DE10349584A1 - Electrically conducting connection used in the production of a circuit board comprises forming a contact surface on a pin and/or bushing through a soft electrically conducting metallic external layer applied on a diffusion barrier layer - Google Patents

Abstract

Electrically conducting connection between a pressing pin (8) and a bushing (6) comprises forming a contact surface between the pin and bushing by plastic deformation. The contact surface is formed on the pin and/or bushing through a soft electrically conducting metallic external layer (13) applied on a diffusion barrier layer (11). The external layer has a thickness of 0.1-0.8 micronsm, preferably up to 6 micronsm.

Description

The present invention relates to an electrically conductive connection between a press-in pin and a bushing, the press-in pin and the bushing being designed in this way are that one formed between the press-fit pin and the socket contact area is formed by plastic deformation during the pressing process, wherein the contact area on the press-in pin and / or the bushing through an outer layer is formed. The outer layer consists of a soft, electrically conductive, metallic material.

A corresponding, electrically conductive connection is from the DE 196 09 425 A1 known. The DE 196 09 425 A1 discloses a solderless press connection between a press-in pin and a socket mounted in a circuit board opening. Such circuit boards are used, among other things, for the manufacture of electrical systems, for example in the manufacture of anti-lock braking systems (ABS). The solderless, electrical connection is made by pressing the press-in pin into the socket. During the press-in process, the contact surface of the press-in pin deforms plastically. Due to the plastic deformation, the press-in pin adapts to the contour of the inner circumferential surface of the bush.

The outer layer of the contact surface is at generic state of the art from a tin-lead alloy formed, which has a layer thickness of between 2 microns to 10 microns. With such a Contact surface texture there is a risk of tin chips coming off the press-in pin and / or of the socket, rub it into the socket when pressing in the press-in pin. This is particularly disadvantageous because the tin chips are a Bring a short circuit.

In order to avoid such chip formation, the DE 100 45 233 A1 propose to form the contact surface of the press-in pin by a scraping-resistant material layer. The scraping strength of the layer should be such that no metal chips form when pressed in. The DE 100 45 233 A1 suggests that the contact surface be nickel-plated, since nickel is too hard to be scraped off the pen. However, a contact surface designed in this way has the disadvantage that when the bushing and the press-in pin are joined together, an increased resistance in the plastic deformation of the contact surface is to be expected. This ultimately leads to the fact that a greater press-in force is required to join the press-in pin and the bushing together.

The present invention lies the problem underlying an improved, solderless electrically conductive To specify the connection between a press-in pin and a socket, in which chip formation when the press-in pin is pressed into the socket is avoided.

The basis of the invention technical problem is solved with the present invention by a electrically conductive connection between a press-in pin and a socket with the features of claim 1 solved differs from the prior art in that the soft, electrically conductive, metallic material formed outer layer is applied to a diffusion barrier layer, and that the outer layer is a Thickness between 0.1 and 0.8 μm, preferably up to 0.6 μm having.

Preferably the outer layer made of silver, a silver alloy, gold, a gold alloy, tin or a tin alloy.

The layer structure according to the invention is based on a Base material applied. The base material can be any Material that is for the production of press-fit pins and bushings in the sense of the invention suitable is. For example, copper can be used as the base material become. In the layer structure according to the invention prevents the diffusion barrier layer that the base material in the outer layer diffused. The diffusion barrier layer according to the invention accordingly represents a diffusion barrier and prevents an overlay of the outer layer through the element or elements of the base material. Through this layer structure according to the invention it ensures that the chemical composition and thus the deformation properties of the outer layer remain unchanged. This consists, for example, of tin or a tin alloy, So from a relatively soft Material that is only one of the plastic deformation when inserted opposes relatively low resistance. Since the outer layer is not The elements remain soft, thanks to the elements of the base material the outer layer also about one longer Get period, especially with regard to longer storage of the components forming the electrical connection before they are used in the production of electrically conductive systems, as well as in terms of for a release the press connection is advantageous for repair purposes.

In the case of the electrically conductive connection according to the invention, the outer layer has only a layer thickness of 0.1 μm to 0.8 μm. The thickness of the layer is preferably limited to 0.6 μm. This offers the advantage that with plastic deformation during the pressing-in process only a relatively small amount of material is available for possible chip formation, but without having to forego the desired effect of a soft, outer layer in view of the limitation of the pressing-in force. The limitation of the material thickness of the outer layer leads to that During the press-in process, no chips, but at most small bulges are formed on the contact surface. In any case, these bulges are so small that they do not protrude from the socket, but rather are held between the outer circumferential surface of the pin and the inner circumferential surface of the socket, so that there is no risk of material of the outer layer becoming detached and causing a short circuit on the printed circuit board ,

Furthermore, the present invention the advantage that the electrically conductive connection is gastight is. This advantageous effect is created by cold welding the outer layer and of the bulges at the contact surface. This also has the advantage that the connection is special durable regarding Express force or vibration load. The gas tightness protects the contact surface chemical changes, for example before oxidation by the ambient air. practical Tests have shown that the gas-tight cold welding is on the contact area Completely trained within 24 hours of press fitting is.

According to a preferred development of the present invention is at least one which forms the contact surface surface the press-in pin or the bushing before pressing in in the press-in direction convex educated. Preferably, the convexly curved contact surface on the Press-fit pin trained. With such a configuration a press connection between the press-in pin and the socket only at a defined length of the two components instead of what is favorable to the press fit necessary press force affects. They are also approaching the non-reshaped surface segments of press-fit pin and socket in the finished press connection essentially asymptotically on, causing a between the two faces continuously widening gusset is formed in which the bulge formed during the pressing process is reliably held becomes. The risk that the bulge from the created Press connection releases and possibly causing a short circuit, is thereby further decreased.

Press-in pins and are preferably Matched socket in the manner of a press fit, and the Thickness of the outer layer is at least as big as the maximum excess of the press fit, which ensures that when making the press connection just the outer layer, but not the harder Diffusion barrier layer is plastically deformed.

Further advantageous configurations of the present invention are in dependent claims 5 and 6 specified.

More details, advantages and Features of the present invention result from the following Description of an embodiment in connection with the drawing. In this show:

1 a cross section through a circuit board and a press-fit pin;

2 a cross section through a circuit board and a press-in pin inserted into the circuit board, and

3 a detailed enlargement of the in 2 represented area Z.

1 shows a cross section through a circuit board 2 , The circuit board 2 has a continuous opening 4 on, in the a socket 6 is appropriate. 1 also shows a press-in pin 8th which, over a predetermined length section L, has a surface section which is convexly curved in the press-in direction, ie in the direction of the arrow P. 10 having. This is on opposite contact legs 10a . 10b formed from the press-in pin 8th are formed in the area of the longitudinal section L, bulge outward from cylindrical longitudinal sections of the press-in pin and enclose a central cavity.

In the embodiment shown is the socket 6 made of pure copper. The base material of the pen 8th is also made of copper and shows at least in the area of the curved surface 10 an intermediate layer 11 made of nickel, on which an outer layer 13 is made of tin (cf. 3 ).

The press-in pin is used to establish the press connection 8th relative to the circuit board 2 after alignment over the socket 6 moved in the direction of arrow P. In this case, the press-in pin is first centered in the bush with its front length section, the outside diameter of which is smaller than the inside diameter of the bush. As the movement progresses in the press-in direction, the curved longitudinal section finally arrives 10 into the socket 6 , Here, the distance between the outer circumferential surface of the press-in pin initially decreases 8th and the inner peripheral surface 12 the socket 6 until both surfaces come into contact. As the movement progresses in the pressing direction, the contact legs become 10a . 10b initially elastically radially inwards, as the movement progresses, the material of the outer layer is finally plastically deformed. It becomes with the progressive press-in movement from the outer peripheral surface of the press-in pin 8th sheared, and it forms between the rear flank of the curvature in the pressing direction 10 and the inner peripheral surface 12 the socket 6 a bulge 14 out. The press connection produced in this way is, on the one hand, due to elastic restoring forces of the radially inwardly biased contact legs 10a . 10b kept to Others by cold welding between the press-in pin 8th and the socket 6 ,

As in the schematic representation 3 can be seen, this bulge 14 predominantly between the inner peripheral surface 12 the socket 6 and the outer peripheral surface of the pin 8th held, and the bulge 14 is inside the socket 6 , ie it does not protrude in the axial direction. The longitudinal extent of the curved surface section is preferred for this 10 smaller than the longitudinal extension of the socket 6 selected. Positioning measures also ensure that after the press connection is established, the curved surface area 10 with its meridian located approximately half the axial length of the socket.

2

circuit board

4

opening

6

Rifle

8th

Insert pin

10

convex domed contact area

10a,

b contact leg

11

interlayer

12

Inner circumferential surface

13

Outer layer

14

bulge

P

press-in

L

longitudinal section

Claims (6)

Electrically conductive connection between a press-in pin ( 8th ) and a socket ( 6 ), the press-in pin ( 8th ) and the socket ( 6 ) are designed so that one between the press-in pin ( 8th ) and the socket ( 6 ) formed contact surface ( 10 ) is formed by plastic deformation during the press-in process, the contact surface ( 10 ) on the press-in pin ( 8th ) and / or the socket ( 6 ) by an outer layer ( 13 ) is formed, which is formed from a soft, electrically conductive, metallic material, characterized in that the outer layer ( 13 ) on a diffusion barrier layer ( 11 ) is applied, and that the outer layer ( 13 ) has a thickness between 0.1 to 0.8 μm, preferably up to 0.6 μm. Electrically conductive connection according to claim 1, characterized in that the outer layer ( 13 ) is formed from silver, a silver alloy, gold, a gold alloy, tin or a tin alloy. Electrically conductive connection between a press-in pin ( 8th ) and a socket ( 6 ) according to claim 1 or 2, characterized in that at least one the contact surface ( 10 ) forming surface of the press-in pin ( 8th ) or the socket ( 6 ) is convexly curved before being pressed in in the pressing direction (P). Electrically conductive connection between a press-in pin ( 8th ) and a socket ( 6 ) according to one of claims 1, 2 or 3, characterized in that press-in pin ( 8th ) and socket ( 6 ) are matched to each other like a press fit and that the thickness of the outer layer ( 13 ) is at least as large as the maximum interference fit. Electrically conductive connection between a press-in pin ( 8th ) and a socket ( 6 ) according to one of the preceding claims, characterized in that the diffusion barrier layer ( 11 ) is made of a harder material than the outer layer ( 13 ). Electrically conductive connection between a press-in pin ( 8th ) and a socket ( 6 ) according to one of the preceding claims, characterized in that the diffusion barrier layer ( 11 ) is made of nickel.