WO2000007199A2

WO2000007199A2 - Electromagnetic relay and method for producing the same

Info

Publication number: WO2000007199A2
Application number: PCT/DE1999/002338
Authority: WO
Inventors: Michael Dittmann; Jens Heinrich; Rainer Vogel; Titus Ziegler
Original assignee: Siemens Electromechanical Components Gmbh & Co. Kg
Priority date: 1998-07-30
Filing date: 1999-07-29
Publication date: 2000-02-10
Also published as: WO2000007199A3

Abstract

The invention relates to an electromagnetic relay, comprising a coil (1), a core (2), an armature (4), mobile contacts (5) which are located on the armature, a frame element (10) and fixed contacts (12) which are located on the frame element (10). The fixed contacts (12) are arranged on contact springs (9) which are fixed on the frame element (10) at their fixed ends and each have a free end. The invention also relates to a method for producing the inventive relay.

Description

description

Electromagnetic relay and process for its manufacture

The invention relates to an electromagnetic relay with a magnet system comprising a coil, a core, an armature and movable contacts arranged on the armature and with a contact system comprising a base element having fixed contacts and connection elements arranged on the base element for the fixed contacts and the sink.

In relays known from DE 197 19 355 Cl, the fixed contacts are usually welded onto stamped tapes and tapes overmolded with thermoplastic plastic. The connection elements are formed from these punched strips by bending, sealed with potting compound, cut to length and angled as an SMD connection.

The conventional relays have the disadvantage that punching metal strips causes high tool costs. The subsequent bending operation results in a large spread in the position of the fixed contacts with respect to the movable contacts, which results in a high probability of failure and consequently also leads to a high scrap in production. The thermoplastic used for the encapsulation has insufficient thermal stability against the temperatures that occur during reflow soldering. The curved and cut to length SMD connection pins have a wide spread with regard to the coplanarity and the fidelity ^" , which results in a high rejection during manufacture, soldering errors during soldering and a reduction in the lifespan of the soldering point geometric design of the contact systems, a change of the design is only possible with increased effort. The aim of the present invention is therefore to provide a relay that can be implemented without complex punching and bending operations that are critical with regard to the geometric dimensions.

This goal is achieved according to the invention by a relay according to claim 1. Advantageous embodiments of the invention can be found in the further claims.

The invention consists in an electromagnetic relay with a magnet system comprising a coil, a core, an armature and movable contacts arranged on the armature and with a contact system comprising a base element having fixed contacts and connection elements for the fixed contacts arranged on the base element and the coil, the fixed contacts being arranged on contact springs which are fixed to the base element with a fixed end and which have a free end.

Due to the arrangement according to the invention of the fixed contacts on contact springs, which are attached to the base element with a fixed end, the function of the relay no longer depends on the position in which the fixed contacts are located, since distance tolerances to the armature are compensated for by the spring action become.

In one embodiment, a fixed, plated-through circuit board with conductor tracks is used as the base element, the fixed ends of the contact springs being connected to the conductor tracks. This embodiment has the advantage that when the relay base is soldered onto a further printed circuit board, no thermal mismatch can occur between the base element and the printed circuit board. The conductor tracks forming the supply line to the fixed contacts can also be designed in a particularly simple and flexible manner on a printed circuit board. An insulating layer is preferably arranged between the movable contacts and the armature. With the movable contacts insulated from one another as a result, they can be designed particularly easily as bridge contacts, the movable contacts forming contact bridges which each cover two fixed contacts. The advantage of the bridge contacts is, on the one hand, that the power supply to the movable contacts can be dispensed with. On the other hand, the air gap between the fixed contacts and the movable contacts when the contacts are open becomes twice as effective as an electrical series connection of resistors, which increases the dielectric strength of the contacts against overvoltages. When applying high-frequency signals to the fixed contacts, this also results in higher crosstalk attenuation than with only one air gap.

In another embodiment of the relay according to the invention, the base element has additional connection elements for the movable contacts, which are connected to conductor tracks arranged on the insulating layer. The conductor tracks on the insulating layer are contacted with the corresponding connection elements by means of spring elements or via a flexible printed circuit board. This embodiment halves the number of required contact springs per contact compared to the bridge contacts, which can be used to increase the number of contacts with the same volume of the relay. The spring elements used for contacting the conductor tracks on the insulating layer are preferably arranged on arms of the insulating layer which project transversely outward in the region of the armature rotation axis. The arms also act as a torsion spring and act as an anchor spring.

If the relay structure according to the invention is used to manufacture high-frequency relays, it is particularly advantageous to have a conductor track on the relay base as a microstrip line to train. The microstrip line allows the wave resistance to be adapted particularly easily in the case of high-frequency signals, so that the electrical shielding required by the conventional high-frequency relays by means of a coaxial line can be dispensed with. The main disadvantage of these known coaxial lines is that they take up a lot of space.

The contact springs of the relay according to the invention can preferably be formed by electrodeposition of a layer of metal or a metal alloy and subsequent partial undercutting of the layer. The contact springs bulge upwards due to internal stresses in the deposited material with their free, under-etched ends in the direction of the armature. The spring characteristics can be set to a desired level by simply varying the deposited material or the deposited layer thickness.

Another possibility of producing the contact springs is their formation from strip material, which is bent by plastic deformation. The tape material can also be attached to the relay base with spacer elements without plastically deforming the spring. Undeformed contact springs can also be arranged with their free end over a pit arranged in the relay base. The advantage here is that it is possible to dispense with deforming the contact spring.

An embodiment is particularly advantageous in which the connection elements for the fixed contacts, the coil and possibly the movable contacts are formed as solder balls in connection with the plated-through holes of the printed circuit board, which are arranged on the side of the relay base facing away from the armature. These solder balls can be manufactured very simply with a fixedly defined diameter, and in connection with the flat circuit board there is almost no scatter in the coplanarity of the relay connections. The circuit board forming the base element is preferably made of thermosetting plastic. This has the advantage that it is stable against the temperatures that occur during reflow soldering.

It is particularly advantageous to design the fixed contacts as double contacts. These double contacts guarantee a safe contact even if the armature axis of rotation is slightly tilted and if there are any particles in a contact. The double contacts can be realized particularly easily by means of contact springs which are slotted in the longitudinal direction at their free ends.

In addition, the use of a plated-through circuit board as a base element for the relay enables the arrangement of further contact and magnet systems on this circuit board. As a result, several relays in a customer-specific matrix form can be accommodated in a common housing to save space.

Particularly advantageously, the circuit board forming the base element of the relay is additionally used as a wiring support for components which are usually used in external circuitry, such as electronic fuses, diodes, capacitors, resistors or drivers. In addition to such additional electrical components, connectors can also be arranged on the circuit board.

The invention is explained in more detail below with the aid of exemplary embodiments and the associated figures.

Figure 1 shows a relay according to the invention in a schematic longitudinal section. Figure 2 shows a first embodiment of the armature with the insulating layer in a schematic plan view of the contact side.

Figure 3 shows a first embodiment of the relay base with contact springs arranged thereon in a schematic plan view.

Figure 4 shows a second embodiment of the anchor with the insulating layer in a schematic plan view of the

Contact page.

FIG. 5 shows a second embodiment of the relay base with contact springs arranged thereon in a schematic plan view.

Figure 6 shows an embodiment of the armature with the insulating layer for use in RF relays in a schematic plan view of the contact side.

Figure 7 shows a first embodiment of the relay base with contact springs arranged thereon for use in RF relays in a schematic plan view.

Figure 8 shows a second embodiment of the relay base with contact springs arranged thereon for use in RF relays in a schematic plan view.

FIG. 9 shows an arrangement of several relays on a printed circuit board with components additionally arranged on the printed circuit board in a schematic longitudinal section.

Figure 10 shows the relay base with an electrodeposited contact spring before undercutting in a schematic longitudinal section 1 shows an electromagnetic relay with coil 1, coil body 23, core 2, first pole piece 2a, second pole piece 2b, a three-pole permanent magnet 3, and an armature 4. The armature 4 is fastened to the three-pole permanent magnet 3 with the aid of a bearing spring 17 . The intermediate piece 16 guarantees a minimum distance of the armature 4 from the three-pole permanent magnet 3 and at the same time bridges the air gap between the two. On the underside of the armature 4 there is an insulating layer 6, on which the movable contacts 5 are arranged. The entire magnet system is surrounded by a relay jacket 13 with a collar 14. With the collar 14, the relay sheath 13 is fastened on the plated-through circuit board 10. The plated-through circuit board 10 forms the base element of the relay and carries the connection elements 15 of the relay for the underside

Coil 1 and the fixed contacts 12. The connecting elements are designed as solder balls 15. The fixed contacts 12 are arranged on contact springs 9 on the inside of the printed circuit board 10. The plated-through holes 15 a shown in FIG. 1 contact the fixed contacts 12 with the corresponding solder balls 15.

FIG. 2 shows the insulating layer 6 with the armature 4 underneath and with the movable contacts 5, as can be designed for the execution of bridge contacts. The corresponding design of the plated-through circuit board 10 is shown in FIG. 3. Two fixed contacts 12 are provided on the printed circuit board 10 for each movable contact 5. The fixed contacts are arranged on contact springs 9. These contact springs 9 have a free end on which the fixed contacts 12 are arranged and a fixed end with which they are fastened on conductor tracks 9a running on the printed circuit board 10. The conductor tracks 9a are connected to the solder balls in an electrically conductive manner via plated-through holes 15a (FIG. 1). The contact springs 9 are slotted at their free ends in order to ensure reliable contacting. FIG. 4 shows a further embodiment of an elastic insulating layer 6 with an anchor 4 underneath. The movable contacts 5 are connected to conductor tracks 7 arranged on the insulating layer 6. The conductor tracks 7 are contacted with spring elements 8, which produce the electrical connection to the associated connection elements. The spring elements 8 are arranged in the region of the armature axis of rotation on arms 11 of the insulating layer 6 which project transversely outwards. These arms 11 in turn are supported on supports 11a fastened on the base element, so that a rocking movement of the armature about an axis running longitudinally to the spring elements 8 is possible.

The embodiment of the plated-through circuit board belonging to FIG. 4 is shown in FIG. FIG. 5 shows a printed circuit board 10 with conductor tracks 9a and supports 11a arranged thereon. The contact springs 9 with the fixed contacts 12 are arranged on the conductor tracks 9a. The fixed contacts 12 are connected via the contact springs 9 and

Conductor tracks 9a with the corresponding connection elements. Since in the insulating layer according to Figure 4, the movable contacts

5 are contacted with connection elements, only one fixed contact 12 on the printed circuit board 10 is required for each movable contact 5.

Figure 6 shows a further embodiment of the insulating layer

6 with fixed contacts 5 as contact bridges for use in an RF relay according to FIGS. 7 and 8.

FIG. 6 includes the embodiments of the plated-through circuit board 10 shown in FIG. 7 and in FIG. 8. FIG. 7 shows a circuit board 10 as a base element with fixed contacts 12 arranged thereon. The fixed contacts 12 are arranged on contact springs 9. The high-frequency signal lines to the fixed contacts 12 are realized by conductor tracks 18 arranged on the printed circuit board 10. The one to lead Ground line necessary for high-frequency signals is designed as a microstrip line 19, which is separated from the conductor tracks 18 by an insulating layer. This creates a ground line with an adapted characteristic impedance. The microstrip line 19 can be arranged on the side of the printed circuit board facing away from the fixed contacts 12 or in an intermediate plane of the printed circuit board. Coil contact elements 20 for connecting the coil are also arranged on the printed circuit board 10.

Figure 8 shows a plated-through circuit board 10 for use in an RF relay. Fixed contacts 12 are arranged on the printed circuit board 10. The fixed contacts 12 are arranged on contact springs 9. The high-frequency signals are supplied to the fixed contacts via conductor tracks 18a arranged on the printed circuit board. The ground line 18 necessary for the routing of RF signals is located on the same level as the signal lines and forms a coplanar waveguide with them. Coil contact elements 20 are also arranged on the printed circuit board 10.

FIG. 9 shows a multi-relay arrangement with additional components 21 arranged on the printed circuit board 10 and a plug connector 22 arranged on the printed circuit board 10. Contact systems with contact springs 9 belonging to several relays are arranged on the printed circuit board 10. The magnetic systems of the relays with their relay casings 13 are mounted on the printed circuit board 10 via these contact systems.

FIG. 10 shows the printed circuit board 10 with the copper layer 24 electrodeposited thereon. This copper layer 24 has a thickness of 35 μm, for example. The layer forming the contact spring 9 is electrodeposited on the copper layer 24. This layer consists, for example, of a nickel / iron alloy with a thickness of 50 μm. To improve the

Conductivity is a precious metal coating 25 on the contact spring 9, for example by sputtering or by means of electroplating, upset. This noble metal coating 25 typically has a thickness of 1 to 2 μm and consists, for example, of gold or silver. The solid contact 12 is finally deposited on the noble metal coating 25. In order to achieve the lowest possible line resistance, the fixed contact 12 is preferably made of gold. The nickel / iron layer 9 can be applied with high mechanical tension, so that a contact spring 9 bent away from the printed circuit board 10 can be produced by partially etching away the copper layer 24. By simultaneously depositing the layer stack shown on a printed circuit board 10, in conjunction with an etching process which runs in parallel, for example to be carried out by wet chemistry, the simultaneous production of many contact spring groups for several relays is possible.

The invention is not limited to the embodiments shown, but is defined in its most general form by claim 1.

Claims

claims

1. Electromagnetic relay with a magnet system, comprising - a coil (1), a core (2), an armature (4) and on the armature (4) arranged movable contacts (5) and with a contact system comprising a fixed contacts ( 12) having a base element (10) and on the base element (10) arranged connection elements for the fixed contacts (12), the fixed contacts (12) being arranged on contact springs (9) which have a fixed end on the base element (10) are attached and which have a free end.

2. Relay according to claim 1, wherein an insulating layer (6) is arranged between the movable contacts (5) and the armature (4).

3. Relay according to claim 2, wherein the movable contacts (5) form contact bridges, each covering two fixed contacts (12).

4. Relay according to claim 1, wherein the base element (10) has additional connection elements (12) for the movable contacts (5), which are connected to conductor tracks (7) arranged on the insulating layer (6), and wherein the conductor tracks (7) are connected to the additional connection elements via spring elements (8) or a flexible printed circuit board.

Relay according to claim 4, wherein the spring elements (8) in the region of the armature rotation Axially transversely outwardly projecting arms (11) of the insulating layer (6) are arranged.

6. Relay according to one of claims 1 to 5, wherein the base element is a fixed, plated-through circuit board (10) with conductor tracks (18) and wherein the fixed ends of the contact springs (9) are connected to the conductor tracks (18).

7. Relay according to claim 6, wherein one or more conductor tracks (18) are designed as microstrip lines (19) or as coplanar waveguides.

8. Relay according to one of claims 1 to 7, wherein the contact springs (9) are formed by electrodeposition of a layer of metal or a metal alloy and subsequent partial undercutting of the layer, and wherein the contact springs (9) are caused by internal stresses in the deposited material are arched with their free, under-etched end towards the anchor (4).

9. Relay according to one of claims 1 to 7, wherein the contact springs (9) are formed from strip material.

10. Relay according to claim 9, wherein the contact springs (9) are curved by plastic deformation.

11. Relay according to claim 9, wherein the contact springs (9) are fastened with spacer elements on the printed circuit board (10).

12. Relay according to claim 9, wherein the contact springs (9) with their free end over each project a pit arranged in the base element (10).

13. Relay according to one of claims 6 to 12, wherein the connection elements for the fixed contacts (12), the coil (1) and possibly the movable contacts (5) are formed from solder balls (15) which on the armature ( 4) facing away from the plated-through circuit board (10).

14. Relay according to one of claims 6 to 13, wherein the plated-through circuit board (10) consists of thermosetting plastic.

15. Relay according to one of claims 1 to 14, wherein the fixed contacts (12) are designed as double contacts.

16. Relay according to claim 15, wherein the contact springs (9) are slotted at their free ends in the longitudinal direction.

17. Relay according to one of claims 6 to 16, wherein further relays associated contact and magnet systems are arranged on the plated-through circuit board (10).

18. Relay according to one of claims 6 to 17, wherein additional electrical components (21) and / or plug connectors (22) are arranged on the plated-through circuit board (10).

19. A method for producing a relay according to claims 1 to 18, comprising the following steps: a) depositing an electrically conductive intermediate layer (24) on the base element (10) b) depositing an electrically conductive layer, which forms the contact springs (9) and is under tension, on the intermediate layer c) depositing the fixed contacts (12) on the contact springs (9) d) structuring the contact springs (9) e) partially undercutting the contact springs ( 9)

20. A method for producing a relay according to claim 17 or 18 corresponding to the method according to claim 19, wherein a plurality of contact springs (9) belonging to different relays are under-etched simultaneously in a wet or dry chemical etching process.