Patent Publication Number: US-2023135105-A1

Title: Component Embedded in Component Carrier and Having an Exposed Side Wall

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 16/051,618 and claims in part the benefit of the filing date of European Patent Application No. 17185037.3, filed on Aug. 4, 2017, the disclosures of which are hereby incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the invention relate to a method of manufacturing a component carrier, and to a component carrier. 
     BACKGROUND ART 
     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. Moreover, an extended functionality of component carriers with embedded component is demanded by users. 
     SUMMARY 
     There may be a need to integrate a component in a component carrier in a way to allow for an efficient and reliable operation while enabling a high degree of functionality. 
     To address this need and perhaps other needs, a method of manufacturing a component carrier, and a component carrier according to the independent claims are provided. 
     According to an exemplary embodiment there is provided a component carrier which comprises (i) a stack comprising a plurality of electrically conductive layer structures and/or electrically insulating layer structures and (ii) an optical component embedded in the stack. At least a portion of a side wall of the optical component is exposed. 
     According to an exemplary embodiment there is provided a method of manufacturing a component carrier, wherein the method comprises (i) forming a stack of a plurality of electrically conductive layer structures and/or electrically insulating layer structures; (ii) embedding an optical component in the stack; and (iii) subsequently removing material of the stack to thereby expose at least a portion of a side wall of the optical component with regard to an environment of the component carrier. 
     According to another exemplary embodiment, a component carrier is provided which comprises a stack comprising a plurality of electrically conductive layer structures and/or electrically insulating layer structures, and a component embedded in the stack, wherein at least a portion of a side wall of the component is exposed (for instance with regard to an environment of the component carrier). 
     According to another exemplary embodiment, a method of manufacturing a component carrier is provided, wherein the method comprises forming a stack of a plurality of electrically conductive layer structures and/or electrically insulating layer structures, embedding a component in the stack, and subsequently removing material of the stack to thereby expose at least a portion of a side wall of the component. 
     OVERVIEW OF EMBODIMENTS 
     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. 
     In the context of the present application, the term “embedded component” may particularly denote any body or member not in the shape of and having a lower dimension than the layer structures of the layer stack and being nevertheless accommodated in an interior of component carrier material (i.e., stack material, for instance resin with reinforcing particles as dielectric material and copper as electrically conductive material). The accommodation of the component in the component carrier material may be accomplished by lamination, i.e., the application of pressure and/or heat for integrally connecting the constituents of the component carrier. 
     In the context of the present application, the term “exposed side wall” may particularly denote a lateral side wall portion of the component embedded in component carrier material, which lateral side wall portion is not covered by component carrier material, in particular is not covered at all with solid material. Thereby, an exposed side wall of the component may form part of an exposed surface of the component carrier as a whole. When the component carrier is shaped as a plate with two opposing main surfaces and a circumferential edge, the side wall may form part of or may be substantially parallel to the circumferential edge and may be perpendicular to the main surfaces of the component carrier. 
     According to an exemplary embodiment, the component carrier further comprises an access recess formed in the stack, wherein the access recess extends from a lateral side wall of the stack to the side wall of the optical component and the access recess exposes the side wall of the optical component. 
     According to an exemplary embodiment, the access recess is configured as a blind hole. 
     According to an exemplary embodiment, the component carrier further comprises a further component being inserted in the access recess. 
     According to an exemplary embodiment, the further component is an optically transparent component. 
     According to an exemplary embodiment, the further component is configured as at least one of (i) a light guide and (ii) an optical fiber. 
     According to an exemplary embodiment, the further component is configured as at least one of (i) a light detecting element and (ii) a light emitting element. 
     According to an exemplary embodiment, the further component comprises at least one reflecting surface which is configured to diverge a light beam. 
     According to an exemplary embodiment, the light beam is emitted from the optical component. 
     According to an exemplary embodiment, the further component comprises at least one optical lens which is configured to change a focus of a light beam. 
     According to an exemplary embodiment, the light beam is emitted from the optical component. 
     According to an exemplary embodiment, the access recess is a slit-shaped recess exposing a first side wall of the optical component and a second side wall of a further component. Further, (i) the first side wall and the second side wall oppose each other, (ii) the optical component and the further component are arranged opposite to each other, and (iii) the optical component and the further component are communicatively coupled for a wireless data communication via the slit-shaped access. 
     According to an exemplary embodiment, the slit-shaped access is an air gap. 
     According to an exemplary embodiment, the optical component and the further component are embedded in the stack. 
     According to an exemplary embodiment, the component carrier further comprises a transparent material being arranged between the side wall of the optical component and a lateral side wall of the stack. 
     According to an exemplary embodiment, the transparent material forms part of an optical path for propagating electromagnetic radiation. 
     According to an exemplary embodiment, the transparent material comprises at least one of (i) a fiber free material, (ii) glass, and (iii) epoxy. 
     According to an exemplary embodiment the transparent material comprises at least one of (i) at least one reflecting surface which is configured to diverge a light beam, and (ii) at least one optical lens which is configured to change a focus of a light beam. 
     According to an exemplary embodiment of the method, removing material of the stack comprises forming an access recess in the stack, wherein the access recess extends from a lateral side wall of the stack to the side wall of the optical component and the access recess exposes the side wall of the optical component with regard to the environment of the component carrier. 
     According to an exemplary embodiment of the method, removing material of the stack further comprises performing a cutting procedure of the stack. 
     According to an exemplary embodiment of the method, the optical component is at least in part circumferentially covered by a transparent material. 
     According to an exemplary embodiment of the method, removing material of the stack further comprises, after performing the cutting procedure, performing a lateral polishing procedure which smoothes a side wall surface of the transparent material. 
     In the following, further exemplary embodiments of the component carrier and of the method of manufacturing a component carrier are described. 
     According to an exemplary embodiment, a component carrier with an embedded component is provided which is exposed laterally, i.e., at its side wall. This can be accomplished in a highly accurate way by removing material of a stack of connected layer structures in which the component is embedded after the embedding procedure is completed to thereby expose the lateral side surface. But taking this measure, it becomes possible to functionally use a side wall of a component for establishing a connection or coupling with an environment, for instance for sensor or optoelectronic applications. The upper and lower main surfaces of the stack and hence of the component carrier may thereby remain available for mounting further components, etc. The described architecture thereby renders it possible to keep component carriers compact without compromising on the functionality thereof. In contrast to this, a lateral side surface of the component carrier may be made available as a functional part of the component. 
     In the following, further exemplary embodiments of the method and the component carrier will be explained. 
     In an embodiment, the exposed side wall and a side wall of the stack are aligned to form a substantially continuous (for instance substantially vertical) side wall of the component carrier. In other words, it is possible that the exposed side wall of the component and the side wall of the stack are aligned with one another or are in flush with one another. This prevents undercuts at the side wall of the component carrier in which contaminants such as dust may accumulate. 
     In another embodiment, an access recess exposing the side wall extends laterally from a lateral side wall of the stack up to the lateral side wall of the component. In such an embodiment, it is possible to space the exposed side wall of the component with regard to the side wall of the component carrier. Such an architecture may for instance be advantageous when a mechanical, an optical, an electrical or an electro-optical coupling of the exposed component with a periphery shall be established via an electric or optical cable. For instance, an electric lead or an optical fiber may be inserted into the access recess so as to establish an electric, optical and/or electro-optical coupling. 
     In another embodiment, an access recess exposing the side wall extends from one of two opposing main surfaces of the stack up to the component. In other words, the access recess may be formed as a (blind or through) hole which may extend from one of the two opposing main surfaces at least up to the embedded component or even up to the other main surface. In such an embodiment, the embedded component remains securely mechanically protected in the interior of the stack while nevertheless being functionally coupled to an exterior environment of the component carrier. For instance, such an embodiment may be used for a gas, chemical or moisture sensor having its sensitive surface at the exposed side wall of the component. 
     In an embodiment, the access recess is a slit extending into a central portion of the stack. Preferably, the slit has a length being larger than a width. For instance, the length may be at least twice the distance of the width. Such a slit may have a length being significantly longer than (in particular at least five times of) than a width. The longer extension direction of the slit may correspond to a horizontal extension direction of the side wall of the component, whereas the short extension direction may extend perpendicular to the side wall of the component. Such a slit may be simply formed by drilling, milling, or laser cutting perpendicular to a main surface of the component carrier. 
     In an embodiment, the access recess is configured as one of the group consisting of a through-hole extending through the entire stack, and a blind hole. 
     In an embodiment, only one main surface of the, in particular substantially cuboid, component is exposed. In other words, five main surfaces of the substantially cuboid component may remain covered by component carrier material of the component carrier and may thus be properly mechanically protected. The, in this case only, one side wall being exposed may then allow precisely defining the interface properties between the component and the environment. 
     In an embodiment, the component is arranged laterally asymmetrically in an accommodation cavity of the stack, in particular with different distances with regard to opposing accommodation cavity delimiting side walls of the stack. This has the advantage that the side of the cavity with the smaller distance to the component serves for securely defining the position of the component in the component carrier (for instance by constituting a lateral abutment surface for the component), wherein the other side wall of the cavity with the larger distance to the component allows exposing the side wall of the component even by processing with relatively low spatial accuracy. In other words, the larger distance value corresponds to a tolerance allowed when exposing the side wall of the component by cutting through the larger distance. 
     In an embodiment, the component comprises a sensor configured for sensing sensor information via the exposed surface. In other words, the exposed surface may comprise at least a sensitive portion for detecting a medium to be sensed. Such a medium may be electricity, electromagnetic radiation (in particular optical light), or a substance (such as a gas, a liquid, or any other chemical). Thus, exposing the lateral side wall or surface of the component allows manufacturing a component carrier with integrated sensor functionality in a compact way. 
     In an embodiment, the component comprises an electromagnetic radiation source configured for emitting electromagnetic radiation via the exposed surface. In such an embodiment, the component carrier may be capable of generating electromagnetic radiation transmitted via the exposed surface towards an environment or a communication partner device (for instance a receiver). For example, the component may be a laser diode or any other light source. 
     In an embodiment, the component carrier comprises a further component embedded in the stack, wherein the component and the further component are communicatively coupled, in particular at least partially via the access recess. For instance, the further component may be coupled to the previously mentioned component via the access recess. For example, one of the component and the further component may be a sender (for instance a light sender) and the other one of the component and the further component may be a receiver (for instance a light receiver). 
     In an embodiment, the component and the further component are configured as a pair of an electromagnetic radiation emitter (for instance capable of generating electromagnetic radiation in the visible, infrared and/or UV range) and an electromagnetic radiation detector (for instance capable of sensing electromagnetic radiation in the visible, infrared and/or UV range), a pair of a light guide (such as a light fiber) and a light emitter (such as a laser diode), or a pair of a light guide (such as a light fiber) and a light detector (such as a photodiode). 
     In an embodiment, at least one of the electrically insulating layer structures being in direct contact with or being neighbored to the embedded component (in particular being arranged directly above and/or directly below the component) is made of low-flow prepreg or no-flow prepreg. However, FR4 material may also be used. Advantageously, no-flow prepreg or low-flow prepreg will not or substantially not re-melt/not become flowable during lamination, so that a hole next to the component will not be closed during laminating by liquefied resin or the like and the side wall to be exposed can be kept free of resin material. When laminating a corresponding stack by applying mechanical pressure and/or heat, the material of the low-flow prepreg or no-flow prepreg is advantageously prevented from flowing into a hollow space between component and layer stack. By subsequently exposing the side wall of the component by removing (for instance cutting) a portion of the stack adjacent to the hollow space, it is possible to complete formation of the component carrier with embedded component having an exposed side wall. This procedure simplifies exposing the side wall of the component, for instance by milling. 
     In an embodiment, embedding the component in the stack comprises arranging the component in direct contact with a plurality of electrically conductive layer structures and/or electrically isolation layer structures such that at least five surfaces of the component are covered by the stack. Thereby, an orientation of the component with the stack can be made more precise and/or a sensitivity of the component with respect to external impacts can be decreased. 
     In an embodiment, embedding the component in the stack comprises forming an accommodation cavity (i.e., a hollow space for mounting the component) in at least one of the layer structures of the stack and placing the component in the accommodation cavity. The latter mentioned placement may be made asymmetrically in a lateral direction so that two opposing gaps between component and respective side walls of the stack have different sizes. The accommodation cavity may be formed, for example, by using a pre-cut core, by mechanically drilling or laser drilling, or by applying the concept of release layers. Such a release layer may be a layer (for instance made of a waxy material) on which other component carrier material of the stack does not properly adhere. Cutting a circumferentially closed hole above such a release layer may therefore allow removal of a piece of the stack above the release layer to thereby complete formation of the cavity. 
     In an embodiment, the component is placed in the accommodation cavity so that a size of a gap between a side wall of the component and an accommodation cavity delimiting side wall of the stack is different from a further size of a further gap between an opposing further side wall of the component and an opposing further accommodation cavity delimiting side wall of the stack. At a side wall of the component which shall not be exposed after embedding, the size of the gap shall be as small as possible so as to precisely define the position of the component in the component carrier. In contrast to this, at an opposing other side wall of the component which shall be exposed later the dimension of the gap may be advantageously larger so that the accuracy of removing material for exposing the component on the corresponding side thereof need not be very high. This relaxes the requirements of spatial accuracy during stack material removal in terms of exposing the side wall. 
     In an embodiment, the method further comprises filling at least part of a gap between the component and an accommodation cavity delimiting side wall of the stack with a removable sacrificial material, and at least partially removing the sacrificial material after completion of the embedding, in particular to thereby expose the side wall. In this context, the term “sacrificial material” may particularly denote an auxiliary material which is provided only for temporary use and which shall later be intentionally removed so that it does not form part of the final product, i.e., component carrier. In the present embodiment, the sacrificial material is provided for preventing the component from migrating within the cavity, because a free gap of the cavity may be filled with the sacrificial material. The sacrificial material may temporarily cover the side wall to be exposed later, but may be easily removable from this side wall. The sacrificial material may thus have the property of being easily removable selectively with regard to the component material so that the sacrificial material can be later removed for exposing the side wall of the component without harming the component and without the need to apply a complex removal procedure. 
     In an embodiment, the method further comprises inserting the component in a first part of the accommodation cavity, and subsequently filling the sacrificial material into at least part of a remaining second part (as the gap) of the accommodation cavity laterally juxtaposed to the first part. Thus, the component may firstly be placed in the accommodation cavity, and a remaining gap may be filled partially or entirely with the sacrificial material, for instance using a wiper. This embodiment has the advantage that a single cavity formation process is sufficient to provide an accommodation volume for both the sacrificial material and the component. 
     In an alternative embodiment, the method further comprises forming a first cavity portion (which may later constitute the gap) in the stack and filling the first cavity portion at least partially with the sacrificial material. Subsequently, a second cavity portion may be formed separately in the stack and overlapping with the first cavity portion. In other words, the second cavity portion may be composed of part of the first cavity portion and of an adjacent portion of the stack which is removed. It is then possible to insert the component into the second cavity portion so that the first cavity portion at least partially filled with the sacrificial material and the second cavity portion accommodating the component together constitute the accommodation cavity. Thus, it is possible that a first cavity (or first cavity portion of the accommodation cavity) is formed in the stack and is filled with the sacrificial material, for instance using a wiper. Optionally, the sacrificial material may then be cured. It is then possible to form, thereafter and separately, a second cavity (or second cavity portion of the accommodation cavity) which partially overlaps with the first cavity. In this context, it is also possible to remove a portion of the sacrificial material in the overlapping volume. The component may then be placed in the second cavity. An advantage of such an embodiment is that the process of applying the sacrificial material is simplified and rendered more accurate, since it can be applied in a first cavity portion of relatively large size, and not limited to a small gap between component and side wall of the stack next to the cavity. Another advantage of such an approach is that a potential curing process for curing the sacrificial material may be carried out prior to the insertion of the component, so that the component is not harmed by curing conditions (for instance an elevated temperature). 
     In an embodiment, the sacrificial material comprises one of the group consisting of a release structure with non-adhesive properties with regard to the material of the stack and the component, an evaporable liquid, a liquid which can be flushed out, and a substance which can be dissolved (for instance by water or an aqueous solution). Such a release structure may for instance be made of a waxy material or may be based on polytetrafluoroethylene. A suitable evaporable liquid is water or alcohol. A liquid which can be flushed out can be substantially any liquid which may be later removed from the gap to thereby expose the side wall by applying pressurized gas, etc. 
     In an embodiment, the method further comprises providing the component with a removable sacrificial material thereon, in particular a release structure, prior to the embedding, subsequently embedding the component with the removable sacrificial material thereon into the stack, and at least partially removing the sacrificial material after completion of the embedding, in particular to thereby expose the side wall. Thus, it is also possible to apply a release layer or another sacrificial material directly on the component before initiating the embedding procedure. This renders it dispensable to apply a sacrificial material in a tiny gap. 
     In an embodiment, removing the material of the stack comprises at least one of a group consisting of milling and laser cutting. For instance, an edge section of the component carrier may be removed by milling or laser cutting to thereby expose the side wall of the component. 
     In an embodiment, a size of a lateral gap between the component and an accommodation cavity delimiting side wall of the stack is at least 50 μm, in particular at least 300 μm, more particularly at least 500 μm. For instance, the size of the lateral gap may be in a range between 5 μm and 500 μm. This allows carrying out the material removing procedure with low accuracy requirements. 
     In an embodiment, embedding the component comprises laminating the component with the stack so that at least partially uncured material of the layer structures is cured. Curing may for instance be established by pressurising and heating curable resin which thereby starts cross linking. During the curing, the resin temporarily melts, flows into tiny gaps, re-solidifies, and thereby interconnects the various constituents of the component carrier. Thereby, a mutual integral connection between the stack and the component can be ensured, and consequently a high mechanical integrity of the component carrier as a whole. 
     In an embodiment, forming the stack comprises attaching a temporary carrier to the layer structures when the latter are still in a condition to comprise at least partially uncured material. In an embodiment, the temporary carrier comprises a sticky surface facing the component carrier material and the recess or cavity. Providing the temporary carrier with a sticky surface simplifies connection of the temporary carrier on the component carrier material, in particular a core having a through-hole, closed by the temporary carrier. In an embodiment, the temporary carrier comprises a rigid plate. It is advantageous that the temporary carrier has a rigid plate providing the semifinished product still including the temporary carrier with additional stability during a lamination procedure by which further layers are built up. However, as an alternative to a rigid plate (preferably having a sticky upper surface), it is also possible that the temporary carrier is a sticky foil or tape being flexible. 
     In an embodiment, it is possible to remove the temporary carrier from the stack after curing the at least partially uncured material of the layer structures. Since after curing, the previously uncured material has been cured and hardened, the provision of mechanical support by the temporary carrier may be dispensable after completion of the lamination and curing procedure. For instance, the temporary carrier may be simply peeled off from the semifinished product after lamination. 
     In an embodiment, the component comprises an electromagnetic radiation emitting member (such as a light-emitting diode) configured for emitting electromagnetic radiation (such as visible light), more specifically via a side surface thereof, and being at least partially covered by an optically transparent (in particular transparent in the visible range) material at least partially forming the exposed side wall and being transparent for the electromagnetic radiation emitted by the electromagnetic radiation emitter member. The transparent material may for instance encapsulate the electromagnetic radiation emitter member and may therefore simultaneously protect the latter while at the same time enabling propagation of electromagnetic radiation through the transparent material out of the component carrier via a side wall thereof. Preferably, the transparent material may be a resin (being properly compatible with other component carrier material of the stack) being free of fibers (which might deteriorate the undisturbed propagation of the electromagnetic radiation) or the like. 
     In an embodiment, at least part of the transparent material at least partially forming the exposed side wall is polished. Polishing the exposed sidewall of the transparent material to decrease roughness thereof has the particular advantage that undesired diffraction processes at the transition area between transparent material and surrounding of the component carrier can be strongly suppressed. Such a scattering may unintentionally and undesirably increase a cross-sectional area of the propagating beam of electromagnetic radiation, which may involve losses. However, diffraction may be suppressed by polishing the planar exposed sidewall, and a substantially parallel light beam may propagate out of the component carrier with reduced losses. 
     The mentioned component, and optionally at least one further component to be surface mounted on or embedded in the component carrier, 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. For example, the component can be an active electronic component, a passive electronic component, an electronic chip, a storage device (for instance a DRAM or another data memory), a filter, an integrated circuit, a signal processing component, a power management component, an optoelectronic interface element, 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 inductance, a battery, a switch, a camera, an antenna structure, a logic chip, a light guide, 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 or a ferrimagnetic element, for instance a ferrite coupling structure) or may be a paramagnetic element. However, the component may also be 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 may be used as component. 
     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, if desired supported by 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. The term “layer structure” may particularly denote a continuous layer, a patterned layer or a plurality of non-consecutive islands within a common plane. 
     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. 
     In an embodiment, the component carrier is configured as one of the group consisting of a printed circuit board, and a substrate (in particular an IC substrate). 
     In the context of the present application, the term “printed circuit board” (PCB) may particularly denote a component carrier (which may be plate-shaped (i.e., planar), three-dimensionally curved (for instance when manufactured using 3D printing) or which may have any other shape) which is formed by laminating several electrically conductive layer structures with several electrically insulating layer structures, for instance by applying pressure, if desired accompanied 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 FR4 material. The various electrically conductive layer structures may be connected to one another in a desired way by forming through-holes through the laminate, for instance by laser drilling or mechanical drilling, and by filling them with electrically conductive material (in particular copper), thereby forming vias as through-hole connections. 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 plate-shaped 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). 
     In the context of the present application, the term “substrate” may particularly denote a small component carrier having substantially the same size as a component (in particular an electronic component) to be mounted thereon. 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 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 spheres (such as glass spheres). 
     In an embodiment, the at least one electrically insulating layer structure comprises at least one of the group consisting of resin (such as reinforced or non-reinforced resins, for instance epoxy resin or Bismaleimide-Triazine resin, more specifically FR-4 or FR-5), cyanate ester, polyphenylene derivate, glass (in particular glass fibers, multi-layer glass, glass-like materials), prepreg material, polyimide, polyamide, liquid crystal polymer (LCP), epoxy-based Build-Up Film, polytetrafluoroethylene, a ceramic, and a metal oxide. Reinforcing materials such as webs, fibers or spheres, for example made of glass (multilayer glass) may be used as well. Although prepreg or FR4 are usually preferred, other materials may be used as well. For high frequency applications, high-frequency materials such as polytetrafluoroethylene (PTFE), liquid crystal polymer and/or cyanate ester resins may be implemented in the component carrier as electrically insulating layer structure. 
     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, and tungsten. Although copper is usually preferred, other materials or coated versions thereof are possible as well, in particular materials coated with supra-conductive material such as graphene. 
     In an embodiment, the component carrier is a laminate-type body. 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, if desired accompanied by heat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1   ,  FIG.  2   , and  FIG.  3    illustrate cross-sectional views of pre-forms of component carriers manufactured according to exemplary embodiments. 
         FIG.  4   ,  FIG.  5   ,  FIG.  6   ,  FIG.  7   , and  FIG.  8    illustrate cross-sectional views of structures obtained during manufacturing a component carrier, shown in  FIG.  8   , according to an exemplary embodiment. 
         FIG.  9   ,  FIG.  10   ,  FIG.  11   , and  FIG.  12    illustrate cross-sectional views of structures obtained during manufacturing a component carrier according to another exemplary embodiment. 
         FIG.  13    and  FIG.  14    illustrate a cross-sectional view and a plan view of a component carrier according to another exemplary embodiment. 
         FIG.  15    illustrates a cross-sectional view of a component carrier according to another exemplary embodiment. 
         FIG.  16    illustrates a cross-sectional view of a component carrier according to still another exemplary embodiment. 
         FIG.  17   ,  FIG.  18   ,  FIG.  19   , and  FIG.  20    illustrate cross-sectional views of structures obtained during manufacturing a component carrier according to another exemplary embodiment. 
         FIG.  21    illustrates a cross-sectional view of three component carriers arranged side by side according to another exemplary embodiment. 
         FIG.  22    illustrates an example showing a light-emitting diode emitting light through transparent material. 
         FIG.  23   ,  FIG.  24   , and  FIG.  25    show different structures obtained during manufacturing a component carrier according to an exemplary embodiment which is shown, in operation, in  FIG.  26   . 
         FIG.  27    illustrates spectacles according to an exemplary embodiment comprising the component carrier shown in  FIG.  26   . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS 
     Embodiments of the component carrier can be better understood with reference to the following drawings. The elements and features in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the structures and principles of operation of the assemblies. 
     The illustrations in the drawings are schematically presented. In different drawings, similar or identical elements are provided with the same reference signs. 
     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. 
     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. 
     According to an exemplary embodiment, a component carrier with an embedded component having a lateral opening is provided. Exposing the component on one side has the advantage that new opportunities for embedding are made possible. For instance, plug in connections as well as optical connections can be accomplished in this way. Thus, it becomes possible to expose embedded components from a component carrier with high spatial accuracy at the side wall of the component. 
     A gist of an exemplary embodiment is that an embedded component can be exposed at a flange face thereof with high positional accuracy. Advantageously, the manufacturing method may be configured so that the components to be exposed at a side surface thereof shall preferably not be covered with resin there. In one embodiment, it may be ensured that the side wall surface of the embedded component remains free of any material. This may be for instance accomplished by using channels or hollow spaces around the embedded component using no-flow prepreg or low-flow prepreg for lamination. In another embodiment, the side wall may be temporarily covered with sacrificial material of such a kind that it can be selectively and easily removed later by carrying out simple technical methods. For instance, a release material paste may be arranged next to the component which fixes the component in place at a desired position. However, the material of the release material paste may be easily removed (for instance by stripping) after having removed material of the stack of electrically conductive layer structures and/or electrically insulating layer structures for exposing the side wall. All these concepts have in common that they allow an exposure of a side wall of a component embedded in component carrier material with high precision. Such a manufacturing architecture increases the flexibility of designing component carrier type modules with improved functionality. 
       FIG.  1    illustrates a cross-sectional view of a pre-form of a component carrier  100 , which is here embodied as a printed circuit board (PCB), manufactured according to an exemplary embodiment. 
     The plate-shaped laminate-type component carrier  100  which can be separated from the structure of  FIG.  1    comprises a laminated stack  102  of component carrier material comprising a plurality of electrically conductive layer structures  104  (here embodied as patterned metal foils and metal vias, both preferably made of copper) and a plurality of electrically insulating layer structures  106  (here embodied as resin layers, in particular epoxy based resin layers, with reinforcing fibers, in particular glass fibers, for example prepreg). 
     Moreover, the component carrier  100  comprises an electronic component  108 , which may for instance be a semiconductor chip. The electronic component  108  may be electrically coupled with an electronic environment via the electrically conductive layer structures  104 . The component  108  is embedded in the component carrier material of the stack  102 . According to  FIG.  1   , a side wall  110  of the component  108  is still surrounded by material of the stack  102 . However, a milling tool  121  is shown in  FIG.  1    which is currently in the process of removing material of the stack  102  on the right-hand side of the milling tool  121  from remaining material of the stack  102  on the left-hand side of the milling tool  121 . As a result of this milling procedure, a component carrier  100  is obtained having an embedded component  108  with an exposed side wall  110 . More specifically, the side wall  110  of the component  108  is exposed with regard to an environment of the component carrier  100  after separation by milling, so that the side wall  110  then forms part of an exterior lateral side wall of the component carrier  100 . 
     The component carrier  100  manufactured according to  FIG.  1    can be obtained by firstly cutting cavities (see reference numeral  122  in  FIG.  4   ) in a core  123  (i.e., fully cured resin material of the electrically insulating layer structures  106 ) as accommodation volumes for components  108 . As can be taken from a detail  131  in  FIG.  1   , the dimension of the cavities may be selected so that a gap  126  (between side wall  110  of component  108  and accommodation cavity delimiting side wall  112  of stack  102 ) having a dimension, D, of for instance 500 μm thickness remains after placing the components  108  in the cavities on the right-hand side according to  FIG.  1   . In contrast to this, a further gap  129  on the opposing other side of the component  108 , i.e., on the left-hand side according to  FIG.  1   , may have a significantly smaller dimension of, for instance, 75 μm. This increases the accuracy of the positional placement of the component  108  in the component carrier  100 . Thereafter, a temporary carrier (for instance a sticky tape) may be placed on a bottom surface of the core  123  for closing the cavities at a bottom side. Thereafter, the components  108  are fixed in the cavities and on the temporary carrier. A dielectric layer on top of the component  108  as well as on top of the core  123  may then be laminated from an upper side. The said dielectric layer may be made preferably of no-flow prepreg or low-flow prepreg in order to prevent filling of the mentioned gaps  126 ,  129  during lamination by prepreg material melting during lamination and flowing into the respective gap  126 ,  129 . Such a flow of resin is disabled or at least strongly suppressed when using no-flow prepreg or low-flow prepreg above and below gaps  126 ,  129 . This prevention of flow of resin material in particular into the gap  126  strongly simplifies subsequent exposure of the side wall  110  of the component  108  by milling. Since the gap  126  remains free of resin, the side wall  110  of the component  108  is free of resin after the exposing procedure. 
       FIG.  2    illustrates a cross-sectional view of a pre-form of a component carrier  100  manufactured according to another exemplary embodiment. 
     The embodiment of  FIG.  2    differs from the embodiment of  FIG.  1    in that the removal of material of the stack  102  for exposing side wall  110  of embedded component  108  of component carrier  100  is carried out by laser cutting rather than by milling. Furthermore, the embodiment of  FIG.  2    differs from the embodiment of  FIG.  1    in that the mentioned gap  126  is filled with a release material paste, as sacrificial material  128 , according to  FIG.  2   . The release material paste may be made of a waxy material or may be formed based on polytetrafluoroethylene (PTFE). After separating the component carrier  100  from the electrically conductive layer structures  104  as well as the electrically insulating layer structures  106  on the right-hand side of schematically illustrated laser cutting tool  125 , the sacrificial material  128  embodied as release material paste may be easily removed due to its poor adhesion to component carrier material and to the component  108 . Thereafter, the side wall  110  of the component  108  is exposed from sacrificial material  128  and then forms part of a lateral side surface of the component carrier  100 . 
     More specifically, the component carrier  100  manufactured according to  FIG.  2    can be obtained by firstly cutting cavities in core  123  as accommodation volumes for components  108 . The dimension of the cavities may be selected so that gap  126  having a dimension of for instance 100 μm thickness remains after placing the components  108  in the cavities on the right-hand side according to  FIG.  2   . Thereafter, a temporary carrier (for instance a sticky tape) may be placed on a bottom surface of the core  123  for closing the cavities from a bottom side. Thereafter, the components  108  are fixed in the cavities and on the temporary carrier. The sacrificial material  128  in form of the release material paste may then be inserted into the gap  126  of the cavity, for instance by a wiper, and may be cured. The release material paste prevents resin material from adhering to the side wall  110  of the component  108  to be exposed. The dielectric layer on top of the component  108  as well as on top of the core  123  may be laminated from an upper side. The said dielectric layer may be made of ordinary prepreg, no-flow prepreg or low-flow prepreg. Filling of the mentioned gap  126  during lamination is here prevented by the presence of the sacrificial material  128 , regardless of the prepreg type used. The temporary carrier may then be removed and a further lamination procedure may be carried out at a bottom side (for instance using a further prepreg foil and a further copper foil). 
     The gap  126  filled with the sacrificial material  128  can then be opened by laser cutting using laser cutting tool  125 , and the release material paste material may be stripped. By stripping the release material paste, side wall  110  is exposed. Since the sacrificial material  128  may be easily removed out of the gap  126  after the laser cutting, the side wall  110  of the component  108  is exposed and is in particular free of resin after the exposing procedure. 
       FIG.  3    illustrates a cross-sectional view of a pre-form of a component carrier  100  manufactured according to still another exemplary embodiment. 
     The embodiment according to  FIG.  3    differs from the embodiment according to  FIG.  2    in particular in that two different cavities are formed, i.e., firstly a cavity for sacrificial material  128  (such as release layer material) only, and after supply and curing of the sacrificial material  128 , a second cavity overlapping with the first cavity and being configured for mounting a component  108  therein can be formed. 
     More specifically, the component carrier  100  manufactured according to  FIG.  3    can be obtained by firstly cutting first cavities in core  123  as accommodation volumes for sacrificial material  128 . Thereafter, a first temporary carrier (for instance a sticky tape) may be placed on a bottom surface of the core  123  for closing the first cavities from a bottom side. Thereafter, the sacrificial material  128  may be supplied to the first cavities and on the temporary carrier, for instance by a wiper. The sacrificial material  128  may then be cured. The temporary carrier may then be removed. Second cavities may then be cut in core  123  overlapping with the first cavities as accommodation volumes for components  108 . A further temporary carrier (for instance a further sticky tape) may be placed on a bottom surface of the core  123  with the sacrificial material  128  for closing the second cavities from a bottom side. Thereafter, the components  108  may be placed in the second cavities juxtaposed to the cured sacrificial material  128 . A lamination procedure may be carried out (for instance using a prepreg foil and a copper foil) at a surface of the structure facing away from the second temporary carrier. The second temporary carrier may then be removed. A further lamination procedure may be carried out (for instance using a further prepreg foil and a further copper foil). 
     The gap  126  filled with the sacrificial material  128  can then be opened by laser cutting using laser cutting tool  125 , and the release material paste material may be stripped. By stripping the release material paste, a hollow space is formed on the left-hand side of the component  108  according to  FIG.  3   , thereby exposing side wall  110 . Since the sacrificial material  128  may be easily removed out of the gap  126  after the laser cutting, the side wall  110  of the component  108  is free of resin after the exposing procedure. 
     Although not shown in the figures, the release material paste constituting the sacrificial material  128  according to  FIG.  2    and  FIG.  3    may be substituted by other sacrificial material  128  being selectively removable with regard to material of the components  108 . For instance, a water-soluble material may be used as sacrificial material  128 , for instance a salt or an appropriate polymer (for instance polyvinyl alcohol). The sacrificial material  128  may be removed to thereby expose the side wall  110  of the components  108  by supply of water. 
       FIG.  4    to  FIG.  8    illustrate cross-sectional views of structures obtained during manufacturing a component carrier  100 , shown in  FIG.  8   , according to an exemplary embodiment. This embodiment is similar to the embodiment of the component carrier  100  of  FIG.  1   . 
     Referring to  FIG.  4   , a stack  102  of a core  123  of fully cured resin with reinforcing particles (for instance FR4) as electrically insulating layer structure  106  covered on both opposing main surfaces thereof with a respective one of two electrically conductive layer structures  104  (here embodied as copper foils) is shown. An accommodation cavity  122  is formed as a through hole through the stack  102 . The stack  102  is arranged on a temporary carrier  130 , such as a sticky tape, so that an open bottom of the accommodation cavity  122  is closed by a portion of the temporary carrier  130 . Thereafter, a component  108  (such as a laser diode for emitting electromagnetic radiation, a photodiode for detecting electromagnetic radiation, or a sensor such as a chemo sensor) may be inserted into the accommodation cavity  122  of the stack  102  and may be attached to a surface of the temporary carrier  130 . As can be taken from  FIG.  4   , the component  108  is placed asymmetrically in the accommodation cavity  122  in a lateral direction so that a gap  126  between a side wall  110  of the component  108  and an accommodation cavity delimiting side wall  112  of the stack  102  on the right-hand side has a width, D, being larger than another gap  129  between another side wall  110  of the component  108  and another accommodation cavity delimiting side wall  112  of the stack  102  on the left-hand side which has a width, d (where d&lt;D). For instance, the size D may be 500 μm, whereas the size d may be 75 μm. 
     Referring to  FIG.  5   , a further electrically insulating layer structure  106  (here embodied as a prepreg sheet made of low-flow material or no-flow material) and a further electrically conductive layer structure  104  (here embodied as a further copper foil) are attached to an upper main surface of the structure shown in  FIG.  4   , i.e., to a surface facing away from the temporary carrier  130 . The low-flow prepreg or no-flow prepreg of which the said electrically insulating layer structure  106  is made ensures that substantially no resin re-melts and flows into the gap  126  during a lamination procedure. Thus, the two additionally applied layer structures  106 ,  104  may be connected with the structure shown in  FIG.  4    by lamination, i.e., the application of pressure and heat, without the risk that resin flows into gap  126  and covers side wall  110  of component  108  there. As a result, in particular the gap  126  remains open even during lamination due to the use of low-flow prepreg or no-flow prepreg, which significantly simplifies exposing side wall  110  of the component  108  later (see  FIG.  8   ). 
     Referring to  FIG.  6   , a structure is shown which is obtained by firstly removing the temporary carrier  130  of  FIG.  5    after the described lamination procedure, and by secondly carrying out a further lamination procedure at a bottom side. More specifically, the temporary carrier  130  is no longer needed to provide mechanical support after the described first lamination procedure during which the low-flow or no-flow resin material of the further electrically insulating layer structure  106  has been hardened. Consequently, the temporary carrier  130  may be removed, for instance may be peeled off from the rest of the structure shown in  FIG.  5   . Thereafter, a further electrically insulating layer structure  106  (preferably made of low-flow prepreg or no-flow prepreg as well) and a further electrically conductive layer structure  104  (for example a further copper foil) may be laminated to a lower main surface of the structure shown in  FIG.  5    after removal of the temporary carrier  130 . Due to the use of low-flow prepreg or no-flow prepreg for the electrically insulating layer structures  106  above and beneath the component  108  and the gap  126 , a hollow space  183  remains in an interior of the structure shown in  FIG.  6    and allows keeping side wall  110  of component  108  free of resin material. 
     Referring to  FIG.  7   , schematically shown milling tool  121  may operate on the structure shown in  FIG.  6    and may cut away a portion of the layer stack on the right-hand side of the milling tool  121  in  FIG.  7    by milling through the gap  126  or hollow space  183 . 
     Referring to  FIG.  8   , the material of the stack  102  on the right-hand side of milling tool  121  in  FIG.  7    has been removed to thereby expose the side wall  110  of the component  108  with regard to an environment of the component carrier  100 . 
     When the component  108  is for instance embodied as laser diode, light can be emitted via the exposed side wall  110  to the environment. When the component  108  is for instance embodied as photodiode, light impinging on the exposed side wall  110  from an environment may be detected by the component  108 . When the component  108  is for instance a chemical sensor, a chemical in an environment of the exposed side wall  110  can be detected by the component  108 . 
     As a result of the described manufacturing procedure, the PCB type plate-shaped laminated component carrier  100  according to  FIG.  8    is obtained which comprises the stack  102  comprising multiple electrically conductive layer structures  104  and multiple electrically insulating layer structures  106  as well as the component  108  embedded in the stack  102 . The side wall  110  of the component  108  is exposed with regard to an environment of the component carrier  100  so as to be functionally coupleable with the environment of the component carrier  100 . According to  FIG.  8   , the exposed side wall  110  of the component  108  and a side wall  133  of the stack  102  are aligned to form a substantially continuous side wall  110  of the component carrier  100  extending substantially vertically. While one main surface  120  of the cuboid component  108  is exposed at side wall  110 , the other five main surfaces of this component  108  are covered by component carrier material of the stack  102  so as to be properly mechanically and electrically secured and protected. 
       FIG.  9    to  FIG.  12    illustrate cross-sectional views of structures obtained during manufacturing a component carrier  100  according to another exemplary embodiment. This embodiment is similar to the embodiments of the component carriers  100  of  FIG.  2    and  FIG.  3   . 
     Referring to  FIG.  9   , a structure similar to that shown in  FIG.  4    is formed. 
     In order to obtain the structure shown in  FIG.  10   , the gap  126  on the right-hand side of  FIG.  9    spacing the component  108  with regard to an accommodation cavity delimiting side wall  112  of the stack  102  is filled with a removable sacrificial material  128 . For instance, the sacrificial material  128  may be embodied as a release structure with non-adhesive properties with regard to the material of the component  108 . Such a release structure may for instance be a waxy component (which may be based on calcium stearate) or a PTFE-based material which can be applied in the form of a paste by using a wiper (not shown). The release structure may have the property to be non-adhesive with regard to both component material and component carrier material, in particular copper, epoxy resin, reinforcing glass fibers, and silicon. If desired or required, the sacrificial material  128  may be cured after insertion into gap  126 , for instance by a thermal treatment, by a chemical treatment and/or by applying mechanical pressure. 
     After having filled the cavity  126  with the sacrificial material  128 , a dielectric sheet as further electrically insulating layer structure  106  (here embodied as at least partially uncured material, for instance a prepreg sheet) and a further electrically conductive layer structure  104  (here embodied as a further copper foil) are attached to an upper main surface of the structure shown in  FIG.  9   , i.e., to a surface facing away from the temporary carrier  130 . In particular, the “at least partially uncured material” may comprise or consist of B-stage material and/or A-stage material. By providing the layer stack with prepreg or any other B-stage material, at least a portion of the layer stack may re-melt during lamination so that resin (or the like) may flow for interconnecting the various elements and for closing gaps or voids and may therefore contribute to a stable intrinsic interconnection within the component carrier  100  being manufactured. Subsequently, the two additionally applied layer structures  106 ,  104  may be connected with the structure shown in  FIG.  9    by lamination, i.e., the application of pressure and heat. While resin of the at least partially uncured material of the electrically insulating layer structure  106  may flow in gap  129  and may at least partially fill the latter during lamination, such flowable resin material will not move into gap  126  because gap  126  has already been filled by the sacrificial material  128 . This advantageously also keeps the side wall  110  of the component  108  covered by sacrificial material  128  free of resin material. 
     Referring to  FIG.  11   , a structure is shown which is obtained by firstly removing the temporary carrier  130  of  FIG.  9    after the described lamination procedure, and by secondly carrying out a further lamination procedure from a bottom side. More specifically, the temporary carrier  130  is no longer needed to provide mechanical support after the described first lamination procedure during which the previously at least partially uncured material of the further electrically insulating layer structure  106  has become hardened. Secondly, a further electrically insulating layer structure  106  and a further electrically conductive layer structure  104  are laminated onto the structure shown in  FIG.  10    (without temporary carrier  130 ) from a bottom side, to thereby obtain a symmetric configuration in a vertical direction. 
     Referring to  FIG.  12   , a portion of the obtained structure on the right-hand side of the component  108  is then removed by laser cutting, as indicated schematically by reference numeral  125 . A laser cutting line is oriented to extend vertically through the sacrificial material  128 . Advantageously, the laser process has a relatively high tolerance or does not need to be carried out with high spatial accuracy, since the relatively large width, D, of the gap  126  filled with the sacrificial material  128  defines the allowed tolerance. 
     The result of the laser cutting procedure will be a component carrier  100  having substantially an appearance as shown in  FIG.  8   . In order to obtain such a component carrier  100 , the sacrificial material  128  exposed after laser cutting is removed (for instance by stripping) to thereby expose the side wall  110 . Such a removal process is very simple due to the intentionally poor adhesion between the sacrificial material  126  on the one hand and the component  108  and component carrier material  102  on the other hand. 
     In another embodiment, the procedure described referring to  FIG.  9    to  FIG.  12    may be carried out in a corresponding way, however substituting the release paste material by other material for sacrificial structure  128 , preferably a water-soluble material such as a salt. When arriving at a structure corresponding to  FIG.  12   , this water-soluble material may be removed by supplying water, to thereby expose side wall  110  of component  108 . 
       FIG.  13    and  FIG.  14    illustrate a cross-sectional view and a plan view of a component carrier  100  according to an exemplary embodiment.  FIG.  14    shows a cutting line  141  along which the illustration of  FIG.  14    is to be cut to arrive at the cross-sectional view of  FIG.  13   . According to  FIG.  13    and  FIG.  14   , a slit-shaped access recess  114  contributing to exposing the side wall  110  extends from upper main surface  116  of the component carrier  100  to be manufactured up to a lower main surface  118  thereof. As can be taken from  FIG.  14   , the slit has a length L being larger than a width W thereof. The length L direction corresponds to a direction extending parallel to the side wall  110  of the component  108 , whereas the width W direction corresponds to a direction extending perpendicular to the side wall  110  of the component  108 . In the shown embodiment, the access recess  114  is configured as a through-hole extending through the entire stack  102 . According to  FIG.  13    and  FIG.  14   , sacrificial material  128  is again foreseen as a selectively removable spacer between side wall  110  of component  108  and cavity delimiting side wall  112  of stack  102 . However, in other embodiments in which a side wall  110  of component  108  is selectively exposed by a slit cut, the sacrificial material  128  may also be omitted (as in  FIG.  1   ,  FIG.  4    to  FIG.  8   ). When sacrificial material  128  is however foreseen, the sacrificial material  128  may be removed selectively after having formed the slit-shaped access recess  114  (for instance by directing water through the slit-shaped access recess  114  for removing water-soluble sacrificial material  128 ). It is also possible that at least part of the sacrificial material  128  is already removed during slit formation. In order to relax the accuracy requirements for forming the slit-shaped access recess  114  (for instance by milling or laser cutting), it is possible also according to  FIG.  13    and  FIG.  14    that the component  108  is arranged laterally asymmetrically in accommodation cavity  122  of the stack  102  with different distances d&lt;D with regard to opposing accommodation cavity delimiting side walls  112  of the stack  102 . The distance, D, at the side where the formation of the slit-shaped access recess  114  occurs is preferably larger than the distance, d, on the other side. 
       FIG.  15    illustrates a cross-sectional view of a component carrier  100  according to another exemplary embodiment. According to the embodiment of  FIG.  15   , a lateral access recess  114  extending into the stack  102  and exposing the side wall  110  of component  108  extends from a lateral side wall  133  of the stack  102  up to the side wall  110  of the component  108 . In  FIG.  15   , the access recess  114  is configured as a blind hole. 
     According to  FIG.  15   , a further component  124 , which is here configured as a light guide or optical fiber, is inserted into the blind hole type access recess  114 . When the component  108  is for instance embodied as a light detecting element (for instance a photodiode), electromagnetic radiation  143  propagating along the component  124  up to the exposed side wall  110  of the component  108  can be detected by component  108 . When the component  108  is however embodied as a light emitting element (for instance a laser diode), electromagnetic radiation  145  can be injected into the optical fiber for propagation along the component  124  via the exposed side wall  110  of the component  108 . Thus, the component carrier  100  of  FIG.  15    may for instance be used for optoelectronic data transmission. 
       FIG.  16    illustrates a cross-sectional view of a component carrier  100  according to still another exemplary embodiment. According to  FIG.  16   , slit-shaped access recess  114  is embodied as a blind hole exposing two opposing side walls  110  of a component  108  and a further component  124  both embedded in the same component carrier  100 . Recess  114  spaces components  108 ,  124  and simultaneously enables wireless data communication by transmission of electromagnetic radiation  147  (such as infrared radiation, optical light, radiofrequency (RF) radiation, etc.) between the exposed side walls  110  of the components  108 ,  124  via an air gap provided by access recess  114 . Thus, the component  108  and the further component  124  being both embedded in the stack  102  are communicatively coupled for wireless data communication via the access recess  114 . For instance the component  108  may be an electromagnetic radiation emitter and the further component  124  may be an electromagnetic radiation detector. 
     In contrast to  FIG.  1    to  FIG.  3   , the side walls  110  of the components  108 ,  124  are mutually exposed in an interior of the component carrier  100  so that the side walls  110  form part of an interior (rather than exterior) lateral side wall of the component carrier  100 . 
       FIG.  17    to  FIG.  20    illustrate cross-sectional views of structures obtained during manufacturing a component carrier  100  according to another exemplary embodiment. 
     A structure shown in  FIG.  17    is obtained by forming a first cavity portion  151  in stack  102 , for instance as a through hole in a fully cured core. A temporary carrier  130 , such as a sticky tape, is attached to a lower main surface of the stack  102  and closes the through hole at the bottom side. Subsequently, the first cavity portion  151  is filled with sacrificial material  128  such as release material. If desired or required, the sacrificial material  128  may then be cured. Thereafter, temporary carrier  130  may be removed. 
     A structure shown in  FIG.  18    is obtained by subsequently forming a second cavity portion  153  as a further through hole in the structure according to  FIG.  17    without temporary carrier  130 . The second cavity portion  153  is formed so as to laterally overlap with the first cavity portion  151 . As a result, part of the sacrificial material  128  is removed when forming the second cavity portion  153 . 
     A structure shown in  FIG.  19    is obtained by connecting a further temporary carrier  130 ′ to a lower main surface of the stack  102 , to a lower main surface of the remaining sacrificial material  128  and to close a bottom of the through hole constituting the second cavity portion  153 . Thereafter, component  108  is inserted into the second cavity portion  153  so that the first cavity portion  151  filled with the sacrificial material  128  and the second cavity portion  153  accommodating the component  108  together constitute a common accommodation cavity  122  for accommodating the component  108  and the sacrificial material  128 . 
     A structure shown in  FIG.  20    is obtained by laminating a further portion of stack  102  onto an upper main surface of the structure shown in  FIG.  19   . Thereafter, the further temporary carrier  130 ′ may be removed from a bottom surface of the obtained structure. After this, yet another portion of stack  102  can be laminated on a lower main surface of the obtained structure. As indicated by a separation line  155 , the obtained structure may be separated then by a vertical cut, which can for instance be accomplished by a laser treatment or mechanically. After removing the remaining portion of the sacrificial material  128 , the side wall  110  of component  108  is exposed and a component carrier  100  according to an exemplary embodiment is obtained. 
     The embodiment of  FIG.  17    to  FIG.  20    has the advantage that there is substantially no limitation concerning the horizontal width of the first cavity portion  151  which simplifies the supply of the sacrificial material  128  into the first cavity portion  151 . 
       FIG.  21    illustrates a cross-sectional view of three component carriers  100  spaced side-by-side according to another exemplary embodiment. 
     In the embodiment of  FIG.  21   , the juxtaposed component carriers  100  are spaced with regard to each other by respective gaps  197 . Lateral surface portions of multiple embedded components  108  of the component carriers  100  are exposed. As can be taken from  FIG.  21   , each of the shown component carriers  100  comprises, as respective component  108 , at least one sender  108   a  and at least one receiver  108   b.    
     By arranging the component carriers  100  one next to the other with mutually aligned sender  108   a  of one component carrier  100  emitting electromagnetic radiation  199  and receiver  100   b  of another component carrier  100  receiving the electromagnetic radiation  199 , the arrangement according to  FIG.  21    is appropriate for applications such as Near Field Communication (NFC). A communication according to another communication protocol is possible. For instance, the communication may be accomplished by infrared communication, Bluetooth®, etc. The component carrier  100  being arranged, according to  FIG.  21   , in the middle between the other two component carriers  100  has a respective pair of sender  108   a  and receiver  108   b  on each of the two opposing main surfaces thereof. Thus, the component carrier  100  in the middle sandwiched by the other two component carriers  100  may communicate with both other component carriers  100 . Bluetooth® is a registered trademark of Bluetooth Sig, Inc. of Kirkland, Wash., U.S.A. 
       FIG.  22    illustrates an example showing a light-emitting diode  200  emitting light  202  through optically transparent material  204 . 
     According to  FIG.  22   , the light-emitting diode  200  is encapsulated in an encapsulant  206  and emits the light  202  with a cross-sectional area A into the transparent material  204 . Due to a rough surface of the transparent material  204 , light diffraction occurs which increases the cross-sectional area A′ of the light leaving the transparent material  204  at an air interface. This undesired phenomenon is promoted by the pronounced surface roughness of the transparent material  204 . 
       FIG.  23    to  FIG.  25    show different structures obtained during manufacturing a component carrier  100  according to an exemplary embodiment which is shown, in operation, in  FIG.  26   . 
     Referring to  FIG.  23   , a component  108  is embedded in a stack  102  composed of electrically conductive layer structures  104  as well as electrically insulating layer structures  106 . In the shown embodiment, the component  108  comprises an electromagnetic radiation emitting member  108 ′ (such as a light-emitting diode, for instance embodied as laser die) configured for emitting light as electromagnetic radiation  145 . The electromagnetic radiation emitting member  108 ′ is electrically coupled with the electrically conductive layer structures  104 . The electromagnetic radiation emitting member  108 ′ is circumferentially covered by a transparent material  108 ″. The transparent material  108 ″ is preferably a fiber free resin which does not disturb propagation of electromagnetic radiation  145  (compare  FIG.  26   ) through the transparent material  108 ″. Thus,  FIG.  23    shows an embedded component  108  in a panel. 
     Referring to  FIG.  24   , material of the stack  102  is removed by a cutting procedure, as described above, to thereby expose side wall  110  of the component  108 , more precisely the side wall  110  of the transparent material  108 ″ of the component  108 . During operation of the component carrier  100  being manufactured, electromagnetic radiation  145  emitted by the electromagnetic radiation emitter member  108 ′ propagates through the transparent material  108 ″ and leaves the component carrier  100  via the exposed side wall  110 . However, as a result of the cutting procedure, the exposed side wall  110  has a pronounced surface roughness, as indicated schematically by reference numeral  210 . Hence,  FIG.  24    shows the result of a card cutting procedure, after which the side surface of the transparent material  108 ″ remains rough. 
     Referring to  FIG.  25   , the exposed rough side wall  110  of the transparent material  108 ″ is polished, for instance mechanically or chemically. Hence, the structure shown in  FIG.  24    may be made subject of a lateral polishing procedure which smoothes the side wall surface of the transparent material  108 ″ after the polishing process. As a result, the emitted electromagnetic radiation  145  propagates as a parallel narrow beam through the transparent material  108 ″ and the side wall  110  without being substantially spatially widened, see  FIG.  26   . 
     The embodiment according to  FIG.  26    has the advantage that it is possible to embed a laser diode as electromagnetic radiation emitting member  108 ′ in the PCB type component carrier  100 , and at the same time use the transparent window in the stack  102  for propagation of the laser beam as electromagnetic radiation  145 . As can be taken from  FIG.  26   , the portion of the transparent material  108 ″ between the side wall of the electromagnetic radiation emitting member  108 ′ and the lateral side wall of the component carrier  100  forms part of an optical path along which the electromagnetic radiation  145  propagates. Therefore, the component carrier  100  according to  FIG.  26    can be used for optical communication or projection, for example of visible light or infrared radiation, in particular embodied as laser beam. The electromagnetic radiation  145  is emitted by the component  108  or can be received and detected by the component  108 . Preferably, the transparent material  108 ″ is free of bubbles, fibers, fabrics, etc. and has absorption properties allowing light passing without significant losses. As can be taken from  FIG.  26   , the transparent material  108 ″ remains in the lateral opening of the component carrier  100 . Although not shown in the figure, a photodiode may be installed in the back of the laser diode. A person skilled in the art of laser technology will understand the installation of the photodiode in the build up with the methods mentioned in the above description. As an alternative to the embodiment according to  FIG.  26   , it is also possible to keep the lateral opening of the component carrier  100  (filled with the transparent material  108 ″ according to  FIG.  26   ) empty or to remove transparent material  108 ″ out of such a lateral opening, similar as in  FIG.  15   . 
       FIG.  27    illustrates spectacles  220  according to an exemplary embodiment comprising the component carrier  100  shown in  FIG.  26   . 
     Descriptively speaking,  FIG.  27    schematically illustrates a left half of the spectacles  220  (see symmetry axis  212 ). As can be taken from  FIG.  27   , the component carrier  100  according to  FIG.  26    is assembled within a housing  216  which may be connected to an arm or a frame of the spectacles  220  (see reference numeral  218 ). As also shown in  FIG.  27   , the spectacles  200  additionally comprise a screen  230  onto which a user wearing the spectacles  220  looks with his eyes  240 . The light transmitted as the electromagnetic radiation  145  from the electromagnetic radiation emitting member  108 ′ of the component  108  embedded within the component carrier  100  is displayed on the screen  230  and can be seen by the user when wearing and looking through the spectacles  220 . The screen  230  can have micro-actuators and micro-mirrors for means of light deflection and image formation. Colors can be formed with three lasers in red, green, and blue to form the RGB system of colors. 
     It should be noted that the term “comprising” does not exclude other elements or steps and the article “a” or “an” does not exclude a plurality. Also, elements described in association with different embodiments may be combined. 
     It should be further understood that when the phrase “at least one of A and B” is included in a claim, where the labels A and B represent a recitation of limitations or features, the phrase “at least one of A and B” means at least one of A or B. It should be further understood that “at least one of A or B” includes the limitations or features of: A alone; B alone; any positive whole number of A alone; any positive whole number of B alone; and any combination of a positive whole number of A with a positive whole number of B. 
     Implementation is not limited to the preferred embodiments shown in the figures and described above. Instead, a multiplicity of variants is possible which variants use the solutions shown and the principle according to embodiments of the invention even in the case of fundamentally different embodiments.