showing a configuration of a conventional SAW device, in which a SAW device element 21 is accommodated in a ceramic package 22, and a concave portion of the ceramic package 22 and a bottom surface of the SAW device element 21 are used with an adhesive. After bonding and fixing, the pad electrode (not shown) of the SAW device and the electrode 23 provided on the step portion of the ceramic package 22 are connected by the bonding wire 24. Then, the metallization 25 and the metal lid 26 formed on the peripheral edge of the upper part of the ceramic package 22 are hermetically sealed using means such as resistance welding to constitute a SAW device.

The reason for hermetically sealing the interior of the ceramic package 22 with a gas such as dry nitrogen is that, as is well known, in order to prevent frequency fluctuations due to oxidation of the electrodes of the SAW device element 21 and environmental changes such as temperature changes. This is because dew condensation is caused by the above and performance deterioration due to water droplets appearing on the SAW device element 21 is prevented.
Although the SAW device using the ceramic package is excellent in hermeticity, there is a problem that it is difficult to satisfy the recent demands for miniaturization and cost reduction. As means for solving this problem, a SAW device in which a SAW device element is formed of an insulating film and sealed with a frame-like insulating wall and lid, and a method for manufacturing the SAW device, are disclosed in Japanese Patent Application Laid-Open No. 2000-114918. Yes.

Japanese Patent Laid-Open No. 2000-114918 will be briefly described. As shown in FIG. 8A, electrodes 32 for transmitting and receiving surface acoustic waves are arranged in a matrix on the wafer 31, and as shown in FIG. 8B, all the electrodes 32 on the wafer 31 are exposed to a photosensitive film. As shown in FIG. 8C, a frame-shaped first insulating wall 34 surrounding the electrode 32 is formed using a photoengraving technique (photolithography technique). Then, as shown in FIG. 8D, a photosensitive film 35 is mounted on the first insulating wall 34, and a space 36 is provided between the electrodes 32. Next, a second insulating lid 37 for the first wall 34 is formed by photolithography, and individual chips (SAW devices) are formed by cutting and dividing the positions of the separation lines 38 with a dicing saw. .

  FIG. 9 is a perspective view showing the configuration of the SAW device manufactured using the manufacturing method shown in FIG. 8, and is a frame-like insulating wall so as to cover the surrounding space of the electrodes arranged on the piezoelectric substrate 31. A simple package including 34 and an insulating lid 35 is formed. The surface of the simple package is covered with a metal film for preventing moisture from entering the inside, and also functions as an electromagnetic shield by making the metal film conductive with the ground potential.

JP 2000-114918 A

However, when a metal film is attached to the insulating resin as shown in FIG. 9, peeling easily occurs in the scratch test, or cracks or the like occur. As a result, there is a problem that moisture penetrates into the simple package and receives electromagnetic influence from electronic components around the SAW device.

  In FIG. 10, a metal film of chromium (Cr), titanium (Ti), aluminum (Al), copper (Cu), etc. is deposited on an insulating resin plate with a film thickness of 0.1 μm and 5 μm by means such as vapor deposition. Scratch test (the scratch test includes the pencil method JIS K5600-5-4 and the load needle method K5600-5-5, but the latter was used), the crack shown in FIG. 11A, and FIG. It is the figure which put together the result of having observed the thin film-like peeling etc. which are shown in FIG. Here, the marks “◯” and “X” indicate the case where no peeling occurred and the case where it occurred in the scratch test, respectively. FIG. 10 shows that aluminum and copper are vulnerable to the scratch test regardless of the film thickness. On the other hand, chromium is strong in the scratch test regardless of the film thickness, but cracks occur as the film thickness increases. In addition, in the case of titanium, peeling does not occur in the scratch test at a film thickness of 0.1 μm, but peeling occurs when the film thickness increases to 5 μm, and thin film peeling also occurs. Peeling in the scratch test indicates that the adhesion strength of the metal film is weak and cannot be practically used.

  The present invention has been made to solve the above problems, and an object thereof is to provide a SAW device in which a SAW device element is accommodated in a resin package in which a metal film is firmly adhered, and a method for manufacturing the SAW device.

In order to achieve the above object, the surface acoustic wave device according to the present invention and the manufacturing method thereof according to claim 1 include a printed circuit board on which predetermined wiring is provided, and a surface acoustic wave element mounted thereon by flip-chip mounting. And an insulating airtight member that covers the upper surface of the surface acoustic wave element and the printed circuit board so as to secure an airtight space, and a metal film attached to the outer surface of the airtight member. In the wave device, the metal film is formed by sequentially attaching at least a first metal film excellent in adhesion to the airtight member and a second metal film made of a metal different from the first metal film. The surface acoustic wave device is a multilayer metal film including a structure.
According to a second aspect of the present invention, in the surface acoustic wave device according to the first aspect, the first metal film is a metal containing chromium, titanium, or nickel as a main component.
A third aspect of the present invention is the surface acoustic wave device according to the first or second aspect, wherein the second metal film is a metal mainly composed of aluminum or copper.
The invention according to claim 4 is the surface acoustic wave device according to any one of claims 1 to 3, wherein an outer surface of the metal film is covered with an insulating resin.
According to a fifth aspect of the present invention, when the thickness of the first metal film is H1, and the thickness of the second metal film is H2,
H1 ≦ 0.5μm, 0.5μm <H2 ≦ 50μm
5. The surface acoustic wave device according to claim 1, wherein each film thickness is set so as to satisfy the above.
According to a sixth aspect of the present invention, a surface acoustic wave element is flip-chiped in a matrix form through a metal bump on a mounting substrate base material having an external terminal and a plurality of internal conductors and wiring patterns that are electrically connected to the external terminal. Bonding, and attaching an insulating film or insulating resin on the surface acoustic wave element and thermosetting it to form an airtight space between the surface acoustic wave element and the mounting substrate base material and sealing A surface acoustic wave device comprising: a step of forming a metal film on an outer surface of the thermally cured insulating film or resin; and a step of dividing the mounting substrate base material into pieces. A step of cutting the insulating film or resin after the thermosetting film or resin is cured, and cutting the mounting substrate base material so as not to be separated; and the thermosetting insulating property A step of depositing a first metal film having good adhesion on a film or a resin, a step of depositing a second metal film on the first metal film, and the thermosetting insulating film or resin. A method of manufacturing a surface acoustic wave device, comprising a step of cutting the mounting substrate base material into a piece that is narrower than a cutting width obtained by cutting the substrate.
According to a seventh aspect of the present invention, a surface acoustic wave device is flip-chiped in a matrix form through metal bumps on a mounting substrate base material having external terminals and having a plurality of internal conductors and wiring patterns that are electrically connected to the external terminals. In addition, the insulating film or insulating resin is attached on the surface acoustic wave element and thermally cured, and an airtight space is formed between the surface acoustic wave device element and the mounting substrate base material to seal. In the method of manufacturing a surface acoustic wave device, comprising: a step; a step of forming a metal film on an outer surface of the thermally cured insulating film or resin; and a step of dividing the mounting substrate base material into pieces. After thermally curing the insulating film or resin, cutting the insulating film or resin and making a notch so that the mounting substrate base material is not separated; and the thermosetting A step of depositing a first metal film having good adhesion on an insulating film or resin, a step of depositing a second metal film on the first metal film, the inside of the notch and the second A step of filling a resin so as to cover the metal film, and a step of cutting the mounting substrate base material by a width narrower than a cutting width obtained by cutting the heat-cured insulating film or resin and dividing the substrate into pieces. A method of manufacturing a surface acoustic wave device.
It may be configured.

  Since the present invention is configured as described above, the invention described in claim 1 exhibits excellent effects of preventing moisture from entering the package and preventing electromagnetic shielding from surrounding electrical components. Since the invention according to the second and third aspects specifies the metal film that adheres firmly to the resin package, the SAW device can be easily realized. The invention according to claim 4 provides means for further strengthening the laminated metal film. The invention according to claim 5 has an excellent effect that the SAW device can be easily realized because the thickness of each of the first and second metal films is specified. The inventions according to claims 6 and 7 show the manufacturing method of the simple package type SAW device, and therefore, there is an excellent effect that this type of SAW device can be easily realized.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

  FIG. 1 is a diagram showing the configuration of an embodiment of a surface acoustic wave device according to the present invention, where FIG. 1 (a) is a perspective view, FIG. 1 (b) is a cross-sectional view, and FIG. FIG. A connection terminal 2 and an external terminal 3 are formed on the upper surface and the back surface of an insulating substrate 1, for example, a ceramic substrate, and an internal conductor 4 that conducts between the connection terminal 2 and the external terminal 3 is formed. Then, the SAW device element 6 is bonded to the connection terminal 2 via the metal bump 5 by the flip chip method, and the insulating resin 7 is attached to the SAW device element 6 in the face-down state and the upper surface of the insulating substrate 1. By heat curing, an airtight space 8 is formed between the SAW device element 6 and the upper surface of the insulating substrate 1. Further, a first metal film 9a having good adhesion to the insulating resin is attached to the outer surface of the thermally cured insulating resin 7, and a second metal film 9b is laminated on the first metal film 9a. Thus, the SAW device is completed. The laminated metal film 9 (9a, 9b) is electrically connected to a grounding conductor provided on the insulating substrate 1.

  As a result of various experiments, chromium, titanium, nickel, etc., which have good adhesion to the insulating resin 7 are suitable as the first metal film 9a. However, when these metal films are thickened, cracks or thin film-like peeling occurs. And is weaker to the scratch test. However, when the film is thinned, the mechanical strength can be prevented from being lowered, but the original function of preventing moisture from entering cannot be obtained sufficiently. An ideal film can be obtained by laminating an aluminum or copper film as the second metal film 9b on the first metal film 9a in order to compensate for these weak points.

  FIG. 2 shows an example of a laminated metal film. A is a case where the first metal film 9a is a chromium film of 0.1 μm and the second metal film 9b is an aluminum film of 4 μm, and peeling does not occur in the scratch test. The metal film did not peel off as a thin film. B shows a case where the first metal film 9a is a chromium film of 0.2 μm and the second metal film 9b is an aluminum film of 4 μm. No peeling occurred in the scratch test, and no metal film was peeled off. . C is a case where the first metal film 9a is a chromium film of 0.1 μm and the second metal film is an aluminum film of 10 μm. Similarly, no peeling occurs in the scratch test, and no metal film is peeled off. It was.

  In the example of the laminated metal film of FIG. 2, copper was used instead of aluminum as the second metal film, and the chromium film / copper film were tested at 0.1 μm / 4 μm, 0.2 μm / 4 μm, and 0.1 μm / 10 μm, respectively. However, good results were obtained as in the case of aluminum.

  Next, titanium was used instead of chromium as the first metal film, and a laminated film in which an aluminum film or a copper film was laminated thereon as the second metal film was formed, and scratch tests and cracks were investigated. Almost the same results as in the case of the lamination of the chromium film and the copper film were obtained.

  It has also been found that even if nickel is used as the first metal film, it is firmly adhered to the resin. Although a film in which the thickness of the second metal film (Al, Cu) was increased to about 50 μm was prototyped, no peeling or the like occurred.

  As shown in FIG. 1B, an airtight space 8 is formed between the electrode surface of the SAW device element 6 and the upper surface of the insulating substrate 1 with the insulating resin 7, and a laminated metal is formed on the outer surface of the insulating resin 7. By attaching the film 9, it is possible to prevent moisture from entering the hermetic space 8 and to completely prevent electromagnetic influences from surrounding electronic components on which the SAW device is mounted.

As a method of manufacturing the SAW device shown in FIG. 1, each connection terminal (not shown) of the mounting substrate base material 1P in which the insulating substrate 1 is arranged in a matrix as shown in FIG. As shown in FIG. 4B, the SAW device element 6 is bonded by the flip-chip method through the metal bumps 5, and the face-down SAW device element 6 and the upper surface of the mounting substrate base material 1P are attached to the same figure (FIG. As shown in c), the insulating resin 7 is adhered and thermally cured to form an airtight space 8 between each SAW device element 6 and the upper surface of the mounting substrate base material 1P. Further, as shown in FIG. 3 (d), a notch having a predetermined width is made at a depth corresponding to the thickness of the thermally cured insulating resin 7 so as not to cut the mounting substrate base material 1P. Then, as shown in FIG. 4E, a first metal film having good adhesion is attached on the outer surface of each insulating resin 7 by means such as vapor deposition, and further on the first metal film. A laminated metal film 9 is formed by attaching a second metal film. Then, the mounting substrate base material 1P is cut along a one-dot chain line with a width narrower than the cut width put in the insulating resin 7, and divided into individual pieces, thereby completing the SAW device.

  As described above, the first metal film is made of chromium, titanium, or nickel with a thickness of 0.5 μm or less, and the second metal film is made of aluminum or copper with a thickness of about 0.5 μm to 50 μm. When the thickness is increased, a strong laminated film can be formed. FIG. 4 is a photograph of the upper surface of a SAW device manufactured with a chromium film thickness of 0.1 μm and an aluminum film thickness of 4 μm, and it can be confirmed that no peeling of the film occurs.

FIG. 5 is a diagram showing the configuration of a second embodiment according to the present invention. FIG. 5A is a perspective view, FIG. 5B is a sectional view, and FIG. FIG. The difference from the first embodiment shown in FIG. 1 is that the laminated metal film 9 is coated with a resin 10 to strengthen the laminated metal film 9. As a manufacturing method, the step shown in FIG. 6 is added after the step shown in FIG. That is, the mounting substrate is filled with a resin 10 so as to cover the inside of the notch in FIG. 3E and the second metal film 9 and cured, and is narrower than the notch width put in the insulating resin 7. The base material 1P is cut along an alternate long and short dash line and divided into individual pieces to complete the SAW device. By covering the laminated metal film 9 with the resin 10, it is possible to prevent the second metal film (aluminum, copper) from being deteriorated or oxidized.

  Although described as a SAW device in FIG. 1, it goes without saying that this includes all SAW devices such as SAW resonators, multimode SAW filters, and transversal SAW filters. In addition, we have explained that a simple package is made using an insulating resin, but heat curing is performed using an insulating film, and the above-mentioned metal film is laminated and adhered to the SAW device.

(A) is a perspective view of a SAW device according to the present invention, (b) is a cross-sectional view of QQ, and (c) is a cross-sectional view of XX. It is a figure which shows each film thickness of the laminated | stacked metal film, a scratch test, and the presence or absence of a crack. (A), (b), (c), (d), (e) is sectional drawing which shows the manufacturing process of the SAW device based on this invention. It is a photograph of the laminated metal film (Al / Cr) formed on the resin. It is a figure which shows the structure of the surface acoustic wave device of 2nd Example which concerns on this invention, (a) is a perspective view, (b) is sectional drawing of QQ, (c) is sectional drawing of XX. is there. It is sectional drawing which shows the manufacturing process of the SAW device of 2nd Example based on this invention. It is sectional drawing which shows the structure of the conventional surface acoustic wave device using a ceramic package. (A), (b), (c), (d), (e) is a figure which shows the process of forming a simple package using an insulating film. It is a perspective view of the surface acoustic wave device which attached the metal film to the simple package of the insulating film. It is a figure which shows the scratch test of the various metal films adhering on resin, and the state of a metal film. (A) is a photograph showing a crack of a chromium film (5 μm) deposited on the resin, and (b) is a photograph showing a crack of a titanium film (3 μm) deposited on the resin.

Explanation of symbols

1 .. Piezoelectric substrate 1P .. Mounting substrate base material 2. Connection terminal 3. External terminal 4. Internal conductor 5. Metal bump 6. SAW device element 7. Insulating resin 8. Airtight space 9 ..Laminated metal film 9a..first metal film 9b..second metal film 10..resin

Claims (7)

A printed circuit board on which a predetermined wiring is provided, a surface acoustic wave element flip-chip mounted on the printed circuit board, and an insulating covering the upper surface so as to secure an airtight space between the surface acoustic wave element and the printed circuit board A surface acoustic wave device comprising a gas-tight airtight member and a metal film attached to the outer surface of the airtight member,
The metal film includes a multilayer metal film including a structure in which at least a first metal film having excellent adhesion to the hermetic member and a second metal film made of a metal different from the first metal film are sequentially attached. A surface acoustic wave device characterized by the above. 2. The surface acoustic wave device according to claim 1, wherein the first metal film is a metal containing chromium, titanium, or nickel as a main component. 3. The surface acoustic wave device according to claim 1, wherein the second metal film is a metal containing aluminum or copper as a main component. 4. The surface acoustic wave device according to claim 1, wherein an outer surface of the metal film is covered with an insulating resin. When the thickness of the first metal film is H1, and the thickness of the second metal film is H2,
H1 ≦ 0.5μm, 0.5μm <H2 ≦ 50μm
The surface acoustic wave device according to claim 1, wherein each film thickness is set so as to satisfy the above. A surface acoustic wave element is bonded in a matrix by a flip chip method on a mounting board base material having external terminals and a plurality of internal conductors and wiring patterns electrically connected to the external terminals via metal bumps. An insulating film or an insulating resin is attached on the element and thermally cured to form an airtight space between the surface acoustic wave element and the mounting substrate base material, and the thermally cured insulating property In a method for manufacturing a surface acoustic wave device comprising a step of forming a metal film on the outer surface of a film or a resin, and a step of dividing the mounting substrate base material into pieces.
After thermally curing the insulating film or resin, cutting the insulating film or resin and making a notch so that the mounting substrate base material is not separated; and on the thermally cured insulating film or resin A step of attaching a first metal film having good adhesion, a step of attaching a second metal film on the first metal film, and a cutting width obtained by cutting the thermally cured insulating film or resin. A method of manufacturing a surface acoustic wave device, comprising a step of cutting the mounting substrate base material with a narrower width and dividing it into pieces. A surface acoustic wave element is bonded in a matrix by a flip chip method on a mounting board base material having external terminals and a plurality of internal conductors and wiring patterns electrically connected to the external terminals via metal bumps. An insulating film or an insulating resin is attached on the element and thermally cured to form an airtight space between the surface acoustic wave device element and the mounting substrate base material, and the thermally cured insulation In a method of manufacturing a surface acoustic wave device comprising a step of forming a metal film on the outer surface of a conductive film or resin, and a step of dividing the mounting substrate base material into pieces.
After thermally curing the insulating film or resin, cutting the insulating film or resin and making a notch so that the mounting substrate base material is not separated; and on the thermally cured insulating film or resin A step of attaching a first metal film having good adhesion, a step of attaching a second metal film on the first metal film, and covering the inside of the notch and the second metal film. And a step of cutting the mounting substrate base material with a width narrower than a cutting width obtained by cutting the heat-cured insulating film or resin, and dividing the mounting substrate base material into pieces. Manufacturing method for surface acoustic wave devices.

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