Arrangement and method for heat management of heat and pressure induced lamination of a panel

Abstract

An arrangement and method for performing thermal management during a heat and pressure induced lamination process of panels (130) in a pressbook stack (100) for manufacturing a component carrier (550) is disclosed. The arrangement's pressbook stack (100) comprises: (a) two heating plates (110); (b) a stack of a plurality of panels (130) placed between the heating plates (110); (c) a plurality of separators (120) located between adjacent panels (130) of the stack; (d) a plurality of heat conducting structures (560, 660, 760) arranged in and / or at the panels (130, 530, 630, 730). The heat conducting structures (560, 660, 760) are configured such that a temperature distribution within a respective panel (130, 530, 630, 730) and / or a space between different panels (130, 530, 630, 730) is at least partially changed.

Description

Technical Field

[0001] The present invention generally relates to the technical field of producing component carriers having laminated panels. In particular, the present invention relates to a technique for laminating panels in a so-called press book arrangement, wherein a plurality of panels are sandwiched between two externally heated plates and a separator sheet is arranged between each two panels. Background Art

[0002] A component carrier, such as a printed circuit board (PCB), is a supporting structure for at least one electronic component that forms an electronic assembly or circuit. A component carrier comprises a layer combination of at least one electrically insulating or dielectric layer structure and at least one electrically conductive layer structure, typically made of metal, such as copper. This layer combination is also referred to as a panel.

[0003] The conductor traces representing the interconnection wiring are formed by appropriately structuring or patterning an electrically conductive layer structure disposed on top of or below the electrically insulating layer of the component carrier. Electronic components can be mounted on the upper or lower surface of the component carrier. In some applications, the electronic components are at least partially embedded within (the volume of) the component carrier.

[0004] A multilayer component carrier is a laminate panel comprising a plurality of (patterned) electrically conductive layer structures and a plurality of electrically insulating layer structures or dielectric layer structures in an alternating sequence. In order to electrically connect the different electrically conductive layer structures, metallized vias extending through at least one electrically insulating layer may be used.

[0005] An effective way to produce laminated panels is the so-called book-pressing technology, in which a stack is arranged between two heating plates, the stack comprising a plurality of panels separated from each other by a corresponding separator. By heating the heating plate, the temperature in the stack rises. In addition, by compressing the heating plate, the stack is pressurized and a heat-pressure-assisted lamination process is performed. The process can be repeated with an (expanded) panel comprising a previously laminated panel and one or two additional electrical insulation layer structures or dielectric layer structures, the one or two additional electrical insulation layer structures or dielectric layer structures being arranged above the previously laminated panel and / or below the previously laminated panel. Similarly, a corresponding separator must be arranged between the two (expanded) panels.

[0006] Due to the increasing miniaturization of electronic components, there is a trend towards thinner component carriers. Therefore, thin laminate panels must also be provided. For reasons of efficiency, the above-mentioned booklet-pressing technology should still be used.

[0007] When only thin panels are laminated, the resulting panel structure often exhibits warping, which is generally associated with the low stiffness of the thin panels. These warping issues become increasingly severe as the panel thickness decreases.

[0008] It may be desirable to reduce the warpage of panels used to manufacture component carriers. Summary of the Invention

[0009] This need can be met by some embodiments according to the present invention. Advantageous embodiments of the present invention are described below.

[0010] According to a first aspect of the present invention, there is provided an arrangement for performing thermal management during a heat and pressure induced lamination process of panels in a book stack for manufacturing a component carrier, wherein the book stack comprises: (a) two heating plates; (b) a stack of a plurality of panels, the stack of panels being positioned between the heating plates; (c) a plurality of separators positioned between adjacent panels of the stack; and (d) a plurality of heat-conducting structures arranged in and / or at the panels. The heat-conducting structures are configured to at least partially vary a spatial temperature distribution within a respective panel and / or between different panels.

[0011] The arrangement described is based on the idea that a major cause of undesirable warping of panels, in particular thin panels, is a non-optimal temperature distribution within the book stack during the heat- and pressure-assisted lamination process. Since the curing process associated with lamination depends largely on the temperature of the material to be cured, an unsuitable temperature distribution generally leads to an uneven degree of curing. It has been found that such an uneven degree of curing, in which the degree of curing varies in particular within or along the main plane of the panel / component carrier, is a direct cause of the undesirable warping. However, it should be mentioned that spatial temperature variations perpendicular to the main plane of the panel may also lead to uneven curing and thus to undesirable warping.

[0012] Descriptively speaking, with the described thermal management of the laminate, electrically insulating or dielectric layer structures, such as prepregs, can be cured more uniformly. This results in less internal stress, which in turn leads to less warping of the panel and, of course, also to less warping of the component carrier produced from the laminate panel by a suitable singulation process.

[0013] It should be noted that during the thermally assisted lamination process involving the mentioned curing, the temperature distribution may vary over time. In this case, it should be appreciated that each thermal treatment certainly requires a certain ramp-up phase in order to bring the temperature of the material to be cured to the desired temperature. In most applications, a temperature ramp-down phase will also occur after the desired temperature has been maintained for a certain or predetermined period of time. In this case, it has been found that the spatial temperature variations within the material to be cured are particularly large during the temperature ramp-up phase of the lamination process. Therefore, the described heat-conducting structure should be configured to provide such a heat flow: this heat flow changes the spatial temperature variations, in particular the spatial temperature variations during such ramp-up phase. This can be achieved by a short thermal response time, which means that even relatively small temperature variations are equalized in a rapid manner. Such a short thermal response time can be achieved by selecting a material comprising a large thermal conductivity for the heat-conducting structure.

[0014] Preferably, in the described book-pressed stack, a separator is positioned / sandwiched between each pair of two adjacent or neighboring panels.Similarly, the same applies to the heat-conducting structures, wherein preferably at least one heat-conducting structure is provided for each panel.

[0015] The described heat-conducting structure can be inserted into or embedded in the panel. Alternatively or in combination, the heat-conducting structure can be arranged at the surface of the panel. In this case, the heat-conducting structure can be assigned to the panel or to the corresponding separator. This means that: when the stack of panels is assembled with the separator located between the (adjacent) panels, the heat-conducting structure can be attached to the panel or to the separator. When attached to the panel, the heat-conducting structure can form part of the final laminated panel. When attached to the separator, the heat-conducting structure can remain at the separator. After adding additional (uncured) electrically insulating layer structures or dielectric layer structures, in particular prepreg structures, to the previously laminated panel to increase the number of layers, the heat-conducting structure attached to the separator can then be used to change the spatial temperature distribution in the additional dielectric layer structure / prepreg structure added during the next curing process in a suitable manner, which ultimately leads to reduced warping.

[0016] This modification of the temperature profile by dedicated thermal management can—if applicable based on simulation results—allow the highest temperature to be achieved in a specific area or zone of the respective panel as the optimal curing temperature. Consequently, the contribution of this area / zone to the resulting overall warpage of the component carrier is minimized.

[0017] The goal of the (optional) simulation mentioned above is to find a way to counteract the warping by directing the thermal energy within the book press to predetermined areas / regions or panels.

[0018] Said change in temperature direction may be performed primarily within the stamped piece along the z direction, i.e. from the outer panel to the inner panel, and secondly across the panels in the x / y direction close to the areas / zones most requiring thermal energy and / or away from the areas / zones most sensitive to thermal energy.

[0019] According to an embodiment of the invention, the heat conducting structure is configured such that the spatial temperature distribution within a respective panel and / or between different panels is at least partially homogenized.

[0020] The described temperature homogenization is probably the simplest option for temperature variation, yet produces good results for warpage reduction. The corresponding simulations related to the thermal management for achieving the at least partial temperature homogenization can be implemented with relatively simple algorithms.

[0021] According to another embodiment of the present invention, the heat conducting structure includes a thermal via.

[0022] The thermal vias may extend in a direction perpendicular to the main plane of the corresponding panel. Thus, the thermal vias improve the thermal conductivity between different adjacent panels within the stack (along the z-direction). Specifically, the thermal vias formed in a particular panel may improve the thermal conductivity, in particular the thermal conductivity between the particular panel and the panel formed above the particular panel and the panel formed below the particular panel. In other words, the vias formed in a particular panel may improve the thermal conductivity between the panel below the particular panel and the panel above the particular panel. Of course, the thermal vias may also increase the thermal conductivity, possibly to a lesser extent, within the plane of the corresponding panel, i.e., along the x-direction and / or y-direction perpendicular to the above-mentioned z-direction.

[0023] The thermal vias described may be similar to vias that are typically used to electrically interconnect different electrically conductive layers separated from each other by at least one electrically insulating / dielectric layer in a multilayer printed circuit board (PCB). However, according to the techniques described in this document, the vias are specifically used to conduct heat during the lamination process.

[0024] The vias described can be formed in a known manner by a mechanical drilling process and / or a laser drilling process. Thereafter, the vias are metallized or plated with metal, preferably copper. The metallization can cover the inner surface of the respective vias. Preferably, to improve thermal conductivity, the vias are completely filled with metal / copper.

[0025] The use of vias for improving thermal conductivity as described can provide the advantage that the heat conducting structure can be realized in a simple and efficient manner. Specifically, since the formation of vias is a process widely used in PCB manufacturing, the heat conducting structure can be realized by well-tried and proven via formation technology.

[0026] According to another embodiment of the invention, the heat conducting structure comprises a heat trace extending along one or both main surfaces of the panel. This may provide the advantage that the thermal conductivity, in particular the thermal conductivity along a direction in or parallel to the main plane of the respective panel, may be improved.

[0027] The described heat traces may be any heat conducting structures formed at the top and / or bottom surface of the respective panel. Furthermore, such heat conducting structures may also be formed at intermediate interfaces within two adjacent (dielectric) layers of the respective multilayer panel. Preferably, the heat conducting structure is a quasi-two-dimensional (2D) or flat metallization structure, which may be formed by patterning and / or structuring the electrically conductive layer structure and, of course, also the heat conductive layer structure. Such patterning or structuring processes are generally known from PCB manufacturing and are used to form conductor trace patterns, which are used, for example, to interconnect different electronic components of an electronic assembly formed at the PCB.

[0028] It should be noted that in order to set the appropriate thermal conductivity, not only the width of the heat trace can be adjusted, but also the thickness of the heat trace. In addition, by selecting the appropriate direction of the heat trace, the desired directional characteristics of the improved heat conduction can be established, which can allow the heat conduction to be specifically directed into selected areas of the corresponding panel.

[0029] It should be mentioned that in most cases, the pattern of heat / metal traces that results in the desired spatial heat conduction along the plane of the respective panel does not correspond to the conductor paths that are later used to electrically connect the different components of the electronic assembly. Therefore, in the final (multi-layer) PCB, there may be: (a) metal traces that are primarily used to provide electrical conductivity; and (b) metal traces that are specifically used to provide heat conduction primarily along the respective traces into a specific spatial area and / or into a specific spatial direction of the respective panel.

[0030] According to another embodiment of the present invention, the heat-conducting structure includes a heat block embedded in the panel. Depending on the geometry of the heat block, the heat block can achieve improved thermal conductivity. Therefore, the degree of thermal conductivity can depend on the cross-sectional area of ​​the heat block along the corresponding direction of heat conduction. For clarity, the plane of the corresponding cross-sectional area is perpendicular to the corresponding direction of heat conduction.

[0031] By selecting suitable geometric dimensions for the heat block(s), the desired directional characteristics for improved heat conduction can be arranged such that when the heating plate is heated during the lamination process, an at least partially modified spatial temperature distribution is achieved, which can lead to an at least partially uniform curing behavior and to reduced warping at the end product "component carrier".

[0032] According to another embodiment of the present invention, the heat-conducting structures within the stack have a spatial distribution comprising: (i) a first spatial distribution of heat-conducting structures, which is assigned to a first panel of the stack; and (ii) a second spatial distribution of heat-conducting structures, which is assigned to a second, different panel of the stack. Thus, the second spatial distribution is different from the first spatial distribution. This allows for specific or individual adjustment of (spatial) heat conduction for each plane of the stack. Thus, the degree of curing can be homogenized not only along the (x and y) directions parallel to the principal plane, but also along the (z) direction perpendicular to the principal plane.

[0033] The described individual spatial distributions of the heat-conducting structures to the panel can allow for a precisely defined, improved heat flow throughout the stack (the entire volume of the stack). As will be explained in more detail below, based on a priori knowledge of the heat conduction within the stack, an appropriate distribution of the heat-conducting structures can be selected to achieve a desired uniform curing / hardening of the panel during the corresponding lamination process. This a priori knowledge can be obtained by thermal simulation and / or evaluation of previously manufactured component carriers using a book-type stack. Thus, artificial intelligence (AI) can be used to obtain knowledge of the relationship between different spatial distributions and the spatial curing degree distribution and / or the warping of the final PCB along a specific direction.

[0034] According to another embodiment of the present invention, (i) the first heat-conducting structure of at least one first layer of one panel and / or the first heat-conducting structure of the first panel is different in size, shape and / or orientation from (ii) the second heat-conducting structure of at least one second layer of the one panel and / or the second heat-conducting structure of the second panel.

[0035] Furthermore, the described panel-specific shape, size and / or orientation of the heat-conducting structure can allow for further homogenization of the degree of cure achieved by the lamination process. Again, to select a suitable shape, size and / or orientation, a priori knowledge can be used, which can be based on thermal simulations and / or AI assessments of the degree of cure, for example, with the aid of measured warpage.

[0036] According to another embodiment of the invention, the density of heat-conducting structures in the outer (circumferential or peripheral) areas of the same panel is greater than in the central area of ​​the panel. This may allow, in the case of most applications, a particularly effective homogenization of the temperature within the panel during heat-assisted lamination. The basic physical reason for this spatial temperature effect along the x- and y-directions mentioned above may be that, for geometrical reasons, the average (thermal) distance between the more central points of the panel and all the points of the two heating plates may be smaller than the average (thermal) distance between the outer "off-center" points and all the points of the two heating plates. Furthermore, the heat consumption / heat loss at the peripheral areas of the stack is generally greater than the heat consumption / heat loss in the central part of the stack.

[0037] According to another embodiment of the present invention, the density of heat-conducting structures in a panel that is centrally positioned in the stack (relative to the two heating plates) and / or at a panel that is centrally positioned in the stack (relative to the two heating plates) is greater than a panel that is positioned close to one of the heating plates. This can allow for particularly effective temperature homogenization within the panel during lamination in most applications. The basic physical reason for this effect along the z-direction mentioned above may be that the spatial distribution of the heat flow along the z-direction is non-linear. Descriptively speaking, the sum of the heat inputs originating from the two heating plates is not (also) constant along the z-direction. This can also apply to one or more time points during the thermally assisted lamination process.

[0038] According to another embodiment of the present invention, the arrangement comprises at least one of the following features (A) and (B).

[0039] (A): A first density of heat-conducting structures located in a first region of a panel associated with a component carrier to be manufactured is greater than a second density of heat-conducting structures located in a second region of the panel, wherein the second region is different from the first region.

[0040] (B): At least a portion of the heat-conducting structure is arranged in an area of ​​the panel outside the component carrier to be manufactured, for example, at least a portion of the heat-conducting structure is arranged in an area around the array of panels with component carriers to be manufactured and / or in an area between the array of panels with component carriers to be manufactured.

[0041] This density difference, described by feature (A), can provide the advantage that the temperature distribution will be preferentially modified / homogenized in those areas of the panel corresponding to the final product, i.e., the (singularized) component carrier. Thus, the difference between the second density and the first density can be a compromise between (a) a relatively small total number of heat-conducting structures and (b) a desired minimum temperature homogenization. In this case, it may be advantageous to keep the number and / or amount of heat-conducting structures employed relatively small, as heat-conducting structures that are not actually required in practice lead to reduced costs. In some use cases, the second density can be zero over or within at least some sub-areas of the second area.

[0042] Feature (B)—according to which the presence of a heat-conducting structure in a region of the panel outside the component carrier to be manufactured—can narrow the temperature distribution within or along the entire corresponding panel. Undesirable warping of the manufactured component carrier, which could result from warping of (wasted) regions outside the component carrier to be manufactured, can thus be minimized.

[0043] According to another embodiment of the present invention, the heating plate and / or the separator are at least partially made of a material having a thermal conductivity of at least 100 W / mK, in particular, the heating plate and / or the separator are at least partially made of a material having a thermal conductivity of at least 200 W / mK. This can narrow spatial temperature variations within the heating plate and / or separator itself.

[0044] In this context, it should be understood that a heating plate having an at least substantially uniform temperature distribution will contribute to a narrowing of the temperature distribution, particularly within panels positioned adjacent to the heating plate. In this context, it should be appreciated that, in the aforementioned repetitive book-pressing technique, it is primarily the outer panels positioned adjacent to the respective ones of the heating plates that are cured, since the inner panels have already been at least partially cured by means of the preceding lamination process. Therefore, the use of heating plates having the described high thermal conductivity can significantly contribute to improved curing and, therefore, to reduced warpage.

[0045] In some embodiments, the heating plate can be made of or include aluminum, copper, or copper-beryllium, wherein the heating plate includes a heating source, such as a heating wire arrangement, or is thermally coupled to a heating source, such as a heating wire arrangement. The same applies to at least some of the separators.

[0046] According to another embodiment of the invention, at least a portion of the separating sheet comprises active heating means.

[0047] The described active heating possibilities enabled by at least one separator (in addition to the heating plate) can allow for efficient modification / homogenization of the temperature profile within the stack, in particular along the Z-direction within the stack. Preferably, the different separators can be controlled independently, which can allow for the addition of heat input to selected areas within the stack.

[0048] The active heating device can be implemented using any suitable resistive heating element, such as a heating wire or heating trace. Furthermore, an inductive material, such as a ferromagnetic material, connected to a corresponding electromagnetic radiation source can also be used. In some embodiments, an electromagnetic radiation source is used that allows the emitted electromagnetic radiation to be specifically "focused" to the area of ​​the corresponding separator, or even specifically "focused" to a selected sub-area of ​​the corresponding separator.

[0049] According to another embodiment of the invention, the active heating means are arranged in the separator so that the peripheral portion of the separator is heated more strongly than the central portion of the separator. This can allow the above-mentioned effect of the typically lower temperature in the peripheral region of the panels of the stack to be actively compensated.

[0050] According to another embodiment of the invention, the arrangement further comprises a control unit configured for individually controlling the active heating devices such that the heat distribution within the respective panel and / or between different panels is at least partially varied.

[0051] In some embodiments, the control unit includes a temperature sensor, or the control unit includes an interface for a temperature sensor, which is arranged and configured to monitor the temperature of the stack. Therefore, for practical reasons, the temperature measurement may be limited to the outer surface of the stack or at least one outer surface portion of the stack. In this case, the temperature measurement can be achieved by infrared (IR) radiation emitted from the corresponding portion. This IT temperature measurement can be achieved with spatial resolution. Therefore, the active heating device can be controlled not only using one temperature measurement value, but also using two or even more temperature measurements. This can allow reliable temperature closed-loop control during the heat and pressure assisted lamination process.

[0052] According to another aspect of the present invention, a method for thermal management during a heat- and pressure-induced lamination process of panels in a book stack for manufacturing component carriers is provided. The provided method comprises: (a) placing a stack of panels between heated plates of the book stack, wherein separators are provided between adjacent panels of the stack; and (b) arranging heat-conducting structures in and / or at the panels such that, during the lamination process, the heat-conducting structures at least partially alter the spatial temperature distribution within the respective panels and / or between different panels.

[0053] Furthermore, the described method is based on the idea that by varying the temperature distribution within the book stack during the heat-assisted lamination process, undesired warping of the (thin) panels after curing can be significantly reduced.

[0054] The described thermal management of the book stack allows for the production of thin panels / component carriers with high quality and, in particular, low warpage. As the thickness decreases, the number of panels that can be included in the panel stack increases. In this context, it should be recognized that, for thermal reasons, the entire book stack typically has a maximum thickness. This is because, with increasing thickness, the panel positioned in the middle of the heating plate takes longer to reach a temperature sufficient to achieve the desired curing. Consequently, the heating time required for a successful lamination process increases, and the efficiency of component carrier production may decrease, even considering the greater number of panels that can be processed in a single lamination cycle.

[0055] According to one embodiment of the present invention, the method further includes: (a) simulating a temperature distribution for respective panels of the panel; and (b) controlling a manufacturing unit for manufacturing the panel based on the simulated temperature distribution, wherein the manufacturing unit arranges heat-conducting structures within and / or at the respective panels to modify the simulated temperature distribution. This can allow for finding and / or implementing an arrangement (distribution) of the heat-conducting structures that can result in an optimal spatial variation of temperature during the heat-assisted lamination process, which variation results in minimal warping of the final component carrier.

[0056] The simulation described may employ an algorithm that takes into account at least one thermal model of the stack. Thus, not only the total number of panels in the stack may be considered, but also the number of panels that have already been cured. This may be because already cured panels "consume less heat" because heat-consuming cross-linking has already occurred in the already cured or hardened (resin) material.

[0057] The thermal model can include the specific heat capacity and / or latent heat number of at least some of the materials of the stack. With regard to the specific heat capacity, the thermal model employed can particularly take into account the (patterned) metal layers, for example, made of copper, included in the panel. The thermal model can rely solely on the total specific heat capacity and / or latent heat number of the materials of the entire stack. The thermal model can more accurately account for the spatial distribution of the respective materials. This can be advantageous, particularly for the copper traces on the final component carrier that electrically connect the various components of the electronic assembly, including the final component carrier and these components mounted thereon.

[0058] It should be noted that in this context, the term "arrangement" or "arrangement" can be understood broadly. Specifically, "arrangement" can refer to the spatial distribution of the heat-conducting structures within and / or at the respective panels. This means that the density of the heat-conducting structures is a relevant parameter. Furthermore, the orientation, shape, and / or size of the heat-conducting structures arranged within and / or at the respective panels can be controlled by the manufacturing unit to achieve a change in the temperature distribution, thereby reducing warpage of the singulated component carrier.

[0059] According to another embodiment of the present invention, the manufacturing unit is controlled based on control parameter values ​​obtained using an artificial intelligence (AI) algorithm. Thus, based on training and (warpage) measurement data of the final, singulated component carrier, an improved spatial arrangement (e.g., distribution, orientation, shape, size) of the heat-conducting structures is determined. Thus, the described arrangement of the heat-conducting structures can be determined and / or implemented in an at least partially automated manner.

[0060] It should be noted that embodiments of the present invention have been described with reference to different subject matters. In particular, some embodiments have been described with reference to method-type claims, while other embodiments have been described with reference to apparatus-type claims. However, those skilled in the art will appreciate from the above and following descriptions that, unless otherwise indicated, any combination of features relating to different subject matters, in addition to any combination of features belonging to one subject matter, and in particular any combination of features from a method-type claim with features from an apparatus-type claim, are considered to be disclosed with reference to this document.

[0061] In the following, features of further embodiments of the invention are described. Furthermore, general considerations regarding the technology for component carrier production and the use of component carriers are presented, which may enhance the understanding of the invention.

[0062] In the context of the present application, the term "component carrier" may particularly denote any support structure capable of accommodating one or more components on and / or in the component carrier to provide mechanical support and / or electrical connection. In other words, the component carrier may be configured as a mechanical carrier and / or an electronic carrier for the components. 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 board combining different types of component carriers of the types mentioned above.

[0063] In one embodiment, the component carrier comprises a (panel) stack of at least one electrically insulating layer structure and at least one electrically conductive layer structure. For example, the component carrier can be a laminate of the aforementioned electrically insulating layer structure and the electrically conductive layer structure, which have been formed using the so-called book-pressing technique of the present invention.

[0064] The component carrier obtained by singulating the individual panels can be a plate-like component carrier which can provide a large mounting surface for further components and yet be very thin and compact. The term "layer structure" may particularly denote a continuous layer, a patterned layer or a plurality of discontinuous islands in a common plane.

[0065] Plate-shaped component carriers can contribute to the compact design of electronic assemblies, wherein the component carrier nevertheless provides a large base for the components mounted thereon. In addition, bare chips (dies), in particular, as an example of embedded electronic components, can be easily embedded in thin boards, such as printed circuit boards, due to the small thickness of the bare chips.

[0066] The component carrier may be configured to include one of the following: a printed circuit board, a substrate (particularly an IC substrate), and an interposer.

[0067] In the context of this document, the term "printed circuit board" (PCB) may particularly denote a plate-like component carrier formed by laminating a plurality of electrically conductive layer structures with a plurality of electrically insulating layer structures using a book-pressing technique. As a preferred material for PCB technology, the electrically conductive layer structure is made of copper, while the electrically insulating layer structure may comprise resin and / or glass fiber, so-called prepreg, or FR4 material. The individual electrically conductive layer structures may be connected to each other in a desired manner by forming through-holes through the laminate, for example by laser drilling or mechanical drilling, and by filling these holes with electrically conductive material (particularly copper) to form vias serving as through-hole connections. In addition to being able to embed one or more components in the printed circuit board, the printed circuit board is typically configured to accommodate one or more components on one surface or two opposite surfaces of the plate-like printed circuit board. The one or more components may be connected to the corresponding main surface by soldering. The dielectric portion of the PCB may comprise a resin with reinforcing fibers (e.g., glass fibers).

[0068] In the context of the present application, the term "substrate" may specifically refer to a small component carrier. A substrate may be a component carrier that is relatively small relative to a PCB, on which one or more components may be mounted and may serve as a connection medium between one or more chips and another PCB. For example, a substrate may have substantially the same dimensions as the component (particularly an electronic component) to be mounted thereon (for example in the case of a chip size package (CSP)). More specifically, a substrate may be understood as a carrier for electrical connections or electrical networks and a component carrier comparable to a printed circuit board (PCB), but with a relatively high density of connections arranged laterally and / or vertically. Lateral connections are, for example, conductive paths, while vertical connections may, for example, be drilled holes. These lateral and / or vertical connections are arranged within the substrate and may be used to provide packaged components or unpackaged components (e.g., bare chips), in particular, IC chips and printed circuit boards or intermediate printed circuit boards. Therefore, the term "substrate" also includes "IC substrates." The dielectric portion of the substrate may be composed of a resin having reinforcing particles (e.g., reinforcing balls, in particular, glass balls).

[0069] The substrate or interposer may include or be composed of at least one layer of: glass; silicon (Si); a photosensitive or dry-etchable organic material, such as an epoxy-based laminate material (e.g., an epoxy-based laminate film); or a polymer compound, such as polyimide, polybenzoxazole, or benzocyclobutene-functional polymer.

[0070] In an embodiment, the at least one electrically insulating layer structure comprises at least one of the following: a resin (e.g., a reinforced resin or a non-reinforced resin, such as an epoxy resin or a bismaleimide-triazine resin), a cyanate resin, a polyphenylene derivative, a glass (particularly a glass fiber, a multilayer glass, a glass-like material), a prepreg material (e.g., FR-4 or FR-5), a polyimide, a polyamide, a liquid crystal polymer (LCP), an epoxy-based laminate film, a polytetrafluoroethylene (PTFE, Teflon), Ceramics and metal oxides. Reinforcement structures made of, for example, glass (multilayer glass) such as meshes, fibers or spheres may also be used. Although prepregs, especially FR4, are generally preferred for rigid PCBs, other materials, especially epoxy-based laminates or photosensitive dielectric materials, may also be used. For high-frequency applications, high-frequency materials such as polytetrafluoroethylene, liquid crystal polymers and / or cyanate ester resins, low-temperature co-fired ceramics (LTCC) or other low, very low or ultra-low DK materials may be implemented as electrically insulating layer structures in the component carrier.

[0071] In an embodiment, the at least one electrically conductive layer structure comprises at least one of the following: copper, aluminum, nickel, silver, gold, palladium and tungsten. Although copper is generally preferred, other materials or coated variants thereof, in particular coated with superconducting materials such as graphene, are also possible.

[0072] The components that can be embedded in the component carrier, preferably after singulation from a panel manufactured using the book-pressing technique, can be selected from the group consisting of: non-electrically conductive inlays, electrically conductive inlays (e.g., metal inlays, preferably comprising copper or aluminum), heat transfer units (e.g., heat pipes), light-guiding elements (e.g., optical waveguides or optical conductor connectors), optical elements (e.g., lenses), electronic components, or combinations thereof. For example, the components can be active electronic components, passive electronic components, electronic chips, memory devices (e.g., DRAM or other data memories), filters, integrated circuits, signal processing components, power management components, optoelectronic interface components, light-emitting diodes, optocouplers, voltage converters (e.g., DC / DC converters or AC / DC converters), cryptographic components, transmitters and / or receivers, electromechanical transducers, sensors, actuators, microelectromechanical systems (MEMS), microprocessors, capacitors, resistors, inductors, batteries, switches, cameras, antennas, logic chips, and energy harvesting units. However, other components can also be embedded in the component carrier. For example, magnetic elements can be used as components. This magnetic element can be a permanent magnetic element (e.g., a ferromagnetic element, an antiferromagnetic element, a multiferroic element, or a ferrimagnetic element, such as a ferrite core) or a paramagnetic element. However, the component can also be a substrate, an interposer, or another component carrier, such as in a plate-in-plate configuration. The component can be surface-mounted on the component carrier and / or embedded within the component carrier. Furthermore, other components, in particular components that generate and emit electromagnetic radiation and / or are sensitive to electromagnetic radiation transmitted from the environment, can also be used as components.

[0073] After the formation of the panel comprising the stack layer composition of the electrically insulating layer structure and the electrically conductive layer structure is completed, the obtained panel or singulated component carrier may be subjected to a surface treatment.

[0074] In particular, regarding surface treatment, an electrically insulating solder resist can be applied to one or both major surfaces of a panel or component carrier. For example, a solder resist layer can be formed over the entire major surface and then patterned to expose one or more electrically conductive surface portions that will be used to electrically couple the component carrier to an electronic peripheral. Surface portions of the component carrier that remain covered with solder resist, particularly those containing copper, can be effectively protected from oxidation or corrosion.

[0075] In terms of surface treatment, a surface treatment portion can also be selectively applied to the exposed electrically conductive surface portion of the component carrier. Such a surface treatment portion can be an electrically conductive covering material on the exposed electrically conductive layer structure (such as a pad, a conductive trace, etc., in particular including or consisting of copper) on the surface of the component carrier. If such an exposed electrically conductive layer structure is not protected, the exposed electrically conductive component carrier material (in particular copper) will be oxidized, thereby making the reliability of the component carrier lower. In addition, the surface treatment portion can be formed as a joint between a surface mounted component and a component carrier, for example. The surface treatment portion has the function of protecting the exposed electrically conductive layer structure (in particular copper circuit), and the surface treatment portion can realize a joining process with one or more components, for example by welding. Examples of suitable materials for the surface treatment portion are organic solderability preservative (OSP), electroless nickel immersion gold (ENIG), gold (in particular hard gold), chemical tin, nickel gold, nickel palladium, ENIPIG (electroless nickel immersion palladium immersion gold), etc.

[0076] The aspects defined above and other aspects of the invention are apparent from the examples of embodiment described hereinafter and are explained with reference to the examples of embodiment.The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 A book press stack is shown having two heating plates with alternating panels and separator sheets sandwiched between the two heating plates.

[0078] Figure 2 is a graph showing the temperatures measured at different locations at the heating plate during the lamination process.

[0079] Figure 3a 、 Figure 3b and Figure 3c The simulated (a) temperature distribution, (b) curing degree distribution, and (c) resulting panel warpage for different panels of a book stack are shown, respectively.

[0080] Figure 4a and Figure 4b Shown are (a) temperature distribution and (b) degree of cure distribution, respectively, simulated for different panels of a book stack having a heating plate made of aluminum.

[0081] Figure 5 Shown is a top view of a panel having (i) four quarter panels, each comprising an array of nine component carriers, and (ii) a plurality of heat-conducting structures implemented as thermal vias.

[0082] Figure 6 Shown is a top view of a panel having (i) four quarter panels, each comprising an array of nine component carriers, and (ii) a heat conducting structure made of thermal traces and thermal heat distribution pads.

[0083] Figure 7 A multilayer panel is shown in cross-section and includes a central core, two dielectric layers, two prepreg layers, and a plurality of embedded thermally conductive blocks.

[0084] Figure 8 A top view of a separator sheet with multiple individually controllable heating zones is shown. DETAILED DESCRIPTION

[0085] The illustrations in the accompanying drawings are schematic. It should be noted that in different drawings, similar or identical elements or features are provided with the same reference numerals or reference numerals that differ from the corresponding reference numerals only within the first digit. To avoid unnecessary repetition, elements or features that have already been explained with respect to previously described embodiments will not be explained again at a later point in the description.

[0086] Figure 1 A book stack 100 is shown, according to an embodiment of the present invention, configured for thermal management during a heat and pressure-induced lamination process. The book stack includes two heating plates 110. Heating devices embedded in and / or thermally connected to the heating plates 110 are not shown.

[0087] A paper pad 112 is disposed above the bottom heating plate 110 and below the top heating plate 110, respectively. A stack comprising a plurality of panels 130 and a plurality of separators 120 is disposed between the two paper pads 112. The panels 130 and separators 120 are arranged in an alternating manner such that one separator 120 is disposed between two adjacent panels 130. Separators 120 are also provided (a) between the uppermost panel 130 and the upper paper pad 112 and (b) between the lowermost panel 130 and the lower paper pad 112.

[0088] To narrow the temperature distribution along the main surface of the panel 130, the heating plate 110 and the separator 120 are made of a material having a high thermal conductivity of at least 100 W / mK. According to the embodiment described herein, the heating plate 110 and the separator 120 are at least partially made of aluminum.

[0089] Figure 2 is a graph showing the temperatures measured at twelve different locations at the heating plate during the lamination process. Specifically, Figure 2Six temperature curves for six positions at the upper heating plate and six temperature curves for six positions at the lower heating plate are shown in FIG. Due to the limited accuracy of the graph, it is not possible for the human eye to recognize all twelve temperature curves.

[0090] As from Figure 2 As can be seen, the temperature curve (as a function of time) indicated by the reference symbol "T" starts at room temperature. Over the course of the lamination process, the temperature increases to 200°C. A corresponding plateau is reached approximately 110 minutes after the start of the heat-assisted lamination process. 160 minutes after the start of the lamination process, heating is stopped and the temperature is lowered.

[0091] The measured temperature curves show that at every point in time, there is always a certain temperature difference between different locations on the heating plate. During the ramp-up phase, for example, approximately 60 minutes after the start of the lamination process, the maximum temperature difference is approximately 14 Kelvin (K). Even during the temperature plateau phase, the difference is around 5 K.

[0092] The inventors have recognized that each temperature difference has an influence on the degree of curing achieved by the heat- and pressure-assisted lamination process. Furthermore, they have recognized that different degrees of curing within the same panel lead to internal stresses and, therefore, undesirable warping of the component carriers obtained from the respective panels by the singulation process.

[0093] Figure 3a 、 Figure 3b and Figure 3c (a) Temperature distribution, (b) Curing degree distribution and (c) Panel warping resulting from simulations of different panels of a book press stack are shown, respectively. A book press stack having 22 panels has been simulated. The temperature distribution and the curing degree distribution are shown for panel No. 1 (P1), panel No. 11 (P11), panel No. 12 (P12) and panel No. 22 (P22). Therefore, panel P1 and panel P22 are positioned close to the upper and lower heating plates, respectively. The two panels P11 and P12 are positioned approximately in the central area between the two heating plates.

[0094] from Figure 3a and Figure 3b It can be seen that for panels P1 and P22, which are closer to one of the two heating plates, the temperature variations and cure extent variations along the main panel surface are relatively large. The corresponding temperature variations and cure extent variations for the "inner" panels P11 and P12 are smaller, but still significant.

[0095] from Figure 3cIt can be seen that the warping of panel P1 , which is “subjected” to a relatively large temperature variation, is more pronounced than the warping of panel P11 , which is “subjected” to a smaller temperature variation.

[0096] From these simulations, it is clear that good thermal management within the book stack can be an effective way to reduce unwanted warping. There are fundamentally many different possibilities for good thermal management within the book stack. For example, one possibility is to use heating plates and / or separators with higher thermal conductivity, which improves the temperature equalization along the major surfaces of the respective adjacent panels. Increased thermal conductivity can be achieved by changing the material of the heating plates and / or separators from, for example, steel (15 W / mK) to, for example, aluminum (≥200 W / mK), copper-beryllium alloy, or copper (≥400 W / mK).

[0097] Figure 4a and Figure 4b Figures 2 and 3 show (a) temperature distribution and (b) curing degree distribution for different panels of a book stack with a heating plate made of aluminum. Figure 3a and Figure 3b The corresponding simulation shown in Figure 3a and Figure 3b In the corresponding simulation shown in , a heating plate made of steel was used - the comparison shows that both the temperature variation and the degree of curing variation are significantly smaller. It should be clear that this leads to a reduction in the warpage of the final product "component carrier" / "PCB".

[0098] Figure 5 5 shows a top view of the panel 530. According to the exemplary embodiment described herein, the panel 530 has a layout structure with four areas, which are referred to as quarter panels 540. Figure 5 As can be seen, each quarter panel 540 comprises an array of nine component carriers 550 which can be obtained by a known singulation process after the (lamination) processing of the entire panel 530 is complete.

[0099] To reduce temperature changes, especially along Figure 1 The temperature variation in the z-direction extending between the two heating plates 110 of the book stack 100 shown in FIG. 1 is provided by providing a plurality of heat-conducting structures 560 that at least partially penetrate the panel along the z-direction. For the sake of clarity, it should be noted that the z-direction is described as being perpendicular to the main surface of the panel 530, which is defined by the x-direction and the y-direction. According to the exemplary embodiment described herein, the heat-conducting structures are (fully) metallized vias 560, preferably made of copper.

[0100] As from Figure 5 As can be seen, all thermal vias 560 are located in an area outside of the quarter panel 540. This can provide the following advantage: the thermal vias 560 do not interfere with possible electrical conductor structures, such as electrical conductor tracks and / or electrical vias, which may be present in or at the (multi-layer) component carrier 550 in order to provide the required circuits for the electronic components of the electronic assembly. However, it should be mentioned that in other embodiments, the thermal vias can also be located in the area of ​​the component carrier 550 or at least close to the area of ​​the component carrier 550.

[0101] Figure 6 A top view of a panel 630 is shown, which also includes four quarter panels 540, each of which includes an array of nine component carriers 550. According to the exemplary embodiment described herein, a plurality of quasi-two-dimensional heat-conducting structures 660 are provided at the main surface of the panel, which improve the temperature equalization along the main plane of the panel 630, i.e., a plane parallel to the plane of the drawing.

[0102] As from Figure 6 As can be seen, the heat-conducting structure 660 includes a thermal heat distribution pad 662 located in the central portion of the major surface of the panel 630. In addition, the heat-conducting structure 660 includes (four) heat traces 661 that are thermally coupled to the pad 662 and allow heat to flow from the central portion of the pad 662 toward the peripheral area of ​​the panel 630. Since the temperature in the central portion of the panel 630 is higher than the temperature at the outer areas in most scenarios, this heat flow from the central portion outward along the heat traces 661 will result in a significant improvement in the temperature equalization along the major surface of the panel 630.

[0103] It should be mentioned that, depending on the specific application, the shape of the heat conducting structure may be different from Figure 6 6, along with the shape of the thermal trace 661. For example, the heat-conducting structure, and in particular the central heat-distributing pad, can include or consist of, for example, but not limited to, the following: (i) a circular portion; (ii) an elliptical portion; (iii) a rectangular portion; and (iv) a portion defined by a polygon. The specific shape of the heat-conducting structure can depend on the final component carrier layout.

[0104] Figure 7A multilayer panel 730 is shown in cross-section and includes a central core 732 that has already been cured. Two dielectric layers 734 are formed above and below the core 732, which may have been at least partially cured from prepreg layers during a (previous) lamination process. Thus, the dielectric layers 734 may be referred to as "post-lamination dielectric layers." Two uncured or unlaminated dielectric layers 736 are provided above the upper dielectric layer 734 and below the lower dielectric layer 734. Accordingly, these dielectric layers 736 may be referred to as "pre-lamination dielectric layers." Generally speaking, the dielectric layers 734 are dielectric layers that have already undergone at least one lamination step, and in particular, one more lamination step than the dielectric layers 736.

[0105] Multilayer panel 730 further includes a plurality of thermally conductive blocks 760 embedded within dielectric layer 734 and dielectric layer 736. According to the exemplary embodiment described herein, these blocks 760 are made of copper having a specific high thermal conductivity of approximately 400 W / mK.

[0106] It should be clear that the presence of these blocks 760 improves the desired temperature equalization. Therefore, the strength of the temperature equalization depends on the size of the blocks 760. The preferred direction of the temperature equalization depends on the shape and / or orientation of the blocks 760.

[0107] The heat block 760 disposed within the dielectric layer 734 has already improved temperature equalization during a previously completed lamination process in which the previous prepreg layer has already been cured into the dielectric layer 734, and in which the dielectric layer 736 was not yet present. The heat block 760 disposed within the dielectric layer 736 will become effective during a subsequent lamination process in which the prepreg layer 736 will also be cured.

[0108] As from Figure 7 As can be seen, the number / density of heat blocks 760 differs between layers 734 and 736. The distribution of heat blocks 760 within the different layers 734 and 736 can be selected based on a priori knowledge of the heat conduction within the entire printed stack. As mentioned above, this a priori knowledge can be obtained through thermal simulations and / or evaluation of the warpage of previously manufactured component carriers. Thus, artificial intelligence (AI) can be used to gain knowledge of the relationship between different spatial distributions and the spatial curing distribution and / or the warpage of the final PCB along a specific direction.

[0109] As from Figure 7It can further be seen that the density of the thermally conductive blocks 760 is greater in the outer region of the panel 730 compared to the central region of the panel 730. This may allow for particularly effective temperature homogenisation within the panel during heat-assisted lamination in most applications.

[0110] Figure 8 820. The separator 820 includes a plurality of heating zones 821 and 822. According to the exemplary embodiment described herein, the heating zones 821, 822 include a resistive material that can be heated by an electric current. Figure 8 It can be seen that the different resistive heating zones 821, 822 are individually electrically connected to the control unit 824. For ease of illustration, the electrical connection between the control unit 824 and the respective heating zones 821, 822 is schematically depicted using only a single dashed line, which of course requires two wires.

[0111] The control unit 824 is configured to control the current through the heating zones 821, 822 to at least partially homogenize the heat distribution, in particular to at least partially homogenize the heat distribution within the panel adjacent to the separator 820. The layout of the heating zones can be adapted to the specific application, for example by taking into account the above-mentioned prior knowledge based on thermal simulation and / or AI.

[0112] It should be noted that the term "comprising" does not exclude other elements or steps, and the use of the article "a" or "an" does not exclude a plurality. Elements described in connection with different embodiments may also be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

[0113] List of reference numerals:

[0114] 100 Book stacking pieces

[0115] 110 Heating Plate

[0116] 112 paper liner

[0117] 120 separator

[0118] 130 Panel

[0119] T Temperature at different locations on the top heating plate / bottom heating plate

[0120] ΔT Measured temperature difference

[0121] ΔT1 Measured temperature difference at the top heating plate

[0122] ΔT2 Measured temperature difference at the bottom heating plate

[0123] ΔT3 Temperature difference between heating plates

[0124] P1 Panel No.1

[0125] P11 Panel No.11

[0126] P12 Panel No.12

[0127] P22 Panel No. 22

[0128] 530 Panel

[0129] 540 Quarter Panel / Component Carrier Array

[0130] 550 Component carrier / PCB

[0131] 560 Thermal Conductive Structure / Thermal Via

[0132] 630 Panel

[0133] 660 heat conduction structure

[0134] 661 Thermal Trace

[0135] 662 Thermal Pad / Heat Distribution Pad

[0136] 730 Panel

[0137] 732 cores

[0138] 734 dielectric layer

[0139] 736 Uncured / Unlaminated Layers

[0140] 760 heat conduction structure / heat block

[0141] 820 separator

[0142] 821 Active heating elements / zones

[0143] 822 active heating elements / zones

[0144] 824 control unit.

Claims

1. An arrangement for performing thermal management during a heat and pressure induced lamination process of panels in a book stack for manufacturing a component carrier, wherein The book pressing stacking member comprises: two heating plates; a stack of multiple panels, the stack positioned between the heating plates; a plurality of dividers positioned between adjacent panels of the stack; and a plurality of heat-conducting structures arranged in and / or at the panels, wherein at least one heat-conducting structure is provided for each panel; wherein The heat conduction structure is configured such that the spatial temperature distribution within a respective panel and / or between different panels is at least partially modified by directing thermal energy within the pressed book stack to predetermined areas of the panel.

2. The arrangement according to claim 1, wherein: The heat-conducting structure is configured such that the spatial temperature distribution within the respective panel and / or between different panels is at least partially homogenized.

3. The arrangement according to claim 1, wherein: The heat conduction structure includes a thermal via.

4. The arrangement according to claim 1, wherein: The heat-conductive structure includes heat traces extending along one or both major surfaces of the panel.

5. The arrangement according to claim 1, wherein: The heat-conducting structure includes a thermal block embedded in the panel.

6. The arrangement according to claim 1, wherein: The heat conducting structures within the stack have a spatial distribution comprising: a first spatial distribution of the heat-conductive structures, the first spatial distribution being assigned to a first panel of the stack, and A second spatial distribution of the heat-conducting structures is assigned to a second, different panel of the stack, wherein the second spatial distribution is different from the first spatial distribution.

7. The arrangement according to claim 1, wherein: The first heat-conducting structure of at least one first layer of one panel and / or the first heat-conducting structure of the first panel is different in size, shape and / or orientation from the second heat-conducting structure of at least one second layer of the one panel and / or the second heat-conducting structure of the second panel.

8. The arrangement of claim 1, wherein: The density of said heat conducting structures is greater in the outer regions of the panel compared to the central region of the same panel.

9. The arrangement according to claim 1, wherein: The density of the heat-conducting structures is greater in and / or at a panel centrally located in the stack than in a panel located close to one of the heating plates.

10. The arrangement of claim 1, wherein: The arrangement includes at least one of the following features: (A) a first density of the heat-conducting structures positioned in a first region of the panel associated with the component carrier to be manufactured is greater than a second density of the heat-conducting structures positioned in a second region of the panel, wherein the second region is different from the first region; (B) At least a portion of the heat-conducting structure is arranged in a region of the panel outside the component carrier to be manufactured.

11. The arrangement according to claim 10, wherein: At least a portion of the heat conducting structure is arranged in a region around the array of panels with component carriers to be manufactured and / or in a region between the array of panels with component carriers to be manufactured.

12. The arrangement of claim 1, wherein: The heating plate and / or the separator are at least partially made of a material having a thermal conductivity of at least 100 W / mK.

13. The arrangement of claim 1, wherein: The heating plate and / or the separator are at least partially made of a material having a thermal conductivity of at least 200 W / mK.

14. The arrangement of claim 1, wherein: At least a portion of the separator sheet includes an active heating device.

15. The arrangement of claim 14, wherein: The active heating device is arranged in the separator sheet such that a peripheral portion of the separator sheet is heated more strongly than a central portion of the separator sheet.

16. An arrangement according to claim 14 or 15, wherein: The arrangement further comprises: A control unit is configured for individually controlling the active heating devices such that the heat distribution within the respective panel and / or between different panels is at least partially varied.

17. A method for performing thermal management during a heat and pressure induced lamination process of panels in a booklet stack for manufacturing a component carrier, the method comprising: placing a stack of panels between the heated plates of the book stack with separator sheets between adjacent panels of the stack; and Heat-conducting structures are arranged in and / or at the panels so that: during the lamination process, the spatial temperature distribution within the respective panel and / or between different panels is at least partially changed by means of the heat-conducting structures by directing thermal energy within the pressed book stack to predetermined areas of the panel, wherein at least one heat-conducting structure is provided for each panel.

18. The method according to claim 17, wherein The method further comprises: simulating the temperature distribution in corresponding ones of the panels, and A manufacturing unit for manufacturing the panels is controlled based on the simulated temperature distribution, wherein the manufacturing unit arranges the heat conducting structure in and / or at the respective panels so that the simulated temperature distribution changes.

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