WO1996030918A1

WO1996030918A1 - Contact unit, especially for electric switches

Info

Publication number: WO1996030918A1
Application number: PCT/DE1996/000607
Authority: WO
Inventors: Daniela Zuk; Willibald Lenhart
Original assignee: Eaton Controls Gmbh & Co. Kg
Priority date: 1995-03-31
Filing date: 1996-03-27
Publication date: 1996-10-03
Also published as: EP0818047A1; ES2136394T3; DE19511877A1; DE59602630D1; EP0818047B1

Abstract

A contact unit (1), especially for electric switches, comprises a stamped grid (2) of electrically conductive material in which the stamped tracks (4, 4a, 4b, 4c) representing the electric current paths are joined by webs (5) and have contacts (3) projecting from the stamped plane, in which the space between the stamped tracks (4, 4a, 4b, 4c) is smaller than the length of a contact (3). To obtain a compact contact unit (1), the contacts (3) are in one piece with the stamped grid (2) and the stamped grid (2) has at least one lug (15) in the longitudinal direction of the contacts (3) making it possible to bend the contacts (3) from the stamped plane of the grid (2) and space the contacts (3) in a predetermined grid pattern.

Description

Contact unit, especially for electrical switches

description

The invention relates to a contact unit, in particular for electrical switches, with a lead frame made of electrically conductive material, in which the lead tracks representing the electrical current paths are connected via webs and connecting contacts projecting from the die plane are provided, the space between the lead tracks being smaller is the length of a connector.

Such contact units for electrical switches are known. 1 to 3, a lead frame of such a contact unit is shown. So that the contact unit and thus the switch are given a compact structure, the punched tracks representing the current paths are closely arranged to one another. On the lead frame there are also the connection contacts which are connected to the current paths in the interior of the switch. In order to maintain the compact structure also for the area of the connection contacts and to be able to use commercially available compact connection plugs which accommodate a plurality of connection contacts, the connection contacts are always in a predetermined narrow grid with respect to one another. As can be seen from FIG. 1, the space between the Punching paths are not sufficient to connect the connecting contacts in one piece to the lead frame. To maintain the narrow grid spacing, two techniques are usually used. In the first type, a right and a left partial punched grid are produced with bent connection contacts present on the partial punched grids. The punching webs are connected to at least one contact plate overlapping the ends of the punching webs of the partial punching grid, whereby a one-part punched grid is produced. In the second type, a large, continuous lead frame is produced. The connection contacts are not yet present on this lead frame, since the distance between the punch webs is not sufficient for the one-piece formation of the connection contacts on the lead frame. In a separate operation, the connecting plugs are produced with a contact surface for attachment to the lead frame. The connector is usually connected to the lead frame by welding or riveting. Every connection point has to meet high quality requirements. On the one hand, an adequate electrical connection must be ensured, which in turn requires a high level of cleanliness of the parts before connection. On the other hand, the connection must also have a mechanically sufficient holding force.

For the lead frames of the contact units according to the prior art, several individual parts are required, which have to be assembled in various work steps. Thus, in the embodiment according to FIG. 2 five individual parts are required, which are joined together with a total of six connection points become. In the embodiment according to FIG. 3, even eight individual parts are required, which are joined together with seven connection points.

The invention has for its object to provide a contact unit of the type mentioned, which has a compact structure with a one-piece design, is inexpensive to manufacture and meets the highest quality requirements.

This object is achieved in that the connection contacts are formed in one piece with the lead frame, and the lead frame has at least one loop lying in the longitudinal direction of the connection contacts, which bends the connection contacts out of the punching plane of the lead frame and spacing the connection contacts allows a given grid dimension.

By means of these measures, the leadframe with the connection contacts can be produced as a one-piece part in a cost-effective manner while maintaining a predetermined, narrow grid dimension while at the same time meeting the highest quality requirements. No additional work steps are required.

According to an advantageous embodiment of the invention, the elongated length of the loop corresponds to the length of the connecting contacts bent out of the lead frame and the width of a free punching between the free end of the connecting contacts and opposite regions of the lead frame. ters in the longitudinal direction of the loop taking into account the bending correction factor. By making the loop of different lengths, different contact units can be produced from a lead frame, which take into account different grid dimensions and connection contact lengths.

According to an advantageous development of the invention, embedded in the bending direction of the loop are connection contacts lying opposite, which can be bent out of the lead frame at right angles and can be brought to the desired grid size by bending the loop. In this way, the connection contacts can be arranged directly opposite one another, i.e. the connection contacts do not have to be offset from one another.

In an advantageous embodiment, at least two punched tracks spaced apart in the lead frame and running parallel to one another each have a loop. This gives the lead frame a stiff and firm structure, which enables easier handling during assembly. Installation errors are avoided by introducing the loop differently, offset or opposite.

So that the loops can be introduced into the punched tracks at different points without this leading to the lead frame being distorted, preference is given between the punched tracks each having the loop and the connecting contacts which are made available by bending out Punching tracks no webs connecting the punching tracks are present.

According to a further embodiment of the invention, at least one contact strip runs transversely to the alignment of the connection contacts and serves as a contact point on the punched tracks after the punching. This configuration meets increased demands on the electrical load-bearing capacity, whereby no additional operations are required for producing the higher-strength and electrically qualitatively better stamped grid, such as, for example, by riveting on contact rivets would be necessary.

The contact strips lie as an inlay or as a toplay on the punched strip in one direction. Since different electrical requirements occur in the switch or on a connection contact, it is necessary to meet these requirements by the presence of a specific contact material. However, in order not to have to apply too many contact strips, which also incur costs, the contact point is expediently brought to the desired position by at least one loop in the punched track of the connecting contact.

So that the connection contacts have the same length after the positioning of the contact points, the connection contacts embedded in the lead frame are expediently of different lengths. After positioning, the are Connection contacts of the same length and the bend can be made via a bending edge.

When producing the lead frame, it is not always possible to make the connection contacts of the same length. For example, in terms of tool technology, it is necessary to make thin cutting dies coherent for reinforcement, which leads to an offset of the cutting edges. The connection contacts of different lengths are therefore preferably given the same length by a loop.

On the one hand, contact points must be brought to the correct place for the electrical requirement and, on the other hand, the connection contacts must be brought to the required grid dimension. According to a further embodiment, this is achieved in that a punched track has at least two loops, through which at least one contact point and / or a connection contact is positioned.

In a further advantageous embodiment, the loops in the lead frame are present on the side opposite the connection contacts. This results in the loops being accommodated in the interior of the switch, as a result of which no additional measures are necessary to protect the loops from damage or contact.

The lead frame representing the contact unit still has to be separated into the individual current paths, the lead frames realizing the current paths being electrically separate from one another must be fixed in isolation. The handling of the contact unit should take place as part for cost reasons. Therefore, according to a development of the invention, the lead frame is fastened on an insulating plastic part, the webs of the lead frame being separated between the punched tracks after the lead frame has been fastened.

According to an advantageous embodiment, the lead frame is attached to the plastic part by extrusion coating with plastic, the contact surfaces of the lead frame and the connecting contacts not being extrusion-coated, and the encapsulation being carried out in a tool producing the plastic part. By means of these measures, the lead frame is held in an electrically insulated manner, and when the extrusion coating is carried out, the switch part, which is required anyway, is simultaneously produced, for example a base.

In the following description, the prior art and then the invention are explained in more detail using the exemplary embodiments shown in the drawing. Show it:

1 is a plan view of a lead frame of a known contact unit,

2 is a side view of the lead frame and FIG. 1 in the direction of arrow II, 3 shows an alternative embodiment of the representation according to FIG. 2,

4 shows a plan view of a lead frame for producing a lead frame of a contact unit according to the invention,

5 shows a side view of a contact unit made from the lead frame in the direction of arrow V according to FIG. 4,

6 is a view of the contact unit of FIG. 5 in the direction of arrow VI,

7 is a plan view of an overmolded contact unit according to the invention,

Fig. 8 is a side view of the contact unit according to

7 in the direction of arrow VIII with a partial section in the region of the loop,

9 is a plan view of a lead frame with contact strips for the production of a according to the invention,

10 is a plan view of the lead frame according to FIG. 9 after introducing small loops,

11 is a side view of the lead frame according to Figure 10 in the direction of arrow XI, Fig. 12 is a plan view of the contact unit made of the lead frame shown in FIG. 10 and

13 is a side view in the direction of arrow XIII according to FIG. 12.

1 to 3, which represent the state of the art, show a contact unit 1 which, in its large extent, consists of a substantially rectangular lead frame 2. On the contact unit 1, the connection contacts 3 protrude from the plane of the lead frame 2. In the plane of the lead frame 2, the punched webs 4 represent the current paths. The webs 4 are connected by webs 5 between the punched webs 4 and thus form the lead frame 2. In the plane of the lead frame 2, diagonally opposite holding bores 12 are inserted, with which the lead frame 2 is positioned. Furthermore, large openings 13 are provided in the lead frame 2, which are used for other functions within an electrical switch. The contact unit 1 according to FIG. 1 has a total of seven connection contacts 3. In each case three connection contacts 3 are arranged opposite one another. All seven connection contacts 3 are in a grid to each other. The clearance 14 in the plane of the lead frame 2 between the connection contacts 3 is by no means wide enough to be able to accommodate the length of the bent connection contacts 3. The contact unit 1 according to FIG. 2 consists of a right lead frame 6 and a left leadframe 7 on which the connecting contacts 3 are present and bent in one piece. The right lead frame 6 is connected to the left lead frame 7 via the punched tracks 4a, 4b and 4c on the longitudinal sides 8. With the help of the width of the punch webs 4a, 4b and 4c corresponding contact plates 9, which are welded onto the top 10 of the punched grid 6, 7, the punched grid 6, 7 are connected to the contact unit 1. An alternative to this is shown in FIG. 3. Here, the contact unit 1 consists of a flat continuous lead frame 2, on the underside 11 of which angled connection contacts 3 are welded.

A lead frame 2 for a contact unit 1 according to the invention is shown in FIG. The lead frame 2 also has the openings 13 and holding bores 12. In the plane of the lead frame 2, the connection contacts 3 are still folded, which are integrally connected to the lead frame 2. Between the free end of the connection contacts 3 there is still sufficient space for the punching 14. The outer areas of the lead frame 2, in which the holding bore 12 and the openings 13 are provided, are identical to the lead frame 2 according to the prior art. Only the punched webs 4a, 4b and 4c provided on the long sides 8 are longer, which means that the punched grid 2 has a greater length.

FIGS. 5 and 6 show the corresponding side views of the constructions produced from the lead frame 2 according to FIG. clock unit 1. The connecting contacts 3 are bent out of the plane of the lead frame 2 by 90 ° on the underside 11. So that the connection contacts 3 can be brought to the required grid dimension, the punched strips 4a, 4b and 4c arranged on the longitudinal sides 8 each have a U-shaped loop 15. The bending direction of the loop 15 lies in the longitudinal direction of the connection contacts 3, and the loop 15, or the punched strips 4a, 4b and 4c, are carried out so long that a spacing of the connection contacts 3 to the predetermined grid size is made possible. The legs 16 of the loop 15 run at an acute angle to one another, whereby a bending punch forming the loop 15 can be easily immersed and pulled out.

So that the existing on the contact unit 1 Kontaktkontak¬ te 3 can be brought to the required pitch, the length of the loop 15 is equal to the length of the bent out of the lead frame 2 contacts 3 plus the width of the punch 14, which is between the free end of the contact 3 and the opposite part of the lead frame 2 is present. In this case, only the width of the relief 14 in the longitudinal direction or the bending direction of the loop 15 is taken into account. The bending correction factor is also taken into account when calculating the stretched length of the loop 15.

As can be seen from FIG. 4, the connecting contacts 3 lie opposite each other in the bending direction of the loop 15 in the lead frame 2, and the bending edge 17 of the connecting contacts 3 runs perpendicular to the longitudinal sides 8 of the lead frame 2. When calculating the elongated length of the loop 15, the part opposite the free end of the connecting contacts 3 is always taken into account. In the embodiment according to FIG. 4, two free ends of connection contacts 3 lie opposite one another. The clearance 14 is thus the area between the free ends of the contacts 3.

5 and 6 that the loops 15 are bent towards the top 10 of the contact unit 1. In FIG. 5, only the loop 15 present in the punching path 4c can be seen. The loops 15 present in the punching tracks 4a and 4b lie congruently behind them. Thus, a loop 15 is bent into all punched tracks 4a, 4b and 4c, which represent the connection for the parts of the punched grid 2 carrying the connecting contacts 3.

So that the connecting contacts 3 can be bent out of the plane of the lead frame 2 and the loops 15 can be formed, there are no connecting webs 5 between these punching webs. In this area, webs 5 would result in the webs 5 being bent after bending of the connecting contacts 3 and after the loops 15 had been bent in would be very difficult to separate, since these would no longer be present in one plane. If, on the other hand, the loops 15 are to be bent in at different points between the punch webs 4a and 4b, there would be a delay between the punch webs 4a and 4b in addition to the difficulties mentioned first. 9 to 13, contact units 1 and lead frames 2 are shown, each carrying two contact strips 18 transversely to the alignment of the connecting contacts 3. The contact strip 18 is introduced in the manner of an inlay, as can be seen from FIGS. 11 and 13. However, a toplay material can also be used in which the contact material is applied to the top 10 of the lead frame 2. Both rolled strips and an electroplated thin strip layer can be used. After the punching, only contact points 19 remain on the punched tracks 4 of the punched grid 2 or the contact unit 1 of the contact strips 18 (see FIGS. 9, 10 and 12).

As can further be seen from FIG. 9, the connection contacts 3 embedded in the lead frame 2 have a different length. However, the contact points 19 are still in the area of the previously existing contact strip 18. Since different electrical requirements are present on the top 10 of the contact unit 1, these requirements should be taken into account with a contact point 19. In order to avoid that too many contact strips 18 are required, the contact point 19 in the lead frame 2 or the contact unit 1 is displaced by introducing a loop 15. This is clearly evident from FIG. 10, in which the contact points 19 have been moved out of the area of the contact loops 18 by introducing three loops 15. Thus, on the one hand, the fact that different contact points 19 are required on the top side 10 is taken into account, and on the other hand that 3 different contact points 19 are necessary on the connection contacts. So that the connection contacts 3 have the same length despite everything, the loops 15 in the connection contact feet 20 are designed such that these requirements are met.

In the contact unit 1 shown in FIG. 12, three loops 15 are incorporated in the punched tracks 4a and 4b. The loops 15 are located at different lengths of the respective punched web 4a or 4b and have a different depth, but the legs 16 of the loops 15 run at an acute angle to one another. This makes it possible for all the contact points 19 on the punched tracks 4 to have a position spaced apart from the original contact strip 18.

11 and 13 represent side views of contact units 1. In FIG. 11, the loops 15, which are rectangular in shape, are only bent in the direction of the underside 11 of the contact unit 1. This state represents an intermediate state in which the connection contacts 3 have not yet been bent out of the plane of the lead frame 2. In the subsequent operation, the connection contacts 3 are then bent out and the further loops 15 are added. A contact unit 1 similar to that in FIG. 11 is shown in FIG. 13, which has already gone through this working step and thus carries the loops 15 on the upper side 10. 7 and 8, the contact unit 1 is already attached to a plastic part 21. The plastic part 21 is the base of a switch which is held in a housing, not shown, via clip lugs 22. The contact unit 1 is fastened in the electrically insulating plastic part 21 by injection molding with plastic in a tool, the contact unit 1 being adjusted in its holding bores 12. The base receives its usage form directly. The contact surfaces 23 and the connecting contacts 3 of the contact unit 1 are not overmolded. The connecting contacts 3 protrude from the underside 24 of the plastic part 21 and are surrounded by a plug collar 25 in a protective manner. The loops 15 which are bent on the long sides 8 of the contact unit 1 in the direction of the upper side 10 are also extrusion-coated and thus protected.

The punched webs 4 are separated into their individual current paths after being fastened. For this purpose, the webs 5 are punched out at separating points 27. By differently punching out the webs 5, different current paths can now also be realized.

In the area of the openings 13 in the lead frame 1, latching links 26 are formed in the plastic part 21, which interact with latching elements, not shown, held in the switch.

Claims

claims

1. Contact unit, in particular for electrical switches, with a lead frame made of electrically conductive material, in which the lead paths representing the electrical current paths are connected via webs and connecting contacts projecting from the lead plane are provided, the space between the lead paths being smaller is characterized as the length of the connection contacts, characterized in that the connection contacts (3) are formed in one piece with the lead frame (2) and the lead frame (2) has at least one loop () in the longitudinal direction of the connection contacts (3). 15), which allows the connection contacts (3) to bend out of the punching plane of the lead frame (2) and allows the connection contacts (3) to be spaced apart to a predetermined grid dimension.

2. Contact unit according to claim 1, characterized in that the extended length of the loop (15), the length of the leadframe bent out of the lead frame (2) (3) and the width of a cut-out (14) between the free end of the connection contacts ( 3) and opposite areas of the lead frame (2) in the longitudinal direction of the loop (15), taking into account the bending correction factor.

3. Contact unit according to one of claims 1 or 2, da¬ characterized in that in the lead frame (2) in the bending direction of the loop (15) connection contacts (3) are embedded opposite one another, which can be brought out at right angles from the lead frame (2) and can be brought to the desired grid size by bending the loop (15).

4. Contact unit according to claim 1 or 3, characterized gekenn¬ characterized in that at least two spaced in the lead frame (2) spaced, parallel to each other punched tracks (4a, 4b, 4c) each have a loop (15).

5. Contact unit according to one of claims 1 to 4, da¬ characterized in that between the respective loop (15) having punched tracks (4a, 4b, 4c) and by bending out the connecting contacts (3) provide punched tracks (4) there are no webs (5) connecting the punching webs (4, 4a, 4b, 4c).

6. Contact unit according to one of claims 1 to 5, da¬ characterized in that transversely to the orientation of the An¬ connection contacts (3) at least one contact strip (18) which on the punched tracks (4, 4a, 4b, 4c) after Stamping serves as a contact point (19).

7. Contact unit according to claim 6, characterized. that by at least one loop (15) in the punching path (4) of the connection contact (3) the contact point (19) is brought to the desired position.

8. Contact unit according to one of claims 6 or 7, da¬ characterized in that the embedded in the lead frame (2) embedded connecting contacts (3) have a different length.

9. Contact unit according to one of claims 6 to 8, da¬ characterized in that the connecting contacts (3) of different lengths are given the same length by a loop (15).

10. Contact unit according to one of claims 1 to 9, da¬ characterized in that a punched track (4, 4a, 4b, 4c) has at least two loops (15) through the at least one contact point (19) and / or a contact Kontakt¬ (3) is positioned.

11. Contact unit according to one of claims 1 to 10, da¬ characterized in that the loops (15) in the punched grid (2) on the opposite side of the connecting contacts (3) are present.

12. Contact unit according to one of claims 1 to 11, da¬ characterized in that the lead frame (2) is attached to an insulating plastic part (21), wherein after the attachment of the lead frame (2), the webs (5) of the lead frame (2) between the punching tracks (4, 4a, 4b, 4c).

13. Contact unit according to one of claims 1 to 12, da¬ characterized in that the fastening of the Stanzgit¬ ters (2) on the plastic part (21) by injection molding with plastic, the contact surfaces (23) of the lead frame (2) and the connection contacts (3) are not overmolded, and the overmolding is carried out in a tool producing the plastic part (21).