DE10336290A1 - Circuit board for highest clocking frequencies, which includes a supply layer, also has damping structure attenuating waves more strongly at edges than in center - Google Patents

Abstract

The electrically-conducting layer (600) supplying components on the board with a potential, has central- (100) and edge- (102) regions. A damping structure with a resistance is coupled with these regions, such that a wave propagating along the layer (600) is more strongly damped at the edge region than in the central region of the layer (600). A further conductive layer (406) separated from the layer (600) by dielectric, supplies components with a different potential.

Description

The The present invention relates to a circuit board having a Supply situation and in particular a circuit board with a Supply situation which improved with respect to a damping of high-frequency interference Features.

at The development of electronic circuits often arises Problem, the power supplies of various building blocks of a system on a board so that ensures a secure function is. This becomes more difficult the higher the clock frequencies of the digital circuit parts are. Extreme demands are being made the supply made faster CMOS circuits. Due to the high clock frequencies must level change signals are made very quickly. Because the load capacities mostly are predetermined, the pulse-shaped current peaks of the supply very high and at the same time broadband. At the same time, these should Current peaks have no influence surrounding circuit parts or systems have. So it has to be on it Care should be taken to ensure that the emissions are as much as possible stay low.

Most of time is the supply voltage of digital circuits through capacities between blocked the positive and negative supply rail. This works very good for circuits with clock frequencies of a few MHz. by virtue of the parasitic inductance these capacities, which is mainly determined by the design, are included in this method high clock rates and steep signal edges set limits.

When A way out is to look at the supply levels within a circuit board only with a very thin one Dielectric (<100 μm) from each other to isolate. This creates a very broadband and low impedance Waveguide system that is very good for supplying fast circuits suitable is.

Indeed this system has the disadvantage that the waveguide spatially limited is and therefore for Waveguide typical λ / 2 resonance phenomena having.

In the publication DE 198 54 271 A1 (see also 6 ) a solution is shown that eliminates these resonances. For this purpose, one or more supply layers 600 divided into honeycomb and the spaces between 602 For example, filled with carbon paste, which has a much higher resistivity than the surrounding copper, from which the supply layer normally consists. In this way, resonance phenomena are eliminated by damping.

The basic idea of the publication DE 198 54 271 A1 Known approach is that the two supply layers with thin dielectric form a waveguide with low characteristic impedance (<1 Ω), which already contains an ohmic resistance coating. As a result, the waveguide itself is no longer resonant, since the wave energy is converted into heat in the waveguide.

adversely However, this approach is also the ohmic resistance the supply is increased at low frequencies. This is an undesirable Effect, since the DC component of the supply current partly several Amperes is. As a consequence, a significant difference arises directly on the component itself lower supply voltage than without damped supply. This endangers the reliable Operation of the circuit. Also falls through such attenuation of resonance phenomena a significantly increased power dissipation already in the supply itself, with an increased waste heat is dissipate.

outgoing from this prior art, the present invention is the Task based, a well steamed and still low-impedance supply system at high frequencies to disposal to put without simultaneously the resistance at low frequencies or increase DC and without the noise emission levels of the supply system.

These The object is achieved by a circuit board according to claim 1.

The present invention provides a circuit board having the following features:
an electrically conductive layer, which can be acted upon to supply components to be arranged on the circuit board with an electrical potential, wherein the layer has a central region and an edge region; and
a damping structure having a resistance coupled to the edge region of the layer such that a wave propagating along the layer is attenuated more than at the central region of the layer due to the resistance of the damping structure at the edge region of the layer.

According to the invention, the approach described above is left to completely provide the waveguide with an ohmic resistance coating and thus to make the waveguide non-resonant. According to the waveguide itself is left unattenuated, while possible Resonan zen be attenuated by a corresponding conclusion at the ends of the waveguide. The wave energy is thus converted into heat only at the edge of the waveguide.

These The approach has the advantage that the supply currents at low frequencies or DC as little resistance is opposed, as in a conventional, undamped supply situation. simultaneously resonances are due to the waveguide properties at the edge region of the supply layers of the supply system (in particular by the damping structure) significantly reduced. This ensures that the supply impedance is also at Frequencies remain low at which massive resonance peaks would occur in the undamped case. In addition, will the disturbance radiation the board significantly reduced.

preferred embodiments The present invention will be described below with reference to the accompanying Drawings closer explained. Show it:

1 a supply layer according to a first preferred embodiment of the circuit board according to the invention in plan view;

2A a supply layer according to a second preferred embodiment of the circuit board according to the invention in plan view;

2 B an edge region of the supply layer according to the second preferred embodiment of the circuit board according to the invention in cross-sectional view;

3 a supply layer according to a third preferred embodiment of the circuit board according to the invention in plan view;

4 a supply system with two supply layers according to a third preferred embodiment of the circuit board according to the invention in cross-sectional view;

5 a supply system with two supply layers according to a fifth preferred Ausführungsbei game of the circuit board according to the invention in cross-sectional view; and

6 a supply layer of a circuit board according to the prior art in plan view.

In the following description of the preferred embodiments of the present invention are for those in the various Drawings shown and similar acting elements the same reference numerals used.

1 shows a supply layer of the circuit board according to the invention, wherein the supply layer preferably by a metal layer 600 (For example, copper) is formed and a central region 100 and a border area 102 having. The metal layer 600 is in the middle range 100 continuous. At the edge 102 has the metal layer 600 interruptions 602 on, so in the edge area 102 the metal layer 600 through the interruptions 602 honeycomb structured. Furthermore, the circuit board according to the invention has a damping structure in the form of conductive material 104 (For example, carbon paste), wherein the conductive material 104 in the breaks 602 is arranged and has a resistance which is higher than a resistance of the metal layer 600 , The extent of the border area 102 the supply situation 600 according to the first preferred embodiment, the central area 100 the supply situation 600 surrounds extends from an imaginary edge of the uninterrupted metal layer 600 by a predetermined distance 106 that is less than 10% of a total dimension 108 the metal layer 600 (For example, between 3 and 5 mm) in the direction of the predetermined route 106 includes. In addition to the in 1 shown honeycomb structure using hexagonal polygons can be the honeycomb structure of the edge region 102 the metal layer 600 also realize by a structure using further polygons, wherein the polygons comprise at least three corners. The metal surface 600 (eg copper surfaces) inside (ie in the middle area 100 ) of the supply situation remain unchanged.

Through such a structured metal layer 600 can a supply situation be realized, that in the middle range 100 a continuous metal layer 600 and thus comprises a low-resistance region for the supply of components to be arranged on the circuit board. The high-frequency level fluctuations (wave) caused by high-frequency switching operations of components to be arranged on the circuit board propagate along the central area 100 the metal layer 600 out. These level fluctuations reach the edge area 102 the metal layer 600 , they are due to the increased wave resistance (ie the increased resistance coating) as well as dissipative shares in the edge area 102 the metal layer 600 more subdued than in the middle range 100 the metal layer 600 , causing a reflection of the wave on one side edge 110 the circuit board is suppressed or at least significantly attenuated. By the border area 102 the metal layer 600 Thus, first, it is ensured that the shaft caused by switching operations in the edge region 102 the supply situation 600 and at the same time the emission of disturbances from the supply situation 600 over the edge area 102 the metal layer 600 or the side edge 110 the circuit board is significantly reduced.

2A shows the supply situation 600 according to a second preferred embodiment of the circuit board according to the invention in plan view. The supply situation is again a metal layer 600 on a substrate that has a central area 100 and a border area 102 includes. At the edge 102 has the metal layer 600 again interruptions 602 which, according to the second preferred embodiment, continuously around the center area 100 are arranged. The interruptions 602 are back with a conductive material 104 (For example, carbon paste) filled, which has a higher resistance than the resistance of the metal layer 600 , Through the interruptions 602 and the conductive material filled therein 104 are the individual frame elements 198 separated from each other.

2 B shows the border area 102 and a portion of the mid-range 100 of in 2A shown second preferred embodiment on a side edge 110 the circuit board in an enlarged cross-sectional view. Here is the metal layer 600 on a substrate 200 arranged, wherein the metal layer 600 in the middle area 100 is continuous while the metal layer 600 at the edge 102 interruptions 602 having, with the conductive material 104 are filled. Through the interruptions 602 and the conductive material filled therein 104 are the individual frame elements 198 separated from each other.

By the in 2A and 2 B illustrated and relatively easy to produce frame elements 198 of one or more frames around the central area 100 the metal layer 600 Again, it is possible to have one in the middle section 100 caused wave in the edge area 102 to dampen. The functioning of the in the 2A and 2 B shown frame structure as a damping structure corresponds to the above in 1 described damper structure in honeycomb shape and will not be explained again at this point.

3 shows a supply position of the circuit board according to the invention according to a third preferred embodiment in a plan view. The supply situation is again a metal layer 600 that have a middle area 100 and a border area 102 having. At the edge 102 has the metal layer 600 continuing interruptions 602 on, which include a conical geometry, as z. B. also be used in the lining of EMC measurement rooms to suppress waveguide resonances of the measuring space. These interruptions 602 are with the conductive material 104 filled, leaving the edge area 102 through the conductive material 104 gives a conductive structure through which the center region 100 the metal layer 600 is surrounded.

Alternatively to the in 3 shown conical geometry of the interruptions 602 fractal edge geometries are also considered.

Through the in 3 shown third preferred embodiment of a supply layer of the circuit board according to the invention using conical geometries of the interruptions 602 (or alternatively to use edge geometries of the interruptions 602 ) can thus be again in the edge area 102 an attenuation or absorption of a switching operations of the components in the central region 100 achieve generated wave. This is again a significant reduction of wave reflections in the edge area 102 the metal layer 600 and achieved a significant reduction of noise emissions from the circuit board.

The 1 to 3 described preferred embodiments of the circuit board according to the invention have been explained with reference to a single supply layer of the circuit board. However, the present invention is not limited to the use of a single supply layer circuit board; Rather, circuit boards with two or more supply layers are also suitable for supplying components to be arranged on the circuit board with an electrical potential, wherein at least one supply layer has a damping structure. The individual supply layers are each separated by a dielectric layer, with adjacent supply layers each forming a waveguide. The individual supply layers can each be subjected to one of a plurality of electrical potentials (for example, a negative electrical potential, a positive electrical potential or a ground potential), wherein a to be disposed on the circuit board component with a difference between the electrical potentials of two separate supply layers can be supplied ,

4 shows a fourth preferred embodiment of a circuit board according to the invention in cross-sectional view. According to the fourth preferred embodiment of the circuit board according to the invention, the circuit board comprises another substrate 400 with a first main surface 402 and a second major surface 404 , On the second main surface 404 the further substrate 400 is another metal layer 406 arranged. On the further metal layer 406 is a dielectric layer 408 arranged. Further, on the dielectric layer 408 the metal layer 600 arranged on which the substrate 200 is arranged, wherein the substrate 200 a first main surface 410 and a second main surface 412 includes and second major surface 412 of the substrate 200 the metal layer 600 touched. The metal layer 600 again has a middle section 100 and a border area 102 on. At the edge 102 the metal layer 600 are again interruptions 602 formed The further metal layer 406 also has a middle section 420 and a border area 422 on.

According to the fourth preferred embodiment of the present invention, the breaks are 602 the metal layer 600 through a discrete ohmic resistance 430 bridged on the first main surface 410 of the substrate 200 is arranged and by means of vias 432 with the metal layer 600 is conductively connected. The further metal layer 406 points in the edge area 422 also interruptions 440 on, by means of a discrete ohmic resistance 442 which is at the first main surface 402 the further substrate 400 is arranged, bridged and via vias 444 with the further metal layer 406 are connected.

By the in 4 As shown in the structure of a circuit board according to the fourth embodiment of the present invention, it is possible to provide a supply system having two different supply layers, the individual supply layers passing through the metal layer 600 and the other metal layer 604 are formed. By the in 4 Furthermore, it is possible, through the discrete resistors 430 and 442 one by switching operations in the middle area 100 . 420 resulting wave in the edge area 102 . 422 to attenuate themselves along the through the metal layer 600 and the other metal layer 406 trained waveguide moves. Such a structure is particularly advantageous when, in addition to the conductor material in the metal layer 600 and the other metal layer 406 (which usually includes copper material) does not allow any additional material to be integrated in the metal layer. Due to the discrete ohmic resistances 430 and 442 on the first main surface 410 of the substrate 200 and the first main surface of the further substrate 400 will be in contact with the vias 432 . 444 a damping effect in the edge area 102 . 422 reaches the waveguide, the damping effect of the structuring of the edge region described above 102 the metal layer 600 equivalent.

Analogous to the in 4 In the illustrated structure of a circuit board according to the invention can be used to attenuate waves on the supply system instead of the discrete ohmic resistors and ferrite beads, which are arranged on the first main surface of the substrate and the first main surface of the other substrate and are DC isolated from the supply layer. By ferrite beads can be the edge area 102 . 422 with the middle area 100 . 420 for low frequencies connect low ohmic. High frequencies, on the other hand, are strongly damped.

In 5 a fifth preferred embodiment of the circuit board according to the invention is shown in cross-sectional view. In the 5 shown circuit board in this case again comprises a further substrate 400 with a first main surface 402 and a second major surface 404 , On the second main surface 404 is another metal layer 406 arranged. On the further metal layer 406 is a dielectric layer 408 arranged on which the metal layer 600 is arranged. On the metal layer 600 is the substrate 200 with the first main surface 410 and the second main surface 412 arranged, wherein the substrate 200 over the second main surface 412 with the metal layer 600 connected is. Furthermore, the circuit board includes adjacent to the side edge 110 the circuit board an insulation layer 500 through which the metal layer 600 and the other metal layer 604 electrically from the side edge 110 the circuit board are isolated. Furthermore, the circuit board according to the invention according to the fifth preferred embodiment comprises a conductive frame 502 , external to the side edge 110 the circuit board is arranged. The conductive frame 502 preferably has a U-shaped profile, wherein the conductive frame 502 so on the side edge 110 the circuit board is arranged that through the conductive frame 502 the side edge 110 , a partial area of the first main surface 410 of the substrate 200 and a portion of the first main surface 402 the further substrate 400 is covered. The conductive frame 502 is also capacitive with the metal layer 600 and the other metal layer 406 coupled. Furthermore, the conductive frame 502 a material that has a higher resistance than the metal layer 600 or the further metal layer 406 ,

By the in 5 shown structure of a circuit board according to the invention can be in the central region 100 the metal layer 600 or in the middle range 420 the further metal layer 406 By switching operations resulting waves attenuate the fact that the waves on the capacitive coupling in the edge region 102 the metal layer 600 or the border area 422 the further metal layer 406 in the conductive frame 502 in which the wave energy is due to the higher resistance of the conductive frame 502 against the resistance of the metal layer 600 or the further metal layer 406 is converted into heat. The metal layer 600 and the other metal layer 406 Thus provide a broadband low-impedance supply system at the same time low noise levels and good attenuation of high frequencies available, the use of the conductive frame 502 Of the described damping structures the smallest space requirement on the board erfodert.

Claims (18)

Circuit boards having the following features: an electrically conductive layer ( 600 ), which can be acted upon to supply components to be arranged on the circuit board with an electrical potential, wherein the position ( 600 ) a middle area ( 100 ) and a border area ( 102 ) having; and a damping structure with a resistance that is connected to the edge area (FIG. 102 ) the situation ( 600 ) is coupled in such a way that one moves along the position ( 600 ) propagating wave due to the resistance of the damping structure at the edge region ( 102 ) the situation ( 600 ) stronger than in the middle ( 100 ) the situation ( 600 ) is dampened. Circuit board according to claim 1, comprising an electrically conductive further layer ( 406 ) for supplying components which can be arranged on the circuit board, wherein the further position ( 406 ) of the situation ( 600 ) through a dielectric ( 408 ), the further position ( 604 ) can be acted upon by a further electrical potential, and wherein a component with a difference between the electrical potential and the further electrical potential can be supplied. Circuit board according to claim 2, wherein the electrical Potential is a positive potential and the more electrical Potential is a negative potential, or where the electrical Potential is a positive potential and the more electrical Potential is a ground potential. Circuit board according to one of Claims 1 to 3, in which the electrically conductive layer ( 600 ) a metal layer ( 600 ) on a substrate ( 200 ), in which the metal layer ( 600 ) in the middle area ( 100 ) is continuous, in which the metal layer ( 600 ) in the border area ( 102 ) a break ( 602 ), in which the damping structure comprises a conductive material ( 104 ) in the interruption ( 602 ) and has a resistance which is higher than a resistance of the metal layer ( 600 ); and in which the edge area ( 102 ) starting from an imaginary edge of the uninterrupted metal layer ( 600 ) by a predetermined distance ( 106 ) which is less than 10% of an overall dimension ( 108 ) of the metal layer ( 600 ) in the direction of the predetermined distance ( 106 ). Circuit board according to Claim 4, in which the predetermined distance ( 106 ) has a value between 3 mm and 5 mm. Circuit board according to Claim 4, in which the peripheral area ( 102 ) the middle range ( 100 ) surrounds. Circuit board according to one of Claims 4 to 6, in which the interruption ( 602 ) in the metal layer ( 600 ) has a honeycomb structure, wherein the honeycomb structure comprises polygons having at least three corners. Circuit board according to one of Claims 4 to 7, in which the interruption ( 602 ) in the metal layer ( 600 ) continuously around the middle area ( 100 ) is arranged. Circuit board according to one of Claims 4 to 6, in which the interruption ( 602 ) in the metal layer ( 600 ) has a conical structure. Circuit board according to one of Claims 4 to 6, in which the interruptions ( 602 ) in the metal layer ( 600 ) has a fractal edge geometry. Circuit board according to one of Claims 4 to 6, in which the interruption ( 602 ) of the metal layer ( 600 ) in the border area ( 102 ) by a discrete ohmic resistance ( 430 . 442 ) is bridged. Circuit board according to claim 11, wherein the substrate ( 200 ) a first main surface ( 410 ) and a second main surface ( 412 ), in which the metal layer ( 600 ) on the second main surface ( 412 ) and the discrete ohmic resistance ( 430 ) on the first main surface ( 410 ), wherein the substrate vias ( 432 ), via which the discrete ohmic resistance ( 430 ) with the metal layer ( 600 ) is conductively connected. A circuit board according to claim 1, wherein said damping structure is one of said electrically conductive layer ( 600 ) DC-isolated discrete element which in the edge region ( 102 ) the situation ( 600 ), wherein the discrete element comprises a material having electrical or magnetic losses. A circuit board according to claim 13, wherein said discrete element comprises a ferrite bead. Circuit board according to claim 13, wherein the layer ( 600 ) at the edge area ( 102 ) from a side edge ( 110 ) of the circuit board is electrically isolated and wherein the damping structure comprises a conductive frame ( 502 ), which at the side edge ( 110 ) of the scarf circuit board arranged and capacitive with the position ( 600 ) is coupled. Circuit board according to Claim 2, in which the further layer ( 406 ) on another substrate ( 400 ) is applied. Circuit board according to Claim 15 or 16, in which the further layer ( 406 ) capacitively with the conductive frame ( 502 ) is coupled. Circuit board according to Claim 2, in which the further layer ( 406 ) a middle area ( 420 ) and a border area ( 422 ), wherein furthermore a further damping structure with a resistance at the edge region (FIG. 422 ) of the further situation ( 406 ) is coupled with the same.