JPH09269336A - G microswitch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a G microswitch whose size is small, which is suitable for mass producitivity, whose performance is high and whose reliability is high. SOLUTION: A silicon substrate 2 is fine worked, a beam 4 and a moving mass 5 are formed, at least one moving contact 14 is installed at the moving mass 5 which is supported by the beam 4, a fixed contact 15 is installed so as to face the moving contact 14, and the center of gravity of the moving mass 5 is arranged on the central axis of the beam 4. The thickness and the width of the moving mass 5 are set at values which are sufficiently larger than those of the beam 4, and the moving contact 14 and the fixed contact 15 are constituted of a high-melting-point metal material. An electrode for self-diagnosis and an electrode for prebias are arranged so as to face the moving mass 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro G switch for various safety devices, and more particularly to a micro G switch used in an automobile airbag system or the like.

[0002]

2. Description of the Related Art Conventionally, as a G switch (that is, an acceleration switch) of this type, a mechanical G switch described in JP-A-6-43181 or TRANSDUCERS'87, pp410 is used.
There is known a micro G switch manufactured by microfabrication of a silicon plate described in No. 413.

[0003]

The mechanical G switch has a problem that it has a large size and does not have a self-diagnosis function. Although the micro G switch is small in size, it also has a problem that it does not have a self-diagnosis function. Moreover, both of them could only detect acceleration in one direction. In particular, the latter type has the following other problems. The small acceleration (that is, G) could not be detected, and the sensitivity was low. It was easy to feel the acceleration of the component orthogonal to the acceleration in the direction to be detected, that is, the sensitivity of the other axis was large. The production yield was poor and mass production was not possible. After the switch was turned on in response to the pulsed acceleration, this on state could not be maintained for a long time. Further, due to the problem of welding of the switch section, when the switch is turned on and the acceleration becomes zero, the switch itself cannot be turned off without reliability.

An object of the present invention is to provide a micro G switch which is small in size, suitable for mass production, high performance and high reliability.

[0005]

A beam and a movable mass are formed by finely processing a silicon plate, and at least one movable contact is provided on the movable mass supported by the beam, and a fixed contact is provided facing the movable contact. The center of gravity of the movable mass was placed on the central axis of the beam. The thickness and width of the movable mass are made sufficiently larger than those of the beam, and the movable contact and the fixed contact are made of a high melting point metal material. Electrodes for self-diagnosis and electrodes for pre-bias were arranged facing the movable mass. The movable mass was provided with air circulation grooves and air circulation holes. In some cases, a second movable mass and beam were placed between the movable mass and the beam. Form a MOS switch on a silicon plate,
The conductor portion electrically connected to the gate portion of this MOS switch was opposed to the movable mass. A function of limiting the current flowing through the switch part to a certain value or less was formed in the silicon plate.
A function of keeping the ON state of the MOS switch for a long time is provided in the silicon plate. The micro G switch part and the power element part were integrated in the same silicon plate so that they could be mounted in the same package together with the crash sensor.

Next, how the above problems are solved by the above means will be described in more detail. The size of the G switch is reduced by finely processing the silicon plate to form the micro G switch. The micro G switch part and the power element part are integrated in the same silicon plate,
By allowing it to be mounted in the same package with the crash sensor, the size of the control module for the airbag system can be reduced. By providing a movable contact on both sides of the movable mass supported by the beam and a fixed contact facing the movable contact, it is possible to detect acceleration in two directions (acceleration in the + direction and acceleration in the − direction). By arranging the center of gravity of the movable mass on the central axis of the beam, the sensitivity of other axes can be reduced to zero. By making the thickness and width of the movable mass sufficiently larger than that of the beam, the sensitivity of the micro G switch is increased,
Enabled to detect small acceleration. MO on silicon plate
A very small acceleration can be detected by forming an S switch, and facing the movable mass with a conductor part electrically connected to the gate part of this MOS switch and controlling the potential of the gate part according to the acceleration. did. Prevents welding between the movable electrode and the fixed electrode by forming the function of limiting the current flowing through the switch to a certain value or less in the silicon plate, and by configuring the movable contact and the fixed contact with a metal material with a high melting point. It is possible to obtain a reliable and highly reliable G switch. Is it possible to operate the G switch by disposing the self-diagnosis electrode facing the movable mass and displacing the movable mass by electrostatic force? Is not it? Enabled active self-diagnosis. By finely processing the thickness and width of the movable mass and the beam with high accuracy, the magnitude of the acceleration to be detected can be suppressed within a certain narrow region, and the manufacturing yield can be improved. By providing an electrode for pre-bias and adjusting the value of the voltage applied to this electrode, it is possible to adjust the magnitude of the acceleration at which the movable mass starts to be displaced to a constant value, and further increase the yield during manufacturing. . It is possible to optimize the damping amount of the movable mass and the beam system by providing an air circulation groove or an air circulation hole in the movable mass or by disposing the second movable mass and the beam between the movable mass and the beam. Therefore, the state in which the switch is on can be maintained for a long time even after the acceleration becomes zero. Further, by providing the function of keeping the ON state of the MOS switch for a long time in the silicon plate, it is possible to similarly keep the state where the switch is on even after the acceleration becomes zero.

[0007]

1 shows an embodiment of a micro G switch according to the present invention. The micro G switch is composed of a laminated body of a glass plate 1, a silicon plate 2 and a glass plate 3, and the silicon plate 2 is finely processed by etching to form a beam 4 and a movable mass 5. The movable mass 5 is supported by the beam 4, and a movable contact 14 is provided on a part of the movable mass 5.
The fixed contact 1 is provided on the bottom surface of the glass plate 1 so as to face the movable contact 14.
5 are arranged. The fixed contact 15 is electrically connected to the upper surface of the glass plate 1 via the wiring lead 12 formed on the bottom surface of the glass plate 1, the three-dimensional pillar 13 of silicon, and the wiring lead 9 formed on the inner surface of the through hole 7 formed on the glass plate 1. Be drawn to. Here, the three-dimensional column 13 is a column-shaped column obtained by etching the silicon plate 2, is mechanically separated from the frame 16, and is electrically insulated from the movable mass 5. Similarly, the movable contact 14 is electrically connected to the upper surface of the glass plate 1 through the movable mass 5, the beam 4, the frame portion 16 of the silicon plate 2, and the wiring lead portion 8 formed on the inner surface of the through hole 6 formed in the glass plate 1. Have been pulled out. When the acceleration of the component perpendicular to the surface of the movable mass 5 acts, the movable mass 5 supported by the beam 4 is displaced to bring the movable contact 14 and the fixed contact 15 into contact with each other. As a result, both contacts are electrically connected and the magnitude of the acceleration acting on the micro G switch can be detected. As shown in the drawing, the beam 4 is formed on the axis of the center of gravity of the movable mass 5, so that a micro G switch with extremely small sensitivity to the other axis can be obtained. By making the thickness of the beam 4 sufficiently smaller than the thickness of the movable mass 5, the movable contact 14 can contact the fixed contact 15 with a small acceleration. That is, a highly sensitive micro G switch can be obtained. Further, by finely processing the thickness and width of the movable mass 5 and the beam 4 by etching with high accuracy, it becomes possible to suppress the magnitude of the acceleration to be detected within a certain narrow region, and manufacture the micro G switch. The time yield can be improved. The laminated body composed of the glass plate 1, the silicon plate 2 and the glass plate 3 is obtained by bonding the glass plate 1 and the glass plate 3 to both surfaces of the silicon plate 2 by well-known anodic bonding. At this time, since the size of the space 17 between the movable mass 5 and the glass plate 1 and the size of the space 18 between the movable mass 5 and the glass plate 3 are as small as several microns, the height at the time of bonding should be improved unless some measures are taken during the anodic bonding. The movable mass 5 is attracted to either the glass plate 1 or the glass plate 3 by the electrostatic force due to the voltage and adhered to the glass plate. In order to prevent this, the metal thin films 10 and 11 electrically connected to the silicon plate 2 are formed on the surface of the glass plate facing the movable mass 5 by sputtering or vapor deposition, and the movable mass 5 is formed at the time of anodic bonding. The potential difference acting between the glass plate 1 and the glass plate 3 was set to zero so that the electrostatic force would not act.

Another embodiment of the micro G switch according to the present invention is shown in FIG. From this figure, the same elements as those in FIG. 1 are denoted by the same numbers. Also, the numbers are omitted for the elements that are not used in the description. This drawing shows an embodiment in which the surface of the movable mass 5 is deeply etched to increase the dimensions of the gaps 17 and 18 between the movable mass 5 and the upper and lower glass plates. By doing so, the electrostatic force generated between the movable mass 5 and the upper and lower glass plates at the time of anodic bonding can be reduced, so that the metal thin films 10 and 11 as shown in FIG. 1 become unnecessary. Instead, the movable contact 14 is replaced by a small convex portion 19 on the surface of the movable mass 5.
Is provided. By disposing the movable contact also on the lower portion of the movable mass 5 and the fixed contact on the lower glass plate so as to face the movable contact, it is possible to provide a micro G switch capable of detecting acceleration components in both positive and negative directions.

Another embodiment of the micro G switch according to the present invention is shown in FIG. This figure shows an example in which an electrode 22 for pre-bias is provided on the lower glass plate 3 so as to face the surface of the movable mass 5 having no movable contact. The electrode 22 for pre-bias is provided on the glass plate through the wiring lead portion 23 provided so as to bypass the solid column 13, the solid column 25, and the wiring lead portion 21 provided on the inner surface of the through hole 20 processed in the glass plate 1. 1 is electrically drawn to the upper surface. On the surface of the movable mass 5, a protrusion 24 of an insulating material such as a thermal oxide film of silicon is formed. The movable mass 5 is attracted to the glass plate 3 side so that the insulator protrusion 24 of the movable mass 5 contacts the electrode 22 by the electrostatic force generated by the voltage applied to the electrode 22. The size of the gap 18 between the movable mass 5 and the electrode 22 is uniquely determined by the height of the protrusion 24 of the insulator. By adjusting the magnitude of the voltage applied from the outside of the micro G switch to the electrode 22 for pre-bias via the lead portion 21, the magnitude of the force that pulls the movable mass 5 toward the electrode 22 side can be freely controlled. . As a result, it is possible to accurately determine the magnitude of acceleration when the movable mass 5 leaves the electrode 22, that is, the magnitude of acceleration when the movable contact and the fixed contact of the micro G switch come into contact (on state). A micro G switch with high yield can be provided.

Another embodiment of the micro G switch according to the present invention is shown in FIG. An electrode 26 for self-diagnosis is formed on the upper glass plate 1 so as to face the movable mass 5. Electrode 26
Is a wiring lead portion 2 provided so as to bypass the solid pillar 13.
7, the three-dimensional column 25 and the glass plate 1 through the lead portion 21 provided on the inner surface of the through hole 20 formed in the glass plate 1.
Is electrically drawn to the upper surface of. Electrode 2 for self-diagnosis from outside the micro G switch via the lead portion 21
By applying a voltage to 6, the movable mass 5 is moved by electrostatic force.
Can be drawn toward the electrode 26 to bring the movable contact and the fixed contact of the micro G switch into contact (on state). Thus, by providing the self-diagnosis electrode 26 facing the movable mass 5 and displacing the movable mass 5 by electrostatic force, is the micro-G switch actually operable? Is not it? Can actively self-diagnose.
For example, it is possible to actively detect that there is dust or the like in the space 17 and the device is in an inoperable state.

Another embodiment of the micro G switch according to the present invention is shown in FIG. This drawing shows a schematic plan view of the silicon plate 2 part in the micro G switch shown in FIG. The movable mass 5 is supported by the two beams 4, and a movable contact 14 is provided at the tip and center of the movable mass 5. The three-dimensional columns 13 and 25 are arranged as shown in the figure, and are mechanically separated from the frame portion 16 of the silicon plate 2 and electrically insulated.
It should be noted that FIG. 4 which is a cross section of the micro G switch is schematically shown, and the positions of the solid columns 13 and 25 are different between FIG. 4 and FIG. The wiring lead portions below the through holes 6, 7 and 20 in the previous figure are 8, 9 and 21, respectively, and are formed by forming a thin metal film on the surface of the silicon member by sputtering or vapor deposition. Further, when the responsiveness is particularly required as the micro G switch, a groove having a depth of several microns to several tens of microns as shown by 28 may be formed on the surface of the movable mass 5 by etching. This is an air flow groove that improves the fluidity of air in the gap between the glass plate and the silicon plate and controls the amount of air damping in this portion. It is possible to optimize the damping amount of the movable mass 5 and the beam 4 system, improve the response of the micro G switch, or keep the switch on for a long time even after the acceleration becomes zero. Can be made.

FIG. 6 shows an example of a method of mounting the micro G switch according to the present invention. This figure shows an example of a method for mounting a micro G switch on a control module for an automobile air bag system. Micro G
By a method in which the lead portions 8 and 9 of the switch 200 are mechanically joined and electrically connected to the conductive pad portion (not shown in the figure!) On the surface of the module 31 by the solder layers 29 and 30. is there. Thus, by mounting the micro G switch directly on the module 31, the size of the control module for the airbag system can be reduced. Another embodiment of the micro G switch according to the present invention is shown in FIG. This figure shows a micro G switch obtained by etching a sacrificial layer on an SOI substrate. Silicon plate 34 (element forming substrate), thermal oxide film 33, silicon plate 3
This is a method of forming a movable part 44 composed of a movable mass and a beam on the silicon plate 32 by etching the silicon plate 34 part of the SOI substrate composed of 2 (support substrate) with silicon and the thermal oxide film 33 part with the sacrificial layer. The SOI substrate is obtained by directly bonding the element formation substrate to the support substrate via the thermal oxide film, and then polishing the element formation substrate on the upper surface to a desired thickness. The micro G switch is electrically connected to an external signal processing circuit or the like through the lead portions 41, 42 and 43 wired in the through holes 38, 39 and 40 processed into the glass plate 1 joined onto the silicon plate 34. Wired. Here, the wiring lead portions 42 and 43 are electrically connected to silicon solid columns 36 and 37, which are electrically insulated from the frame portion 35 of the silicon plate 34, respectively.
Further, the SOI substrate may be one in which polycrystalline silicon is epitaxially grown as an element forming substrate on the surface of a supporting substrate on which a thermal oxide film is formed.

FIG. 8 is a schematic plan view of the silicon plate 34 in the micro G switch shown in FIG. The movable part 44 in the previous figure is a movable mass 4 supported by three beams 45.
It is composed of 6. Movable contacts 49, 49a are provided at the central portions on both sides of the movable mass 46, and fixed contacts 48,
48a is arranged. The fixed contacts 48 and 48a are fixed portions 47 and 5 which are integrated with the solid columns 36 and 37, respectively.
It is formed to 0 as shown in the figure. Here, the three-dimensional columns 36 and 37 of silicon are respectively the frame portions 35 of the silicon plate 34.
And are electrically insulated. The micro G switch in this figure detects the acceleration of a component parallel to the surface of the silicon substrate 34 and brings the movable contact 49 and the fixed contact 48 into contact with each other or the movable contact 49a and the fixed contact 48a into contact with each other. When the acceleration in the direction of contact between the movable contact 49 and the fixed contact 48 is defined as the positive direction, the acceleration in the direction of contact between the movable contact 49a and the fixed contact 48a is the negative direction. In this way, it is possible to realize a micro G switch capable of detecting acceleration components in both positive and negative directions. The wiring lead portions 41, 4
The movable contact and the fixed contact of the micro G switch unit are electrically connected to an external signal processing circuit and the like via 2 and 43.

Another embodiment of the micro G switch according to the present invention is shown in FIG. The example of this drawing differs from the switch shown in FIG. 7 in the method of pulling out the movable part and the leads. Similar to the case shown in FIG. 7, the silicon etching and the thermal oxide film 33 of the silicon plate 34 of the SOI substrate including the silicon plate 34 (element forming substrate), the thermal oxide film 33, and the silicon plate 32 (supporting substrate). The movable portion 53 including the movable mass and the beam is formed on the silicon plate 32 by etching the sacrifice layer of the portion. A cap 51 made of glass, silicon or the like is bonded onto the silicon plate 34 so as to seal the space 52 above the movable portion 53. The movable contact and the fixed contact provided in the space 52 are electrically connected to the pad 54 provided on the silicon plate 34 via the wiring lead portion 55 provided at the bottom of the cap 51. The contact of the switch is connected to the signal processing circuit outside the micro G switch via the pad 54.

FIG. 10 shows a schematic plan view of the vicinity of the movable portion 53 in the micro G switch shown in FIG. The movable part 53 in the previous figure is a movable mass 57 supported by two beams 56.
Consists of The beam 56 has a fixed end 64 and is firmly fixed on the thermal oxide film 33 in the previous figure. The movable mass 57 has a comb-tooth shape having protrusions 58 and 59.
Movable contacts 62 and 62a are provided on the convex portion 58, and fixed contacts 61 and 61a are arranged facing the movable contacts. The fixed contacts 61, 61a are formed on the protrusion 60 of the fixed portion 63 fixed on the thermal oxide film. The micro G switch in this figure can detect positive and negative acceleration components parallel to the surface of the silicon plate 34 and orthogonal to the two beams 56. The wiring lead portion 55 and the pad 54 are not shown in this figure.

FIG. 11 shows an example in which the micro G switch according to the present invention is applied to an integrated ignition device for an automobile airbag system. The micro G switch 65 has a resistor 6
It is connected in series with the power supply Vs via 6. The resistor 66 limits the current flowing through the micro G switch 65 to a certain value or less. As a result, since the welding due to the heat generation between the movable contact and the fixed contact does not occur, a highly reliable micro G switch can be obtained. The resistor 66 may be formed by diffusion into the silicon plate described above or may be carried by the elongated beam itself. For the power supply Vs, the resistor 66, the micro G switch 65, the PMOS switch 6
7, the capacitor 68 and the NMOS power element 69 are connected as shown. A power element 71 and an inflator 74 are connected in series to the power element 69, and resistors 72 and 73 are connected in parallel to each power element. The resistors 72 and 73 are used for self-diagnosis of the operating state of the inflator 74 by passing a minute current through this portion. Now, when the acceleration exceeds a predetermined value, the micro G switch 65 detects this, and the movable contact and the fixed contact are turned on. Then, the potential at the point A decreases and the switch 6
7 is turned on, and then the potential at the point B is increased to turn on the power element 69. At this time, when the automobile has a collision and the output signal from the crash sensor (not shown in the figure) is processed and detected by the microcomputer 70, the power element 71 is turned on. When the power elements 69 and 71 are turned on at the same time, the inflator 74 is ignited to activate the airbag and protect the occupant. Note that it is not easy for the micro G switch to keep the switch on for a long time even after the acceleration becomes zero. In this case, the power element 69 can be substantially turned on even after the micro G switch 65 is turned off by the capacitor 68. That is, even after the acceleration becomes zero, the state in which the micro G switch 65 is apparently turned on can be maintained for a certain period. By doing so, the reliability of the airbag system can be improved.

FIG. 12 shows a method of mounting the integrated ignition device using the micro G switch according to the present invention. Micro G switch 65 on the substrate 75 such as ceramics,
A signal processing circuit 78 including a power element 69 and a resistor 66, a switch 67, a capacitor 68 and the like in the previous figure is arranged. A cap 77 is joined to the upper part of the substrate 75 to hermetically seal a space 76 containing the micro G switch 65 and the like. The integrated ignition device is electrically connected to an external power source or an inflator via pads 79 and 80 provided on the substrate 75. As a result, it is possible to provide an integrated ignition device that is small in size, suitable for mass production, and has high performance and high reliability.

Another embodiment of the micro G switch according to the present invention is shown in FIG. This drawing shows an embodiment in which a second movable mass and a beam are arranged between the movable mass and the beam. That is,
The second movable mass 81 and the second beam 83 are provided between the movable masses 82 supported by the beam 4. After the movable contact 14 formed on the surface of the movable mass 82 is turned on by the acceleration, the beams 4 and 83 are further deformed, and eventually the entire surface of the movable mass 81 is brought into contact with the lower surface of the glass plate 1. By the damping effect of the surface of the movable mass 81 and itself,
Even after the acceleration becomes zero, the movable contact can be kept on for a long time.

Another embodiment of the micro G switch according to the present invention is shown in FIG. This figure shows a micro G switch in which the gate electrode of a MOS switch is movable and a composite micro G switch in which a power element portion is integrated on the same silicon plate. An n + region is formed on the surface of the p-type silicon plate 84 passivated with the thermal oxide films 150 and 151 by a diffusion or ion implantation method to form the source and drain parts of the power element and the micro G switch. And
Reference numerals 86, 87 and 88 denote a source electrode, a drain electrode and a gate electrode of the power element part, respectively. Also 89, 9
Reference numerals 0 and 91 respectively denote a source electrode, a drain electrode and a gate electrode of the micro G switch section. The value of the current flowing through the power element part is several to several tens of amperes, whereas the value of the current flowing through the micro G switch part is so small that it can be ignored. The gate electrode 91 of the micro G switch unit is a movable mass supported by the beam 92. The beam 92 is firmly fixed on the thermal oxide film 150 at its end portion 152. When the acceleration orthogonal to the surface of the silicon plate 84 acts, the size of the void 153 between the gate electrode 91 and the thermal oxide film 150 becomes smaller. When the dimension value of the gap 153 becomes a predetermined value or less, the source electrode 89 and the drain electrode 90 of the micro G switch are turned on. Then, as described in FIG. 11, the source electrode 86 and the drain electrode 87 of the power element portion can be turned on. The micro G switch section and the power element section are hermetically housed in the space 94 by the cap 85 joined to the upper portion of the silicon plate 84.
The composite micro G switch is electrically connected to an external signal processing circuit via a pad 93 formed on the silicon plate 84. As a result, a micro G switch having a small size, suitable for mass production, high performance and high reliability can be realized.

Another embodiment of the composite micro G switch according to the present invention is shown in FIG. The micro G switch of this embodiment has a structure in which a mechanical switch section and an electronic MOS switch section are separated. On the thermal oxide film 150 of the silicon plate 84, the movable mass 98 supported by the beam 99 firmly fixed at the end portion 100 is formed by a sacrifice layer etching method. The mechanical switch section includes a movable mass 98 supported by the beam 99, a movable contact 97 formed on the movable mass 98, and a fixed contact 96 arranged so as to face the movable contact 97. The electronic MOS switch section includes a source electrode 89, a drain electrode 90 and a gate electrode 95. The gate electrode 95 and the fixed contact 96 are formed of the thermal oxide film 15
0 is electrically connected, and when the composite micro G switch receives the acceleration and the movable contact 97 and the fixed contact 96 come into contact with each other, the potential of the gate electrode 95 increases to turn on the MOS switch section. As described above, the movable mass 98 is previously supplied with a high voltage from the power supply through the beam 99. When the movable contact 97 and the fixed contact 96 come into contact with each other, the MOS switch is turned on to operate the power element section. Thus, by forming a MOS switch on the silicon plate 84 and electrically connecting the gate electrode 95 of this MOS switch and the fixed contact 96, the current flowing through the mechanical switch unit is limited to a minute value. You can The function of limiting the current flowing through the switch to a certain value or less is formed in the silicon plate, and the movable contact and the fixed contact are made of a metal material with a high melting point to ensure complete welding between the movable electrode and the fixed electrode. A highly reliable composite micro G switch can be obtained. Further, the function of keeping the ON state of the MOS switch for a long time even after the acceleration becomes zero can be easily integrated in the silicon plate 84.

Another embodiment of the composite micro G switch according to the present invention is shown in FIG. The micro G switch of this embodiment also has a structure in which a mechanical switch section and an electronic MOS switch section are separated. A fixed electrode 101 is arranged so as to face the surface of the movable mass 98 supported by the beam 99, and the fixed electrode 101 and the gate electrode 95 of the MOS switch part are electrically connected indirectly or directly on the thermal oxide film 150. Have a good connection. The size of the space 154 between the movable mass 98 and the fixed electrode 101 changes according to the acceleration acting on the micro G switch, and the capacitance of the space 154 changes. Then, when acceleration acts on the micro G switch, the potential of the gate electrode 95 portion rises to turn on the MOS switch portion. In this way, by forming a MOS switch on the silicon plate and making the conductor portion (fixed electrode) electrically connected to the gate electrode portion of this MOS switch face the movable mass, the potential of the gate electrode portion is increased according to the acceleration. Changes and the MOS switch turns on,
A highly sensitive composite micro-G switch that operates at very low acceleration is obtained. The fixed electrode may be a region diffused to the silicon plate 84 so as to face the movable mass 98.

A mounting method of the composite micro G switch according to the present invention is shown in FIG. In this embodiment, the composite micro G switch 102 (described in FIGS. 14 to 16) in which the micro G switch part and the power element part are integrated in the same silicon plate can be mounted together with the crash sensor 103 in the same package. It was done like this. The composite micro G switch 102 and the crash sensor 103 are adhered to the ceramic substrate 113 with adhesive materials 104 and 105. Next, the structure of the crash sensor 103 will be briefly described. The silicon plates 106, 107 and 108 are laminated in layers via insulators 109 and 110 such as thermal oxide films, and a movable mass 111 supported by a beam is formed inside by fine processing. The acceleration at the time of a crash is detected in an analog manner from the change in the electrostatic capacitance between the movable mass 111 and the silicon plates 106 and 108 arranged above and below. Cap 11 on the ceramic substrate 113
The two are bonded with an adhesive 114 to hermetically seal the periphery of the switch and the sensor. Then, it is surface-mounted on the module substrate 115 of the airbag system using the solder layer 117 via the conductive layer 116 of the ceramic substrate 113. By allowing it to be mounted in the same package with the crash sensor, the size of the control module for the airbag system can be reduced.

Another embodiment of the composite micro G switch according to the present invention is shown in FIG. In this embodiment, the silicon plate 8
The crash sensor 121 is integrally integrated with the composite micro G switch 102 described with reference to FIGS. 14 to 16. By etching the thermal oxide film 150 of the SOI substrate as a sacrificial layer, a void 118 is formed below the movable mass 120. The fixed end 119 of the beam (not shown in the figure) supporting the movable mass 120 is firmly fixed on the thermal oxide film 150. This is a crash sensor that detects the acceleration at the time of crash in an analog manner from the change in the electrostatic capacitance between the movable mass 120 and the silicon plate 84. By integrating the integrated micro G switch together with the crash sensor on the same silicon plate, the size of the control module for the airbag system can be further reduced.

[0024]

As described above, according to the present invention, the size of the micro G is small, suitable for mass production, and has high performance and high reliability.
You get a switch.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a micro G switch according to the present invention.

FIG. 2 is a diagram showing another embodiment of the micro G switch according to the present invention.

FIG. 3 is a diagram showing another embodiment of the micro G switch according to the present invention.

FIG. 4 is a diagram showing another embodiment of the micro G switch according to the present invention.

FIG. 5 is a diagram showing another embodiment of the micro G switch according to the present invention.

FIG. 6 is a diagram showing a mounting method of a micro G switch according to the present invention.

FIG. 7 is a diagram showing another embodiment of the micro G switch according to the present invention.

FIG. 8 is a diagram showing a schematic plan view of the micro G switch shown in the previous figure.

FIG. 9 is a diagram showing another embodiment of the micro G switch according to the present invention.

FIG. 10 is a diagram showing a schematic plan view of a movable part of the micro G switch shown in the previous figure.

FIG. 11 is a diagram showing an example of application to an integrated ignition device according to the present invention.

FIG. 12 is a diagram showing a method of mounting the integrated ignition device according to the present invention.

FIG. 13 is a diagram showing another embodiment of the micro G switch according to the present invention.

FIG. 14 is a diagram showing an embodiment of a composite micro G switch according to the present invention.

FIG. 15 is a view showing another embodiment of the composite micro G switch according to the present invention.

FIG. 16 is a diagram showing another embodiment of the composite micro G switch according to the present invention.

FIG. 17 is a diagram showing a method of mounting the composite micro G switch according to the present invention.

FIG. 18 is a view showing another embodiment of the composite micro G switch according to the present invention.

[Explanation of symbols]

1, 3 ... Glass plate, 2, 32, 34, 84, 106, 1
07, 108 ... Silicon plate, 4, 45, 56, 83, 9
2, 99 ... Beam, 5, 46, 57, 81, 82, 9
8, 111, 120 ... Movable mass, 6, 7, 20, 38,
39, 40 ... through holes, 8, 9, 12, 21, 21
3, 27, 41, 42, 43, 55 ... Wiring lead portion, 1
0, 11 ... Metal thin film, 13, 25, 36, 37 ... Solid column, 14, 49, 49a, 62, 62a, 97 ... Movable contact, 15, 48, 48a, 61, 61a, 96 ... Fixed contact, 16, 35 ... Frame part, 17, 18, 118, 153
154 ... Void, 19 ... Minute convex portion, 22, 26 ... Electrode,
24 ... Insulator protrusion, 28 ... Air circulation groove, 29, 30,
117 ... Solder layer, 31 ... Module, 33, 109, 1
10, 150, 151 ... Thermal oxide film, 44, 53 ... Movable part, 47, 50, 63 ... Fixed part, 51, 77, 85, 1
12 ... Cap, 52, 76, 94 ... Space, 54, 7
9, 80, 93 ... Pads, 58, 59 ... Projections, 60 ... Projections, 64, 119 ... Fixed end, 66 ... Resistance, 65, 20
0 ... Micro G switch, 66, 72, 73 ... Resistor, 6
7 ... Switch, 68 ... Capacitor, 69, 71 ... Power element, 70 ... Microcomputer, 74 ... Inflator, 75, 115 ... Board, 78 ... Signal processing circuit, 86,
89 ... Source electrode, 87, 90 ... Drain electrode, 88,
91, 95 ... Gate electrode, 101 ... Fixed electrode, 102 ...
Composite micro G switch, 103 ... Crash sensor, 104, 105, 114 ... Adhesive material, 113 ... Ceramics substrate, 116 ... Conductive layer, 152 ... End part.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Terumi Nakazawa 2520 Odaiba, Hitachinaka-city, Ibaraki Pref.

Claims (28)

[Claims] 1. A beam obtained by finely processing a silicon plate and a movable mass, the movable mass is a movable contact supported by the beam and provided on a part of the movable mass, and is provided on a glass plate facing the movable contact. And the center of gravity of the movable mass is arranged on the central axis of the beam, and the beam, the movable mass, the movable contact and the fixed contact are in an airtight space obtained by anodic bonding the silicon plate and the glass plate. A micro G switch characterized by being arranged. 2. The silicon plate according to claim 1, wherein when the silicon plate and the glass plate are anodically bonded, the silicon plate is electrically connected to the portion of the glass plate facing the movable mass so that the movable mass does not bond to the glass plate. A micro G switch characterized by forming a connected metal thin film. 3. The micro G switch according to claim 1, wherein a movable contact is provided on the convex portion of the movable mass. 4. A micro G switch according to claim 1, wherein a pre-bias electrode is formed on the glass plate so as to face the surface of the movable mass opposite to the surface on which the movable contact is provided. 5. The micro G switch according to claim 1, wherein an electrode for self-diagnosis is formed on a glass plate so as to face a surface of the movable mass on which the movable contact is provided. 6. The micro G switch according to claim 1, wherein movable contacts are provided on both sides of the movable mass, and fixed contacts are arranged facing the movable contacts. 7. A micro G switch according to any one of claims 1 to 6, wherein an air circulation groove or air circulation hole for air damping is provided on the surface of the movable mass. 8. A micro G switch according to claim 1, wherein each switch pad is provided on the surface of the glass plate through a through hole formed in the glass plate. 9. The micro G switch according to claim 7, wherein the movable contact and the fixed contact are made of a refractory metal material such as Au, Pt, or Pd. 10. The micro G switch according to claim 7, wherein each switch pad is directly mounted on a conductive portion of a substrate on which the switch is mounted. 11. A beam and a movable mass obtained by finely processing an SOI semiconductor substrate, a movable contact provided on the movable mass, the movable mass being supported by the beam, and a fixed contact provided on the semiconductor substrate facing the movable contact. And a beam, a movable mass, a movable contact and a fixed contact arranged in an airtight space obtained by anodic bonding on the SOI semiconductor substrate. 12. The micro G according to claim 11, wherein the movable mass is supported by at least one beam, and the movable contact and the fixed contact are at least one set.
switch. 13. The micro G switch according to claim 12, wherein the shape of the semiconductor substrate at the portion where the movable mass or the fixed contact is provided is comb-shaped. 14. A micro G switch according to claim 12, wherein a semiconductor substrate is finely processed to provide electrodes for self-diagnosis. 15. A micro G switch according to claim 12, wherein a semiconductor substrate is microfabricated to provide electrodes for pre-bias. 16. A micro G switch according to claim 11, wherein the movable contact and the fixed contact are made of a refractory metal material such as Au, Pt or Pd. 17. A semiconductor type power element section for igniting an inflator of an airbag system, a micro G switch section, and a signal processing circuit section for igniting the inflator when a collision signal of an automobile and the micro G switch is in an ON state. An integrated ignition device for an airbag system, characterized by being integrated on a substrate. 18. The integrated ignition device according to claim 17, wherein the power element section, the micro G switch section and the signal processing circuit section are held in an airtight space by a member bonded on the semiconductor substrate. 19. The micro G switch according to claim 17, wherein the semiconductor substrate has a function of limiting a current flowing through the switch portion. 20. The micro G switch according to claim 17, wherein the semiconductor substrate is provided with a function of ensuring the duration of an apparent switch-on state. 21. The micro G switch according to claim 1, wherein a second movable mass and a second beam are arranged between the beam and the movable mass. 22. A micro G switch composed of a movable gate supported by a beam and a power element are integrated on a semiconductor substrate, and the member bonded to the semiconductor substrate hermetically seals the micro G switch section and the power element section. An integrated micro G switch characterized by being held in space. 23. A beam obtained by finely processing silicon, a movable mass, a movable contact provided on a part of the movable mass, a fixed contact provided on the semiconductor substrate so as to face the movable contact,
A micro G switch comprising a MOS switch formed on the semiconductor substrate, wherein the fixed contact is electrically connected to a gate electrode of the MOS switch. 24. A beam and a movable mass obtained by finely processing silicon, a fixed electrode provided on a semiconductor substrate facing the movable mass, and a MOS switch formed on the semiconductor substrate, wherein the fixed electrode is the A micro G switch which is electrically connected to a gate electrode of a MOS switch. 25. A beam obtained by finely processing silicon, a movable mass, a region opposed to the movable mass, diffused into a supporting substrate of an SOI substrate, and a MOS formed on the supporting substrate.
A micro G switch comprising a switch, wherein the diffusion region is electrically connected to a gate electrode of the MOS switch. 26. A composite micro G switch, characterized in that a semiconductor type crash sensor and a micro G switch part are hermetically mounted in a ceramic package. 27. A composite micro G switch characterized in that a semiconductor crash sensor and a micro G switch are integrated on the same silicon plate. 28. A composite micro G switch comprising a semiconductor crash sensor, a micro G switch and a power element integrated on the same silicon plate.