JP2009164826A - Silicon microphone package and mounting method of silicon microphone chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variation of microphone characteristics of a silicon microphone chip in a silicon microphone package which mounts the silicon microphone chip comprised by providing a diaphragm so as to cover an inner hole of a support section on a mounting surface of a substrate. <P>SOLUTION: In the silicon microphone package 1, the support section 11 of the silicon microphone chip 5 is attached on the mounting surface 3a of the substrate 21 by a silicon thermosetting resin 29 in such a state that a diaphragm 15 of the silicon microphone chip 5 faces to the mounting surface 3a of the substrate 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a silicon microphone package and a mounting method of a silicon microphone chip provided for the silicon microphone package.

Conventionally, a silicon microphone chip provided with a diaphragm for detecting pressure fluctuations such as sound by vibration, such as a silicon condenser microphone, is mounted on a substrate mounting surface as in, for example, Patent Documents 1 and 2, and the silicon microphone together with this substrate. Configure the package. This silicon microphone chip is configured by providing a diaphragm so as to cover an inner hole of an annular support portion made of silicon.
On the other hand, substrates composed of ceramic, plastic, and glass epoxy are widely used as substrates on which silicon microphone chips are mounted. In the conventional silicon microphone package, the silicon microphone chip is attached to the mounting surface of the substrate with an epoxy or acrylic thermosetting resin.
JP-T-2004-537182 JP-T-2003-508997

  However, the coefficient of thermal expansion differs greatly between silicon forming the silicon microphone chip and materials such as ceramic, plastic, and glass epoxy constituting the substrate, and the epoxy and acrylic thermosetting resins have a large elastic modulus. For example, the elastic modulus of the epoxy thermosetting resin is about 3600 MPa, and the elastic modulus of the acrylic thermosetting resin is about 470 MPa. For this reason, when a conventional silicon microphone package is heated and cooled during use or manufacture, stress is applied to the diaphragm of the silicon microphone chip, and there is a problem that the microphone characteristics fluctuate due to deformation of the diaphragm based on this stress.

For example, when a silicon microphone chip is attached to a substrate, the substrate is thermally expanded or contracted by heat curing and cooling of the thermosetting resin, and as a result, stress generated at that time is applied to the diaphragm. As a result, the microphone characteristics change during the manufacture of the silicon microphone package, and the target microphone characteristics may not be obtained.
In addition, when the manufactured silicon microphone package is mounted on another mounting substrate, the diaphragm is affected by stress as described above, and the target microphone characteristics may not be obtained.
Note that the change in the microphone characteristics includes, for example, that when a tensile stress is generated in the diaphragm, the amount of bending of the diaphragm with respect to pressure fluctuations such as sound is reduced, so that the microphone sensitivity is lowered.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a silicon microphone package and a method of mounting a silicon microphone chip that can suppress fluctuations in microphone characteristics.

In order to solve the above problems, the present invention proposes the following means.
In the silicon microphone package of the present invention, a silicon microphone chip having a diaphragm so as to cover the inner hole of the support portion is mounted on the mounting surface of the substrate, and the diaphragm is opposed to the mounting surface of the substrate. The support portion is attached to the mounting surface of the substrate with a silicone-based thermosetting resin.

  The elastic modulus of the silicone-based thermosetting resin used in the silicon microphone package according to the present invention is smaller than that of the support portion made of silicon. For this reason, even if the thermal expansion coefficient is greatly different between the substrate and the silicon microphone chip, when the silicon microphone package is heated and cooled, the difference between the thermal expansion coefficient is determined between the substrate and the silicon microphone chip. The generated stress can be absorbed in the silicone-based thermosetting resin.

  The silicon microphone package includes a lid body that covers the mounting surface so as to include the silicon microphone chip and forms a hollow cavity with the substrate, and at least one of the substrate and the lid body. An opening that communicates the cavity with the outside may be formed.

In this silicon microphone package, the pressure fluctuation such as sound reaches the diaphragm of the silicon microphone chip from the outside of the cavity through the opening, so that the pressure fluctuation can be detected.
In this silicon microphone package, since the silicon microphone chip is disposed in the cavity, the diaphragm can be protected from dust, water droplets, and the like outside the cavity. Therefore, it is possible to prevent the microphone characteristics of the silicon microphone chip from fluctuating or malfunctioning based on these dust and water droplets.

  The silicon microphone chip mounting method of the present invention is a method of mounting a silicon microphone chip in which a diaphragm is provided on the mounting surface of the substrate so as to cover the inner hole of the support portion, and is mounted on the mounting surface of the substrate. The silicone thermosetting resin is applied, the support portion is disposed on the silicone thermosetting resin so that the diaphragm faces the mounting surface, and the silicone thermosetting resin is heated. The support portion is attached to the mounting surface by curing.

By implementing this silicon microphone chip mounting method, the above-described silicon microphone package can be manufactured.
Moreover, in this silicon microphone chip mounting method, the substrate and the silicon microphone chip are cooled after the silicone-based thermosetting resin is cured. Here, the elastic modulus of the silicone-based thermosetting resin is smaller than that of the substrate or the silicon microphone chip as described above. For this reason, even when a silicon microphone chip is mounted on a substrate, the silicone-based thermosetting resin causes stress generated between the substrate and the silicon microphone chip based on the difference in thermal expansion coefficient between the substrate and the silicon microphone chip. Can be absorbed.

  According to the present invention, the stress generated between the substrate and the silicon microphone chip can be absorbed in the silicone-based thermosetting resin based on the difference in thermal expansion coefficient between the substrate and the silicon microphone chip. The deformation of the diaphragm can be suppressed, and the fluctuation of the microphone characteristics of the silicon microphone chip can be suppressed.

Hereinafter, a silicon microphone package according to an embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a silicon microphone package 1 according to this embodiment is configured by providing a silicon microphone chip 5 and an LSI chip 7 on a mounting surface 3a in a housing 3 having a hollow cavity S.
The silicon microphone chip 5 is made of silicon and has an annular support portion 11 having a substantially circular inner hole 11a in plan view, a substantially disc-shaped back plate 13 disposed so as to cover the upper end of the inner hole 11a, It is comprised from the disk-shaped diaphragm 15 arrange | positioned so that the inner side 11a side of the support part 11 may be distribute | arranged substantially parallel to the back plate 13, and may cover the inner hole 11a. The back plate 13 is a conductive semiconductor film formed of, for example, polycrystalline silicon in a substantially disc shape. The back plate 13 has a plurality of through holes 13a penetrating in the thickness direction. Yes. The diaphragm 15 is a conductive semiconductor film in which, for example, polycrystalline silicon doped with an impurity such as phosphorus (P) is formed in a disc shape.

In the silicon microphone chip 5, a bias voltage can be applied between the back plate 13 and the diaphragm 15, and the capacitance change between the back plate 13 and the diaphragm 15 based on the vibration of the diaphragm 15. Thus, pressure fluctuations such as sound are detected.
The LSI chip 7 includes, for example, an amplifier circuit for amplifying an electric signal from the silicon microphone chip 5, an A / D converter for processing the electric signal as a digital signal, a DSP (digital signal processor), and the like. It is configured.
The silicon microphone chip 5 and the LSI chip 7 are electrically connected by a wire 9 having a loop shape curved upward between them.

The housing 3 includes a box-type substrate (substrate) 21 on which the silicon microphone chip 5 and the LSI chip 7 are mounted, and a lid body 23 that covers the mounting surface 3 a of the box-type substrate 21 so as to include the silicon microphone chip 5 and the LSI chip 7. It has.
The box-type substrate 21 forms a so-called multilayer wiring substrate such as a ceramic substrate, and surrounds the bottom wall portion 25 that is formed in a plate shape and forms the mounting surface 3 a of the housing 3, the silicon microphone chip 5, and the LSI chip 7. As shown, an annular side wall portion 27 protruding from the mounting surface 3a is provided. In addition, the side wall part 27 protrudes upwards rather than the wire 9 for electrical connection mentioned above.

For example, when the box-type substrate 21 is formed of a ceramic multilayer wiring board, a plurality of ceramic sheets having a predetermined pattern of conductive paths forming a wiring portion of the box-type substrate 21 are stacked, so that the box-type substrate 21 is Can be manufactured. And the side wall part 27 can be formed by laminating | stacking the ceramic sheet formed cyclically | annularly.
The silicon microphone chip 5 and the LSI chip 7 described above are disposed with a gap between the inner peripheral surface of the side wall portion 27 of the box-type substrate 21. The box substrate 21 is electrically connected to the silicon microphone chip 5 and the LSI chip 7 by arranging a wire 28 between the mounting surface 3 a and the LSI chip 7.

The lid body 23 is formed of a conductive plate material such as a copper material, for example, and is formed on the upper end surface 27 a of the side wall portion 27 so as to cover the mounting surface 3 a of the box-type substrate 21, the silicon microphone chip 5, and the LSI chip 7. It is arranged. That is, the lid body 23 forms a hollow cavity S together with the box-type substrate 21 by closing the opening of the box-type substrate 21.
The lid 23 is formed with an opening 23a that allows the cavity S to communicate with the outside.

The silicon microphone chip 5 and the LSI chip 7 are affixed to the mounting surface 3 a of the box-type substrate 21 with a silicone-based thermosetting resin 29.
This silicone-based thermosetting resin 29 is arranged so as to fill the space between the inner hole 11a of the silicon microphone chip 5 and the box-shaped substrate 21. When this is cured, the inner hole 11a and the diaphragm 15 are filled. And the cavity S1 defined by the mounting surface 3a of the box-type substrate 21 is almost sealed to the outside. Note that when the cavity S1 is actually sealed, a pressure difference is generated on both sides of the diaphragm 15 based on changes in temperature and atmospheric pressure. For example, a portion between the box-type substrate 21 and the support 11 is used. In some cases, the silicone-based thermosetting resin 29 is not applied only, and pores that allow the cavity S1 to communicate outwardly may be formed using the unapplied portion.

  Specific examples of the silicone-based thermosetting resin 29 include model number “DA6501” manufactured by Toray Dow Corning Co., Ltd. The silicone-based thermosetting resin 29 is cured by maintaining a high temperature of 150 ° C. for 60 minutes. The elastic modulus (Young's modulus) of the silicone-based thermosetting resin 29 in the cured state is 0.8 MPa. It is. That is, the silicone-based thermosetting resin 29 is very small compared to the elastic modulus of the epoxy-based or acrylic-based thermosetting resin conventionally used for die bonding of the silicon microphone chip 5.

When manufacturing the silicon microphone package 1 configured as described above, first, the silicon microphone chip 5 is mounted on the box-type substrate 21. This mounting method will be described below.
In this mounting method, first, a silicone-based thermosetting resin 29 is applied to the mounting surface 3 a of the box-type substrate 21. Subsequently, the support part 11 is arrange | positioned on the silicone type thermosetting resin 29 so that the diaphragm 15 may oppose the mounting surface 3a. And the support part 11 is affixed on the mounting surface 3a of the box-type board | substrate 21 by heating and hardening the silicone type thermosetting resin 29. FIG. In the case of this heat-curing, it is possible to heat from room temperature (25 ° C.) to a high temperature of 150 ° C. and maintain this heating state for 60 minutes. The LSI chip 7 is attached by a silicone-based thermosetting resin 29 in the same manner as the silicon microphone chip 5, and this attachment is performed simultaneously with the attachment of the silicon microphone chip 5.

After the silicon microphone chip 5 and the LSI chip 7 are attached to the mounting surface 3a of the box-type substrate 21, the silicon microphone chip 5, the LSI chip 7 and the box-type substrate 21 are cooled, so that the silicon microphone chip 5 and the LSI chip 7 The mounting of the LSI chip 7 is completed.
In this cooling, a stress is generated between the silicon microphone chip 5 and the box substrate 21 based on the difference in thermal expansion coefficient between the silicon microphone chip 5 and the box substrate 21. Here, since the elastic modulus of the silicone-based thermosetting resin 29 is smaller than that of the box-type substrate 21 and the silicon microphone chip 5 as described above, this stress can be absorbed by the silicone-based thermosetting resin 29.

After the above-described mounting of the silicon microphone chip 5 and the LSI chip 7 is completed, wires 9 and 28 are respectively connected between the silicon microphone chip 5 and the LSI chip 7 and between the LSI chip 7 and the box substrate 21. The lid 23 covering the silicon microphone chip 5 and the LSI chip 7 is fixed to the upper end surface 27 a of the box-type substrate 21, thereby completing the manufacture of the silicon microphone package 1.
In the silicon microphone package 1 manufactured as described above, when pressure fluctuations such as sound reach the diaphragm 15 of the silicon microphone chip 5 from the outside through the opening 23a of the lid 23, this pressure is reduced. The pressure fluctuation can be detected by vibrating the diaphragm 15 based on the fluctuation.

According to the silicon microphone package 1, since the elastic modulus of the silicone-based thermosetting resin 29 is smaller than that of the support portion 11, even if the silicon microphone package 1 is heated and cooled during use, the silicon microphone chip 5 and the box shape are used. The stress generated between the silicon microphone chip 5 and the box-type substrate 21 based on the difference in thermal expansion coefficient with the substrate 21 can be absorbed by the silicone-based thermosetting resin 29. This stress is also generated when the silicon microphone chip 5 is mounted as described above, but is similarly absorbed by the silicone-based thermosetting resin 29.
From the above, the deformation of the diaphragm 15 based on the stress can be suppressed, and the microphone characteristics of the silicon microphone chip 5 can be suppressed from fluctuating.

  Further, according to the silicon microphone package 1, since the silicon microphone chip 5 is disposed in the cavity S, the diaphragm 15 can be protected from dust, water droplets, etc. outside the cavity S. Therefore, it is possible to prevent the microphone characteristics of the silicon microphone chip 5 from fluctuating or malfunctioning based on these dusts and water droplets.

In the above-described embodiment, the opening 23 a that communicates the cavity S outward is formed in the lid 23, but is formed in, for example, the bottom wall 25 and the side wall 27 of the box-type substrate 21. May be.
Further, the box-type substrate 21 on which the silicon microphone chip 5 and the LSI chip 7 are mounted is configured by the bottom wall portion 25 and the side wall portion 27, but is configured only by the bottom wall portion 25 forming the mounting surface 3a. It doesn't matter. That is, the housing having the hollow cavity S may be configured by a substantially plate-like substrate. In this case, for example, a lid having a recess is prepared, and this lid may be arranged on the mounting surface of the substrate so as to include the silicon microphone chip 5 and the LSI chip 7.

Furthermore, although the silicon microphone package 1 is configured to include the lid that forms the hollow cavity S together with the substrate, it is not necessary to form the cavity S in particular. Therefore, for example, as shown in FIG. 2, the silicon microphone package 31 is configured by attaching the silicon microphone chip 5 and the LSI chip 7 to the mounting surface 33 a of the substantially plate-like substrate 33 with the silicone-based thermosetting resin 29. It is good.
The silicon microphone packages 1 and 31 include the LSI chip 7. At least the silicon microphone chip 5, the substrates 21 and 33 on which the silicon microphone chip 5 is mounted, and the silicon microphone chip 5 are attached to the mounting surfaces 3a and 33a. It is only necessary to include the silicone-based thermosetting resin 29 for the purpose.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

1 is a schematic sectional side view showing a silicon microphone package according to an embodiment of the present invention. It is a schematic sectional side view which shows the silicon microphone package which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 ... Silicon microphone package, 3a ... Mounting surface, 5 ... Silicon microphone chip, 11 ... Support part, 11a ... Inner hole, 15 ... Diaphragm, 21 ... Box-type board | substrate (board | substrate), 23 ... Cover, 23a ... Opening 29, silicone thermosetting resin, 33, substrate, 33a, mounting surface, S, cavity

Claims (3)

A silicon microphone package in which a silicon microphone chip provided with a diaphragm so as to cover the inner hole of the support portion is mounted on the mounting surface of the substrate,
The silicon microphone package, wherein the support portion is bonded to the mounting surface of the substrate with a silicone-based thermosetting resin with the diaphragm facing the mounting surface of the substrate. A lid that covers the mounting surface so as to include the silicon microphone chip and forms a hollow cavity with the substrate;
The silicon microphone package according to claim 1, wherein an opening for communicating the cavity portion outward is formed in at least one of the substrate and the lid. A mounting method of a silicon microphone chip in which a silicon microphone chip having a diaphragm so as to cover the inner hole of the support portion is mounted on the mounting surface of the substrate,
A silicone thermosetting resin is applied to the mounting surface of the substrate,
The support portion is disposed on the silicone-based thermosetting resin so that the diaphragm faces the mounting surface,
A method of mounting a silicon microphone chip, wherein the silicone thermosetting resin is heated and cured to attach the support portion to the mounting surface.

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