Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H61/00—Electrothermal relays
  • H01H61/02—Electrothermal relays wherein the thermally-sensitive member is heated indirectly, e.g. resistively, inductively
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/0036—Switches making use of microelectromechanical systems [MEMS]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H1/00—Contacts
  • H01H1/0036—Switches making use of microelectromechanical systems [MEMS]
  • H01H2001/0042—Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H61/00—Electrothermal relays
  • H01H2061/006—Micromechanical thermal relay

Definitions

• the present invention relates to a micro actuator arrangement with a substrate with a first thermomechanical micro actuator and a second thermomechanical micro actuator, the first thermomechanical micro actuator being deflected essentially parallel to the surface of the substrate during thermal excitation.
• the micro actuator arrangement is particularly suitable for use as a micro relay.
• Microrelays are increasingly replacing conventional electromechanical relays, since they can be manufactured at lower costs and with less space and, due to their size, also achieve shorter switching times. These micro-relays are currently usually implemented on the basis of micro-actuators that work according to the electrostatic principle. These electrostatic microrelays are, however, characterized by relatively small travel ranges and small actuating forces of the microactuators, which on the one hand leads to problems with regard to the dielectric strength of the microrelay and on the other hand to problems due to increased contact wear.
• thermomechanical microactuators which are used in other areas of microsystem technology, are characterized above all by the generation of comparatively large actuating forces and actuating paths with moderate power consumption at the same time.
• microsystem technology they are used primarily for the construction of micro-actuators, where the greatest possible actuating forces and travel are important.
• An example of this is the use in micro valves. Since electrical power in the range of a few 100 mW is generally required for the operation of thermal microactuators, thermal drives have so far primarily been used for the construction of individual control elements.
• thermomechanical microactuators A particular disadvantage of thermomechanical microactuators, however, is that a thermomechanical microactuator must be continuously heated by supplying energy in order to maintain its deflected state (ON state) brought about by thermal excitation. For this reason, thermomechanical microators have not been used in microrelays, as in a large number of other applications, or have only been used in exceptional cases.
• US 5,909,078 shows an example of a microactuator arrangement with thermomechanical microactuators according to the preamble of claim 1.
• a single or a plurality of bar-shaped elements arranged next to one another are used as the microactuator, which are clamped parallel to a substrate surface at both ends on the substrate and in an egg -
• a preferred direction are biased parallel to the substrate surface.
• By heating the bar-shaped elements they expand in the clamped state, so that a deflection in the preferred direction results parallel to the substrate surface.
• This deflection movement can be used, for example, to open or close a valve opening in the substrate.
• Even the thermomechanical microactuators of this publication cannot be used without the above disadvantages in a microrelay in which individual switching states have to be held for a long time.
• thermomechanical microrelay which is described in J.-Y. Lee et al. , "A characteristicization of thermal parameters of thermally driven polysilicon microbridge actuators using electrical impedance analysis", Sensors and Actuators A75 (1999), 86-92.
• a bridge-shaped polysilicon membrane is deflected by heating perpendicular to the substrate surface in order to connect electrical contacts. To keep this connection, however, constant energy supply is required.
• thermomechanical actuators of the same design
• a deflection of the two actuators parallel to the substrate surface is brought about.
• One of the actuators can be kept currentless in a certain position via a mechanical locking mechanism, a lateral hooking with the second actuator.
• the lock can be released again by actuating the second actuator.
• the object of the present invention is to provide a further microactuator arrangement which enables switching between at least two switching states with a large actuating force and a large actuating range, the respective switching states being able to be kept without power.
• microactuator arrangement according to claim 1.
• Advantageous configurations of the micro actuator arrangement are the subject of the subclaims.
• the present micro actuator arrangement consists of a substrate with at least two thermomechanical micro actuators.
• a first thermomechanical microactuator is arranged on the substrate in a manner known from the prior art, with a thermal excitation deflecting it essentially parallel to the surface of the substrate, that is to say executing its actuating movement essentially parallel to the surface.
• the second thermomechanical microactuator is designed on the one hand in such a way that it is deflected essentially perpendicularly to the surface of the substrate in the event of thermal excitation, ie it carries out its actuating movement essentially perpendicularly to the substrate surface.
• the second thermomechanical microactuator is arranged relative to the first thermomechanical microactuator in such a way that a section of the first thermomechanical microactuator thermal excitation extends to below a section of the second thermomechanical microactuator - in the deflected state. Since the second thermomechanical microactuator performs an actuating movement substantially perpendicular to the substrate surface, a section of the first thermomechanical microactuator is thus in a deflected state between a section of the second thermomechanical microactuator and the substrate surface, so that this section of the first thermomechanical microactuator when the second thermomechanical microactuator is pinched by the latter.
• thermomechanical microactuators thus enables the switching state (ON-
• thermomechanical microactuator State of the first thermomechanical microactuator to keep powerless.
• both thermomechanical microactuators are first switched on, i.e. thermally excited so that a first section of the first thermomechanical micro actuator moves under a second section of the second thermomechanical micro actuator.
• the second thermomechanical microactuator is then switched off and thereby clamps the first section of the first thermomechanical microactuator. If this is then also switched off by interrupting the heat supply, it remains in the deflected position, since it is held in this position by the clamping action of the switched off second thermomechanical microactuator.
• This holding position is determined on the one hand by the friction between the two microactuators and on the other hand by the high restoring force with which the second thermal kroaktor takes its rest position, enables. In this way, the deflected state of the first thermomechanical microactuator is maintained without further energy supply, that is to say without power. To release this stop position, it is only necessary to briefly switch on the second thermomechanical microactuator, as a result of which the stop position is released and the first thermomechanical microactuator returns to its rest position (OFF state), in which it also remains without energy supply.
• thermomechanical microactuators This property of the microactuator arrangement according to the invention, of being able to keep two switching states without power using thermomechanical microactuators, opens up the possibility of large ones
• thermomechanical micro actuators can also be used in areas for which they were not previously suitable.
• the present micro actuator arrangement is particularly suitable for use in micro relays, but can of course also be used for other applications, such as for micro valves.
• the use of the present micro actuator arrangement makes it possible, particularly when used in micro relays, to combine comparatively large travel ranges with a relatively large pressure force on the contacts to be bridged.
• the first thermomechanical actuator hereinafter also referred to as the lateral actuator, can be designed in such a way that it enables strokes or travel ranges of 50-80 ⁇ m.
• microactuator arrangement not only two but also other switching states can be realized and kept powerless with this arrangement.
• This configuration enables a large number of switching connections in a micro relay equipped with the microactuator arrangement according to the invention.
• Another preferred embodiment of the present microactuator arrangement is characterized in that the two microactuators get caught in one another when the holding position is taken up. This allows a very safe stopping position, in which the friction between the two actuators is irrelevant.
• This interlocking can be realized in that the two sections of the lateral actuator and the z-actuator lying one above the other in the holding position mesh, for example in that one of the two sections has a recess into which an elevation of the other of the two sections engages.
• other geometrical configurations are also conceivable which lead to a corresponding interlocking or to a corresponding interlocking. Those skilled in the art are familiar with such designs from many different LO _ ⁇ _o H- 1 H->
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• the substrate can be used.
• a mechanical coupling of different lateral actuators is also possible, as is known from the US document mentioned in the introductory part.
• the conductor tracks or contact areas to be switched, that is to be electrically bridged are applied to the substrate.
• corresponding contact bridges made of a highly conductive material are provided on the underside of the lateral actuator.
• the actuator itself or the bar-shaped elements of the actuator can consist of other materials.
• nickel is preferably used as the material for the bar-shaped elements, since it has good thermomechanical properties and is suitable for building up the elements in the required dimensions using known means of microstructure technology.
• the electrically conductive contact bridges and the heating line layer are additionally insulated from the nickel by an intermediate layer.
• thermomechanical microactuators on a substrate can be found in the specialist literature at any time. This is usually a combination of photolithography, galvanic deposition and etching.
• FIG. 1 schematically shows an example of a micro actuator arrangement according to the invention.
• Fig. 2 shows another example of a micro actuator arrangement according to the invention in use as a micro relay.
• FIG. 1 shows a three-dimensional view of a micro actuator arrangement according to a first exemplary embodiment.
• the micro actuator arrangement consists of the substrate 1, a semiconductor substrate, on which a lateral micro actuator 3 and a z actuator 4 are arranged.
• the lateral actuator 3 is composed of four bar-shaped elements 7, each of which is anchored to the substrate 1 on one side.
• a plate-shaped bracket 9 is attached to these bar-shaped elements and extends in the direction of the deflection, that is, in the direction of the z-actuator 4.
• the lateral actuator 3 can be seen in the figure in the deflected state. In the idle state, it is located above the indicated depression 11 in the substrate surface, which is generated during the manufacturing process when the beam-shaped elements 7 are undercut.
• the bar-shaped elements 7 are provided with heating line layers (not shown in the figure), which are supplied with current via corresponding connection pads 12.
• the bar-shaped elements have dimensions of typically about 1 mm in length, 5-10 ⁇ m in width and 15-20 ⁇ m in height.
• the z-actuator 4 is also composed of a bar-shaped element 8 which is clamped on the substrate 1 on both sides. This z-actuator 4 is designed in the form of a bridge actuator. In this case too, the bar-shaped element 8 is provided with a corresponding heating line layer, not shown, which is supplied with current via connection pads 12.
• a plate-shaped arm 10 is also provided on the z-actuator 4 and extends in the direction of the lateral one
• Actuator 3 extends. Both arms 9 and 10 can interlock with one another by a corresponding design, as is shown in the enlarged area of FIG. 2.
• the bar-shaped elements 7 of the lateral actuator 3 are located above the recess 11, the bar-shaped element 8 of the z-actuator 4 lies on the substrate 1.
• both actuators are first put into operation.
• the lateral actuator 3 pushes its plate-shaped cantilever 9 below the z-actuator 4.
• the z-actuator is switched off first and lowers with its cantilever 10 onto the cantilever 9.
• a suitable hook-like structure prevents the lateral actuator 3 from being switched off a release of this contact.
• Both actuators are also initially switched on for the transition to the OFF state. This time, the lateral actuator 3 is switched off in front of the z-actuator 4.
• the figure 1 shows the microactuator arrangement in the ON state.
• the bar-shaped elements 7, 8 and the arms 9, 10 of the two actuators 3, 4 are made of nickel in this example.
• the heat conductor running below the bar-shaped elements is separated from this metallic structure by insulation layers.
• FIG. 2 shows a further example of a micro actuator arrangement according to the present invention when used as a micro relay.
• the substrate 1 and the two microactuators 3, 4 with the respective bar-shaped elements 7, 8 and the cantilevers 9, 10 can be seen.
• four conductor tracks 13 are arranged on the substrate 1, all of which - as can be seen in the enlarged view - are interrupted by a gap.
• Contact bridges 14 for closing the open contacts are located on the underside of the arm 9 of the lateral actuator 3. These contact bridges 14 can be formed from a highly conductive material such as gold, which is insulated from the material of the actuator. As a result, smaller lead resistances can be achieved in the relay.
• FIG. 13 shows the ON switching state of the microrelay, in which the contacts of the four lines are closed in different ways, as can be seen in the enlarged view.
• the high contact pressure of the contact bridges 14 on the lines 13 enables a long service life of the contacts.
• the high pressure force is generated by the restoring movement of the z-actuator 4, which presses on the lateral actuator 3.
• a geometrical arrangement of a possible hooking between the arm 10 of the z-actuator 4 and the arm 9 of the lateral actuator 3 can also be seen.
• a suitable metal such as nickel is recommended for the construction of the microactuators.
• good thermal conductivity of the bar-shaped elements can also be achieved, so that the switching times of the relay are approximately between 10 ms and 100 ms. Due to the very good electrical conductivity of the bar-shaped elements, direct use as a heating conductor is not possible in this case.
• a heating conductor layer is preferably attached to the actual actuator element, which of course must be insulated from the actual thermal actuator.

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• Micromachines (AREA)
• Thermally Actuated Switches (AREA)
• Medicines Containing Material From Animals Or Micro-Organisms (AREA)

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• 2000
  • 2000-03-29 DE DE10015598A patent/DE10015598C2/de not_active Expired - Lifetime
• 2001
  • 2001-03-16 US US10/239,989 patent/US6684638B2/en not_active Expired - Lifetime
  • 2001-03-16 EP EP01919213A patent/EP1269506B1/fr not_active Expired - Lifetime
  • 2001-03-16 JP JP2001571436A patent/JP4880167B2/ja not_active Expired - Lifetime
  • 2001-03-16 DE DE50112158T patent/DE50112158D1/de not_active Expired - Lifetime
  • 2001-03-16 WO PCT/DE2001/001040 patent/WO2001073805A1/fr active IP Right Grant
  • 2001-03-16 AT AT01919213T patent/ATE356420T1/de not_active IP Right Cessation

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