ELECTRICAL CONTACT ELEMENT, PRESS-IN PIN, BUSHING, AND LEADFRAME

Abstract

An electrical contact element includes a base body and a coating covering the base body at least in sections. The coating includes an inner layer and an outer layer. The inner layer is applied to the base body and the outer layer is applied to the inner layer and forms a surface at least in sections of the electrical contact element. The inner layer is made of tin and the outer layer of silver, and the outer layer has a thickness of 50 nm-5.0 μm.

Claims

1. An electrical contact element comprising: a base body comprising a base body section; a coating covering the base body section, the coating comprising an inner layer and an outer layer, the inner layer applied on the base body section, the inner layer comprising tin, the outer layer applied on the inner layer and defining a surface of the electrical contact element the outer layer comprising silver and an outer layer thickness of 50 nm to 5.0 μm.

2. The electrical contact element as claimed in claim 1, wherein the outer layer thickness is 75 nm-2.5 μm.

3. The electrical contact element as claimed in claim 1, wherein the inner layer comprises pure tin or the outer layer comprises pure silver.

4. The electrical contact element as claimed in claim 1, wherein the inner layer comprises an inner layer thickness of 0.5 μm-10.0 μm.

5. The electrical contact element as claimed in claim 1, further comprising a contacting section, the contacting section for making an electrical contact with a second electrical contact element, wherein the coating is applied on the contacting section.

6. The electrical contact element as claimed in claim 1; wherein the base body comprises copper, a copper based alloy, bronze, or a copper-nickel-silicon alloy.

7. The electrical contact element as claimed in claim 1; wherein the inner layer or the outer layer is a galvanic deposition layer.

8. The electrical contact element as claimed in claim 1, wherein the base body comprises a nickel layer, wherein the inner layer is applied on the nickel layer.

9. The electrical contact element as claimed in claim 1, wherein the electrical contact element is a press-in pin, a press-fit contact, or an electrically conductive bushing.

10. A press-in pin that for pressing into a bushing; the press-pin comprising: a base body comprising a base body section; a coating covering the base body section, the coating comprising an inner layer and an outer layer, the inner layer applied to the base body section, the inner layer comprising tin, the outer layer applied to the inner layer and defining a surface of the electrical contact element, the outer layer comprising silver; and an intermix comprising the inner layer and the outer layer, the intermix resulting from pressing the press-in pin into the bushing.

11. A bushing for receiving a press-in pin, the hushing comprising: a base body comprising a base body section; a coating covering the base body section, the coating comprising an inner layer and an outer layer, the inner layer applied to the base body section, the inner layer comprising tin, the outer layer applied to the inner layer and defining a surface of the electrical contact element, the outer layer comprising silver; and an intermix comprising the inner layer and the outer layer, the intermix resulting from pressing the press-in pin into the bushing.

12. A leadframe comprising: a frame member defining a contacting recess or a contacting through-going opening, the frame member comprising an inner circumferential surface, the inner circumferential surface delimiting the contacting recess or the contacting through-going opening, and a coating covering a section of the inner circumferential surface, the coating comprising an inner layer and an outer layer, the inner layer applied on the section, the inner layer comprising tin, the outer layer applied on the inner layer and defining a contacting area; the outer layer comprising silver and an outer layer thickness of 50 nm to 5.0 μm.

13. The leadframe as claimed in claim 12, wherein the outer layer thickness is 75 nm-2.5 μm.

14. The leadframe as claimed in claim 12, wherein the inner layer comprises pure tin or the outer layer comprises pure silver.

15. The leadframe as claimed in claim 12, wherein when the frame member is the contacting recess the contact recess comprising a base, the coating covering a portion of the base.

16. The electrical contact element as claimed in claim 1, wherein the outer layer thickness is 80 nm-1.0 μm.

17. The electrical contact element as claimed in claim 1, wherein the outer layer thickness is 90 nm-500 nm.

18. The electrical contact element as claimed in claim 1, wherein the outer layer thickness is 100 nm-200 nm.

19. The electrical contact element as claimed in claim 1, wherein the inner layer comprises pure tin.

20. The electrical contact element as claimed in claim 1, wherein the outer layer comprises pure silver.

Description

BRIEF DESCRIPTION OF THE INVENTION

[0027] The invention is further explained hereinunder with the aid of exemplary embodiments and with reference to the attached drawings together with further details.

[0028] In the drawings:

[0029] FIG. 1 illustrates an electrical contact element in accordance with the invention, embodied as a press-in pin;

[0030] FIG. 2 illustrates an electrical contact element in accordance with the invention, embodied as an electrically conductive bushing; and

[0031] FIG. 3 illustrates a leadframe in accordance with the invention.

DETAILED DISCUSSION OF THE INVENTION

[0032] Identical reference numerals are used hereinunder for like and like-functioning parts.

[0033] FIG. 1 illustrates an electrical contact element 10′ that is embodied as a press-in pin. The electrical contact element 10′ comprises a base body 11 having a press-in section 13 that is embodied in the form of two arms 15 that are separated by means of an intermediate space 14. The press-in section 13 is embodied in a flexible manner.

[0034] The base body 11 is covered in sections by a coating 12, wherein the coating 12 comprises an inner layer 21 and an outer layer 22. The inner layer 21 is applied to the base body 11 and the outer layer 22 is applied to the inner layer 21. The outer layer 22 of the coating 12 forms at least in sections a surface or portion of the surface 16 of the electrical contact element 10′. The illustrated thickness ratios of the coating 12 in relation to the base body 11 are provided merely for explanation purposes and are not to be regarded as being to scale.

[0035] The inner layer 21 is formed from pure tin and the outer layer 22 is formed from silver. The outer layer 22 comprises a thickness of 100 nm to 200 nm. The coating 12 is shown in the illustrated example only in the region of the press-in section 13. As an alternative, it is also possible for the coating 12 to completely cover the base body 11. The press-in section 13 is used as a contacting section for making electrical contact with a further electrical contact element, wherein in the present case the further electrical contact element is preferably a bushing or a contacting recess or a contacting through-going opening.

[0036] Furthermore, the press-in section 13 can comprise an under-layer of nickel so that a nickel layer is provided under the coating 12, in particular under the inner layer 21. The base body 11 can accordingly comprise in the press-in section 13 a nickel layer (not illustrated) and the inner layer 21 is applied to said nickel layer.

[0037] As the press-in pin 10′ is pressed in, the resultant prevailing pressure loading causes the thin outer layer 22 and the soft inner layer 21 to mix with one another at least in sections. Silver particles of the outer layer 22 are accordingly pressed into the inner layer 21. The formation of whiskers is prevented by virtue of the embodiment in accordance with the invention of the electrical contact element 10′.

[0038] The base body 11 is preferably formed from copper or from a copper-based alloy. In the sections of the electrical contact element 10′ that have not been provided with a coating 12, the surface 16 is formed by means of the base body 11 and its material.

[0039] The inner layer 21 and the outer layer 22 are applied using galvanic methods, preferably in a galvanic strip production system in which by way of example one stamped frame that is essentially strip-shaped in which the press-in pins are held in a state in which they are not yet fully stamped out is drawn through multiple successive cells.

[0040] FIG. 2 illustrates an electrical contact element 10″ in accordance with the invention that is embodied as an electrically conductive bushing. The electrical contact element 10″ comprises a base body 11 that has a hollow cylindrical shape. It likewise illustrates the inner circumferential surface 17 and the outer circumferential surface 18. It is possible to insert by way of example a press-in pin into the hollow chamber 19. The base body 11 is covered on the inner circumferential surface 17 completely or to its full circumferential extent by a coating 12, wherein the coating 12 comprises an inner layer 21 and an outer layer 22, wherein the inner layer 21 is applied to the base body 11, in particular to the inner circumferential surface 17 of the base body 11, and the outer layer 22 is applied to the inner layer 21. The outer layer 22 forms at least in sections a portion of the surface 16 of the electrical contact element 10″. The outer circumferential surface 18 is likewise embodied as a portion of the surface 16 of the electrical contact element 10″. In addition, it is conceivable to provide an under-layer of nickel to the coating 12. For this purpose, the base body 11 could comprise a nickel layer to which the coating 12 is applied.

[0041] The inner layer 21 is formed from pure tin and the outer layer is formed from silver, wherein the outer layer 22 has a thickness of 50 nm to 5.0 μm. So as to make electrical contact with a further electrical contact element, such as for example a press-in pin, the electrical contact element 10″ comprises a contacting section 20. In the present case, said contacting section is entirely the outermost layer of the coating 12 or of the electrical contact element 10″, said outermost layer being the layer that faces in the direction of the hollow chamber 19. The contacting section 20 is fully covered by the coating 12. As the press-in pin is pressed in, the thin outer layer 22 of silver and the soft inner layer 21 of tin are mixed with one another at least in sections as a result of the then prevailing pressure loading. Silver particles from the outer layer 22 are accordingly pressed into the inner layer 21. The formation of whiskers is prevented by virtue of the embodiment in accordance with the invention of the electrical contact element 10″.

[0042] FIG. 3 illustrates a leadframe 30 that is embodied in accordance with the invention. Said leadframe comprises a contacting recess 31 and a contacting through-going opening 32. Both the contacting recess 31 and also the contacting through-going opening 32 are delimited or formed by an inner circumferential surface 17. The inner circumferential surfaces 17 are in each case provided with a coating 12, wherein the coatings 12 comprise an inner layer 21 and an outer layer 22. The inner layers 21 are applied to the inner circumferential surfaces 17 and the outer layers 22 are applied to the inner layers 21.

[0043] In the non-coated state, the inner circumferential surfaces 17 of the contacting through-going opening 32 and the contacting recess 31 are formed by means of leadframe material. After having been coated, the outer layers 22 of the coatings 12 form the actual outermost layers of the contacting recess 31 and also of the contacting through-going opening 32, wherein the outermost layers are always understood to be those layers that form an outer surface in terms of a contacting area 33. The contacting areas 33 are accordingly formed in accordance with FIG. 3 in each case by the outermost layer 22 of the coating 12.

[0044] In the case of the contacting recess 31, it is furthermore possible to provide that the base 34 of the contacting recess 31 is likewise a coating 12 having an inner layer 21 and an outer layer 22. The inner layers 21 are formed from pure tin and the outer layers 22 are formed from silver.

[0045] It is to be mentioned at this point that all elements and components that are described above in connection with the embodiments in accordance with FIG. 1 to FIG. 3 when regarded individually or in any combination, in particular the details illustrated in the drawings, are claimed as essential for the invention.

LIST OF REFERENCE NUMERALS

[0046] 10′, 10″ Electrical contact element

[0047] 11 Base body

[0048] 12 Coating

[0049] 13 Press-in section

[0050] 14 Intermediate space

[0051] 15 Arm

[0052] 16 Surface

[0053] 17 Inner circumferential surface

[0054] 18 Outer circumferential surface

[0055] 19 Hollow chamber

[0056] 20 Contacting section

[0057] 21 Inner layer

[0058] 22 Outer layer

[0059] 30 Leadframe

[0060] 31 Contacting recess

[0061] 32 Contacting through-going opening

[0062] 33 Contacting area

[0063] 34 Base