Micro-relay and method for manufacturing the same

Abstract: A thin plate-shaped substrate 21 comprised of a monocrystal is provided with a piezoelectric element 24, and both ends of a movable piece 20 whose one surface is provided with a movable contact 25 are fixed and supported to a base 11. Then, by curving the movable piece 20 via the piezoelectric element 24, the movable contact 25 is brought in and out of contact with a pair of fixed contacts 38 and 39 that face the movable contact. With this arrangement, a subminiature micro-relay having a mechanical contact mechanism that has a small resistance in turning on the contact and the desired vibration resistance, frequency characteristic and insulating property can be obtained.

Description: TECHNICAL FIELD The present invention relates to an electronic component such as micro-relays, and in particular micro-relays, matrix relays and micro-relay chips having contacts which are opened and closed by curving a movable piece constructed of a monocrystal thin plate-shaped substrate. BACKGROUND ART Conventionally, as an electronic component of the micro-relay chip, there has been the one proposed in Fig. 27 and Fig. 28 of Japanese Patent Laid-Open Publication No. HEI 7-299765. That is, the electronic component is a micro-relay obtained by wire-bonding the connecting electrodes of a micro-relay chip to the external terminals of a lead frame and molding them with resin. However, according to the above-mentioned electronic component, the whole body of the micro-relay chip has been molded with resin, and therefore, heat radiation is hard to be achieved. Therefore, due to the heat generation of the internal components, a malfunction tends to occur and the operating characteristics tend to vary. The above-mentioned electronic component is required to individually connect by wire bonding each connecting electrode of the micro-relay chip to each external terminal formed on the lead frame. For this reason, there is a great number of working processes, and the productivity is low. Furthermore, wire disconnection tends to be caused by vibration or the like, and this poses the problem that the reliability is low. In view of the aforementioned problems, the present invention has an object to provide an electronic component that can prevent the malfunction and the variation in operating characteristics due to heat and has high productivity and reliability. DISCLOSURE OF THE INVENTION In order to achieve the aforementioned object, the present invention is as defined in claim 1. According to the invention, the bottom surface of the base made of the silicon material having a heat conductivity higher than that of the glass material is exposed to the outside of the substructure. This allows the obtainment of an electronic component that is easy to radiate heat and able to prevent the occurrence of malfunction and a variation in operating characteristics. According to an embodiment, the internal component is electrically connected to an external terminal of the substructure via a through hole provided at the cover. According to this embodiment, there is no need for performing the individual electrical connection by wire-bonding in contrast to the prior art example, and the internal components are electrically connected to the external terminal of the substructure via the through hole provided at the cover. This arrangement makes simple connecting work, improves the productivity and improves the connection reliability. In particular, if the external terminal is formed of a lead frame, the working processes are further reduced in number, and the productivity is improved. According to a further embodiment, a heat sink is provided on the bottom surface of the base exposed to the outside of the substructure. According to this embodiment, the heat radiation efficiency via the heat sink for radiating heat is improved. This arrangement has the effect of more effectively preventing the malfunction due to heat and the variation in operating characteristics. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an electronic component according to an eighteenth embodiment of the present invention; and Fig. 2 is a cross sectional view of the electronic component shown in Fig. 46. An electronic component according to the embodiment will be described next with reference to the accompanying drawings of Fig. 1 and Fig. 2. The present embodiment is the application thereof to a micro-relay, which is constructed of a micro-relay chip 210, a box-shaped substructure 230 and a heat sink 240. The micro-relay chip 210 has built-in five contact mechanisms arranged parallel and is constructed of a base 211 made of a silicon monocrystal whose one surface is formed with a recess 212, a movable piece 213 whose both ends are fixed and supported to the opening edge portion of this base 211 and a cover 220 constructed of a glass wafer 221 integrated by anodic bonding with the base 211. The movable piece 213 is formed by laminating a driving layer 217 made of a metal material via an insulating film 216 on a heater layer 215 whose electrical resistance is increased by injecting boron or the like into the one side surface layer of a thin plate-shaped substrate 214 made of silicon monocrystal. Further, in the center portion of the insulating film 216 is arranged a movable contact 218 in an insulated state. The cover 220 is obtained by forming a pair of fixed contacts 223 and 224 on the bottom surface of the recess portion 222 provided on one side of the glass wafer 221. The fixed contacts 223 and 224 are led to the surface of the glass wafer 221 via an input/output use through hole (not shown) and electrically connected to input/output use external terminals 231 and 232 (the external terminal 231 located on the rear side is not shown in Fig. 46) of the substructure 230 via print wiring lines 225 and 226. Further, the glass wafer 221 is formed with through holes 227 and 228 for electrical connection to the heater layer 215 of the movable piece 213. The through holes 227 and 228 are electrically connected to driving use input terminals 233 and 234, which will be described later. A method for assembling the micro-relay of the present embodiment will be described next. First, a lead frame (not shown) is subjected to press processing so as to alternately punching the input/output use external terminals 231 and the driving use external terminals 233 in a comb-like shape and form the input/output use external terminals 232 and the driving use external terminals 234 in a similar manner. Then, an input/output use through hole (not shown) and the driving use through holes 227 and 228 of the microchip 210 are each positioned and electrically connected to the free end portions of the external terminals 231 and 234. Subsequently, the micro-relay chip 210 is held between a pair of metal molds, and the substructure 230 is integrally formed so that the bottom surface of the base 211 is exposed. Further, a plate-shaped heat sink 240 made of copper, aluminum, brass or the like having a great heat conductivity is fit in an annular stepped portion 235 formed on the upper surface of the substructure 230, and thereafter the external terminals 231 through 234 are cut from the lead frame. Thereafter, by bending the tip portions of the terminals, the assembling work is completed. The operation of the micro-relay having the above-mentioned construction will be described. If no current is flowing from the driving use external terminals 233 and 234 through the heater layer 215 of the movable piece 213, then the movable piece 213 remains flat, and the movable contact 218 is separated from the pair of fixed contacts 223 and 224. Subsequently, if a current flows through the heater layer 215 from the driving use through holes 227 and 228 via the driving use external terminals 233 and 234, then the heater layer 215 generates heat to thermally expand the thin plate-shaped substrate 214 and the driving layer 217. Then, the coefficient of thermal expansion of the driving layer 217 is much greater than the coefficient of thermal expansion of the thin plate-shaped substrate 214, and therefore, the movable piece 213 is curved toward the fixed contacts 223 and 224 side. Subsequently, the movable contact 218 comes in contact with the pair of fixed contacts 223 and 224, thereby making an electric circuit. If the aforementioned current is interrupted to stop the heat generation of the heater layer 215, then the thin plate-shaped substrate 214 and the driving layer 217 are cooled to contract. By this operation, the movable piece 213 is restored into the original state, and the movable contact 218 separates from the fixed contacts 223 and 224. Although the above-mentioned embodiment has been described on the basis of the external terminals 231, 232, 233 and 234 and the heat sink 240 constructed of members. However, the present invention is not always limited to this, and it is acceptable to simultaneously punch and bend the external terminals and the heat sink from the lead frame, position the micro-relay chip between the external terminals and the heat sink and thereafter mold them with resin. The above-mentioned embodiment has been described on the basis of the application to the micro-relay chip. However, the present invention is not always limited to this, and it is of course acceptable to apply the present invention to another electronic component chips whose internal component generates heat.

Claims: An electronic component comprising: (a) an electronic component chip (210) formed by connecting and integrating a cover (220) made of glass material with a base (211) made of a silicon material, said electronic component chip accommodating an internal component in an internal space thereof, (b) a substructure (230) resinmolded on the electronic component chip so that the cover (220) is coated with resin and a bottom surface of said base (211) is uncovered by resin. An electronic component as claimed in claim 1, wherein the internal component is electrically connected to an external terminal (231, 232, 233, 234) of the substructure (230) via a through hole (227, 228) provided in the cover (220). An electronic component as claimed in claim 1 or 2, wherein a heat sink (240) is provided on the bottom surface of the base (211) exposed to the outside of the substructure (230).

Inventors: FUJIWARA TERUHIKO, NAKAJIMA TAKUYA, SAKATA MINORU, SEKI TOMONORI, TAKEUCHI MASASHI, FUJIWARA, TERUHIKO, NAKAJIMA, TAKUYA, SAKATA, MINORU, SEKI, TOMONORI, TAKEUCHI, MASASHI, Fujiwara, Teruhiko Omron Corp 801 Minamifudodo-cho, Nakajima, Takuya, Omron Corp 801 Minamifudodo-cho, Sakata, Minoru, Omron Corp., 801, Minamifudodo-cho, Seki, Tomonori, Omron Corp 801 Minamifudodo-cho, Takeuchi, Masashi Omron Corp 801 Minamifudodo-cho
Applicants: OMRON TATEISI ELECTRONICS CO, OMRON CORPORATION
Application year: 1997
Main classification: H01H1
IPC codes: B81B7, H01H67, H01H1, H01H57, H01H59, H01H61