Component Carrier With Bridge Structure In Through Hole Fulfilling Minimum Distance Design Rule

Abstract

A component carrier with an electrically insulating layer structure has opposed main surfaces, a through-hole, and an electrically conductive bridge structure connecting opposing sidewalls delimiting the through-hole. The sidewalls have a first tapering portion extending from a first main surface and a second tapering portion extending from a second main surface. A first demarcation surface faces the first main surface and a second demarcation surface faces the second main surface. A central bridge plane extends parallel to the first main surface and the second main surface and is at a vertical center between a lowermost point of the first demarcation surface and an uppermost point of the second demarcation surface. A first intersection point is between the central bridge plane and one of the sidewalls delimiting the through hole. A length of a shortest distance from the first intersection point to the first demarcation surface is at least 8 m.

Claims

1. A component carrier, comprising: an electrically insulating layer structure having a first main surface and a second main surface; a through hole, in particular a laser through hole, extending through the electrically insulating layer structure between the first main surface and the second main surface; and an electrically conductive bridge structure connecting opposing sidewalls delimiting the through hole; wherein the through hole has a first tapering portion extending from the first main surface and a second tapering portion extending from the second main surface; wherein the electrically conductive bridge structure is delimited by a first demarcation surface facing towards the first main surface and by a second demarcation surface facing towards the second main surface; wherein a central bridge plane is defined to extend parallel to the first main surface and the second main surface and at a vertical center between a lowermost point of the first demarcation surface and an uppermost point of the second demarcation surface; wherein a first intersection point is defined as a first intersection between the central bridge plane and one of the sidewalls delimiting the through hole; wherein a length of a shortest distance, in particular a length of a first perpendicular, from the first intersection point to the first demarcation surface is at least 8 m.

2. The component carrier according to claim 1, further comprising at least one of the following features: the length of the shortest distance, in particular the length of the first perpendicular, from the first intersection point to the first demarcation surface is at least 15 m; the length of the shortest distance, in particular the length of the first perpendicular, from the first intersection point to the first demarcation surface is in a range between 20 m and 40 m, in particular between 20 m and 30 m; a length of a shortest distance, in particular a length of a second perpendicular, from the first intersection point to the second demarcation surface is at least 8 m, in particular at least 15 m, more particularly in a range between 20 m and 40 m, preferably between 20 m and 30 m.

3. The component carrier according to claim 1, wherein a second intersection point is defined as a second intersection between the central bridge plane and another one of the sidewalls delimiting the through hole, wherein a length of a shortest distance, in particular a length of a third perpendicular, from the second intersection point to the first demarcation surface is at least 8 m, in particular at least 15 m, more particularly in a range between 20 m and 40 m, preferably between 20 m and 30 m.

4. The component carrier according to claim 3, wherein a length of a shortest distance, in particular a length of a fourth perpendicular, from the second intersection point to the second demarcation surface is at least 8 m, in particular at least 15 m, more particularly in a range between 20 m and 40 m, preferably between 20 m and 30 m.

5. The component carrier according to claim 1, wherein a circumferential intersection line is defined by connecting all intersection points corresponding to an intersection between the central bridge plane and circumferential sidewalls delimiting the through hole; wherein a length of all shortest distances, in particular a length of all perpendiculars, from the circumferential intersection line to the first demarcation surface is at least 8 m, in particular at least 15 m, more particularly in a range between 20 m and 40 m, preferably between 20 m and 30 m.

6. The component carrier according to claim 5, wherein a length of all shortest distances, in particular a length of all perpendiculars, from the circumferential intersection line to the second demarcation surface is at least 8 m, in particular at least 15 m, more particularly in a range between 20 m and 40 m, preferably between 20 m and 30 m.

7. The component carrier according to claim 1, comprising at least one of the following features: a thickness of the electrically insulating layer structure is less than 100 m, in particular less than 60 m, more particular in a range between 30 m and 60 m; the electrically insulating layer structure is a core, in particular a fully cured core; the bridge structure also covers at least part of the sidewalls; the bridge structure is composed of a seed layer being covered with a plating layer.

8. The component carrier according to claim 1, further comprising: a first electrically conductive bulk structure filling at least part of a volume between the first demarcation surface and the first main surface; and/or a second electrically conductive bulk structure filling at least part of a volume between the second demarcation surface and the second main surface.

9. The component carrier according to claim 8, wherein at least one of the first electrically conductive bulk structure and the second electrically conductive bulk structure is a plating structure.

10. The component carrier according to claim 1, wherein at least one of a first electrically conductive layer structure on the first main surface and a second electrically conductive layer structure on the second main surface is a patterned electrically conductive layer structure.

11. The component carrier according to claim 1, further comprising at least one of the following features: at least a part of the through hole is substantially X-shaped; at least a part of the through hole has a central, in particular substantially cylindrical, section between the two opposing tapering sections; at least one of the first demarcation surface and the second demarcation surface has a concave shape; a cross-section of the bridge structure is substantially H-shaped; a narrowest vertical thickness of the bridge structure is at least 20 m; a narrowest horizontal width of the through hole is not more than 100 m, in particular not more than 75 m; a narrowest horizontal width of the through hole is not less than 30 m, in particular not less than 45 m; a narrowest diameter of the through hole is in a range between 55 m and 70 m.

12. The component carrier according to claim 1, further comprising at least one of the following features: at least one component embedded in the component carrier, wherein the at least one component is in particular selected from a group consisting of an electronic component, an electrically non-conductive and/or electrically conductive inlay, a heat transfer unit, a light guiding element, an energy harvesting unit, an active electronic component, a passive electronic component, an electronic chip, a storage device, a filter, an integrated circuit, a signal processing component, a power management component, an optoelectronic interface element, a voltage converter, a cryptographic component, a transmitter and/or receiver, an electromechanical transducer, an actuator, a microelectromechanical system, a microprocessor, a capacitor, a resistor, an inductance, an accumulator, a switch, a camera, an antenna, a magnetic element, a further component carrier, and a logic chip; at least one electrically conductive layer structure of the component carrier includes at least one element of a group of elements consisting of copper, aluminum, nickel, silver, gold, palladium, and tungsten, any of the mentioned elements being optionally coated with supra-conductive material such as graphene; the electrically insulating layer structure comprises at least one of a group consisting of resin, in particular reinforced or non-reinforced resin, for instance epoxy resin or Bismaleimide-Triazine resin, FR-4, FR-5, cyanate ester, polyphenylene derivate, glass, prepreg material, polyimide, polyamide, liquid crystal polymer, epoxy-based build-up material, polytetrafluoroethylene, a ceramic, and a metal oxide; the component carrier is shaped as a plate; the component carrier is configured as one of a group consisting of a printed circuit board, and a substrate; the component carrier is configured as a laminate-type component carrier.

13. A method of manufacturing a component carrier, the method comprising: forming a through hole, in particular a laser through hole, extending between a first main surface and a second main surface of an electrically insulating layer structure, wherein the through hole is formed with a first tapering portion extending from the first main surface and a second tapering portion extending from the second main surface; and forming an electrically conductive bridge structure connecting opposing sidewalls delimiting the through hole, wherein the electrically conductive bridge structure is formed to be delimited by a first demarcation surface facing towards the first main surface and by a second demarcation surface facing towards the second main surface; wherein a central bridge plane is defined to extend parallel to the first main surface and the second main surface and at a vertical center between a lowermost point of the first demarcation surface and an uppermost point of the second demarcation surface; wherein a first intersection point is defined as a first intersection between the central bridge plane and one of the sidewalls delimiting the through hole; wherein the electrically conductive bridge structure is formed so that a length of a shortest distance, in particular a length of a first perpendicular, from the first intersection point to the first demarcation surface is at least 8 m.

14. The method according to claim 13, wherein forming the through hole comprises a first drilling with a laser from the first main surface with one laser shot and a second drilling with a laser from the second main surface with one laser shot.

15. The method according to claim 13, wherein forming the through hole comprises a first drilling with a laser from the first main surface with one laser shot and a second drilling with a laser from the second main surface with two laser shots.

16. The method according to claim 13, wherein forming the electrically conductive bridge structure is carried out by plating, in particular following a seed layer formation.

17. The method according to claim 13, further comprising: forming a first electrically conductive bulk structure filling at least part of a volume above the first demarcation surface and/or forming a second electrically conductive bulk structure filling at least part of a volume below the second demarcation surface.

18. The method according to claim 17, wherein forming at least one of the group consisting of the first electrically conductive bulk structure and the second electrically conductive bulk structure by at least one further plating procedure following a previous plating procedure of forming the bridge structure.

19. The method according to claim 13, further comprising: before forming the through hole: providing a first electrically conductive layer structure on the first main surface; and/or providing a second electrically conductive layer structure on the second main surface.

20. The method according to claim 13, wherein forming the through hole is performed while at least one of the main surfaces of the electrically insulating layer structure is covered by an electrically conductive layer structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5 and FIG. 6 illustrate cross-sectional views of structures obtained while performing example methods of manufacturing a component carrier with a through hole by a multiple laser shot treatment from opposing sides and by subsequently filling a through hole at least partially with electrically conductive filling medium according to an exemplary embodiment of the invention.

[0051] FIG. 2A shows a cross-sectional view of a preform of a component carrier according to another exemplary embodiment relating to FIG. 2 but with the difference that no electrically conductive layer structures are provided on the opposing main surfaces of the electrically insulating layer structure at the time of forming the through hole.

[0052] FIG. 7 illustrates a schematic cross-sectional view of a component carrier with through hole according to an exemplary embodiment of the invention.

[0053] FIG. 8 illustrates an example of a realistic cross-sectional view of a component carrier with through hole according to an exemplary embodiment of the invention.

[0054] FIG. 9 illustrates cross-sectional views of preforms of a component carrier manufactured in accordance with a manufacturing method according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0055] The illustrations in the drawings are schematically presented. In different drawings, similar or identical elements are provided with the same reference signs.

[0056] FIG. 1 to FIG. 6 illustrate cross-sectional views of structures obtained while manufacturing a component carrier 100, shown in FIG. 6, with a through hole 108 by a multiple laser shot treatment from opposing sides and by subsequently filling a through hole 108 with electrically conductive filling medium formed by multiple filling procedures according to an exemplary embodiment of the invention.

[0057] Referring to FIG. 1, a first part of the through hole 108 extending between a first main surface 104 and a second main surface 106 of an electrically insulating layer structure 102 is formed by carrying out a first laser shot 115. Laser processing as described referring to FIG. 1 to FIG. 3 may be carried out by an appropriate laser source, for instance by an excimer laser and/or a carbon dioxide laser. In the illustrated embodiment, the electrically insulating layer structure 102 may comprise resin (in particular epoxy resin), optionally comprising reinforcing particles such as glass fibers or glass spheres. A vertical thickness D of the electrically insulating layer structure 102 may for instance be not more than 100 m, in particular in a range between 40 m and 60 m.

[0058] A blind hole 113 is formed by the first laser shot 115 in the upper main surface 104 of the electrically insulating layer structure 102. The blind hole 113 later constitutes a first tapering portion 114 of the through hole 108 completed according to FIG. 2 or FIG. 3. The first laser shot 115 also forms a window or through hole extending through a first electrically conductive layer structure 152, which may for instance be a metal layer such as a copper foil, on the first main surface 104 of the electrically insulating layer structure 102. The first electrically conductive layer structure 152 may have a thickness d1 of less than 5 m, in particular in a range between 2 m and 3 m.

[0059] Care should be taken in terms of selection of laser energy and duration of the first laser shot 115 that the first laser shot 115 does not reach up to a second electrically conductive layer structure 154 on the second main surface 106 of the electrically insulating layer structure 102, because reflection of the laser light from the second electrically conductive layer structure 154 might result in an undesired shape of the formed through hole 108. The second electrically conductive layer structure 154 may for instance be a metal layer such as a copper foil and may have a thickness d2 of less than 5 m, in particular in a range between 2 m and 3 m.

[0060] Referring to FIG. 2, the process of forming the through hole 108 is continued, after carrying out the first laser drilling from the first main surface 104 with one laser shot 115 as described referring to FIG. 1, by carrying out a second laser drilling from the second main surface 106 with one further laser shot 117, i.e. by altogether two laser shots 115, 117. Thereby, the illustrated through hole 108 is formed with a first tapering portion 114 extending from the first main surface 104 and resulting from the first laser shot 115, and with a second tapering portion 116 extending from the second main surface 106 and resulting from the second laser shot 117.

[0061] As can be taken from FIG. 2, the second laser shot 117 is carried out after the first laser shot 115 and from the back side, i.e. forming a through hole through the second electrically conductive layer structure 154 and extending the previously formed blind hole 113 into the through hole 108 extending through the entire thickness of the electrically insulating layer structure 102. After the first laser shot 115 and before the second laser shot 117, the structure shown in FIG. 1 may be flipped or turned around by 180 so that the laser source (not shown) may remain stationary.

[0062] In one embodiment, the obtained through hole 108 with a substantial X-shape as shown in FIG. 2 may be made subject to a procedure of filling the through hole 108 with electrically conductive material such as copper. Thus, the procedures illustrated and described below referring to FIG. 4 to FIG. 6 can also start on the basis of through hole 108 with substantial X-shape as shown in FIG. 2. Alternatively, it is possible to carry out a further laser shot 119 before filling the through hole 108 with electrically conductive material, as will be described referring to FIG. 3.

[0063] Referring to the alternative of FIG. 3, forming the through hole 108 comprises carrying out, in addition to the first laser drilling from the first main surface 104 with one laser shot 115 and in addition to the second laser drilling from the second main surface 106 with the second laser shot 117, a third laser drilling by a third laser shot 119 from the backside as well. FIG. 3 shows how a third laser shot 119 is carried out from the back side or from the second main surface 106 of the electrically insulating layer structure 102 following the procedure described referring to FIG. 2. By taking this measure, the shape of the through hole 108 can be further manipulated so that the narrowest portion of the through hole 108 is spatially widened and a for instance substantially circular cylindrical central connection portion 134 is formed between the tapering portions 114, 116.

[0064] In order to obtain the layer structure shown in FIG. 4, the through hole 108 according to FIG. 3 is made subject to a first procedure of filling it with an electrically conductive filling medium such as copper. In order to accomplish this, it is preferable to firstly carry out an electroless deposition procedure to thereby form a thin seed layer 144 of copper directly covering the sidewalls 112 of the electrically insulating layer structure 102 delimiting the through hole 108. This can be seen in a detail 121 in FIG. 4. A thickness of the seed layer 144 may be for instance 0.5 m. However, it is also possible that the seed layer 144 has a thickness above 1 m and/or that several cumulative seed layers are provided. For example, a thickness of a seed layer 144 or a cumulative thickness of a plurality of seed layers may be in a range between 0.5 m and 5 m. When multiple seed layers are provided, they may comprise an organic (for instance polymer) layer, a palladium layer, and/or a copper layer.

[0065] Subsequently, further electrically conductive material (such as copper) may be deposited on the seed layer 144 by a plating procedure, in particular by galvanic plating. Thus, the sidewalls 112 as well as the electrically conductive layer structures 152, 154 are covered by a thicker plating layer 146 of electrically conductive filling medium such as copper. For instance, the plating layer 146 may have a thickness of 10 m.

[0066] Referring to FIG. 5, the plating procedure described referring to FIG. 4 is continued so as to form an electrically conductive bridge structure 110 with a substantially horizontal portion connecting opposing sidewalls 112 of the through hole 108. As shown, the electrically conductive bridge structure 110 is formed to be delimited by an upper first demarcation surface 118 oriented upwardly or facing towards the first main surface 104 and by a lower second demarcation surface 120 orientated downwardly or facing towards the second main surface 106. Forming the electrically conductive bridge structure 110 may be carried out by galvanic plating, preferably following the formation of the seed layer 144 described referring to FIG. 4. Thus, the bridge structure 110 is composed of seed layer 144 being covered with plating layer 146 and forms a substantially horizontal bridge between opposing sidewalls 112 of the electrically insulating layer structure 102 delimiting the through hole 108.

[0067] A virtual central bridge plane 122 is defined to extend parallel to the first main surface 104 and parallel to the second main surface 106 and at a height corresponding to a vertical center 124 or midpoint between a lowermost point 126 of the first demarcation surface 118 and an uppermost point 128 of the second demarcation surface 120. Moreover, a virtual first intersection point 130 is defined as a first intersection between the central bridge plane 122 and one of the sidewalls 112 of the electrically insulating layer structure 102. According to a highly advantageous design rule resulting in a highly reliable component carrier 100, the electrically conductive bridge structure 110 is formed so that a length 11 of a shortest distance or first perpendicular 132 from the first intersection point 130 to the first demarcation surface 118 is at least 8 m, preferably at least 15 m.

[0068] Thus, FIG. 5 shows a layer structure obtained when continuing the plating procedure described referring to FIG. 4. In the region of the narrowest portion of the through hole 108, the substantially horizontal bridge structure 110 is formed connecting the opposing sidewalls 112. A concave upper limiting surface corresponds to the first demarcation surface 118, whereas a lower concave limiting surface of the bridge structure 110 corresponds to the second demarcation surface 120. At a vertically intermediate position between the bottom end of the first demarcation surface 118 and a top end of the second demarcation surface 120, the central bridge plane 122 is obtained as a virtual plane being parallel to the first main surface 104 and the second main surface 106 so that all three of the mentioned planes extend horizontally according to the paper plane of FIG. 5, i.e. perpendicular to a stacking direction of the layer structures 102, 152, 154 of the component carrier 100 to be manufactured.

[0069] A circumferential intersection line is formed when intersecting the virtual central bridge plane 122 with the three-dimensional area defining the sidewall 112 delimiting the through hole 108. One intersection point between the central bridge plane 122 and the sidewalls 112 is denoted with reference numeral 130 in FIG. 5. When virtually connecting intersection point 130 with first demarcation surface 118 so that the corresponding connection line, see the perpendicular 132, is perpendicular to a tangent (in particular tangent plane) of the curved first demarcation surface 118, a design parameter 11 is obtained. As will be described below in further detail referring to FIG. 7 and FIG. 8, the minimum distance 11 should be at least 8 m, preferably at least 15 m to obtain very good reliability results of the readily manufactured component carrier 100.

[0070] Although not shown in FIG. 5, the geometry of the through hole 108 may result, when carrying out a plating process, in the formation of bridge structure 110 laterally connecting opposing sidewalls 112 of the electrically insulating layer structure 102 delimiting the through hole 108 at a vertical level at which the distance to the first main surface 104 is different from the distance to the second main surface 106. This may promote the formation of a free hanging, asymmetrical bridge structure 110 located out of a vertical center of the through hole 108.

[0071] Referring to FIG. 6, a first electrically conductive bulk structure 148 filling a major part between the first demarcation surface 118 and the first main surface 104 and a second electrically conductive bulk structure 150 filling a major part between the second demarcation surface 120 and the second main surface 106 are formed. This can be done by carrying out one or more further galvanic plating procedures following the previous plating procedure of forming the bridge structure 110.

[0072] Thus, the component carrier 100 according to FIG. 6 can be obtained by carrying out one or more further plating procedures. Thereby, the bulk structures 148, 150, which may for instance consist of copper, can be obtained. In the shown embodiment, a small dip 125, 127, respectively, remains at an upper side or a lower side of the shown component carrier 100. In other embodiments, the bulk structures 148, 150 fill the remaining recesses above the first demarcation surface 118 and below the second demarcation surface 120 almost completely. It should be said that it is well-known by a skilled person that the demarcation surfaces 118, 120 are clearly visible when imaging a cross-section of the component carrier 100.

[0073] FIG. 7 illustrates a schematic cross-sectional view of a component carrier 100 with through hole 108 according to an exemplary embodiment of the invention. According to FIG. 7, the through hole 108 is substantially X-shaped. For instance, such a substantial X-shape may be defined, referring to a cross-sectional view of the component carrier 100 or its preform, by sidewall lines corresponding to two opposing vertical bows having their maxima facing each other in a central portion of the through hole 108. The shape of the through hole 108 may hence also be denoted as the shape of a vertical bow tie or of a mirrored truncated cone structure. FIG. 8 illustrates a realistic cross-sectional view of a component carrier 100 with a through hole 108 according to an exemplary embodiment of the invention. According to FIG. 8, two opposing exterior portions of the through hole 108 are tapering, whereas a central portion of the through hole is substantially cylindrical.

[0074] In the illustrated embodiments, the example component carriers 100 can be laminate-type plate-shaped component carriers 100 such as a printed circuit board (PCB). The component carriers 100 may comprise a layer stack composed of the central electrically insulating layer structure 102 being covered on each of its opposing main surfaces 104, 106 by a respective one of the two electrically conductive layer structures 152, 154. Preferably, the electrically insulating layer structure 102 is made of a fully cured material such as FR4. The electrically conductive layer structures 152, 154 may be patterned copper foils.

[0075] The through hole 108 extending through the electrically insulating layer structure 102 between the first main surface 104 and the second main surface 106 is filled in a central portion thereof with electrically conductive filling medium such as copper. This electrically conductive filling medium comprises the electrically conductive bridge structure 110 connecting opposing sidewalls 112 of the through hole 108. In the configuration of FIG. 8, the through hole 108 comprises a central connection portion 134 connecting the first tapering portion 114 with the second tapering portion 116, and the horizontal section of the bridge structure 110 is located in the central connection portion 134 (concerning the reference numerals, compare FIG. 3). In the configuration of FIG. 7, the horizontal section of the bridge structure 110 is located around a narrowest portion of the substantially X-shaped through hole 108. Apart from its substantially horizontal section, the bridge structure 110 also covers the sidewalls 112 and there-fore has a substantial H shape, both in FIG. 7 and in FIG. 8.

[0076] As mentioned above, the electrically conductive bridge structure 110 is delimited at an upper side by first demarcation surface 118 facing towards the first main surface 104 and at a lower side by second demarcation surface 120 facing towards the second main surface 106. The virtual central bridge plane 122 is defined to extend parallel to the first main surface 104 and the second main surface 106 and at a vertical center 124 between a lowermost point 126 of the first demarcation surface 118 and an uppermost point 128 of the second demarcation surface 120. A vertical distance between the lowermost point 126 and the vertical center 124 equals to a vertical distance between the uppermost point 128 and the vertical center 124. A virtual first intersection point 130 is defined as a first intersection between the central bridge plane 122 and the sidewall 112 of the electrically insulating layer structure 102 on the left-hand side of FIG. 7 and FIG. 8.

[0077] Advantageously, a length 11 of a shortest distance or a first perpendicular 132 from the first intersection point 130 to the first demarcation surface 118 is at least 8 m, preferably at least 15 m, and most preferably the length 11 is in the range between 20 m and 30 m, to obtain very good results in terms of electric reliability of the component carrier 100. Correspondingly, a length 12 of a shortest distance or a second perpendicular 136 from the first intersection point 130 to the second demarcation surface 120 is at least 8 m, preferably at least 15 m, and most preferably between 20 m and 30 m.

[0078] Accordingly, a virtual second intersection point 138 is defined as a second intersection between the central bridge plane 122 and the sidewalls 112 of the electrically insulating layer structure 102 on the right-hand side of FIG. 8. A length 13 of a shortest distance or a third perpendicular 140 from the second intersection point 138 to the first demarcation surface 118 is at least 8 m, preferably at least 15 m, and most preferably between 20 m and 30 m. Correspondingly, a length 14 of a shortest distance or a fourth perpendicular 142 from the second intersection point 138 to the second demarcation surface 120 is at least 8 m, preferably at least 15 m, and most preferably between 20 m and 30 m.

[0079] In the virtual central bridge plane 122 perpendicular to the paper plane of FIG. 7 and FIG. 8, a virtual circumferential intersection line (not shown) is defined by connecting all intersection points (130, 138, etc.) corresponding to an intersection between the central bridge plane 122 and circumferential sidewalls 112 of the electrically insulating layer structure 102. Particularly satisfying results in terms of electric reliability of the component carrier 100 can be obtained when a length of all shortest distances or perpendiculars from the circumferential intersection line to the first demarcation surface 118 is at least 8 m, preferably at least 15 m, and most preferably between 20 m and 30 m. Correspondingly, a length of all shortest distances or all perpendiculars from the circumferential intersection line to the second demarcation surface 120 may be at least 8 m, preferably at least 15 m, and most preferably between 20 m and 30 m, to obtain particularly pronounced advantages in terms of reliability.

[0080] As mentioned above, thickness D of the electrically insulating layer structure 102 is preferably less than 100 m, so that the electrically insulating layer structure 102 forms a very thin fully cured core.

[0081] First electrically conductive bulk structure 148 fills a major part between the first demarcation surface 118 and the first main surface 104. Second electrically conductive bulk structure 150 fills a major part between the second demarcation surface 120 and the second main surface 106, wherein small dips 125, 127 may remain. Both the first electrically conductive bulk structure 148 and the second electrically conductive bulk structure 150 may be formed by carrying out one or multiple galvanic plating procedures which may be carried out after and separately from a plating procedure for the formation of the bridge structure 110.

[0082] A detail 135 in FIG. 8 illustrates exemplarily how the first perpendicular 132 may be constructed in order to define the described design rule in terms of improved reliability of the component carrier 100. The shortest connection between intersection point 130 and the first demarcation surface 118 is searched and is found by a connection line between intersection point 130 and first demarcation surface 118 which is perpendicular (see right angle in detail 135) to first demarcation surface 118. In other words, a tangent 133 to the first demarcation surface 118 (see auxiliary circle 131 at the intersection point 137) can thus be constructed. The design rule is fulfilled when the length 11 is larger than 8 m.

[0083] In order to obtain proper reliability of the component carrier 100 shown in FIG. 8, one or more of the following design rules may be fulfilled as well: A smallest vertical thickness B of the bridge structure 110 may be at least 20 m. A smallest horizontal distance C between opposing sidewalls 112 may be in a range between 55 m and 70 m. A horizontal dimension E1 of the window in the first electrically conductive layer structure 152 may be in the range between 65 m and 80 m. Correspondingly, a horizontal dimension E2 of the window in the second electrically conductive layer structure 154 may be in the range between 65 m and 80 m as well. The lateral overhang F1 between the first electrically conductive layer structure 152 and the sidewall 112 on the left-hand side of FIG. 8 may be in the range between 10 m and 15 m. The lateral overhang G1 between the first electrically conductive layer structure 152 and the sidewall 112 on the right-hand side of FIG. 8 may be in the range between 10 m and 15 m. The lateral overhang F2 between the second electrically conductive layer structure 154 and the sidewall 112 on the left-hand side of FIG. 8 may be in the range between 10 m and 15 m. The lateral overhang G2 between the second electrically conductive layer structure 154 and the sidewall 112 on the right-hand side of FIG. 8 may be in the range between 10 m and 15 m. Furthermore, when the condition F1F2 and/or G1G2 is fulfilled, particularly good results can be obtained in terms of reliability. Moreover, it has turned out advantageous for obtaining good reliability when a lateral offset between a center of the window in the first electrically conductive layer structure 152 and a window in the second electrically conductive layer structure 154 is not larger than 20 m.

[0084] What concerns the above described overhangs F1, F2, G1, G2 of overhanging material which may be locally not supported, it should be said that the respective overhang may relate to the substantially resin free area beneath the respective electrically conductive layer structure 152, 154. However, a person skilled in the art will understand that some residue resin might be even present within a gap relating to the overhang. In order to quantitatively determine or measure the value of the overhang, the length of the substantially resin-free (wherein resin may refer to the electrically insulating layer structure 102) undercut directly under an overhanging electrically conductive layer structure 152, 154 may be measured (in particular even if it is not the most receding point or total relief below the overhanging electrically conductive layer structure 152, 154, for example copper layer). In other words, for measuring the overhang, the undercut directly below the electrically conductive layer structure 102 may be measured.

[0085] FIG. 9 illustrates cross-sectional views of preforms of a component carrier 100 manufactured in accordance with a manufacturing method according to an exemplary embodiment of the invention. More specifically, FIG. 9 illustrates a sequence of cross-sections of a presently manufactured component carrier 100 showing the successive formation of a bridge structure 110 meeting design rules according to exemplary embodiments of the invention.

[0086] FIG. 2A shows a cross-sectional view of a preform of a component carrier 100 according to another exemplary embodiment relating to FIG. 2 but with the difference that no electrically conductive layer structures 152, 154 are provided on the opposing main surfaces 104, 106 of the electrically insulating layer structure 102 at the time of forming the through hole 108.

[0087] A main difference between the embodiment of FIG. 1 to FIG. 6 and the embodiment of FIG. 2A is that, according to FIG. 2A, the main surfaces 104, 106 of the electrically insulating layer structure 102 have not been covered by electrically conductive layer structures 152, 154 at the time of forming the through hole 108. Thus, the manufacturing method relating to the embodiment of FIG. 2A comprises forming the through hole 108 in the electrically insulating layer structure 102 while the main surfaces 104, 106 of the electrically insulating layer structure 102 have not been covered by an electrically conductive layer structure 152, 154 such as a copper foil.

[0088] What concerns the subsequent filling of the through hole 108 and coverage of the main surfaces 104, 106 with an electrically conductive filling medium, this may be carried out by the formation of an optional seed layer 144, the subsequent optional formation of a plating layer (not shown) covering at least part of the main surfaces 104, 106 and of the sidewalls 112 of the through hole 108, the subsequent formation of a bridge structure 110 bridging opposing sidewalls 112 and having for instance a substantially H-shape, and an optional filling of one or both volumes above and/or below the bridge structure 110 by one or more bulk structures 148, 150 (which may be further plating structures or sequences of plating structures). Reference is made to the corresponding description of FIG. 4 to FIG. 8.

[0089] Apart from this difference, the above disclosure concerning FIG. 1 to FIG. 6 also applies to FIG. 2A. Also, through hole formation according to FIG. 3 can be carried out without copper foils on the electrically insulating layer structure 102.

[0090] It should be noted that the term comprising does not exclude other elements or steps and the articles a or an do not exclude a plurality. Also, elements described in association with different embodiments may be combined.

[0091] Implementation of the invention is not limited to the preferred embodiments shown in the figures and described above. Instead, a multiplicity of variants is possible which variants use the solutions shown and the principle according to the invention even in the case of fundamentally different embodiments.