TWI449657B - Micro electro-mechanical system - Google Patents

Description

MEMS

The present invention relates to the field of microelectromechanical technology, and in particular to a microelectromechanical system.

Micro-Electro-Mechanical Systems (MEMS) is a combination of micro-electronic technology and precision machining technology. It integrates miniature sensors, actuators, signal processing and control circuits, interface circuits, A micro-mechanical electronic system that combines communication and power. MEMS can integrate the acquisition, processing and execution of information, featuring miniaturization, intelligence, versatility, high integration and suitability for mass production.

Typical devices for MEMS include miniature sensors and micro-brakes, see Hidenori Ishihara, et al., et al., March 1996, IEEE/ASME TRANSACTIONS ON MECHATRONICS, "Micor Mechatronics and Micro Actuators." Micro-electromechanical systems can be made into micro-optical electromechanical devices, micro biochemical wafers, micro-robots, micro-aircraft, micro-power systems, etc., and have broad application prospects in the fields of aviation, automotive, biomedicine, military, consumer electronics and other fields. .

One of the important processes in the manufacture of MEMS is the packaging of MEMS. MEMS packaging refers to the fabrication of protective layers to protect vulnerable components and circuits on MEMS wafers and to make connections to boards or other components to enable electrical connection of MEMS pads to boards or other components. The process. Generally in microcomputer In an electrical system, a package connection area is exposed from the package housing, wherein a connection pad is formed for electrical connection with other electrical components such as a circuit board. The circuit board is usually provided with a driving circuit of the MEMS system.

Typically thin copper wires are used to electrically connect the MEMS wafer to the drive board. However, when the MEMS is as small as the micron size, the area of the package connection area on the MEMS is too small, and the thin copper wire cannot be directly combined with the connection pad on the MEMS by the wire bonding process, so the MEMS can not be directly connected to the MEMS by using a thin copper wire. Circuit board.

Therefore, it is necessary to provide a microelectromechanical system that facilitates electrical connection to a circuit board.

Hereinafter, a microelectromechanical system and a packaging method thereof will be described by way of embodiments.

A microelectromechanical system comprising a microelectromechanical wafer and a first circuit board having a package connection region, wherein at least one connection pad is formed in the package connection region, wherein the MEMS further comprises a press-fit An electrical connection layer of the package connection region and a second circuit board, the second circuit board includes a first connection pad and a second connection pad connected to the first connection pad, and the electrical connection layer is disposed on the package connection The connection between the area and the second circuit board and the connection pad in the package connection area is electrically connected to the first connection pad. The second connection pad is provided with a wire, and the other end of the wire is connected to the first circuit board.

Compared with the MEMS in the prior art, the MEMS system uses an electrical connection layer to electrically connect the connection pads on the MEMS wafer to a second circuit board, so that a thin copper wire can be used in the mature wire bonding process. The MEMS wafer is electrically connected to other boards (eg, the board on which the driver circuit is located). Make the board mountable to the MEMS The side of the system helps to reduce the size of the entire MEMS.

100,200‧‧‧Microelectromechanical systems

10‧‧‧Microelectromechanical package

12‧‧‧Second circuit board

14, 24‧‧‧Electrical connection layer

16‧‧‧First board

101‧‧‧Microelectromechanical Wafer

102‧‧‧Top cover

103‧‧‧ bottom cover

104‧‧‧Package connection area

105, 205‧‧‧ connection pads

120‧‧‧Insulation

121, 121a, 221, 221a‧‧‧ first connection pad

122, 122a‧‧‧second connection pad

123‧‧‧Electrical circuit

126, 126a‧‧‧ vias

141‧‧‧Adhesive

142, 242‧‧‧Connected ball

163, 164‧‧ ‧ pads

161,161a‧‧‧ wires

162, 162a‧‧‧ solder balls

204‧‧‧Connecting bumps

1 is a schematic diagram of a microelectromechanical system provided by a first embodiment of the present technical solution.

2 is a schematic diagram of a microelectromechanical system provided by a second embodiment of the present technical solution.

The MEMS system and its packaging method provided by the technical solution will be further described in detail below with reference to the accompanying drawings and embodiments.

Referring to FIG. 1 , the microelectromechanical system 100 provided by the first embodiment includes a microelectromechanical package 10 , a first circuit board 16 , an electrical connection layer 14 , and a second circuit board 12 .

The microelectromechanical package 10 includes a microelectromechanical wafer 101, a top cover 102 and a bottom cover 103. The microelectromechanical wafer 101 refers to a substrate material of single crystal germanium (Si), germanium dioxide (SiO2), germanium nitride (SiN), SiOn Insulator (SOI), etc., by microelectronic technology. And micro-machining technology is combined to manufacture a wafer with micro-mechanical components and microelectronic circuits. The MEMS wafer 101 is packaged between the top cover 102 and the bottom cover 103. A package connection region 104 is provided at one corner of the MEMS wafer 101. The package connection region 104 is exposed from the top cover 102. Two connection pads 105 (eg, aluminum disks) are formed within the package connection region 104. The connection pads 105 are connected to circuitry within the MEMS wafer 101. It can be understood that the number of connection pads 105 is related to the internal circuit design of the MEMS wafer 101, which may vary according to circuit design requirements, for example, it may be one or plural.

The second circuit board 12 includes an insulating layer 120, two first connection pads 121, 121a formed on opposite surfaces of the insulating layer, and two second connection pads 122, 122a. However, the first connection pads 121, 121a and the second connection pads 122, 122a are also It may be formed on the same surface of the insulating layer 120. The first connection pad 121 and the second connection pad 122 are connected by a conductive line 123 and a via hole 126. The first connection pad 121a and the second connection pad 122a are connected by a conductive line (not shown) and a via hole 126a. The conductive vias 126, 126a may be filled with a conductive paste such as copper paste or silver paste. The second circuit board 12 can be a rigid circuit board or a flexible circuit board.

The electrical connection layer 14 may be an anisotropic conductive paste (ACP) or an anisotropic conductive film (ACF). The electrical connection layer 14 includes an insulating resin adhesive 141 and a plurality of connecting balls 142 dispersed therein. The connecting balls 142 each include conductive particles and an insulating layer coated on the surface of the conductive particles. The surface of the conductive particles is formed with a microstructure, and when the conductive particles are pressed, the microstructure of the surface can pierce the insulating layer at the surface thereof. When the electrical connection layer 14 is pressed between the package connection region 101 and the interposer 12, since the connection pad 105 protrudes from the surface of the package connection region 101, it is located between the connection pad 105 and the first connection pads 121, 121a. The electrical connection layer 14 is pressed to a high degree, the connecting balls 142 are close to each other and contact, and due to the pressure, the microstructure of the surface of the conductive particles of the connecting ball 142 pierces the insulating layer on the surface thereof, so that the connecting balls 142 are in contact with each other. Conduct each other. Thereby, the connection pad 105 is electrically connected to the first connection pads 121, 121a. The other regions of the electrical connection layer 14 are still in a dispersed state due to the low degree of pressure, that is, the electrical connection layer remains electrically insulated. It can be understood that the distance between the two connection pads 105 should be larger than the diameter of the connecting ball 142, so that the same connection ball 142 does not contact the two connection pads at the same time, resulting in a short circuit.

A driving circuit of the MEMS chip 101 can be mounted on the first circuit board 16. In this embodiment, two pads 163, 164 are formed on the first circuit board 16. Second connection pad 122 The pads 163 are electrically connected by thin wires (for example, thin copper wires) 161. The second connection pad 122a and the pad 164 are electrically connected by a thin wire (for example, a thin copper wire) 161a. The wire conductors 161, 161a can be fixed to the second connection pads 122, 122a by solder balls 162, 162a, respectively. To save the area occupied by the MEMS 100, the first circuit board 16 can be perpendicular to the plane in which the MEMS package 10 is located. In general, the second circuit board 12 is parallel to the plane of the MEMS package 10, so that the first circuit board 16 is also generally perpendicular to the plane of the second circuit board 12. However, it can be understood that since the second circuit board 12 can be bent at a certain angle when the flexible circuit board is a flexible circuit board, the first circuit board 16 can also be at an angle to the second circuit board 12.

When the MEMS 100 of the present embodiment is assembled, first, the MEMS package 10, the second circuit board 12, and the electrical connection layer 14 are provided. Next, the electrical connection layer 14 is disposed on the surface of the second circuit board 12 and covers the first connection pads 121, 121a. At this time, the electrical connection layer 14 is not compressed, wherein the connection balls 142 are separated from each other, and the electrical connection layer 14 is not electrically conductive. Finally, the second circuit board 12 having the electrical connection layer 14 is laminated with the microelectromechanical package 10 and the electrical connection layer 14 covers the package connection region 101 of the microelectromechanical package 10. The electrical connection layer is pressed between the second circuit board 12 and the microelectromechanical package 10, as described above, and is placed between the two connection pads 105 and the first connection pads 121, 121a when pressed. The connecting balls 142 are in contact with each other and electrically conducted. Therefore, the connection pad 105 and the first connection pads 121, 121a are electrically connected, respectively. For example, a thermal head can be used to heat and press the second circuit board. It can be understood that in order to smoothly complete the hot pressing action, the shape of the thermal head needs to be matched with the second circuit board in the microelectromechanical package 10.

In the MEMS 100 of the present embodiment, the connection pads 105 on the MEMS wafer 101 are connected to the first connection pads 121, 121a of the second circuit board 12, and further to the second connection pads 122 in the circuit board 12, 122a is electrically conductive. When in the second connection pads 122, 122a When the thin copper wire is connected, the thin copper wire is electrically connected to the connection pad 105. It is therefore very convenient to connect the microelectromechanical 100 of the present embodiment to the circuit board through a thin copper wire.

Referring to FIG. 2, the MEMS 200 provided by the second embodiment is similar to the MEMS 100 of the first embodiment except that a connection bump 204 is formed on the surface of each of the connection pads 205. The connection bumps 204 may be formed of a high conductivity metal such as gold, silver or copper. The bump process of the prior art can be used to form the connection bumps 204. In this embodiment, the connecting bumps 204 are hemispherical, however, it can be understood that the connecting bumps 204 may have other shapes, for example, a semi-ellipsoidal shape, a frustum shape, or the like.

In this embodiment, the first connection pads 221, 221a and the corresponding connection pads 205 are respectively connected by a connection bump 204 and a connecting ball 242. In this case, since the connection bumps 204 penetrate into the interior of the electrical connection layer 24, that is, the electrical connection layer 24 of the region is more compressed, it is easier to achieve mutual conduction of the connection balls 242 in the region. In this case, the diameter of the connecting balls 242 in the electrical connection layer 24 can be made much smaller than the thickness of the electrical connection layer 24, so the distance between the connection pads 205 can be further reduced. That is, the area of the package connection area 204 can be further reduced. The MEMS volume of this embodiment can be further reduced.

Compared with the MEMS system of the prior art, the MEMS system in the above embodiments uses an electrical connection layer to electrically connect the connection pads on the MEMS wafer to a second circuit board, so that the mature wire bonding process can be adopted. The MEMS pad is electrically connected to other boards (such as the board on which the drive circuit is located) using thin copper wires. The board can be mounted on the side of the MEMS, which helps to reduce the size of the entire MEMS.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and cannot be limited thereto. The scope of the patent application for this case. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

100‧‧‧Microelectromechanical systems

10‧‧‧Microelectromechanical package

12‧‧‧Second circuit board

14‧‧‧Electrical connection layer

16‧‧‧First board

101‧‧‧Microelectromechanical Wafer

102‧‧‧Top cover

103‧‧‧ bottom cover

104‧‧‧Package connection area

162, 162a‧‧‧ solder balls

105‧‧‧Connecting mat

120‧‧‧Insulation

121, 121a‧‧‧ first connection pad

122, 122a‧‧‧second connection pad

123‧‧‧Electrical circuit

126, 126a‧‧‧ vias

141‧‧‧Adhesive

142‧‧‧Connecting ball

161,161a‧‧‧ wires

163, 164‧‧ ‧ pads

Claims (7)

A microelectromechanical system comprising a microelectromechanical wafer and a first circuit board having a package connection region, wherein at least one connection pad is formed in the package connection region, the improvement being that the microelectromechanical system further comprises a pressure And a second circuit board including a first connection pad and a second connection pad connected to the first connection pad, the electrical connection layer is disposed on the layer Between the package connection region and the second circuit board, and electrically connecting the connection pads in the package connection region to the first connection pad, the second connection pad is provided with a wire, and the wire is connected to the second connection by solder balls a pad, the other end of which is connected to the first circuit board, the first circuit board being perpendicular to a plane in which the MEMS and the second circuit board are located. The MEMS system of claim 1, wherein the package connection region is formed with two connection pads, the second circuit board includes two first connection pads and two second connection pads, each The first connection pad is electrically connected to the corresponding second connection pad, and the electrical connection layer electrically connects each connection pad in the package connection area to the corresponding first connection pad. The MEMS according to claim 1, wherein the electrical connection layer comprises an anisotropic conductive film or an anisotropic conductive paste, comprising a connecting ball comprising a plurality of uniformly distributed, the connecting ball comprising conductive particles And an insulating layer covering the conductive particles, the conductive particles are formed with a microstructure on the surface thereof, and when the electrical connecting layer is pressed, the connecting balls in the pressed region contact each other and the microstructure pierces the insulating layer to be pressed Conductive conduction in the direction. The MEMS according to claim 1, wherein the first connection pad and the second connection pad are connected by a conductive line and a via hole. The MEMS according to claim 1, wherein the connection pads in the package connection region are formed with connection bumps on each surface. The MEMS according to claim 1, wherein the driving circuit of the MEMS is formed in the first circuit board. The MEMS system of claim 1, wherein the second circuit board is a flexible circuit board.