High frequency relay

Information

  • Patent Grant
  • 6340923
  • Patent Number
    6,340,923
  • Date Filed
    Wednesday, December 20, 2000
    24 years ago
  • Date Issued
    Tuesday, January 22, 2002
    22 years ago
Abstract
A high frequency relay comprises a contact base block having pairs of fixed contacts, contact members with movable contacts, and an electromagnet for moving the contact members to open and close the fixed contacts by the movable contacts. The contact base block comprises an injection-molded base having projections on its front surface, first metal films formed as the fixed contacts on top surfaces of the projections, second metal films formed as connection terminals for outside devices on a rear surface of the base, each of which corresponds to one of the first metal films, through holes each having a conductive material on its inner surface to make an electrical connection between one of the first metal films and the corresponding second metal film in the shortest distance, and a third metal film formed on the base to provide electrical isolation from the first and second metal films, which works as electromagnetic shield as well as a ground.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a high frequency relay.




2. Disclosure of the Prior Art




In the past, high frequency relays have been used to switch high frequency signals. For example, Japanese Patent Early Publication [KOKAI] No. 1-274333 discloses that a high frequency relay comprises a base, on which fixed contacts of gold-plated pins are mounted, a card having contact springs, a shield case having earth terminals manufactured by working a sheet metal, an electromagnet for moving the contact springs to open and close a pair of the fixed contacts by the contact spring, and a shield cover.




However, in this kind of high frequency relay, there are problems that variations in high frequency characteristic of the high frequency relay such as such as insertion loss, isolation loss and V.S.W.R. (reflection) occurs due to errors in working and assembling the relay components. On the other hand, when working and assembling the relay components with high accuracy, there is another problem of increasing the production cost of the high frequency relay in a large amount. In particular, as the relay becomes smaller in size, there is a limitation of working and assembling the relay components with high accuracy.




SUMMARY OF THE INVENTION




Therefore, a primary object of the present invention is to provide a high frequency relay capable of improving electromagnetic shield effect for preventing signal leakage and minimizing variations in high frequency characteristic resulting from steps of working and assembly the relay components.




That is, in the high frequency relay comprising a contact base block having at least one pair of fixed contacts, at least one contact member with a movable contact, and an electromagnet for moving the contact member to open and close the pair of fixed contacts by the movable contact, the contact base block comprises a base having at least one pair of projections on its top surface, which is an injection-molded article of an electrical insulating material; first metal films formed as the fixed contacts on top surfaces of the projections; second metal films formed as connection terminals for outside devices on the base, each of which corresponds to one of the first metal films; connecting means for making an electrical connection between each of the first metal films and the corresponding second metal film; and a third metal film at least formed on the top surface of the base to provide electrical isolation from the first and second metal films, which works as electromagnetic shield means.




By the way, to stabilize the high frequency characteristic of the high frequency relay, it is important to keep the assembly accuracy of relay components constant. In particular, it is required to accurately determine a distance between each of the fixed contacts and the corresponding connection terminal. In the past, when the relay components including the fixed contacts and the connection terminals are provided as separate parts, it is required to work and assemble each of the relay components with high accuracy, so that there is another problem of increasing the production cost.




In the present invention, since the first, second and the third metal films, which respectively function as the fixed contacts, connection terminals, and the electromagnetic shield means for preventing the leakage of the high frequency signals, are integrally formed on the injection-molded base, it is possible to readily and accurately control the distance between each of the fixed contacts and the corresponding connection terminal, and sharply reduce the total number of the relay components. According to these advantages, the present invention can stably provide the high frequency relay having a constant high frequency characteristic. In particular, as the high frequency relay becomes smaller in size, the present invention becomes to be more effective. Moreover, since the first metal films that are the fixed contacts are formed on the top surfaces of the projections, the movable contact can open and close the fixed contacts with reliability without contacting the third metal film.




In a preferred embodiment of the present invention, the high frequency relay further comprises a contact sub block for movably supporting the contact member, which comprises a subbase that is an injection-molded article of an electrical insulating material, and a fourth metal film formed on a surface of the subbase in a face to face relation with the top surface of the base when the contact sub block is mounted on the contact base block, so that the pair of fixed contacts are opened and closed by the movable contact in an electromagnetic shield space surrounded by the third and fourth metal films.




It is preferred that each of the second metal films is formed on a bottom surface of the base at a position opposed to the corresponding one of the first metal films. In this case, it is preferred that the connecting means is through holes each having a conductive layer on its inner surface, each of which is formed in the base to electrically connect one of the first metal films with the corresponding second metal film in the shortest distance.




It is further preferred that each of the projections has a first projection jutting from the top surface of the base and a second projection jutting from the first projection, and wherein each of the first metal films is formed on a top of the second projection and the third metal film is formed on side surfaces of the first projections. In addition, it is preferred that each of the projections has a rounded top, on which the first metal film is formed.




In addition, it is preferred that the high frequency relay comprises a first contact set of a first pair of fixed contacts and a first contact member used to switch a high frequency signal and a second contact set of a second pair of fixed contacts and a second contact member used to switch another high frequency signal, and wherein a shield wall for isolating the first contact set from the second contact set is integrally-molded with at least one of the base and the subbase.




In addition, it is preferred that the high frequency relay comprises a coil block for housing the electromagnet comprises an armature disposed between the contact member and the electromagnet and driven by energizing the electromagnet, and a motion of the armature is transferred to the contact member through a first spring member held by a spring holding portion integrally molded with the subbase.




Moreover, it is preferred that a coil block supporting portion for supporting the coil block and the spring holding portion are provided on a surface opposed to the surface having the fourth metal film of the subbase, and the contact member is attached to a through hole formed in the subbase with a second spring member such that the contact member receives a spring bias of the second spring member in a direction of spacing the movable contact from the fixed contacts, and the contact member can be moved against the spring bias of the second spring member by the first spring member pushed by the armature to close the fixed contacts by the movable contact.




It is also preferred that the high frequency relay comprises fifth metal films formed as coil electrodes for supplying electric power to the electromagnet on the base so as to provide electrical isolation from the first, second and third metal films.




Another object of the present invention is to provide a high frequency relay having the following structure. That is, in the high frequency relay comprising a contact base block having at least one pair of fixed contacts, at least one contact member with a movable contact, a contact sub block for movably supporting the contact member, and an electromagnet for moving the contact member to open and close the pair of fixed contacts by the movable contact, the contact base block comprises a base that is an injection-molded article of an electrical insulating material; first metal films formed as the fixed contacts on a top surface of the base; second metal films formed as connection terminals for outside devices on the base, each of which corresponds to one of the first metal films; connecting means for making an electrical connection between each of the first metal films and the corresponding second metal film; and a third metal film at least formed on the top surface of the base to provide electrical isolation from the first and second metal films, which works as electromagnetic shield means. In addition, the contact sub block comprises a subbase that is an injection-molded article of an electrical insulating material, and a fourth metal film formed on a surface of the subbase in a face to face relation with the top surface of the base when the contact sub block is mounted on the contact base block, so that the pair of fixed contacts are opened and closed by the movable contact in an electromagnetic shield space surrounded by the third and fourth metal films.




In the present invention, since the first, second and the third metal films, which respectively function as the fixed contacts, connection terminals, and the electromagnetic shield means for preventing the leakage of the high frequency signals, are integrally formed on the injection-molded base, and the fourth metal film is integrally formed as the electromagnetic shield means on the injection-molded subbase, there is an advantage that the electromagnetic shield space having a remarkable effect of preventing the signal leakage can be stably obtained in the high frequency relay by the third and fourth metal films even when the high frequency relay is small-sized.




These and still other objects and advantages will become apparent from the following detailed description of the invention.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a cross-sectional view of a high frequency relay according to a preferred embodiment of the present invention;





FIG. 2

is an exploded view of the high frequency relay;





FIGS. 3A

to


3


F are a front view, cross-sectional view taken along the line L, side view, rear view, cross-sectional view taken along the line M, and a side view of a contact base block of the high frequency relay, respectively;





FIGS. 4A

to


4


F are a front view, a cross-sectional view taken along the line P, side view, rear view, cross-sectional view taken along the line Q, and a side view of an injection-molded base of the contact base block, respectively;





FIG. 5A

is a partially perspective view of the contact base block, and

FIG. 5B

is a partially perspective view showing a modification of

FIG. 5A

;





FIGS. 6A

to


6


E are a front view, cross-sectional view taken along the line R, side view, rear view and a side view of a contact sub block of the high frequency relay, respectively;





FIG. 7A

is a top view of a first spring member, and

FIG. 7B

is a cross-sectional view of a subbase with the first spring members;





FIG. 8A

is a schematic view illustrating how to attach a contact member to a second spring member, and

FIGS. 8B

to


8


D are a front view, back view and a side view of the assembly of the contact member and the second spring member, respectively;





FIGS. 9A and 9B

are side views illustrating how to attach a coil block to the contact sub block, respectively;





FIGS. 10A

to


10


C are a front view, cross-sectional views taken along the lines S and T of a modification of the contact base block;





FIGS. 11A and 11B

are schematic cross-sectional views illustrating an insertion of a metal pin into a through hole of the contact base block;





FIGS. 12A and 12B

are schematic cross-sectional views illustrating a charge of a sealing compound into a through hole of the contact base block;





FIGS. 13A

to


13


D are a front view, side view, rear view and a side view of an injection-molded base of a contact base block according to another embodiment of the present invention, respectively;





FIGS. 14A

to


14


D are a front view, side view, rear view and a side view of the contact base block, respectively;





FIG. 15

is a partially perspective view of the contact base block;





FIGS. 16A

to


16


D are a front view, cross-sectional view taken along the line V, rear view and a cross-sectional view taken along the line W of an injection-molded subbase of a contact sub block according to another embodiment of the present invention, respectively;





FIGS. 17A

to


17


D are a front view, cross-sectional view taken along the line X, rear view and a cross-sectional view taken along the line Y of the contact sub block, respectively;





FIGS. 18A

to


18


F are schematic diagrams illustrating a method of manufacturing a contact base block of the high frequency relay according to a preferred embodiment of the present invention;





FIG. 19

is a plan view illustrating electrode members used for electroplating;





FIG. 20

is a wiring diagram for the electroplating;





FIG. 21

is another wiring diagram for the electroplating; and





FIGS. 22A

to


22


K are schematic diagrams illustrating a method of manufacturing a contact base block of the high frequency relay according to a further preferred embodiment of the present invention.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




A high frequency relay according to a preferred embodiment of the present invention is explained in detail referring to the attached drawings.




As shown in

FIGS. 1 and 2

, the high frequency relay is mainly composed of a contact base block


1


having plural pairs of fixed contacts, a contact sub block


2


for movably supporting contact members


21


with movable contacts


22


, an electromagnet


3


for moving the contact members to open and close the fixed contacts by the movable contacts, coil block


4


for supporting the electromagnet, and a relay case


5


.




As shown in

FIGS. 3A

to


3


F and


4


A to


4


F, the contact base block


1


comprises a base


10


, first metal films


70


formed as the fixed contacts on the base, second metal films


80


formed as connection terminals for outside devices on the base, each of which corresponds to one of the first metal films, and a third metal film


90


formed as a part of electromagnetic shield means on the base to provide electrical isolation from the first and second metal films.




The base


10


is an injection-molded article of an electrical insulating material having a rectangular case shape composed of a bottom wall


11


, side walls


12


jutting on the periphery of the bottom plate, and a top opening. The base


10


has a plurality of first projections


13


jutting from the bottom wall


11


, each of which is of a rectangular shape, and second projections


14


jutting from the top surfaces of the first projections, each of which is of a smaller rectangular shape. Each of the second projections has a through hole


16


extending from the top surface of the second projection to the rear surface of the base


10


. In this embodiment, the high frequency relay has a first contact set of the fixed contacts (upper


3


fixed contacts of

FIG. 3A

) and the contact members used to switch a high frequency signal and a second contact set of the fixed contacts (lower


3


fixed contacts of

FIG. 3A

) and the contact members used to switch another high frequency signal.




The numeral


17


designates through-holes extending from the front surface to the rear surface of the bottom wall


11


of the base


10


. The numeral


18


designates guide projections jutting from the top of side walls


12


, which are used to readily and accurately mount the contact sub block on the contact base block. Thus, since the base having the first and second projections


13


,


14


, through holes


16


,


17


, and guide projections


18


is formed by injection molding, it is possible to stably supply the base having a constant dimensional accuracy and reduce the number of the relay components. The through holes


16


,


17


may be formed by drilling after the injection molding.




Each of the first metal films


70


is formed on the top and side surfaces of the second projection


14


, as shown in FIG.


3


A. Since the first metal films


70


that are the fixed contacts are formed on the top surfaces of the second projections


14


, the movable contact


22


can open and close the fixed contacts with reliability without contacting the third metal film


90


. In this embodiment, the second projection


14


has a rounded rectangular top shown in

FIG. 5A

to prevent the occurrence of arc discharge between the fixed contacts, i.e., the first metal films


70


and the movable contact


22


. Alternatively, as shown in

FIG. 5B

, a cylindrical projection having a dome-shaped top may be adopted as the second projection


14


. In this case, it is preferred that the first and second projections are formed such that a center axis of the first projection


13


is in agreement with that of the second projection


14


.




Each of the second metal films


80


is formed on the rear surface of the base


10


, as shown in

FIG. 3D

, at a position opposed to the corresponding one of the first metal films


70


. In addition, a part of the second metal film


80


extends to the side wall


12


, to which desired outside devices such as printed wiring boards can be readily connected by soldering.




The third metal film


90


is formed the base


10


to extend from the front surface to the rear surface of the bottom wall


11


through the side walls


12


. The third metal film


90


is also formed on the side surfaces of the first projection


13


, so that the signal leakage can be more effectively prevented when the high frequency signal is transmitted through the through-hole connection between the fixed contact


70


and the corresponding connection terminal


80


. To electrically isolating the third metal film


90


from the first and second metal films


70


,


80


, an isolation area


50


having no metal film is formed around the first and second metal films. That is, each of the first metal films


70


is electrically isolated from the third metal film


90


by the isolation area


50


formed on the top surface of the first projection


13


around the second projection


14


.




Each of the first metal films


70


is electrically connected to the corresponding one of the second metal films


80


by a conductive layer plated on the inner surface of the through hole


16


in the shortest distance. Since a signal-flow path is shortened by the through-hole connection, it is effective to improve noise immunity. In this case, it is preferred that a center axis of the through hole


16


is substantially in agreement with that of the fist and second projections


13


,


14


. In addition, the third metal film


90


on the front surface of the bottom wall


11


is electrically connected to the third metal film on the rear surface of the bottom wall by conductive layers plated on the inner surfaces of the through holes


17


in the shortest distance. Since the electrical connection between the third metal films of the front and rear surfaces of the bottom wall


11


of the base


10


by the through holes


17


in the shortest distance provides the same potential at every position of the third metal film


90


, it is effective to further improve the high frequency characteristic of the relay. These through holes


16


,


17


are filled with a sealing material


62


,


64


such as conductive materials and synthetic resins to prevent the occurrence of condensation therein.




The numeral


100


designates fifth metal films formed on the opposite side walls


12


, which are used as coil electrodes for supplying electric power to the electromagnet


3


of the high frequency relay. The fifth metal films


100


are electrically isolated from the third metal film by the isolation area


50


. Since an electrical connection between the electromagnet


3


and the coil electrodes


100


formed on the base


10


can be achieved by use of wires and so on, it is useful to provide a further simplification of the assembly task for the high-frequency relay.




By the way, it is preferred that each of the first, second and third metal films


70


,


80


,


90


is composed of a copper layer as an undercoat, nickel layer as an intermediate layer, and a gold layer as an outer layer. In this case, it is particularly preferred that a thickness of the outer layer of the first metal films is greater than that of the second and third metal films. Alternatively, the second and third metal films may essentially consist of a copper layer as the undercoat, and a nickel layer as the outer layer. By reducing the amount used of gold, it is possible to improve cost performance of the high frequency relay.




As shown in

FIG. 2

, the contact sub block


2


comprises a subbase


30


, the contact members


21


with the movable contacts


22


, a fourth metal film


92


formed on a rear surface of the subbase, first spring members


42


for transferring a motion of an armature


52


driven by energizing the electromagnet


3


to the contact members


21


, and second spring members


45


each applying a spring bias to the contact member in a direction of spacing the movable contact


22


from the fixed contacts


70


.




As shown in

FIGS. 6A

to


6


E, the subbase


30


is an injection-molded article of an electrical insulating material, and has four rectangular through holes


32


, a pair of side walls


34


projecting from its front surface of the subbase and having bearing portions


35


for movably supporting the armature


52


in a seesaw fashion, spring holders


36


projecting from the front surface of the subbase, each of which is used to catch one end of the first spring member


42


, and stoppers


37


projecting from the front surface of the subbase between adjacent rectangular through-holes


32


, each of which restricts an excessive motion of the first spring member. The numeral


38


designates concaves formed in a rear surface of the subbase, into which the guide projections


18


are fitted when the contact sub block


2


is mounted on the contact base block


1


.




The fourth metal film


92


on the subbase


30


makes an electromagnetic shield space in cooperation with the third metal film


90


of the contact base block


1


. In this electromagnetic shield space, each of the pairs of fixed contacts


70


is opened and closed by the corresponding movable contact


22


. The formation of the electromagnetic shield space presents a remarkable effect of preventing the leakage of high frequency signal to the outside as well as an improvement in noise immunity. In this embodiment, when the pair of fixed contacts


70


is opened by the movable contact


22


, the movable contact comes into contact with a required region


94


of the fourth metal film


92


. The required region


94


of the fourth metal film


92


is composed of a copper layer as an undercoat, nickel layer as an intermediate layer and a gold layer as an outer layer. The remainder of the fourth metal film


92


other than the required region


94


is composed of a copper layer as the undercoat and a nickel layer as the outer layer.




The first spring member


42


is of a T-shaped spring having an attachment hole


43


at one end, as shown in FIG.


7


A. To fix the first spring member


42


to the subbase


30


, the spring holder


36


is inserted into the attachment hole


43


of the first spring member, as shown in FIG.


7


B. By use of this spring holder


36


integrally formed with the subbase


30


, it is possible to readily mount the first spring member


42


at a required position on the subbase with accuracy. Since the stopper


37


restricts the excessive motion of the first spring member


42


, it is possible to prevent the occurrence of abnormal contact pressure between the movable contact


22


and the fixed contacts


70


.




As shown in

FIGS. 8A

to


8


D, the contact member


21


is composed of a cylindrical body


23


having a dome-shaped top


24


and the movable contact


22


of a metal plate projecting from the side face of the cylindrical body in the opposite two directions. The second spring member


45


is of a rhombus shape having a first notch


46


for receiving the dome-shaped top and a second notch


47


for receiving the cylindrical body


23


of the contact member


21


. As shown in

FIG. 8A

, the contact member


21


and the second spring member


45


are assembled by inserting the contact member into the first and second notches


46


,


47


. The contact member


21


has incisions


26


in the dome-shaped top, to which the first notch


46


of the second spring member


45


is fitted, as shown in FIG.


8


C.




The assembly of the contact member


21


and the second spring member


45


is attached to the rectangular through-hole


32


of the subbase


30


such that the contact member receives the spring bias of the second spring member in the direction of spacing the movable contact


22


from the fixed contacts


70


when the contact sub block


2


is mounted on the contact base block


1


, as shown in FIG.


1


. When the first spring member


42


is pushed down by the armature


52


, the contact member


21


is moved against the spring bias of the second spring member


45


to close the fixed contacts


70


by the movable contact


22


. On the contrary, when the armature is released from the motion of the armature


52


, the contact member


21


is pushed upward by the spring bias of the second spring member


45


to leave the movable contact


22


from the fixed contacts


70


. At this time, as described above, the movable contact


22


comes into contact with the required region


94


of the fourth metal film


92


.




As shown in

FIG. 2

, the coil block


4


is an injection-molded article of an electrical insulating material, which houses the electromagnet


3


including a coil, iron core, and a permanent magnet and the armature


52


. When the coil block


4


is mounted on the contact sub block


2


, as shown in

FIGS. 9A and 9B

, pivot shafts


53


of the armature


52


are supported by the bearing portions


35


of the subbase


30


such that the armature can be driven in the seesaw fashion by energizing the electromagnet


3


.




The high frequency relay having the above-explained structure operates as follows. The electromagnet


3


is energized by applying a required voltage thereto, so that the armature


52


is driven in the seesaw fashion. For example, when the armature is driven, as shown in

FIG. 1

, the motion of the armature


52


is transferred to one of the contact members


21


through the first spring member


42


, so that the contact member is moved against the spring bias of the second spring member


45


to obtain a connection between the fixed contacts


70


(


b


),


70


(


c


) by the movable contact


22


(


b


). On the other hand, since the motion of the armature


52


is not transferred to the other one of the contact members


21


, the contact member receives the spring bias of the second spring member


45


, so that the movable contact


22


(


a


) is spaced from the fixed contacts


70


(


a


),


70


(


b


), and comes into contact with the fourth metal film


92


of the subbase


30


. From the above, the high frequency signals flow between the fixed contacts


70


(


b


),


70


(


c


) with the help of the movable contact


22


(


b


).




A modification of the contact base block of the above embodiment is shown in

FIGS. 10A

to


10


C, which is substantially the same as that of above embodiment except for the following structural features. That is, this contact base block


1


is characterized by comprising a shield wall


25


integrally formed with the base


10


to separate a first contact set of the fixed contacts (upper 3 fixed contacts


70


of

FIG. 10A

) and the contact members


21


used to switch a high frequency signal from a second contact set of the fixed contacts (lower 3 fixed contacts


70


of

FIG. 10A

) and the contact members


21


used to switch another high frequency signal. The formation of the shield wall


25


is effective to improve signal isolation performance between the first and second contact sets and prevent the occurrence of signal leakage. Alternatively, the shield wall


25


may be integrally formed with the subbase


30


, or completed by a first shield wall integrally formed with the base and a second shield wall integrally formed with the subbase.




In the above embodiment, the conductive layer


68


is formed on the inner surface of the respective through holes


16


and then the sealing material


62


is charged into the through holes. As shown in

FIGS. 11A and 11B

, a metal pin


65


may be inserted into the through hole


16


to make the electrical connection between one of the fixed contacts, i.e., the first metal films


70


, and the corresponding second metal film


80


. In this case, it is preferred to determine the length of the metal pin


65


such that a top end of the metal pin inserted into the through hole slightly projects on the first metal film


70


, as shown in FIG.


11


B. Since the movable contact


22


comes into contact with the top end of the metal pin


65


, it is possible to provide an extended life of the fixed contacts


70


. The metal pin


65


may be press-inserted into the through hole


16


or fixed to the through hole by use of an adhesive.




As the sealing material charged into the through hole


16


,


17


of the base


10


, for example, it is preferred to use an epoxy resin. In this case, since shrinkage of the epoxy resin is caused in the through hole by heating and drying the charged epoxy resin, it is possible to stably perform the sealing operation without allowing the resin to overflow from the through hole. In place of the charge of the sealing material, a synthetic-resin pin may be inserted into the through hole and then melted therein.




In place of the formation of the conductive layer in the through hole


16


and the charge of the sealing material


62


into the through hole, a conductive paste material such as silver, nickel and solder pastes may be charged into the through hole


16


. In this case, since electric current flows between the first and second metal films


70


,


80


through the charged conductive paste material having an increased cross section, it is possible to reduce the electrical resistance and provide an improved shield effect.




In case of charging the sealing material or the conductive paste material, it is preferred that the through hole is a countersunk hole


19


, as shown in

FIGS. 12A and 12B

. That is,

FIG. 12A

shows a state of the instant following of charging the sealing material


62


into the countersunk hole


19


, and

FIG. 12B

shows the sealing material


62


cured in the countersunk hole. Since a diameter of the through hole in the vicinity of the first metal film


70


is greater than the diameter of the interior of the through hole, it is possible to effectively prevent the overflow of the sealing material


62


or the paste material from the through hole.




Next, a contact base block and a contact sub block of the high frequency relay according to another embodiment of the present invention are explained referring to the attached drawings.





FIGS. 13A

to


13


D show a base


10


of the contact base block


1


that is an injection-molded article of an electrical insulating material. The base


10


is of a rectangular plate shape having rectangular projections


14


on its front surface. First, second and third metal films


70


,


80


,


90


are formed on the base


10


, as shown in

FIGS. 14A

to


14


D. That is, the first metal films


70


are formed on the projections


14


. Each of the second metal films


80


is formed at a position opposed to the corresponding one of the first metal films


70


on a rear surface of the base. The first metal film


70


is electrically connected to the corresponding second metal film


80


by a sixth metal film


72


formed on side surface of the base


10


, as shown in FIG.


14


B. The third metal film


90


is formed to extend from the front surface to the rear surface through the side surfaces of the base


10


. The first, second and sixth metal films


70


,


80


,


72


are isolated from the third metal film


90


by an isolation area


50


having no metal film. Each of the rectangular projections


14


has a pair of rounded sides on its top to prevent the occurrence of arc discharge between the fixed contacts


70


and the movable contact


22


, as shown in FIG.


15


. The numeral


100


designates coil electrodes for supplying electric power to the electromagnet


3


of the high frequency relay, which are electrically isolated from the third metal film


90


by the isolation area


50


.





FIGS. 16A

to


16


D show a subbase


30


of the contact sub block


2


that is an injection-molded article of an electrical insulating material. The subbase


30


is of a rectangular case shape composed of a bottom wall


31


, side walls


39


jutting from the periphery of the bottom wall, and a top opening. The side walls


39


have concaves


33


, to which the rectangular projections


14


of the base


10


are fitted when the contact sub block


2


is mounted on the contact base block


1


. Therefore, these projections


14


and the concaves


33


also function as guide means for readily and accurately mounting the contact sub block


2


on the contact base block


1


.




As shown in

FIGS. 17A

to


17


D, a fourth metal film


92


is formed on inner surfaces of the rectangular case of the subbase


30


. The third metal film


90


on the base


10


makes an electromagnetic shield space for preventing a leakage of high frequency signal in cooperation with the fourth metal film


92


when the contact sub block


2


is mounted on the contact base block


1


. The numeral


32


designates circular through-holes, to each of which the assembly of the contact member


21


having the movable contact


22


and the first spring member


45


is attached.




Next, an embodiment of a method of manufacturing the contact base block


1


of the high frequency relay of the present invention is explained referring to

FIGS. 18A

to


18


F.




After the base


10


is injection-molded with the electrical insulating resin material (FIG.


18


A), a chromium film


110


is deposited on the base


10


by spattering, as shown in FIG.


18


B. Next, a copper film


120


is deposited on the chromium film


110


by spattering in the atmosphere of argon, as shown in

FIG. 18C

, to obtain an undercoat. The chromium film


110


is effective to improve adhesion between the base


10


and the copper film


120


. Then, as shown in

FIG. 18D

, a part of the undercoat is removed from the base


10


by irradiating a laser beam


200


to the undercoat along a required pattern to obtain a patterned undercoat. Next, as shown in

FIG. 18E

, an intermediate layer


130


of nickel is formed the patterned undercoat by electroplating, and then an outer layer


140


of gold is formed on the intermediate layer


130


by electroplating, as shown in FIG.


18


F. According to the above method, the first, second and third metal films


70


,


80


,


90


can be formed at a time on the base


10


.




In case of controlling the plating thickness of the gold layer such that the thickness of the gold layer of the first metal film


70


is thicker than that of the third metal film


90


, for example, it is preferred to perform the electroplating by use of electrode members


210


shown in

FIGS. 19 and 20

. That is, the nickel layers of the first metal films


70


are connected to a power source


220


through electrode members


210


. On the other hand, the nickel film of the third metal film


90


is connected to the same power source


220


through a resistance R. The electrode members


210


are electrically isolated from the third metal film


90


. Since a smaller amount of electric current is supplied to the nickel film of the third metal film


90


due to the presence of the resistance R, it is possible to readily obtain the third metal film


90


having a reduced thickness of the gold layer.




In addition, it is possible to form the gold layers on only the nickel layers of the first metal films


70


by electroplating. That is, as shown in

FIG. 21

, the nickel layers of the first metal films


70


are connected to a first power source


220


through the electrode members


210


. On the other hand, the nickel layer of the third metal film


90


is connected to a second power source


230


. In case of the electroplating of gold, electric current is supplied to only the nickel films of the first metal films


70


from the first power source


220


. On the other hand, when the electroplating of a metal other than gold is required for the third metal film


90


, electric current is supplied to only the nickel film of the third metal film from the second power source


230


.




A further preferred embodiment of the method of manufacturing the contact base block of the high frequency relay of the present invention is explained referring to

FIGS. 22A

to


22


K.




After the base


10


is injection-molded with the electrical insulating resin material (FIG.


22


A), a roughing treatment


300


is performed on a surface of the base


10


with use of sodium hydroxide, as shown in FIG.


22


B. Next, a catalyst


310


is applied on the roughed surface


300


, as shown in FIG.


22


C. Then, an undercoat of copper


320


is formed on the roughed surface with the catalyst by electroless plating, as shown in FIG.


22


D. After a photoresist film


330


is formed on the undercoat


320


, as shown in

FIG. 22E

, a laser beam


340


is radiated to the photoresist film


330


along a required pattern, as shown in FIG.


22


F. By developing this, a patterned resist film is obtained on the undercoat.




The exposed undercoat is removed from the base


10


by chemical etching (FIG.


22


G). Since a required region of the undercoat


320


is removed by use of the patterned resist film


330


by the laser beam


340


, it is possible to readily obtain a precision pattern of the undercoat. At this time, since the catalyst remains on the exposed surface of the base


10


, it is preferred to remove the insulating material in the vicinity of the exposed surface of the base together with the remaining catalyst by use of sodium hydroxide, as shown in FIG.


22


H. Thus, a fresh surface


360


of the base


10


is exposed along the required pattern. Next, the patterned resist is removed to obtain a patterned undercoat


320


of copper, as shown in FIG.


221


. Then an intermediate layer


370


of nickel is formed on the patterned undercoat


320


by electroplating, and an outer layer


380


of gold is formed on the intermediate layer


370


, as shown in

FIGS. 22J and 22K

. If necessary, the step of

FIG. 22H

may be omitted.




From understood from the above embodiments, the present invention provides the high frequency relay with a refined structure having the capability of enhancing the assembly task of the relay and effectively preventing the leakage of high frequency signals.



Claims
  • 1. A high frequency relay comprising a contact base block having at least one pair of fixed contacts, at least one contact member with a movable contact, and an electromagnet for moving said contact member to open and close said pair of fixed contacts by said movable contact,wherein said contact base block comprises: a base having at least one pair of projections on its top surface, which is an injection-molded article of an electrical insulating material; first metal films formed as said fixed contacts on top surfaces of said projections; second metal films formed as connection terminals for outside devices on said base, each of which corresponds to one of said first metal films; connecting means for making an electrical connection between each of said first metal films and the corresponding second metal film; and a third metal film at least formed on the top surface of said base to provide electrical isolation from said first and second metal films, which works as electromagnetic shield means.
  • 2. The high frequency relay as set forth in claim 1, wherein said third metal film extends from the top surface to a bottom surface through side faces of said base, which works as ground means as well as said electromagnetic shield means.
  • 3. The high frequency relay as set forth in claim 2, wherein said base has at least one through hole extending from the top surface to the bottom surface of said base, in which an electrically conductive material is coated to make an electrical connection between parts of said third metal film on the top and bottom surfaces of said base in the shortest distance.
  • 4. The high frequency relay as set forth in claim 1, wherein each of said projections has a first projection jutting from the top surface of said base and a second projection jutting from said first projection, and wherein each of said first metal films is formed on a top of said second projection and said third metal film is formed on side faces of said first projections.
  • 5. The high frequency relay as set forth in claim 1, wherein each of said projections has a rounded top, on which said first metal film is formed.
  • 6. The high frequency relay as set forth in claim 1, each of said first, second and third metal films is composed of a copper layer as an undercoat, nickel layer as an intermediate layer, and a gold layer as an outer layer, and wherein a thickness of the outer layer of said first metal films is greater than that of said second and third metal films.
  • 7. The high frequency relay as set forth in claim 1, comprising fifth metal films formed as coil electrodes for supplying electric power to said electromagnet on said base so as to provide electrical isolation from said first, second and third metal films.
  • 8. The high frequency relay as set forth in claim 1, comprising a contact sub block for movably supporting said contact member, which comprises:a subbase that is an injection-molded article of an electrical insulating material; and a fourth metal film formed on a surface of said subbase in a face to face relation with the top surface of said base when said contact sub block is mounted on said contact base block, so that said pair of fixed contacts are opened and closed by said movable contact in an electromagnetic shield space surrounded by said third and fourth metal films.
  • 9. The high frequency relay as set forth in claim 8, wherein said movable contact comes into contact with a required region of said fourth metal film when said pair of fixed contacts are opened by said movable contact, and wherein the required region of said fourth metal film is composed of a copper layer as an undercoat, nickel layer as an intermediate layer and a gold layer as an outer layer, and the balance of said fourth metal film is composed of a copper layer as the undercoat and a nickel layer as the outer layer.
  • 10. The high frequency relay as set forth in claim 8, comprising a first contact set of a first pair of fixed contacts and a first contact member used to switch a high frequency signal and a second contact set of a second pair of fixed contacts and a second contact member used to switch another high frequency signal, and wherein a shield wall for isolating said first contact set from said second contact set is integrally-molded with at least one of said base and said subbase.
  • 11. The high frequency relay as set forth in claim 8, comprising a coil block for housing said electromagnet, and wherein said subbase has coil block supporting means for supporting said coil block, which is integrally molded with said subbase.
  • 12. The high frequency relay as set forth in claim 11, wherein said coil block comprises an armature disposed between said contact member and said electromagnet and driven by energizing said electromagnet, and wherein a motion of said armature is transferred to said contact member through a first spring member held by spring holding means integrally molded with said subbase.
  • 13. The high frequency relay as set forth in claim 12, said coil block supporting means and said spring holding means are provided to a surface opposed to the surface having said fourth metal film of said subbase, and said contact member is attached to a through hole formed in said subbase with a second spring member such that said contact member receives a spring bias of said second spring member in a direction of spacing said movable contact from said fixed contacts, and wherein said contact member can be moved against the spring bias of said second spring member by said first spring member pushed by said armature to close said fixed contacts by said movable contact.
  • 14. The high frequency relay as set forth in claim 1, wherein each of said second metal films is formed on a bottom surface of said base at a position opposed to the corresponding one of said first metal films.
  • 15. The high frequency relay as set forth in claim 14, wherein said connecting means is metal pins, each of which is inserted into said base to electrically connect one of said first metal films with the corresponding second metal film in the shortest distance.
  • 16. The high frequency relay as set forth in claim 14, wherein said connecting means is through holes each having a conductive layer on its inner surface, each of which is formed in said base to electrically connect one of said first metal films with the corresponding second metal film in the shortest distance.
  • 17. The high frequency relay as set forth in claim 14, wherein said connecting means is through holes, each of which is filled with an electrically conductive material and formed in said base to electrically connect one of said first metal films with the corresponding second metal film in the shortest distance.
  • 18. The high frequency relay as set forth in claim 14, wherein each of said second metal films extends from the bottom surface to a side surface of said base, and said second metal films on the side surface are used to electrically connect with the outside devices.
  • 19. A high frequency relay comprising a contact base block having at least one pair of fixed contacts, at least one contact member with a movable contact, a contact sub block for movably supporting said contact member, and an electromagnet for moving said contact member to open and close said pair of fixed contacts by said movable contact,wherein said contact base block comprises: a base that is an injection-molded article of an electrical insulating material; first metal films formed as said fixed contacts on a top surface of said base; second metal films formed as connection terminals for outside devices on said base, each of which corresponds to one of said first metal films; connecting means for making an electrical connection between each of said first metal films and the corresponding second metal film; and a third metal film at least formed on the top surface of said base to provide electrical isolation from said first and second metal films, which works as electromagnetic shield means, and wherein said contact sub block comprises: a subbase that is an injection-molded article of an electrical insulating material; and a fourth metal film formed on a surface of said subbase in a face to face relation with the top surface of said base when said contact sub block is mounted on said contact base block, so that said pair of fixed contacts are opened and closed by said movable contact in an electromagnetic shield space surrounded by said third and fourth metal films.
Priority Claims (1)
Number Date Country Kind
11-363617 Dec 1999 JP
US Referenced Citations (4)
Number Name Date Kind
5008487 Shimmyo Apr 1991 A
5673011 Okihara et al. Sep 1997 A
5994986 Takahashi Nov 1999 A
6288622 Okihara Sep 2001 B1
Foreign Referenced Citations (1)
Number Date Country
1-274333 Nov 1989 JP