Method for providing an electrical connection and printed circuit board

Abstract

Method for providing an electrical connection, comprising connecting a first cable to a first conducting structure on a printed circuit board, connecting a second cable to a second conducting structure on the printed circuit board, comparing a propagation delay of a first signal path comprising the first cable and the first conducting structure on the printed circuit board, and a propagation delay of a second signal path comprising the second cable and the second conducting structure on the printed circuit board; and removing conductive material of the first conducting structure and/or of the second conducting structure, in order to modify an electrical length of the first conducting structure and/or of the second conducting structure, to obtain a first conducting path and a second conducting path, in dependence on a result of the comparison, in order to reduce a difference of the propagation delays between the first signal path and the second signal path.

Claims

1. A electronic device comprising a first contact pad for receiving a first signal from a first cable; a second contact pad for receiving a second signal from a second cable; a third contact pad contacting a device; a fourth contact pad contacting the device; a first conducting path connecting the first contact pad and the third contact pad, wherein the first conducting path comprises a first non-removable conductor and a first removable conductor; and a second conducting path connecting the second contact pad and the fourth contact pad, wherein the second conducting path comprises a second non-removable conductor and a second removable conductor, wherein the first and the second removable conductors are configured to compensate for a propagation delay difference between the first and the second signals through the first and the second conducting paths by removal of the first and the second removable conductors respectively; wherein a shape of the first removable conductor and a shape of the second removable conductor are trapezoidal, wherein a shape of the first non-removable conductor is continuous and comprises uniform thickness, wherein the first non-removable conductor comprises an indentation, and wherein the first non-removable conductor fits within a recess created by the indentation in the first non-removable conductor.

2. The electronic device according to claim 1, wherein the second non-removable conductor comprises a linear continuous shape of uniform thickness, and wherein the second non-removable conductor extends out from the non-removable portion.

3. The electronic device according to claim 1, wherein first removable conductor on the first conducting path is offset from the second removable conductor on the second conducting path.

4. The electronic device according to claim 1, further comprising a connector connected to the third contact pad and the fourth contact pad, wherein the connector is configured to connect to a board.

5. The electronic device according to claim 1, wherein a free end of the first cable is attached to a connector, and wherein a free end of the second cable is attached to the connector.

6. The electronic device according to claim 2, further comprising a first area and a second area, wherein the first area in the first conducting path is operable to be formed by removal of the first removable conductor by one or more of a laser ablation, milling, routing or etching and is located closer to a cable-sided edge of the electronic device than the second conducting path from the second area operable to be formed by removal of the second removable conductor by one or more of a laser ablation, milling, routing or etching.

7. A printed circuit board comprising: a first contact pad contacting a first cable; a second contact pad contacting a second cable; a third contact pad contacting a device; a fourth contact pad contacting the device; a first conducting structure forming a first conducting path connecting the first contact pad and the third contact pad, wherein the first conducting structure comprises a first non-removable conductor and a first removable conductor; and a second conducting structure forming a second conducting path connecting the second contact pad and the fourth contact pad, wherein the first conducting structure and the second conducting structure are configured to avow modification of a propagation delay by definition of shapes of the first conducting path and second conducting path; wherein the second conducting structure comprises a second non-removable conductor and a second removable conductor, wherein a shape of the first removable conductor and a shape of the second removable conductor are trapezoidal, wherein a shape of the first non-removable conductor is continuous and comprises uniform thickness, wherein the first non-removable conductor comprises an indentation, and wherein the first non-removable conductor fits within a recess created by the indentation in the first non-removable conductor.

8. The printed circuit board according to claim 7, wherein a first design reference line along which the first contact pad and the second contact pad are aligned is parallel to a second design reference line along which the third contact pad and the fourth contact pad are aligned.

9. The printed circuit board according to claim 7, wherein the first removable conductor and the second removable conductor are configured to allow for a removal of conductive materials of the first removable conductor and the second removable conductor respectively by one or more of a laser ablation, milling or etching wherein the shape and an electrical length of the first conducting path and the shape and an electrical length of the second conducting path are defined by the removal of the conductive materials.

10. The printed circuit board according to claim 7, wherein the first cable and the second cable are coaxial cables.

11. The printed circuit board according to claim 7, wherein the propagation delay is determined by time domain reflectometry measurements (TDR).

12. The printed circuit board according to claim 7, wherein a conductive material of the second removable conductor is operable to be removed subsequent to a definition of the second conducting structure to define the second conducting path so that a propagation delay difference of signal paths comprising the first conducting path with the first cable and the second conducting path with the second cable is at least partially compensated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the invention are described with reference to the following drawings, in which:

(2) FIG. 1 shows a block diagram of a method for providing an electrical connection according to an embodiment of the present invention;

(3) FIG. 2 shows a schematic view of a printed circuit board according to an embodiment of the present invention;

(4) FIG. 3 shows a schematic view of a printed circuit board with 13 conducting paths according to an embodiment of the present invention;

(5) FIG. 4 shows a schematic view of a printed circuit board with a first conducting path and a second conducting path after processing according to an embodiment of the present invention;

(6) FIG. 5 shows a schematic view of a printed circuit board with a first conducting path and a second conducting path before processing according to an embodiment of the present invention;

(7) FIG. 6 shows a schematic view of a first conducting path and a second conducting path with an illustration of the processing according to an embodiment of the present invention;

(8) FIG. 7a shows a schematic view of a printed circuit board with a first conducting path and a second conducting path before processing according to an embodiment of the present invention;

(9) FIG. 7b shows a schematic view of a printed circuit board with a first conducting path and a second conducting path with an illustration of the processing according to an embodiment of the present invention;

(10) FIG. 7c shows a schematic view of a printed circuit board with a first conducting path a second conducting path after processing according to an embodiment of the present invention;

(11) FIG. 8 shows a printed circuit board with a different layout for the first conducting path according to an embodiment of the present invention;

(12) FIG. 9a shows a sharp-angle shaped conducting path for a printed circuit board according to an embodiment of the present invention;

(13) FIG. 9b shows a trapezoidal shaped conducting path for a printed circuit board according to an embodiment of the present invention;

(14) FIG. 9c shows a hexagonal shaped conducting path for a printed circuit board according to an embodiment of the present invention;

(15) FIG. 9d shows a rippled/meander shaped conducting path for a printed circuit board according to an embodiment of the present invention; and

(16) FIG. 9e shows a circular/meander shaped conducting path for a printed circuit board according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(17) Equal or equivalent elements or elements with equal or equivalent functionality are denoted in the following description by equal or equivalent reference numerals even if occurring in different figures.

(18) In the following description, a plurality of details is set forth to provide a more throughout explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form rather than in detail in order to avoid obscuring embodiments of the present invention. In addition, features of the different embodiments described herein after may be combined with each other, unless specifically noted otherwise.

(19) FIG. 1 shows a block diagram of a method 100 for providing an electrical connection. The method 100 comprises the step connecting 110 a first cable to a first conducting structure on a printed circuit board, connecting 120 a second cable to a second conducting structure on the printed circuit board and comparing 130 a propagation delay of a first signal path comprising the first cable and the first conducting structure on the printed circuit board, and a propagation delay of a second signal path comprising the second cable and the second conducting structure on the printed circuit board. Furthermore, the method 100 can comprise the step removing 140 conductive material of the first conducting structure and/or of the second conducting structure, in order to modify an electrical length of the first conducting structure and/or of the second conducting structure, to obtain a first conducting path and a second conducting path, in dependence on a result of the comparison, in order to reduce a difference of the propagation delays between the first signal path and the second signal path.

(20) Optionally, the propagation delays of the first and second signal paths can be determined 125 by time domain reflectometry measurement before comparing the propagation delay of the first signal path and the propagation delay of the second signal path.

(21) Optionally, a propagation delay difference from the propagation delays of the first and second signal paths can be determined 132, wherein based on the propagation delay difference, conductive material of the first conducting structure and/or second conducting structure can be removed 140, so that the first conducting path and the second conducting path is formed, and so that the propagation delay difference is at least partially compensated. The determining 132 of the propagation delay difference from the propagation delays of the first and second signal paths does not necessarily have to be an own step. The step comparing 130 of a propagation delay of a first signal path and a propagation delay of a second signal path can already be the step determining 132 of a propagation delay difference from the propagation delays of the first and second signal paths. This means, for example, that the determining 132 of a propagation delay difference from the propagation delays of the first and second signal paths can be an example of the step comparing 130 a propagation delay of a first signal path and a propagation delay of a second signal path.

(22) Optionally, the method 100 can comprise a shaping 142 of the first conducting structure on the printed circuit board by removal of conductive material such that the first conducting path is obtained therefrom having a first electrical length and a shaping 144 of the second conducting structure on the printed circuit board by removal of conductive material such that the second conducting path is obtained therefrom having a second electrical length, wherein the first electrical length is, for example, shorter than the second electrical length. The shaping steps 142 and 144 don't have to be steps on their own. They can, for example, be details of the step removing 140 of conductive material of the first conducting structure and/or the second conducting structure. Thus, the shaping steps 142 and 144 can define how the removing 140 of conductive material of the first conducting structure and/or of the second conducting structure can be realized.

(23) Optionally, the method 100 can comprise the step removing 146 conductive material of the first conducting structure such that the first conducting path obtained forming a straight line in a defined range of the first conducting path and a removing 148 of conductive material of the second conducting structure such that the second conducting path is obtained forming a non-straight line in a corresponding defined range of the second conducing path. The removing steps 146 and 148 can be examples of the removing 140 of conductive material of the first conducting structure and/or of the second conducting structure. Thus, the removing steps 146 and 148 don't necessarily have to be steps of their own.

(24) In other words, the method 100 can adjust skew of differential pairs for cable assemblies. Wires, for example, the first cable and the second cable, can be soldered to the solder pads (for example, contact pads connected with a conducting structure) of the PCB without upfront measurement of signal propagation time in the wires. Afterwards, the signal propagation times of the single lines can be measured and stored. The design of the traces, for example, the conducting paths, connecting the solder pads and related contact pads can include the possibility of a subsequent adjustment of the trace lengths by removing parts of these structures, so that propagation times within differential pairs may be matched. The partial removing of the, for example, metallic structure of the trace may be done by etching methods, milling/routing, laser ablation or any other method which can eliminate the metallic trace material.

(25) Avoiding upfront measurement of single wires and sorting them means lower manual effort and therefore lower overall costs of the final cable assembly. In addition to that, it could be avoided that wires are mixed up before soldering, which could improve yield and/or quality.

(26) In other words, in an embodiment of the method 100, cable lines are cut to a defined length and on one side a final connector can be applied. The other side can be soldered to a PCB as usually applied for pogo cable assemblies in the pogo block, or for board cables at the board connector side. There is no measurement or sorting necessary before the soldering process. The sub-assembly is, for example, connected to a TDR (time domain reflectometry measurement) and all the lines are, for example, measured for their signal propagation delay subsequently. Based on the measured values, it is possible to adjust the propagation delay of each single line. The adjustment can be made on the PCB, which can be part of the cable sub-assembly.

(27) In other words, the method 100 can be used to adjust the electrical path lengths for cables.

(28) FIG. 2 shows a schematic view of a printed circuit board 200 (PCB) comprising contact pads 210.sub.1 to 210.sub.n for, for example, a mating connector or mating plug and contact pads 212.sub.1 to 212.sub.n, respectively soldering pads, for a cable core (e.g. inner conductor) 222.sub.1, 222.sub.2 (signal), a conducting structure (e.g. trace) 230.sub.1 to 230.sub.n connecting the contact pads 212.sub.1 to 212.sub.n with the contact pads 210.sub.1 to 210.sub.n and an area for ground 240, wherein n can be a natural number.

(29) A first cable 220.sub.1 and a second cable 220.sub.2 can be connected to the PCB by, for example, soldering of the cable core 222.sub.1 and 222.sub.2 to the contact pads 212.sub.1 and 212.sub.2. The first cable 220.sub.1 and the second cable 220.sub.2 can comprise a cable core 222.sub.1, 222.sub.2, an inner dielectric insulator 224.sub.1, 224.sub.2, a conductive shield 226.sub.1, 226.sub.2 and a jacket 228.sub.1, 228.sub.2. The first cable 220.sub.1 and the second cable 220.sub.2 can, for example, represent a differential cable pair.

(30) The invention is based on the idea that wires, for example, the first cable 220.sub.1 and the second cable 220.sub.2, could be just cut with a defined length tolerance and then soldered without upfront measurement and unsorted to the PCB. Then each line can be measured concerning the electrical propagation time from the contact pads 210.sub.1 to 210.sub.n in the front of the PCB to the end of the cable 220.sub.1, 220.sub.2, which is not connected to the PCB. In the conducting structure 230.sub.1 to 230.sub.n between the contact pads 212.sub.1 to 212.sub.n and the contact pads 210.sub.1 to 210.sub.n, it is possible to subsequently adjust the propagation time of each line (for example, from the contact pads 210.sub.1 to 210.sub.n to the end of the cable 220.sub.1, 220.sub.2). The adjustment of the propagation time of each line/connection could be done, for example, after measurement of the pre-assembly (cables/wires plus PCB). By that, also the tolerance on the soldering position of the wire to the PCB 200 would be corrected. Thus, one can save the effort for previous measurements, sorting and correctly sorted soldering. In other words, the invention would avoid the upfront measurement and sorting of the wires.

(31) FIG. 3 shows a schematic view of a printed circuit board 200 comprising contact pads 210.sub.1 to 210.sub.13 to contact, for example, pogo or board connectors, contact pads 212.sub.1 to 212.sub.13, for cable lines (signals), conducing paths 230.sub.1 to 230.sub.13, respectively traces, and a pad 240 to solder ground GND (cable shieldings). Two cables, a first cable 220.sub.1 and a second cable 220.sub.2, can be connected to the PCB 200 by, for example, soldering a cable core 222.sub.1, 222.sub.2 to the contact pad 212.sub.1, 212.sub.2 and by connecting a cable shielding 226.sub.1, 226.sub.2 to the ground pad 240. The first cable 220.sub.1 and the second cable 220.sub.2 can also comprise an inner dielectric insulator 224.sub.1, 224.sub.2 and a jacket 228.sub.1, 228.sub.2. Thus, the first cable 220.sub.1 and/or the second cable 220.sub.2 can be coaxial cables.

(32) The cable core 222.sub.1, 222.sub.2 can be a copper core and the cable shielding 226.sub.1, 226.sub.2 can be a copper shielding.

(33) The propagation delay adjustment according to this invention can take place on the PCB 200 at the conducting path 230.sub.1 to 230.sub.13. For example, for the first cable 220.sub.1 and the second cable 220.sub.2, the signal propagation delay adjustment can take place in the area 250. The adjustment of the signal propagation delay of each line can, for example, be realized by forming the conducting structures 230.sub.1 to 230.sub.13 and thus giving the individual conducting paths 230.sub.1 to 230.sub.13 individual lengths.

(34) Also, only a first cable 220.sub.1 and a second cable 220.sub.2 is connected to a PCB 200 in FIG. 3 and FIG. 2, it is possible to connect on each contact pad (contact pad 212.sub.1 to 212.sub.n in FIG. 2 and contact pads 212.sub.1 to 212.sub.13 in FIG. 3) on the PCB 200 a cable. According to the embodiment of FIG. 3 up to 13 cables all together can be connected to the PCB 200.

(35) FIG. 4 shows a schematic view of a printed circuit board 200 comprising a first contact pad 212.sub.1, configured to contact a first cable 220.sub.1, a second contact pad 212.sub.2, configured to contact a second cable 220.sub.2, a third contact pad 210.sub.1, configured to contact a device 260, a fourth contact pad 210.sub.2, configured to contact a device 260, a first conducting path 230.sub.1, connecting the first contact pad 212.sub.1 with the third contact pad 210.sub.1, and a second conducting path 230.sub.2, connecting the second contact pad 212.sub.2 with the fourth contact pad 210.sub.2. Also, in FIG. 4, it is shown that the third contact pad 210.sub.1 and the fourth contact pad 210.sub.2 are configured to contact the same device 260, it is also possible that each contact pad is configured to contact an individual device.

(36) Conductive material of a conducting structure 232.sub.2 connecting the second contact pad 212.sub.2 and the fourth contact pad 210.sub.2 is removed subsequent to a definition of the conducting structure 232.sub.2 to thereby define a second conducting path 230.sub.2 so that a propagation delay difference of signal paths comprising the first conducting path 230.sub.1 and the second conducting path 230.sub.2 is at least partially compensated. The conducting structure 232.sub.1, 232.sub.2 in FIG. 4 is only schematically and not necessarily has to be a straight line in a rectangular geometry. The conducting structure 232.sub.1, 232.sub.2 can have any shape, like a trapezoidal shape, a hexagonal shape, a circular shape and may include bends or turns.

(37) This means, for example, that for each cable, the first cable 220.sub.1 and the second cable 220.sub.2, a propagation delay can be measured. The first cable 220.sub.1 and the second cable 220.sub.2 can represent a differential cable pair, thus it is desired that the signals propagating through the first cable 220.sub.1 reach the third contact pad 210.sub.1 nearly at the same time with a defined, small tolerance as signals propagating through the second cable 220.sub.2 reach the fourth contact pad 210.sub.2. For example, if the signal propagating through the second cable 220.sub.2 is faster than the signal propagating through the first cable 220.sub.1, the second conducting path 230.sub.2 can be elongated by removing conductive material (e.g. shown by the shaded parts) of the conducting structure (e.g. adjustment area) 232.sub.2 in such a way that, for example, like shown in FIG. 4 a zigzag path is shaped. From the first conducting structure 232.sub.1 conductive material is removed (e.g. shown by the shaded parts), for example, such that the first conducting path forms a straight line between the first contact pad 212.sub.1 and the third contact pad 210.sub.1. As shown in FIG. 4, now the first conducting path 230.sub.1 is a straight line and the second conducting path 230.sub.2 has a part where it is sharp angled. Thus, the second conducting path 230.sub.2 is longer than the first conducting path 230.sub.1 and with this modification the signals propagating through the first cable 220.sub.1 and propagating through the second cable 220.sub.2 can reach the third contact pad 210.sub.1 and the fourth contact pad 210.sub.2 nearly at the same time. Thus, the removal of conductive material of the conducting structure 232 can result in an at least partial compensation of the propagation delay difference of the signal propagating through a first cable 220.sub.1 and the signal propagating through a second cable 220.sub.2.

(38) Thus, the shape of the second conducting path 230.sub.2 on the printed circuit board 200 is electrically elongated by the removal of conductive material compared to the first conducting path 230.sub.1 on the printed circuit board 200 in order to at least partially compensate a propagation delay difference between the first cable 220.sub.1 and the second cable 220.sub.2.

(39) In an embodiment, the first conducting path 230.sub.1 is shaped so that the trace width of the first conducting path 230.sub.1 is constant between the first contact pad 212.sub.1 and the third contact pad 210.sub.1 by subsequent removal of conductive material of a conducting structure 232.sub.1.

(40) Both conducting paths 230.sub.1 and 230.sub.2 have, for example, before a removal of conductive material the similar trace geometry 232.sub.1, 232.sub.2 (e.g. a similar conductive adjustment area). After the removal of conductive material, for example, the first conducting path 230.sub.1 is a straight line with a constant width and the second conducting path 232 is a line with constant width but a zigzag geometry.

(41) In an embodiment, the first conducting path 230.sub.1 and the second conducting path 230.sub.2 can be arranged in parallel to each other, except for an area (for example, the area of the conducting structure 232.sub.1, 232.sub.2) in which the second conducting path 230.sub.2 comprises an elongation created by the removal of conductive material of a conducting structure. In an embodiment, the first conducting path 230.sub.1 and the second conducting path 230.sub.2 can be arranged in parallel to each other, but including an adjustment area in each trace to allow for the propagation delay adjustment. In other words the conducting paths 230.sub.1, 230.sub.2 can be arranged in the complete area (e.g. between the respective pads) parallel to each other. They only comprise the conducting structure (adjustment area), which is configured to control the propagation delay difference (between the first signal path and the second signal path).

(42) According to an embodiment, the first line 270.sub.1 along which the first contact pad 212.sub.1 and the second contact pad 212.sub.2 are aligned, can be parallel to a second line 270.sub.2 along which the third contact pad 210.sub.1 and the fourth contact pad 210.sub.2 are aligned. Thus, the distance between the first contact pad 212.sub.1 and the third contact pad 210.sub.1 is the same as the distance between the second contact pad 212.sub.2 and the fourth contact pad 210.sub.2. Thus a propagation delay of each line (A first line is, for example, the first cable 220.sub.1, the first contact pad 212.sub.1, the first conducting path 230.sub.1 with the first conducting structure 232.sub.1 and the contact pad 210.sub.1. A second line is, for example, the second cable 220.sub.2, the second contact pad 212.sub.2, the conducting path 230.sub.2 with the conducting structure 232.sub.2 and the fourth contact pad 210.sub.2) can be measured under equal conditions, whereby at the measurement, no conductive material is removed from the conducting structures 232.sub.1, 232.sub.2. The shaded parts of the conducting structures 232.sub.1, 232.sub.2 are not modified for a first measurement of the propagation delay. When the propagation delay difference between the two lines is known, conductive material of the conducting structures 232.sub.1, 232.sub.2 can be removed such that the propagation delay difference is at least partially compensated.

(43) In an embodiment, the printed circuit board 200 comprises a connector connected to the third contact pad 210.sub.1 and the fourth contact pad 210.sub.2, wherein the connector is configured to connect to a board. Thus, it is easy to connect the printed circuit board according to the invention with a device 260.

(44) In an embodiment of the printed circuit board 200 one end of the first cable 220.sub.1 which is not connected to the printed circuit board 200 is attached to a connector, and one end of the second cable 220.sub.2 which is not connected to the printed circuit board 200 is attached to a connector.

(45) FIG. 5 shows a section of a printed circuit board comprising a first contact pad 212.sub.1, configured to contact a first cable 220.sub.1, a second contact pad 212.sub.2, configured to contact a second cable 220.sub.2, a third contact pad 210.sub.1, configured to contact a device, a fourth contact pad 210.sub.2, configured to contact a device, a first conductive structure 232.sub.1, configured to form a first conducting path 230.sub.1 connecting the first contact pad 212.sub.1 and the third contact pad 210.sub.1, and a second conductive structure 232.sub.2, configured to form a second conducting path 230.sub.2 connecting the second contact pad 212.sub.2 and the fourth contact pad 210.sub.2. The first conductive structure 232.sub.1 (i.e. a first adjustment area) and the second conductive structure 232.sub.2 (i.e. a second adjustment area) are configured to allow for a modification of the propagation delay. This can be an example of a printed circuit board before any modifications.

(46) According to an embodiment the entire first conductive path 230.sub.1 between pad 210.sub.1 and 212.sub.1 can be designed as the first conductive structure 232.sub.1 (i.e. the adjustment area (A1)), and analogical this is valid for other conductive path's. According to an embodiment of the printed circuit board, the first conducting structure 232.sub.1 and the second conducting structure 232.sub.2 can be arranged in parallel to each other. Thus, it is easier to remove conductive material of the conducting structures 232.sub.1, 232.sub.2 and space on the printed circuit board can be saved and an electrical performance can be improved.

(47) Optionally, a first design reference line 270.sub.1 at which the first contact pad 212.sub.1 and the second contact pad 212.sub.2 are aligned, can be parallel to a second design reference line 270.sub.2 at which the third contact pad 210.sub.1 and the fourth contact pad 210.sub.2 are aligned.

(48) According to an embodiment, the first conducting structure 232.sub.1 contains a conductive area and the second conducting structure 232.sub.2 contains a similar conductive area. The first area and/or second area are intended to allow for a removal of conductive material by laser ablation, milling or etching so that a shape and an electrical length of the first conductive path 230.sub.1 or the second conductive path 230.sub.2 may be defined by the removal.

(49) The first conducting structure 232.sub.1 and/or the second conducting structure 232.sub.2 can have a trapezoidal or hexagonal shape. In FIG. 5, exemplarily, a trapezoidal shape is illustrated.

(50) In the section (e.g. a cutout section) of the printed circuit board of FIG. 5, also a Ground pad 240 is shown.

(51) The first cable 220.sub.1 and the second cable 220.sub.2 can be coaxial cables. Thus, for example, the cable core 222.sub.1, 222.sub.2 can be soldered to the contact pads 212.sub.1, 212.sub.2 and the cable shielding 226.sub.1, 226.sub.2 can be soldered to the ground pad 240. The cable core 222.sub.1, 222.sub.2 can be separated from the cable shielding 226.sub.1, 226.sub.2 by an inner dielectric insulator 224.sub.1, 224.sub.2.

(52) The first conducting path 230.sub.1 and the second conducting path 230.sub.2 can, for example, comprise copper material. These copper traces (for example, the first conducting path 230.sub.1 and/or the second conducting path 230.sub.2) can be prolonged well-defined to achieve, for example a possible propagation time increase.

(53) The details shown in FIG. 5 can, for example, be a section of the printed circuit board 200 shown in FIG. 2.

(54) If a measurement of the complete signal paths comprising the soldered cables 220.sub.1, 220.sub.2 shows that line A is x picoseconds shorter than line B, an elongation can be accomplished by (for example, mechanical) post-processing (for example, milling of the traces, for example of the conducting structures 232.sub.1, 232.sub.2).

(55) This post-processing can be seen in FIG. 6, which shows a detail of the first conducting path 230.sub.1 and the second conducting path 230.sub.2 as, for example, shown in FIG. 5.

(56) As shown in FIG. 6, the black shaded areas 234.sub.1, 234.sub.2 can be removed. Graduations are also possible. According to an embodiment, the black shaded area 234.sub.1 represents a first area of the printed circuit board which is formed by removal of conductive material of a conductive structure 232.sub.1 by laser ablation, milling, routing or etching, which is located closer to a cable-sided edge of the printed circuit board than a second area, represented by the black shaded area 234.sub.2 of the printed circuit board which is formed by removal of conductive material of a conductive structure by laser ablation, milling, routing or etching.

(57) By the removal of the shaded area 234.sub.1 of the conducting structure 232.sub.1, the first conducting path 230.sub.1 is elongated. And with the removal of the shaded area 234.sub.2 of the conducting structure 232.sub.2, the second conducting path 230.sub.2 can be realized geometrically shorter (but electrically nearly equal to) than the first conducting path 230.sub.1. Thus, with this modification, a propagation delay difference between line A and line B of x picoseconds can at least partially be compensated.

(58) The first conducting path 230.sub.1 and the second conducting path 230.sub.2 are arranged in parallel to each other, except for trace sections 238.sub.1, 238.sub.2 by which the first conducting path 230.sub.1 receives an elongation created by the removal of conductive material of the first conductive adjustment area 232.sub.1. Similar trace sections 238.sub.1, 238.sub.2 as shown for the first conducting path 230.sub.1, can be realized for the second conducting path 230.sub.2. The decision, which path 230.sub.1 or 230.sub.2 receives the elongation trace sections 238.sub.1, 238.sub.2 depends, for example, on which path 230.sub.1, 230.sub.2 has to be elongated to compensate at least partially a propagation delay difference between line A and line B.

(59) The FIG. 7a, FIG. 7b and FIG. 7c can, for example, show an illustration of three steps of a method for providing two electrical connections with a very small propagation delay difference between them as a differential pair.

(60) FIG. 7a shows a schematic view of a printed circuit board 200, which can comprise the same attributes with same functionalities as shown in FIG. 5. Within the area 250, the PCB-traces (for example, the first conducting path 230.sub.1, and the second conducting path 230.sub.2) have sections with a larger width (for example, in the conducting structure 232.sub.1 and the second conducting structure 232.sub.2) in order to reach a signal propagation delay increase, if needed.

(61) With the printed circuit board 200 plus assembled cables as shown in FIG. 7a, a TDR measurement can be executed, to measure propagation delays of line A and line B.

(62) Line A comprises the third contact pad 210.sub.1, the conducting path 230.sub.1, the conducting structure 232.sub.1, the first contact pad 212.sub.1 and the first cable 220.sub.1. Line B comprises, for example, the fourth contact pad 210.sub.2, the second conducting path 230.sub.2, the conducting structure 232.sub.2, the second contact pad 212.sub.2 and the second cable 220.sub.2.

(63) If the TDR measurement shows that line A is electrically shorter than line B, line A can, for example, made longer. This can be done by removing the marked area 234.sub.1 in the signal path A. Physically this may be reached by milling, laser ablation or a defined etching process. The increased line width 234.sub.2 (i.e. an enlargement) of line B may also be removed. According to an embodiment, the marked area 234.sub.1 represents a first area of the printed circuit board which is formed by removal of conductive material of a conductive structure 232.sub.1 by laser ablation, milling, routing or etching, which is located closer to a cable-sided edge of the printed circuit board than a second area, represented by the increased line width 234.sub.2 of the printed circuit board which is formed by removal of conductive material of a conductive structure by laser ablation, milling, routing or etching.

(64) FIG. 7b can show the same attributes and functionalities as shown in FIG. 7a.

(65) FIG. 7c can also show a printed circuit board 200 with the same attributes and functionalities as the printed circuit board 200 shown in FIG. 7b or FIG. 7a.

(66) FIG. 7c shows the printed circuit board 200, for example, after the modification. As a result, the lines may be matched with a very low propagation delay difference.

(67) As shown in FIG. 7c, the first conducting path 230.sub.1, comprises a trapezoidal portion so that the first conducting path 230.sub.1 is electrically elongated compared to the corresponding second, straight conducting path 230.sub.2.

(68) The herein described invention has the advantages that the cables 220.sub.1, 220.sub.2 do not need to be measured and sorted before the assembly step (avoids mix-ups). Also, the measurement of the lines can be made in the cable assembly state of production and the post processing (milling step) may be automated.

(69) FIG. 8 shows a printed circuit board according to an embodiment of the invention, which can comprise the same features and functionalities as the printed circuit board 200 shown in FIG. 7a, FIG. 7b and FIG. 7c. As shown in FIG. 8, the area 234.sub.1 of the conducting structure 232.sub.1 can have smaller increments. Thus, only a small space is needed by the first conducting path 230.sub.1.

(70) The FIGS. 9a, 9b, 9c, 9d and 9e show a conducting path 230 with a conducting structure 232 according to an embodiment of the invention. The conductive structure 232 can be configured to allow for a modification of the propagation delay by definition of shapes of the conducting path 230. Conductive material as marked by the shaded area 234 can be removed of the conducting structure 232, in order to modify the electrical length of the conducting structure 232, to obtain a conducting path 230.

(71) The conducting path 230 can thus comprise an area 232, where it is, for example, sharp angled (see FIG. 9a), trapezoidal (see FIG. 9b), hexagonal (see FIG. 9c), rippled (see FIG. 9d) or circular (see FIG. 9e). This list of shapes of the conducting path 230 is to be regarded as exemplarily and not as exhaustive.

(72) Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or device corresponds to a method step or a feature of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or item or feature of a corresponding apparatus.

(73) The above described embodiments are merely illustrative for the principles of the present invention. It is understood that modifications and variations of the arrangements and the details described herein will be apparent to others skilled in the art. It is the intent, therefore, to be limited only by the scope of the impending patent claims and not by the specific details presented by way of description and explanation of the embodiments herein.