This invention relates to an electromechanical switch, more particularly to a contact structure for electromechanical switch. The contact structure includes a PCB based construction and a moving contact to allow many kinds of actuations and provide great switch characteristics, such as high isolation and low insertion loss, in the applicable range from DC to microwave.
The electronic signal transmission speed required to be processed is growing fast with the technology progress, so that the control switches or relays are required to be capable of processing signals at 1 GHz or higher frequency. The electromechanical switches or relays are for connecting or disconnecting current or circuitry with a mechanical design. The traditional contact structure of electromechanical switches is only capable of transmitting DC or extremely low frequency signals. If a processing device for high frequency signals desires to be added to the traditional contact structure with mechanical design, it will encounter problems such as large-scale cost increase and difficulties in mass production.
The MEMS switch or relay is used for resolving the problems mentioned above. In brief, it is fabricated on the silicon wafer using semiconductor technology with a potential of mass production. The micro design is capable of minimizing the volume of the switches or relays. The typical MEMS switch 5, as shown in
The MEMS switch is very small, so that the charged dielectric medium and effects of static friction always interfere with the stable actuation and release. Low insertion loss and high isolation both are acquired while the MEMS is used in the transmission of high frequency electronic signals, and will limit the gap between the electrodes 11 and 14. Therefore, the MEMS switch is restricted while being used for transmitting the high frequency electronic signals.
In addition, the MEMS is fabricated with semiconductor technology, and the processes include repeatedly oxidizing, depositing, transferring, and etching. The processes are complicated and the steps are numerous. If one of the processes is not properly performed, the entire element must be reworked, resulting in increased manufacturing time and cost.
The objective of this invention is to provide a contact structure for electromechanical switch, which provides stable switch characteristics, has low insertion loss while ON, and has high isolation while OFF.
The contact structure of this invention works with low driving voltage.
The contact structure of this invention allows many kinds of actuations, such as electrostatic force, electro-magnetic force, piezoelectric effect, or heat effect.
The contact structure of this invention can be applied to the switch or relay with the range from DC to microwave, and is capable of processing signals at a frequency of 1 GHz or higher.
The contact structure of this invention uses a PCB structure and is suitable for low cost mass production. Compared to traditional MEMS switch, the switch of this invention has lower manufacturing cost and simpler manufacturing method.
The contact structure of this invention is capable of minimizing the volume of the MEMS switch.
The PCB and moving contact are designed in the contact structure of this invention. Although the PCB has already been used in RF switch and thin film switch, the switch of this invention still possesses many characteristics to make it different from the PCB base in RF switch and thin film switch, which include:
Other features or advantages of the present invention will be apparent from the following drawings and detailed description of several embodiments, and also from the appending claims.
The specific examples below are to be construed as merely illustrative, and not limitative, of the remainder of the disclosure in any way whatsoever. Without further elaboration, it is believed that one skilled in the art can, based on the description herein, utilize the present invention to its fullest extent. Further, any mechanism proposed below does not in any way restrict the scope of the claimed invention.
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The basic layer 21 is made of a rigid material but not limited to insulation material, such as FR4, or a material capable of responding to a certain range of microwave frequency, such as RO4003 high frequency circuit board material. A lower surface of the basic layer 21 has a grounding structure (not shown) which is formed by metalizing the lower surface of the basic layer 21. Signal traces are set on an upper surface of the basic layer 21 by printed circuit technology to form static contacts 211.
The spacing layer 22 is arranged on the upper surface of the basic layer 21. The material of the spacing layer 22 is not limited to any PCB materials, such like kapton, typical FR4, or solid bonding film made from acrylic with a predetermined thickness. The spacing layer 22 includes a window 221 to expose the static contacts 211 of the basic layer 21 through the spacing layer 22.
The top layer 23 is arranged on the upper surface of the spacing layer 22, and is made from a flexible circuit board material. Metal traces are set on a lower surface of the top layer 23 to form moving contacts 231. The flexible circuit board surrounding the moving contacts 231 is machined by specifically cutting to form a nick 232, so that a floating area 233 surrounds the moving contacts 231. The floatability is meant by that the floating area 233 can be moved downwardly while force is applied and moved upwardly to become flat when the force is released.
Finally, the basic layer 21, the spacing layer 22 and the top layer 23 are stacked together, as shown in
The static contacts 211 and the moving contacts 231 are designed as metal conducting paths of geometric shape with definition based on their applicable field. Therefore, the layouts of the paths of the static contacts 211 and the moving contacts 231 are decided according to the performance of the switch or relay. That will result in a much wider applicable field from DC to microwave for the contact structure 20 of the invention, which is capable of processing signals at a frequency of 1 GHz or higher, and make it possible to perform a low insertion loss.
The static contacts 211 and the moving contacts 231 have specific impedance individually, which normally is of 50Ω. Micro strips possess good impedance control and are suitable for passing the high frequency signal, therefore suitable for the static contacts 211 and the moving contacts 231. It is capable of narrowing the width of the metal conducting paths or the micro strip to reduce the phenomenon of overlapping contact, and is further capable of making the isolation much higher while the switch is OFF. Besides, the impedance variation resulted from the decrease in the overlapping contact of conductive pathway should be considered. Therefore, a compensation structure is set along the metal conducting paths to compensate the impedance variation. In this embodiment, a tuning circuit arranged adjacent to the layouts of the static contacts 211 and the moving contacts 231 is used to carry out the compensation structure.
The gap between the static contacts 211 and the moving contacts 231 is defined by the thickness of the spacing layer 22 and the electric power requirement for driving the actuation of the contact structure 20. However, a narrow gap is preferable to make sure that the moving contacts 231 contacts the static contacts 211 and the driving power is low.
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The packaged embodiments of contact structure 20 and actuating device 30 by conventional semiconductor packaging technique are illustrated in
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No matter what the package technology is, the design of the leads must be considered so that it does not result in the interference of the impedance matching of the contact structure 20. Besides, the performance of processing high frequency signal must also be kept.
In summary, the core of this invention is using PCB process and moving contact to form the contact structure of the electromechanical switch. It minimizes the volume of the electromechanical switch, lowers the production and manufacturing cost of the electromechanical switch, allows many kinds of actuations, matches many kinds of actuating devices, and provides the switch with good switch characteristics, such as high isolation and low insertion loss. And the suitable range is from DC to microwave.
From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, those other embodiments should also be within the scope of the claims.
Number | Date | Country | Kind |
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100119622 | Jun 2011 | TW | national |