Press-in pin and method for producing same

Abstract

The disclosure relates to a press-in pin having a tin-free and lead-free surface coating. The press-in pin also has an outer second coating. By suitable treatment after the outer second coating has been applied to the first coating, a transition layer is formed between the first coating and the outer second coating.

Claims

1. A press-in pin for being pressed into a contact hole, the press-in pin comprising a press-in zone, the press in zone including a first coating made of gold or of a gold alloy or of silver or of a silver alloy or of copper, or of aluminum, on which an outer second coating is applied, wherein a transition layer is formed between the first coating and the outer second coating, and further wherein the outer second coating is an organic layer, and the transition layer is formed after applying the organic layer to the first coating, and wherein the organic layer is an organic surface protection, and wherein the transition layer is an oxidation or diffusion layer.

2. The press-in-pin according to claim 1, wherein the outer second coating is mechanically and/or chemically bonded to the first coating and the transition layer is formed subsequently.

3. The press-in-pin according to claim 1, wherein the transition layer is formed by a chemical, a mechanical and/or a thermal treatment.

4. An electrical contacting with the contact hole into which the press-in pin is pressed according to claim 1.

5. The electrical contacting according to claim 4, wherein the contact hole comprises a coating made of gold or a gold alloy, of silver or a silver alloy or of copper or tin, preferably with an additional coating against oxidation.

6. The electrical contacting according to claim 4, wherein the electrical contacting is gas-tight.

7. An electric conductor plate or electric lead frame with the electrical contacting according to claim 4.

8. A method of producing a press-in pin having a press-in zone for being pressed into a contact hole, comprising: applying a first coating made of gold or gold alloy or of silver or a silver alloy or of copper or of aluminum to the press-in zone; applying a second coating on the first coating, wherein the second coating is an organic layer which forms an organic surface protection; and subsequently forming a transition layer between the first coating and the second coating, wherein the transition layer is an oxidation or diffusion layer.

9. The method according to claim 8, wherein the transition layer is formed chemically, mechanically and/or thermally.

Description

(1) Preferred examples of the disclosure are explained in more detail in the following using schematic drawings. They show:

(2) FIG. 1 shows a schematic diagram of a contacting according to the disclosure.

(3) FIG. 2 shows a schematic sectional view of the layer structure of a press-in pin according to the disclosure before the formation of a transition layer, and

(4) FIG. 3 shows a schematic cross-section of a press-in pin according to the disclosure.

(5) FIG. 1 shows a schematic diagram of a contacting 1 according to the disclosure, which is executed in press-in technology. A press-in pin 2 is pressed into a contact hole 4 of a printed circuit board 6. In the example shown in FIG. 1, the press-in pin 2 is realized with two legs 8, 10, which are arched in shape and which extend away from a pin body 12 towards a pin head 14. Of course, the press-in pin 2 can also be realized in other ways.

(6) The contact hole 4 is provided with a suitable coating consisting of gold or a gold alloy, silver or a silver alloy, copper or a copper alloy or tin, for example. A multi-layer structure is also possible.

(7) The basic material of the press-in pin 2 consists, for example, of an aluminum-based or copper-based alloy. This base material is then coated in the manner described below. FIGS. 2 and 3 show the layer structure of a press-in zone 16 of the press-in pin 2.

(8) A contact area 20 provides the electrical contact between press-in pin 2 and contact hole 4 (e.g. printed circuit board hole). The press-in zone 16 formed by the two legs 8, 10, on which the contact area 20 is also formed, provides a force-locking connection between the press-in pin 2 and the contact hole 4. The connection between press-in pin 2 and contact hole 4 is gas-tight.

(9) The press-in zone 16 of the press-in pin 2 has a first coating 22 made of gold or a gold alloy, of silver or a silver alloy, of copper or of aluminum as shown in FIG. 2, on which an additional second coating 24 is applied. This additional coating can, for example, be applied mechanically or chemically (by deposition) to the first coating 22. This second coating 24 is preferably an organic layer which forms an organic surface protection. Such organic solderability preservatives are known in printed circuit board technology under the abbreviation OSP, so that further explanations are unnecessary.

(10) This intermediate product of a press-in-pin 4 provided with a first coating 22 and a second coating 24, preferably with an organic coating, is shown in FIG. 2. This intermediate product corresponds more or less to the prior art described above.

(11) According to the disclosure, a transition layer 26 shown in FIG. 3 is then formed on the intermediate product by suitable mechanical, thermal and/or chemical treatment. This transition layer 26 is formed in the interface layer region between the first coating 22 and the second coating 24 and can be formed by diffusion or oxidation processes, by chemical reactions or in any other way, depending on process control and choice of material.

(12) This layer/layer structure formed in this way serves on the one hand as protection against oxidation and on the other hand to reduce the press-in forces when pressing the press-in pin into the contact hole so that damage to the printed circuit board 6 or the lead frame is avoided.

(13) A sufficiently high holding force is guaranteed by the clamping force of the press-in zone 16 of the press-in pin 2 and by frictional locking between the contact area 20 and the contact hole 4.

(14) The contact hole 4 has, as explained, a coating made of gold or a gold alloy, or of silver or a silver alloy, or of copper, preferably with an additional coating against oxidation, thereby reducing whiskers. Optionally, the contact hole can also be coated with tin.

(15) Al-based or Cu-based alloys can be used as materials for the press-in pin 2.

(16) A press-in pin is disclosed, wherein the pin material has two surface coatings between which a transition layer is formed.

LIST OF REFERENCE SIGNS

(17) 1 contacting 2 press-in pin 4 contact hole 6 printed circuit board/lead frame 8 leg 10 leg 12 pin body 14 pin head 16 press-in zone 18 coating contact hole 20 contact area 22 first coating 24 second coating 26 transition layer