KR20090041041A - Silicon microphone package and fabricating method thereof - Google Patents

Abstract

A silicon microphone package and a manufacturing method thereof are provided to reduce the size of the silicon microphone package by equipping the passive circuit part inside. A silicon microphone package comprises a substrate(100), a silicon microphone(110), an active circuit(120), a case, and a touch pad(170). The passive circuit part consisting of passive devices is built in the substrate. The negative pressure tube through-hole(180) in which the external sound pressure is induced is formed in the substrate. The silicon microphone is welded so that the vibration plate vibrated by the outside sound pressure faces with the substrate. The active circuit part is welded on the substrate and converts the vibratory signal of the silicon microphone into the electric signal. The case is formed along the outer ring of substrate. The passive circuit part is made of a resistance(161) and a capacitor(164).

Description

Silicon microphone package and fabrication method thereof

The present invention relates to a silicon microphone package and a method of manufacturing the same.

In general, a microphone is a type of sensor that detects a vibration of sound or ultrasonic waves and converts the signal into an electrical signal corresponding to the vibration of a medium.

The microphone is induced by vibrating a diaphragm equipped with a coil using a carbon-type electrical resistance characteristic of carbon particles, a crystalline form using a piezoelectric effect of Rochelle salt, and a coil mounted in a magnetic field according to a method of converting mechanical vibration into an electrical signal. It is divided into a movable coil type for generating an electric current, a speed type for generating an induced current when the metal film installed in the magnetic field vibrates by sound waves, and a condenser type for changing capacitance due to vibration of the film by sound waves.

Such a microphone is used as a sound input device, and is used in a recorder, a telephone, a loudspeaker, a hearing aid, and the like. In the related art, an electret condenser microphone (ECM) having a simple structure and low cost has become mainstream.

However, since the electret is made of a polymer-based thin film such as Teflon or FET, which is a fluorocarbon organic compound, it is vulnerable to heat and moisture.

Therefore, there is a disadvantage in that the characteristics of the microphone change according to the surrounding environment, and the surface mount technology (SMT) cannot be applied because it is sensitive to temperature.

In order to solve this problem, a silicon microphone using a micro-machining technology has recently been developed and commercialized.

Silicon microphones have the advantage of being less sensitive to moisture and heat, and are expected to replace electret condenser microphones due to their miniaturization and integration with signal processing circuits.

1 is a cross-sectional view showing a conventional silicon microphone package structure.

As shown in the drawing, a microphone structure 20 for converting a sound pressure change due to an acoustic signal into a vibration signal on a printed circuit board (PCB) 10 and an active signal for converting the vibration signal into an electrical signal The circuit part 30 is aligned and attached, and a frame 40 for protecting the microphone structure 20 and the active circuit part 30 is formed along the periphery of the printed circuit board 10, and the frame 40 is formed. Lid (50) having a negative pressure through-hole (55) is covered so that the external negative pressure flows through).

The printed circuit board 10, the microphone structure 20, and the active circuit unit 30 are electrically connected to each other by a bonding wire 60.

In addition, a passive circuit unit (not shown) including passive elements such as a resistor and a capacitor may be further formed to remove noise introduced into the microphone, apply a bias voltage, and match an input / output impedance.

The conventional silicon microphone packaging structure can make the size of the microphone structure 20 small, but the size of the active circuit portion 30 and the passive circuit portion (not shown) is large, which limits the overall size.

In addition, the bonding wire 60 formed for electrical connection between the printed circuit board 10, the microphone structure 20, the active circuit unit 30 and the passive circuit unit (not shown) also occupies a large space, and wire bonding (Wire bonding) Due to the bonding process, there is a problem of complicated manufacturing process.

An object of the present invention is to reduce the size of a silicon microphone package by forming a passive circuit portion made of passive elements in a substrate.

Another object of the present invention is to simplify and automate the manufacturing process by eliminating the wire bonding process in the manufacturing process of the silicon microphone package.

One preferred embodiment of the silicon microphone package for achieving the object of the present invention, there is a passive circuitry (Passive Circuitry) made of passive elements therein, a negative pressure through-hole to allow the external sound pressure (Sound Pressure) is induced A silicon microphone bonded to the substrate to be formed, a vibration plate vibrating by the external sound pressure on the substrate at the position where the negative pressure through-hole is formed, and bonded to the substrate, and electrically coupled with the vibration signal of the silicon microphone. Active circuitry for converting into a signal, a case formed along the outer periphery of the substrate, and formed on the lower surface of the substrate, and comprises a contact pad (Contact Pad) for electrical connection with the outside It is done.

Another preferred embodiment of the silicon microphone package for achieving the object of the present invention, the passive circuitry (Passive Circuitry) is built in the passive elements therein, and bonded to the substrate to be electrically connected to the passive circuitry; A silicon microphone, an active circuitry bonded to the substrate and converting the vibration signal of the silicon microphone into an electrical signal, and formed along the periphery of the substrate, A case in which a negative pressure through-hole is formed to induce an external sound pressure and a lower surface of the substrate is formed, and a contact pad for electrical connection with the outside is formed.

According to an embodiment of the present invention, there is provided a method of manufacturing a silicon microphone package, the method including preparing a substrate having passive circuitry formed of passive elements, and Mounting a silicon microphone and an active circuitry to be electrically connected, forming a case along the periphery of the substrate to protect the silicon microphone and the active circuitry from outside, and And forming a negative pressure through-hole through which the negative pressure is induced.

According to the present invention, the size of the silicon microphone package can be reduced by incorporating a passive circuit part made of passive elements such as a resistor, a capacitor, and an inductor inside the substrate.

The present invention removes the wire bonding process from the silicon microphone packaging process, aligns the silicon microphone and the active circuit part on the substrate, and then bonds the conductive bonding material such as solder through reflowing. Simplify and automate manufacturing processes to improve yield and productivity.

Hereinafter, the silicon microphone package of the present invention and a manufacturing method thereof will be described in detail with reference to FIGS. 2 to 5.

2 is a cross-sectional view showing an embodiment of a silicon microphone package of the present invention.

As shown in FIG. 2, the silicon microphone 110 and the active circuit unit 120 are bonded to each other by a solder 130 on the substrate 100, and the silicon microphone 110 is formed along the periphery of the substrate 100. A frame 140 protecting the 110 and the active circuit unit 120 is formed, and a lid 150 is adhered to the upper portion of the frame 140.

In addition, a passive circuit part including a resistor 161 and a capacitor 164 is formed in the substrate 100, and a contact pad for electrical connection with the outside is formed on a lower surface of the substrate 100. 170 is formed.

In addition, a negative pressure through hole 180 through which the external negative pressure may be induced is formed in the substrate 100 positioned below the silicon microphone 110.

The substrate 100 includes a passive circuit part including a resistor 161 and a capacitor 164 therein, which may be implemented using a low temperature co-fired ceramic (LTCC) technology.

Low-temperature co-fired ceramic (LTCC) technology uses a thick film (thickness from several tens to hundreds of micrometers) in the form of a tape casting method and uses a conductive paste to realize various circuit elements. Refers to a technique for manufacturing a stacked device.

In the low temperature co-fired ceramic (LTCC) technology, a conductive metal such as gold (Au) or silver (Ag), which has excellent conductivity and can be fired even in an oxidizing atmosphere, can be used to implement passive elements such as resistors, capacitors, and inductors. It is easy.

In the present invention, by using a low-temperature co-fired ceramic technology to form a passive circuit portion consisting of a resistor 161 and a capacitor 164 inside the substrate, it is possible to reduce the space occupied by the conventional passive circuit portion.

Meanwhile, the substrate 100 may be a multilayer printed circuit board as well as a low temperature co-fired ceramic substrate. In this case, the multilayer circuit printed circuit board includes a passive circuit unit including a resistor 161 and a capacitor 164.

However, it is preferable to use a low temperature co-fired ceramic substrate as the substrate 100. Since the ceramic is heat resistant, and the thermal expansion coefficient is similar to that of the silicon and metal materials constituting the silicon microphone 110 and the active circuit unit 120, This is because there is an advantage that problems such as deformation or weakening of bonding properties do not occur even in a high temperature process.

In addition, a contact pad 170 for connecting to an external device is formed on a lower surface of the low temperature cofired ceramic substrate 100, and the contact pad 170 is a via hole formed in the low temperature cofired ceramic substrate 100. Are electrically connected to the silicon microphone 110 and the active circuitry 120.

In addition, at least one negative pressure through hole 180 penetrating the substrate 100 is formed in the substrate 100 positioned below the silicon microphone 110.

In the present embodiment, since the silicon microphone 110 is bonded to the substrate 100 by flip-chip bonding, the diaphragm of the silicon microphone 110 faces the substrate 100.

Therefore, it is preferable that a negative pressure through hole 180 through which external air is introduced is formed in the region of the substrate 100 positioned under the silicon microphone 110.

The silicon microphone 110 converts a sound pressure change introduced from the outside into a vibration signal and is bonded to the substrate 100 by a flip chip bonding method.

That is, the silicon microphone 110 is turned upside down so that the diaphragm faces the substrate 100, the silicon microphone 110 is aligned with the solder 130 formed on the substrate 100, and then heat is applied to the solder 130. In addition, by reflow bonding, mechanical bonding and electrical connection with the substrate 100 are achieved.

As shown in FIG. 3, the silicon microphone 110 forms a back plate 113 on the silicon wafer 111 by using MEMS (MEMS) technology, and then closes the spacer 115. The diaphragm 117 is formed in the structure.

In this case, the spacer 115 is formed by stacking an insulating film on the silicon wafer 111, and then patterning and forming a diaphragm 117 made of a conductive material thereon.

The diaphragm 117 is a portion in which deformation or displacement occurs due to negative pressure introduced from the outside, such deformation or displacement of the diaphragm 117 causes a change in capacitance or a change in resistance or a current or voltage. .

The active circuit unit 120 converts the vibration signal generated from the silicon microphone 110 into an electrical signal, and is mechanically bonded to the substrate 100 through the solder 130 and electrically connected to the substrate 100.

That is, the active circuit unit 120 receives a change in capacitance, a change in resistance, a current, or a voltage signal generated from the silicon microphone 110 and converts it into a voltage or a current signal.

In addition, the active circuit unit 120 provides the converted signal to the outside by impedance matching, and converts an analog voltage or current signal into a digital signal and outputs the converted signal. To this end, the active circuit unit 120 is configured to include an analog amplifier or an analog-to-digital converter (ADC).

As described above, the present invention removes the wire bonding process from the silicon microphone packaging process, aligns the silicon microphone 110 and the active circuit unit 120 to the substrate 100, and then solders 130 and the like. By reflowing the conductive bonding material, the manufacturing process can be simplified and automated.

The frame 140 and the cover 150 are for protecting the silicon microphone 110 and the active circuit unit 120 from external physical shocks, and the frame 140 is formed along the periphery of the substrate 100. .

In this case, the frame 140 may be integrally formed with the substrate 100 or may be integrally formed with the cover 150 to be implemented as a case. In addition, the frame 140 may be formed separately from the substrate 100 and the cover 150.

4 is a cross-sectional view showing another embodiment of the silicon microphone package of the present invention.

As shown in FIG. 2, the silicon microphone 210 and the active circuit unit 220 are bonded to each other by a solder 230 on the substrate 200, and the silicon microphone 210 is formed along the periphery of the substrate 200. A frame 240 is formed to protect the 210 and the active circuit 220, and a lid 250 is adhered to the upper portion of the frame 240.

In addition, a passive circuit part including a resistor 261 and a capacitor 264 is formed inside the substrate 200, and a contact pad for electrical connection with the outside is formed on a lower surface of the substrate 200. 270 is formed.

In addition, a sound pressure through hole 280 through which the external sound pressure may be induced is formed in the cover 250 positioned on the silicon microphone 210.

In this embodiment, since the silicon microphone 210 is not inverted and bonded to the substrate 200, the diaphragm of the silicon microphone 210 faces the cover 250, and thus the cover 250 rather than the substrate 100. Negative pressure through hole 280 is formed.

In the present embodiment, the silicon microphone 210 penetrates the silicon microphone 210 positioned above the solder 230 for electrical connection between the diaphragm of the silicon microphone 210 and the substrate 200. The via hole 215 filled with the conductive material is formed.

5 is a flowchart showing an embodiment of a method of manufacturing a silicon microphone package of the present invention.

As shown in the drawing, first, a substrate in which a passive circuit part made of passive elements such as a resistor, an inductor, and a capacitor is prepared is prepared (S 100).

The substrate may be a low temperature cofired ceramic (LTCC) substrate or a multilayer printed circuit board, but it is particularly preferable to use a low temperature cofired ceramic substrate.

The substrate may further be provided with a negative pressure through-hole through which external air may be introduced, depending on the form of bonding of the silicon microphone to be described later.

Next, the silicon microphone and the active circuit unit is mounted on the substrate (S 110).

That is, a solder is formed on the pad formed on the substrate, the silicon microphone and the active circuit unit are aligned with the solder, and then heat is applied to the solder to reflow bond. In this case, the pad formed on the substrate is formed at a position electrically connected to the passive elements inside the substrate.

On the other hand, the position where the negative pressure through-hole is formed depends on the bonding form of the silicon microphone.

That is, when the silicon microphone is turned upside down and bonded by flip chip bonding, since the diaphragm of the silicon microphone faces the substrate, a negative pressure through hole must be formed in the substrate, and when the silicon microphone is bonded by soldering without inverting the silicon microphone, the silicon microphone Since the diaphragm of the toward the cover to be described later to form a negative pressure through-hole in the cover.

Subsequently, a frame is formed along the periphery of the substrate (S 120), and a cover is attached to the upper portion of the substrate to protect the silicon microphone and the active circuit part from external impact (S 130). At this time, the frame and the cover may be integrated into a case.

Although the present invention has been described in detail with reference to exemplary embodiments above, those skilled in the art to which the present invention pertains can make various modifications to the above-described embodiments without departing from the scope of the present invention. I will understand.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

1 is a cross-sectional view showing a conventional silicon microphone package structure.

Figure 2 is a cross-sectional view showing one embodiment of a silicon microphone package of the present invention.

3 is a cross-sectional view showing the structure of a silicon microphone;

Figure 4 is a cross-sectional view showing another embodiment of the silicon microphone package of the present invention.

Figure 5 is a flow chart showing an embodiment of a method of manufacturing a silicon microphone package of the present invention.

Explanation of symbols on the main parts of the drawings

100, 200: substrate 110, 210: silicon microphone

120, 220: active circuit 130, 230: solder

140, 240: frame 150, 250: cover

161, 261: resistors 164, 264: capacitors

170, 270: contact pads 180, 280: negative pressure through holes

Claims (9)

A substrate having a passive circuitry made of passive elements therein and having a negative pressure through hole formed therein so as to induce an external sound pressure; A silicon microphone bonded on the substrate at the position where the negative pressure through hole is formed such that a diaphragm vibrating by the external negative pressure faces the substrate; An active circuitry bonded to the substrate and converting a vibration signal of the silicon microphone into an electrical signal; A case formed along the periphery of the substrate; And The silicon microphone package is formed on the lower surface of the substrate, and comprises a contact pad for electrical connection with the outside. The method of claim 1, The silicon microphone package is characterized in that the bonding by flip-chip bonding (Flip-Chip Bonding). A substrate having a passive circuitry made of passive elements therein; A silicon microphone bonded on the substrate to be electrically connected with the passive circuit portion; An active circuitry bonded to the substrate and converting a vibration signal of the silicon microphone into an electrical signal; A case formed along an outer periphery of the substrate and having a negative pressure through hole formed thereon to induce an external sound pressure to a vibration plate of the silicon microphone; And The silicon microphone package is formed on the lower surface of the substrate, and comprises a contact pad for electrical connection with the outside. The method of claim 3, And the silicon microphone is bonded by a solder formed on the substrate. The method of claim 4, wherein The silicon microphone, And a via hole filled with a conductive material through a silicon microphone on the solder for electrical connection between the diaphragm and the substrate. The method according to claim 1 or 3, The substrate is a silicon microphone package, characterized in that the low temperature co-fired ceramic (LTCC) substrate. The method according to claim 1 or 3, The case, The silicon microphone package, characterized in that consisting of a frame (Frame) formed along the outer periphery of the substrate, and a lid (Lid) bonded to the upper portion of the frame. Preparing a substrate having a passive circuitry including passive elements; Mounting a silicon microphone and an active circuitry on the substrate to be electrically connected to the passive circuitry; Forming a case along the periphery of the substrate to protect the silicon microphone and active circuitry from the outside; And And forming a negative pressure through hole in the silicon microphone to induce external sound pressure. The method of claim 8, The substrate is a low temperature co-fired ceramic (LTCC) substrate manufacturing method of a silicon microphone package, characterized in that.

Images