KR100650280B1 - Silicon based condenser microphone - Google Patents

Abstract

A silicon condenser microphone having a sound hole on a substrate is provided to reduce a manufacturing cost and a processing cost by adhering a metal case to the substrate with an adhesive after laser welding. A metal case(110) has a closed bottom plane. A sound hole is formed on a substrate(120) for receiving an outer sound. A sealing terminal is formed to seal the sound hole with soldering for preventing a sound wave from being distorted between a main PCB and a microphone. A specific type semiconductor chip having a MEMS microphone chip, a voltage bumper, and a buffer IC is mounted on the substrate(120). A connection pattern is formed to be connected to the metal case(110) on the substrate(120). A fixing unit(130) fixes the metal case(110) on the substrate(120). An adhesive(140) is spread on a connection plane of the substrate(120) and the metal case(110) fixed by the fixing unit(130). The adhesive(140) connects the metal case(110) to the substrate(120).

Description

Silicon Condenser Microphone with Sound Hole on Substrate {SILICON BASED CONDENSER MICROPHONE}

1 is an exploded perspective view of a first embodiment of a silicon condenser microphone in which a sound hole is formed in a substrate according to the present invention;

2 is a side cross-sectional view of a first embodiment of a silicon condenser microphone in which a sound hole is formed in a substrate according to the present invention;

3 is an example showing a MEMS chip structure of a silicon condenser microphone according to the present invention;

4 is a circuit diagram of a silicon condenser microphone according to the present invention;

5 is a flowchart illustrating a packaging procedure of a silicon condenser microphone according to the present invention;

6 is an exploded perspective view of a second embodiment according to the present invention;

7 is an exploded perspective view of a third embodiment according to the present invention;

8 is an exploded perspective view of a fourth embodiment according to the present invention;

9 is a side cross-sectional view of an example in which a silicon condenser microphone in which a sound hole is formed in a substrate is mounted on a main PCB according to the present invention;

FIG. 10 is an exploded perspective view of a case in which a sound hole is formed in a substrate in which a MEMS chip is attached as a modification of the first embodiment shown in FIG. 1;

FIG. 11 is a side sectional view of the microphone of the first embodiment shown in FIG. 10;

12 is a side cross-sectional view of a fifth embodiment in which a connection terminal is formed on a component surface of a substrate and an acoustic hole is formed in a substrate at which a MEMS chip is attached according to the present invention;

FIG. 13 illustrates a concept of packaging a condenser microphone in the related art. FIG.

* Explanation of symbols for main parts of the drawings

10: MEMS chip 20: ASIC chip for special purpose

100,200: microphone 110,210: case

120a and 220a: sound hole 120 and 220: substrate

121,221: connection pattern 123,125: connection terminal

124: through hole 130: available contact

140: adhesive 300: main PCB

120b, 302: sealing terminal 304: connection pad

310: soldering portion

The present invention relates to a condenser microphone, and more particularly, to a silicon condenser microphone in which an acoustic hole is formed in a substrate.

In general, a condenser microphone widely used in a mobile communication terminal or an audio device includes a voltage bias element, a diaphragm / backplate pair forming a capacitor C that changes in response to sound pressure, and a buffer for output signal. It consists of a field effect transistor (JFET). The conventional condenser microphone inserts a diaphragm, spacer ring, insulation ring, back plate, and conduction ring in one case, and finally inserts a PCB with circuit components and bends the end of the case to the PCB side. It consisted of an assembly.

However, the curling method of bending the end of the case while applying pressure to the PCB side has a problem that affects the shape or acoustic characteristics of the final product according to the pressure during the process and the tolerance of the parts. That is, when the pressing force is insufficient in the currying process, the sound pressure leaks between the case and the PCB, and the sound quality deteriorates. When the pressing force is excessive during the currying, the surface to be cut is torn or the internal parts are deformed, resulting in acoustic There was a problem that the characteristics are distorted.

In order to solve this problem, the case joint structure of the condenser microphone and its manufacturing method have been disclosed in Korean Patent Laid-Open Publication No. 10-2004-0072099.

As shown in FIG. 13, a conventional condenser microphone structure including a case 30, a diaphragm, a spacer, a bipolar plate, an injection molded product, a connection ring, and a substrate 40 is disclosed. The open end of the case 30 is bent outward to form a connecting piece 31 in an annular shape along the end of the case 30, and on the substrate 40 of the surface opposite to the connecting piece 31 of the case 30. After forming the welding area 41 by plating a conductive metal on the edge, each component is sequentially installed inside the case 30, and the joining piece 31 of the case and the welding area 41 of the substrate are interviewed. In order to pressurize the case and the substrate to two electrodes (+ electrode,-electrode) and pressurize it instantaneously to supply electricity, the welding region 41 formed on the substrate and the connecting piece 32 of the case are melted. To bond the connecting piece 31 and the welding area 41 of the substrate It is.

However, in the case where the welding area of the case and the welding area of the substrate is entirely welded, deformation and stress are generated in the components due to the heat generated during welding, and it is difficult to install and operate the electrodes, which makes the welding construction difficult. have.

On the other hand, as a technology recently used for the integration of micro devices, there is a semiconductor processing technology using micromachining. This technology, called MEMS (Micro Electro Mechanical System), can produce micro sensors, actuators, and electromechanical structures in micrometers using micromachining technology using semiconductor processing, especially integrated circuit technology. MEMS chip microphones manufactured using this micromachining technology are capable of miniaturization, high performance, multifunction, integration through ultra-precision micromachining, and have the advantage of improving stability and reliability.

Therefore, a new packaging technology for efficiently bonding a case and a substrate is required not only for a conventional condenser microphone but also a silicon condenser microphone using MEMS technology.

The present invention has been proposed to solve the problems of the prior art as described above, by fixing the end of the metal case to the substrate on which the MEMS (MEMS) microphone parts are seated and formed with a laser, and then bonded with an adhesive It is to provide a silicon condenser microphone that prevents the occurrence of defects, improves the bonding strength and is resistant to external noise such as electromagnetic noise.

In order to achieve the above object, the microphone of the present invention includes a metal case with a closed bottom surface and an acoustic hole for inputting external sound, and around the acoustic hole in the space between the main PCB and the microphone. In order to prevent distortion, a sealing terminal is formed to seal the sound hole by soldering, and a MEMS microphone chip and a special purpose semiconductor (ASIC) chip including a voltage pump and a buffer IC are mounted. A substrate on which a connection pattern for joining the metal case is formed; Fixing means for fixing the metal case to the substrate; And an adhesive applied around the entire bonding surface of the metal case and the substrate fixed by the fixing means to bond the metal case and the substrate.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]

1 is an exploded perspective view of a first embodiment of a silicon condenser microphone in which a sound hole is formed in a substrate according to the present invention, and FIG. 2 is a side cross-sectional view of the silicon condenser microphone shown in FIG.

1 and 2, the MEMS chip 10 and the ASIC chip 20 are mounted on a cylindrical metal case 110 having a closed upper surface, and the sound hole 120a is mounted. In this example, the metal case 110 is fixed to the substrate 120 by welding with the connection pattern 121 of the formed substrate 120 using a laser, and then the entire circumference of the connection surface is bonded with the adhesive 140. Here, the adhesive 140 may be a conductive epoxy, non-conductive epoxy, silver paste, silicon, urethane, acrylic, cream solder, and the like.

1 and 2, a sound hole 120a for introducing external sound is formed near the center of the substrate 120, and a MEMS chip 10 and an ASIC chip 20 are disposed around the sound hole 120a. ) Is mounted, and a circular connection pattern 121 is formed at a portion in contact with the metal case 110. Although not shown in the drawings, if necessary, a capacitor or a resistor for electromagnetic shielding or ESD shielding may be mounted together.

Since the size of the substrate 120 is larger than that of the metal case 110, a connection pad or a connection terminal for connecting to an external device can be freely disposed on a wide substrate surface, and the connection pattern 121 is a general PCB fabrication process. After raising the copper foil through, it is formed by plating nickel (Ni) or gold (Au). In this case, various substrates such as a PCB substrate, a ceramic substrate, an FPCB substrate, and a metal PCB substrate may be used as the substrate 120.

The metal case 110 has a cylindrical shape in which one surface is blocked and a connection surface with the substrate 120 is opened to mount chip components therein, and external sound is introduced through the acoustic hole 120a of the substrate. Therefore, the bottom surface of the metal case 110 is blocked. The metal case 110 may be made of brass, copper, stainless steel, aluminum, nickel alloy, or the like, and may be used by gold or silver plating, and the metal case may have various shapes such as round or square.

After the metal case 110 is aligned with the connection pattern 121 of the substrate 120, the case 110 is welded with a laser using a laser processing machine (not shown) to attach the case 110 to the substrate 120. After fixing to, the adhesive 140 is applied around the entire connecting surface to complete the microphone package. Here, 'welding' means not welding the entire surface where the case 110 and the substrate 120 meet, but at least one or more places (this is called an available welding point) to fix the case 110 and the substrate 120. Preferably two to four spot welding). In this way, the junction formed between the case 110 and the substrate 120 by tack welding is referred to as a tack welding point 130. The case 110 is fixed to the substrate 120 by the tack welding point 130. When the case 110 is adhered to the case 120 with the adhesive 140 or the case 110 does not move in the curing process, the bonding may be performed at the correct position. In addition, the connection pattern 121 is connected to the ground terminal 125, and when the metal case 110 is bonded thereto, there is an advantage that it is easy to remove the noise by blocking the inflow of external noise.

As shown in FIG. 2, the microphone assembly 100 having the packaging is completed, and the adhesive pattern 121 of the substrate 120 and the metal case 110 are fixed to the soluble welding point 130 by a laser, and then adhesive. Bonded by 140, the space 150 between the metal case 110 and the substrate 120 serves as an acoustic chamber.

In addition, an acoustic hole 120a for inputting external sound is formed in the substrate 120, and around the bottom acoustic hole of the substrate 120, distortion of sound waves is spaced in a space between the main PCB (300 in FIG. 9) and the microphone. In order to prevent the sealing terminal 120b is formed to seal the sound hole 120a by soldering. In this case, at least two or more connection terminals 123 and 125 for connecting with an external device may be formed, and each connection terminal 123 and 125 may be electrically connected to the chip component surface through the through hole 124. . In particular, when the connection terminals 123 and 125 are formed to the periphery of the substrate 120 in the embodiment of the present invention, the rework operation can be easily performed by approaching the electric iron through the exposed surface.

An example of mounting the microphone of the present invention on the main PCB 300 is as shown in FIG. 9.

Referring to FIG. 9, a main sound hole 300a for introducing external sound is formed in the main PCB 300 of the product on which the microphone is to be mounted, and the main PCB 300 is surrounded by the main sound hole 300a. In order to prevent distortion of sound waves in the space between the microphone and the microphone, a sealing terminal 302 is formed to seal the sound hole 300a by soldering and is connected to the connection terminals 123 and 125 of the microphone. Pad 304 is formed. When the microphone according to the present invention is connected to the main PCB 300 by soldering 310, the external sound is introduced through the main sound hole 300a of the main PCB 300, and then, by the sealing terminal 302. Passed through the sealed region is input into the microphone through the sound hole (120a) of the microphone substrate 120.

As shown in FIG. 3, the MEMS chip 10 forms the back plate 13 on the silicon wafer 14 using MEMS technology, and then the vibration membrane 11 is disposed between the spacers 12. This structure is formed. Therefore, the sound introduced into the microphone vibrates the vibrating membrane 11 of the MEMS chip to change the capacitance formed between the vibrating membrane 11 and the back plate 13 to convert the sound flowing from the outside into an electrical signal. .

The special purpose semiconductor (ASIC) chip 20 is connected to the MEMS chip 10 to process electrical signals. As shown in FIG. 4, the MEMS chip 10 provides a voltage to operate as a condenser microphone. It is composed of a buffer IC 24 for amplifying or impedance matching the electrical sound signal sensed through the voltage pump 22 and the MEMS chip 10 to provide to the outside through the connection terminal. Here, the voltage pump 22 is a DC-DC converter, and the buffer IC 24 may use an analog amplifier, an analog-to-digital converter (ADC), or the like. In the circuit diagram of FIG. 4, the capacitor symbol "C0" represents an electrical equivalent circuit for the MEMS chip 10, and the MEMS microphone package 100 is connected to an external device through three connection terminals Vdd, GND, and Output. It can be seen that.

In the exemplary embodiment of the present invention, the fixing of the case 110 to the substrate 120 is described only by the soluble welding using a laser, but other methods such as soldering and punching may be used.

5 is a flowchart illustrating a packaging procedure of a silicon condenser microphone according to the present invention.

According to the present invention, a method of packaging a silicon condenser microphone is shown in FIG. 5, in which the step of inserting the substrate 120 (S1), the MEMS component 10, and the special purpose semiconductor (ASIC) chip 20 are performed. Step (S2) of mounting on the substrate 120, the step (S3) of inserting the metal case 110, the step (S4) of aligning the case 110 to the connection pattern 121 of the substrate, the case 110 Fixing the connection pattern 121 of the end portion and the substrate by welding or the like (S5), after fixing the case 110 to the substrate 120, the substrate 120 and the case 110 meet with the adhesive 140. Applying the entire circumference of the portion is a step (S6) of bonding the case 110 and the substrate 120, and curing the adhesive 140 (S7).

In this case, various substrates such as a PCB substrate, a ceramic substrate, an FPCB substrate, and a metal PCB substrate may be used as the substrate 120, and a connection pattern 121 for connecting to the metal case 110 is formed on the substrate 120. have.

In addition, the material of the metal case 110 may be brass, copper, stainless steel, aluminum, nickel alloy, and the like, and may be used by gold or silver plating, and the shape of the metal case 110 may be round or square. Do.

In step 5 (S5) of fixing the metal case 110 to the substrate 120, welding or punching may be performed by laser welding or soldering, and as the adhesive 140, conductive or non-conductive epoxy may be used. After bonding to the adhesive 140, the adhesive 140 is cured by natural curing, ultraviolet curing, thermal curing, or the like to complete the manufacture of the microphone.

According to the packaging method of the present invention as described above, the metal case 110 is welded and fixed to the substrate 120 by a laser, and then bonded and cured by an adhesive 140 to enhance bonding strength (electrical connection force and sealing performance), thereby improving sound quality. In addition, it is strong in external noise, in particular, there is an advantage that can significantly reduce the overall manufacturing cost by reducing the occurrence of defects and the process cost.

Meanwhile, in the first embodiment of FIG. 1, the acoustic hole is formed on the substrate where the component is not mounted. However, as shown in FIGS. 10 and 11, the MEMS chip 10 is attached as a modified example. The acoustic hole 120a may be formed in the substrate of the substrate. 10 and 11, external sound introduced through the acoustic hole 120a of the substrate flows directly into the MEMS chip 10 to vibrate the diaphragm.

Second Embodiment

6 is an exploded perspective view of a second embodiment according to the present invention. The second embodiment of the present invention is a rectangular cylindrical metal case 210 is welded to the substrate 220 with a laser and then bonded with an adhesive 140. . In the second embodiment, all four welding points 130 are formed by welding one point to each side of the rectangular case 210.

Referring to FIG. 6, an acoustic hole 220a for introducing external sound is formed in the substrate 220, and a MEMS chip 10 and an ASIC chip 20 are mounted around the acoustic hole 220a. A rectangular connection pattern 221 is formed at a portion in contact with the metal case 210. The connection pattern 221 is formed of a copper foil film by a conventional PCB pattern technique, and the distortion of sound waves in the space between the main PCB (300 in FIG. 9) and the microphone is disposed around the bottom acoustic hole 220a of the substrate 220. In order to prevent the sealing terminal 120b for sealing the sound hole by soldering (Hole sealing) is formed.

The metal case 210 has a rectangular cylindrical shape in which a surface which is connected to the PCB substrate 220 is opened, and since external sound is introduced through the acoustic hole 220a of the substrate, the bottom surface of the case is blocked.

After aligning the metal case 210 with the connection pattern 221 of the substrate 220, the case 210 is fixed by welding the soluble welding point 130 with a laser using a laser processing machine (not shown). The adhesive 140 is applied around the entire surface and then cured to complete the microphone packaging. Here, the connection pattern 221 is connected to the ground terminal, when the metal case 210 is welded there, there is an advantage that it is easy to remove the noise by blocking the inflow of external noise.

Since the microphone assembly is packaged as described above is the same as shown in Figure 2, further description will be omitted to avoid repetition.

Third Embodiment

Figure 7 is an exploded perspective view of a third embodiment according to the present invention, the third embodiment of the present invention is a cylindrical metal case (110 ') and a PCB substrate having a wing 116 protruding in the shape of the letter "b" The soluble welding point 130 of 120 is laser-welded and fixed to each other, and then the entire circumference of the adhesive surface is bonded with the adhesive 140.

Referring to FIG. 7, an acoustic hole 120a for introducing external sound is formed in the substrate 120, a MEMS chip 10 and an ASIC chip 20 are mounted, and a metal case 110 ′. A circular connection pattern 121 is formed in the contact portion. Although not shown in the drawing, around the bottom acoustic hole 120a of the PCB substrate 120, the acoustic hole 120a is sealed by soldering to prevent distortion of sound waves in the space between the main PCB (300 in FIG. 9) and the microphone. A sealing terminal 120b for hole sealing is formed. Since the size of the substrate 120 is larger than that of a metal case, a connection pad or a connection terminal for connecting to an external device can be freely disposed on a wide PCB surface, and the connection pattern is formed by raising a copper foil through a general PCB manufacturing process. Nickel (Ni) or gold (Au) plating is preferable. In the third embodiment of the present invention, the connection pattern 121 is preferably wider than the first embodiment corresponding to the wing 116 formed in the metal case.

The metal case 110 ′ of the third embodiment has a cylindrical shape in which a connection surface is opened with the PCB substrate 120, and external sound is introduced through the acoustic hole 120 a of the PCB substrate, so that the bottom surface of the case is blocked, and the case body. An end surface of the 114 is formed with a wing 116 protruding outward.

After arranging the end blades 116 of the metal case 110 'to the connection pattern 121 of the PCB substrate, the case 110' is welded with a laser using a laser processing machine (not shown) and the case 110 'is attached to the substrate 120. After fixing to the adhesive 140 to complete the packaging.

[Example 4]

8 is an exploded perspective view of a fourth embodiment according to the present invention. The fourth embodiment of the present invention is a substrate having a rectangular cylindrical metal case 210 'formed with a wing 216 protruding at the end. After welding and fixing to the laser at 220, it is bonded with an adhesive.

Referring to FIG. 8, an acoustic hole 220a for introducing external sound is formed in the PCB 220, a MEMS chip 10 and an ASIC chip 20 are mounted, and a metal case 210 ′. A rectangular connection pattern 221 is formed at a portion in contact with the contact surface. Although not shown in the drawing, around the bottom acoustic hole 220a of the PCB substrate 220, the acoustic hole 220a is sealed by soldering to prevent distortion of sound waves in the space between the main PCB (300 in FIG. 9) and the microphone. A sealing terminal for hole sealing is formed. Since the size of the PCB 220 is larger than that of the metal case 210 ', a connection pad or a connection terminal for connecting to an external device can be freely disposed on a wide PCB surface, and the connection pattern 221 is a general PCB. It is preferable to plate nickel (Ni) or gold (Au) after raising copper foil through a manufacturing process. In the fourth embodiment of the present invention, the connection pattern 221 is preferably wider than the second embodiment corresponding to the wing 216 formed at the end of the body 214 of the metal case 210 '.

The metal case 210 'is a rectangular cylindrical shape in which a connection surface of the PCB substrate 220 is opened, and external sound is introduced through the acoustic hole 220a of the PCB, so that the bottom surface of the case 210' is blocked. An end surface of the body 214 is formed with wings 216 protruding outward.

After aligning the end blades 216 of the metal case with the connection pattern 221 of the substrate, the case 210 ′ is temporarily welded with a laser using a laser processor (not shown) to form the case 210 ′ on the substrate 120. ), The adhesive 140 is applied around the entire adhesive surface of the case 210 'and the substrate 120, and then cured to complete the microphone packaging.

[Example 5]

12 is a side cross-sectional view of a fifth embodiment in which a connection terminal is formed on a component surface of a substrate and an acoustic hole is formed in a substrate at which a MEMS chip is attached in accordance with the present invention.

As shown in FIG. 12, the silicon condenser microphone according to the present invention has a substrate having a cylindrical hole with a closed bottom surface that is wider than the metal case 110, and has an acoustic hole 120a for introducing external sound. 120 is attached to the adhesive 140, and a connection terminal 122 for connecting to the connection pad 320 of the main PCB 230 of the product in which the microphone is to be used is formed on the component surface 120b of the substrate.

In addition, the main PCB 310 of the product on which the silicon condenser microphone according to the present invention is to be mounted has a circular insertion hole 310a so that the case 110 of the directional silicon condenser microphone can be mounted, and the substrate 120 of the microphone is formed. The connection pad 320 is formed to correspond to the connection terminal 122 formed at

As shown in FIG. 12, the entire structure in which the silicon condenser microphone is mounted on the main PCB 310 is inserted into the main PCB 310 by the metal case 110 protruding from the center portion of the board component surface 120b. In addition to being inserted into the hole 310a, the connection pad 320 of the main PCB and the connection terminal 122 of the microphone are connected by the soldering 330.

Therefore, according to the mounting method of the present invention, since the case 110 portion protruding from the substrate of the microphone is inserted into the insertion hole 310a formed in the main PCB 310, the overall height after mounting is on the opposite side of the component surface in the conventional microphone. The connection terminal is formed and lower than the overall height when it is mounted on the main PCB so that the component mounting space of the product can be used efficiently.

As described above, the present invention can receive the external sound through the acoustic hole formed on the substrate, and the metal case is welded to the substrate with a laser and then bonded with an adhesive to increase the bonding strength, thereby improving mechanical robustness, and external noise. It is also strong and in particular has the advantage of significantly reducing the overall manufacturing cost by reducing the process cost.

In addition, by eliminating the curling process, which is a process of joining the metal case and the substrate in the conventional microphone manufacturing process, by directly welding the metal case to the substrate on which the component for the condenser microphone is mounted, the electrical conduction characteristics between the case and the substrate can be improved. The sound characteristics can be improved by sealing the sound pressure from the outside.

In addition, since the shape of the substrate is not limited by the case, it is possible to freely design the PCB (PCB) used in the microphone, and thus various types of terminals can be formed, and work can be performed without physical force applied during curling as in the prior art. Since it is possible to apply a thinner substrate (PCB), it is possible to lower the height of the product when using this thin substrate (PCB) can be manufactured a thinner microphone.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand that you can.

Claims (7)

Metal case with blocked bottom surface; A sound hole for inputting external sound is formed, and a sealing terminal is formed around the sound hole to seal the sound hole by soldering to prevent distortion of sound waves in the space between the main PCB and the microphone. (MEMS) a substrate on which a microphone chip, a special purpose semiconductor (ASIC) chip in which a voltage pump and a buffer IC (IC) are embedded, is mounted, and a connection pattern for bonding to the metal case is formed; Fixing means for fixing the metal case to the substrate; And And an adhesive applied around the entire bonding surface of the metal case and the substrate fixed by the fixing means to bond the metal case and the substrate. The method of claim 1, wherein the fixing means, A silicon condenser microphone, wherein the silicon condenser microphone is a soluble welding point formed by laser welding or welding. The method of claim 1, wherein the adhesive Silicon condenser microphone, characterized in that any one of conductive epoxy, non-conductive epoxy, silver paste, silicon, urethane, acrylic, cream solder. The method of claim 1, wherein the metal case A silicon condenser microphone, characterized by a cylindrical or square cylinder type. 5. The end of the metal case of claim 4, wherein Silicon condenser microphone, characterized in that the straight or bent outward form the blade. The method of claim 1, wherein the substrate Silicon condenser microphone, characterized in that any one of the PCB substrate, ceramic substrate, FPCB substrate, metal PCB substrate. The method of claim 1, wherein the sound hole, Silicon condenser microphone, characterized in that formed on the substrate of the position where the MEMS chip is attached.

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