Component carrier with shielded cavity, antenna and non-conductive low loss high frequency structure above

Abstract

A component carrier (100) which comprises a stack (102) comprising a plurality of electrically conductive layer structures (150) and at least one electrically insulating layer structure (152), a cavity (104) formed in the stack (102) and being delimited by a peripheral wall, a conductive shielding (106) covering at least part of the peripheral wall of the cavity (104), a non-conductive low loss high frequency structure (154) above said cavity (104), and an antenna (108) at least partially above said low loss high frequency structure (154).

Description

[0001] Component carrier with shielded cavity, antenna and non-conductive low loss high frequency structure above

[0002] The invention relates to a component carrier and to a method for manufacturing a component carrier.

[0003] In the context of growing product functionalities of component carriers equipped with one or more electronic components and increasing miniaturization of such electronic components as well as a rising number of electronic components to be mounted on the component carriers such as printed circuit boards, increasingly more powerful array-like components or packages having several electronic components are being employed, which have a plurality of contacts or connections, with ever smaller spacing between these contacts. Removal of heat generated by such electronic components and the component carrier itself during operation becomes an increasing issue. At the same time, component carriers shall be mechanically robust and electrically reliable so as to be operable even under harsh conditions.

[0004] Moreover, artefacts may occur when high-frequency signals propagate along wiring structures of a component carrier. Such phenomena can substantially degrade the overall performance of a communication systems, etc.

[0005] It is an object of the invention to provide a component carrier with high performance, in particular in terms of high-frequency signal transmission.

[0006] In order to achieve the object defined above, a component carrier, and a method of manufacturing a component carrier according to the independent claims are provided.

[0007] According to an exemplary embodiment, a component carrier is provided which comprises a stack comprising a plurality of electrically conductive layer structures and at least one electrically insulating layer structure, a cavity formed in the stack and being delimited by a peripheral wall, a conductive shielding covering at least part of the peripheral wall of the cavity, a non- conductive low loss high frequency structure above said cavity, and an antenna at least partially above said low loss high frequency structure. According to another exemplary embodiment of the invention, a method of manufacturing a component carrier is provided, the method comprising forming a cavity in a stack comprising at least two electrically conductive layer structures and at least one electrically insulating layer structure, said cavity being delimited by a peripheral wall, forming a conductive shielding to cover at least part of the peripheral wall of the cavity, forming a non-conductive low loss high frequency structure above said cavity, and forming an antenna at least partially on top of said low loss high frequency structure.

[0008] According to still another exemplary embodiment of the invention, a component carrier having the above-mentioned features is used for a high- frequency application, in particular for conducting a radio frequency (RF) signal, in particular a radio frequency signal with a frequency above 1 GHz or even above 50 GHz, preferably of at least 75 GHz.

[0009] In the context of the present application, the term "component carrier" may particularly denote any support structure which is capable of accommodating one or more components thereon and / or therein for providing mechanical support and / or electrical connectivity. In other words, a component carrier may be configured as a mechanical and / or electronic carrier for components. In particular, a component carrier may be one of a printed circuit board, an organic interposer, and an IC (integrated circuit) substrate. A component carrier may also be a hybrid board combining different ones of the above mentioned types of component carriers.

[0010] In the context of the present application, the term "stack" may particularly denote an arrangement of multiple planar layer structures which are mounted in parallel on top of one another.

[0011] In the context of the present application, the term "layer structure" may particularly denote a continuous layer, a patterned layer or a plurality of non- consecutive islands within a common plane.

[0012] In the context of the present application, the term "cavity" may particularly denote a recess, groove or hole (in particular blind hole or through hole) extending up to and / or into the stack. Preferably, all the sides of the cavity may be defined by layer structures of the stack. The cavity may be configured to function as a waveguide, for example as an air-filled waveguide. In the context of the present application, the term "waveguide" may particularly denote a structure that guides waves, such as electromagnetic waves, with reduced loss of energy by restricting the transmission of energy to a limited number of directions, in particular, to one direction. Without the physical constraint of a waveguide, wave amplitudes decrease more quickly as they expand into the three dimensional space. For instance, a waveguide may be a hollow conductive recess in a layer stack of a component carrier which may be used to carry high frequency radio waves. For instance, a cross-section of a metallized recess (i.e. said cavity with conductive shielding) functioning as waveguide may be rectangular or circular. For example, a signal may be coupled with a waveguide using a stripline, i.e. a transverse electromagnetic transmission line such as a planar transmission line. Such a planar transmission line (for instance a stripline or a microstrip) may be provided at one side, for example the bottom, of the cavity. In particular, a signal may be coupled between waveguide and stripline at a waveguide-to-stripline transition. The stripline may be in direct contact with the waveguide or the stripline may be spatially spaced with regard to the waveguide. Furthermore at least one stripline, in particular a plurality of striplines, may be associated with the waveguide.

[0013] In the context of the present application, the term "conductive shielding" may particularly denote electrically conductive material (for example metal, such as copper, titanium, silver, palladium, gold, or conductive polymers, such as graphene) at least partially lining a peripheral wall delimiting the cavity in the stack. In particular, the conductive shielding or coating may partially or preferably entirely cover the cavity peripheral wall apart from the opening (and optionally apart from a second opening). Such a conductive shielding or coating may, for instance, be deposited on a peripheral wall of the cavity, for instance by plating, sputtering, etc. A conductive shielding may also be a metallic fence which may be formed by a plurality of electrically conductive posts or vias arranged around a circumference of the cavity sidewalls. The conductive shielding may comprise at least one layer (for instance only copper) or at least two layers (for example copper and titanium), wherein the layer or layers may be orientated perpendicular to the stacking direction.

[0014] In the context of the present application, the term "non-conductive low loss high frequency structure" may particularly denote an electrically insulating structure made of a dielectric material configured for enabling transmission of radio frequency waves with lower losses than prepreg (for example with not more than 80% or even not more than 50% of losses of ordinary prepreg). The non-conductive low loss high frequency structure may be made of a dielectric material leading to a lower loss of radiofrequency waves than the entire solid dielectric material being in contact with or surrounding said non- conductive low loss high frequency structure. Preferably, the non-conductive low loss high frequency structure may be embodied as a further cavity, such as an air-filled cavity. It is however also possible that the non-conductive low loss high frequency structure may be made of high-frequency-optimized solid material (such as low-DF materials). The provision of a non-conductive low loss high frequency structure in the stack may be implemented to improve R.F performance compared with an embodiment in which the non-conductive low loss high frequency structure is substituted by ordinary prepreg. In particular, the non-conductive low loss high frequency structure may be made of a low DK material, i.e. a material having a low DK value. In particular, the DK value of the non-conductive low loss high frequency structure may be less than 3.5 or less than 3.2, preferably in a range from 1.1 to 3.5. More generally, the range may be from 1.1 to 6.5. It can be even less than 10, the preferred value depends on the design, for instance it may be around 3. The loss tangent of such a material may be not more than 0.05, preferably not more than 0.005. Examples of suitable materials are low-loss FR4-grade materials, PTFE-based materials, polyimide materials, plastic or PTFE-based bonding sheet materials, and liquid crystal polymer (LCP). In a further embodiment, the non-conductive low loss high frequency structure may comprise a porous material. The porous material may comprise gas bubbles. In another embodiment, the non- conductive low loss high frequency structure may be free from filler material, in particular solid filler material, for example fibers (such as glass fibers) or spheres (such as glass spheres). Additionally or alternatively, the non- conductive low loss high frequency structure may have a thermal conductivity smaller than 1 W / mK, in particular in a range from 0.01 W / mK to 0.8 W / mK. Additionally or alternatively, the non-conductive low loss high frequency structure may be optically transparent. In the context of the present application, the term "antenna" may particularly denote a patterned electrically conductive structure or a surface mounted component (which may be electrically conductive or electrically insulating) configured to be capable of receiving and / or transmitting electromagnetic radiation signals, in particular radiofrequency (RF) signals, for instance of a specific frequency or frequency range. By such an antenna structure, which may be formed in and / or on the stack (in particular formed as an integral part of the stack) or as a surface mounted component, a signal may be coupled into the cavity-based waveguide or out of the cavity-based waveguide. An antenna may also be made of a dielectric material having a high DK value, in particular may be embodied as a dielectric resonator antenna (DRA).

[0015] In the context of the present application, the term "main surface" of a body may particularly denote one of two largest opposing surfaces of the body. The main surfaces may be connected by circumferential side walls. The thickness of a body, such as a stack, may be defined by the distance between the two opposing main surfaces.

[0016] According to an exemplary embodiment, a (for example laminated) layer stack-type component carrier (such as a PCB or an IC substrate) may be provided with a cavity formed inside of the stack. Peripheral walls of said cavity may be partially covered by an electrically conductive shielding (for example a metal lining) so that a low loss hollow waveguide may be formed by the cavity and its conductive shielding. Descriptively speaking, a cavity delimited by conductive shielding in a layer stack of a component carrier may function as a Faraday cage, promoting radiofrequency signal transmission with low loss and high signal integrity. The top-side of the cavity may be coupled with a non-conductive low loss high frequency structure (preferably a further cavity) which may have an impact on a better quality factor giving a higher antenna gain for an antenna above said low loss high frequency structure. Such a design may lead to a high-bandwidth, good directivity and / or high radiation efficiency. Exemplary embodiments may provide a waveguide cavity integrated in a stack with an antenna above and a non-conductive low loss high frequency structure (such as a further cavity or a region with a low DF RF dielectric) in between. Preferably, the non-conductive low loss high frequency structure may be located such that at least a portion of the non-conductive low loss high frequency structure intersects with the shortest distance between the antenna and the cavity or waveguide. By such an architecture, losses may be strongly reduced. An upper air cavity in addition to a lower waveguide cavity may lead to a better quality factor giving a higher antenna gain. For example, the non-conductive low loss high-frequency structure, which may be embodied preferably as an additional air cavity, may provide larger bandwidth and may optionally also function as a filter. More generally, the non-conductive low loss high-frequency structure may enhance system performance and may reduce losses by substituting non-low DF dielectric material, which would otherwise be present at the position of the non- conductive low loss high-frequency structure, by a low DF dielectric solid or air.

[0017] In particular, the described waveguide-antenna configuration with non- conductive low loss high-frequency structure in between, of a component carrier according to an exemplary embodiment may be fully compatible with very high frequencies even above 50 GHz, preferably at least 60 GHz. The combination of the above mentioned features of a cavity with conductive shielding, a non-conductive low loss high frequency structure (such as a further cavity) above, and an antenna still further above may lead to a component carrier with excellent high frequency behavior.

[0018] In the following, further exemplary embodiments of the component carrier and the method will be explained.

[0019] One preferred embodiment relates to an air-filled waveguide in combination with one or more dielectric resonator antennas (DRA) and / or one or more radiofrequency lenses.

[0020] In an embodiment, the low loss high frequency structure comprises a further cavity above said cavity (see for example Figure 1). The cavity and the further cavity may be in communication with each other, in particular in gas communication. An arrangement of two vertically stacked and connected cavities with a patterned electrically conductive layer structure forming part of the conductive shielding in between has turned out as a highly appropriate design for obtaining an excellent high frequency behavior. In an embodiment, said further cavity is air-filled or is filled with a low DK and / or low DF material. A low DK and / or low DF PCB material has a low dielectric constant (in particular having a DK value below 3.5 or even below 3.2) which extends over the entire width of the component carrier. As mentioned above, the further cavity may be filled with porous material (for instance like a sponge). The low DK and / or low DF material may be free from filler material, in particular solid filler material, for example (for instance glass) fibers or (for instance glass) spheres. The term DK refers specifically to the real part of the dielectric constant, while the term DF refers to the imaginary part. A low DK value means the wave propagation speed is large which may provide advantages in RF transmission by the PCB. When the further cavity is air-filled or is filled with a low DF material, radiofrequency losses may be kept very small.

[0021] In an embodiment, the further cavity is closed on a top side, in particular at least partially by said antenna. This may ensure a spatially very close arrangement of cavity, non-conductive low loss high frequency structure and antenna. As a result, a highly efficient electromagnetic wave coupling may be achieved, which may lead to low losses.

[0022] In an embodiment, the low loss high frequency structure comprises a layer of low DK and / or low DF material, in particular extending over an entire width of the stack. In particular, the non-conductive low loss high frequency structure may be embodied as a full layer of low DF dielectric which extends over the entire width of the component carrier. Preferably, the low loss high frequency structure may be made of a material different from the electrically insulating layer structures composing the stack. More specifically, the low loss high frequency structure may be made of a material having a lower DF value than said electrically insulating layer structures. This may lead to low loss radiofrequency properties along a propagation path of the electromagnetic waves between cavity, low loss high frequency structure, and antenna.

[0023] In an embodiment, peripheral walls delimiting the low loss high frequency structure are shielded by a conductive material (such as copper). The coating of the sidewalls of low loss high frequency structure by the conductive material may confine the electromagnetic fields and guide the electromagnetic fields within the low loss high frequency structure, as a result low loss may be obtained because of the signal propagation within air. Such a shielding of peripheral walls delimiting the low loss high frequency structure by conductive material may be realized as a continuous metallic lining of the sidewalls or by a metallic fence formed by a plurality of parallel electrically conductive posts, pillars and / or vias. In particular, two opposed sidewalls of the low loss high frequency structure may comprise said shielding or conductive material. Each sidewall can be replaced by a via fence. However, a metallized sidewall may have even a better shielding function than a via fence.

[0024] In an embodiment, said antenna is a slot antenna. However, the antenna can be any type of planar antenna, for instance a patch antenna as described below. For coupling the signal into and / or out of the waveguide, a slot may be formed on the waveguide. Such a slot is not necessarily an antenna, however it can be an antenna. A slot antenna may be formed as a structured metal surface, preferably a metal foil or a deposited metal layer of the stack, with one or more slot-shaped openings formed therein, wherein the structured metal may delimit the boundaries of a slot antenna. When this structured metal layer is driven as an antenna by an applied radio frequency signal, the slot radiates electromagnetic waves in a way similar to a dipole antenna. The shape and size of the one or more slots, as well as the driving frequency, determine the radiation pattern. Integrating a slot antenna into a laminated layer stack is a perfect match, since the planar characteristic of the slot antenna and the planar characteristic of the stack correspond to each other. The slot antenna may be embodied as an electrically conductive antenna structure on at least one of the at least one electrically insulating layer structure. An aperture in an electrically conductive layer structure above a topsided opening of the conductive shielding aperture may be opened to the external side of the stack. Such a slot-shaped (for instance oblong) aperture may be configured to contribute to a slot antenna configuration of said antenna. More specifically, the aperture may be formed as an oblong slot in an electrically conductive layer structure to thereby form a slot antenna. In this context, said aperture may additionally contribute to the slot antenna function.

[0025] In another embodiment, said antenna is a dielectric resonator antenna (DRA). Such a dielectric resonator antenna may be a radio antenna (which may be used for example at microwave frequencies and higher) which may comprise a block of a dielectric material (such as a ceramic material) of defined shape and a dielectric resonator mounted on a plane, for example a ground plane. A dielectric resonator antenna may comprise one or a plurality of blocks of dielectric material. Said dielectric material may be a low DK organic polymeric material or low DF organic polymeric material. Radio waves may be introduced into the inside of the resonator material from a transmitter and may excite appropriate electromagnetic modes. The walls of the resonator may be partially transparent to radio waves, allowing the radio power to radiate into a surrounding space. In particular, dielectric resonator antennas may lack metal parts (which may become lossy at high frequencies). Consequently, dielectric resonator antennas can have low losses and may be highly efficient at high microwave and millimeter wave frequencies. Preferably, a dielectric resonator antenna may be made of a material having a high DK value, for example of at least 6 or at least 8, preferably at least 10.

[0026] In an embodiment, said antenna is a patch antenna. A patch antenna may denote an antenna with a low profile, which can be formed on a dielectric surface by patterning one or more electrically conductive layers. A patch antenna may be formed based on a planar (for instance rectangular, circular, triangular, or with any other geometry) patterned layer of metal. The options of component carrier technology are fully compatible with such a planar antenna type. Advantageously, a plurality of patch antenna structures may be stacked with electrically insulating material in between, thereby rendering it possible to form antenna structures that support multiple frequencies or multiple frequency bands.

[0027] In an embodiment, the patch antenna comprises an electrically conductive patch structure on at least one of the at least one electrically insulating layer structure. For example, the at least one patch antenna is provided at least partially in a further cavity forming the non-conductive low loss high frequency structure. For instance, said patch antenna may partially delimit such a further cavity. However, a patch structure may also be formed on top of the component carrier. Thus, the patch structure may form part of an exterior outline of the component carrier.

[0028] In an embodiment, the patch antenna comprises at least one further electrically conductive patch structure above said electrically conductive patch structure. For example, a plurality of patch structures are provided on top of each other as said antenna. Preferably, at least one upper patch structure is overlapping or is in flush with a bottom one. Different patch structures may be configured for supporting different frequencies or frequency bands, thereby enabling an increased bandwidth. Two, three or more patch structures may be vertically stacked for further refining the antenna functionality.

[0029] In an embodiment, the component carrier comprises one or more vertical through connections interconnecting said electrically conductive patch structure with said at least one further electrically conductive patch structure and extending through at least one of said at least one electrically insulating layer structure. Thus, an electrically conductive layer structure forming a patch structure may be connected with a further electrically conductive layer structure forming a further patch structure on top of it. Said electrically conductive layer structures may be mutually spaced by an electrically insulating layer structure, and the mentioned electrical connection may be accomplished by one or more vertical through connections, such as copper filled vias. The connection of said two electrically conductive layer structures by vertical through connections may prevent floating electric potentials. This may have an additional positive impact on signal loss and signal integrity of the patch antenna.

[0030] In an embodiment, said vertical through connections are arranged in a matrix pattern along rows and columns, for example equidistantly from each other. This may ensure highly homogeneous electromagnetic wave coupling properties over the entire extension of the matrix.

[0031] In an embodiment, said vertical through connections have the same size and / or shape. This may simplify manufacturability and may also contribute to homogeneous electromagnetic wave coupling properties over the entire extension of the matrix.

[0032] In an embodiment, at least part of the patch antenna is arranged in or on the non-conductive low loss high frequency structure. In particular, a patch structure may delimit at least part of an upper main surface of the non- conductive low loss high frequency structure, for instance when embodied as a second cavity. This may lead to a highly compact design. In an embodiment, the patch antenna comprises at least a portion of at least one of the electrically conductive layer structures of the stack. More specifically, the patch antenna may be structured as one electrically conductive layer. However, the patch antenna may additionally have a ground plane (which may be arranged on another layer below). In other words, the patch antenna may be integrally formed with the laminated layer stack of the component carrier. This keeps the component carrier small and the signal paths short, thereby contributing to low losses and high radio frequency performance.

[0033] In an embodiment, the component carrier comprises an array of at least two antennas being spaced with respect to each other in a horizontal plane and / or along a vertical direction. For example, the at least two antennas can be spaced in a direction along the x-axis, or in a direction along the y-axis, wherein the z-axis is the height of the component carrier (such as a PCB). The at least two antennas may share a common cavity, i.e. may be coupled both with the same waveguide-type cavity. This may allow to obtain high transmission intensity, signal transmission diversity, signal transmission redundancy and / or may support multiple radiofrequencies or radiofrequency ranges supported by the antenna array. All this may be achieved with small space consumption. It has been found that an array of a plurality of antennas may lead to a significantly lower amount of warpage than one big antenna. However, it may also be possible that different antennas of the array each have their own cavity and waveguide, rather than sharing a common cavity.

[0034] In an embodiment, the component carrier comprises a frequency filter structure in and / or on said stack. For example, said frequency filter structure may be arranged at a feedline below said cavity, at said cavity, and / or on top of said low loss high frequency structure. In particular, the filter structure may be realized by a specific configuration of the feedline, of the lower cavity and / or of the upper cavity. Descriptively speaking, it may be possible to adjust the geometry of the mentioned constituent(s) so that only waves of a certain frequency or frequency range can pass efficiently. By such a frequency filter, a target frequency or target frequency range may be precisely adjusted, which may lead to a highly accurate signal transmission. In combination with the antenna, it may be possible to achieve a filtering antenna (which may be denoted as filtenna).

[0035] In an embodiment, the antenna and the frequency filter structure may be integrated into one common structure, which may be denoted as a filtenna. To enhance the PCB performance by reducing impedance mismatch, size, losses, etc., the antenna and the frequency filter structure can be integrated so as to serve as a multi-function module that performs filtering and radiating functions.

[0036] In an embodiment, the conductive shielding has a coupling slot on a top extremity of said cavity (wherein the top extremity may be defined with respect to a stacking direction of the stack), said coupling slot being vertically associated with the antenna (provided on top of said coupling slot) and / or with the non-conductive low loss high frequency structure. In the context of the present application, the term "coupling slot" may particularly denote an opening or a hole (in particular a through hole) in the conductive shielding at a top side of the cavity. Said hole may extend through the total thickness of the electrically conductive material of the conductive shielding in stack thickness direction. In an example, the opening of the conductive shielding on the top extremity of the cavity may have a round and / or edged (for example polygonal) shape (in a cross sectional view of the component carrier). Descriptively speaking, the coupling slot may couple electromagnetic waves between cavity and non-conductive low loss high frequency structure in a defined and direct, hence low-loss, manner.

[0037] In an embodiment, one of the plurality of electrically conductive layer structures, which is provided above the coupling slot, and a neighbouring of the electrically conductive layer structures are connected with each other by at least one vertical through connection. In particular, they can be connected by a plurality of vertical through connections placed around the coupling slot. Thus, an electrically conductive layer structure forming a top portion of the conductive shielding may be connected with a further electrically conductive layer structure on top of it. Said conductive layer structures may be mutually spaced by an electrically insulating layer structure, and the mentioned electrical connection may be accomplished by one or more vertical through connections, such as copper filled (for example laser) vias. The connection of said two electrically conductive layer structures by vertical through connections may prevent floating electric potentials. This may have an additional positive impact on signal loss and signal integrity.

[0038] In an embodiment, a top portion of said conductive shielding, in particular a top portion of said conductive shielding in which the coupling slot is formed, is a freely hanging structure (see for instance Figure 1). The free hanging structure may have at least a portion that is free of contact with other layer structures on its top side and on its bottom side. At least one main surface, preferably both main surfaces, of the top portion of the conductive shielding may be free of contact with other layer structures. The coupling slot on the conductive shielding may be provided in a cantilever fashion between said cavity and said low loss high frequency structure. "Free of contact" by one surface of the conductive shielding may mean that air is directly in contact with this surface. It is however also possible that low DK and / or low DF material faces one surface of the conductive shielding.

[0039] In an embodiment, a top portion of said conductive shielding in which said coupling slot is formed has a supporting electrically insulating structure arranged on a top surface and / or on a bottom surface of said top portion of said conductive shielding and arranged around said coupling slot (see Figure 8 or Figure 14). Alternatively or additionally, a supporting electrically conductive structure may be provided on top of said conductive shielding or said supporting electrically insulating structure.

[0040] In an embodiment, the component carrier comprises a radiofrequency lens component being surface mounted on top of the stack. Rather than being integrated in the stack, the mentioned radio frequency lens component may be an SMD (surface mounted device) component. By taking this measure, emitted and / or received radio frequency waves may be focused. This may lead to an improved signal transmission by enhancing directivity. As an alternative to a surface mounted radio frequency lens component, another embodiment may also integrate a radiofrequency lens in the stack.

[0041] In an embodiment, the antenna is formed as part of said stack, for example at least partially at an exterior surface of the stack. Advantageously, the antenna may be integrally formed with the stack. Consequently, a simple manufacturing process may be combined with a highly efficient electromagnet- ic coupling and with a compact design integrating both waveguide as well as antenna in the stack. Exemplary embodiments may provide an all-in-one solution with waveguide cavity and antenna integrated in the same stack without a need to assemble different parts, thereby avoiding alignment issues.

[0042] However, in other embodiments, the antenna may be also embodied as a surface mounted device mounted on a top main surface of the stack. This may be appropriate for instance if the antenna is configured as dielectric resonator antenna (DRA), see for instance Figure 7.

[0043] In an embodiment, the conductive shielding has a further coupling slot on the top extremity of said cavity side by side with said coupling slot. Hence, multiple coupling slots may be arranged at the same vertical level.

[0044] In an embodiment, the conductive shielding comprises a feeding slot on a bottom extremity of said cavity (wherein the bottom extremity may be defined with respect to the stack direction). Such a feeding slot or a further opening may form or form part of a feedline structure for feeding an electromagnetic signal into the cavity for subsequent emission of radiofrequency waves by the antenna. Preferably, the feeding slot is opposed to the coupling slot on the top extremity. These two openings in the conductive shielding may functionally cooperate and / or may be geometrically aligned with each other. More generally, the openings may be aligned, misaligned, offset, and / or rotated with respect to each other.

[0045] In an embodiment, the electrically conductive layer structure at the bottom of the cavity comprises a feedline structure for coupling a signal into and / or out of the waveguide. Thereby, an electric transition between waveguide and stack metal may be accomplished.

[0046] In an embodiment, said coupling slot and said feeding slot have different sizes and / or shapes. By using size (for instance length and / or width) and / or shape (in particular outline) of coupling slot and / or feeding slot as design parameters, the electromagnetic wave coupling properties of the component carrier may be fine-tuned.

[0047] In an embodiment, said coupling slot and said feeding slot are arranged parallel to each other. When coupling slot and feeding slot are oblong slots, their longest extension directions may be parallel to each other. This may lead to a proper alignment between coupling slot and feeding slot and thus a proper performance. However, alternatively, coupling slot and feeding slot may be arranged in a mutually slanted way.

[0048] In an embodiment, a maximum width of at least one of the coupling slot and the feeding slot is not more than 12 mm, preferably not more than 9 mm. This may achieve compliance with the needs of radiofrequency waves in the gigahertz range.

[0049] In an embodiment, one of the at least one electrically insulating layer structure delimiting a top side of the low loss high frequency structure is a core, for example with a thickness in a range from 50 pm to 600 pm, in particular in a range from 100 pm to 300 pm. A core may be an electrically insulating layer structure of the component carrier such as a printed circuit board being made of fully cured dielectric material. For instance, such a core may be made of FR.4 material. A core may comprise cured resin (such as epoxy resin) and reinforcing particles (such as glass fibers). Arranging a core at a top side of the non-conductive low loss high frequency structure may ensure mechanical stability while complying with the requirements of electromagnetic wave transmission. With the mentioned range of thicknesses, a proper tradeoff between mechanical stability and compactness may be obtained.

[0050] In an embodiment, the component carrier comprises a venting hole fluidical ly coupling or contributing to a pressure coupling of said low loss high frequency structure with an environment external to the stack or with yet another cavity. In this context, fluidically coupling may mean establishing a gas communication between the low loss high-frequency structure and an exterior of the stack. Furthermore, pressure coupling may denote that pressure differences between the low loss high-frequency structure and an exterior of the stack may be balanced. When air expansion (for example during reflow) in the cavity and / or in the non-conductive low loss high frequency structure (which may be a further cavity) is an issue, an additional venting hole may be formed. This may prevent any damage of the component carrier due to interior overpressure. For example, a pressure communication between the cavity, the non-conductive low loss high frequency structure (which may be a further cavity) and an exterior of the component carrier may be enabled through coupling slot and venting hole, so that pressure differences can be balanced out without harming the component carrier.

[0051] In an embodiment, said venting hole is closed by a membrane. If an extra protection against corrosion and the entry of dirt into the cavity shall be provided, it may be possible to close coupling slot and venting hole by a flexible or elastic membrane. This may still allow pressure exchange.

[0052] In an embodiment, said low loss high frequency structure extends in a vertical direction over at least two electrically insulating layer structures of the stack (see for instance Figure 2). This may allow to extend the spatial expansion of the low loss high frequency structure in a vertical direction, which may be advantageous for further reducing losses and / or for adjusting certain radiofrequency wave coupling properties. Alternatively, said low loss high frequency structure may extend only over a single electrically insulating layer structure in a vertical direction (see for example Figure 1). The result is a highly compact design.

[0053] In an embodiment, a vertical extension of said low loss high frequency structure is smaller than a vertical extension of said cavity. Additionally or alternatively, a horizontal extension of said low loss high frequency structure may be larger than a horizontal extension of said cavity. Preferred may be a deeper and narrower cavity in combination with a wider and shallower further cavity (as a preferred embodiment of the non-conductive low loss high frequency structure).

[0054] In an embodiment, at least part of sidewalls of said low loss high frequency structure is lined with a metallization layer or is provided with a metal fence. In the context of the present application, the term "metal fence" may in particular denote an arrangement of vertically extending electrically conductive posts laterally surrounding at least part of the low loss high frequency structure to thereby suppress electromagnetic radiation losses via sidewalls of the cavity. A metallization layer may continuously cover a portion of the sidewalls or even the entire sidewalls.

[0055] In an embodiment, the cavity is filled with a medium. Preferably, said medium may be air, so that the cavity may be an air-filled waveguide. As an alternative to air, the cavity may be filled with a sponge, and / or a dielectric material (for example a low DK and / or low DF material). In an embodiment, the cavity is configured for a frequency of at least 60 GHz of even at least 75 GHz. For example, the cavity has a width of less than 5 mm and a height of less than 2.5 mm. In other embodiment, the cavity may be adjusted for other frequencies, for instance a frequency of at least 10 GHz or a frequency of at least 50 GHz. To put it shortly, the dimensions of the cavity may be defined by a desired frequency or frequency range of electromagnetic waves to be processed by the component carrier. On the other hand, the dimensions of the non-conductive low loss high-frequency structure (in particular when embodied as air cavity) may define the achievable loss reduction. While large dimensions of such a further cavity may be advantageous for efficient loss reduction, other considerations (such as mechanical stability of the component carrier and a compact design) may limit the further cavity's dimensions.

[0056] In an embodiment, the component carrier comprises a stack of at least one electrically insulating layer structure and at least one electrically conductive layer structure. For example, the component carrier may be a laminate of the mentioned electrically insulating layer structure(s) and electrically conductive layer structure(s), in particular formed by applying mechanical pressure and / or thermal energy. The mentioned stack may provide a plate-shaped component carrier capable of providing a large mounting surface for further components and being nevertheless very thin and compact.

[0057] In an embodiment, the component carrier is shaped as a plate. This contributes to the compact design, wherein the component carrier nevertheless provides a large basis for mounting components thereon. Furthermore, in particular a naked die as example for an embedded electronic component, can be conveniently embedded, thanks to its small thickness, into a thin plate such as a printed circuit board.

[0058] In an embodiment, the component carrier is configured as one of the group consisting of a printed circuit board, a substrate (in particular an IC substrate), and an interposer.

[0059] In the context of the present application, the term "printed circuit board" (PCB) may particularly denote a plate-shaped component carrier which is formed by laminating several electrically conductive layer structures with several electrically insulating layer structures, for instance by applying pressure and / or by the supply of thermal energy. As preferred materials for PCB technology, the electrically conductive layer structures are made of copper, whereas the electrically insulating layer structures may comprise resin and / or glass fibers, so-called prepreg or FR.4 material. The various electrically conductive layer structures may be connected to one another in a desired way by forming holes through the laminate, for instance by laser drilling or mechanical drilling, and by partially or fully filling them with electrically conductive material (in particular copper), thereby forming vias or any other through-hole connections. The filled hole either connects the whole stack, (through-hole connections extending through several layers or the entire stack), or the filled hole connects at least two electrically conductive layers, called via. Similarly, optical interconnections can be formed through individual layers of the stack in order to receive an electro-optical circuit board (EOCB). Apart from one or more components which may be embedded in a printed circuit board, a printed circuit board is usually configured for accommodating one or more components on one or both opposing surfaces of the plateshaped printed circuit board. They may be connected to the respective main surface by soldering. A dielectric part of a PCB may be composed of resin with reinforcing fibers (such as glass fibers).

[0060] In the context of the present application, the term "substrate" may particularly denote a small component carrier. A substrate may be a, in relation to a PCB, comparably small component carrier onto which one or more components may be mounted and that may act as a connection medium between one or more chip(s) and a further PCB. For instance, a substrate may have substantially the same size as a component (in particular an electronic component) to be mounted thereon (for instance in case of a Chip Scale Package (CSP)). More specifically, a substrate can be understood as a carrier for electrical connections or electrical networks as well as component carrier comparable to a printed circuit board (PCB), however with a considerably higher density of laterally and / or vertically arranged connections. Lateral connections are for example conductive paths, whereas vertical connections may be for example drill holes. These lateral and / or vertical connections are arranged within the substrate and can be used to provide electrical, thermal and / or mechanical connections of housed components or unhoused components (such as bare dies), particularly of IC chips, with a printed circuit board or intermediate printed circuit board. Thus, the term "substrate" also includes "IC substrates". A dielectric part of a substrate may be composed of resin with reinforcing particles (such as reinforcing spheres, in particular glass spheres).

[0061] The substrate or interposer may comprise or consist of at least a layer of glass, silicon (Si) and / or a photoimageable or dry-etchable organic material like epoxy-based build-up material (such as epoxy-based build-up film) or polymer compounds (which may or may not include photo- and / or thermosensitive molecules) like polyimide or polybenzoxazole.

[0062] In an embodiment, the at least one electrically insulating layer structure comprises at least one of the group consisting of a resin or a polymer, such as epoxy resin, cyanate ester resin, benzocyclobutene resin, bismaleimide- triazine resin, polyphenylene derivate (for example based on polyphe- nylenether, PPE), polyimide (PI), polyamide (PA), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE) and / or a combination thereof. Reinforcing structures such as webs, fibers, spheres or other kinds of filler particles, for example made of glass (multilayer glass) in order to form a composite, could be used as well. A semi-cured resin in combination with a reinforcing agent, for example fibers impregnated with the above-mentioned resins is called prepreg. These prepregs are often named after their properties for example FR4 or FR5, which describe their flame retardant properties. Although prepreg particularly FR4 are usually preferred for rigid PCBs, other materials, in particular epoxy-based build-up materials (such as build-up films) or photoimageable dielectric materials, may be used as well. For high frequency applications, high-frequency materials such as polytetrafluoroethylene, liquid crystal polymer and / or cyanate ester resins, may be preferred. Besides these polymers, low temperature cofired ceramics (LTCC) or other low, very low or ultra-low DK materials may be applied in the component carrier as electrically insulating structures.

[0063] In an embodiment, the at least one electrically conductive layer structure comprises at least one of the group consisting of copper, aluminum, nickel, silver, gold, palladium, tungsten and magnesium. Although copper is usually preferred, other materials or coated versions thereof are possible as well, in particular coated with supra-conductive material or conductive polymers, such as graphene or poly(3,4-ethylenedioxythiophene) (PEDOT), respectively.

[0064] The at least one component can be selected from a group consisting of an electrically non-conductive inlay, an electrically conductive inlay (such as a metal inlay, preferably comprising copper or aluminum), a heat transfer unit (for example a heat pipe), a light guiding element (for example an optical waveguide or a light conductor connection), an electronic component, or combinations thereof. An inlay can be for instance a metal block, with or without an insulating material coating (IMS-inlay), which could be either embedded or surface mounted for the purpose of facilitating heat dissipation. Suitable materials are defined according to their thermal conductivity, which should be at least 2 W / mK. Such materials are often based, but not limited to metals, metal-oxides and / or ceramics as for instance copper, aluminium oxide (AI2O3) or aluminum nitride (AIN). In order to increase the heat exchange capacity, other geometries with increased surface area are frequently used as well. Furthermore, a component can be an active electronic component (having at least one p-n-junction implemented), a passive electronic component such as a resistor, an inductance, or capacitor, an electronic chip, a storage device (for instance a DRAM or another data memory), a filter, an integrated circuit (such as field-programmable gate array (FPGA), programmable array logic (PAL), generic array logic (GAL) and complex programmable logic devices (CPLDs)), a signal processing component, a power management component (such as a field-effect transistor (FET), metal-oxide-semiconductor field-effect transistor (MOSFET), complementary metal-oxide-semiconductor (CMOS), junction field-effect transistor (JFET), or insulated-gate field-effect transistor (IGFET), all based on semiconductor materials such as silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide (GazOs), indium gallium arsenide (InGaAs) and / or any other suitable inorganic compound), an optoelectronic interface element, a light emitting diode, a photocoupler, a voltage converter (for example a DC / DC converter or an AC / DC converter), a cryptographic component, a transmitter and / or receiver, an electromechanical transducer, a sensor, an actuator, a microelectromechanical system (MEMS), a microprocessor, a capacitor, a resistor, an induct- ance, a battery, a switch, a camera, an antenna, a logic chip, and an energy harvesting unit. However, other components may be embedded in the component carrier. For example, a magnetic element can be used as a component. Such a magnetic element may be a permanent magnetic element (such as a ferromagnetic element, an antiferromagnetic element, a multiferroic element or a ferrimagnetic element, for instance a ferrite core) or may be a paramagnetic element. However, the component may also be an IC substrate, an interposer or a further component carrier, for example in a board-in-board configuration. The component may be surface mounted on the component carrier and / or may be embedded in an interior thereof. Moreover, also other components, in particular those which generate and emit electromagnetic radiation and / or are sensitive with regard to electromagnetic radiation propagating from an environment, may be used as component.

[0065] In an embodiment, the component carrier is a laminate-type component carrier. In such an embodiment, the component carrier is a compound of multiple layer structures which are stacked and connected together by applying a pressing force and / or heat.

[0066] After processing interior layer structures of the component carrier, it is possible to cover (in particular by lamination) one or both opposing main surfaces of the processed layer structures symmetrically or asymmetrically with one or more further electrically insulating layer structures and / or electrically conductive layer structures. In other words, a build-up may be continued until a desired number of layers is obtained.

[0067] After having completed formation of a stack of electrically insulating layer structures and electrically conductive layer structures, it is possible to proceed with a surface treatment of the obtained layers structures or component carrier.

[0068] In particular, an electrically insulating solder resist may be applied to one or both opposing main surfaces of the layer stack or component carrier in terms of surface treatment. For instance, it is possible to form such a solder resist on an entire main surface and to subsequently pattern the layer of solder resist so as to expose one or more electrically conductive surface portions which shall be used for electrically coupling the component carrier to an electronic periphery. The surface portions of the component carrier remain- ing covered with solder resist may be efficiently protected against oxidation or corrosion, in particular surface portions containing copper.

[0069] It is also possible to apply a surface finish selectively to exposed electrically conductive surface portions of the component carrier in terms of surface treatment. Such a surface finish may be an electrically conductive cover material on exposed electrically conductive layer structures (such as pads, conductive tracks, etc., in particular comprising or consisting of copper) on a surface of a component carrier. If such exposed electrically conductive layer structures are left unprotected, then the exposed electrically conductive component carrier material (in particular copper) might oxidize, making the component carrier less reliable. A surface finish may then be formed for instance as an interface between a surface mounted component and the component carrier. The surface finish has the function to protect the exposed electrically conductive layer structures (in particular copper circuitry) and enable a joining process with one or more components, for instance by soldering. Examples for appropriate materials for a surface finish are Organic Solderability Preservative (OSP), Electroless Nickel Immersion Gold (ENIG), Electroless Nickel Immersion Palladium Immersion Gold (ENIPIG), gold (in particular hard gold), chemical tin, nickel-gold, nickel-palladium, etc.

[0070] The aspects defined above and further aspects of the invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to these examples of embodiment.

[0071] Figure 1 illustrates a cross-sectional view of a component carrier according to an exemplary embodiment of the invention.

[0072] Figure 2 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0073] Figure 3 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0074] Figure 4 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0075] Figure 5 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0076] Figure 6 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0077] Figure 7 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0078] Figure 8 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0079] Figure 9 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0080] Figure 10 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0081] Figure 11 illustrates a plan view of a component carrier according to an exemplary embodiment of the invention.

[0082] Figure 12 illustrates a plan view of a component carrier according to another exemplary embodiment of the invention.

[0083] Figure 13 illustrates a plan view of a component carrier according to another exemplary embodiment of the invention.

[0084] Figure 14 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0085] Figure 15 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0086] Figure 16 illustrates a cross-sectional view of a component carrier according to another exemplary embodiment of the invention.

[0087] The illustrations in the drawings are schematic. In different drawings, similar or identical elements are provided with the same reference signs.

[0088] Before referring to the drawings, exemplary embodiments will be described in further detail, some basic considerations will be summarized based on which exemplary embodiments of the invention have been developed.

[0089] Moving towards higher frequencies requires solutions for an improved loss performance and smaller structures preferably on PCB level. However, conventional approaches are mainly based on molded polymer-based antennas (for example gap waves) which are subsequently metalized. These antennas are assembled onto a PCB and require assembling technologies as well as interconnect-technologies accordingly. According to an exemplary embodiment, a component carrier (for example a printed circuit board, PCB) can be formed on the basis of a laminated layer stack, i.e. a stack of layer structures connected by pressure and / or heat. A cavity may be formed as a hollow volume in the stack which is delimited by peripheral walls (which may include sidewalls as well as bottom and top walls). Said peripheral walls may be lined partially by an electrically conductive shielding for enhancing electromagnetic wave transmission. On a top-side of the shielding, a top-sided non-conductive low-loss high-frequency structure (preferably a further separate cavity, for instance a further air cavity being wider in said lateral direction than said cavity) may be provided. An antenna may be arranged, in turn, above the non-conductive low loss high frequency structure. Such a component carrier may be manufactured with low effort and may show advantageous properties in terms of electromagnetic coupling. Further advantages, such as a high-bandwidth, a well-defined directivity and / or a high radiation efficiency may be achieved as well. Thus, a component carrier with excellent high-frequency properties may be obtained. In particular the additional non-conductive low loss high-frequency structure may have an impact on a better quality factor giving a higher antenna gain.

[0090] According to an exemplary embodiment, a component carrier with a sophisticated stack-up can be provided which is particularly appropriate for use in combination with an electronic component (such as a semiconductor die) which may be embedded in the stack in order to further improve the overall R.F systems performance. Such an electronic component may be configured for generating and / or processing high frequency signals. Moreover, it may be possible to add more functionalities to the stack, such as a filtering antenna. Advantageously, exemplary embodiments may combine different technologies with an embedded waveguide to achieve an excellent overall R.F performance. This may allow to achieve an improved overall R.F system performance in particular for millimeter-wave applications and higher frequencies. Thus, an improved or even optimized R.F performance may be achieved in combination with different types of antenna for higher gain, directivity and added functionality such as filtering and low loss feeding.

[0091] Exemplary embodiments may provide antennas, and in particular filtering antennas (which may be denoted as filtennas), in PCB technology. Different antenna technologies (such as a patch antenna, a horn antenna, a DRA antenna, a slot antenna, and optionally a high-frequency radiation lens) can be used on PCB level with very low loss feeding by utilizing an embedded air filled waveguide in the PCB. For additional size reduction and further performance improvement, an RFIC (radiofrequency integrated circuit) can be embedded in the stack. Antenna arrays composed of multiple antennas may be implemented as well to further refine the radiofrequency functionality (for instance a supported frequency range or different supported frequency ranges). In particular, one or more high gain antennas and / or filtennas of any of the above mentioned types may be integrated with or embedded in an airfilled waveguide formed in PCB technology. An air-filled waveguide can be itself a filter, and by using an antenna on top it may be possible to create a filtenna.

[0092] Exemplary embodiments may promote high gain antennas fed by low loss feedlines to improve or even optimize the overall performance of an RF system with added functionality such as filtering antennas. The antennas (in particular filtennas) may be fed by an embedded air-filled waveguide which may allow for a very low loss feeding. The RF signal may be fed to an embedded air-filled waveguide by an open slot in the waveguide. For example, the signal can be carried from a surface mounted device-type integrated circuit (SMD IC), an embedded integrated circuit (IC), and / or by one or more external connectors. On the other side of the embedded air-filled waveguide, the RF signal may be fed to the antenna also by an open slot (such as a coupling slot to the antenna layers). Advantageously, filtering functionality can be implemented by arranging vias (or other vertical through connections) between the coupling slot to the antenna structure. In order to reduce the losses from the filtering antenna, part of the dielectric material can be removed which may result in an air cavity below the antenna. The one or more antennas can be implemented for example as patch antennas, slot antennas, DRA antennas and / or horn antennas. The one or more antennas can be implemented in the PCB, more specifically may be integrated in the PCB stack. When even higher directivity is desired, a radiofrequency lens can be implemented (for example attached as a separate component) on the antenna. Moreover, a DRA can be attached instead of another antennas type, which may result in a higher bandwidth. A corresponding concept of removing the dielectric material can be used to implement an air cavity backed patch antenna. This may increase the gain of the antenna. Furthermore, all mentioned concepts can be used also for designing and implementing antenna arrays.

[0093] In an embodiment, it may be possible to insert a low DK material or a polymer in the cavity and / or the further cavity for providing a higher bandwidth. Alternatively, the cavity and / or the further cavity may also be an air cavity.

[0094] According to a preferred embodiment, a component carrier is provided which comprises a stack having at least two electrically conductive layer structures and at least one electrically insulating layer structure. A cavity (which may be configured as a waveguide) may be formed inside the stack. A signal modifier unit (for instance a further air cavity or a structure made of a low DK material) may be provided as well, which may form a non-conductive low loss high-frequency structure. Moreover, the component carrier may comprise an antenna. Advantageously, the signal modifier may be located between and / or may be associated to the cavity and the antenna. Additionally, the component carrier may comprise one or more further components, for example one or more semiconductor based components, such as a processor and / or a memory.

[0095] Advantageously, said antenna may be located on a surface area of the stack. Alternatively, at least part of the antenna may be embedded. A coupling slot may be located between the cavity and the signal modifier unit. Preferably, the coupling slot may physically connect the cavity and the signal modifier and / or may be configured to transmit radio frequency waves, for example with a frequency above 50 GHz. At least two coupling slots (for instance arranged above each other or arranged side-by-side) may be provided in an embodiment. For example, a feeding slot may be located on the bottom side of the cavity. Alternatively, the feeding slot may be located on a peripheral wall of the cavity or on the top side of the cavity. In an embodiment, the feeding slot and the one or more coupling slots may have a different size and / or shape. Additionally or alternatively, the feeding slot and at least one coupling slot may have similar, in particular the same, shape. For instance, the feeding slot and the one or more coupling slots may be arranged parallel to each other. In a further embodiment, the feeding slot and the one or more coupling slots may be located in a misaligned manner. The air cavity may be broader than an antenna patch (for instance made of copper). Alternatively, the air cavity may be narrower. A maximum width may only be limited by a manufacturing process and / or by a requirement concerning miniaturization. In one embodiment, the maximum width may be 7 mm, in order to reliably suppress warpage. A top-sided insulating layer of the stack, which may be in direct contact with the air cavity, may be a core for stability reasons (wherein such a core may preferably have a thickness in a range from 100 pm to 300 pm). Alternatively, the top-sided insulating layer of the stack, which may be in direct contact with the air cavity, may be a layer comprising or consisting of glass, for example a glass core, and / or ceramic material. For instance, the air cavity may have a venting hole. Optionally, said venting hole may be covered by a membrane for enabling pressure exchange. Between air cavity and waveguide, an additional electrically insulating layer (for example providing a coupling hole extending through the additional electrically insulating layer) may be provided. The air cavity may be so thick that it extends over at least two electrically insulating layer structures. Such a design may have an impact leading to a better quality factor giving, in turn, a higher antenna gain. For instance, the air cavity may be broader in width than the waveguide. Alternatively, the air cavity may have the same size or may be smaller than the waveguide. Adjusting the width of the antenna patch in relation to the thickness in stacking direction of the air cavity may be advantageously done to achieve a better quality factor when having a thicker air cavity. For example, the thickness of the air cavity, in particular the signal modifier unit, may be smaller than the thickness of the waveguide.

[0096] Alternatively, the thickness of the waveguide may be the same or smaller than the thickness of the air cavity, in particular the signal modifier unit. In a top view, the waveguide and the air cavity may have the same elongation direction (i.e. may extend parallel to each other), alternatively they may be mutually inclined. The antenna structure may comprise at least one copper patch, for example at least two copper patches. A via connection may be established between a copper layer over the air cavity and a further copper layer, which may create a higher gain, a better efficiency and / or a higher bandwidth. As an alternative, a copper block may be inserted which may extend over a vertical range of at least one thickness of one insulating layer structure. Advantageously, the aforementioned vias may create an m, n matrix with m rows and n columns (preferably equally distanced from each other). Preferably, said vias may have the same geometrical extension (such as diameter or shape). Alternatively, the vias may have different geometrical extensions (such as diameter or shape). In an embodiment, the vias are not directly located at the copper patch edge. For instance, copper patches may overlap (which may be preferred), but do not have to. In particular, different copper patches do not have to have the same size. For example, the copper patches may be arranged from thin to broad (for example from the center of the stack to the exposed surface). This may bring a higher directivity and / or bandwidth. In an embodiment, sidewalls of the air cavity may be metallized so that they act as a filter element. Alternatively, a via fence may be installed to provide a filter effect. Alternatively, the waveguide can be designed in a way to provide a filtering functionality. In an embodiment, a DRA antenna may be provided which may allow to achieve an even higher bandwidth. A lens may be provided for higher directivity. A surface mounted device, such as the above- mentioned lens and / or the above mentioned DRA antenna, may be connected (and optionally electrically coupled) with the stack by a connection structure (such as a sinter structure, a solder structure, etc., not shown in the figures). In one embodiment, a component carrier may comprise, in addition to its stack and / or integrated in the stack, the following building bricks: a waveguide, an additional air cavity, an antenna, a filter, and a lens.

[0097] Exemplary embodiments may allow for a direct feeding out of an airfilled substrate integrated waveguide (AFSIW), so that no losses may occur due to no transition. Furthermore, component carriers according to exemplary embodiments may show a high mechanical reliability, a low loss performance, and / or a small form factor. Exemplary embodiments may furthermore be compatible and scalable with or for millimeter-wave devices. Apart from this, component carriers according to exemplary embodiments of the invention are compatible with embedded components, surface mounted devices and IC substrates. Exemplary applications of exemplary embodiments of the invention are millimeter-wave devices, for example operating at or above 77 GHz, or even at or above 140 GHz. For instance, such component carriers may be configured for 5G or 6G applications, communication infrastructure, radar applications (for instance automotive radar applications, gesture radar applications), etc. Other advantageous applications of exemplary embodiments may be component carriers with sensing functionality and / or motion detection functionality. When operating in the lower millimeter-wave spectrum, the waveguide-type cavity of the component carrier of an exemplary embodiment of the invention can be implemented in half-mode. A specific application of a component carrier according to an exemplary embodiment is a 77 GHz hollow waveguide-fed slot antenna for an automotive radar device. Exemplary embodiments may operate in the sub-terahertz range.

[0098] Figure 1 illustrates a cross-sectional view of a component carrier 100 according to an exemplary embodiment of the invention. In the shown embodiment, component carrier 100 is embodied as a printed circuit board (PCB). However, component carrier 100 may also be an integrated circuit (IC) substrate, etc.

[0099] Component carrier 100 according to Figure 1 comprises a laminated layer stack 102 comprising a plurality of electrically conductive layer structures 150 and of electrically insulating layer structures 152. The electrically conductive layer structures 150 may comprise patterned copper layers which may form horizontal antenna structures, horizontal shielding structures, horizontal pads and / or a horizontal wiring structures. Additionally, the electrically conductive layer structures 150 may comprise vertical through connections (not shown in Figure 1) such as copper pillars and / or copper filled laser vias. Additionally or alternatively, mechanical plated through holes (PTH) may also be used as vertical through connections. Moreover, the stack 102 of the component carrier 100 may comprise one or more electrically insulating layer structures 152 (such as one or more prepreg sheets, resin sheets or cores made of FR4). Ajinomoto Build-Up Film ® (ABF) materials are also possible for at least part of the electrically insulating layer structures 152, in particular when the component carrier 100 is embodied as an IC substrate. Also surface finish (like ENIG or ENEPIG, a solder resist, etc.) may be optionally applied on the top side and / or on the bottom side of the stack 102 (not shown).

[0100] For example, each of the electrically conductive layer structures 150, which may be embodied as copper layers, may have a thickness in a range from 5 pm to 350 pm, for example in a range from 20 pm to 30 pm. Some of the electrically insulating layer structures 152 may be prepreg layers with a thickness in a range from 20 pm to 300 pm, for example in a range from 60 pm to 100 pm. Other ones of the electrically insulating layer structures 152 may be core layers made of FR.4 with a thickness in a range from 50 pm to 1000 pm, for example in a range from 150 pm to 400 pm. Additionally or alternatively, the electrically insulating layer structure 152 may comprise a layer comprising or consisting of glass, for example a glass core, and / or ceramic material, for example with a thickness in a range from 20 pm to 400 pm, respectively.

[0101] Moreover, a cavity 104 is formed as an air-filled hollow volume in the stack 102. In the shown embodiment, the cavity 104 is filled with air. Hence, an air-filled waveguide structure integrated in stack 102 may be provided according to Figure 1. Alternatively, another medium may be filled into waveguide cavity 104, for instance, a dielectric solid and / or sponge medium and / or gel. The cavity 104 may be delimited from the stack 102 by a peripheral wall, which may include a circumferentially closed sidewall as well as a bottom wall and a top wall. An electrically conductive shielding 106, for example a copper coating or a coating made of another metallic material, may cover a major portion of the peripheral wall of the cavity 104. The electrically conductive shielding 106 may comprise at least one, in particular at least two, layers of metallic material. The at least one layer of the metallic material may comprise metal, in particular copper or titanium. In a preferred embodiment, the at least two layers of metallic material may comprise the same material, for example copper. In a further embodiment, the at least two layers of metallic material may comprise at least two different metals, for example titanium and / or copper and / or tungsten and / or molybdenum and / or tantalum. In another embodiment, at least one of the at least two layers of metallic material may comprise metallic compounds, for example metal salts, in particular metal oxides and / or metal nitrides, for example copper oxide and / or titanium oxide and / or titanium nitride. More specifically, the electrically conductive shielding 106 may cover the entire peripheral wall with the exception of a bottom-sided feeding slot 132 and a top-sided coupling slot 110. Preferably, more than 50%, in particular more than 70%, of the surface area of the cavity 104 may be in direct contact with or may be covered by the electrically conductive shielding 106. Optionally, the electrically conductive shielding 106 may have a roughness Rz and / or Ra smaller than 2 pm, in particular smaller than 900 nm, more particularly smaller than 600 nm. In some embodiments, when easy manufacturing is preferred, vias fence can be used as electrically conductive shielding 106.

[0102] The cavity 104 with its metallic lining according to reference sign 106 may form an air-filled waveguide constituting a Faraday cage for electromagnetic radiofrequency waves. Advantageously, said waveguide-type cavity 104 being integrated in the stack 102 leads to a compact design and a high-power handling capability. At the top or bottom closure of the cavity (i.e. the lid), the dielectric material layer can be non-reflow prepreg.

[0103] Furthermore, an antenna 108 (or antenna structure) is provided which is integrated in the stack 102 according to Figure 1. This further promotes the compact design of component carrier 100.

[0104] In Figure 1, the antenna 108 is configured as a patch antenna 108" being defined by the uppermost of the electrically conductive layer structures 150 which is a patterned copper layer providing a patch structure 156. Still referring to Figure 1, it can be seen that the conductive shielding 106 has coupling slot 110 on a top extremity of said cavity 104 along a stack direction 112. Said coupling slot 110 is vertically associated with the antenna 108 provided above said coupling slot 110 vertically separated by a non-conductive low loss high frequency structure 154. In the embodiment of Figure 1, the non-conductive low loss high frequency structure 154 is configured as a further air-filled cavity arranged above and in gas communication with airfilled cavity 104.

[0105] During operation of component carrier 100 of Figure 1, a high-frequency signal (for instance having a frequency of 10 GHz or more, for instance 77 GHz) may be coupled into cavity 104 via a feeding structure which is here embodied as a feedline 160 forming part of the electrically conductive layer structures 150 and being arranged at or below a bottom wall of the cavity 104. As shown as well in Figure 1, the conductive shielding 106 comprises feeding slot 132 on a bottom extremity of said cavity 104 along the stack direction 112 and relating to said feeding structure which is here embodied as feedline 160. Adjacent to the feeding slot 132, the above-described feedline 160 is formed for coupling an electromagnetic wave into the waveguide-type cavity 104. To put it shortly, the electromagnetic signal is fed into cavity 104 at the bottom of the waveguide via the feedline 160. The high-frequency signal coupled into cavity 104 may for instance be generated by at least one electronic component (not shown in Figure 1, see reference sign 170 in Figure 3), such as one or more semiconductor chips, which may be embedded in an interior of the stack 102 and / or surface mounted on top of the stack 102. Such a semiconductor chip may also be mounted on a substrate, which may form the stack 102 or which may be provided in addition to stack 102. After being coupled from feedline 160 into cavity 104, the electromagnetic signal may be applied to antenna 108 for wireless transmission towards an environment of component carrier 100. Preferably, the high frequency signal may be coupled from feedline 160 into the cavity 104, from cavity 104 via coupling slot 110 into the non-conductive low loss high frequency structure 154 and from non- conductive low loss high frequency structure 154 into antenna 108.

[0106] Alternatively, a high-frequency signal propagating in the environment of component carrier 100 may be captured by antenna 108, may be coupled into cavity 104 and may be further conveyed to electrically conductive layer structures at the bottom of the cavity 104 and from there towards an intended destination (such as an electronic component like a semiconductor chip, see reference sign 170 in Figure 3) for further processing.

[0107] Thus, component carrier 100 can be configured as a radiofrequency transmitter, a radiofrequency receiver or a radio frequency transceiver (i.e. combined transmitter and receiver). It is also possible to provide a plurality of cavity-low loss high frequency structure-antenna-configurations in one and the same stack 102, for instance arranged side-by-side and laterally spaced by stack material. As already mentioned, the non-conductive low loss high frequency structure 154 is arranged above said cavity 104, and said antenna 108 is arranged above said low loss high frequency structure 154. In the shown embodiment, the low loss high frequency structure 154 is formed as a further air-filled cavity above said air-filled cavity 104 with a bottleneck in form of the upper portion of conductive shielding 106 with coupling slot 110 in between. Hence, the low loss high-frequency structure 154 is vertically sandwiched between the cavity 104 and the antenna 108. As illustrated in Figure 1, the further cavity is closed on a top side by the uppermost electrically insulating layer structure 152 of stack 102.

[0108] As already mentioned, the antenna 108 of Figure 1 is a patch antenna 108" which is integrated in stack 102. The electrically conductive patch structure 156 of patch antenna 108" is formed on a top main surface of the uppermost electrically insulating layer structure 152 and may for example form part of an exterior surface of component carrier 100.

[0109] Again referring to Figure 1, a top portion of said conductive shielding 106 in which the coupling slot 110 is formed, is realized as a cantilever-type freely hanging structure. This keeps the amount of dielectric material in wave propagation direction small, thereby contributing to an excellent signal integrity and a low loss performance of component carrier 100. In an example, at least a portion of the top portion of said conductive shielding 106 may have a thickness in a range from 5 pm to 350 pm, in particular in a range from 30 pm to 200 pm.

[0110] The uppermost of the electrically insulating layer structures 152 which delimits a top side of the low loss high frequency structure 154 may be a core with a thickness D in a range from 100 pm to 300 pm, for instance of 200 pm. Additionally or alternatively, the electrically insulating layer structure 152 which delimits a top side of the low loss high frequency structure 154 may comprise a layer comprising or consisting of glass, for example a glass core, and / or ceramic material, for example with a thickness in a range from 20 pm to 400 pm, respectively. This may provide a reliable mechanical protection of the hollow component carrier 100. For instance, said core may be made of fully cured epoxy resin with reinforcing glass fibers therein. Preferably, the vertical walls of cavities according to reference signs 104 and 154 may be substantially parallel to the stack direction 112. Alternatively, the vertical walls or sidewalls may be inclined.

[0111] Still referring to Figure 1, a vertical extension h of said low loss high frequency structure 154 is smaller than a vertical extension H of said cavity 104. Alternatively, the vertical extension h of said low loss high frequency structure 154 is similar, in particular the same, or bigger than the vertical extension H of said cavity 104. However, a horizontal extension L of said low loss high frequency structure 154 can be larger than a horizontal extension I of said cavity 104. Alternatively, the horizontal extension L of said low loss high frequency structure 154 can be similar, in particular the same, or smaller than the horizontal extension I of said cavity 104. The dimensions of the cavity 104 may be adjusted in accordance with a frequency or a frequency range of electromagnetic waves propagating along component carrier 100 during operation. For example, the dimensions of the cavity 104 may be configured for a frequency in the gigahertz range, for example up to 27 GHz, or even at least 75 GHz. The dimensions of the non-conductive low loss high frequency structure 154, which is here embodied as a further hollow cavity, may be made sufficiently large for strongly reducing radiofrequency losses of radiofrequency waves propagating between feedline 160 and antenna 108 towards the exterior of component carrier 100. Descriptively speaking, the volume of the non-conductive low loss high frequency structure 154 substitutes ordinary prepreg or the like, the latter attenuating radiofrequency waves in a stronger way than the cavity-type low loss high-frequency structure 154.

[0112] The additional air cavity of Figure 1, i.e. non-conductive low loss high frequency structure 154, may improve a quality factor leading to a higher antenna gain. Said additional air cavity provides an improvement of antenna gain and / or efficiency by reducing dielectric material losses. The antenna 108 may be fed by feedline 160, which may for instance be a microstrip / SIW (substrate integrated waveguide) line. The R.F signal coupling to the air-filled waveguide may be accomplished via the feedline 160. The layer structures 150, 152 of stack 102 can be used for routing. Vias (not shown) can also be implemented in order to provide an efficient vertical coupling along a short path. Thus, the described embodiment provides an embedded waveguide implemented in a PCB and allows to achieve low loss transmission lines. Also possible is an implementation of a slotted waveguide antenna or another antenna type, as an alternative to the illustrated patch antenna 108". For example, a diameter of a patch antenna 108" may be in a range from 1 mm to 12 mm.

[0113] Figure 2 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0114] The embodiment of Figure 2 differs from the embodiment according to Figure 1 in particular in that, according to Figure 2, said low loss high frequency structure 154 extends in a vertical direction over two electrically insulating layer structures 152 and one electrically conductive layer structure 150 in between. By realizing a vertical extension of the non-conductive low loss high frequency structure 154, embodied again as an additional air-filled cavity, over a plurality of vertically stacked electrically insulating layer structures 152, the dimension (in particular vertical extension h) of the further cavity may be further increased. This may lead to an additional reduction of the R.F losses.

[0115] Figure 3 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0116] The embodiment of Figure 3 differs from the embodiment according to Figure 1 in particular in that, according to Figure 3, an electronic component 170 embodied as a radiofrequency semiconductor die is embedded in stack 102 beneath feedline 160. By some of the electrically conductive layer structures 150, including vertical through connections 130, the embedded electronic component 170 may be electrically coupled with feedline 160 at a bottom side of cavity 104. Although not shown in Figure 3, the feedline 160 and the vertical through connections 130 may be electrically coupled with each other by additional electrically conductive vertical through connections (such as vias) in between. The embedded electronic component 170 may generate radiofrequency signals which may be coupled via the feedline 160 into the cavity 104, from there to the non-conductive low loss high frequency structure 154, to antenna 108 and finally towards an environment of the component carrier 100. Additionally or alternatively, electronic component 170 may be configured for processing received high-frequency signals. Further additionally or alterna- lively, an electronic component may be surface mounted on the stack 102 (not shown) or may be mounted on a separate board. However, embedding electronic component 170 in stack 102 beneath cavity 104 and directly next to feedline 160 may lead to very short signal path, and may therefore contribute additionally to low losses. It may also be possible to position the electronic component 170 next to the cavity 104 (left or right, for example on the same level of the cavity 104). The shorter the distances, the lower the losses.

[0117] Furthermore, Figure 3 shows that sidewalls of said cavity-type low loss high frequency structure 154 is lined with a metallization layer 133 (or with a metal fence composed of circumferentially arranged electrically conductive vertical through connections, not shown). Such a sidewall metallization of the further cavity may further reduce radiofrequency losses. Preferably, the metallized sidewall of the further cavity (i.e. low loss high frequency structure 154) may be transversally shifted compared to the conductive shielding 106. Alternatively, the metallized sidewall of the further cavity (i.e. low loss high frequency structure 154) may be located such, that it will be on a straight line with the conductive shielding 106 regarding the stack direction 112. In an embodiment, the material of the metallization layer 133 may comprise copper. In a further example, the metallization layer 133 may comprise at least two layers. For example, said at least two layers comprise the same material, i.e. copper, or the at least two layers comprise different material, for instance copper and titanium.

[0118] Figure 4 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0119] The embodiment of Figure 4 differs from the embodiment according to Figure 2 in particular in that, according to Figure 4, an electronic component 170 embedded in stack 102 is shown (compare description of Figure 3).

[0120] Furthermore, the antenna 108 of Figure 4 is a slot antenna 108', rather than a patch antenna 108" as in the above-described embodiments. For forming slot antenna 108', the coupling slot 110 may define a lengthy slot with a length being larger than its width. An uppermost electrically conductive layer structure 150 may be patterned so as to have a large central opening aligned with coupling slot 110. For example, the length-to-width ratio of the coupling slot 110 of Figure 4 may be at least two, for example at least four. For exam- pie, the length of the coupling slot 110 may be in a range from 1 mm to 5 mm, for instance 2 mm. For instance, the width of the coupling slot 110 may be in a range from 100 pm to 1 mm, for instance 200 pm to 700 pm. The length and width direction are perpendicular to the stack direction 112 and are also perpendicular relative to each other. Formation of coupling slot 110 in the described way may allow to obtain a low loss of radiation. The slot antenna 108' design of Figure 4 may allow to reduce losses significantly. To put it shortly, the slot antenna 108' of Figure 4 is embodied as an opened copper layer with one or more oblong slots. A corresponding patterning of the uppermost electrically conductive layer structure 150 of Figure 4 may contribute to the functionality of slot antenna 108' as well.

[0121] Furthermore, the embodiment of Figure 4 comprises a venting hole 165 in the uppermost electrically insulating layer structure 152 accomplishing a pressure coupling of cavity 104 and coupled low loss high frequency structure 154 with an environment external of the stack 102. As shown, said venting hole 165 may be optionally closed by a membrane 166. Membrane 166 (preferably a flexible or elastic membrane) may cover the venting hole 165. This may protect the conductive shielding 106 lining cavity 104 against corrosive impact and the cavity 104 as well as the low loss high frequency structure 154 against the intrusion of dirt. At the same time, an elastic or flexible property of the membrane 166 may allow a pressure exchange between an interior and an exterior of the hollow volume formed by the cavity 104 and the low loss high frequency structure 154.

[0122] Figure 5 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0123] The embodiment of Figure 5 differs from the embodiment according to Figure 2 in particular in that, according to Figure 5, the patch antenna 108" comprises a further electrically conductive patch structure 156 above said electrically conductive patch structure 156.

[0124] In an embodiment, the electrically conductive patch structure 156 and the further electrically conductive patch structure 156 may have similar, in particular the same, size. Alternatively, the size of the electrically conductive patch structure 156 and the size of the further electrically conductive patch structure 156 may differ by at least 20%, in particular by at least 30%. For instance, the sizes may differ in a range from 1% to 30% or 40%, typically slightly smaller than by 10%.

[0125] An array of electrically conductive vertical through connections 130 interconnect said electrically conductive patch structure 156 with said further electrically conductive patch structure 156 and extend through the uppermost electrically insulating layer structure 152 in between. Said vertical through connections 130 may be arranged in a matrix pattern along rows and columns, for example equidistantly from each other. To obtain a symmetric configuration, said vertical through connections 130 may all have the same size and shape. Alternatively, the vertical through connections 130 may be arranged in a non-regular distribution, for example randomly, and / or may have different size and shape. The lower patch structure 156 of the patch antenna 108" is arranged in the further cavity defining the non-conductive low loss high frequency structure 154. Both patch structures 156, 156 are formed as parts of the electrically conductive layer structures 150 of the stack 102. The configuration of Figure 5 connecting planar patch structures 156, 156 arranged at different heights of stack 102 by electrically conductive vertical through connections 130 may provide a higher gain, and a better efficiency. The vias can provide a higher bandwidth. It may be advantageous that a lower patch structure 156 is thinner than an upper patch structure 156 for fine- tuning the high-frequency properties of component carrier 100.

[0126] Alternatively to Figure 5, it is also possible that the non-conductive low loss high frequency structure 154 extends vertically only over a single electrically insulating layer structure 152, for instance as in Figure 1. Furthermore, it is possible that an electronic component 170 is embedded in stack 102 beneath cavity 104, for example as in Figure 3.

[0127] Figure 6 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0128] The embodiment of Figure 6 differs from the embodiment according to Figure 5 in particular in that, according to Figure 6, three patch structures 156 are vertically stacked with a respective electrically insulating layer structure 152 in between two respectively adjacent patch structures 156. Vertical through connections 130 connect the two lowermost patch structures 156 and the two uppermost electrically conductive patch structures 156 with each other. While the embodiment of Figure 5 with its two electrically coupled patch antennas already provides improved bandwidth and improved efficiency, the embodiment of Figure 6 with three electrically coupled patch structures 156 may provide an even better bandwidth and efficiency. It may be advantageous that the lowermost patch structure 156 is thinner than the central patch structure 156, and that the central patch structure 156 is thinner than the uppermost patch structure 156 for fine-tuning the high-frequency properties of component carrier 100. There may be an even more pronounced effect when changing the pad size (length and width) in the horizontal plane (i.e. along x- axis and / or y-axis) perpendicular to the stack direction 112. In view of this, the patch sizes may be the same (as shown in Figure 6) or may be different.

[0129] Alternatively to Figure 6, it is also possible that the non-conductive low loss high frequency structure 154 extends vertically only over a single electrically insulating layer structure 152, for instance as in Figure 1. Furthermore, it is possible that an electronic component 170 is embedded in stack 102 beneath cavity 104, for example as in Figure 3.

[0130] Figure 7 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0131] The embodiment of Figure 7 differs from the embodiment according to Figure 1 in particular in that, according to Figure 7, the low loss high frequency structure 154 comprises a full layer of low DF material (such as Megtron 7 from Panasonic™, etc.) extending over an entire width of the stack 102. It is possible that the dielectric material of the low loss high frequency structure 154 of Figure 7 has a lower DF value than both directly neighboured electrically insulating layer structures 152, and preferably than all electrically insulating layer structures 152 of stack 102.

[0132] A further difference with regard to the embodiment of Figure 1 is that, according to Figure 7, said antenna 108 is a dielectric resonator antenna (DRA) 108"'. The dielectric resonator antenna 108"' is here embodied as a component being surface mounted on the top main surface of the stack 102 rather than being integrated in the stack 102. An adhesive layer 172 can be used for assembling the dielectric resonator antenna 108'" to the stack 102. The dielectric resonator antenna 108'" may have a high DK value of at least 8, for instance 10. The dielectric resonator antenna 108"' may be provided for higher bandwidth. The dielectric resonator antenna 108"' may be used as radiating element, which is based on dielectric material, preferably with a high DK value around 10. The dielectric resonator antenna 108'" may be assembled on the PCB and may be suitable for applications with frequencies of 27 GHz and higher. The dielectric resonator antenna 108'" may be fed by a feedline 160 embodied as a microstrip / SIW (substrate integrated waveguide).

[0133] Although not shown in Figure 7, it is possible that an electronic component 170 is embedded in stack 102 beneath cavity 104, for example as in Figure 3.

[0134] Although not shown in Figure 7, there may be vias between the layer under the dielectric resonator antenna 108'" and the waveguide.

[0135] Figure 8 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0136] The embodiment of Figure 8 differs from the embodiment according to Figure 7 in particular in that, according to Figure 8, a top portion of said conductive shielding 106 in which said coupling slot 110 is formed has a supporting electrically insulating structure 162 arranged on a top surface and arranged around said coupling slot 110.

[0137] Furthermore, Figure 8 realizes the non-conductive low loss high frequency structure 154 with a laterally confined structure of a low DF material inserted in a through hole of an electrically insulating layer structure 152. Preferably, the non-conductive low loss high frequency structure 154 may be located such in the electrically insulating layer structure 152, that the coupling slot 110 is in direct contact with the non-conductive low loss high frequency structure 154. Two slots above and below the non-conductive low loss high frequency structure 154 may be aligned. Any of the two slots may be air-filled or filled with a solid dielectric. In other words, contrary to the embodiment of Figure 7, the non-conductive low loss high frequency structure 154 of Figure 8 does not extend over the full width of the stack 102 but is embodied as an inlay in an electrically insulating layer structure 152 being made of low DF material. Alternatively, the non-conductive low loss high frequency structure 154 of Figure 8 can be an air cavity as in Figure 1.

[0138] Also in the embodiment of Figure 8, the antenna 108 is embodied as surface mounted dielectric resonator antenna 108"'. A radiofrequency signal inserted into the cavity 104 by feedline 160 may be generated by an embedded electronic component 170, as in Figure 3. However, such an R.FIC- type electronic component 170 may also be embodied as a surface mounted device.

[0139] Figure 9 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0140] The embodiment of Figure 9 differs from the embodiment according to Figure 5 in particular in that, according to Figure 9, a lens component 182 is provided being surface-mounted on the stack 102. Descriptively speaking, radio frequency lens component 182 may focus radiofrequency waves emitted by patch antenna 108" which is located directly below the lens component 182. The surface mounted lens component 182 may be attached to the upper main surface of the stack 102 by an adhesive layer 172.

[0141] Moreover, a frequency filter structure 158 is foreseen in an upper portion of said stack 102. Said frequency filter structure 158 may define a preferred frequency or frequency range of radiofrequency radiation to be emitted with high efficiency. In the embodiment of Figure 9, said frequency filter structure 158 is arranged on top of said low loss high frequency structure 154 integrated with antenna 108.

[0142] However, the filter structure 158 may be alternatively provided between the electronic component 170 and the cavity 104 or between the cavity 104 and the non-conductive low loss high frequency structure 154. Furthermore, the filter function may be provided regardless of whether or not the lens component 182 is foreseen.

[0143] The lens component 182 on top is provided for higher directivity. Plus, the lens component 182 can contribute to the antenna functionality. Such a lens component 182 can be integrated with an antenna 108 or can be added on top of an antenna 108 (which can also be another type of antenna than in Figure 9, for example a horn antenna, a slot antenna, etc.) to achieve higher gain and directivity.

[0144] As shown in Figure 9, the portion of the electrically conductive layer structure 150 forming part of an upper main surface of the further cavity-type non-conductive low loss high frequency structure 154 can be patterned. Although not shown, it can be alternatively a continuous metallic structure.

[0145] Figure 10 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0146] The embodiment of Figure 10 differs from the embodiment according to Figure 5 in particular in that, according to Figure 10, the patch antenna 108" of the type according to Figure 5 is combined with a surface mounted lens component 182.

[0147] Moreover, an embedded electronic component 170 for generating radiofrequency waves to be introduced in cavity 104 is foreseen in Figure 10 (however, it can also be omitted or substituted by a surface mounted electronic component 170).

[0148] Figure 11 illustrates a plan view of a component carrier 100 according to an exemplary embodiment of the invention. More precisely, Figure 11 is a top view of the component carrier 100 shown in a cross-sectional view in Figure 5. In particular, Figure 11 shows two vertically spaced patch structures 156, 156 being vertically interconnected by a matrix-like array of copper-filled vias forming vertical through connections 130. More specifically, the patch structures 156, 156 are realized as a top-sided copper patch and a further copper patch one layer below the top-sided copper patch. As shown, the patch structures 156, 156 may be mutually displaced within a horizontal plane and / or may have different dimensions within the horizontal plane.

[0149] Furthermore, Figure 11 illustrates that the conductive shielding 106 has a further coupling slot 110 on the top extremity of said cavity 104 side by side with said coupling slot 110. The coupling slots 110, 110 of Figure 11 are mutually slanted. They are also mutually slanted with respect to feeding slot 132 adjacent to feedline 160. Alternatively, said coupling slots 110 and said feeding slot 132 may be arranged parallel to each other.

[0150] Each coupling slot 110 may define a lengthy slot with a length L being larger than its width W. Preferably, a maximum width W of the coupling slot 110 and the feeding slot 132 is not more than 12 mm. This may suppress warpage. As shown, said coupling slots 110 and said feeding slot 132 may have different sizes and / or shapes.

[0151] The design parameters of the component carrier 100 can be as shown in Figure 11, or may be embodied in another way: The copper patches forming the patch structures 156 do not have to have the same size or shape (for instance, they may also be round). The air cavity forming the low loss high frequency structure 154 may also be smaller than the copper patches. The one or more coupling slots 110 may be located at least partially in the area of the copper patches. Metalized side walls or a via fence of the air cavity are optional but can reduce cross talk to other channel if applied.

[0152] In one embodiment, the feeding slot 132 may be located outside of the area of the patch structure 156. Alternatively, the feeding slot 132 may be located at least partially inside the area of the patch structure 156, which may be preferred.

[0153] Figure 12 illustrates a plan view of a component carrier 100 according to another exemplary embodiment of the invention.

[0154] The embodiment of Figure 12 differs from the embodiment according to Figure 11 in particular in that, according to Figure 12, one common cavity 104 spatially and functionally cooperates with two (or more) antennas 108, which are patch antennas 108" in the illustrated embodiment. For this purpose, cavity 104 overlaps, in the illustrated in view, with patch structures 156 of both patch antennas 108". Hence, an array of a plurality of antennas 108, 108 may be formed in and / or on one common stack 102 of a common component carrier 100. In the embodiment of Figure 12, the common cavity 104 has an elongate straight shape in the plan view of Figure 12. Optionally, the cavity 104 may comprise a filter structure 158.

[0155] Figure 13 illustrates a plan view of a component carrier 100 according to another exemplary embodiment of the invention.

[0156] The embodiment of Figure 13 differs from the embodiment according to Figure 12 in particular in that, according to Figure 13, the common cavity 104 serving both antennas 108 (again embodied as patch antennas 108") has a bifurcated geometry in the plan view of Figure 13. More specifically, the feeding slot 132 next to feedline 160 is arranged at a root portion 174 of cavity 104. Starting from root portion 174, cavity 104 is split up at a bifurcation portion 176 into a first branch 178 leading to a first antenna 108 and a second branch 179 leading to a second antenna 108.

[0157] In an embodiment, it may be possible to combine the feature of Figure 12 with Figure 13 so that one branch 178, 179 may be connected to a plurality of antennas 108 arranged in series.

[0158] Figure 14 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0159] According to Figure 14, antenna 108 is configured as patch antenna 108". More specifically, patch antenna 108" may also be denoted as an aperture coupled patch antenna. The patch antenna 108" of Figure 14 is provided above the coupling slot 110 in the conductive shielding 106 and above a further cavity constituting non-conductive low loss high frequency structure 154. Coupling slot 110 is vertically associated with the patch antenna 108", which is however provided on top of or above said coupling slot 110. The patch antenna 108" of Figure 14 has a planar extension area greater than a planar extension area of the coupling slot 110 in the conductive shielding 106 and smaller than a planar extension area of the non-conductive low loss high frequency structure 154.

[0160] The uppermost electrically insulating layer structure 152 closes the aperture defining non-conductive low loss high frequency structure 154 to thereby protect the conductive shielding 106 against corrosion or the like. The patch antenna 108" is formed as an uppermost patterned electrically conductive layer structure 150 of the stack 102. Descriptively speaking, the patch antenna 108" functions as radiator, whereas coupling slot 110 functions as coupler.

[0161] Moreover, Figure 14 illustrates a conductive connection medium 142 around a circumference of the cavity 104. In Figure 14, the conductive connection medium 142 is arranged around a circumference enclosing the top extremity of said cavity 104. Preferably, said conductive connection medium 142 is made of a solder structure, for example comprising tin and / or antimony and / or bismuth and / or silver and / or zinc, or a sinter structure, for example copper and / or silver and / or gold and / or oxides of the listed metals or combinations thereof. The conductive connection medium 142 should have a high electrical conductivity, in particular higher than 106S / m (at 20° C), so as to contribute to the shielding function of electrically conductive shielding 106. Below the conductive connection medium 142 and laterally adjacent to the conductive shielding 106, a dielectric structure 161 is arranged. Dielectric structure 161 may be made of a build-up dielectric (for example plugin paste with low coefficient of thermal expansion (CTE), but more generally it can be any material suitable to gain height, for example locally applied prepreg; also copper can be used as build-up material). The conductive connection medium 142 is electrically connected, directly or indirectly via conductive shielding 106, to several electrically conductive layer structures 150 stacked along the stack direction 112.

[0162] Supporting electrically insulating structure 162 may be provided on top of the top layer of the conductive shielding 106. When an electrically insulating layer is applied on the top of the conductive shielding 106, the copper of the top portion of conductive shielding 106 can be thinner compared to Figure 1. For manufacturing reasons in Figure 1, the top layer of the shielding structure may have a thickness of at least 250 pm, in order to construct a robust cantilever like structure.

[0163] Although not shown in each of Figures 1 to 16, a dielectric structure 161 according to Figure 14 may be optionally realized in each embodiment.

[0164] Specific benefits of the embodiment of Figure 14 are advantageous properties in terms of directivity, bandwidth and radiation efficiency.

[0165] Figure 15 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0166] The embodiment of Figure 15 differs from the embodiment of Figure 14 in particular in that, according to Figure 15, two patch structures 156, 156 are provided on top of each other as said antenna 108. Said two patch structures 156, 156 may be formed as patterned electrically conductive structures of two uppermost vertically spaced electrically conductive layer structures 150 of the stack 102. Upper patch structure 156 is formed by patterned electrically conductive layer structure 150 arranged on a top main surface of the uppermost electrically insulating layer structure 152 of component carrier 100 according to Figure 15. Lower patch structure 156 is formed by patterned electrically conductive layer structure 150 arranged at a bottom main surface of the uppermost electrically insulating layer structure 152 of component carrier 100 according to Figure 15. In comparison to Figure 14, the lower patch structure 156 according to Figure 15 is added. Hence, a stacked array of two patch structures 156, 156 is provided according to Figure 15. This ar- rangement may also be denoted as aperture coupled stacked patch structures 156, 156.

[0167] In addition to the specific advantages of the embodiment of Figure 14, the embodiment of Figure 15 has the additional advantages of a further improved directivity and a further increased bandwidth. The provision of two patch structures 156, 156 may allow to adjust more than one resonance frequency, in particular two different resonance frequencies, of the waveguideantenna arrangement.

[0168] Figure 16 illustrates a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the invention.

[0169] The embodiment of Figure 16 differs from the embodiment of Figure 15 in particular in that, according to Figure 16, three patch structures 156, 156, 156 are provided on top of each other. Said three patch structures 156, 156, 156 may be formed as patterned electrically conductive structures of three vertically spaced electrically conductive layer structures 150 of the stack 102. In comparison with the embodiment of Figure 15, the embodiment of Figure 16 may be obtained by stacking two further electrically insulating layer structures 152 on top of the structure of Figure 15 and by forming a patterned electrically conductive structure on top of the obtained stack 102. Uppermost patch structure 156 is formed by patterned electrically conductive layer structure 150 arranged at a top main surface of the uppermost electrically insulating layer structure 152 of component carrier 100 according to Figure 16. Lowermost patch structure 156 is formed by patterned electrically conductive layer structure 150 arranged at a top side of non-conductive low loss high frequency structure 154 and formed on a bottom main surface of an electrically insulating layer structure 152 closing the top side of the non-conductive low loss high-frequency structure 154. Central patch structure 156 is formed vertically between the uppermost and the lowermost patch structures 156, 156 and is formed on a top main surface of the electrically insulating layer structure 152 closing the top side of non-conductive low loss high frequency structure 154. Hence, a stacked array of three patch structures 156, 156, 156 is provided according to Figure 16.

[0170] In addition to the specific advantages of the embodiment of Figure 15, the embodiment of Figure 16 has the additional advantages of a further improved directivity and a further increased bandwidth, since the provision of three patch structures 156, 156, 156 may allow to adjust even three different resonance frequencies, if desired.

[0171] It should be understood that even a multi patch or stacked patch arrangement, as shown in Figure 15 and Figure 16, can be configured for and operated with only a single frequency. However, there is the option to configure and operate such an arrangement with multiple frequencies. A skilled person will understand that even more than three stacked patch antennas 108" are possible in other embodiments.

[0172] In an embodiment, it may be possible to have a plurality of (for example two or three) cavities 104, in particular waveguides, which may be coupled or connected to only one non-conductive low loss high frequency structure, in particular a cavity (see reference sign 154). This may allow to create a filter function without having a dedicated physical filter structure. For example, a first waveguide may have a first frequency bandwidth range and a second waveguide may have another second frequency bandwidth range. Through a combination of both waveguides, an effective frequency bandwidth range may be obtained which may differ from said first frequency bandwidth range and from said second frequency bandwidth range.

[0173] The stack-ups can have more layers or less layers depending on the design and requirements. The embedding of an IC can be added to all embodiments. Different combinations of prepreg and cores can be used, it is not intended to limit the designs to one specific stack-up, rather a general concept.

[0174] It should be noted that the term "comprising" does not exclude other elements or steps and the "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined.

[0175] It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.

[0176] Implementation of the invention is not limited to the preferred embodiments shown in the figures and described above. Instead, a multiplicity of variants are possible which use the solutions shown and the principle according to the invention even in the case of fundamentally different embodiments.

Claims

Claims:

1. A component carrier (100), wherein the component carrier (100) comprises: a stack (102) comprising a plurality of electrically conductive layer structures (150) and at least one electrically insulating layer structure (152); a cavity (104) formed in the stack (102) and being delimited by a peripheral wall; a conductive shielding (106) covering at least part of the peripheral wall of the cavity (104); a non-conductive low loss high frequency structure (154) above said cavity (104); and an antenna (108) at least partially above said low loss high frequency structure (154).

2. The component carrier (100) according to claim 1, wherein the low loss high frequency structure (154) comprises a further cavity above said cavity (104).

3. The component carrier (100) according to claim 2, wherein said further cavity is air-filled or is filled with a low DK and / or low DF material.

4. The component carrier (100) according to claim 2 or 3, wherein the further cavity is closed on a top side, in particular at least partially by said antenna (108).

5. The component carrier (100) according to claim 1, wherein the low loss high frequency structure (154) comprises a layer of low DK and / or low DF material, in particular extending over an entire width of the stack (102).

6. The component carrier (100) according to any of claims 1 to 5, wherein said antenna (108) is a slot antenna (108').

7. The component carrier (100) according to any of claims 1 to 5, wherein said antenna (108) is a dielectric resonator antenna (108"').

8. The component carrier (100) according to any of claims 1 to 5, wherein said antenna (108) is a patch antenna (108").

9. The component carrier (100) according to claim 8, wherein the patch antenna (108") comprises an electrically conductive patch structure (156) on at least one of the at least one electrically insulating layer structure (152).

10. The component carrier (100) according to claim 9, wherein the patch antenna (108") comprises at least one further electrically conductive patch structure (156) above said electrically conductive patch structure (156).

11. The component carrier (100) according to claim 10, comprising one or more vertical through connections (130) interconnecting said electrically conductive patch structure (156) with said at least one further electrically conductive patch structure (156) and extending through at least one of said at least one electrically insulating layer structure (152).

12. The component carrier (100) according to claim 11, wherein said vertical through connections (130) are arranged in a matrix pattern along rows and columns, for example equidistantly from each other.

13. The component carrier (100) according to claim 11 or 12, wherein said vertical through connections (130) have the same size and / or the same shape.

14. The component carrier (100) according to any of claims 8 to 13, wherein at least part of the patch antenna (108") is arranged in or on the non- conductive low loss high frequency structure (154).

15. The component carrier (100) according to any of claims 8 to 14, wherein the patch antenna (108") comprises at least a portion of at least one of the electrically conductive layer structures (150) of the stack (102).

16. The component carrier (100) according to any of claims 1 to 15, comprising an array of at least two antennas (108) being spaced with respect to each other in a horizontal plane and / or along a vertical direction.

17. The component carrier (100) according to any of claims 1 to 16, comprising a frequency filter structure (158) in and / or on said stack (102).

18. The component carrier (100) according to claim 17, wherein said frequency filter structure (158) is arranged at a feedline (160) below said cavity (104), at said cavity (104), and / or on top of said low loss high frequency structure (154).

19. The component carrier (100) according to any of claims 1 to 18, wherein the conductive shielding (106) has a coupling slot (110) on a top extremity of said cavity (104), said coupling slot (110) being vertically associated with the antenna (108) provided on top of said coupling slot (110).

20. The component carrier (100) according to any of claims 1 to 19, wherein a top portion of said conductive shielding (106), in particular a top portion of said conductive shielding (106) in which the coupling slot (110) is formed, is a freely hanging structure.

21. The component carrier (100) according to any of claim 19 or 20, wherein a top portion of said conductive shielding (106) in which said coupling slot (110) is formed has a supporting electrically insulating structure (162) arranged on a top surface and / or on a bottom surface of said top portion of said conductive shielding (106) and arranged around said coupling slot (110).

22. The component carrier (100) according to any of claims 1 to 21, comprising a lens component (182) being surface-mounted on the stack (102).

23. The component carrier (100) according to any of claims 1 to 22, wherein the antenna (108) is formed as part of said stack (102), for example at least partially at an exterior surface of the stack (102).

24. The component carrier (100) according to any of claims 19 to 23, wherein the conductive shielding (106) has a further coupling slot (110) on the top extremity of said cavity (104) side by side with said coupling slot (HO).

25. The component carrier (100) according to any of claims 1 to 24, wherein the conductive shielding (106) comprises a feeding slot (132) on a bottom extremity of said cavity (104).

26. The component carrier (100) according to claim 25, wherein said coupling slot (110) and said feeding slot (132) have different sizes and / or shapes.

27. The component carrier (100) according to claims 25 and 26, wherein said coupling slot (110) and said feeding slot (132) are arranged parallel to each other.

28. The component carrier (100) according to any of claims 19 to 27, wherein a maximum width (W) of at least one of the coupling slot (110) and the feeding slot (132) is not more than 12 mm.

29. The component carrier (100) according to any of claims 1 to 28, wherein one of the at least one electrically insulating layer structure (152) delimiting a top side of the low loss high frequency structure (154) is a core, for example with a thickness (D) in a range from 50 pm to 600 pm, in particular in a range from 100 pm to 300 pm.

30. The component carrier (100) according to any of claims 1 to 29, comprising a venting hole (165) fluidically coupling or contributing to a pressurecoupling of said low loss high frequency structure (154) with an environment external to the stack (102) or with yet another cavity.

31. The component carrier (100) according to claim 30, wherein said venting hole (165) is closed by a membrane (166).

32. The component carrier (100) according to any of claims 1 to 31, wherein said low loss high frequency structure (154) extends in a vertical direction over at least two electrically insulating layer structures (152) of the stack (102).

33. The component carrier (100) according to any of claims 1 to 32, wherein a vertical extension (h) of said low loss high frequency structure (154) is smaller than a vertical extension (H) of said cavity (104).

34. The component carrier (100) according to any of claims 1 to 33, wherein a horizontal extension (L) of said low loss high frequency structure (154) is larger than a horizontal extension (I) of said cavity (104).

35. The component carrier (100) according to any of claims 1 to 34, wherein at least part of sidewalls of said low loss high frequency structure (154) is lined with a metallization layer (133) or is provided with a metal fence.

36. The component carrier (100) according to any of claims 1 to 35, wherein the cavity (104) is filled with a medium, in particular air.

37. The component carrier (100) according to any of claims 1 to 36, wherein the cavity (104) is configured for a frequency of at least 60 GHz.

38. A method of manufacturing a component carrier (100), wherein the method comprises: forming a cavity (104) in a stack (102) comprising at least two electrically conductive layer structures (150) and at least one electrically insulating layer structure (152), said cavity (104) being delimited by a peripheral wall;forming a conductive shielding (106) to cover at least part of the peripheral wall of the cavity (104); forming a non-conductive low loss high frequency structure (154) above said cavity (104); and forming an antenna (108) at least partially on top of said low loss high frequency structure (154).

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