CN219678768U

CN219678768U - Component carrier

Info

Publication number: CN219678768U
Application number: CN202320220058.1U
Authority: CN
Inventors: 塞巴斯蒂安·萨特勒; 海因茨·普凡德; 克劳迪娅·埃布纳
Original assignee: AT&S Austria Technologie und Systemtechnik AG
Current assignee: AT&S Austria Technologie und Systemtechnik AG
Priority date: 2022-01-25
Filing date: 2023-01-30
Publication date: 2023-09-12
Anticipated expiration: 2033-01-30
Also published as: DE202022100414U1

Abstract

The utility model provides a component carrier (100), the component carrier (100) comprising: a stack (102), the stack (102) comprising at least one electrically insulating layer structure (104), a first electrically conductive layer structure (106) and a second electrically conductive layer structure (108); an air cavity (110) located in the stack (102), the air cavity (110) being configured to facilitate transmission of radio frequency signals with the first electrically conductive layer structure (106) and the second electrically conductive layer structure (108); and a protective structure (112), the protective structure (112) covering at least a portion of the first electrically conductive layer structure (106) located at a boundary (114) of the air cavity (110).

Description

Component carrier

Technical Field

The present utility model relates to component carriers.

Background

With increasing product functions of component carriers equipped with one or more electronic components, increasing miniaturization of such electronic components, and increasing number of electronic components mounted on component carriers such as printed circuit boards, increasingly powerful array components or packages having a plurality of electronic components are employed, which have a plurality of contact portions or connection portions with smaller and smaller pitches between the contact portions or connection portions. Removal of heat generated by these electronic components and the component carriers themselves during operation is becoming an increasingly greater problem. At the same time, the component carrier should be mechanically strong and electrically reliable so as to operate even under harsh conditions.

Furthermore, the transmission of high frequency signals propagating along the wiring structure and/or along at least one cavity of the component carrier may be a challenge. On the one hand, the transmission artefacts can greatly reduce the overall performance of component carriers with high frequency functions. At the same time, providing high frequency functions using component carriers such as printed circuit boards may introduce undesirable phenomena such as degradation of signal quality.

Disclosure of Invention

The object of the utility model is to provide a component carrier with a high performance and a high signal quality in terms of high-frequency signal transmission and/or radiation.

In order to achieve the above object, a component carrier according to the utility model is provided.

According to an exemplary embodiment of the present utility model, there is provided a component carrier, wherein the component carrier comprises: a stack comprising at least one electrically insulating layer structure, a first electrically conductive layer structure and a second electrically conductive layer structure; an air cavity in the stack, the air cavity configured to facilitate transmission of radio frequency signals with the first electrically-conductive layer structure and the second electrically-conductive layer structure; and a protective structure covering at least a portion of the first electrically conductive layer structure at a boundary (or edge) of the air cavity.

According to another exemplary embodiment of the present utility model, a component carrier having the above-mentioned features is used for Radio Frequency (RF) or high frequency applications, in particular for conducting radio frequency signals, more in particular for conducting radio frequency signals having a frequency higher than 1 GHz.

In the context of the present utility model, the term "component carrier" may particularly denote any support structure capable of accommodating one or more components thereon and/or therein for providing mechanical support and/or electrical connection. In other words, the component carrier may be configured as a mechanical and/or electrical carrier for the component. In particular, the component carrier may be one of a printed circuit board, an organic interposer, and an IC (integrated circuit) substrate. The component carrier may also be a hybrid plate combining different ones of the above-mentioned types of component carriers.

In the context of the present utility model, the term "stack" may particularly denote an arrangement of a plurality of planar layer structures mounted one above the other parallel to each other.

In the context of the present utility model, the term "layer structure" may particularly denote a continuous layer, a patterned layer or a plurality of discontinuous islands (islands) in the same plane.

In the context of the present application, the term "air cavity" may particularly denote a hollow structure that may contain waves, such as electromagnetic waves. For example, the air cavity may be a hollow recess inside the layer stack of the component carrier, which hollow recess may be used for carrying high frequency radio waves. For example, the recess used as the radio frequency cavity may be rectangular or circular in cross-section. The air cavity may be hollow, e.g. the air cavity may be filled with air. The shape and size of the air cavity may be adjusted according to the signal frequency. Furthermore, the air cavity may be tuned to meet the resonance conditions for the signal. Furthermore, the position of the air cavity may be related to the area where the electromagnetic field is strongest. Thus, the air cavity may be placed under a feed (in particular strip) line or under an antenna structure such as a patch antenna. By removing material under the strip line or feed line, losses can be reduced or even minimized, as the material that caused the losses is removed. The air cavities may be channels and one or more cavities may be implemented. Furthermore, the sidewalls may optionally be covered with copper to further reduce losses. However, the air cavity may not be completely metallized and thus may involve other boundaries for the signal (such as etched structures like striplines or microstrip lines, microstrip antennas, etc.). Only the air cavities may be placed for the purpose of exchanging the Dk/Df of the matrix material with the Dk/Df of air. The placement of this air cavity underneath a region of high concentration of the electromagnetic field, such as a microstrip line or microstrip antenna, may have the greatest effect.

In the context of the present application, the term "the air cavity located in the stack is configured to facilitate transmission of radio frequency signals together with the first and second electrically conductive layer structures" may particularly denote a specific configuration between the air cavity and the two electrically conductive layer structures described above, according to which configuration radio frequency signals (particularly frequencies above 1GHz, particularly above 30 GHz) may be electromagnetically coupled and transmitted within the component carrier by cooperation between the electrically conductive layer structures and the air cavity. In particular, the geometry of the air cavity and the geometry of the electrically conductive layer may be arranged in a matched manner to transmit electrical or electromagnetic high frequency signals. In this case, it may be advantageous to arrange the electrically conductive layer structure and the air cavities such that they at least partially overlap in the vertical viewing direction. For example, one of the electrically-conductive layer structures is configured to act as a ground or reference layer, while the other electrically-conductive layer structure is configured to act as an antenna for coupling and/or separating electromagnetic signals that also propagate along the air cavity.

In the context of the present application, the term "protective structure" may particularly denote a physical structure (such as a layer or coating) configured to inhibit the transfer of corrosive or humid media from the hollow cavity through the protective structure to the first electrically conductive layer structure. Thus, the protective structure may be a barrier structure that is impermeable to oxidizing or corrosive agents and/or that may inhibit migration. Thus, the protective structure may be a corrosion and/or oxidation resistant protective structure. For example, the protective structure may be formed as a single unitary structure, or as an assembly of two or more discrete structures.

In the context of the present utility model, the term "protective structure covers the first electrically conductive layer structure located at the boundary of the air cavity" may particularly denote: the protective structure may be formed on at least the following surface areas of the first electrically conductive layer structure: this surface area would otherwise (i.e. without protective structure) form part of the physical edge (such as a wall or any other solid-gas junction) of the hollow volume defining the cavity. However, the protective structure may also be applied partly, for example only on the structured conductive layer in the cavity. In other words, the protective structure may be disposed on the first electrically conductive layer structure such that the protective structure spaces the first electrically conductive layer structure relative to the hollow volume of the cavity.

According to an exemplary embodiment of the utility model, a component carrier, such as a printed circuit board, PCB, is provided, the component carrier comprising a hollow cavity configured as a radio frequency structure incorporated in a (preferably laminated) laminate for conducting and/or processing high frequency signals propagating through the component carrier. Advantageously, electrically conductive layer structures that may functionally facilitate Radio Frequency (RF) signal propagation and may spatially partially define at least a portion of a cavity may be covered by (e.g., dielectric) protective structures (e.g., layers) located in (e.g., ventilated) cavity-based RF structures. Such a protective structure may prevent the electrically conductive layer structure from undesirably (e.g., chemically) interacting with the environment or medium in the air cavity. Such interactions with moisture, oxidizing media and/or corrosive chemicals may be prevented, for example, by passivating the electrically conductive layer structure by a protective structure. This can ensure in a simple manner that the radio frequency structure supported by the air cavity is reliably produced. By ensuring the functional integrity of the electrically conductive layer structure defining at least a portion of the hollow cavity, the reliability of the component carrier, the proper high frequency performance and usability of the component carrier can be ensured even under severe conditions.

Detailed description of exemplary embodiments

In the following, further exemplary embodiments of the component carrier and a method of use will be described.

Hereinafter, materials that can be used as the protective layer will be summarized in non-exhaustive manner. The protective layer may be polymer based, for example based on epoxy (such as FR 4) or polyimide. Preferably, non-polar and hydrophobic polymers such as teflon can be used to reduce or even minimize moisture absorption. In addition, non-polar polymers may be used to reduce the occurrence of losses. The more polar the dielectric material, the more signal may be lost. The protective layer may be formed by surface treatment to improve adhesion (e.g., one or more tie films). The corresponding formulation of the protective layer may be based on silane or molecules exhibiting a conjugated pi system. These molecules can attach to copper and can prevent copper from being oxidized. The protective layer may be metal-based, such as based on a metal-based surface treatment referred to elsewhere in this specification. Preferably, the treatments are nickel-free. The protective layer may be ceramic-based (non-electrically conductive). Thinner glass sheets may also be implemented on the electrically conductive layer. The protective layer may prevent the surface from being oxidized. At higher frequencies, signal loss may have a significant impact on performance. Oxide layers on the surface may lead to signal losses. In addition, oxidized surfaces may also introduce ion migration because the polarity of the surface may be different from the material within. Therefore, the protective layer can not only prevent the surface from being oxidized, but also reduce the incidence of ion migration. Furthermore, the protective layer may be configured so as not to cause significant signal loss.

In an embodiment, at least one of the at least one electrically insulating layer structure comprises or consists of a lower DF and/or a lower DK dielectric solid. Lower DF materials have lower imaginary parts of dielectric constants. The imaginary part of the dielectric constant determines the loss. Configuring at least one of the electrically insulating layer structures at least partially as a lower DF dielectric solid may keep losses of the signal small. For example, a suitable lower DK and lower DF dielectric solid may be ceramic or RO3003 supplied by Rogowski ^TM A material.

In an embodiment, the air cavity is substantially cube-shaped. Such cube-shaped void areas in the interior of the laminated stack of component carriers may provide powerful radio frequency related functions. For example, the cube-shaped cavity may have a side length in the range of 1 to 20 millimeters, in particular in the range of 2 to 10 millimeters. However, those skilled in the art will appreciate that the exact dimensions may depend on the frequency applied.

In an embodiment, the air cavity is a longitudinal channel. Such longitudinal channels may have the following lengths: the length is at least twice, in particular at least three times, the width and the height. The high frequency signal may propagate along such a channel cavity in a well-defined manner.

The component carrier may include one or more air cavities. When a plurality of air cavities are implemented in the component carrier, each of the cavities may have a protective structure covering a respective electrically conductive layer structure defining the respective air cavity.

In an embodiment, the portion of the first electrically conductive layer structure extends along the bottom of the air cavity. For example, the first electrically conductive layer structure may be a horizontal layer that is separated from the hollow cavity only by a protective structure that acts as a passivation spacer.

In an embodiment, the protective structure is configured to protect the first electrically-conductive layer structure from at least one of corrosion and oxidation of the first electrically-conductive layer structure. Oxidation may represent an increase in the electron loss or oxidation state of atoms, ions or molecules of the first electrically conductive layer structure. For example, oxidation may be caused by the reaction of the material of the first electrically conductive layer structure with oxygen. In particular, corrosion may represent a process of converting a metal of the first electrically conductive layer structure into a chemically more stable form such as a hydroxide, carbonate or sulfide. Thus, corrosion can lead to progressive destruction of the metal or alloy by chemical and/or electrochemical reactions with the environment. Corresponding disadvantages may occur in terms of oxidation. Illustratively, a charged or oxidized surface may cause a gradient in ion migration due to mass transport. When the first electrically conductive layer structure located at the boundary of the air cavity is oxidized or corroded, the high frequency function of the first electrically conductive layer structure may be deteriorated or damaged, which may result in a reduction or loss of signal transmission quality. In particular, when vents are formed in the stack to ensure access to the air cavity from the outside, an oxidizing or corrosive medium, such as humid air or an oxidizing atmosphere, may enter the air cavity. Such a medium may cause oxidation or corrosion of the exposed metal structure in the form of the first electrically conductive layer structure (e.g. made of copper). The material of the protective structure may be selected to inhibit, prevent or make impossible corrosion and/or oxidation.

In an embodiment, the first electrically conductive layer structure is configured as a reference layer, for example as a ground layer. In particular, the ground layer or plane of the (in particular PCB-type) component carrier may be a larger area of the first electrically conductive layer structure (e.g. copper foil) in the stack or circuit board, which area may be connected to the power ground terminal and may serve as a return path for current from different components on the component carrier. Such a ground or reference layer may be covered by a protective structure to prevent the ground layer from being exposed within the hollow volume of the cavity. This may have the advantage of preventing long-term problems with the component carrier due to oxidation and/or corrosion.

In an embodiment, the second electrically conductive layer structure is configured as an antenna structure or as a part of an antenna structure. For example, the antenna structure may be planar. In the context of the present application, the term "antenna structure" may particularly denote the following electrically conductive structure: the electrically conductive structure is shaped, dimensioned to be capable of wirelessly receiving and/or wirelessly transmitting an electromagnetic radiation signal corresponding to an electrical or electromagnetic signal, which may be conducted along the electrically conductive wiring structure of the component carrier and may be coupled in or via the cavity. By such an antenna structure incorporated in or formed on top of the stack, high frequency signals may be coupled into or out of the cavity. However, the air cavity may also form part of the antenna.

In another embodiment, the antenna structure may be configured as a Dielectric Resonator Antenna (DRA). The dielectric resonator antenna may be a radio antenna used at microwave frequencies and higher, which is formed of various shapes of ceramic material blocks, dielectric resonators mounted on metal surfaces, ground planes. Radio waves may be introduced from the transmitter circuit into the interior of the resonator material and may bounce back and forth between the resonator walls, forming standing waves. The walls of the resonator may be partially transmissive to radio waves, allowing radio power to radiate into space.

In an embodiment, the second electrically conductive layer structure is provided at an outer surface of the stack above the air cavity. This ensures a proper electromagnetic coupling between the electronic periphery of the component carrier and the second electrically conductive layer structure, in particular configured as an antenna structure.

In an embodiment, the component carrier comprises one or more ventilation holes extending between the air cavity and the outside of the stack. Such at least one vent may be placed anywhere. For example, the vent holes may extend upward from the bottom of the PCB stack, downward from the top of the PCB stack, and/or inward from the sides of the PCB stack. Such vents, in terms of description, allow for the exchange of gas (in particular air) between the air cavity and the gaseous medium (in particular air) surrounding the component carrier. Advantageously, such vents prevent significant pressure differences (e.g., caused by temperature changes) from forming between the cavity and the environment of the component carrier, thereby inhibiting undesirable phenomena of the component carrier such as delamination or warping. However, the gas entering the air cavity from the outside may introduce an active medium into the air cavity, which may cause undesired chemical reactions with the exposed surface of the first electrically conductive layer structure, in particular when made of copper. Covering the exposed surface of the first electrically conductive layer structure with a protective structure may passivate the first electrically conductive layer structure, thereby ensuring higher performance radio frequency functions without creating artifacts due to oxidation or corrosion of the exposed metal within the cavity, even if one or more ventilation holes are provided.

In an embodiment, the protective structure comprises or consists of a dielectric material. Advantageously, such dielectric materials should be impermeable to corrosive or oxidizing media to properly protect the first electrically conductive layer structure.

Additionally or alternatively, the protective structure may comprise or consist of a metallic material. Preferably, such a metallic material should not significantly affect the radio frequency function of the component carrier, in particular of the cavity, such a metallic material should serve as a barrier against corrosion and oxidation medium with respect to the first electrically conductive layer structure, and such a metallic material should preferably be inert such that the metallic protective structure itself is not susceptible to oxidation or corrosion. For example, noble metals may be suitable for this purpose. Preferably, the protective structure may be formed using a metal surface treatment, as the metal surface treatment process is typically used in PCB manufacturers. Preferably, the metallic material should be nickel-free.

In an embodiment, the component carrier comprises at least one high frequency component surface mounted and/or embedded in the stack. In the context of the present application, the term "high frequency component" may particularly denote the following electronic components: the electronic component is configured to perform tasks that may be related to the processing and/or communication of radio frequency signals. Such radio or high frequency signals may be electrical or electromagnetic signals propagating along the wiring structure of the component carrier in a frequency range for communication with other signals. In particular, the Radio Frequency (RF) signal may have a frequency, for example, in the range between 3kHz and 300GHz, in particular in the range of 2GHz to 150 GHz. The high frequency component may have an integrated function in terms of high frequency signal generation, and/or high frequency signal processing, and/or high frequency signal transmission. For example, the high frequency component may be a semiconductor chip (e.g., an RFIC, radio frequency integrated circuit) configured for operation by a high frequency signal. For example, the high frequency component may provide a front-end function for performing front-end processing tasks for high frequency applications, particularly communication applications. In particular, such a front-end chip may comprise at least one filter (e.g. a high pass filter, a low pass filter and/or a band pass filter), a mixer for mixing signals and/or an ADC (analog to digital converter). Thus, the front-end chip may process the front-end signal, for example in the analog domain. Additionally or alternatively, the high frequency component may be used for impedance matching to ensure matching of the impedance of the front-end chip and the coupling element. In addition or alternatively, other functions of the high frequency component are also possible.

When the at least one high frequency component forms part of the component carrier, the at least one high frequency component may be electrically coupled with at least one of the first electrically conductive layer structure, the second electrically conductive layer structure and the air cavity.

In an embodiment, the component carrier is configured as at least one of a radio frequency application, a wireless application (in particular for 5G applications) and a radar application. More generally, an exemplary application of an exemplary embodiment of the present utility model may be a radio frequency component carrier such as a radar sensor, a component carrier for 5G, 6G, ioT (internet of things Internet of Things), or AIM products (e.g., 5G base station, automotive radar, etc.).

In an embodiment, the protective structure is a layer covering the bottom of the air cavity. Such a protective layer may extend horizontally along the horizontal bottom of the air cavity. Protective layers of this type can be incorporated into the component carrier by lamination. Alternatively, such layered protective structures may be deposited, printed or dispensed.

In an embodiment, the protective structure is configured as a coating covering at least a portion of at least the side walls of the air cavity and optionally also the horizontal surfaces defining the hollow cavity. For example, such a coating may cover the bottom surface and the vertical sidewalls of the air cavity. This may increase the degree of freedom in choosing an appropriate manufacturing process to form the protective structure.

The protective structure may be made of various materials, as will be described below.

In an embodiment, the protective structure forms part of at least one electrically insulating layer structure of the stack. Thus, the protective structure may be associated with one or more layer structures of the laminated layer stack of the component carrier. This ensures a uniform material composition of the component carrier. For example, the protective structure comprises or consists of a resin (in particular an epoxy resin), optionally a reinforcing structure (in particular glass fibres or glass spheres). For example, the protective structure may be made of FR4 or prepreg of the following thickness: this thickness ensures proper protection of the underlying first electrically conductive layer structure from oxidation and corrosion. Preferably, the protective structure may comprise a hydrophobic and a non-polar polymer. However, bonding films, surface treatments, ceramics and other polymer-based protective layers are also possible.

In addition, the protective structure may include polytetrafluoroethylene (PTFE, also denoted as) Or polytetrafluoroethylene (PTFE, also denoted +.>) The composition is formed.

In an embodiment, the protective structure is a surface treatment. Such surface treatments may be electrically conductive covering materials on exposed electrically conductive layer structures (such as pads, conductive traces, etc., particularly including or consisting of copper) located on the surface of the component carrier. According to the described embodiments of the utility model, the surface treatment may also be applied to the first electrically conductive layer structure defining the air cavity. This makes the formation of the protective structure very simple, since the protective structure can be realized by a surface treatment stage used during the manufacture of the component carrier, such as a printed circuit board. Advantageously, the surface treatment also has a passivating or barrier effect against corrosive and oxidizing media and is therefore well suited for defining the hollow volume of the cavity.

In an embodiment, the protective structure is an adhesion promoter that promotes adhesion of the first electrically conductive layer structure to the stack. Such adhesion promoters may, for example, comprise silane, and may be deposited as a thinner layer on the first electrically conductive layer structure and on one or more other layer structures of the stack. This can improve interlayer adhesion of the obtained structure, and thus can suppress undesirable phenomena such as delamination in the component carrier that has been manufactured. On the first electrically conductive layer structure exposed at the air cavity, the adhesion promoter may also act as a barrier to corrosive or oxidizing media in the hollow volume of the cavity.

In an embodiment, the component carrier is used for high frequency applications above 1GHz, in particular above 3 GHz. In particular, for such higher frequencies, the signal transmission is particularly sensitive to artefacts (artifacts) caused by surface roughness, taking into account skin effects, according to which the high-frequency signals propagate only along the thinner epidermis of the wiring structure. Since the protective structure may protect the first electrically conductive layer structure from corrosion and/or oxidation, the protective structure may also prevent an increase in surface roughness caused by oxidation and/or corrosion. Thus, a higher performance of the component carrier can be ensured, which allows for lower losses of signal transmission even with such higher frequency values.

In an embodiment, the component carrier comprises a stack of at least one electrically insulating layer structure and at least one electrically conducting layer structure. For example, the component carrier may be a laminate of the above-described electrically insulating layer structure and electrically conductive layer structure, in particular formed by applying mechanical pressure and/or thermal energy. The stack may provide a plate-like component carrier that is capable of providing a large mounting surface for further components, but is very thin and compact.

In an embodiment, the component carrier is shaped as a plate. This contributes to a compact design, wherein the component carrier nevertheless provides a larger base for mounting components on the component carrier. In addition, in particular, a bare wafer, which is an example of an embedded electronic component, can be conveniently embedded in a thin plate such as a printed circuit board due to its small thickness.

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

In the context of the present application, the term "printed circuit board" (PCB) may particularly denote a board-like component carrier formed by laminating a plurality of electrically conductive layer structures with a plurality of electrically insulating layer structures, for example by applying pressure and/or by supplying thermal energy. As a preferred material for PCB technology, the electrically conductive layer structure is made of copper, whereas the electrically insulating layer structure may comprise resin and/or glass fibres, so-called prepreg or FR4 material. The electrically conductive layer structures may be connected to each other in a desired manner by forming holes through the laminate, for example by laser drilling or mechanical drilling, and by partially or completely filling the through holes with an electrically conductive material, in particular copper, thereby forming vias or any other through hole connections. The filled holes connect the entire stack (the through hole connections extending through multiple layers or the entire stack), or the filled holes connect at least two electrically conductive layers, called vias. Similarly, optical interconnects may be formed through the various layers of the stack to receive an electro-optic circuit board (EOCB). In addition to one or more components that may be embedded in a printed circuit board, the printed circuit board is typically configured to house the one or more components on one surface or both opposing surfaces of the board-like printed circuit board. The one or more components may be connected to the respective major surfaces by welding. The dielectric portion of the PCB may include a resin with reinforcing fibers, such as fiberglass.

In the context of the present application, the term "substrate" may particularly denote a smaller component carrier. The substrate may be a relatively small component carrier, relative to the PCB, on which one or more components may be mounted, and may serve as a connection medium between one or more chips and the further PCB. For example, the substrate may have substantially the same dimensions as the components (in particular electronic components) to be mounted on the substrate (e.g. in the case of Chip Scale Packages (CSPs)). More specifically, a substrate may be understood as a carrier for an electrical connector or electrical network as well as a component carrier comparable to a Printed Circuit Board (PCB) but having a rather high density of laterally and/or vertically arranged connectors. The lateral connectors are for example conductive paths, while the vertical connectors may be for example boreholes. These lateral and/or vertical connections are arranged within the base plate and may be used to provide electrical, thermal and/or mechanical connection of the accommodated components or the non-accommodated components (such as bare wafers), in particular IC chips, to the printed circuit board or to an intermediate printed circuit board. Thus, the term "substrate" also includes "IC substrate". The dielectric portion of the substrate may comprise a resin with reinforcing particles, such as reinforcing spheres, in particular glass spheres.

The substrate or interposer may include or consist of: at least one layer of glass, silicon, and/or photoimageable or dry etchable organic material such as an epoxy-based laminate (e.g., an epoxy-based laminate film), or a polymer composite (which may or may not include photosensitive and/or thermosensitive molecules) such as polyimide, polybenzoxazole.

In an embodiment, the at least one electrically insulating layer structure comprises at least one of: resins or polymers such as epoxy resins, cyanate ester resins, benzocyclobutene resins, bismaleimide triazine resins, polyphenyl derivatives (e.g., based on polyphenylene ether, PPE), polyimides (PI), polyamides (PA), liquid Crystal Polymers (LCP), polytetrafluoroethylene (PTFE), and/or combinations thereof. Reinforcing materials such as mesh, fibers, spheres or other types of filler particles, for example made of glass (multiple layer glass), may also be used to form the composite. Semi-cured resins, such as fibers impregnated with the above resins, combined with reinforcing agents are known as prepregs. These prepregs are generally named after the properties of the prepreg that describe the flame retardant properties of the prepreg, such as FR4 or FR5. While prepregs, particularly FR4, are generally preferred for rigid PCBs, other materials may be used, particularly epoxy-based laminates (such as laminates) or photoimageable dielectric materials. For high frequency applications, high frequency materials such as polytetrafluoroethylene, liquid crystal polymers, and/or cyanate ester resins may be preferred. In addition to these polymers, low Temperature Cofired Ceramics (LTCCs) or other low DK materials, very low or ultra low DK materials may be applied as electrical insulation structures in component carriers.

In an embodiment, the at least one electrically conductive layer structure comprises at least one of: copper, aluminum, nickel, silver, gold, palladium, tungsten, and magnesium. Although copper is generally preferred, other materials or coating variants thereof are also possible, in particular coated with superconducting materials or conducting polymers, such as graphene or poly (3, 4-ethylenedioxythiophene) (PEDOT), respectively.

At least one component may be selected from each of: non-electrically conductive inlay, electrical conductivityInlay (such as a metal inlay, preferably comprising copper or aluminum), a heat transfer unit (e.g. a heat pipe), a light guiding element (e.g. an optical waveguide or a light conductor connection), an electronic component or a combination thereof. The inlay may be, for example, a metal block with or without a coating of insulating material (IMS-inlay), which may be embedded or surface mounted for the purpose of promoting heat dissipation. Suitable materials are defined in terms of their thermal conductivity, which should be at least 2W/mK. Such materials are typically based on, but are not limited to, metals, metal oxides and/or ceramics, such as copper, aluminum oxide (Al ₂ O ₃ ) Or aluminum nitride (AlN). Other geometries with increased surface area are also often used in order to increase heat exchange capacity. Furthermore, the components may be active electronic components (with at least one p-n junction implemented), passive electronic components such as resistors, inductors, or capacitors, electronic chips, memory devices (e.g., DRAM or other data storage device), filters, integrated circuits (e.g., field Programmable Gate Array (FPGA), programmable Array Logic (PAL), general purpose array logic (GAL), and Complex Programmable Logic Device (CPLD)), signal processing components, power management components (e.g., field Effect Transistors (FETs), metal Oxide Semiconductor Field Effect Transistors (MOSFETs), complementary Metal Oxide Semiconductors (CMOS), junction Field Effect Transistors (JFETs), or insulated-gate field effect transistors (IGFETs), all based on semiconductor materials such as silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide (Ga) ₂ O ₃ ) Indium gallium arsenide (InGaAs), indium phosphide (InP), and/or any other suitable inorganic compound), optoelectronic interface elements, light emitting diodes, photocouplers, voltage converters (e.g., DC/DC converters or AC/DC converters), cryptographic components, transmitters and/or receivers, electromechanical converters, sensors, actuators, microelectromechanical systems (MEMS), microprocessors, capacitors, resistors, inductors, batteries, switches, cameras, antennas, logic chips, and energy harvesting units. However, other components may be embedded in the component carrier. For example, a magnetic element may be used as the member. Such magnetic elements may be permanent magnetic elements (e.g., ferromagnetic, antiferromagnetic, multiferroic, or ferrimagnetic elements, such as ferrites)A core), or such magnetic element may be a paramagnetic element. However, the component may also be an IC substrate, interposer or another component carrier, for example in the form of a board-in-board. The component may be surface mounted on the component carrier and/or may be embedded in the interior of the component carrier. In addition, other components, particularly those that generate and emit electromagnetic radiation and/or are sensitive to electromagnetic radiation propagating from the environment, may also be used as components.

In an embodiment, the component carrier is a laminate type component carrier. In such embodiments, the component carrier is a composite of multiple layers of structures that are stacked and joined together by the application of pressure and/or heat.

After the treatment of the inner layer structure of the component carrier, one or both opposite main surfaces of the treated layer structure may be symmetrically or asymmetrically covered (in particular by lamination) with one or more further electrically insulating layer structures and/or electrically conductive layer structures. In other words, lamination may be continued until the desired number of layers is obtained.

After the formation of the stack of electrically insulating layer structures and electrically conducting layer structures is completed, the surface treatment of the obtained layer structure or component carrier may be continued.

In particular, in terms of surface treatment, an electrically insulating solder resist may be applied to one or both opposite major surfaces of the layer stack or component carrier. For example, such a solder resist may be formed over the entire major surface and the layer of solder resist may then be patterned to expose one or more electrically conductive surface portions for electrically coupling the component carrier to the electronic periphery. The surface portions of the component carrier that remain covered by the solder resist, in particular the copper-containing surface portions, can be effectively protected from oxidation or corrosion.

In terms of surface treatment, the surface treatment may also be selectively applied to the exposed electrically conductive surface portions of the component carrier. Such a surface treatment may be an electrically conductive covering material on an exposed electrically conductive layer structure (such as, in particular, a pad comprising or consisting of copper, a conductive trace, etc.) on the surface of the component carrier. If such exposed electrically conductive layer structures are not protected, the exposed electrically conductive component carrier material (particularly copper) may oxidize, thereby making the component carrier less reliable. The surface treatment may then be formed as a joint between, for example, a surface mounted component and a component carrier. The surface treatment has the function of protecting the exposed electrically conductive layer structure, in particular the copper circuit, and of effecting the bonding process with one or more components, for example by soldering. Examples of suitable materials for the surface treatment are Organic Solderability Preservative (OSP), electroless Nickel Immersion Gold (ENIG), electroless Nickel Immersion Palladium Immersion Gold (ENIPIG), gold (especially hard gold), electroless tin, nickel-gold, nickel-palladium, and the like.

The aspects defined above and further aspects of the utility model are apparent from the examples of embodiment to be described hereinafter and are explained with reference to these examples of embodiment.

Drawings

Fig. 1 shows a cross-sectional view of a component carrier according to an exemplary embodiment of the utility model.

Fig. 2 shows a cross-sectional view of a component carrier according to another exemplary embodiment of the utility model.

Fig. 3 shows a cross-sectional view of a component carrier according to a further exemplary embodiment of the utility model.

Fig. 4 shows a cross-sectional view of a component carrier according to a further exemplary embodiment of the utility model.

Fig. 5 shows a cross-sectional view of a component carrier according to a further exemplary embodiment of the utility model.

Fig. 6 shows a cross-sectional view of a component carrier according to a further exemplary embodiment of the utility model.

Fig. 7 shows a cross-sectional view of a component carrier according to a further exemplary embodiment of the utility model.

Fig. 8 shows a cross-sectional view of a component carrier according to a further exemplary embodiment of the utility model.

Fig. 9 to 13 show cross-sectional views of structures obtained during execution of a method of manufacturing a component carrier according to an exemplary embodiment of the present utility model, as shown in fig. 13.

Detailed Description

The schematic representations in the drawings are schematic. In the different figures, similar or identical elements are provided with the same reference signs.

Some general considerations upon which exemplary embodiments of the present utility model have been developed will be summarized before the exemplary embodiments are described in further detail with reference to the appended drawings.

In conventional component carriers with air cavities, no protection is provided for the exposed copper areas. For some applications, it is desirable to provide vents in the component carrier to avoid delamination. However, the exposed copper surfaces may tend to oxidize as the oxidizing medium enters the air cavity through the vent holes. This may result in reduced radio frequency performance of the component carrier.

According to an exemplary embodiment of the utility model, a (preferably laminate-like) component carrier (e.g. a printed circuit board, PCB) is provided, wherein an air cavity is preset in the laminate for RF (radio frequency) signal transmission involving electrically conductive layer structures, which cavity may be arranged between the electrically conductive layer structures. Advantageously, one of the electrically conductive layer structures defining the air cavity may be at least partially covered with a protective structure for protecting the electrically conductive layer structure from undesired effects from the environment. Optionally, other electrically conductive layer structures may also be covered with a protective structure. For example, the air cavity may have an air passage leading to the outside of the component carrier through a vent hole or the like. In a wet or corrosive environment, this often results in contamination, functional degradation, or even damage to the exposed electrically conductive layer structure defining the cavity. To overcome this conventional disadvantage, a protective structure may be provided to cover the electrically conductive layer structure defining the air cavity to protect, in particular chemically passivated, the electrically conductive layer structure. This ensures reliable functioning and high radio frequency performance of the component carrier with radio frequency signal transmission function in a simple manner.

Thus, exemplary embodiments of the present utility model may ensure reliable production of an air-cavity supported (air-supported) radio frequency structure of a component carrier. This may be accomplished, according to exemplary embodiments of the present utility model, by placing a dielectric protective structure (such as a thinner dielectric prepreg or core) over the electrically conductive layer structure that facilitates transmission of signals through the cavity. The cavities may also be placed in such a way that copper is not exposed so that the stack material may be used as a protective structure. In an embodiment, a thinner selective dielectric protection treatment (i.e., using an etchant composition with organic particles to enhance surface adhesion) may be applied prior to forming the V-type bonds. A partial surface treatment may also be applied to form the protective structure. In another embodiment, an adhesion promoting layer may be used as a protective layer (e.g., without limitation, a V-bond type adhesion promoter). Exemplary embodiments of the present utility model may have the following advantages: proper radio frequency performance is maintained while protecting the electrically conductive layer structure (e.g., made of copper or other metallic material) defining the air cavity from external influences such as oxidation. Such a protective structure for reliably protecting exposed copper can be formed with less effort. In particular, the air cavity supporting structure of the exemplary embodiments of the present utility model may reduce the amount of expensive radio frequency material used without a significant increase in radio frequency performance.

Exemplary applications of exemplary embodiments of the present utility model are 5G base stations, 6G base stations, millimeter wave radio frequency structures (such as antennas, particularly operating in the frequency range of 20GHz and above), automotive radar applications, wiGig, and cell phones. More generally, exemplary embodiments may facilitate providing a powerful interconnect structure for radio frequency applications. Thus, the exemplary embodiments may be used in any application that utilizes one or more air cavities to improve radio frequency performance. In particular, exemplary embodiments of the present utility model may be used to construct embedded air cavities for low loss transmission.

Exemplary embodiments of the present utility model may provide for reliable production of radio frequency structures supported by air cavities. In this case, copper protection of the radio frequency structure supported by such air cavities may be achieved for long-term environmental exposure of copper.

To avoid undesirable phenomena such as delamination due to thermal expansion of air in the air cavities, exemplary embodiments of the present utility model having one or more air cavities in the PCB may be provided with one or more vents to prevent PCB failure. In conventional methods, the exposed copper may tend to form an oxide layer, thereby degrading radio frequency performance, while the air cavity first increases radio frequency performance. To overcome this and/or other conventional drawbacks, exemplary embodiments of the present utility model provide for covering exposed copper located in an air cavity with a protective structure (e.g., a protective layer) to protect the copper from environments such as temperature variations and humidity.

Signal loss in a component carrier, such as a PCB, may be significantly improved by utilizing one or more air cavities that function as air cavities. The placement of the one or more air cavities has a functional impact, since in an ideal case the one or more air cavities are preferably placed in a position where the concentration of the electromagnetic field provided by the radio frequency structure is strongest. In the case of a Microstrip (MS) patch antenna, this location is directly below the patch antenna in a dielectric medium and between the patch antenna and its reference layer (also denoted as ground layer). Although the aforementioned MS antennas may benefit from the air cavity, the performance of the striplines and MS transmission lines may be greatly improved if the striplines and MS transmission lines are arranged in a so-called floating configuration (floating MS or floating stripline). On the other hand, when reliability is concerned, air cavities in the PCB may become a problem, as entrained air may tend to expand due to temperature variations, resulting in delamination of the layers or cracking of the vias. According to an exemplary embodiment of the present utility model, one or more vents may be provided placed in non-electronically critical areas of the cavity, which would allow free expansion of air. However, copper forming a reference layer (or ground layer) with respect to the radio frequency structure is typically exposed due to the PCB lamination process. In particular, where one or more vents are provided, excess air is provided from the environment to the datum layer, which exposure can become a reliability issue and can limit the useful life of the component carrier. To overcome this and/or other conventional drawbacks, exemplary embodiments of the present utility model may provide coverage for the exposed copper layer (or any other electrically conductive layer structure that serves as a reference layer or ground layer) by a protective structure. For example, such a protective structure may be a protective dielectric layer (e.g., a solder mask). A reference layer may also be formed on a layer below the bottom of the air cavity. In both cases the bottom of the cavity itself will not be copper, but a dielectric material (preferably a radio frequency dielectric material). Advantageously, in the case of a suspended MS structure, for example, unlike the radio frequency performance of a structure with exposed copper, the radio frequency performance of the suspended MS structure does not change significantly due to the presence of the protective structure and advantageously does not change over time.

Accordingly, exemplary embodiments of the present utility model provide a component carrier having an air cavity coupled with air that includes a protected metal structure to form a component carrier of higher radio frequency performance. The exposed metal structure of the component carrier, which may have vents, may be protected while maintaining radio frequency performance. Preferably, the cover covering the air cavity on the upper side may be thick enough to ensure reliable mechanical properties of the component carrier.

Fig. 1 shows a cross-sectional view of a component carrier 100 according to an exemplary embodiment of the utility model.

The component carrier 100 shown may be a plate-like laminate component carrier such as a Printed Circuit Board (PCB). Fig. 1 shows a laminated stack 102, the stack 102 comprising electrically conductive layer structures 106, 108 and one or more electrically insulating layer structures 104. For example, the electrically conductive layer structures 106, 108 may include patterned copper foil. Although not shown in fig. 1, the stack 102 may also include one or more electrically conductive layer structures configured as vertical through-connections, such as copper-filled laser vias. The electrically insulating layer structure 104 may comprise a resin (such as an epoxy resin) optionally including reinforcing particles (e.g., glass fibers or glass spheres) therein. For example, the electrically insulating layer structure 104 may be made of FR 4. In particular, any electrically insulating layer structure 104 may be a core. The multiple ones of the layer structures 104, 106, 108 may be connected by lamination, i.e. by application of pressure and/or heat.

Based on the configuration of the component carrier 100 described below, the component carrier 100 is configured to perform high frequency applications. In particular, the component carrier 100 according to fig. 1 comprises a radio frequency or microwave structure embedded in the stack 102 and is configured to promote or excite microwave or radio frequency propagation. More specifically, the microwave structure shown is embodied as an air cavity 110 for guiding microwaves or other high frequency signals. For example, the component carrier 100 according to fig. 1 may be used for 5G applications. As shown, the cavity 110 is implemented as a hollow volume in the stack 102, the volume being shaped and sized to functionally cooperate with the first and second electrically-conductive layer structures 106, 108 to facilitate transmission of radio frequency signals. Illustratively, the cavity 110 may define a volume in which electromagnetic radiation signals may propagate. Such electromagnetic signals may be transmitted within the component carrier 100 in cooperation with the first electrically-conductive layer structure 106 and the second electrically-conductive layer structure 108. For example, the cavity 110 may be shaped as a cube (e.g., having 3 mm sides) or as a longitudinal channel.

As shown, the second electrically-conductive layer structure 108 is disposed at an outer surface 116 of the stack 102 above the air cavity 110 and above the first electrically-conductive layer structure 106.

As also shown, a portion of the first electrically conductive layer structure 106 in the stack 102 functionally defines the cavity 110 at a lower or bottom end of the cavity 110, and is structurally passivated with respect to the hollow volume of the cavity 110 by a protective structure 112, which protective structure 112 will be described in detail below. The portion of the first electrically-conductive layer structure 106 extends along the entire bottom 122 of the air cavity 110.

According to fig. 1, the first electrically conductive layer structure 106 is configured as a ground layer and the second electrically conductive layer structure 108 is configured as an antenna structure. In order for the electrically conductive layer structures 106, 108 to cooperate with each other via the cavity 110 for emitting high frequency signals, according to fig. 1 the electrically conductive layer structures 106, 108 and the cavity 110 are arranged to overlap in the vertical viewing direction. In addition, the spacing or height h of the antenna structure provided by the second electrically-conductive layer structure 108 relative to the ground or reference layer first electrically-conductive layer structure 106 should be matched to the size of the cavity 110 to effectively transmit high frequency signals between the second electrically-conductive layer structure 108 and the first electrically-conductive layer structure 106. The ground plane and the antenna structure cooperate with the cavity 110 between the ground plane and the antenna structure to complete the transmission of high frequency signals. For example, the signal may be coupled into the component carrier 100 or out of the component carrier 100 through a second electrically conductive layer structure 108 configured as an antenna structure. The first electrically conductive layer structure 106, which is configured as a ground layer, may provide a suitable potential. The cavity 110 may facilitate lower loss signal transmission.

As shown, a vent hole 118 is formed in an upper portion of the stack 102 for enabling gas communication between the exterior of the component carrier 100 and the air cavity 110. Illustratively, the vent 118 may facilitate pressure equalization between the air cavity 110 and the surroundings of the component carrier 100. As shown, the vent holes 118 extend between the air cavity 110 and the exterior of the stack 102. By exchanging air between the interior of the cavity 110 and the exterior of the component carrier 100 through the vent holes 118, and by exchanging pressure through the vent holes 118, pressure differences and corresponding stresses in the component carrier 100, such as stresses caused by temperature changes, may be suppressed. Advantageously, this also suppresses the layering tendency of the layer structures 104, 106, 108 of the stack 102. However, the pressure balance achieved between the interior and exterior of the component carrier 100 via the vent holes 118 also exposes the first electrically-conductive layer structure 106 in the interior of the cavity 110 to corrosive or oxidizing media, such as moisture in ambient air, flowing from the exterior of the component carrier 100 into the hollow cavity corresponding to the cavity 110. Such corrosion, oxidation, or other types of contamination of the first electrically-conductive layer structure 106 may result in significant degradation of high-frequency performance and quality of the transmitted signal.

To overcome the above-described problems, the described embodiments of the present utility model provide a protective structure 112, the protective structure 112 covering the exposed portion of the first electrically conductive layer structure 106 at the boundary 114 of the air cavity 110. Illustratively, the protective structure 112 separates the first electrically-conductive layer structure 106 from the corrosive or oxidizing medium in the cavity of the air cavity 110 or passivates the first electrically-conductive layer structure 106. In other words, any type of crossing or transition (e.g., diffusion, migration, etc.) of the corrosive or oxidizing medium from the hollow volume of the cavity 110 through the protective structure 112 to the first electrically conductive layer structure 106 may be inhibited or impossible. Thus, the protective structure 112 may be configured to protect the first electrically conductive layer structure 106 from undesired interactions with the medium in the hollow volume of the cavity 110, in particular, corrosion and oxidation may be prevented. Illustratively, the protective structure 112 prevents oxidation or corrosion of the copper material of the first electrically conductive layer structure 106 by moisture inside the cavity 110.

Preferably, the protective structure 112 comprises or consists of a dielectric material. By taking this measure, it may be ensured that the protective structure 112 propagates signals along the substantially unaffected electrically conductive layer structures 106, 108 and the cavity 110 and/or propagates signals through the substantially unaffected electrically conductive layer structures 106, 108 and the cavity 110.

In the embodiment of fig. 1, the protective structure 112 is configured as a coating that covers the bottom 122 and the sidewalls 124 of the air cavity 110. Such a coating may be formed by spraying or deposition, for example.

Fig. 1 illustrates an advantageous placement of the air cavities forming the cavity 110. The air cavity is surrounded by a dielectric material which may advantageously have the same Dk distribution of the electromagnetic field influencing material if the height h of the antenna remains unchanged in all configurations.

Fig. 2 shows a cross-sectional view of a component carrier 100 according to another exemplary embodiment of the utility model.

The embodiment of fig. 2 differs from the embodiment of fig. 1 in particular in that, according to fig. 2, the protective structure 112 is realized as a planar layer and is made of another material than the material according to fig. 1. More specifically, the protective structure 112 according to fig. 2 is a planar layer covering only the bottom of the air cavity 110. In the illustrated embodiment, the protective structure 112 may be, for example, a surface treatment such as OSP, ENIG, or enigig. Thus, the protective structure 112 may also be metallic, but should be matched or modified in conjunction with the geometry of the air cavity 110 to conform to the signal transmission requirements of the electrically conductive layer structures 106, 108.

Fig. 3 shows a cross-sectional view of a component carrier 100 according to a further exemplary embodiment of the utility model.

The embodiment of fig. 3 differs from the embodiment of fig. 2 in particular in that, according to fig. 3, the protective structure 112 is formed from the material of the laminated layer stack 102, i.e. the protective structure 112 may be formed integrally with the laminated layer stack 102. More specifically, the protective structure 112 according to fig. 3 forms part of one of the electrically insulating layer structures 104 of the stack 102. In the presently described embodiment, the protective structure 112 may include, for example, an epoxy and a reinforcing fiberglass. For example, the protective structure 112 of fig. 3 may be made of prepreg or FR 4. In the embodiment of fig. 3, the protective structure 112 should be formed to a thickness sufficient to prevent gas flow from the hollow cavity of the cavity 110 to the first electrically conductive layer structure 106 below the protective structure 112.

Fig. 4 shows a cross-sectional view of a component carrier 100 according to a further exemplary embodiment of the utility model.

The embodiment of fig. 4 differs from the embodiment of fig. 2 in particular in that, according to fig. 4, the protective structure 112 is a planar layer extending over the entire width of the component carrier 100 and can be made of another material than the material according to fig. 2. Furthermore, the first electrically conductive layer structure 106 is patterned according to fig. 4, but the first electrically conductive layer structure 106 may be a continuous metal layer according to any of fig. 1-3.

According to fig. 4, the protective structure 112 is implemented as an adhesion promoter that promotes adhesion of the first electrically conductive layer structure 106 to the stack 102. Such adhesion promoters, including for example silanes, can thus fulfill a dual function. First, the adhesion promoting formulation protective structure 112 may enhance interlayer adhesion within the stack 102. Second, the adhesion promoting type protective structure 112 may protect or passivate the first electrically conductive layer structure 106 formed with the protective structure 112 from any other adverse effects of oxidizing, corrosive, or aggressive atmospheres in the cavity forming the cavity 110. Optionally, the adhesion promoter may be provided with one or more additives to enhance the protective function of the protective structure 112 against oxidation or corrosive gases and/or liquids, and/or other contaminants.

Fig. 5 shows a cross-sectional view of a component carrier 100 according to a further exemplary embodiment of the utility model.

The embodiment of fig. 5 differs from the embodiment of fig. 3 in particular in that, according to fig. 5, the first electrically conductive layer structure 106 is patterned, and the electronic component 120 is embedded in the stack 102 and electrically coupled with the first electrically conductive layer structure 106. More specifically, the component carrier 100 according to fig. 5 comprises a high frequency component 120 embedded in the stack 102. For example, the high frequency component 120 may be a radio frequency semiconductor chip that facilitates signal generation, transmission, and/or processing in the component carrier 100.

Fig. 6 shows a cross-sectional view of a component carrier 100 according to a further exemplary embodiment of the utility model.

In the embodiment of fig. 6, a plurality of further electrically conductive layer structures 130, for example made of copper, are shown. Furthermore, it is shown that some of the electrically insulating layer structures 104 are realized by a stable core material, as indicated by reference numeral 132. As shown, the layers are stacked one above the other in the Z-direction or in the thickness direction of the stack. Other ones of the electrically insulating layer structures 104 may be made of prepregs, preferably low flow prepregs as indicated by reference numeral 134. Preferably, at least two upper electrically insulating layer structures, indicated by reference numeral 134 in fig. 6, should be made of low flow prepregs. An electrically insulating layer structure, indicated by reference numeral 134, may facilitate interlayer adhesion of the stack 102 formed by lamination. When such an electrically insulating layer structure is constructed with a low-flow prepreg, it can be ensured that no or substantially no resin flows into the air cavity 110 during lamination, which improves the radio frequency performance of the component carrier 100.

In the embodiment shown in fig. 6, the protective structure 112 is implemented as a layer of a dielectric solder mask. Such solder mask or solder resist may be a relatively thin layer of lacquer-like polymer that may also be applied to the external copper traces of a Printed Circuit Board (PCB) to prevent oxidation and to prevent solder bridges between closely spaced pads. When constructing the protective structure 112 with a solder mask material, no additional process is required to be introduced in the PCB manufacturing process to form the protective structure.

Fig. 7 shows a cross-sectional view of a component carrier 100 according to a further exemplary embodiment of the utility model.

The embodiment of fig. 7 differs from the embodiment of fig. 6 in particular in that, according to fig. 7, the protective structure 112 is formed as part of the laminated layer stack 102 (instead of as a solder mask), for example, the protective structure 112 is formed as a core layer.

Fig. 8 shows a cross-sectional view of a component carrier 100 according to a further exemplary embodiment of the utility model.

The embodiment of fig. 8 differs from the embodiment of fig. 6 in particular in that, according to fig. 8, the protective structure 112 is formed as part of the laminated layer stack 102, for example, the protective structure 112 is formed as a layer of a low-flow prepreg.

Fig. 9 to 13 show cross-sectional views of structures obtained when the method of manufacturing the component carrier 100 according to the exemplary embodiment of the present utility model is performed, as shown in fig. 13.

Referring to fig. 9, as described above, a layer stack 102 is shown. However, a release layer 138 of a less viscous material is embedded in the stack 102 directly above the first electrically conductive layer structure 106. The release layer 138 may be used to form cavities in the layer stack 102 to form the air cavities 110. For example, such release layer 138 may be made of a material that exhibits poor adhesion relative to the surrounding overlying material. For example, a suitable material for the release layer 138 is polytetrafluoroethylene (PTFE, teflon), or a waxy compound.

An alternative manufacturing process not using the release layer 138 is to use a pre-cut core and prepreg.

Furthermore, the bonding film may be applied directly to the copper traces.

Referring to fig. 10, an opening or cavity may be formed in the layer stack 102 by removing a piece of the layer stack 102 bounded on the bottom side by the release layer 138. The method of manufacture may include forming circumferential cutting grooves in the layer stack 102 that extend to the release layer 138, thereby separating the block from the remainder of the layer stack 102. Cutting the trench may be accomplished by, for example, laser drilling or mechanical drilling. Fig. 10 shows a structure in which the piece of material has been removed from the layer stack 102. In addition, the release layer 138 has also been removed, for example, the release layer 138 is removed by etching. Thus, a cavity is obtained, which cavity then forms the air cavity 110.

Other methods for forming the cavity, such as milling, may also be implemented.

Referring to fig. 11, a layer-type protection structure 112 may be formed at the bottom of the cavity where the cavity 110 is formed later. This may be done, for example, by dispensing, printing, spraying, depositing, etc.

Referring to fig. 12, the cavity is closed at its top side by a cover 140, thereby completing the formation of the air cavity 110. For example, a plate-like cover 140 may be attached to the upper major surface of the structure shown in fig. 11 by using a curable layer 142, such as a sheet of resin or prepreg. Preferably, a low flow resin or a low flow prepreg is used to avoid resin flow into the air cavity 110.

To obtain a component carrier 100 according to fig. 13, an electrically conductive layer (e.g. a copper foil or a deposited copper layer) may be formed on the top surface of the stack 102 and may be patterned to form a second electrically conductive layer structure 108 as an antenna structure (e.g. wound or spiral). In addition, vent holes 118 may be formed in cover 140, such as by drilling, to form a passageway to air cavity 110.

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. In addition, elements described in association with different embodiments may be combined.

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

The practice of the utility model is not limited to the preferred embodiments shown in the drawings and described above. On the contrary, many variations are possible, even in the case of radically different embodiments, which use the solutions and principles according to the present utility model shown.

Claims

1. A component carrier (100), characterized in that the component carrier (100) comprises:

a stack (102), the stack (102) comprising at least one electrically insulating layer structure (104), a first electrically conductive layer structure (106) and a second electrically conductive layer structure (108);

-an air cavity (110) located in the stack (102), the air cavity (110) being configured to facilitate transmission of radio frequency signals together with the first electrically conductive layer structure (106) and the second electrically conductive layer structure (108); and

-a protective structure (112), the protective structure (112) covering at least a portion of the first electrically conductive layer structure (106) located at a boundary (114) of the air cavity (110).

2. The component carrier (100) according to claim 1, wherein the air cavity (110) is cubical.

3. The component carrier (100) according to claim 1, wherein the air cavity (110) is a longitudinal channel.

4. The component carrier (100) according to claim 1, wherein the portion of the first electrically conductive layer structure (106) extends along a bottom (122) of the air cavity (110).

5. The component carrier (100) of claim 1, wherein the protective structure (112) is configured to protect the first electrically conductive layer structure (106) from at least one of corrosion, oxidation, and migration.

6. The component carrier (100) according to claim 1, wherein the first electrically conductive layer structure (106) is configured as a reference layer.

7. The component carrier (100) of claim 6, wherein the reference layer is a ground layer.

8. The component carrier (100) according to claim 1, wherein the second electrically conductive layer structure (108) is configured as at least part of an antenna structure.

9. The component carrier (100) according to claim 1, wherein the second electrically conductive layer structure (108) is provided at an outer surface (116) of the stack (102) above the air cavity (110).

10. The component carrier (100) according to claim 1, wherein the component carrier (100) comprises a vent hole (118) extending between the air cavity (110) and an exterior of the stack (102).

11. The component carrier (100) according to claim 1, characterized in that the component carrier (100) comprises at least one high frequency component (120), the high frequency component (120) being surface mounted on the stack (102) and/or embedded in the stack (102).

12. The component carrier (100) according to claim 1, wherein the protective structure (112) is a coating at the bottom (122) of the air cavity (110).

13. The component carrier (100) according to claim 1, wherein the protective structure (112) is configured as a coating covering at least a portion of at least a side wall (124) of the air cavity (110).

14. The component carrier (100) according to claim 12 or 13, wherein the protective structure (112) is a layer of dielectric material or a layer of metallic material.

15. The component carrier (100) according to claim 12 or 13, wherein the protective structure (112) is a resin layer.

16. The component carrier (100) according to claim 12 or 13, wherein the protective structure (112) is an epoxy layer.

17. The component carrier (100) according to claim 12 or 13, wherein the protective structure (112) is a polytetrafluoroethylene layer.

18. The component carrier (100) according to claim 12 or 13, wherein the protective structure (112) is an adhesion promoter layer that promotes adhesion of the first electrically conductive layer structure (106) to the stack (102).

19. The component carrier (100) according to claim 12 or 13, wherein the protective structure (112) is a solder resist layer.

20. The component carrier (100) according to claim 1, wherein the protective structure (112) forms part of the at least one electrically insulating layer structure (104).

21. The component carrier (100) according to claim 1, wherein the protective structure (112) comprises a surface treatment.