The invention concerns a component carrier, according to the preamble of claim 1, and a package, according to the preamble of claim 9.
The invention relates to component carriers comprising a stack comprising a plurality of electrically conductive layer structures and at least one electrically insulating layer structure, a component provided in and/or on the stack, said component comprising at least one electrically conductive surface, e.g. in form of pads to establish an electrical connection, connected to an electrically conductive connecting element, said connecting element extending from said electrically conductive surface away from the stack and configured to be connected to an external component to be mounted on the component carrier when at least one connecting surface provided in/on the external component is faced to the electrically conductive surface of the component.
A package as the basis for the present invention can comprise a stack comprising a plurality of electrically conductive layer structures and at least one electrically insulating layer structure, a component provided in and/or on the stack, said component comprising at least one electrically conductive surface, and at least one external component, said external component comprising at least one connecting surface. Said component and said at least one external component are electrically connected one to each other, in particular with the at least one electrically conductive surface of the component and the at least one connecting surface of the external component facing each other, by at least one connecting element.
The connection between the carrier or package and an external component can be achieved for instance as proposed in CN 114334682 A by nanowires provided on two opposed lands of two packages structures (i.e. flip chip on a substrate) and a conductive intermediate material.
The CN 114582744 A, too, discloses connection features of chip packaging through nanowires provided on pillars placed one opposite to each other.
On other kinds of carriers or packages, at least one external component can be mounted or provided on/in the carrier and connected with a further component in electrically conducting manner directly or indirectly. The measures for ensuring a safe connection during manufacture and in use under changing ambient conditions, in particular under changing temperature conditions with different expansion of the different connected components are very complicate and expensive. In spite of all this effort, the known arrangements provided on a component carrier, directly or indirectly connected to a further component, causes quality and reliability troubles relating to the alignment in all orthogonal directions between the components and the component carrier and between the component connections. In particular, the CTE (coefficient of thermal expansion) mismatch among the components and with respect to the carrier at the location where one component is mounted leads to mechanical stress on the connection between the carrier and the component and between the components as well; in the exemplary embodiment in which the component provided in and/or on the stack is a bridge connected to at least two external components, the CTE (coefficient of thermal expansion) mismatch between the bridge and the carrier at the location where one or two of the external components are assembled causes an heterogeneous expansion/displacement of the connecting areas (i.e. the electrically conductive surfaces of the bridge, the connecting surfaces of the external components and the other areas on the carrier where the external components are connected), negatively impacting on the stresses of the connections between the external components and the bridge as well as between said external components and the carrier, improving the risk of breakage and/or failure of these connections during the assembly and/or in the assembled condition along the time.
It is the object of the present invention to overcome the disadvantages of the prior art and to provide an improved component carrier and an improved package, that can in particular achieve a reliable and stable connection between the components and the component carrier irrespective of the environmental conditions and by a simple and cheap, though reliable, arrangement. Especially, the direct connection between components should be ameliorated, where at least one of the component is exposed to mechanical stress caused by the carrier having different physical properties (like CTE) where this component is mounted or integrated, in particular even for difficult arrangements, when the component is a bridge connecting two components or a component with one component and a carrier structure.
The scope of the present invention is as defined by the subject-matter of the independent claims. The dependent claims specify particular embodiments of the present invention.
To provide an enhanced component carrier the present invention proposes that the connecting element is made of a heterogeneous conductive structure that is arranged to permanently compensate for a relative movement of said electrically conductive surface of the component and said connecting surface of the external component with the component carrier. The term “permanently compensate for a relative movement between the two surfaces” means that during the assembly or in the assembled condition of said components, a mismatching of the alignment between the two surfaces, and/or different expansions rate during temperatures changing of the materials of the components and/or of the carrier structures carrying at least one of said components is compensated by the structural and/or intrinsic characteristics of said heterogeneous conductive structure, along the planar direction of the component carrier (along the x-y-direction) and/or along the component carrier thickness direction (along the z-direction). With an arrangement according to the invention it is possible to balance mechanical stress on the one hand side and compensate geometrical process-related differences (e.g. production-related inaccuracies) in the x-, y- and z-axes. Whereas the mechanical stresses can be caused by the CTE mismatching between the component, the external component and the stack where the component is provided (see above), the geometrical inaccuracy can happen for several reasons; for example, the component provided in and/or on the stack can be inclined (for example the planar extension of the component and/or the bottom/upper surface of the component is not parallel with respect to the planar main extension/one external surface of the stack) due to the fact that the electrically conductive layer structures distribution vertically below the component (along the component carrier thickness) is not constant, causing the inclination-tilting of the component, resulting in a misalignment of the components along the vertical direction (z-direction) of the component carrier. In particular, due a denser distribution of an electrically conductive layer structure (i.e. conductive traces, pads, etc.) in an area partially vertically overlapping the component, the abutting and adjacent electrically insulating layer structure material (i.e. dielectric material) accumulates in a different manner with respect to areas having a coarser distribution of the (respective) electrically conductive layer structure, resulting in surface supporting the component in a different manner in different areas, resulting in a tilted assembled component. From experimental tests, this effect is widely demonstrated when the electrically insulating layer structure comprises resin material, preferably with fillers distributed therein, more preferably comprising inorganic fillers/non fibrous fillers, in particular spherical fillers, and/or when the amount of the electrically conductive layer structure(s) (i.e. in terms of volume/weight per unit) below a portion vertically overlapping the component is higher than the respective amount of electrically conductive layer structures vertically overlapping a further portion of the same component; preferably, the resulting tilting of the component is between 0.05° and 10°. Due to the inclination of the component and/or the wrong assembly of the external component with the component, the external component (i.e. the lower surface and/or the planar main extension thereof) during and in the assembled condition can be preferably inclined with respect to the component where it is assembled; according to one embodiment, the component and the external component can result with a vertical distance difference from 0.1 to 10 μm between two opposed planar extremities. Additionally or alternatively, the misalignment between the component and the external component is preferably along the planar direction (x-y plane of the component carrier); said misalignment can occur due to the wrong placement of one component with respect to the other and/or due to the tolerances between the electrically conductive surfaces of the component and those of the connecting surfaces of the external component; this misalignment can occur during the assembly between the component and the further component or in the assembled (working) condition for example due to the temperature variations; this planar misalignment can be of a value between 0.1 to 10 μm along the planar (x-y) direction. The heterogeneous conductive structure according to the present invention is configured to compensate these kinds of the geometrical inaccuracy, especially within the above mentioned ranges.
An external component is to be understood as a second component that can be arranged on the component carrier but is separate from the layer structures of the component carrier before assembly. In the in-use (assembled) position of the component carrier the second (external) component is arranged to be connected preferably permanently electrically and/or mechanically to a first component arranged on the component carrier, which first component can be integrated in the layer structures of the component carrier.
Preferred, the connecting element is elastically or at least temporarily deformable, where the deformation is at least one of a compression, elongation, shearing or bending. In this way, a safe connection during assembly and during operation under changing ambient conditions, in particular under changing temperature conditions, also in the operational position can be guaranteed.
One first embodiment of the present invention is characterized in that the heterogeneous structure of the connecting element comprises a solid electrically conductive material with voids inside. This may bring the advantage of ensuring a reliable physical and electrical connection while reducing the mass of the component carrier, with the deformability provided by the heterogeneous structure of the connecting element itself.
Said voids can be advantageously contain a gas, in particular air, or can be at least partly evacuated, said voids being preferably at least partially connected one to each other defining air passages. This may bring the advantage of adjusting a physical property, for example the malleable/pliable ability of the heterogeneous structure.
Another embodiment according to the invention provides that the voids comprise a filler, said voids being preferably at least partially sealed one against each other. The filler can comprise or consist of a resin and/or an elastomeric material and/or a liquid. This may bring the advantage of having a diverse kind of materials to adjust the heterogeneous structures' property/behaviour. The filler could also be electrical conductive. The sealing between the voids has the advantage of leading to a different/more controllable deformability/elasticity of the connecting element due to fact that the filler, with specific deformability/elasticity properties, does not have the possibility to expand into other spaces other than that defined by the respective void. A conductive filler would be then fully justified, properly conjugating the deformability and the conductivity properties.
Another embodiment of the invention is characterized in that part of the voids are open to the outside of the solid material and thereby affect the external roughness and/or the size of the surface area of the connecting element. This may bring the advantage of ensuring a reliable connection to the heterogeneous structure (by other material, what could be the underfill to protect the heterogeneous structure from harsh environment), for example defining the deformability of the external portion of the connecting element through its rough/jagged external surface defined by the exposed voids.
A further embodiment of the invention can be characterized in that the heterogeneous structure comprises a plurality of electrically conductive nanowires spaced apart one to each other, connected to the electrically conductive surface and extending away from the stack. This may bring the advantage of enhancing the flexibility of the heterogeneous structure. Additionally, a redundant connection can be achieved, due to the fact that a plurality of nanowires leads to a reliable electrical connection even in case of breakage of few of those nanowires.
Preferred, each of said plurality of nanowires is connected to and/or bonded to and/or monolithically merged from the electrically conductive surface. This may bring the advantage of providing a reliable connection, while still having flexible (physical) properties.
A still further embodiment of the invention in characterized in that the heterogeneous structure comprises an electrically conductive porous material connected to the electrically conductive surface. This may bring the advantage of enlarging the surface area of the heterogeneous structure and thus ensuring a reliable connection to the electrically conductive surface, said porosity defining the deformability of the of the connecting element assuring at the same time the proper conductivity features provided from the remaining conductive material.
According to a further embodiment of the invention, the heterogeneous structure can comprise a liquid metal structure connected to the electrically conductive surface. This may bring the advantage of high flexibility since liquids are known to be easy deformable substances.
Another embodiment of the present invention shows a heterogeneous structure which comprises a solder bump with rubber particles inside. This combination of (visco)elastic rubber with solder material may provide good physical and electrical connection while having flexible properties.
The component may be at least partially exposed outside the stack, providing an easy to manufacture way to establish a reliable connection. Preferred is an arrangement, wherein the stack comprises at least one exposed electrically conductive surface on the main surface where the component is exposed, said at least one exposed electrically conductive surface being connected to an external conductive structure extending from the at least one exposed electrically conductive surface and configured to expose a surface at a higher vertical level than that of the at least one exposed electrically conductive surface. This may bring the advantage of simplifying the connection process, while ensuring a reliable connection during operation, especially due to the fact that the external conductive structure can compensate the different heights, i.e. along the z direction, exemplarily caused by the presence of the connecting element, leading to an easier assembly of the external component or other components on a more planar/constant surface/level.
Most preferred, according to a further embodiment, a damping structure is provided between the component and the stack. This allows a simpler and easier to manufacture arrangement compared to the know solution with a micro socket array having a complicate and expensive shape. Additionally, the damping structure imparts an additional possible eventual displacement of the component with respect to the component carrier, improving the mismatching compensation in terms of CTE and tolerances.
According to a further embodiment of the invention, the component is at least partially embedded in the stack, in particular exposing only at least a portion of the connecting element. This may bring the advantage of providing mechanical protection to at least two (side) walls, while offering exposed connection elements to be connected.
According to a still further embodiment of the invention the component is configured to be connected to at least two external components, in particular with the component providing a bridge function. This can increase the flexibility of the design of the component carrier. In particular, the bridge function may provide a short local distance, which enables fast signal transmission between the respective at least two components, e.g. between a HBM (high bandwidth memory) and a processing component (CPU, GPU, etc.) or to establish a fast communication between chiplets. All quality and reliability troubles relating to the alignment in all orthogonal directions between the component with the bridge functionality and the external components and/or CTE (coefficient of thermal expansion) mismatch between the bridge and the connected components, in particular mechanical stress on the connections (see above), can be omitted and a reliable and stable connection between the external components and the component with the bridge function can be achieved irrespective of the environmental conditions and by a simple and cheap, though reliable, arrangement; additionally and/or alternatively, in case the stack exhibits a non-planar external surface (for example due to the fact that said external surface comprises an electrically insulating layer structure with resin material, preferably with fillers distributed therein, more preferably inorganic fillers/non fibrous fillers in particular spherical fillers), the external component can be assembled on the bridge on one side, and on the non-planar surface of the stack on the other side, assuming a position inclined with respect to the component carrier planar extension; the inclination can be unpredictable and/or can be improved due to an eventual inclination of the bridge itself (see above). Any mismatching of the alignment between the contacting surfaces on the bridge and the external components, respectively, and/or different expansions rate during temperatures changing of the materials is compensated by the structural and/or intrinsic characteristics of said heterogeneous conductive structures connecting the bridge component with the external components, along the planar direction of the component carrier (along the x-y-direction) and/or along the component carrier thickness direction (along the z-direction).
The present invention as explained in the preceding paragraphs can overcome the disadvantages of the prior art by a connection where the damping effect is obtained by the dimensions (nanowires) and/or the materials (other alternatives) of the contacting protruding elements.
The objects of the present application can also be achieved by a package, which is characterized in that the connecting element is made of a heterogeneous conductive structure that is arranged to permanently compensate for a relative movement of said electrically conductive surface of the component and said connecting surface of the external component with the component carrier. The term “permanently compensate for a relative movement between the two surfaces” means that during the assembly or in the assembled condition of said components, a mismatching of the alignment between the two surfaces, and/or different expansions rate during temperatures changing of the materials of the components and/or of the carrier structures carrying at least one of said components is compensated by the structural and/or intrinsic characteristics of said heterogeneous conductive structure, along the planar direction of the component carrier (along the x-y-direction) and/or along the component carrier thickness direction (along the z-direction).
Preferred, the connecting element is elastically or at least temporarily deformable, where the deformation is at least one of a compression, elongation, shearing or bending. In this way, a safe connection during manufacture and in use under changing ambient conditions, in particular under changing temperature conditions, can be guaranteed.
According to a first embodiment of the package according to the invention, the heterogeneous structure of the connecting element comprises a solid electrically conductive material with voids inside. This may bring the advantage of ensuring a reliable physical and electrical connection while reducing the mass of the component carrier and therefore also of the package as a whole, with the deformability provided by the heterogeneous structure of the connecting element itself.
Advantageously, the voids of the component carrier within the package can contain gas, in particular air, or are at least partly evacuated, in particular said voids being preferably at least partially connected one to each other defining air passages. This may bring the advantage of adjusting a physical property, for example the malleable/pliable ability of the heterogeneous structure.
Another embodiment is characterized in that the voids of the component carrier within the package comprise a filler, in particular said voids being preferably at least partially scaled one to against each other. The filler can comprise or consist of a resin and/or an elastomeric material and/or a liquid. This may bring the advantage of having a diverse tool of materials to adjust the heterogeneous structures' property/behaviour.
Another embodiment of the invention is characterized in that part of the voids of the component carrier within the package are open to the outside of the solid material and thereby affect the external roughness and/or the size of the surface area of the connecting element. This may bring the advantage of ensuring a reliable connection to the heterogeneous structure (by other material), for example defining the deformability of the external portion of the connecting element through its rough/jagged external surface defined by the exposed voids.
A still further embodiment of the invention is characterized in that the heterogeneous structure of the package comprises a plurality of electrically conductive nanowires distanced spaced apart one to each other, connected to the electrically conductive surface and extended extending away from the stack. This may bring the advantage of enhancing the flexibility of the heterogeneous structure. Additionally, a redundant connection can be achieved, due to the fact that a plurality of nanowires leads to a reliable electrical connection even in case of breakage of few of those nanowires.
In this embodiment it is of advantage, if each of said plurality of nanowires in the package are each is connected to and/or bonded to and/or monolithically merged from the electrically conductive surface. This may bring the advantage of providing a reliable connection, while still having flexible (physical) properties.
A still further embodiment of the invention is characterized in that the heterogeneous structure of the package comprises an electrically conductive porous material connected to the electrically conductive surface. This may bring the advantage of enlarging the surface area of the heterogeneous structure and thus ensuring a reliable connection to the electrically conductive surface, said porosity defining the deformability of the of the connecting element assuring at the same time the proper conductivity features provided from the remaining conductive material.
A still further embodiment of the invention provides a heterogeneous structure within the package that comprises a liquid metal structure connected to the electrically conductive surface. This may bring the advantage of high flexibility since liquids are known to be easy deformable substances.
Another embodiment of the invention is characterized in that the heterogeneous structure of the package comprises a solder bump with rubber particles inside. This combination of (visco) elastic rubber with solder material may provide good physical and electrical connection while having flexible properties.
According to the present invention, a further embodiment of a package is characterized in that the connecting element comprises two elements, a first element connected to the at least one electrically conductive surface and a second element connected to the at least one connecting surface, said two elements being connected one to each other providing the electrical connection between the at least one electrically conductive surface of the component with the at least one connecting surface of the external component. This may bring the advantage of creating a connection between two respective components, which is able to compensate relative movement between the components during or after the manufacturing process. Moreover, the compensation is distributed to two elements, relaxing the eventual (mechanical) stresses deriving from the use of one element only.
Preferred, the two elements in this package are connected one to each other through their mutual frontal contact, preferably, said frontal contact is provided by the extremity of each element opposed to the extremity in contact/associated with the at least one electrically conductive surface of the component or the at least one connecting surface of the external component. For frontal contact it is meant as provided along the stack thickness and/or the mounting direction of the component and the external component; the frontal contact may result in a deformation of the two elements at the portion of the contact (such us the deformation of the nanowires or the porous portion comprised in the conductive elements) due to the decrease of the distance between the component and the external component during/after their connection; according to a preferred embodiment of the present invention, the frontal contact may result in the partial insertion of one of the two elements inside the opposed element and vice versa (for example, nano wires comprised in one element are inserted in the spaces between the nano wires comprised in the opposed element).
According to an embodiment, the mutual frontal connection would involve only a partial (frontal) portion/surface of the involved element (i.e. only a portion of the nanowires comprised in one of the two elements interacts with the opposed connecting element or only a portion of the porous material interacts of the opposed element). This may bring the advantage of ensuring a highly reliable connection during and after the manufacturing process even in case of not completely aligned elements and/or different heights of associated couples of said elements (due for example by the vertical misalignment of the component and/or the external component), respectively.
Another embodiment according to the invention is characterized in that the two elements in this package are connected one to each other by the at least partial intertangle of the nanowires of the first element with the nanowires of the second element. This may bring the advantage of ensuring permanent connection between the respective components.
A still further embodiment is characterized in that within the package the connecting element and/or the first element and/or the second element is deformed at the contact portion with the respective at least one electrically conductive surface or at least one connecting surface or the opposing first or second element. This may bring the advantage of ensuring physical and/or electrical connection without breakage due to deformation, maintaining at the same time a stiff and compact structure of the remaining connecting element.
Preferred, the at least one electrically conductive surface of the component and the at least one connecting surface of the external component within the package are solely connected one to each other by the connecting element. This may keep the lateral distance between the components short and ensures fast data or current connection.
Further preferred, the connecting element and/or the first element and/or the second element within the package are at least partially covered by a protecting material. This may enhance the long-life performance since the components are shielded from environment.
A further embodiment of the invention is characterized in that an underfill structure is provided within the package between the component and the external component. This may bring the advantage of protecting the connection from the environment, for example, oxidation by air.
Another embodiment according to the invention is characterized in that the stack within the package comprises at least one exposed electrically conductive surface on the main surface where the component is exposed, said at least one exposed electrical conductive surface being connected to an external conductive structure extending from the at least one exposed electrical conductive surface and configured to expose a surface at an higher vertical level than that of the at least one exposed electrical conductive surface. This may bring the advantage of ensuring a reliable physical or electrical connection even at different levels in stack thickness direction.
Preferred, a damping structure is provided between the component and the stack in the package. This may further compensate for a relative movement between the component and the stack and may strengthen the integrity of the package.
Further, an arrangement of the package is of advantage, wherein the component is at least partially embedded in the stack, in particular exposing only at least a portion of the connecting element. This may bring the advantage of providing mechanical protection to at least two (side) walls, while offering exposed connection elements to be connected.
The component within the package is preferred configured to be connected to at least two external components, and most preferred it can have a bridge function. This can increase the flexibility of the design of the component carrier. In particular, the bridge function may provide a short local distance, which enables fast signal transmission between the respective at least two components. All quality and reliability troubles relating to the alignment in all orthogonal directions between the component with the bridge functionality and the external components and/or CTE (coefficient of thermal expansion) mismatch between the bridge and the connected components, in particular mechanical stress on the connections, can be omitted and a reliable and stable connection between the external components and the component with the bridge function can be achieved irrespective of the environmental conditions and by a simple and cheap, though reliable, arrangement. Also the CTE mismatch by the surrounding component carrier and the components causes a lot of mechanical stress. Due to the placement of component directly on or in the component carrier, this component is exposed to another mechanical stress level than the external components, what is compensated according the invention by the conductive connection element. Any mismatching of the alignment between the contacting surfaces on the bridge and the external components, respectively, and/or different expansions rate during temperatures changing of the materials is compensated by the structural and/or intrinsic characteristics of said heterogeneous conductive structures connecting the bridge component with the external components, along the planar direction of the component carrier (along the x-y-direction) and/or along the component carrier thickness direction (along the z-direction).
The component carrier can further be 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 metal, for example 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).
The at least one electrically insulating layer structure can comprise 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 (Teflon), 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, liquid crystal polymer and/or cyanate ester resins may be implemented in the component carrier as electrically insulating layer structure.
The at least one electrically conductive layer structure may comprise 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 coated with supra-conductive material such as graphene. The conductive layer may form electrical or electronical components, conductive traces, vias or the like.
The at least one component can be selected from a group consisting of e.g. 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, a logic chip, and an energy harvesting unit. However, other components may be embedded in the component carrier. For example, a magnetic element can be used as a component. Such a magnetic element may be a soft magnetic element, in particular a ferromagnetic element, an antiferromagnetic element or a ferrimagnetic element, for instance a ferrite core 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, in particular those which generate and emit electromagnetic radiation and/or are sensitive with regard to electromagnetic radiation propagating from an environment, may be used as component.
In an embodiment, the component carrier is a laminate-type component carrier. In such an embodiment, the component carrier is a compound of multiple layer structures which are stacked, in particular parallel stacked, and connected together by applying a pressing force, if desired accompanied by heat. The component carrier may be configured to carry further electric and/or electronic components, such as resistances, capacitors, diodes, transistors, or integrated circuits.
In the context of the present application, the term “liquid metal structure” may particularly denote any arrangement or composition being metal-based and being liquid or paste-like at or near the temperature of use of the component, arrangement or apparatus in which the liquid metal structure is utilized. For instance, mercury is a stable liquid elemental metal at room temperature, while Caesium, Gallium and Rubidium have melting points slightly above room temperature. Other than that, eutectic alloys could be utilized, with an alloy melting point lower than the melting points of any of the constituent metals. Such alloys can be mercury-based or gallium-based. If need may be, deformable shells around liquid or paste-like metal structures could be provided.
In the context of the present application, the term “main surface” of a body may particularly denote one of two largest opposing surfaces of the body or outermost opposing surfaces of the body. The main surfaces may be connected by circumferential side walls. The thickness of a body may be defined by the distance between the two opposing main surfaces.
In the context of the present application, the term “heterogenous structure” may particularly denote a structure composed of distinguishable portions composed of different materials, eventually in different state of aggregation (solid, liquid, gaseous), resulting in a heterogeneous physical body.
Embodiments of the present invention are now described with reference to the accompanying drawings. The invention is not limited to the illustrated or described embodiments.
The invention proposes now a newly designed component carrier, a first embodiment of which is shown schematically in
The component 13 comprises at least one electrically conductive surface 14, e.g. a pad or any other electrically conductive surface portion of the component 13, connected to an electrically conductive connecting element 15, which is extending from said electrically conductive surface 14 away from the stack 10, i.e. away also from the surface of the electrically insulating layer structure 12. Said electrically conductive surface 14 may be a portion of a wider conductive surface or may be a pad, optionally with a metal bump connected to said pad. In this example, the component 13 is located such, that the exposed surface of the component 13, which in the embodiment of
The connecting element 15 is configured to be connected to an external component 16, 17 to be mounted on the component carrier when at least one connecting surface 18, 19 provided in/on the external component 16, 17 is faced to the electrically conductive surface 14 of the component 13. In this position, electrically conductive structures 20 on the external components 16, 17 will also face the surface of the stack 10, in particular its electrically conductive layer structure 11. Structures 20 and structure 11 can be electrically connected by soldering, sintering, connection via a metal (copper pillar) or in any other suitable manner, symbolized in
As “facing the at least one connecting surface 18, 19 provided in/on the external component 16, 17 to the electrically conductive surface 14 of the component 13” it is meant that the two surfaces are at least partially overlapped from a frontal view perpendicular to one of the main surfaces of the component carrier, meaning that along the stack thickness direction (z-direction) a portion, preferably the majority, of the two surfaces overlaps one to each other; in other words, at least a portion between the at least one connecting surface 18, 19 provided in/on the external component 16, 17 and the electrically conductive surface 14 of the component 13 are aligned along the thickness direction of the stack (z-direction) so that they can be electrically connected by the electrically conductive connecting element, the latter preferably extending along a vertical direction (perpendicular to one of the main surfaces of the component carrier). In addition, the external components 16, 17 may have connection pads or other electrically conducting structures on their sides other than that facing the component 13 or the stack 10, respectively, e.g. on the opposite site of the connecting surface.
After accomplishing the electrical and also mechanical connection between the stack 10 and the external components 16, 17, a package comprising these elements 10, 16, 17 is at least partially formed. The final package might also have a heat removal structure on top of the external components (not shown). Most preferred, the explanations above and in the following, referring to the electrical connection elements 15 and their specific construction and design also apply to the connection elements 22 of the external components 16, 17.
It should be mentioned that
As can also be gathered from
Alternatively, at least one connection element 15 is made of a heterogeneous conductive structure, while the rest can be standard solder balls. Also a mixture of different kinds of heterogeneous structures is possible, e.g. the group of connection elements 15 consisting of nano wires and porous structures, of solder balls with rubber particles and nanowires, and so forth.
With these features, a reliable connection of the component 13, preferably a bridge, with the external components 16, 17 can be assured even in case of slight planar misalignment (relaxed to x-y and/or to z-tolerances), also compensating for CTE (coefficient of thermal expansion) mismatching. Further, there is a direct connection between the component 13 of the stack 10 and the external component 16, 17, with no need to embed the component anymore. At least, solder material can be avoided and potentially increase of the ICS-to-chip interconnection reliability is possible, as well as redundant connection between component 13 and external components 16, 17.
The connecting element 15, 22 may be permanently or at least temporarily deformable, where the deformation is at least one of a compression, elongation, shearing or bending. According to a first group of preferred embodiments of the invention, depicted in
Most preferred, a damping structure 27, for instance an insulating material, preferably comprising a spongy structure, is provided between the component 13 and the stack 10. This allows a damped displacement of the component 13 and the external components 16, 17 connected thereto with respect to the stack 1. There may be provided free space between the sidewalls of the component 13 and the stack 1. This may have the advantage that the damping structure 27 can expand into this free space and/or can compensate the alignment misalignment between the component, the external component(s) and the component carrier as above and/or within the values above described Alternatively no free space provided and the damping structure 27 internally compensates the stresses (pressure or shear).
Another possible embodiment regarding the arrangement of the component 13 with respect to the stack 10 is also shown in
Below the damping structure 27 there could be provided an additional conductive structure (not shown) at the bottom of the recess in the electrically insulating structure 12 of the stack. Component 13 could also be electrically connected to such additional electrically conductive structure, which could be a copper layer.
Further,
While the embodiments of
Another possible embodiment regarding the arrangement of the component 13 with respect to the stack 10 is shown in
The solder bumps 29 can have different sizes for the connection elements 15 of the component 13 and for the connection elements 35 of the stack 10 itself, to compensate for possible thickness differences as for instance in the embodiment shown in
A still further embodiment of the invention is shown in
It must also be mentioned that the copper pillars 34 or every other pillar structure in every arrangement and on every component or layer structure may be embedded in the component 13 or any other component or layer structure.
This heterogeneous structure can comprise a liquid metal structure connected to the electrically conductive surface. As shown in the exemplary embodiment of
The present invention as explained in the preceding paragraphs can overcome the disadvantages of the prior art by a connection where the damping effect is obtained by the dimensions (nanowires) and/or the materials (other alternatives) of the contacting protruding elements.
As already resulting from the above description, the connecting element arrangement of a complete package 10, 16, 17 of a stack 10 of a component carrier and at least two external components 16, 17 comprises two further elements, a first element 15 connected to the at least one electrically conductive surface 14 of the component 13 and a second element 22 connected to the at least one connecting surface of the external components 16, 17, respectively. Said two elements 15, 22 being connected one to each other providing the electrical connection between the at least one electrically conductive surface 14 of the component 13 with the at least one connecting surface of the external component 16, 17. Preferred, the two elements 15, 22 are connected one to each other at their respective front-end sections, as can be best seen in
Another embodiment according to the invention comprises two elements 15, 22 that are connected one to each other by the at least partial intertangle of the nanowires 23 of the first element 15 with the nanowires 24 of the second element 22, as shown in the microscopic picture of
A still further embodiment comprises a connecting element 15 and/or a first element and/or a second element that is deformed at the contact portion with the respective at least one electrically conductive surface 14, 18, 19 or at least one connecting surface or the opposing first or second element. Preferred, the at least one electrically conductive surface 14 of the component 13 and the at least one connecting surface 18, 19 of the external components 16, 17 are solely connected one to each other by the connecting element, 15, 22.
According to a further embodiment of the invention, the connecting element 15, 22 and/or the first element and/or the second element advantageously may at least be partially covered by a protecting material, and/or an underfill structure 36 can be provided between the component 13 and at least one of the external components 16, 17, preferably between the complete stack 10 and all external components 16, 17.
Another embodiment according to the invention is characterized in that the stack comprises at least one exposed electrically conductive surface on the main surface where the component is exposed, said at least one exposed electrical conductive surface being connected to an external conductive structure extending from the at least one exposed electrical conductive surface and configured to expose a surface at an higher vertical level than that of the at least one exposed electrical conductive surface.
The package 10, 16, 17 may also be further protected by a top mounted rigid lid (not shown) at the side of the stack 10 with the external components 16, 17, or alternatively, by an overmould structure 37 as shown in
Number | Date | Country | Kind |
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23194160.0 | Aug 2023 | EP | regional |