JP2006217225A - Manufacturing method of surface acoustic wave device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify processes and furthermore, to obtain a surface acoustic wave device with further reduced size. <P>SOLUTION: The manufacturing method includes an electrode forming step of providing interdigital electrodes 12 onto a piezoelectric substrate 11; a jointing step of connecting the piezoelectric substrate 11 to a wiring board aggregate 15; a first dicing step of dicing only the piezoelectric substrate 11; a sealing step of filling in air gaps, formed by the first dicing step by a gel state curing sheet 16 and curing the gel sheet 16; and a second dicing step of dicing the wiring board aggregate 15 and a sealing member 17, resulting from the cured gel state curing sheet on the aggregate 15 to separate individual devices, and can simplify the processes and reduce the size of the products. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a surface acoustic wave device, particularly for use in a mobile phone or the like.

  In recent years, surface acoustic wave devices have been widely used in electronic devices such as various mobile communication terminal devices. However, in response to the downsizing of devices, the demand for further downsizing of surface acoustic wave devices has increased. It is coming. On the other hand, it has been proposed that surface acoustic wave chips are flip-chip mounted one by one on a wiring board assembly, sealed with resin, and then cut to obtain individual surface acoustic wave devices. In some cases, it takes time to perform flip chip mounting one by one, and it is necessary to take a certain distance between the surface acoustic wave chip and the surface acoustic wave chip for flip chip mounting. There was a problem of getting bigger.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP 2003-17979 A

  An object of the present invention is to obtain a surface acoustic wave device with simplified processes and further miniaturization.

  To achieve the above object, the present invention provides an electrode forming step of providing a comb-shaped electrode on a piezoelectric substrate and a protective film on at least the comb-shaped electrode, and electrically connecting the piezoelectric substrate and the wiring board assembly via bumps. A joining step for mechanical connection, a first dicing step for cutting only the piezoelectric substrate, a sealing step for filling and curing at least a gap formed in the first dicing step with a gel-like curable sheet, and a wiring board A second dicing step of cutting the sealing material in which the aggregate and the gel-like curable sheet thereon are cured and separating the sealing material into individual devices.

  According to the present invention, since it is not necessary to mount the surface acoustic wave chips one by one, the process is simplified, and a surface acoustic wave device having substantially the same bottom area as the surface acoustic wave chip can be obtained.

(Embodiment 1)
Hereinafter, the present invention will be described using the first embodiment.

  FIG. 1 is a diagram illustrating a method for manufacturing a surface acoustic wave device according to Embodiment 1 of the present invention.

  First, an electrode pattern including a comb electrode 12 is formed on a piezoelectric substrate 11 made of φ4 inch lithium tantalate, and a protective film 13 made of SiN is formed on the comb electrode 12. On the other hand, drilling is performed on a glass substrate of about 100 mm square with a laser or the like to form the electrode 22 and the through hole 21 to obtain the wiring board assembly 15.

  Next, as shown in FIG. 1A, the wiring board assembly 15 and the piezoelectric substrate 11 are electrically connected and mechanically connected via bumps 14 made of solder. Here, the diameter of the bump 14 is about 90 μm, and the gap between the wiring board assembly 15 and the piezoelectric substrate 11 is about 60 μm. Since the electrode substrate 22 is formed later by using a glass substrate for the wiring board assembly 15, the positional accuracy of the electrodes can be sufficiently ensured by using the photolithography technique. If this positional accuracy can be formed within an allowable range, a ceramic substrate or the like may be used for the wiring board assembly.

  Usually, in piezoelectric single crystals such as lithium tantalate, the back surface is roughened to reduce the influence of reflection of bulk waves, so the electrode pattern cannot be recognized from the back surface, and cutting in the dicing process performed below Although it is difficult to determine the line, since a circular piezoelectric substrate is bonded to the square wiring board assembly, the cutting line is determined by recognizing the pattern of the wiring board assembly where there is no piezoelectric substrate. Can be done easily. In addition, if the piezoelectric substrate protrudes from the wiring board assembly, the piezoelectric substrate is likely to be cracked in a later process. Therefore, a wiring board assembly having a size equal to or larger than the diameter of the piezoelectric substrate is used. desirable. Note that even if the shape of the wiring board assembly is not rectangular, the same effect can be obtained as long as it is larger than the piezoelectric substrate.

  Next, as shown in FIG. 1B, only the piezoelectric substrate 11 of the bonded substrates is cut with a blade having a blade thickness of about 100 μm (first dicing step). Here, only the piezoelectric substrate 11 means that the piezoelectric substrate 11 is completely cut and separated, but the wiring substrate assembly 15 is not separated. It doesn't matter if it takes. The cut surface of the piezoelectric substrate 11 is preferably flat to the surface on which the electrodes are formed. However, if the blade enters too deep, it will be easily cracked in a later process, so it is desirable that the thickness be about 20% of the thickness of the wiring board assembly 15.

  After that, in a state where the pressure is reduced, the cut piezoelectric substrate side is covered with a gel-like curable sheet 16 and heated to about 80 ° C., and pressure is applied with a roller or the like to fill the gap formed in the first dicing process. Further, by heating to about 150 ° C., it is cured and sealed.

  In this way, it becomes as shown in FIG. At this time, it is desirable that the sealing material 17 having the gel-like curable sheet cured enter inside the end portion of the cut piezoelectric substrate. However, when the sealing material 17 reaches a portion where mechanical vibration such as a comb-shaped electrode or a reflective electrode occurs, the surface acoustic wave is damped and the electrical characteristics fluctuate. Need to not reach.

  Next, as shown in FIG. 1 (d), the wiring board assembly 15 and the sealing material 17 of the same line cut in the first dicing step are cut with a blade having a blade thickness of about 50 μm to obtain individual surface acoustic waves. Separated into devices (second dicing step). In this way, by using a blade with a thinner blade thickness than in the first dicing step in the second dicing step, the cutting width can be narrowed, and the sealing material can be left on the cut surface of the piezoelectric substrate, which is stable. A sealed state is obtained.

  In the sealing as described above, complete hermeticity is not obtained, but since the comb-shaped electrode 12 is covered with the protective film 13, moisture resistance can be secured. Therefore, even if the sealing material 17 is sealed to such an extent that flux during soldering does not enter, there is no practical problem.

  The present invention realizes simplification of the surface acoustic wave device manufacturing process and further miniaturization, and is industrially useful.

The figure explaining the manufacturing method of the surface acoustic wave device in Embodiment 1 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Piezoelectric substrate 12 Comb-shaped electrode 13 Protective film 14 Bump 15 Wiring board aggregate | assembly 16 Gel-like curable sheet 17 Sealing material 21 Through hole 22 Electrode

Claims (5)

A comb-shaped electrode on the piezoelectric substrate, an electrode forming step of providing a protective film on at least the comb-shaped electrode, and a bonding step of electrically and mechanically connecting the piezoelectric substrate and the wiring board assembly via bumps; A first dicing step of cutting only the piezoelectric substrate; a sealing step of filling at least a gap formed in the first dicing step with a gel-like curable sheet; And a second dicing step in which the sealing material on which the gel-like curable sheet is cured is cut and separated into individual devices. The method for manufacturing a surface acoustic wave device according to claim 1, wherein the wiring board assembly is a glass substrate provided with through holes and electrodes. The method for manufacturing a surface acoustic wave device according to claim 1, wherein the cutting width in the second dicing step is narrower than the cutting width in the first dicing step. In the sealing process, cover the cut piezo-electric substrate with a gel-like curable sheet and apply pressure to the cut piezo-electric substrate so that the electrical characteristics are not affected. 2. The method for manufacturing a surface acoustic wave device according to claim 1, wherein a sealing material made of a gel-like curable sheet is inserted inside. 2. The method for manufacturing a surface acoustic wave device according to claim 1, wherein a circular wafer is used as the piezoelectric substrate, and a square substrate having a size equal to or larger than the diameter of the piezoelectric substrate is used as the wiring board assembly.

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