Cable connector for coaxial cable on thick printed-circuit board

Abstract

Method for connecting a printed circuit board (1) to a coaxial cable (3), wherein the coaxial cable (3) has an internal conductor (5) which is surrounded by a dielectric (7) which, in turn, is surrounded by a shield (6), wherein the dielectric (7) is surrounded by an outer casing (4), wherein the internal conductor (5) is soldered to a contact point (8) on the printed circuit board (1) for the purpose of making electrical contact, characterized in that the printed circuit board (1) has a recess (2) which starts from the surface of said printed circuit board, and the end region of the outer casing (4) of the coaxial cable (3) is inserted at least partially into the recess (2).

Claims

1. A method of connecting a first contact point on a face of a printed-circuit board having an outer edge to a coaxial cable having a core conductor surrounded by a dielectric inner sheath surrounded by a conductive shield surrounded by an outer sheath, the method comprising the steps of sequentially: milling in the board adjacent between the contact point and the outer edge a recess opening at the face and of a semicircular shape of a diameter less than an outer diameter of the outer sheath; forming a second contact point in the recess; stripping the inner sheath, outer shield, and outer sheath from an end of the cable to expose an end of the core conductor; stripping the outer sheath outward of the exposed end of the core conductor to expose the outer shield; pressing the end of the cable into the recess in a form fit and thereby engaging the exposed core-conductor end with the first contact point and the exposed shield with the second contact point; and electrically attaching the exposed core-conductor end and the exposed shield to the respective contact points.

2. The method according to claim 1, wherein the width of the recess is slightly smaller than an outer diameter of the outer sheath of the coaxial cable and the end of the cable is pressed at least partially into the recess.

3. The method according to claim 1, wherein the recess is formed in the printed-circuit board starting from the outer edge of the printed-circuit board.

4. The method according to claim 1, wherein a depth of the recess in the printed-circuit board is set to be greater than at least half an outer diameter of the outer sheath of the coaxial cable.

5. The method according to claim 1, wherein a depth of the recess in the printed-circuit board is selected to be smaller than a thickness of the printed-circuit board.

6. The method according to claim 1, further comprising the step of: providing the recess and a partial region around the recess with a cover.

7. The method according to claim 6, wherein the cover is a separate component and is secured to the printed-circuit board after insertion of the coaxial cable into the recess and at least after electrically attaching the core conductor to the contact point on the printed-circuit board.

8. The method according to claim 1, wherein the recess in the printed-circuit board has a length that corresponds to a sum of a length of the exposed core conductor, a length of the exposed dielectric inner sheath, a length of the exposed shield and a partial length of the outer sheath of the coaxial able.

9. The method defined in claim 1, wherein the exposed core-conductor end and the exposed shield are electrically attached to the respective contact points by soldering.

10. The method defined in claim 1, wherein the shield is electrically attached to the further contact point by soldering.

11. A connection assembly between a coaxial cable and a printed-circuit board made according to the method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) An embodiment produced according to the method according to the invention is explained in more detail below and described with reference to the figures in which:

(2) FIGS. 1 and 2 are perspective views of circuit boards for two respective embodiments of the invention;

(3) FIG. 3 is a top view of the assembly of circuit board and coaxial cable;

(4) FIG. 3 shows the assembly of FIG. 3 in a perspective view;

(5) FIG. 4 is a partly sectional end view of the invention with a cover on one face of the circuit board; and

(6) FIG. 5 is a section perpenticular to that of FIG. 6 of the invention with the cover on both faces of the circuit board.

SPECIFIC DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows part of a printed-circuit board 1 of an electronic device not illustrated in more detail. Electrical and electronic components for realizing the function of the electronic device are mounted on the printed-circuit board 1 in a conventional manner. The printed-circuit board 1 is held inside a housing (not illustrated) of the electronic device. According to the invention, a recess 2 is formed in this printed-circuit board, starting from an edge of the printed-circuit board 1. The depth of the recess 2 corresponds approximately to half the thickness of the printed-circuit board 1. The recess 2 is milled by a stub-milling machine and has a predetermined length, a predetermined depth and a predetermined width. Its cross-section is approximately rectangular in this case.

(8) FIG. 2 shows an alternative configuration of the recess 2 milled into the printed-circuit board 1 by a ball-type milling machine. The recess 2 also has a predetermined width and a predetermined length and depth here, so a semicircular cross-section of the recess 2 is produced owing to the use of a ball-type milling machine.

(9) Whereas FIGS. 1 and 2 show that, starting from the edge of the printed-circuit board 1, each recess 2 extends inward and can also be milled into the surface of the printed-circuit board 1 within the inner region of the printed-circuit board 1 and thereby at a spacing from the edge of the printed-circuit board 1.

(10) FIG. 3 shows, in a plan view of the printed-circuit board 1 from above, the arrangement of an appropriately prepared coaxial cable 3 in the recess 2.

(11) FIG. 4 shows the same structure as in FIG. 3, but in a perspective view of the printed-circuit board 1 from the side.

(12) Common to the embodiments according to FIGS. 3 and 4 is that the coaxial cable 3 has an outer sheath 4 in a manner known per se, and a core conductor 5 (for example an electrically conductive wire) coaxially inside it. A shield 6, for example a foil or a mesh made from aluminum, is located beneath the outer sheath 4. So that the electrically conductive shield 6 does not come into contact with the core conductor 5, a dielectric inner sheath 7, for example made from a plastics material, is provided between the core conductor 5 and the shield 6. Such a construction of the coaxial cable 3 is essentially known.

(13) The correspondingly prepared end of the coaxial cable 3 is inserted into the recess 2 that was previously formed in the printed-circuit board 1. For this purpose, the core conductor 5 is exposed by removal of the outer sheath 4, the shield 6 and the dielectric inner sheath 7 to a predetermined length.

(14) The dielectric inner sheath 7 is then exposed in that the shield 6 surrounding it and the outer sheath 4 are removed. Moreover, the shield 6 is exposed to a predetermined length in that the outer sheath 4 is removed. The thus-prepared end of the coaxial cable is then fitted into the recess 2 in such a way that an end of the outer sheath 4 shown at 4 in FIGS. 3 and 4, is inserted, in particular pressed, into the recess. As a result of the outer diameter of the core conductor 5 and the shield 6 and the dielectric inner sheath 7 being smaller than the width or depth of the recess 2, these regions of the coaxial cable 3 are at a spacing from the recess 2.

(15) FIG. 4 shows that there is on of the printed-circuit board 1 at least one contact point 8 (also referred to as a solder pad), preferably precisely one contact point, and at least one contact point 9, preferably one contact point 9, on the one side of the recess 2 or two contact points are present on both sides of the recess 2 on the surface of the printed-circuit board 1. The core conductor 5 and/or the shield 6 of the coaxial cable 3 are electrically contacted via these contact points 8, 9, for example as a result of a soldering procedure.

(16) It can be seen in particular in FIG. 4 that the end of the outer sheath 4 shown at 4 is provided with its longitudinal axis approximately in the longitudinal axis of the recess 2, and the longitudinal axes of the core conductor 5, the shield 6 and the dielectric inner sheath 7 are offset from this longitudinal axis of the recess 2. This means that the end of the coaxial cable is bent slightly upward to ensure that the core conductor 5 can lie on the contact point 8.

(17) In FIGS. 5 and 6, a cover 10 is illustrated that covers the end of the coaxial cable 3 in the recess 2. In one variant, the cover 10 is mounted only on one face of the printed-circuit board 1. However, it is also conceivable for the cover 10 to be symmetrical, or deviate from a symmetrical configuration on both faces of the printed-circuit board 1.

(18) In the embodiment according to FIGS. 5 and 6, the cover 10 is provided asymmetrically on both faces of the printed-circuit board 1.

(19) The cover 10 comprises an upper side 11 that has a web 12 (or a plurality of webs 12, as can be seen in FIG. 6) extending toward the face of the printed-circuit board 1. A front web 13 can be present, but does not have to be present, which front web is aligned parallel to the lateral edge of the printed-circuit board 1 from which the recess 2 starts (FIG. 6). The upper side 11 of the cover 10 covers at least the parts of the coaxial cable 3 inserted into the recess 2, but preferably also extends beyond them.

(20) To secure the cover 10, it has, in a suitable manner, a latch hook 14 (possibly also more than one latch hook 14), that secures the cover 10 to the printed-circuit board 1.

(21) In the illustrated embodiment of the cover 10, the front web 13 has an opening for the coaxial cable, so that it is not only conceivable to secure the cover 10 by its at least one latch hook 14 latching against the printed-circuit board 1, but alternatively to push the cover 10 onto the printed-circuit board 1, to which end the latch hook 14 is formed as a guide element. Primarily, the at least one web 12 that acts (in particular presses) on the end of the outer sheath 4 serves for mechanical securing and thereby, in an advantageous manner, strain relief.

(22) Whereas the cover 10 illustrated in FIGS. 5 and 6 is produced as a separate component and then assembled, it is conceivable to protect the region of the recess 2, with the coaxial cable 3 arranged and contacted therein, by a potting compound, for example, and to possibly also thus achieve strain relief.

(23) A brief, paraphrased description of the invention follows:

1 Problem

(24) The direct assembly of coaxial cables on printed-circuit board material via a manual soldering procedure is imprecise and is not defined in the high frequency range. Continuous milling in the printed-circuit board material does not enable additional space-saving strain relief.

2 Solution Principle

(25) By partially milling a suitable thick printed-circuit board to approximately half the cable diameter, the cable end can be positioned in a defined manner on the printed-circuit board and the electrical conductor of the cable can be soldered in a defined manner to a contact point, in particular to an end of a trace on the printed-circuit board. In addition, the partial milling of the printed-circuit board furthermore enables a mechanical counter-pressure of an add-on part against the cable sheath for strain relief.

3 Implementation

(26) The printed-circuit board is milled to the length of the bared dielectric inner sheath of the coaxial cable. The milling width corresponds to the diameter of the coaxial line. The milling depth corresponds approximately to the external radius of the coaxial line, and it should be ensured here that the milling depth is sufficient to hold the width of the coaxial cable tightly in the printed-circuit board. At the milling edge, solder pads are applied laterally level with the bared cable shield in order to ensure the ground connection of the coaxial cable. The projecting core conductor is soldered to a further solder pad. A cover is preferably additionally used that has at least one rib that, in the assembled state, fits around the coaxial line from above and additionally fixes it in the milled recess.

4 Sequence

(27) 1) The milled recess is taken into account in the printed-circuit board design 2) The coaxial cable is inserted into the milled portion during cable connection 3) The cable is inserted flush so that the dielectric inner sheath abuts the end of the milled portion 4) The cable is held in the milled portion by a holding device 5) The cable is soldered 6) Strain relief is ensured by a holding device on an add-on part

5 Use

(28) Assembly of antennae that: demands precise processes owing to the high frequencies are soldered automatically must ensure strain relief on the cable

(29) By partially milling a suitable thick printed-circuit board to approximately half the cable diameter, the cable end can be mounted in a defined manner on the printed-circuit board and the electrical conductor of the cable can be soldered in a defined manner to a contact point, in particular to an end of a trace, on the printed-circuit board.

(30) TABLE-US-00001 List of references 1 Printed-circuit board 2 Recess 3 Coaxial cable 4 Outer sheath 5 Core conductor 6 Shield 7 Dielectric inner sheath 8 Contact point 9 Contact point 10 Cover 11 Upper side 12 Web 13 Front web 14 Latch hook