JP7345404B2 - MEMS device - Google Patents

Description

The present invention relates to a MEMS device.

MEMS devices using MEMS (Micro Electro Mechanical Systems) elements are used in various sensors such as pressure sensors, acceleration sensors, and microphones, and mirror devices such as optical scanners and digital mirror devices. By mounting a MEMS element on a mounting board, it becomes a MEMS device that can be connected to an external circuit.

The MEMS element is mounted on the mounting board by, for example, fixing the MEMS element with an adhesive and electrically connecting it with wire bonding. Since the MEMS element and the mounting board have different coefficients of thermal expansion, thermal stress generated between them may cause distortion in the MEMS element. On the other hand, a technique is known in which an elastic material having a predetermined thickness is used as an intermediate fixing layer between a sensor chip and a lead frame (see, for example, Patent Document 1). With this technology, the materials for the mounting board are limited, and in order to solve the problem of not being able to provide a sensor suitable for each application, a protrusion is provided on the mounting surface of the MEMS element, and the protrusion and the mounting board are connected via adhesive. MEMS devices are known (see, for example, Patent Document 2).

Japanese Patent Application Publication No. 3-289528 Japanese Patent Application Publication No. 2012-6092

However, in the MEMS element mounting structure of Patent Document 1, the entire frame-shaped lower surface of the MEMS element is bonded to the wiring board, so thermal stress may not be sufficiently reduced and distortion may occur in the MEMS element. There was sex. In the MEMS element mounting structure of Patent Document 2, it is possible to alleviate stress to a certain extent, but the adhesive placement (connection position ) was not. Therefore, there is a possibility that the mounting reliability including the connectivity of bonding wires and the accuracy of the operation of the MEMS element due to distortion may deteriorate.

A MEMS device according to one aspect of the present disclosure includes a wiring board, a square frame-shaped support portion having a first surface and a second surface opposite to the first surface, and located on the first surface of the support portion. a MEMS element including an element part, the element part has a frame part that overlaps with the support part, and a functional part located inside the frame part and connected to the frame part; The second surface of the supporting part and the wiring board are joined by a plurality of joining members arranged at intervals from each other on each of the four sides of the supporting part, and the second surface of the supporting part The interval between the bonding members on the first side is smaller than the interval between the bonding members on the second side, and an electrode to which a bonding wire is connected to a portion of the frame located on the first side. The electrode portion includes a first electrode that overlaps the bonding member on the first side portion when seen in plan view, and a second electrode located between the two adjacent bonding members in plan view.

According to the MEMS device of one aspect of the present disclosure, thermal stress is reduced by the point-like joints that are joined by the plurality of joint members arranged at intervals on each of the four sides of the support part. , the distortion of the entire MEMS element can be suppressed, and since the interval between the joining members on the first side of the four sides of the support section is small, the first side can be more firmly joined according to the position of the electrode. Since the distortion can be made smaller depending on the location or the shape of the MEMS element, the mounting reliability or the accuracy of the operation of the MEMS element can be improved.

FIG. 2 is a plan view showing a mounting structure of an example of a MEMS device. (a) is a sectional view taken along line AA in FIG. 1, and (b) is a sectional view taken along line BB in FIG. FIG. 7 is a plan view showing a mounting structure of another example of a MEMS device. (a) is a sectional view taken along line AA in FIG. 3, and (b) is a sectional view taken along line BB in FIG. 3. FIG. 7 is a plan view showing a mounting structure of another example of a MEMS device. (a) is a sectional view taken along line AA in FIG. 5, and (b) is a sectional view taken along line BB in FIG. FIG. 7 is a plan view showing a mounting structure of another example of a MEMS device. (a) is a sectional view taken along line AA in FIG. 7, and (b) is a sectional view taken along line BB in FIG. (a) is a plan view showing an example of a MEMS device, and (b) is a cross-sectional view taken along the line BB in (a). (a) is a plan view showing another example of the MEMS device, and (b) is a cross-sectional view taken along the line BB in (a). (a) is a plan view showing another example of the MEMS device, and (b) is a cross-sectional view taken along the line BB in (a).

A MEMS device according to an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the distinction between upper and lower in the following explanation is for convenience, and does not limit the upper and lower when the MEMS device is actually used. FIG. 1 is a plan view showing the mounting structure of an example of a MEMS device. 2(a) is a cross-sectional view taken along line AA in FIG. 1, and FIG. 2(b) is a cross-sectional view taken along line BB in FIG. FIG. 3 is a plan view showing the mounting structure of another example of the MEMS device. 4(a) is a cross-sectional view taken along line AA in FIG. 3, and FIG. 4(b) is a cross-sectional view taken along line BB in FIG. FIG. 5 is a plan view showing the mounting structure of another example of the MEMS device. 6(a) is a cross-sectional view taken along line AA in FIG. 5, and FIG. 6(b) is a cross-sectional view taken along line BB in FIG. FIG. 7 is a plan view showing the mounting structure of another example of the MEMS device. 8(a) is a cross-sectional view taken along line AA in FIG. 7, and FIG. 8(b) is a cross-sectional view taken along line BB in FIG. 9(a) is a plan view showing an example of a MEMS device, and FIG. 9(b) is a sectional view taken along the line BB in FIG. 9(a). FIG. 10(a) is a plan view showing another example of the MEMS device, and FIG. 10(b) is a sectional view taken along line BB in FIG. 10(a). FIG. 11(a) is a plan view showing another example of the MEMS device, and FIG. 11(b) is a sectional view taken along line BB in FIG. 11(a).

A MEMS device 600 according to one aspect of the present disclosure includes a wiring board 200 , a square frame-shaped support portion 110 having a first surface 111 and a second surface 112 opposite to the first surface 111 , and the support portion 110 of the support portion 110 . The MEMS device 100 includes an element section 120 located on the first surface 111. The element section 120 has a frame section 122 overlapping with the support section 110 and a functional section 121 located inside the frame section 122 and connected to the frame section 122. The second surface 112 of the support part 110 and the wiring board 200 are joined by a plurality of joining members 300 arranged at intervals on each of the four sides of the support part 110. Of the four sides of the support portion 110 , the interval between the joining members 300 on the first side 113 is smaller than the interval between the joining members 300 on the second side 114 .

In the example shown in FIGS. 1 and 2, the second surface 112 (lower surface) of the support portion 110 of the MEMS element 100 is bonded to the wiring board 200 with a bonding member 300. The joining members 300 are arranged at intervals in the circumferential direction of the frame-shaped support section 110. The joining members 300 are arranged at the same interval D3 on the upper side (top side), left side, and right side of the square frame-shaped support portion 110 of the MEMS element 100 in FIG. The MEMS element 100 is rectangular in plan view, and the support portion 110 is also rectangular in plan view. Therefore, the top side, which is the long side, is joined at three places, and the left and right sides, which are the short sides, are joined at two places. Although the number of joints and the number of joint members 300 arranged are different between the upper side and the left and right sides, there are a plurality of joint members 300 in both cases, and the distance between them is the same D3. On the other hand, the number of joints on the lower side (lower side), that is, the number of joint members 300 arranged, is four. The interval D1 between the joining members 300 at the lower side is smaller than the interval D3 between the joining members 300 at the upper side and the left and right sides. In the example shown in FIG. 1, the upper side and the left and right sides correspond to the second side 114, and the lower side corresponds to the first side 113.

Also in the example shown in FIGS. 3 and 4, the second surface 112 (lower surface) of the support portion 110 of the MEMS element 100 is bonded to the wiring board 200 with the bonding member 300. Further, the joining members 300 are arranged at intervals in the circumferential direction of the frame-shaped support portion 110. Two joining members 300 are arranged at the same interval D3 and joined at two places on the left side and right side of the square frame-shaped support portion 110 of the MEMS element 100 in FIG. On the other hand, the number of joints on the upper side and the lower side, that is, the number of joint members arranged is three. The MEMS element 100 in this example has a square shape in plan view, and the shape of the support portion 110 in plan view is also square. Therefore, the interval D1 between the joining members 300 on the upper side and the lower side is smaller than the interval D3 between the joining members 300 on the left and right sides. In the example shown in FIG. 3, the left and right sides correspond to the second side 114, and the upper and lower sides correspond to the first side 113.

In the examples shown in FIGS. 5 and 6 as well, the second surface 112 (lower surface) of the support portion 110 of the MEMS element 100 is bonded to the wiring board 200 with the bonding member 300. Further, the joining members 300 are arranged at intervals in the circumferential direction of the frame-shaped support portion 110. On the left side of the rectangular frame-shaped support portion 110 of the MEMS element 100 in FIG. 5, two bonding members 300 are arranged with an interval D3, and the left side is bonded at two places. On the other hand, the number of joint parts on the upper side and the lower side, that is, the number of joint members arranged, is three, and the interval therebetween is D2. Further, the number of joints on the right side, that is, the number of joint members arranged, is four, and the interval therebetween is D1. The interval D2 between the joining members 300 on the upper side and the lower side is smaller than the interval D3 between the joining members 300 on the left side. Furthermore, the spacing D1 between the joining members 300 on the right side is also smaller than the spacing D3 between the joining members 300 on the left side, and also smaller than the spacing D2 between the joining members 300 on the top and bottom sides. In the example shown in FIG. 5, the left side corresponds to the second side 114, and the upper side, the lower side, and the right side correspond to the first side 113. That is, the first side 113 is the side where the joining members 300 are joined at a smaller interval than at least one of the other sides.

In any of the examples shown in FIGS. 1 to 6, the MEMS element 100 is not bonded to the entire second surface 112 (lower surface) of the support portion 110, but by bonding members 300 arranged at intervals. That is, the MEMS element 100 and the wiring board 200 are joined at a plurality of point-shaped joints. Compared to the case where the entire surface is joined, since the joining member 300 is small and easily distorted, the stress is relaxed in the joining member 300, and the stress applied to the MEMS element 100 is reduced. Therefore, the possibility that the MEMS element 100 will be damaged due to stress is reduced. Further, since the distortion of the MEMS element 100 is small, the MEMS element 100 (the element portion 120 thereof) can operate with high precision.

Furthermore, each side of the support portion 110 is joined at a plurality of locations. Therefore, even with a smaller bonding member 300 that can more easily relieve stress, the MEMS element 100 is firmly fixed to the wiring board 200. Moreover, since the MEMS element 100 is easily mounted without tilting with respect to the wiring board 200, the MEMS device 600, such as various sensors and mirror devices, has higher accuracy.

By providing the first side portions 113 that are joined by the joining members 300 with small intervals, the side portions that should be bonded more firmly or the side portions that should cause less strain in the MEMS element 100 are set. be able to. Therefore, the MEMS device 600 has high mounting reliability and high operating precision of the MEMS element 100.

The MEMS element 100 is composed of an element section 120 that is a substantial element and a support section 110 that is shaped like a rectangular frame. The support part 110 is for forming a space between the element part 120 and the wiring board 200 in which the element part 120 can operate and fixing the element part 120 to the wiring board 200. It is. The element section 120 is located on the first surface 111 (upper surface) of the support section 110 and is integrated with the support section 110 . The element section 120 has a frame section 122 overlapping with the support section 110 and a functional section 121 located inside the frame section 122. The frame portion 122 has a square frame shape similar to the support portion 110. The functional part 121 is located inside the frame part 122 and above the through hole of the support part 110, and is connected to and integrated with the frame part 122. The functional section 121 and the frame section 122 are connected to some of the four sides of the frame section 122. The width of the connection part between the functional part 121 and the frame part 122 is shorter than the length of the side part of the frame part 122. In this way, the functional section 121 is suspended inside the frame section 122.

The functional unit 121 includes a movable part, and there are some that convert an external force such as sound pressure, pressure, or acceleration into an electric signal by displacement of the movable part, and others that move the movable part by an externally input electric current. The example shown in FIGS. 1 to 11 is a case where the MEMS element 100 is a mirror MEMS, and the angle of a circular mirror located at the center of the functional section 121 changes depending on the current input from the outside. In the examples shown in FIGS. 1 to 11, an external current is input to the electrode 123 provided on the frame portion 122. In the example shown in FIGS. Although not shown, wiring including a coil is provided from the electrode 123 to the vicinity of the mirror of the functional section 121.

The MEMS element 100 is mechanically fixed to a wiring board 200 with a bonding member 300 and electrically connected to wiring 220 of the wiring board 200 with a bonding wire 400, as shown in the examples shown in FIGS. 9 to 11, for example. Ru. One end of the bonding wire 400 is connected to the electrode 123 of the MEMS element 100, and the other end of the bonding wire 400 is connected to the connection pad 221 of the wiring board 200. The MEMS device 600 shown in FIG. 9 has the mounting structure shown in FIGS. 1 and 2, and the MEMS device 600 shown in FIG. 10 has the mounting structure shown in FIGS. 3 and 4. The MEMS device 600 shown in FIG. 11 has the mounting structure shown in FIGS. 5 and 6. In the example mounting structure shown in FIGS. 1 and 2, eight electrodes 123 are provided in a portion of the frame portion 122 located above the lower side portion of the support portion 110. In the mounting structure shown in FIGS. 3 and 4, four electrodes 123 are provided in each of the portions of the frame portion 122 located above the upper and lower sides of the support portion 110. In the example mounting structure shown in FIGS. 5 and 6, eight electrodes 123 are provided in a portion of the frame portion 122 located above the right side of the support portion 110.

In this way, the MEMS device 600 can have the electrode 123 to which the bonding wire 400 is connected in the portion of the frame portion 122 located on the first side portion 113. By arranging the bonding members 300 in a dotted manner, stress is relaxed, and the stress applied to the MEMS element 100 is reduced. The smaller the number of bonding members 300 (the number of bonding points), the higher the stress relaxation effect, but the smaller the number of bonding members 300, the lower the rigidity of the bond. Therefore, when connecting the bonding wire 400 to the electrode 123, it may become difficult to apply sufficient ultrasonic vibration, and a strong connection may not be possible. Furthermore, when the distance between the bonding members 300 is large, when the bonding wire 400 is bonded to the electrode 123 located between the two bonding members 300 in plan view, the MEMS element 100 may be damaged due to the pressure at that time. There is sex. Since the electrode 123 to which the bonding wire 400 is connected is located on the first side 113 where the bonding members 300 are arranged at small intervals, there is a possibility that the connectivity by wire bonding as described above will be reduced and the MEMS element 100 is reduced.

In the mounting structure of the example shown in FIGS. 1 and 2, there are two joints between the functional section 121 of the element section 120 and the frame section 122 at a portion of the frame section 122 located above the lower side of the support section 110. It is provided. The functional section 121 is connected to two locations on both ends of the lower side of the frame section 122 . In the mounting structure of the example shown in FIGS. 3 and 4, the joint portion between the functional section 121 and the frame section 122 is formed by attaching a 1/2 inch portion to a portion of the frame section 122 located above the upper side and the lower side of the support section 110, respectively. They are provided one by one. The functional section 121 is connected to a total of two locations, a central portion of the upper side and a central portion of the lower side of the frame portion 122. In the mounting structure of the example shown in FIGS. 5 and 6, the joint portion between the functional section 121 and the frame section 122 is attached to a portion of the frame section 122 located above the upper side and the lower side of the support section 110, respectively. They are provided one by one. The functional section 121 is connected to a total of two locations, a central portion of the upper side and a central portion of the lower side of the frame portion 122.

In this way, the MEMS device 600 can have the functional section 121 connected to the portion of the frame section 122 that overlaps with the first side section 113. In the examples shown in FIGS. 1 to 9, the functional section 121 is connected to one or two of the four sides of the frame section 122. In order for the whole or a part (movable part) of the functional part 121 suspended inside the frame part 122 to operate with high precision, the strain of the frame part 122 and the support part 110, which are the supports of the functional part 121, should be smaller. Good. In particular, it is better that the distortion in the portion to which the functional unit 121 is connected is small. The functional portion 121 is connected to a portion of the frame portion 122 that overlaps with the first side portion 113, and the first side portion 113 is a portion joined at a small interval. The first side portion 113 has a small strain due to stress, and the portion of the frame portion 122 overlapping the first side portion 113 also has a small strain. Therefore, the mounting structure allows the MEMS element 100 (the element portion 120 thereof) to operate with higher accuracy.

As described above, in the example shown in FIGS. 5 and 6, the right side of the support section 110 located below the portion of the frame section 122 where the electrode 123 is provided, and the functional section 121 of the frame section 122 are connected to each other. The three sides, the upper side and the lower side, of the support part 110 located below the connected part are the first sides 113. Therefore, the interval D1 of the joining member 300 that joins the right side part located below the electrode 123 and the joining member 300 that joins the upper side part and the lower part of the support part 110 located below the connection part of the functional part 121. The spacing D2 is smaller than the spacing D3 of the joining member 300 that joins the left side of the support portion 110.

Further, the distance D1 between the joining members 300 that join the first side portions 113 located under the electrodes 123 is the same as the distance D1 between the joining members 300 that join the first side portions 113 of the support portion 110 located under the connection portion of the functional portion 121. It is smaller than the interval D2 of 300. As described above, wiring is provided from the electrode 123 to the functional section 121. In order to facilitate routing of the wiring and to shorten the wiring, the electrode 123 can be provided near the connection part, that is, the electrode part 123 and the connection part can be provided on the same side of the frame part 122. As in the examples shown in FIGS. 5 and 6, the side portion of the frame portion 122 where the functional portion 121 is provided may be different from the side portion where the electrode 123 is provided. In this example, a MEMS element 100 that is rectangular in plan view is mounted on a square wiring board 200. Therefore, by providing the electrode 123 on the short side of the MEMS element 100, the length of the bonding wire 400 connecting the MEMS element 100 and the wiring board 200 can be shortened.
In this case, the interval between the joining members 300 located under the electrodes 123 can be made smaller than the other sides. The side portion of the support portion 110 located under the electrode 123 is not only exposed to thermal stress during bonding of the MEMS element 100 to the wiring board 200 or during subsequent bonding of the lid 500, but also during wire bonding. Since this stress is also applied, the interval between the joining members 300 at this side portion is made smaller.

The MEMS element mounting structure of the example shown in FIGS. 7 and 8 is different from the MEMS element mounting structure of the example shown in FIGS. 1 to 6 in the joining member 300. A lower side portion corresponding to the first side portion 113 is joined to the wiring board 200 by six joining members 300 arranged at intervals D1. Four joining members 300 are arranged at an interval D3 on the upper side having the same length, and two joining members 300 are arranged at an interval D3 on the left and right sides shorter than these. The upper side and the left and right sides correspond to the second side 114. Similarly, the interval D1 between the joining members 300 on the first side 113 is smaller than the interval D3 between the joining members 300 on the second side 114. In the examples shown in FIGS. 1 to 6, the joining member 300 located at the cutting position of the cross section is hatched, and the joining member 300 located deeper than the cutting position is shown without hatching. On the other hand, in the examples shown in FIGS. 7 and 8, only the joining member 300 in the cutting position is shown because the joining member 300 is small and difficult to distinguish.

The examples shown in FIGS. 1 to 6 show examples in which the bonding member 300 is an adhesive, and the width of the bonding member 300 is larger than the width (of the side portion) of the support portion 110. On the other hand, the examples shown in FIGS. 7 and 8 show examples in which the joining member 300 is a metal bump, and the width of the joining member 300 is smaller than the width (of the side part) of the support part 110. Also in this case, since the bond between the MEMS element 100 and the wiring board 200 is a point-like bond, the stress is relaxed and the stress applied to the MEMS element 100 is reduced. The MEMS device mounting structure of this example also has the first side 113 in which the interval D1 between the joining members 300 is smaller than the interval D3 between the joining members 300 on the other side (second side 114). , has the same effects as the examples shown in FIGS. 1 to 6.

The MEMS device 600 has the MEMS element 100 mounted on the wiring board 200 with the mounting structure described above. A MEMS element 100 is mounted on a wiring board 200 and fixed by a bonding member 300. Further, as in the examples shown in FIGS. 9 to 11, the electrode 123 of the MEMS element 100 and the connection pad 221, which is the wiring 220 of the wiring board 200, are electrically connected by the bonding wire 400. In these examples, the wiring board 200 has a recess, and the MEMS element 100 is bonded to the bottom surface of the recess with a bonding member 300. Further, a lid body 500 is attached to close this recess, and the MEMS element 100 within the recess is hermetically sealed. The inside of the recess can also be evacuated. It is also possible to mount the MEMS element 100 on a flat wiring board 200 and seal it with a cap-like lid 500 that covers the MEMS element 100 and bonding wires 400.

As described above, the examples shown in FIGS. 9 to 11 are examples in which the MEMS element 100 is a mirror MEMS, and light is exchanged between the MEMS element 100 and the outside of the MEMS device 600. Therefore, the lid 500 includes a translucent member 510 that transmits this light. In the example shown in FIG. 9, the lid 500 is composed only of a light-transmitting member 510, and the plate-shaped light-transmitting member 510 is bonded to the wiring board 200 with a bonding material 530 such as a resin adhesive. In the example shown in FIG. 10 and the example shown in FIG. 11, the lid body 500 is composed of a translucent member 510 and a frame member 520. A translucent member 510 is attached so as to close the opening of the frame member 520. The frame member 520 in the example shown in FIG. 10 is made of metal, for example, and the frame member 520 and the metal frame 230 provided on the wiring board 200 are joined by brazing filler metal containing solder or welding such as seam welding. . The frame member 520 in the example shown in FIG. 11 is made of ceramic, for example, and the frame member 520 and the top of the wiring board 200 are bonded by a bonding material 530 such as glass. The method of bonding the lid 500 to the wiring board 200 in each example is not limited to the above, and bonding may be performed using a bonding material 530 in other examples. When a brazing material is used as the bonding material 530, a frame-shaped metal film is provided on the lid 500 and the wiring board 200 so that the brazing material can be wetted and bonded, or a brazing material containing an active metal is used. A bonding member 300 that bonds the MEMS element 100 by heating during bonding by the bonding material 530 and a bonding material 530 that can bond at a heating temperature that does not damage the MEMS element 100 are used. Since joining by seam welding is joining by local heating, the influence of heat on the joining member 300 and the like is relatively suppressed.

The MEMS element 100 has the structure described above. It is manufactured by processing a silicon wafer using a semiconductor manufacturing process.

The MEMS element 100 has a movable part (vibrating part) in a functional part 121 such as an angular velocity sensor element, an angle sensor element, an acceleration sensor element, etc., for example. These detect physical quantities (mechanical quantities) such as the Coriolis force during rotational motion, the direction of action of gravity, or the force that causes acceleration in the functional unit 121, and convert them into electrical signals. Alternatively, the MEMS element 100 is, for example, a mirror device that includes a mirror as a movable part of the functional part 121, and the angle of the mirror changes depending on a current input from the outside.

The second surface 112 of the support portion 110, which is the lower surface of the MEMS device 100, is bonded and fixed to the mounting area 1b of the wiring board 200 by the bonding member 300. Thereafter, the electrode 123 of the MEMS element 100 and the connection pad 221 of the wiring board 200 are connected with the bonding wire 400 to be electrically connected to the wiring board 200. The above physical quantity (mechanical quantity) detected by the MEMS element 100 and converted into an electrical signal is electrically led out to an external circuit via the bonding wire 400 and the wiring 220. Alternatively, when an electric signal (current) input from an external circuit to the wiring 220 of the wiring board 200 is input to the MEMS element 100 via the bonding wire 400, the angle of the mirror changes according to the electric signal.

The wiring board 200 has wiring 220 provided on an insulating substrate 210. The insulating substrate 210 is a basic structural part of the wiring board 200 and has functions such as ensuring mechanical strength as the wiring board 200 and ensuring insulation between the plurality of wirings 220. The insulating substrate 210 has, for example, a square or rectangular shape when viewed from above (in plan view). Square and rectangular shapes include not only strict squares and rectangles, but also squares (strictly octagons) or rectangles with cut-off corners as in the example shown in Figure 3, or rectangles as in the example shown in Figure 5. Contains a positive direction or a rectangle with rounded corners. As described above, the insulating substrate 210 may have a flat plate shape or a shape having a recessed portion. The shape of the recessed portion in plan view is also square or rectangular.

The dimensions of the insulating substrate 210 are, for example, a rectangular side with a length of 5 mm to 10 mm and a thickness of 1 mm to 3 mm. If the insulating substrate 210 has a recess, the dimensions of the recess are, for example, a rectangular opening with a side length of 3 mm to 8 mm and a depth of 0.5 mm to 2 mm.

The insulating substrate 210 is formed by laminating a plurality of insulating layers made of an insulating material such as an aluminum oxide sintered body, a glass ceramic sintered body, a mullite sintered body, or an aluminum nitride sintered body.

If the insulating substrate 210 is made of, for example, an aluminum oxide sintered body, it can be manufactured as follows. That is, first, a ceramic green sheet that will become an insulating layer is produced. Raw material powders such as aluminum oxide and silicon oxide are formed into sheets together with a suitable organic binder and organic solvent to produce a plurality of square ceramic green sheets. Next, these ceramic green sheets are laminated to produce a laminate. The recess may be formed by providing a through hole in the ceramic green sheet using a mold or the like. Thereafter, the insulating substrate 210 can be manufactured by firing this laminate at a temperature of 1300 to 1600°C.

The wiring board 200 including the insulating substrate 210 can also be manufactured as a multi-chip board in which a plurality of board regions that become the wiring board 200 are arranged on a mother board. A plurality of wiring boards 200 can also be manufactured more efficiently by dividing a mother board including a plurality of board regions into each board region. In this case, dividing grooves may be provided along the boundaries of the substrate regions of the mother substrate. Further, after mounting the MEMS element 100 on each substrate area of a multi-chip board, this may be divided to obtain a plurality of MEMS devices 600.

Wiring 220 is provided on the surface and inside of the insulating substrate 210. For example, in the examples shown in FIGS. 1 to 11, a connection pad 221 for connecting to the MEMS element 100 is provided in a recess opening on the upper surface of the insulating substrate 210. The recess in these examples has a step, and the connection pad 221 is on the step. In the case of a recess without a step, a connection pad 221 can be provided on the bottom surface of the recess. Further, on the lower surface of the insulating substrate 210, there is a terminal electrode 224 for connection to an external electric circuit. These connection pads 221 and terminal electrodes 224 are electrically connected by a through conductor 222 and an internal wiring layer 223 provided inside the insulating substrate 210. The through conductor 222 penetrates the insulating layer, and the internal wiring layer 223 is arranged between the insulating layers. The terminal electrode 224 may be provided not on the lower surface of the insulating substrate 210 but from the lower surface to the side surface or on the side surface.

The wiring 220 mainly contains, as a conductor material, a metal such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, platinum, nickel, or cobalt, or an alloy containing these metals. Such a metal material is provided on the surface of the insulating substrate 210 as a metal layer such as a metallized layer or a plating layer. This metal layer may be one layer or multiple layers. Further, it is provided inside the insulating substrate 210 by metallization.

If the connection pad 221, internal wiring layer 223, and terminal electrode 224 of the wiring 220 are, for example, a tungsten metallized layer, a metal paste prepared by mixing tungsten powder with an organic solvent and an organic binder is applied to the insulating substrate 210. It can be formed by printing on a predetermined position of a ceramic green sheet using a method such as screen printing and firing. In addition, a plating layer of nickel, gold, etc. may be further deposited on the exposed surface of the metallized layer that will become the connection pad 221 and the terminal electrode 224 by a plating method such as electrolytic plating or electroless plating. good. In this case, when manufacturing the wiring board 200 or the MEMS device 600 in the form of a multi-chip board as described above, if the wiring in the plurality of board regions is electrically connected to each other, the wiring board 200 can be A plating layer can also be applied to the wiring 220 all at once. Further, the through conductor 222 can be formed by providing a through hole at a predetermined position of the ceramic green sheet prior to printing the metal paste described above, and filling this through hole with the same metal paste as described above. can.

As the bonding member 300 for bonding and fixing the MEMS element 100 to the wiring board 200, a resin adhesive such as epoxy resin can be used as in the examples shown in FIGS. 1 to 6 described above. When the bonding material is a resin adhesive, stress and vibration can be absorbed by the bonding member 300 by using a more flexible material such as silicone rubber or urethane rubber. Alternatively, a brazing material containing solder can also be used as the joining member 300. When using a brazing filler metal, it is preferable to use one that has a lower melting point and is more flexible. Further, as in the example shown in FIGS. 7 and 8 described above, a metal bump can be used as the joining member 300. The metal in this case should also be relatively soft, and for example, gold or solder can be used. When using a brazing material or a metal bump, a metal film to which a brazing material or the like can be bonded is provided on the second surface 112 of the support portion 110 of the MEMS element 100 and (the insulating substrate 210 of) the wiring board 200.

When the bonding member 300 is an adhesive, a liquid adhesive is applied on the wiring board 200 at a predetermined interval, the MEMS element 100 is placed on top of the liquid adhesive, and the adhesive is cured. MEMS element 100 can be fixed to wiring board 200. The liquid adhesive that is the precursor of the bonding member 300 can be cured by heating if it is a thermosetting type, and can be cured by irradiation with ultraviolet rays if it is an ultraviolet curable type. . If the adhesive is an ultraviolet curable adhesive, stress during bonding can be reduced.

When the bonding member 300 is a metal bump, a metal film is provided on the wiring board 200 by metallization and plating film similar to the wiring 220, and a bonding wire, for example, a thin gold wire, is bonded onto this metal film. Gold bumps can be formed by cutting the wire without stretching it. Bonding can be achieved by placing the MEMS element 100 on gold bumps provided at predetermined intervals and applying heat and pressure. A thin metal film may be provided on the second surface 112 of the support portion 110 of the MEMS element 100, and gold bumps may be provided in the same manner. In the case of a solder bump, it can be provided by providing a metal film on at least one of the MEMS element 100 and the wiring board 200, applying solder paste on the metal film, and heating and melting the solder to solidify it. MEMS element 100 and wiring board 200 can be bonded by placing MEMS element 100 on wiring board 200 with solder bumps in between and heating.

The MEMS element 100 fixed on the wiring board 200 with the bonding member 300 and electrically connected with the bonding wire 400 is sealed and protected from the external environment by the lid 500. As described above, the examples shown in FIGS. 9 to 11 are examples in which the MEMS element 100 is a mirror MEMS, so the lid body 500 includes a translucent member 510 that transmits this light. If it is not necessary to exchange light between the MEMS element 100 and the outside of the MEMS device 600, the lid 500 may not include the light-transmitting member 510. The lid body 500 at this time can be made of metal, ceramics, resin, or the like. As the bonding material 530 and bonding method between the lid 500 and the wiring board 200, the same bonding material 530 and method as in the case of the lid 500 having the translucent member 510 described above can be used. Further, the shape of the lid body 500 can be a flat plate shape when the wiring board 200 has a recessed portion, and a cap shape when the wiring board 200 is a flat plate shape.

Regarding the MEMS device 600, if the terminal electrode 224 provided on the lower surface of the insulating substrate 210 among the wiring 220 is electrically connected to an external electric circuit, the mounted MEMS element 100 is electrically connected to the external electric circuit. be done. That is, the MEMS element 100 and the external electric circuit are electrically connected to each other via the bonding wire 400 and the wiring 220. The external electric circuit is, for example, an electric circuit included in a circuit board mounted on devices such as smartphones and projectors, or various electronic control devices installed in automobiles.

100... MEMS element 110... Support part 111... First surface 112... Second surface 113... First side part 114... Second side part 120... Element part 121... ...Functional part 122...Frame part 123...Electrode 200...Wiring board 210...Insulating substrate 220...Wiring 221...Connection pad 222...Through conductor 223...Internal wiring Layer 224...Terminal electrode 230...Metal frame 300...Joining member 400...Bonding wire 500...Lid 510...Transparent member 520...Frame member 530...Joining Material 600...MEMS device

Claims (3)

a wiring board;
A MEMS element comprising a square frame-shaped support portion having a first surface and a second surface opposite to the first surface, and an element portion located on the first surface of the support portion,
The element portion has a frame portion overlapping with the support portion and a functional portion located inside the frame portion and connected to the frame portion,
The second surface of the support part and the wiring board are joined by a plurality of joining members arranged at intervals from each other on each of the four sides of the support part,
Among the four sides of the support part, the interval between the joining members on the first side is smaller than the interval between the joining members on the other sides ,
An electrode portion to which a bonding wire is connected is provided in a portion of the frame portion located on the first side portion,
a first electrode in which the electrode portion overlaps the bonding member in the first side portion in plan view;
A MEMS device including a second electrode located between two of the bonding members adjacent in plan view . The first electrode includes a third electrode that overlaps with one of the two adjacent joining members in plan view, and a fourth electrode that overlaps with the other of the two adjacent joining members,
The MEMS device according to claim 1, wherein the second electrode is located between the third and fourth electrodes. The MEMS device according to claim 1 or 2, wherein the functional section is connected to a portion of the frame portion that overlaps with the first side portion.

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