CN1813490B - Package structure of silicon capacitor microphone and fabrication method thereof - Google Patents

Abstract

The present invention relates to a packaging of a silicon condenser microphone and method for manufacturing the same. The packaging structure of a silicon condenser microphone of the present invention comprises a substrate having an upper surface for disposing the silicon condenser microphone and a circuit unit thereon, the substrate having a back chamber therein, the substrate including an air hole for an air to pass through between the upper surface for disposing the silicon condenser microphone and the back chamber; and a casing covering the silicon condenser microphone and the circuit unit disposed on the upper surface of the substrate for protection thereof. The method for manufacturing a packaging structure of a silicon condenser microphone of the present invention comprises steps of: (a) forming a substrate having a back chamber therein, wherein the substrate includes an air hole for an air to pass through between an upper surface of the substrate, the air hole disposed at a portion of the upper surface where the silicon condenser microphone and a circuit unit is to be disposed; (b) bonding the silicon condenser microphone and the circuit unit to the upper surface of the substrate; and (c) covering the silicon condenser microphone and the circuit unit with a casing to protect the silicon condenser microphone and the circuit unit.

Description

Packaging structure and manufacturing method of silicon condenser microphone

technical field

The present invention relates to a microphone, and in particular to a packaging structure of a silicon condenser microphone and a manufacturing method thereof.

Background technique

In general, a microphone refers to a converter used to convert sound energy into electrical energy. A condenser microphone as one of the microphones is a microphone employing the principle of a capacitor in which two electrode plates are opposed to each other. When one of the electrode plates is used as a vibrating plate, the vibrating plate vibrates according to the sound to change the capacitance of the capacitor, thereby changing the accumulated charge. Therefore, electric current flows according to the change of sound.

Among condenser microphones, an electret condenser microphone is the most well-known, and the electret condenser microphone is characterized in that an electret, which is a material including semi-permanent charges, is used instead of a bias to form an electrostatic charge. field. The electret is formed by thermally bonding or bonding a polymer film to a conductive backplane.

However, polymer films are limited in recent developments in which features are smaller than one nanometer in size. In addition, since the electret using the polymer film is sensitive to temperature or humidity, the characteristics may decrease, thereby deteriorating the performance of the microphone itself. In addition, a vibration plate using a polymer film is too thick, resulting in insufficient vibration characteristics and poor sensitivity.

Therefore, in order to improve these characteristics, a silicon microphone with improved temperature and vibration characteristics that allows batch processing in semiconductor manufacturing processes is discussed. US Patent Application No. US2002/0102004 discloses a microphone package named "Miniature Silicon Condenser Microphone And Method For Producing Same" (Miniature Silicon Condenser Microphone And Method For Producing Same).

FIG. 1 is a cross-sectional view showing a package structure of a silicon condenser microphone disclosed in US Patent Application No. US2002/0102004.

Referring to FIG. 1 , a silicon condenser microphone 12 and a circuit unit 16 are disposed on a substrate 14 having a recessed area 18 . The silicon condenser microphone 12 is arranged on the recessed area 18 . A case 20 is arranged for stability. An opening 24 is formed in the housing 20 and then covered with a sealant 26 . The sound pressure is transmitted inwardly to the silicon condenser microphone 12 through the gap between the opening 24 and the sealant 26 .

In general, in order to increase the sensitivity of a microphone, it is necessary to provide an environment in which the vibration plate responds sensitively to sound. For this reason, the size of the back chamber, which is the space between the back plate and the base, should be sufficient so that the pressure in the back chamber can be ignored even when the vibrating plate vibrates.

According to the prior art described above, the rear chamber is obtained by forming a recessed area 18 in order to increase the sensitivity of the microphone. However, since the substrate 14 is usually manufactured using FR-4 (flame retardant compound 4) as an epoxy resin, during the subsequent high-temperature heat treatment (for example, reflow treatment), due to the poor heat resistance characteristics of epoxy resin Distortion may occur due to heat.

In addition, since the thermal expansion coefficient difference between the base 14 made of epoxy resin and the silicon condenser microphone 12 and the circuit unit 16 arranged on the base is large, bonding characteristics are degraded during high-temperature heat treatment, thereby generating bonding defects.

In addition, since the recessed region 18 is formed by etching a substrate having a specific shape, the increase in size of the rear chamber is limited by the increase in size of the recessed region.

Contents of the invention

An object of the present invention is to provide the package structure of silicon condenser microphone and its manufacture method, wherein the substrate that is arranged with silicon condenser microphone and circuit unit is made of heat-resistant ceramic material, and this ceramic material has the thermal expansion coefficient with silicon condenser microphone and circuit unit Similar thermal expansion coefficients to prevent deformation and decrease in bonding properties due to heat during high temperature heat treatment.

According to an embodiment of the present invention, another object of the present invention is to provide a package structure of a silicon condenser microphone and a manufacturing method thereof, wherein the base is formed by combining a plurality of chamber plates so that the shape can be changed in various ways and A space for a back chamber may be formed.

According to an embodiment of the present invention, another object of the present invention is to provide a package structure of a silicon condenser microphone and a manufacturing method thereof, wherein a pillar is formed in the rear chamber to prevent the chamber plate from collapsing due to the rear chamber.

According to an embodiment of the present invention, another object of the present invention is to provide a packaging structure of a silicon capacitor microphone and a manufacturing method thereof, wherein a protrusion is included on the surface (or upper part) of the substrate to prevent the silicon capacitor from being used for bonding. Adhesive or mounting epoxy for the microphone and circuit unit spread into undesired areas.

In order to achieve the above object of the present invention, according to an embodiment of the present invention, a packaging structure of a silicon condenser microphone is provided, the packaging structure includes: a substrate, which has an upper surface, and a silicon condenser microphone and a silicon condenser microphone are arranged on the upper surface a circuit unit, the substrate having therein a rear chamber formed under the silicon condenser microphone and the circuit unit, the substrate including air holes for passing air through an upper surface for arranging the silicon condenser microphone and between the rear chamber; and a case covering the silicon condenser microphone and the circuit unit arranged on the upper surface of the base for protecting them.

Preferably, the height of the portion of the upper surface other than the portion covered by the silicon condenser microphone and the circuit unit is higher than the height of the portion of the upper surface covered by the silicon condenser microphone and the circuit unit , and wherein the space below the portion of the upper surface other than the portion covered by the silicon condenser microphone and the circuit unit is used as a part of the rear chamber.

In order to achieve the above object of the present invention, according to an embodiment of the present invention, a method for manufacturing a packaging structure of a silicon condenser microphone is provided, the method includes the following steps: (a) forming a substrate, in which there is a rear a chamber, the rear chamber is formed under the silicon condenser microphone and the circuit unit, wherein the substrate includes an air hole for passing air between the upper surface of the substrate and the rear chamber, the air hole is arranged on the upper surface (b) combining the silicon condenser microphone and the circuit unit on the upper surface of the substrate; and (c) covering the silicon condenser microphone and the circuit unit with a housing The circuit unit is used to protect the silicon condenser microphone and the circuit unit.

As described above, according to the silicon condenser microphone and its manufacturing method, the substrate on which the silicon condenser microphone and the circuit unit are arranged is made of a heat-resistant ceramic material having a thermal expansion coefficient close to that of the silicon condenser microphone and the circuit unit , to prevent deformation and decrease in bonding properties due to heat during high-temperature heat treatment. Specifically, since the ceramic material has high heat-resistant characteristics, product damage due to an increase in processing temperature can be reduced.

In addition, the base is formed by combining a plurality of chamber plates, so that the shape can be changed in various ways and a space for the rear chamber can be formed. Specifically, when the height of the portion of the substrate exposed by the silicon condenser microphone and the circuit unit is increased along its edge portion and the inner space is used as the rear chamber, the size of the rear chamber can be maximized to improve the sensitivity of the microphone. In addition, when the height of the base is increased to that of the case, the case can be manufactured to have a flat structure, thereby reducing manufacturing costs.

According to the packaging structure of the silicon condenser microphone and the manufacturing method thereof of the present invention, a pillar is formed in the rear chamber to prevent the chamber plate from collapsing due to the rear chamber. Therefore, the space for the rear chamber is enlarged while maintaining stability.

According to the packaging structure of the silicon condenser microphone and its manufacturing method of the present invention, a protrusion is included on the surface (or upper part) of the substrate to prevent the adhesive or fixing epoxy used for bonding the silicon condenser microphone and the circuit unit Resin spreads into undesired areas. Accordingly, it is possible to prevent contact defects from being caused between the contact surfaces of the case and the base due to adhesive or epoxy spreading to the contact portion of the case and the base.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it should be understood by those skilled in the art that changes may be made in form and form without departing from the spirit and scope of the invention as defined by the appended claims. Various changes were made in the details.

Description of drawings

Fig. 1 is a sectional view showing the packaging structure of a conventional silicon condenser microphone;

2 is a cross-sectional view showing the structure of a condenser microphone;

3 is a cross-sectional view showing a package structure of a silicon condenser microphone according to a first embodiment of the present invention;

FIG. 4 is a perspective view showing an exploded base of the package structure of FIG. 3;

5 is a cross-sectional view showing a packaging structure of a silicon condenser microphone according to a second embodiment of the present invention;

FIG. 6 is a perspective view showing an exploded base of the package structure of FIG. 5;

7 is a cross-sectional view showing a packaging structure of a silicon condenser microphone according to a third embodiment of the present invention;

FIG. 8 is a perspective view showing an exploded base of the package structure of FIG. 7 .

Detailed ways

The above objects and other objects, features and advantages of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 2 is a cross-sectional view showing the structure of a condenser microphone.

Referring to FIG. 2 , a gasket 104 and a vibrating plate 106 are stacked on a first side of a silicon wafer 100 , and a portion of a second side of the silicon wafer is etched to form a back plate 102 . The gasket 104 is formed by stacking an insulating film on the silicon wafer 100 and then patterning the insulating film. The vibration plate 106 is formed thereon with a conductive film. According to the illustrated structure, although the vibration plate 106 is disposed on the silicon chip 100, the positions of the vibration plate 106 and the back plate 102 can be exchanged when the vibration plate 106 and the back plate 102 are opposed to each other with the gasket 104 therebetween.

3 is a sectional view showing a package structure of a silicon condenser microphone according to a first embodiment of the present invention, and FIG. 4 is a perspective view showing an exploded base of the package structure of FIG. 3 .

Referring to FIG. 3 , the silicon condenser microphone 120 manufactured according to the above method is packaged with a circuit unit 140 . The circuit unit 140 generates an electric signal by causing the vibration plate 106 of the silicon condenser microphone 120 to vibrate due to a sound source.

According to the present invention, the silicon condenser microphone 120 and the circuit unit 140 are arranged on the substrate 160 having the rear chamber 174 . Preferably, the substrate 160 is composed of a ceramic material. The ceramic material is heat-resistant, and since the ceramic material has a thermal expansion coefficient approximately equal to that of silicon and metal constituting the silicon condenser microphone 120 and the circuit unit 140, problems such as deformation during high-temperature heat treatment or degradation of bonding characteristics do not occur, The ceramic material is therefore advantageous.

Air holes 172 are formed on the substrate 160 so that external air flowing into the silicon condenser microphone 120 can flow into the rear chamber 174 . Therefore, preferably, the silicon condenser microphone 120 is arranged on the portion where the air hole 172 is formed.

In addition, pillars 176 are formed in the rear chamber 174 of the substrate 160 . The rear chamber 174 is a hollow space between the upper surface of the substrate 160 and its lower surface. Therefore, since there is a possibility that the upper surface of the base 160 may collapse due to excessive impact from the outside, a pillar 176 is formed in the rear chamber 174 to ensure stability. Preferably, the struts 176 are constructed of a porous material such that the struts 176 are strong and resilient enough to support the ceramic material and allow free air circulation. Furthermore, although only one strut 176 is shown, the number and location of struts may vary.

The silicon condenser microphone 120 and the circuit unit 140 are bonded to the substrate 160 through die-bonding, and are electrically connected through wire bonding 190 . Since the adhesive used in the chip bonding process and the epoxy used to maintain the bond have low viscosities, they may spread into undesired areas. Accordingly, the protrusion 180 may be formed on the base 160 to prevent the adhesive and epoxy from spreading to undesired areas.

After the silicon condenser microphone 120 and the circuit unit 140 are arranged on the substrate 160 as described above, the housing 200 is arranged. An opening 210 is formed in the housing 200 and then covered with a sealant 220 . Since there is a small gap between the opening 210 and the sealant 220 , external sound sources can be transmitted to the silicon condenser microphone 120 inside.

According to the decomposed base 160 shown in FIG. 4, the base 160 is formed by combining the first chamber plate 160a, the second chamber plate 160b, and the third chamber plate 160c.

The first chamber plate 160 a serves as a lower surface of the base 160 . The second chamber plate 160b includes a rear chamber 174 and struts 176 . The third chamber plate 160c constitutes the upper surface of the base 160 and includes air holes 172 allowing air to flow into the rear chamber 174 . A protrusion 180 for preventing adhesive or epoxy from spreading is formed on the third chamber plate 160c.

The above structure is illustrated as a purely embodiment. Therefore, additional chamber panels may be incorporated between the first to third chamber panels.

5 is a sectional view showing a package structure of a silicon condenser microphone according to a second embodiment of the present invention, and FIG. 6 is a perspective view showing an exploded base of the package structure of FIG. 5 .

FIG. 5 shows a case where the size of the rear chamber 174 is larger than that of the substrate 160 shown in FIG. 3 .

The height of the base 160' increases along an edge portion of the upper surface of the base 160', except for a portion of the upper surface covered by the silicon condenser microphone 120 and the circuit unit 140. Referring to FIG. The inner space serves as the rear chamber 174 to expand the rear chamber 174 . As described above, since the size of the rear chamber is increased, the pressure in the rear chamber can be ignored, thereby improving the sensitivity of the microphone.

Although only the edge portion of the upper surface is increased in height in FIG. 5, the entire height of the substrate may be increased to have a structure surrounding the silicon condenser microphone and the circuit unit.

Referring to FIG. 6, a plurality of chamber plates 160a' to 160e' are combined to form a base 160'. Similar to the first embodiment, the first chamber plate 160a' constitutes the lower surface, and the second chamber plate 160b' includes the rear chamber 174 and the pillars 176.

Contrary to the first embodiment, the third chamber plate 160c' further includes a rear chamber 174 along a side edge portion other than a portion covered by the silicon condenser microphone 120 and the circuit unit 140 . The rear chamber 174 of the fourth chamber plate 160d' is joined to the third chamber plate 160c' aligned with the extra space of the rear chamber 174 . A fifth chamber plate 160e' is then disposed thereon to cover the upper surface.

7 is a sectional view showing a package structure of a silicon condenser microphone according to a third embodiment of the present invention, and FIG. 8 is a perspective view showing an exploded base of the package structure of FIG. 7 .

Figure 7 shows a structure in which a rear chamber 174 larger than that of the substrates 160 and 160' is obtained.

The height of the base 160 ″ increases along the edge portion of the upper surface of the base 160 ″ up to the height of the upper surface of the housing 200 , except a portion covered by the silicon condenser microphone 120 and the circuit unit 140 . Since in this case, the inner space of the base 160″ is used as the rear chamber 174, the rear chamber 174 can be maximized. In addition, since the height of the base 160″ is increased up to the case 200, the case 200 can be manufactured In order to have a flat structure, the manufacturing process is simplified compared with the case where the housing 200 has a "∩" shape.

In addition, the height of the part where the circuit unit 140 is arranged is different from that of the part where the silicon condenser microphone 120 is arranged, so that the rear chamber 174 below the silicon condenser microphone 120 may be larger. Although FIG. 7 shows a case where the height of the portion where the silicon condenser microphone 120 is arranged is higher than that of the portion where the circuit unit 140 is arranged, the height can be freely varied.

8, there is shown a plurality of chamber plates 160a" to 160g" required for forming the base 160" shown in FIG. 160″. Additional chamber panels can also be incorporated between them and the shape can also be changed.

Industrial Applicability

According to an embodiment of the present invention, a packaging structure of a silicon condenser microphone and a manufacturing method thereof are provided, wherein the substrate on which the silicon condenser microphone and the circuit unit are arranged is made of a heat-resistant ceramic material, and the ceramic material has an incompatibility with the silicon condenser microphone and the circuit unit. The coefficient of thermal expansion is close to the thermal expansion coefficient to prevent deformation and decrease in bonding properties due to heat during high-temperature heat treatment.

According to an embodiment of the present invention, there are provided a package structure of a silicon condenser microphone and a manufacturing method thereof, in which a base is formed by combining a plurality of chamber plates so that the shape can be changed in various ways and a space for a rear chamber can be formed.

According to an embodiment of the present invention, a package structure of a silicon condenser microphone and a manufacturing method thereof are provided, wherein a post is formed in a rear chamber to prevent a chamber plate from collapsing due to the rear chamber.

According to an embodiment of the present invention, a packaging structure of a silicon condenser microphone and a manufacturing method thereof are provided, and a protrusion is included on the surface (or upper part) of the substrate to prevent bonding of the silicon condenser microphone and the circuit unit agent or fixing epoxy into undesired areas.

Claims (2)

1. the encapsulating structure of a silicon based condenser microphone, this encapsulating structure comprises:

Substrate, it has a upper surface, on this upper surface, is furnished with silicon based condenser microphone and circuit unit; This substrate has rear chamber therein; This rear chamber is formed on the below of said silicon based condenser microphone and said circuit unit, and this substrate comprises pore, is used to supply air through being used to arrange between the upper surface and rear chamber of silicon based condenser microphone; Through combining the first Room plate, the second Room plate and the 3rd Room plate to form said substrate; The said first Room plate forms the lower surface of said substrate, and the said second Room plate comprises said rear chamber, and said the 3rd Room plate comprises said pore and forms said upper surface; With

Housing, its covering are arranged in silicon based condenser microphone and the circuit unit on the upper surface of said substrate, are used for they are protected.

2. method that is used to make the encapsulating structure of silicon based condenser microphone, this method comprises the steps:

(a) form a substrate; In this substrate, has rear chamber; This rear chamber is formed on the below of said silicon based condenser microphone and circuit unit; Wherein this substrate comprises pore, is used to supply between the upper surface and rear chamber of air through substrate, and this pore is arranged in the part place that waits to arrange silicon based condenser microphone and circuit unit of said upper surface;

(b) said silicon based condenser microphone and circuit unit are attached on the upper surface of said substrate; And

(c) cover said silicon based condenser microphone and circuit unit with a housing, to protect this silicon based condenser microphone and circuit unit;

Said step (a) comprising:

Preparation form the lower surface of said substrate the first Room plate, comprise the second Room plate of said rear chamber and comprise said pore and form the 3rd Room plate of said upper surface; And

The said first Room plate, the second Room plate and the 3rd Room plate are combined to form said substrate.

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