Method of high-frequency tuning an electrical device and a printed circuit board therefor

METHOD OF HIGH-FREQUENCY TUNING AN ELECTRICAL DEVICE, AND A PRINTED CIRCUIT BOARD THEREFOR

02072/0003.000

Method for RF matching of an electrical arrangement, as well as a printed circuit board which is suitable for this purpose

The invention relates to :a method , for RF matching of an electrical arrangement, and to a printed circuit board which is suitable for this purpose.

EP 0 525 703 Al discloses a plug connection for 10 computer networks in the domestic area, comprising a male connector part and a female connector part, with a device for crosstalk compensation being arranged in.the plug connection, by means of which the crosstalk attenuation between the transmission conductor, loop and.

the reception conductor loop can be increased. For this., purpose, a printed circuit board is arranged in the female connector part or in the male connector part of the plug connection between the connections for the plug-in cable and the connections for the wiring, with 20 the conductor routes for the transmission and reception conductor loops being largely physically separated on the printed circuit board. The devices for crosstalk compensation are, for example, discrete components such as capacitors or coils, which are adjustable. The known 25 plug connection has the disadvantage that the discrete components are relatively expensive and large.

DE 100 51 097 Al discloses an electrical plug connector comprising a plug connector housing, a printed circuit 30 board with two sets of contact elements, with the first set of contact elements being arranged on the front face of the printed circuit board and projecting into an opening in the plug connector housing, and the second set of contact elements being arranged :on the 35 rear face of the printed circuit board, and the contact elements in the second set being in the form of insulation-displacement 1 contacts, with the plug

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connector having a cable manager which has an opening through it and is provided on the front face with . guides for conductors ,which are , intended to make contact with the insulation-displacement contacts, with 5 the . guides being formed in the area of the insulationdisplacement contacts with recessed holders for the insulation-displacement contacts, and in which.case the cable , manager can be matched to the' plug connector ' housing. . .י

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Owing to the increasing bandwidth for data transmission in telecommunications and information technology, the conductors, contacts and conductor tracks have to be designed such that they are highly defined with respect 15 to one another, in order to comply with the required values for the crosstalk.attenuation.

This necessitates extremely tight, tolerances, which can be complied with only with difficulty during automated manufacturing processes. . 20

The invention is thus based on the technical problem of providing a method for matching an RF plug connector, in particular an RJ-45 female connector, having at least one printed circuit board, with the printed 25 circuit board having contact points for RF contacts and contact points for :the insulation-displacement contacts, and with one; contact point for the RF contacts in each case being connected . to a respective contact point for the insulation-displacement contacts, 30 and a printed circuit board which is suitable for this purpose and by means of ׳which the RF characteristics can be adjusted.within a narrow . tolerance band.

The: technical problem is solved by the subject matters 35 .with the features of. patent .claims 1 and 11. .Further advantageous'refinements of the invention are described in the dependent claims.

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.. For this purpose, ..at-. least one . first. conductor track, which is connected on only one side to. a contact point . ' . of an electrical contact, is arranged on. the printed . circuit board and, together with, at׳ least one second 5 conductor track which is: arranged on or in. the printed circuit, board, forms , a ' capacitor,. with. . at least one frequency-dependent parameter of the arrangement being measured, the frequency-dependent parameter being compared with a nominal parameter, and the conductor 10־ track- with which contact is . made on one side being partially removed or cut through as a .function of the difference. This makes it possible to form a matchable capacitor using simple and cost-effective means, and by means of which the. RF response of the arrangement can 15 be matched. . The conductor tracks are in this case preferably connected to 'the contact points of the RF contacts, ' since ׳ this means that the matching capacitances are closer to the location of the source of the crosstalk. However, in principle, they may also 20 be connected to the contact points of the insulation displacement contacts, which are electrically connected to the contact points ofthe RF contacts. It should be noted that, in. principle, it is sufficient to . cut through or to remove one conductor track of a capacitor 25 in order .to change the capacitance. '

The opposite electrode of the capacitor is preferably likewise formed by a conductor track that is connected to a contact point on one side.

In a further preferred'embodiment, at least. one further second conductor track is¹ arranged in an internal layer in the printed' circuit board and is electrically connected to the conductor track on the printed circuit 35 board. This. represents.' capacitances . connected in parallel, so that the total, capacitance is added, thus allowing the formation. of a sufficiently large capacitance on a relatively small, area.

׳.'. , .^Λ . Μ- λ .;. In a further preferred embodiment, at least' two independent capacitors .which, are formed by. conductor . tracks are arranged on the printed circuit board, in . .:. order to' carry out' symmetrical trimming. with respect to

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In a further preferred' embodiment, the frequencydependent parameter is determined and adjusted on the unpopulated printed circuit board. This is. based on the 10 knowledge that,, particularly in the case of RF plug connectors, . the printed circuit board.' itself . is responsible for the majority of the RF tolerances. :׳ '. These tolerances are generally geometric tolerances of the. layout.' . elements, ׳.such as conductor tracks, and 15׳ tolerances of .'.the. dielectric constant of the material' '.of the printed circuit' board. Automatic measurement on. :. an ' unpopulated printed circuit, board is considerably.

easier than on . a populated printed circuit board, or even on a printed circuit board that has been.installed 20 in a housing. The overall arrangement, can thus be matched even at an . early stage in the process of producing . the printed circuit board. The feed and measurement are in this case preferably provided, centrally.in soldered eyes of. the contact points .

25. ' ’ ' :'^:Y. ׳Ί / , . In a further preferred embodiment, only a portion, of.

the estimated, conductor, track shortening ׳.that is necessary is carried . out.. in a ' first step. The frequency-dependent parameter is then measured once 30 again. The measured change is then used to determine the remaining conductor track length that is still to be removed or to be cut. This also takes account, of the tolerances, relating to the׳ conductor tracks in the.

,matching process. Theconductor track shortening .can in 35 this.case also be subdivided into more than two steps.

. In a further preferred embodiment, the final cut during the catting of . the conductor'track is carried out in a broader manner than the first '.cut. This broader cut׳ ^: ,? V.'''..־,⁵.־,!.'.:־'.'' '.A..

minimizes the capacitive influence of. the cut part of the conductor track. ...;...־ .־־ ' ’ ^;

In a further preferred embodiment,, - the near crosstalk :5.-.- is determined as the frequency-dependent parameter, thus making the matching ' process easier,, since, the parameter to be optimized directly is determined,, so ׳ that there is no need for any further estimates of_; the influence of the . parameter on the near crosstalk as 10 would be the case, ..for example, with pure - capacitance.

measurement. '

The conductor track is ׳ !preferably cut by ׳ means of a.laser, preferably by means of a- short-wave laser .with a .15. wavelength that is shorter than' .600 nm. The use of a. laser , for cutting ' the conductor track is extremely fast, and can easily be¹ automated. In principle, the conductor track can also be cut . or ׳ removed mechanically, for example .by means of milling or 20 ׳ electrically ! by using an overcurrent, to burn through it. . .

In a further -preferred embodiment,, the laser has an • . . associated .optical- positioning system. This results in.

25. the conductor track being cut,in a more defined manner, without any.damage to closely adjacent conductor tracks .,.-. and without the conductor track to-be cut not being cut completely.

. During removaljor cutting: of the conductor track, it is possible for copper particles . to be deposited on the I׳ printed circuit board; and ' these in. turn reduce the , resistance to overvoltages. The cutting or removal of the conductor, track, is thus preferably followed by a 35 . cleaning step to remove the copper particles, and/or any other .contamination.

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The invention will be .explained׳ in more, ׳.detail in the.י following text.' with:' ref erence.'. to a pref erred exemplary embodiment. In the figure.:

Figure 1 shows an exploded illustration of a plug׳ connector for transmitting RF data .(.prior . art) , ׳ '

Figure 2 shows, a printed circuit board_: for use in a 10 . plug connector shown in Figure 1, ' Figure 3 shows a : schematic equivalent circuit for.- the . printed circuit board,

Figure. 4 . shows a schematic frequency response for the .'. near crosstalk and

Figure5 ׳ shows a family of curves for the attenuation . . D of the near crosstalk as. a function of the 20 ' length of the conductor track to be removed.

Figure 1. shows an: exploded illustration of a. plug connector 1. The plug^: connector.1 has a plug connector housing .2, a' printed circuit .board 3, . a hold-down 2.5 device 4 and a cable, manager. 5. .The plug, connector housing 2 :in the illustrated example is in the form of a female connector .housing with various latching and insertion means. The plug connector housing 2 has a shielding plate 6 on the side surfaces. The printed .30. circuit board 3 is fitt'ed on its front face with a first set of contacts 7, and is fitted on its rear face with a second , set of insulation-displacement contacts 8. One contact 7 in the first , set is connected to a respective contact 8 in the', second set. The printed 35 circuit board. 3 is then inserted . into the ׳ plug .׳connector housing 2. In the ^process, cylindrical pins 9 of the plug connector housing 2 pass through holes in. the. printed, circuit board 3, so that, the plug connector .housing 2 and the printed circuit board . 3 are adjusted ' : . ' . .'.'. .. ' '.. ' | '. . . .'. . .. ' . .

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and fixed with' respect to one another. The contacts 7 (which are׳ in the form of RF contacts) in the first set then project into an opening, which is accessible׳ from . the front face, of^: the plug connector housing. The hold. 5 down device 4 is. then pushed over the contacts 8in the ^:׳ . U second set, and is latched to' the plug 'connector ' ' housing 2. For . this purpose, the hold-down device 4 has latching tabs .10׳ on . the. end . face, . and has openings 11 . through it for the insulation-displacement contacts: 8.

Furthermore, the hold-down., device 4 has two latching hooks. 12, which are .used for. latching to the cable managers.

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. Figure 2 shows the'unpopulated printed circuit board 3.

The printed circuit board 3 has eight contact points ' 21- 28. and .contact holes for the. RF contacts, and eight contact . points 31-38 for the. insulation' displacement contacts. The printed circuit board .3 also has. further plated-through holes 40 for. connection of 20 conductor tracks on the. front' face . and rear face and internal layers in the printed circuit.board, with the : plated-through . holes . 40 being, illustrated. as small circles. The. holes 41 in the. printed circuit board 3 are in this case illustrated as small squares. The 25 conductor tracks which connect the contact' points 21 - to their respectively !associated contact point 31 38 are not shown, with the exception of two parts of the. contact points 24 and 35 since they are arranged on the rear face and/in'the internal layers :of the printed circuit, board. . In. addition . to the electrically connected conductor .tracks between two contact points 21 - 28 and 31 - 38, respectively, there are also four conductor .tracks .43 - 46. which. are . respectively connected on one side to¹ a contact point .23. - 26. In 35 . ..this case, the two conductor tracks 44 and 46. form a . '. capacitor between, the. contact points 24 and 26. In a corresponding way, the two conductor tracks 43 and.45 ׳ form 'a capacitor 'between 'the contact points 23'. and 25. . ,A . further conductor track . is preferably arranged in . an : ־? י ' ל ' י ,׳ θ - ' .'.'י ' ' internal layer, is electrically connected to׳ conductor track .44,. and islocated under the conductor track 46.

' For circuitry , purposes,. the contact points 21., .22.; 23,

26; 24,. 25 and 27, 28 and’ their respectively associated contacts form a contact 'pair׳. In' this case, . the two outer contact pairs. 21, 22 and 27, 28 are relatively '.uncritical with .regard tonear crosstalk. The two inner and interleaved contact pairs 23, 26 and 24, 25, on the ' other . hand, are problematic. . The capacitances which 10 cause disturbances in this case are. located between 23 and 24 . as well, as between 25 and' 26, since the other couplings are negligible., .owing to the greater distances between them.,

Figure 3 shows the resultant equivalent circuit, including the schematic test layout. In this case, the . capacitors C₄₆ and C35 essentially represent capacitors :formed by. the . conductor tracks' 44 and 46 as well as 43 and 45, respectively, ' while, in contrast,, the 20 capacitors C₃₄ and. C₅₆, respectively, are formed by the adjacent- contact . points .23, 33׳ as well as the associated conductor track, 24, 3.4 with the. conductor track as well as. 25, 35 with the conductor track, and 26., . 36 with the conductor track. This bridge circuit. 25 can now be trimmed in. order to force the near crosstalk below the required values,. Before the trimming, process, the asymmetry is first of all determined by determining the near crosstalk of ,one contact pair as. a frequencydependent parameter. :In the present case, crosstalk is 30 י determined between the contact pair 23, . 33 and 26, 36 .'. and the contact pair 24, .34; 25., 35. Since . the measurement is . preferably carried . out on the unpopulated printed circuit board 3, the contact points 33 .-. 36 are terminated with the correct impedance. The ׳. 35׳ near crosstalk to the contact points, 25, 24 is .then measured, with RF signals being injected ״ into, the . contact .'points 23, .26, by means of. a network analyzer . which is. symbolized in Figure 3 by the .frequency - generator 50. and the measurement device 51. The feeding ./ ?.1 ל/ y \ ־ 9 .-:/ י/. ' . . . .

and measurement of the ;RE signals are' ' in this. 'case, provided by means, of . a central, contact in the solder, eyes of the contact points 23-26.

Figure 4 schematically shows the. frequency .response of. .. ' the. ' .near crosstalk '. NEXT, with the . profile a .. representing nominal near crosstalk, . and. the .profile b representing .the. measured actual near crosstalk., for a measured, printed, circuit ' board.: The nominal.. near 10 crosstalk is . determined, for. example, by means of a

I golden device. In this case, the measured, near.' ־:׳' 'crosstalk, is׳ too., high by an amount Z NEXT, so. that this, must be compensated . for. by shortening the conductor tracks, thus reducing the capacitance. The measure of ^:15 how many millimeters of conductor track correspond to .'what' capacitance and thus to the near crosstalk attenuation-D depends on the tolerances of' the printed . . circuit. board, ' such as the dielectric ::constant or the distance between., the conductor . tracks. . .There. . is 20. therefore no single straight line,but an entire family of curves, as is illustrated schematically in Figure 5. Since the tolerances are ; unknown,. it may first of all be necessary, to determine' which curve is applicable to the printed circuit board to be matched. For. this 25 . purpose,, a piece of conductor track is first of .all . removed or cut through, and the measurements are then carried out׳ once again. The increase in. the attenuation D that is found can. then be. used to determine .the associated. curve. If, on’ the other hand, the desired 30 attenuation is greater than that.which can.be achieved with' the steepest curve, . the entire conductor track can . be removed or cut through without any intermediate step. The method is then . repeated־, on the '.other capacitor. .'. . '

'. ' . ' ׳ ׳ .35

The conductor track is preferably cut through by means ; of a short-wave laser, whose power' and. focusing, are matched to the copper track to be cut such that, as far '. as possible, this is all that is.removed. The advantage.

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of a laser is its, high . speed with good reproducibility, so that the matching process can .easily be automated.

. . >.. - 11 .List of reference symbols

1) Plug '.connector:.' :,׳.!.'.

2) Plug connector housing

3) Printed circuit, board

4) Hold-down. device'

5) Cable manager.:

6) Shielding plateΐ

7) Contacts

). .' Contacts .

.9) Cylindrical pins . J

<td></td><td> 10)</td><td> Latching</td><td> tabs .</td><td></td><td></td>

<td></td><td> 11k.</td><td> Openings</td><td></td><td></td><td></td>

<td> 15'</td><td> : 12)</td><td colspan="2"> Latching hook</td><td></td><td></td>

<td></td><td> 21)</td><td> Contact</td><td> points</td><td> (for RF</td><td> contacts): .</td>

<td></td><td> 22)</td><td> Contact</td><td> points</td><td> .(for RF</td><td> contacts)</td>

<td></td><td> 23)</td><td> Contact</td><td> points</td><td> (for.RF</td><td> contacts)</td>

<td></td><td> 24)</td><td> Contact</td><td> points</td><td> (for. RF</td><td> contacts)</td>

<td> 20</td><td> 25)</td><td> Contact .</td><td> points</td><td> (for RF</td><td> contacts) ׳ .</td>

<td></td><td> 26).</td><td> Contact</td><td> points .</td><td> (for. RF</td><td> contacts).</td>

<td></td><td> 27)</td><td> . Contact</td><td> points</td><td> (for RF</td><td> contacts)</td>

<td></td><td> 28) .</td><td> Contact</td><td> points</td><td> (for RF</td><td> contacts)</td>

<td></td><td>³¹)</td><td> Contact</td><td> .point</td><td> (for</td><td> an insulation-displacement</td>

<td> .25.-</td><td></td><td> contact)</td><td></td><td></td><td></td>

<td></td><td> : 32) .</td><td> Contact'</td><td> point</td><td> (for </td><td> an insulation-displacement</td>

<td></td><td></td><td> contact.)</td><td></td><td></td><td></td>

<td></td><td> 33) '</td><td> . Contact</td><td> point</td><td> (for</td><td> an insulation-displacement</td>

<td></td><td></td><td> contact)</td><td></td><td></td><td></td>

<td> 30</td><td> 34)</td><td> Contact</td><td> point</td><td> (for</td><td> an insulation-displacement</td>

<td></td><td></td><td> contact)</td><td></td><td></td><td></td>

<td></td><td> 35) .</td><td> Contact</td><td> point'</td><td> (for</td><td> an insulation-displacement</td>

<td></td><td></td><td> contact)</td><td></td><td></td><td></td>

<td></td><td> 36)</td><td> . Contact</td><td> point</td><td> (for</td><td> an insulation-displacement</td>

<td> 35</td><td> . 37)</td><td> , contact) Contact contact)</td><td> point</td><td> (for</td><td> an insulation-displacement</td>

<td></td><td> ' 38)</td><td> .:Contact</td><td> point</td><td> (for</td><td> an insulation-displacement</td>

contact) י . T.12:

'. . 40 ) Plated-through hole _: ..

41) ' Hole i.1.' Ο ׳'[ ' '

3. ) Conductor track׳ ׳ :

• 44) Conductor׳ track ).

4.5 ׳) . Conductor track . 1 ;׳

46) Conductor track

50) Frequency generator ׳

51) Measurement device >.

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WO 2004/082343 : 13 ד “ . PCT/3P2004/qp1952 ך

Patent .claims יי . י י . >

1,. A method for RF matching of an RF plug connector (1), having a .printed :circuit. board (3.), with the. .

printed circuit board having contact points (21-28) for RF contacts ': and.' contact points (31-38) for . insulation-displacement contacts, with one .. contact point (21-28) for the RF contacts in each case being connected to a respective contact point (3138־) for the

1.,0 insulation-displacement contacts, and. with, capacitive , coupling, which causes Inear-end crosstalk, occurring. between the RF contacts, ׳. characterized in that ;

. at least one . first conductor track . (46) , which, is 15 connected on only one side' to a contact point (26) of an electrical contact, is arranged on the printed circuit board (3) and,: together with at least one ' second conductor track (44) which is arranged .on and/or in the printed circuit : board (3) , forms a capacitor 20 (C₄₆) , with at least, one frequency-dependent parameter of the arrangement being measured, the frequency-, dependent parameter : being compared with a nominal ' parameter, and the 'conductor track (46) with, which contact is made on one side being partially removed or .

cut through as a function of the difference.

2. The method as claimed in claim 1, characterized in that the second conductor track (44) is in the form of a conductor track (44) with which contact is made on

0 one side. . :.

3. The method as claimed in claim. 1 or 2, characterized in that at leastone further. second conductor track is arranged. in an internal layer in the

5 printed circuit board (3) and is: connected to the second conductor track' (44) that is arranged on the printed circuit board (3).

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4. The׳ method, as claimed in. one of ׳ .the. preceding . .claims, characterized in .that, at least two matchable ־. capacitors (C.-;₆, C₃₅) are arranged :on .the printed circuit board (3) . ־ .../ : 5. ⁶‘Λ ⁷1 : '/? .. / 1 . 1//:׳ . 5. The method as . claimed, in one of the . preceding. . .׳.claims, characterized in that the frequency-dependent parameters are : determined on the unpopulated' printed .-. circuit board (3),.

/״ ./ ׳ ^: 6. ^: The method as claimed in one of the preceding׳ . .claims, Characterized in that in a first step, only a . . portion of the .estimated conductor track shortening (L) . that is necessary is carried out, the frequency15 dependent parameter is measured once again, and the.

׳׳.. remaining .'conductor' track,. length . which ׳ is still to. .be; removed or to be cut is determined from this.

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7. The method as claimed in claim 6, characterized in 20 . that, in the final step, ; the conductor track . (46, 45)

..is cut in a broader manner, than in the first step.

8. The method as . claimed in one of the preceding claims, characterized in [that near crosstalk (NEXT) is determined as the frequency-dependent parameter.

9. The method as claimed in one of the preceding claims, characterized in that the conductor track (46, 45) is cut.by means of a laser.

. . / / '׳ 0 3

10. The method as claimed in one of the preceding claims,. characterized in that .the process. of. controlling the laser is assisted by means of״, an optical system. . . . ־ ' , ׳' ׳ ' ' . &lt;

11. A printed circuit, board for . holding RF .contacts . and- insulation-displacement contacts for an RF׳ plug .connector, with the. printed circuit board having eight contact points (21-28) for RF .contacts and eight י . γ. . ' ;.. . ־ ־ י י.' י / .' .. . י . י : ' . ^; .י' י

״.״'X ׳. .׳ . - י.? .. . X. ^: ' .׳׳. . X . .' י.׳ ׳contact' points (31-38) : for insulation-displacement contacts, with one contact.' point (21.-28) 'for the RF contacts in each case being connected to a. respective ' contact point (31-38) for the. insulation-displacement 5 contacts, and with capacitive coupling . which causes ׳.; near.-end crosstalk occurring between the RF contacts, .

characterized in that at least, one first conductor track (46), which is connected on only one. side to. a' contact point (.2 6) of .10 an electrical contact, is .arranged on the printed circuit board (3) and,־ together with at . least, one second conductor track (44) which is arranged on and/or in the printed, circuit board' (3)-, forms a capacitor.

. (C₄₆) . . : . 'X /- :. : ׳' X lx ’ _; -.:. .׳:׳ x''x;'. ׳ X'. ׳. ר'.

12. . The printed circuit 'board as claimed in claim 11, .. characterized in that the second conductor track (44) is likewise a^: conductor track (44) .which is connected . to a contact point (24) on one side.

. 20 . . ' '

13. The printed circuit_:board as claimed in. claim 11 or 12, characterized in that at least one further second conductor .track is; arranged in an internal layer in the. printed . circuit, board (3) . and. is connected to the. further' conductor . track (44) .that is. arranged on .. the printed circuit board (3).

<td rowspan="2"> 30.</td><td colspan="2"> 14,. The printed circuit! board as claims 11 to 13, characterized, in</td><td colspan="2"> claimed ' in one that at least</td><td rowspan="2"> of two the</td>

<td> matchable ׳. capacitors (C46, C₃₅) printed circuit board (3).</td><td> are</td><td> arranged</td><td> on</td>

<td></td><td> 15; The printed circuit: board</td><td> as</td><td> claimed in.</td><td> one</td><td> of</td>

claims 11 to 14;. characterized, in that the first .3.5' capacitor (C46) . is arranged between the contact points (24. and 26) , and' the second .capacitor (C₃₅) is arranged ' י י between the contact points (23 and 25). ..

. The method according! to any one of claims' 1-10, substantially as herein described with reference to the description and drawings. ; . : '

17. The method substantially as herein described with reference to the description and . drawings .

18. The printed circuit according to any one of claims 11-15, substantially as herein described with reference to the description and drawings.

19. The printed circuit substantially as herein described with reference to the description and drawings.