Controlling the progress of material removal from component carrier structures during quality testing

Abstract

An apparatus (100) for processing a component carrier structure (102) for a quality test, the apparatus (100) comprising: a material removal unit (112) configured to remove material (102) of the component carrier structure to expose at least one test object (116) inside the component carrier structure (102) to be subjected to the quality test; a progress measurement unit (250) configured to measure the progress of the material removal of the component carrier structure (102); an analysis unit (252) configured to analyze whether the measured progress meets the requirements of a predetermined material removal objective; and a control unit (254) configured to control, based on the results of the analysis, whether the sequence of removing material, measuring the progress, and analyzing whether the measured progress meets the requirements of the predetermined material removal objective must be repeated.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method, a computer readable medium, and a program element for processing a component carrier structure for quality testing. [Background technology]

[0002] In the context of increasing product functionality of component carriers carrying one or more electronic components, the increasing miniaturization of such electronic components, and the increasing number of electronic components mounted on component carriers such as printed circuit boards, increasingly powerful array-like components or packages are being used that have several electronic components, which have multiple contacts or connections, with ever smaller spacing between these contacts. At the same time, component carriers should be mechanically robust and electrically reliable so that they can operate under harsh conditions.

[0003] Preparation and testing of cross sections of component carriers, surface-ground component carriers, and related objects has traditionally been performed manually by technicians. This applies to different types of microscopic specimens, such as cross sections and flat sections. However, this involves a great deal of effort and limited precision in terms of quality testing, which can be critical given the stringent requirements for throughput on an industrial scale.

[0004] The object of the present invention is to assess the quality of a component carrier structure with high reliability, high throughput and reasonable effort.

[0005] In order to achieve the above-defined objects, an apparatus and method, a computer readable medium and a program element for processing a component carrier structure for quality testing are provided according to the independent claims.

[0006] According to an exemplary embodiment of the present invention, there is provided an apparatus for processing a component carrier structure for a quality test, the apparatus comprising: a material removal unit configured to remove material of the component carrier structure to expose at least one test target inside the component carrier structure to be subjected to the quality test; a progress measurement unit configured to measure progress of the material removal of the component carrier structure; an analysis unit configured to analyze whether the measured progress satisfies a predetermined material removal objective; and a control unit configured to control, based on a result of the analysis, whether the sequence of removing material, measuring the progress, and analyzing whether the measured progress satisfies the predetermined material removal objective must be repeated. Specifically, the control unit may iteratively repeat the sequence of removing material, measuring the progress (i.e., material removal), and analyzing whether the measured progress satisfies the requirement one or more times until the predetermined material removal objective is achieved.

[0007] According to another exemplary embodiment of the present invention, there is provided a method for preparing a component carrier structure for a quality test, the method comprising the steps of removing material of the component carrier structure to expose at least one test target inside the component carrier structure to be subjected to the quality test, measuring a progress of the material removal of the component carrier structure, analyzing whether the measured progress satisfies a predetermined material removal objective, and controlling based on a result of the analysis whether the sequence of removing material, measuring the progress, and analyzing whether the measured progress satisfies the predetermined material removal objective has to be repeated. In particular, the method may comprise iteratively repeating the sequence of removing material, measuring the progress, and analyzing whether the measured progress satisfies the requirement one or more times until the predetermined material removal objective is achieved.

[0008] According to yet another exemplary embodiment of the present invention, there is provided a program element (e.g., a software routine in source code or executable code) which, when executed by a processor (such as a microprocessor or CPU), is adapted to control and / or perform a method having the above-described features.

[0009] According to yet another exemplary embodiment of the present invention, there is provided a computer readable medium (e.g. a CD, DVD, USB stick, SD card, floppy disk or hard disk or any other (particularly smaller) storage medium) on which is stored a computer program which, when executed by a processor (such as a microprocessor or CPU), is adapted to control and / or carry out a method having the above features.

[0010] Data processing that can be performed according to embodiments of the present invention can be realized by a computer program, i.e., by software, or by using one or more special electronic optimization circuits, i.e., hardware, or in a hybrid configuration, i.e., by software and hardware components.

[0011] In the context of the present application, the term "component carrier" may refer to any support structure capable of housing one or more components thereon and / or therein, in particular to provide mechanical support and / or electrical connectivity and / or optical connectivity and / or thermal connectivity. In other words, the component carrier may be configured as a mechanical and / or electronic carrier for the components. Specifically, 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 that combines different of the above-mentioned types of component carriers.

[0012] In the context of the present application, the term "component carrier structure" may specifically refer to a component carrier, e.g., a panel, an array, or a thin sheet that is handled and processed during and / or after the manufacture of the component carrier itself. Thus, a component carrier structure may specifically refer to a panel including multiple connected preforms of a component carrier, an array including multiple connected preforms of a component carrier (such as a quarter panel), a preform of a component carrier (i.e., a component carrier that is not yet easily manufacturable), or a component carrier that is easily manufactured (such as a printed circuit board (PCB) or integrated circuit (IC) substrate). However, it is also possible that the component carrier structure is a coupon.

[0013] In the context of the present application, the term "quality test" may specifically refer to the evaluation of the quality of a component carrier structure by analyzing one or more predetermined test target characteristics of the component carrier structure. Such a quality test may test whether one or more such characteristics of the component carrier structure meet one or more quality criteria. Such quality criteria may include one or more qualitative quality criteria (e.g., the presence or absence of delamination of a layer structure as a qualitative error pattern or failure scenario) and / or one or more quantitative quality criteria (e.g., the thickness of a patterned copper layer relative to a predetermined range of acceptable thicknesses). Examples of determinable quality defects of a component carrier structure include artifacts related to drill holes, hair inclusions, soldermask effects, shorts between conductive traces that should be separated, etc. For example, a quality test of a component carrier structure may be performed to check whether the component carrier structure complies with industry standards (e.g., IPC 6012, IPC-A-600, IPC-2221, etc.).

[0014] In the context of the present application, the term "predetermined test object" may specifically mean an internal structural feature of a component carrier structure exposed by material removal, which is predetermined as a characteristic item for evaluating the quality of the component carrier structure. For example, the test object may be a drill hole or a layer structure in a (particularly laminated) layer stack of a component carrier structure having at least one conductive layer structure (e.g., a patterned copper foil and / or copper-filled laser vias) and / or at least one electrically insulating layer structure (e.g., a sheet containing a resin, such as an epoxy resin, and optionally reinforcing particles, such as glass fibers). Specifically, the at least one testable characteristic or attribute of the component carrier structure may include one or more of the diameter of the drilled holes (e.g., laser-drilled or mechanically drilled holes, which may or may not be filled with a conductive material such as copper), the distance between adjacent drilled holes, the thickness of the layer structure (e.g., the thickness of the patterned copper foil or layer), the planarity of the layer structure (e.g., measured by deviation of the layer structure from a purely planar configuration), delamination of the layer structure (i.e., for example, a layer structure that is at least partially separated from an integral set of stacked layer structures), etc.

[0015] In the context of the present application, the term "measuring the progress of material removal" may specifically mean detecting information indicative of how far a process of removing material from a component carrier structure has progressed. This may be, for example, measuring the amount of material removed from the component carrier structure, detecting a changed position of the outer edge of the component carrier structure in terms of material removal, detecting a changed position of a material removal unit or tool affecting the component carrier structure to remove material therefrom, detecting sensor data (e.g., contact pressure, feed rate and / or rotation speed) indicative of the impact of a material removal unit on the component carrier structure, detecting a change in sensor data sensed on a sacrificial structure and / or on a test object of the component carrier structure in terms of material removal (e.g., but not limited to, abrasive removal), etc.

[0016] In the context of the present application, the term "predetermined material removal objective" may specifically refer to the target exposure (e.g., exposing the maximum cross-sectional area) of at least one test target (e.g., a drill hole) of a component carrier structure that is desired in the context of a quality test. The purpose or goal of the preparation process defined by the predetermined material objective may be to expose one or more test targets of the component carrier structure and enable meaningful quality testing of the component carrier structure by analyzing the so-exposed test targets. For example, the predetermined material removal objective may be to expose a target inspection surface of interest of the component carrier structure that shows at least one test target in a predetermined configuration (e.g., showing the maximum diameter of a drill hole). In the context of the present application, the term "removing material to expose a plane" may specifically refer to material removal in a horizontal, vertical, or diagonal direction of the component carrier structure. Thus, the exposed surface may have any direction (e.g., horizontal, vertical, or diagonal).

[0017] In the context of this application, the term "iteratively repeating a sequence of material removal, progress measurement, and analysis" may specifically mean repeating the sequence of steps described above one, two, three, or even more times until the measured progress of material removal then indicates that the above-mentioned material removal objective has been achieved.

[0018] According to an exemplary embodiment of the present invention, there is provided a system for testing the quality of a component carrier structure (such as a printed circuit board structure or a preform thereof), in which a portion of the material of the component carrier structure can be removed by a polishing process (such as grinding) to expose an internal flat surface of interest in order to allow external access to at least one test object for testing its properties and thus the quality of the component carrier structure. Furthermore, the progress of the material removal process can preferably be measured by a corresponding progress measurement unit during (and / or after) said polishing process. The measured progress can be compared with a predetermined material removal objective (e.g., whether the polishing process has exposed a quality test object of interest, e.g., a cross-section of the center of a drill hole). If the predetermined material removal objective has not yet been achieved, as indicated by the measured progress, the sequence of material removal, progress measurement, and analysis of the measured progress with respect to the predetermined material removal objective can be iteratively repeated until the progress measurement indicates that the material removal objective has finally been achieved. The processed component carrier structure is then ready for image detection, determination of said test object, and evaluation of the properties of said test object with respect to the quality test. Highly advantageously, the described process is fully automated, thereby increasing throughput (compared to conventional manual processing of component carrier structures) and meeting stringent industrial-scale requirements. Automated progress measurement and analysis relative to predetermined material targets can significantly improve the accuracy of the automated process (compared to conventional automated processing of component carrier structures). Thus, exemplary embodiments of the present invention may enable the quality of component carrier structures to be assessed with high reliability, high throughput, and reasonable effort.

[0019] The above-described repetition of the sequence of steps described above may need to be performed in many cases, and therefore, in certain embodiments, is quite likely to be performed, but may be optional if the first sequence of steps has already been successful. Therefore, the material removal process may already be sufficient with the first removal before the first control by the above-described control unit. Therefore, the control unit may be configured to perform at least one check based on the analysis result as to whether the material removal has already reached the target point or whether one or more further iterations should be performed.

[0020] Further exemplary embodiments of the apparatus, methods, computer-readable media, and program elements are described below.

[0021] In one embodiment, the control unit is configured to iteratively repeat the sequence in the coordination loop, in particular by handling the component carrier structure in the coordination loop. Thus, the control unit (which may have, for example, a processor) may perform or control the iteration or repetition of the above-mentioned sequence, including the described feedback loop, in a precisely definable and fully automated manner.

[0022] In one embodiment, the material removal unit is configured to remove material from the component carrier structure by grinding. Specifically, grinding may refer to an abrasive machining process in which a grinding wheel (or another abrasive body) may be used as a material removal or cutting tool. Each particle of abrasive acts as a fine, single-point cutting edge and may shear tiny pieces from the component carrier structure. However, in other embodiments, material removal from the component carrier structure may be achieved by methods other than grinding, for example by laser machining or any kind of cutting.

[0023] In one embodiment, the material removal unit is configured to remove material from the component carrier structure by one of the group consisting of cross-section grinding and surface grinding. With regard to cross-section grinding, a cross-section of the component carrier structure may be created, allowing analysis at a plane cutting the plate-like component carrier structure. Cross-section grinding is a destructive technique in which a portion of the component carrier structure is cut or ground to expose an internal plane of interest for analysis. The resulting cross-section may allow evaluation of the quality of drill holes, evaluation of via plating quality and thickness, or other test objects to be analyzed. An example of such other test objects may be making gaps in the material of the component carrier structure accessible, indicating the quality of the lamination process. With regard to surface grinding or surface grinding, such techniques may be used to provide a smooth finish on flat surfaces of the component carrier structure. Surface grinding may be described as an abrasive machining process in which a spinning wheel (or any other body) covered with coarse particles cuts off small pieces from a main surface of the component carrier structure, thereby accessing the main surfaces of the internal layers of the component carrier structure.

[0024] In one embodiment, the apparatus comprises a polishing unit configured to polish the exposed surface of the component carrier structure after material removal. Polishing can refer to a process of creating a smooth surface by scraping or chemical action on the surface, leaving a surface with reduced roughness. In contrast to grinding, polishing does not remove a significant amount of material from the surface of the component carrier structure, but rather simply flattens the surface, thereby increasing planarity. Polishing can use multiple stages, starting with a coarser abrasive, with each subsequent stage using a finer abrasive.

[0025] In one embodiment, the material removal unit is configured to remove material from the component carrier structure by a coarser grinding stage followed by a finer grinding stage. The coarse grinding may use a larger grain size than the fine grinding. Furthermore, more than two grinding stages are possible, for example using at least three different grain sizes, with the grain size decreasing with each grinding stage. By such a multi-stage grinding process, the surface of the component carrier structure undergoing material removal may be gradually processed without introducing artifacts due to the material removal process.

[0026] In a preferred embodiment, the progress measurement unit is configured to measure progress during removal of material by the material removal unit. Advantageously, material removal can be measured on-the-fly, i.e., while the material removal process is taking place. This accelerates sample preparation, allows particularly accurate monitoring and control of the material removal process, and strongly reduces the risk of excessive material removal. Additionally or alternatively, progress of the material removal process can also be measured after the material removal process or between two subsequent material removal stages.

[0027] In one embodiment, the progress measurement unit is configured to measure progress by optically detecting images of the component carrier structure. More specifically, an optical camera may capture images of the exposed surface of the component carrier structure during and / or after material removal as a basis for later determining one or more exposed test targets to be used for quality testing.

[0028] In one embodiment, the progress measurement unit is configured to measure progress by electrically measuring electrical signals in conductive structures of the component carrier structure during and / or after material removal. Specifically, the conductive structures may belong to test objects or sacrificial structures of the component carrier structure. During material removal, parts of the test objects and / or at least parts of the sacrificial structures may also be removed from the component carrier structure. By connecting the conductive test objects or the conductive sacrificial structures with one or more electrodes of the progress measurement unit, it may be possible to detect electrical signals of said conductive structures, which may characteristically change during the material removal process due to at least partial removal of the conductive structures. Specifically, it may be possible to detect an ohmic resistance of the conductive structures, which increases with continued removal of the conductive structures. Thus, the aforementioned electrical signals may be a fingerprint of the progress of the material removal process. Therefore, the progress measurement unit may be configured to measure progress by detecting electrical signals of the at least partially removed conductive structures during material removal to expose at least one test object, the conductive structures being configured to be used to detect the progress of material removal until the at least one test object is exposed according to a predetermined material removal objective.

[0029] In one embodiment, the progress measurement unit comprises a removed material quantification unit configured to quantify the amount of removed material. By collecting (e.g., with a weighing machine) small pieces of material removed (e.g., by grinding) from the component carrier structure, information about the progress of the material removal process can be obtained and the material removal process can be stopped when a desired test object or previously unseen plane of interest is exposed, preferably when the center of the drill hole is reached.

[0030] Additionally or alternatively, other concepts for determining the progress of the material removal process (specifically the grinding progress) may be implemented as well, such as detecting a changed position of the outer edge of the component carrier structure in terms of material removal, detecting a changed position of a material removal unit or tool affecting the component carrier structure to remove material therefrom, detecting sensor data (e.g. contact pressure and / or rotation speed) indicative of the impact of the material removal unit on the component carrier structure, detecting changes in sensor data sensed on a sacrificial structure and / or on a test object of the component carrier structure in terms of material removal, etc.

[0031] In one embodiment, the progress measurement unit is configured to measure progress based on a spatial progress of the material removal unit during removal of material of the component carrier structure. During removal of material from the component carrier structure by an abrasive process (such as grinding), the abrasive removal unit (e.g., a grinding device) may move forward to extend into and into the outer edge of the component carrier structure from which material is removed. Thus, the spatial displacement of the material removal unit may be used as a measure of the progress of the material removal process.

[0032] In one embodiment, the progress measurement unit is configured to measure progress based on detecting a contact pressure of the material removal unit on the component carrier structure (specifically, the time dependence of the contact pressure) during material removal of the component carrier structure. When an abrasive removal unit (such as a grinding device with a rotating grinding tool) is pressed against the surface of the component carrier structure from which material is to be removed, the contact pressure may provide information about the progress of the material removal process. For example, a pressure sensor, a strain sensor, etc. may be integrated into the material removal unit, preferably at or near its interface with the component carrier structure. For example, when material removal of the component carrier structure progresses from removing resin to removing copper (e.g., filled in drill holes), a discontinuous increase in the contact pressure may be detected. However, when material removal of the component carrier structure progresses from removing resin to removing unplated hollow drill holes, a discontinuous decrease in the contact pressure may be detected. If the structure of the component carrier structure (e.g., a predetermined coupon) is known, detecting the time dependence of the contact pressure in combination with the known structure of the component carrier structure may make it possible to derive information about the progress of the material removal process.

[0033] In one embodiment, the progress measurement unit is configured to measure progress based on detecting a rotational speed of a rotatable body of the material removal unit while removing material of the component carrier structure. For example, the rotational speed of a rotary grinding tool removing material from the component carrier structure may depend on the material of the component carrier structure currently being removed. Thus, changes in the rotational speed of the material removal unit (which may be detected by a corresponding sensor) may provide information about the progress of the material removal unit into the heterogeneous material of the component carrier structure. Thus, if the structure of the component carrier structure (which may comprise resin and copper) is known, the time dependence of the determined rotational speed may indicate the current position and therefore the spatial progress of the material removal tool while removing material from the component carrier structure.

[0034] In one embodiment, the apparatus comprises an initial measurement unit configured to first measure the component carrier structure before material removal. The material removal unit may be configured to remove material of the component carrier structure based on the measurement results of the initial measurement unit. Once the position and / or orientation and / or contour of the component carrier structure have been measured, a subsequent material removal process may be adjusted or adapted to such measurement results. In particular, it may be possible to first measure deviations of the component carrier structure from, for example, a rectangular target shape and adjust the material removal process accordingly. For example, it may be possible that the leading edge of the component carrier structure undergoing material removal is slightly inclined with respect to the direction of travel of the material removal unit. Such spatial artifacts may be taken into account, corrected, or compensated for by the material removal process.

[0035] In one embodiment, the apparatus specifically comprises an alignment unit configured to align the component carrier structure prior to material removal based on detection of at least one alignment structure or feature on the component carrier structure. Preferably, said alignment unit may comprise a multi-axis robot, most preferably a hexapod, to obtain good alignment accuracy. To ensure proper orientation of the component carrier structure, the apparatus may automatically determine the position of one or more alignment markers on the component carrier and adjust the position and / or orientation of the component carrier structure before continuing processing. This improves the accuracy of the quality test.

[0036] In one embodiment, the apparatus comprises a detection unit configured to detect image data of the interior of the component carrier structure after said material removal. In this context, a previous interior plane of the component carrier structure that is imaged by the detection unit (e.g., with a camera) may be exposed by a previous material removal step. The result of the image detection may then be sent to a determination unit to determine the test object.

[0037] In one embodiment, the apparatus comprises a determination unit configured to determine at least one test object of the component carrier structure, and an evaluation unit configured to evaluate properties of the determined at least one test object of the component carrier structure to evaluate its quality. Also, one or more test objects may be determined from the polished component carrier structure in a fully automated manner. The evaluation unit may then evaluate a result of this determination to derive a quality test result.

[0038] In one embodiment, the apparatus comprises a monitoring unit, in particular an X-ray device, configured to monitor, in particular continuously monitor, the component carrier structure at least during at least a part of the aforementioned sequence. Such an X-ray device may also provide an image of the interior of the component carrier structure, e.g., showing the position of the test object therein before material removal. By using this information about the internal structure of the component carrier structure, the material removal process may be performed more accurately.

[0039] In one embodiment, the material removal objective is to reach the center of a test object (specifically, a drill hole or a conductive structure such as a pad or line) of the component carrier structure. The drill hole may have a cylindrical cross section (e.g., if formed by mechanical drilling) or a conical or frusto-conical cross section (e.g., if formed by laser drilling) in a cross-sectional plane perpendicular to the main surface of the plate-like component carrier structure. Such a drill hole may therefore have a central axis. To test the quality of such a drill hole type test object, it may be advantageous to expose the maximum area of the drill hole in a cross-sectional plane perpendicular to the main surface of the plate-like component carrier structure. Such a configuration may therefore be defined as the material removal objective to be achieved.

[0040] In one embodiment, the apparatus includes a mechanical stop configured to abut against the material removal unit to prevent excessive material removal of the component carrier structure by the material removal unit. For example, such a mechanical stop may be embodied as one or more robust mechanical stops. As the material removal unit advances toward the component carrier structure, the material removal unit may be automatically stopped at the position of the mechanical stop, thereby making excessive material removal impossible. Advantageously, the mechanical stop may be positioned such that when the material removal unit abuts against the mechanical stop, thereby preventing further advancement into the component carrier structure, the material removal unit advances only to a position corresponding to a predetermined material removal objective. To ensure that the mechanical stop is mechanically stronger than the material removal unit, its front surface may be hardened, for example, made of a diamond material.

[0041] In one embodiment, the device is configured to perform the described steps without human intervention. Correspondingly, the method may comprise performing the described steps without human intervention. Highly advantageously, none of the steps mentioned regarding coupon and allocated component carrier validity assessment require user intervention. This not only reduces the human resource effort for quality testing of component carrier structures, but also makes the quality testing more objective and therefore more meaningful and faster.

[0042] In one embodiment, the component carrier structure comprises a stack of at least one electrically insulating layer structure and at least one electrically conducting layer structure. For example, the component carrier may in particular be a stack of the above-mentioned electrically insulating layer structure and the above-mentioned electrically conducting layer structure formed by applying mechanical pressure and / or thermal energy. The above-mentioned stack may provide a plate-like component carrier that can provide a large mounting surface for further components and is nevertheless very thin and compact.

[0043] In one embodiment, the component carrier structure is formed as a plate. This contributes to a compact design, while the component carrier nevertheless provides a large base for mounting components thereon. Furthermore, specifically, naked dies as examples of embedded electronic components can be conveniently embedded in thin plates, such as printed circuit boards, due to their small thickness.

[0044] In one embodiment, the component carrier structure is configured as one of the group consisting of a printed circuit board, a substrate (specifically an IC substrate), and an interposer.

[0045] In the context of this application, the term "printed circuit board" (PCB) may specifically refer to a plate-shaped component carrier formed by laminating several conductive layer structures with several electrically insulating layer structures, for example, by applying pressure and / or supplying thermal energy. As a preferred material for PCB technology, the conductive layer structures are made of copper, while the electrically insulating layer structures may comprise resin and / or glass fiber, so-called prepreg or FR4 material. Various conductive layer structures can 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 filling them with a conductive material (e.g., copper), thereby forming vias or other through-hole connections. (For example, partially) filled holes can connect the entire stack (through-hole connections extending through several layers or the entire stack), or filled holes can connect at least two conductive layers, called vias. Similarly, optical interconnections can be formed through individual layers of the stack to accommodate electro-optical circuit boards (EOCBs). Aside from one or more components that may be embedded in the board, printed circuit boards are typically configured to house one or more components on one or both of the opposing faces of the board, which may be connected to each major surface by soldering. The dielectric portion of the PCB may be composed of a resin containing reinforcing fibers (such as glass fibers) or other reinforcing particles (such as reinforcing spheres, specifically glass spheres).

[0046] In the context of this application, the term "substrate" may specifically refer to a small component carrier. In relation to a PCB, a substrate may be a relatively small component carrier on which one or more components can be mounted and which can serve as a connection medium between one or more sub-chips and another PCB. For example, a substrate may have substantially the same size as the components (specifically, electronic components) mounted thereon (e.g., in the case of a chip scale 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 significantly higher density of horizontally and / or vertically arranged connections. Horizontal connections may be, for example, conductive paths, while vertical connections may be, for example, drilled holes. These horizontal and / or vertical connections are located within the substrate and may be used to provide electrical, thermal, and / or mechanical connections between, specifically, housed or unhoused components (e.g., bare dies) of an IC chip and a printed circuit board or intermediate printed circuit board. Thus, the term “substrate” also includes “IC substrate.” The dielectric portion of the substrate may be composed of a resin containing reinforcing particles (such as reinforcing spheres, specifically glass spheres).

[0047] The substrate or interposer may have or consist of at least a layer of glass, silicon (Si), and / or a photoimageable or dry-etchable organic material such as an epoxy-based build-up material (such as an epoxy-based build-up film), or a polymeric compound such as polyimide or polybenzoxazole (which may or may not contain photo- and / or thermo-sensitive molecules).

[0048] In one embodiment, the at least one electrical insulation layer structure comprises at least one resin or polymer, such as epoxy resin, cyanate ester resin, benzocyclobutene resin, bismaleimide-triazine resin, polyphenylene derivative (e.g., based on polyphenyl ether PPE), polyimide (PI), polyamide (PA), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), and / or combinations thereof. Reinforcing structures, such as webs, fibers, spheres, or other types of filler particles, made of glass (multilayer glass), can also be used to form composites. Semi-cured resins combined with reinforcing agents, such as fibers impregnated with the aforementioned resins, are called prepregs. These prepregs are often named after their properties, such as FR4 or FR5, to describe their flame retardancy. While prepregs, especially FR4, are typically preferred for rigid PCBs, other materials, such as epoxy-based build-up materials (e.g., build-up films) or photoimageable dielectric materials, can also be used. For high frequency applications, high frequency materials such as polytetrafluoroethylene, liquid crystal polymers, and / or cyanate ester resins may be preferred. In addition to these polymers, low temperature cofired ceramics (LTCC) or other low, ultra-low, or extremely low DK materials ("DK" can refer to the real part of the dielectric constant) may be applied to the component carrier as an electrically insulating structure.

[0049] In one embodiment, the at least one conductive layer structure comprises at least one of the group consisting of copper, aluminum, nickel, silver, gold, palladium, and tungsten. Copper is typically preferred, but other materials or coated versions thereof are also possible, particularly versions coated with superconducting materials such as graphene.

[0050] At least one component that can be embedded in the stack can be selected from the group consisting of a non-conductive inlay, a conductive inlay (such as a metal inlay, preferably containing copper or aluminum), a heat transfer unit (e.g., a heat pipe), a light-guiding element (e.g., an optical waveguide or optical conductor connection), an electronic component, or a combination thereof. The inlay can be, for example, a metal block with or without an insulating material coating (IMS-inlay) and can be embedded or surface-mounted to facilitate heat dissipation. Suitable materials are defined according to their thermal conductivity, which should be at least 2 W / mK. Such materials are often based on metals, metal oxides, and / or ceramics, such as, but not limited to, copper, aluminum oxide (Al2O3), or aluminum nitride (AlN). Other shapes with increased surface area are often used to increase the heat exchange capacity. Further, components may be active electronic components (implementing at least one pn junction), passive electronic components such as resistors, inductances, or capacitors, electronic chips, storage devices (e.g., DRAM or another data memory), filters, integrated circuits (such as Field-Programmable Gate Arrays (FPGAs), Programmable Array Logic (PALs), Generic Array Logic (GALs), Complex Programmable Logic Devices (CPLDs)), signal processing components, power management components (such as Field-Effect Transistors (FETs), Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs), Complementary Metal-Oxide-Semiconductors (CMOSs), Junction Field-Effect Transistors (JFETs), etc.), and the like.The component carrier may be a JFET (J-FET) or an insulated-gate field-effect transistor (IGFET), all based on semiconductor materials such as silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide (GaO), indium gallium arsenide (InGaAs), and / or any other suitable inorganic compound, optoelectronic interface elements, light-emitting diodes, photocouplers, voltage converters (e.g., DC / DC converters or AC / DC converters), cryptographic components, transmitters and / or receivers, electromechanical transducers, sensors, actuators, microelectromechanical systems (MEMS), microprocessors, capacitors, resistors, inductances, batteries, switches, cameras, antennas, logic chips, and energy harvesting units. However, other components may be embedded in the component carrier, such as magnetic element components. Such magnetic elements may be permanent magnetic elements (ferromagnetic, antiferromagnetic, multiferroic, or ferrimagnetic elements, such as, for example, ferrite cores) or may be paramagnetic elements. However, the components may also be IC substrates, interposers, or further component carriers, for example, in a board-in-board configuration. The components may be surface-mounted on and / or embedded within the component carrier. Furthermore, other components may also be used as components, in particular those that generate and emit electromagnetic radiation and / or that are sensitive to electromagnetic radiation propagating from the environment.

[0051] In one embodiment, the component carrier is a laminated component carrier, in such an embodiment, the component carrier is a composite of multiple layers that are stacked and interconnected by the application of pressure and / or heat.

[0052] After processing the internal layer structure of the component carrier, one or both opposing main surfaces of the processed layer structure can be covered symmetrically or asymmetrically (in particular by lamination) with one or more further electrically insulating and / or conductive layer structures, in other words, the lamination can be continued until the desired number of layers is obtained.

[0053] After the formation of the stack of electrically insulating and conductive layer structures has been completed, it is possible to proceed with a surface treatment of the resulting layer structure or component carrier.

[0054] Specifically, an electrically insulating solder resist can be applied to one or both opposing major surfaces of the layer stack or component carrier for surface treatment. For example, it is possible to form a solder resist or the like over the entire major surface, and then pattern the layer of solder resist to expose one or more conductive surface portions that will be used to electrically couple the component carrier to electronic peripherals. Surface portions of the component carrier that remain covered with the solder resist, particularly those containing copper, can be effectively protected from oxidation or corrosion.

[0055] Regarding surface treatment, it is also possible to selectively apply a surface finish to exposed conductive surface portions of the component carrier. Such a surface finish can be a conductive covering material on exposed conductive layer structures (especially copper-containing or copper-made structures, such as pads, conductive tracks, etc.) on the surface of the component carrier. If such exposed conductive layer structures are left unprotected, the exposed conductive component carrier material (especially copper) can oxidize, reducing the reliability of the component carrier. The surface finish can then be formed, for example, as an interface between a surface-mounted component and the component carrier. The surface finish has the function of protecting the exposed conductive layer structures (especially copper circuits) and enabling a joining process with one or more components, for example, by soldering. Examples of suitable materials for the surface finish are Organic Solderability Preservative (OSP), Electroless Nickel Immersion Gold (ENIG), gold (especially hard gold), chemical tin, nickel gold, nickel palladium, Electroless Nickel Immersion Palladium Immersion Gold (ENIPIG), and the like.

[0056] The above-defined and further aspects of the invention are apparent from and will be elucidated with reference to the example embodiments described hereinafter. [Brief explanation of the drawings]

[0057] [Figure 1] 3 shows a flowchart of a method for performing a quality test of a component carrier structure according to an exemplary embodiment of the present invention.

[0058] [Figure 2] 1 illustrates schematically an apparatus for performing a quality test of a component carrier structure according to an exemplary embodiment of the present invention;

[0059] [Figure 3] 1 shows details of an apparatus for performing quality testing of a component carrier structure according to an exemplary embodiment of the present invention;

[0060] [Figure 4] 1 illustrates an apparatus for processing a component carrier structure for quality testing according to an exemplary embodiment of the present invention.

[0061] [Figure 5] As an example of a component carrier structure, a coupon having a sacrificial structure used to control the progress of a material removal process is shown in accordance with an exemplary embodiment of the present invention.

[0062] [Figure 6] 1 shows a block diagram of a method for processing a component carrier structure for quality testing according to an exemplary embodiment of the present invention;

[0063] [Figure 7] 1 illustrates a component carrier structure having a test object prior to a material removal process and being monitored initially and / or continuously to adjust the material removal process, according to an exemplary embodiment of the present invention.

[0064] [Figure 8] 1 illustrates a component carrier structure having a test object undergoing a material removal process by a material removal unit according to an exemplary embodiment of the present invention, where the advancement of the material removal unit and / or the amount of removed material can be monitored for progress control.

[0065] [Figure 9] 1 illustrates a component carrier structure having a test object and a sacrificial structure undergoing a material removal process by a material removal unit according to an exemplary embodiment of the present invention, where electrical signals can be detected in the sacrificial structure and / or the test object for progress control.

[0066] [Figure 10]1 illustrates a component carrier structure having mechanical stops to prevent excessive material removal relative to the test object and progress control, according to an exemplary embodiment of the present invention.

[0067] The figures in the drawings are schematic representations, and in different drawings, similar or identical elements are provided with the same reference signs.

[0068] Before referring to the drawings, exemplary embodiments will be described in more detail and some basic considerations will be summarized based on which exemplary embodiments of the present invention have been developed. DETAILED DESCRIPTION OF THE INVENTION

[0069] According to an exemplary embodiment of the present invention, an apparatus and method are provided for processing a component carrier structure (such as a coupon, a PCB or preform thereof, a panel, etc.), from which material may be removed (e.g., by grinding, milling, chipping, machining, cutting, etc.). The progress of the material removal process may be measured. Then, based on the results of the measurements, it may be analyzed whether a predetermined purpose, goal, or objective of the material removal process has been achieved (e.g., whether a previous internal cross-sectional plane of interest of the component carrier structure has been exposed and shows test objects (e.g., drill holes) in a desired field of view). In this case, an image of the now-exposed cross-sectional plane may be detected (preferably after polishing), in which one or more test objects are visible in a desired manner, and the one or more test objects may be determined and evaluated to derive attributes or characteristics of the component carrier structure under analysis. If the aforementioned objective has not yet been achieved, the process of material removal by grinding the component carrier, measuring the grinding progress and / or results, and evaluating whether the grinding objective has been achieved may be repeated iteratively two or more additional times until the grinding objective is achieved. Thus, an adjustment feedback loop may be implemented that continues grinding until a predetermined grinding success is achieved for the exposure of the test object. Such an automated process may advantageously overcome traditional limitations on throughput of manual grinding, while also overcoming traditional limitations on the limited accuracy of automated grinding processes.

[0070] According to an exemplary embodiment of the present invention, a control system is provided that allows for precise alignment and progress monitoring during the grinding and polishing process. This may allow for precise alignment of the specimen and the grinding / polishing device. Furthermore, this may allow for progress monitoring during the grinding and polishing process. Specifically, a closed control loop (preferably implementing online measurement of grinding progress) may be implemented for alignment and progress control.

[0071] More specifically, such a control system for the grinding and polishing process may enable precise alignment of the sample and the grinding / polishing device via a microscope / camera combination. Furthermore, progress during a single grinding and polishing run may be monitored. More specifically, sample alignment, grinding / polishing progress, and continuous monitoring of grinding / polishing quality may be continuously monitored by optical, electrical, X-ray, mechanical, and / or chemical features and methods that may be incorporated into the sample. Highly advantageously, a closed control loop (including online measurements) may be introduced for alignment and progress (specifically, sensors may be implemented not only in the control system but also in the sample). Furthermore, a fully automated quality testing device may be provided that implements the above and / or other features. By taking the above-mentioned measures, it may be possible to obtain a fully automated object preparation system, preferably with high accuracy and throughput.

[0072] Therefore, advantageous features of an apparatus for processing component carriers for quality testing, in particular of its control system, may be one or more of the following: - An automated grinding (and preferably polishing) process is provided, for example supported by camera-based and / or microscope-based control. The grinding process described above may be equipped with a camera control system. The automated grinding (and preferably polishing) process may be carried out using a properly aligned component carrier structure, in particular using one or more alignment marks on and / or in the component carrier structure. The grinding process can be carried out using monitoring of the grinding thickness, or more generally, measuring the progress of material removal. The grinding progress can be measured by observing the degree of grinding (explainingly, a grinding guide can therefore be provided). More specifically, a fully automated grinding process can be carried out using the grinding guide or control track described above. It may also be possible to use one or more PCB features in the analysis and use them as references for alignment. In particular, a feedback control loop may be advantageously provided so that the image of the actual position does not form the sole basis for control.

[0073] Advantageously, exemplary embodiments of the present invention may provide a control system with separate control stations for the entire system. Each cross-sectional image may be used for purposes such as coupon alignment, grinding progress, cross-sectional image quality, etc. Optionally, cleaning and / or polishing quality may also be detected by the apparatus according to exemplary embodiments of the present invention. Proper alignment between the component carrier structure and the apparatus may be ensured by using a microscope (which may detect alignment markers on the component carrier structure). Additionally, exemplary embodiments may perform X-ray and / or electrical measurements (e.g., to characterize buried vias).

[0074] Thus, exemplary embodiments may automate the preparation process of preparing a component carrier structure for quality testing. Specifically, an advantageous control loop may identify, align, prepare, and control the component carrier structure for a device under test (DUT). This control loop may be maintained until a desired result is achieved.

[0075] Processes according to exemplary embodiments of the present invention are described in further detail below. Regarding material removal to expose test targets on the component carrier structure, the component carrier structure may first undergo a coarse grinding process, followed by a fine grinding process. During coarse grinding (e.g., at least 200 μm), the grain size may be larger than during fine grinding (e.g., 100 μm or less). While a significant amount of material is removed from the component carrier structure during grinding, subsequent polishing may substantially planarize the surface even with small grain sizes (e.g., 20 μm or less) without significant material removal. Illustratively, polishing may reduce surface roughness without substantial material removal. For example, grinding may be a wet grinding process assisted by rinsing the grinding body with water while rotating. During polishing, an emulsion containing diamond particles or the like may be used.

[0076] Regarding the alignment of a component carrier structure relative to an automated device, particularly its material removal unit, a robot (such as a multi-axis robot) or any other suitable entity of a handling unit can grasp a component carrier structure (e.g., a coupon), align the component carrier structure (e.g., after detecting one or more alignment structures on the component carrier structure), measure the spatial distance relative to the component carrier structure, and then control the material removal unit to approach the component carrier structure for material removal. For this purpose, for example, a first optical measurement can be performed before material removal and a second optical measurement can be performed after material removal. Before the optical measurement, the imaged surface of the component carrier structure can be cleaned. If the second optical measurement indicates that the material removal objective has not yet been achieved (particularly because a test object, such as a drill hole, has not yet been exposed or has not yet been exposed to the desired extent), one or more further iterations of material removal can be performed. These iterations can be repeated until the material removal objective is achieved, for example, until a measured parameter of the test object (particularly the diameter of the drill hole) reaches a predetermined target value (e.g., a drill hole diameter of 50 μm). For example, a respective optical measurement can be performed between each two subsequent material iterations. Preferably, the progress of the material removal process can be measured during and / or after each iteration. For example, this can be achieved by electrical measurement of the conductive structures of the component carrier structure during grinding; when the conductive structures are partially (and optionally eventually completely) removed during the material removal process, the electrical detection signal can become weaker (and optionally eventually disappear). Additionally or alternatively, it is also possible to measure the progress of the position of the grinding device so that the grinding process can be terminated when the final position of the grinding device (and corresponding target configuration of the component carrier structure) is reached. Also, X-ray analysis can be performed during the continuous monitoring of the grinding process. Also, the planarity of the cross-sectional plane can be monitored. Preferably, polishing is started only when the monitoring of the previous grinding process is completed. The described process can be performed for cross-sectional grinding or surface grinding.

[0077] In one embodiment, a method for testing the quality of a component carrier structure may comprise the following steps: a handling unit (such as a robot) grips a component carrier structure (such as a coupon); the component carrier structure is aligned and positioned; material of the component carrier structure is then removed in one or more stages, in particular a grinding stage; the surface of the component carrier structure exposed by the material removal may then optionally be cleaned; measurements (e.g. optical and / or electrical) may be performed to assess whether the progress of the material removal process has achieved a predetermined material removal objective; if this is not yet the case, the sequence of material removal and progress measurements and analysis may be repeated any desired number of times until the material removal objective is achieved; then, for quality testing, the exposed surface with the test object in its desired configuration may be polished, and optical measurements may be performed as a basis for subsequent defect analysis on the exposed test object; thus, determination of said test object and evaluation of its properties may then be performed; the quality test may then be completed. For example, to assess defects, one or more of the criteria set out in chapter "3.6 Structural Integrity" of IPC-6012D (version: September 2015) may be considered.

[0078] Examples of variables that affect the cross-sectioning of the component carrier structure (see more detailed discussion of individual variables below) are the grinding body used for material removal, alignment (e.g., use of a handling arm), pressure applied during grinding and / or polishing, rotational speed during grinding and / or polishing, specifically control of material removal from the component carrier structure (more specifically, control of the progress of material removal), cleaning (of the component carrier structure and / or grinding body) to avoid carryover, heating or cooling, and thermal and mechanical loads.

[0079] For grinding, adjustable parameters are particle size, contact pressure, and rotation speed of the grinding medium. The particles can also be adjusted for the grinding machine. Polishing of the cross-sectional surfaces of the component carrier structure can be carried out using a diamond suspension (rotation can be synchronous or counter-rotating). Optionally, immersion and / or filling of the component carrier structure can be possible to prevent contamination of the copper holes.

[0080] With regard to the abrasive body used for material removal, it may be advantageous for the material removal process not to generate excessively high temperatures in order to keep the laminate of the component carrier structure intact. Preferably, the material removal process may be carried out at a temperature significantly below the glass transition temperature Tg of the resin material of the component carrier material (e.g., at least 10% below Tg on the Celsius or Kelvin scale). For example, water may be used as a cooling and / or washing medium.

[0081] Grinding may be preferred to remove material from the component carrier structure, however material removal may also be achieved by (e.g., wire) cutting, wire erosion, plasma treatment, laser treatment, sandblasting, water jet, milling, sawing, treatment with gate shears, ion beam treatment and / or punching.

[0082] Preferably, the particle size can be fine enough to assist subsequent polishing (especially at the end of material removal). The particle size can be selected depending on the polishing suspension used. For example, 3 μm particles may only be applicable to a certain degree of grinding.

[0083] To limit variations in the planarity of the ground and / or polished surface of the component carrier structure, it may be advantageous to avoid excessively high and low temperatures. Furthermore, thermal and mechanical loads should be kept low.

[0084] When designing the handling arm of the handling unit, the slip and / or rotation of the component carrier structure should be kept as low as possible. This favorable boundary condition can influence the selection of the maximum rotation speed.

[0085] Next, embodiments of the grinding process will be described. Advantageously, an iterative grinding control process can be implemented. The grinding discs (or plates) can be positioned horizontally or vertically, or at a special angle if necessary or desired (taking into account the type of grinding to be performed).

[0086] Regarding the control of the progress of material removal, a camera can be used to monitor the grinding progress. For example, such a camera can be placed on and / or in the grinding body. This can facilitate the planarity and / or alignment of the processed surface of the component carrier structure. Progression control can also be achieved by electrical measurements, for example, by contacting the copper structure being partially or completely removed at a specific material removal progress state, which can be detected by a change in an electrical signal. Additionally or alternatively, progress control can be based on one or more mechanical stops (e.g., having a sufficiently hard surface, preferably a diamond surface) that the grinding body abuts when a predetermined progress of the material removal process is achieved. Resistance measurements against the grinding body can also be used for progress control. In other embodiments, incremental feed can be measured for progress control. For example, with reference to through-holes, a significant pressure drop can occur the moment such holes open. When a microvia is reached, the effect on pressure can be reversed, i.e., an increase in pressure or an increase in resistance can be detected. Grinding metallic via material rather than softer plastic material can result in higher pressure. An electrical signal may be measured in the microvia, and as the conductive material in the microvia is removed, electrical resistance may increase, which may also be detectable. Yet another embodiment of progress control may detect, for example, a change in color of the water when the target is reached. Resistance measurements (e.g., of the sacrificial structure removed during grinding) may also be used for progress control. Yet another embodiment of progress control may use sound detection, tribometer-based detection, a pin pressing against the grinding disk (optionally combined with a light barrier), etc. Grinding may stop once the center of the drill hole is detected.

[0087] Preferably, the progress can be measured at or near the test object. Furthermore, with reference to the progress control of the grinding process, sudden stops may be possible. However, iterative grinding processes are also possible.

[0088] In one embodiment, the contact pressure between the grinding body and the component carrier structure may be measured. For example, this may be achieved in an automated manner by a pressure regulator (e.g., adjusting according to force). The pressure may remain constant or may be varied during material removal. With fewer grinding bodies, a balance between time, pressure, and rotation may be maintained. It may also be possible to apply a variable pressure depending on throughput, quality targets, and sample thickness. The maximum pressure may be adjusted to avoid damage to the component carrier structure, especially at or around test targets such as drill holes. In particular, the contact pressure may be selected depending on how the component carrier is to be ground (e.g., grinding along a layer, grinding against a layer, etc.). It should be noted that the cutting preparation neither increases nor decreases quality issues in the component carrier structure.

[0089] Regarding rotation speed and type, it may be advantageous to generate heat only below a predetermined maximum. The direction of rotation may be synchronous or counter. Gripping or handling devices (such as clamping devices, handling fixtures, hexapods, etc.) may be rapidly vibrated.

[0090] Adjustable rotation parameters include rotation time, contact pressure, type of rotation, material of the component carrier structure, particles, etc.

[0091] Regarding the alignment or orientation of the component carrier structure during processing to perform quality testing in an automated manner, the camera can determine whether the component carrier structure sample is correctly positioned before the first grinding. If necessary, the position of the component carrier structure can be corrected to ensure proper alignment (e.g., based on comparison with external reference holes, which are preferably not copper-plated; such reference holes can be drilled or etched, for example, in a photo process). Alternatively, a mechanical alignment step (e.g., using alignment pins) can be performed.

[0092] The goal of alignment may be to orient the target plane and grinding media parallel, which may be achieved by correspondingly influencing the media, grinding bodies, rotating one or even all of the components involved, etc.

[0093] Further referring to alignment, the camera image may capture the reference point and the target point displayed. Such data may define (software-supported, mechanically, etc.) the target plane and make it parallel to the grinding media. In further alignment control, the limiting factor may be the combination of hexapod / grinding speed / maximum force to maintain alignment corresponding to the mechanical stability of the entire system.

[0094] Referring now to cleaning of the component carrier structure, one embodiment may clean the component carrier structure during grinding. In an iterative approach, there may be a cleaning step before each new grinding step (e.g., coarse grinding followed by fine grinding). Cleaning may ensure that no particle carryover occurs. For example, particles may be blown off, sucked up, evaporated, burned off, scraped off, brushed, rinsed, etc. for cleaning. For example, continuous cleaning may be performed during the grinding process. Suction, rinsing (preferably in a bath or sink), scraping, blowing off, ultrasonic bath (shake-off), or other cleaning units may be performed. Advantageously, very small scratches may be rinsed away by cleaning. After cleaning, it may be advantageous for the remaining particles to be at most the same size as or smaller than the particle size used in the next grinding step.

[0095] Regarding the coupon design, it can be standardized or can deviate from the standard. Any deviations can be coordinated with the user. For example, a coupon-type component carrier structure can be provided with one or more alignment holes, wear sensors, etc.

[0096] Examples of quality criteria or characteristics for quality assessment of a component carrier structure are sharp edges (preferably 90°), a radius close to zero, flatness, tolerance below a pre-defined threshold (e.g., 10% or preferably less than 10%, with a tolerance of 7% or less). A further quality feature of the component carrier structure is that it should be free of scratches in images at 100x magnification. Furthermore, the component carrier structure should be free of gaps (specifically between the sample and the embedding medium, more specifically between the conductive layer and the embedding medium, and especially between the copper and the embedding medium). Although the resin may shrink during embedding (fast-setting embedding mediums lose a lot of volume, while slow-setting embedding mediums lose very little), the shrinkage should not be excessive.

[0097] Figure 1 shows a flowchart 170 of a method for performing quality testing of a component carrier structure 102, according to an exemplary embodiment of the present invention. Reference numbers used in the description of Figure 1 refer to the embodiments of Figure 2 or Figure 3. Preferably, the component carrier structure 102 described above is a coupon forming part of a panel and can be used to test component carriers (such as printed circuit boards (PCBs) or integrated circuit (IC) boards). However, the component carrier structure 102 can alternatively be a panel or array (such as a quarter panel) having multiple connected preforms of component carriers, or preforms of component carriers or easily manufactured component carriers.

[0098] Advantageously, the method of flowchart 170 may correspond to the performance of a quality test of a component carrier structure 102 by an automated apparatus 100. Preferably, the method may comprise performing the quality test without human intervention between the inlet 106 (logically corresponding to input 172) and the outlet 108 (logically corresponding to output 190) of said apparatus 100. In other words, the inlet 106 of apparatus 100 corresponds to the input 172 of the method, while the outlet 108 of apparatus 100 corresponds to the output 190 of the method. More specifically, an automated process is provided for the preparation and visual inspection of cross sections and for measuring the component carrier structure 102. Preferably, no manual work occurs and the entire process may be automated. To this end, test coupon-type component carrier structures 102 may be configured for automated handling and machine-readable serialization.

[0099] As indicated by reference numeral 172 , the component carrier structure 102 may be included in the apparatus 100 .

[0100] Referring to block 174, a coupon may be inserted into the apparatus 100 as a component carrier structure 102, which may then be handled fully automatically by the robot 120. More specifically, the coupon may be a component carrier structure 102 that may be constructed or designed in accordance with IPC-2221, for example. The component carrier structure 102 may provide traceability information to the apparatus 100. To this end, a method that may be performed using the apparatus 100 may comprise automatically identifying component carrier structures 102 that are to undergo quality testing. For example, it may be possible to register coupon-type component carrier structures 102 in a list. Multiple coupons may be sorted. For traceability purposes, it may be possible to assign information such as lot number, panel number, array number, x / y information, cross section number, report number, request identifier, etc. to a data set assigned to each component carrier structure 102. For example, such a data set may be stored in the database 128.

[0101] Referring to block 176, the component carrier structures 102, which may still be integrally connected with the rest of the panel, etc., may be singulated or separated, for example by milling or cutting the component carrier structures 102 from the larger body 160, such as a panel. For this purpose, it may be possible to locate a defined position of the component carrier structure 102 within the larger body 160 and cut it out. As a result, a test specimen in the form of a separated component carrier structure 102 may be obtained. For example, the cutting out of the component carrier structure 102 may be achieved according to a minimum plated-through hole or in response to a user definition.

[0102] Referring to block 178, the component carrier structure 102 may then be subjected to thermal stress, for example by performing a solder float test. For example, the component carrier structure 102 may be immersed in molten solder to subject the component carrier structure 102 to thermal stress. As an alternative to a solder float test, it may also be possible to perform alternative thermal stress methods, for example a reflow simulation.

[0103] Referring to block 180, the component carrier structure 102 may or may not undergo an encapsulation process to simplify handling and / or buffer stress during subsequent quality testing. While traditional manual quality testing of component carrier structures may require encapsulation before assessing quality, such embedding may be omitted in accordance with exemplary embodiments of the present invention including fully automated quality testing of the component carrier structure 102. If optionally performed, the encapsulation process may place the component carrier structure 102 in an embedding material, such as resin, for further preparation. However, since automated handling in accordance with exemplary embodiments of the present invention may be achieved without such encapsulation, in other embodiments such embedding may be advantageously skipped (as indicated by reference numeral 192).

[0104] Referring to block 182, it may then be possible to remove material of the component carrier structure 102 in order to expose the interior of the component carrier structure 102, which will be subjected to a quality test. More particularly, a specimen (particularly a cross-section) of the component carrier structure 102 may be prepared. For this purpose, the component carrier structure 102 may be ground and subsequently polished to a defined position (preferably to the center of a via or drill hole or pattern). For example, different stages of abrasive paper treatment and polishing may be performed. For grinding, it may be possible to use, for example, abrasive paper with different grains (for example using one or more of the following grains: 60, 180, 1200, 2000).

[0105] Referring to block 184, the method may then comprise determining one or more predetermined test targets 116 (such as plated vias and their properties) of the component carrier structure 102 after said material removal. Furthermore, the method may comprise evaluating properties or attributes of the one or more test targets 116 of the component carrier structure 102 to assess the quality of the component carrier structure 102. When skipping block 180, the method may comprise determining at least one predetermined test target 116 based on the unencapsulated component carrier structure 102 or, alternatively, based on the encapsulated component carrier structure 102. In particular, a visual analysis of a cross-section of the component carrier structure 102 may be performed, preferably in an automated manner. For example, x / y dimensional measurements may be performed (e.g., inspecting build-up, copper thickness, etc.). In particular, the visual inspection may include an analysis of specific defects. During the inspection, one or more of the following test targets 116 and assigned properties may be considered: The quality of the multilayer build-up; plated-through hole characteristics (such as wall characteristics and land characteristics); and surface roughness (for example, the surface roughness can be determined according to the Ra scale and / or the Rz scale). Regarding roughness, the roughness value Rz can be used as a criterion for the presence of scratches on the exposed surface (particularly the cross section) of the component carrier structure 102, while the roughness value Ra can be used as a criterion for the quality of the material removal process (particularly the grinding process). For example, a quality criterion can be that the roughness of the surface of the component carrier structure 102 exposed by grinding and / or polishing must not be greater than the roughness of the grinding disk and / or polishing paste used in the previous material removal step. If this criterion is not met, it can be concluded that artifacts were introduced in an earlier material removal step. For example, a measurement resolution of at least 1 μm can be obtained. For example, quality tests according to IPC-6012, IPC-A-600, etc. can be performed.

[0106] Referring to block 186, the method may include generating and storing a report having predetermined characteristics. The report may summarize the quality test and its conclusions. This may ensure proper documentation of the quality test.

[0107] Referring to block 188, the method may then comprise archiving the analyzed component carrier structure 102 and the quality tests. In particular, this may include sample storage, electronic document storage, etc.

[0108] The component carrier structure 102 may then be output from the apparatus 100 as indicated by reference numeral 190 .

[0109] 2 shows a schematic diagram of an apparatus 100 for performing quality testing of a component carrier structure 102, here embodied as a coupon, according to an exemplary embodiment of the present invention. As indicated by the surrounding casing 131 of the apparatus 100, the entire quality test can be performed in an automated manner within a closed cell.

[0110] The upper left side of FIG. 2 shows a plan view of a planar sheet-like body 160, which may be a panel for manufacturing multiple component carriers (such as printed circuit boards) in a batch procedure. The illustrated panel may have dimensions of, for example, 18×24 square inches (45.72×60.96 square centimeters) or larger. The central main area of the panel may be subdivided into multiple arrays 161 (four quarter panels in the illustrated embodiment), each containing multiple PCBs. One or more strip-shaped test coupons may be formed as component carrier structures 102 in a frame 163 surrounding the component carrier. Advantageously, at least one horizontally extending component carrier structure 102 and at least one vertically extending component carrier structure 102 may be foreseen to enable quality tests to be performed that identify potential structural defects in two perpendicular directions.

[0111] Referring now in more detail to the apparatus 100, an inlet accommodating unit 136 is disposed at the inlet 106 of said apparatus 100 and is configured to accommodate a stack of component carrier structures 102 prior to testing. Thus, coupon-type component carrier structures 102 may be inserted into the inlet accommodating unit 136 after being separated from the panel-type body 160. Alternatively, larger bodies 160, each containing at least one component carrier structure 102, may be stacked within the magazine-type inlet accommodating unit 136.

[0112] The robot handling unit 104 is configured to handle the component carrier structure 102 (optionally still connected within the body 160) along various portions between the entrance 106 and the exit 108 of the apparatus 100. Specifically, the handling unit 104 is configured to grasp and transfer the component carrier structure 102 (or the entire body 160) to be tested from the entrance receiving unit 136 through the entrance 106 to the identification unit 110, described below. More specifically, the handling unit 104 has an entrance handling subunit 122 configured to handle the component carrier structure 102 between the entrance 106 and the material removal unit 112, described below. Advantageously, the handling unit 104 has one or more robots 120, which may include one or more hexapods, one or more linear robots, one or more articulated arm robots, etc. A six-axis robot or hexapod (schematically indicated by reference numeral 120 in FIG. 2) may be equipped with sensors and have axes suitable for handling the component carrier structure 102 in the fully automated apparatus 100. Advantageously, a hexapod may be used for the material removal processes (particularly grinding processes) performed by the material removal unit 112, so that the hexapod may be mechanically stable and simultaneously adapted very precisely in six axes. Referring to FIG. 3, a six-axis robot or hexapod may be used in the cross-section station 127 to operate the material removal unit 112 and / or to operate the alignment unit 154. As a result, the preparation of the component carrier structure 102 by material removal may be very precise and robust against possible misalignments. Additionally, linear robots and / or articulated arm robots (not shown) of the entry handling subunit 122 and / or the exit handling subunit 124 of the handling unit 104 may be used to handle the component carrier structures 102 between individual workstations of the automated apparatus 100.

[0113] As already mentioned, the inlet handling subunit 122 of the handling unit 104 delivers the component carrier structures 102 to the identification unit 110. The latter is configured to identify the component carrier structures 102 on which a quality test should be performed. This allows traceability to be guaranteed. More specifically, the identification unit 110 is configured to identify the component carrier structures 102 based on the detection of an identifier 126, which may be physically connected to the component carrier structure 102 or may form an integral part of the component carrier structure 102. For example, such an identifier 126 may be a QR code, a barcode, or an alphanumeric code that can be read by an optical reader of the identification unit 110. The identifier 126 may also be a transponder, such as an RFID (Radio Frequency Identification) tag or an NFC (Near Field Communication) tag. In such an embodiment, the identification unit 110 may comprise a wireless reader configured to wirelessly read the transponder-type identifier 126 to retrieve the identification information. The identification unit 110 may access a corresponding database 128 to identify the component carrier structure 102 based on its identifier 126 and / or to obtain additional data (e.g., specific quality test instructions) assigned to the identified component carrier structure 102. Specifically, the identification unit 110 may be configured to identify the component carrier structure 102 by matching the detected identifier 126 with correlated identification information stored in an assigned dataset in said database 128. For example, such dataset may correlate an identification code readable from the identifier 126 with further information about the component carrier structure 102, e.g., information about its manufacturing history (such as lot number, manufacturing date, manufacturing time, etc.). The identification unit 110 may also be configured to retrieve quality test-related information from the database 128, indicating quality tests to be performed on the identified component carrier structure 102. Such quality test-related information may define the quality tests to be performed on the identified component carrier structure 102.Different quality tests may be performed for different types of component carrier structures 102.

[0114] In embodiments in which the component carrier structures 102 have not yet been separated from the larger body 160 before they are introduced into the apparatus 100 through the entrance 106, a singulating unit 148 (such as a milling machine or laser cutter) may be provided and configured to singulate the component carrier structures 102 from the panel-type body 160. For example, singulation may be achieved by milling or laser cutting.

[0115] The processed component carrier structure 102 may then be transported by the handling unit 104 to a thermal stress exposure unit 150 configured to expose the component carrier structure 102 to thermal stress. Preferably, the thermal stress exposure unit 150 is configured to float the component carrier structure 102 on a thermal stress bath, which may contain molten solder, so that the component carrier structure 100 may be subjected to thermal stress.

[0116] The component carrier structure 102 may then be transferred to a material removal unit 112 by the robot mentioned above or by another robot 120 of the handling unit 104. The latter is configured to remove material of the component carrier structure 102 to expose the interior of the component carrier structure 102 that is undergoing or will undergo quality testing. In particular, the material removal unit 112 may be configured to remove material of the component carrier structure 102 by grinding, preferably by cross-grinding (or alternatively by surface grinding).

[0117] To improve the accuracy of the material removal, the component carrier structure 102 may be aligned by an alignment unit 154, which may be configured to determine alignment markers (e.g., drill holes) of the component carrier structure 102, for example, based on a captured image thereof. The alignment may be performed before grinding by the material removal unit 112. The alignment unit 154 may be assigned to the material removal unit 112 and configured to align the component carrier structure 102 before the material removal process. Thus, the alignment performed by the alignment unit 154 is preferably performed before the material removal process performed by the material removal unit 112. Thus, such alignment may form part of the material removal process, in particular the grinding process.

[0118] Optionally, a removed material quantification unit 142 may be provided and configured to quantify the amount of material removed from the component carrier structure 102 during grinding. Determining the amount of material removed may allow for precise control of the grinding progress and therefore the grinding process.

[0119] After grinding, the component carrier structure 102 may be fed to a polishing unit 140 configured to polish the exposed surface of the component carrier structure 102 after removing material. Rather than removing a significant amount of additional material from the component carrier structure 102 (as occurs during grinding), polishing may reduce surface roughness and improve surface quality without excessive material removal. The polished surface may provide more accurate information about one or more test objects 116, which are used as features of interest to be analyzed below.

[0120] Only optionally, the component carrier structure 100 may then (or alternatively already before material removal by the material removal unit 112) be fed to an encapsulation unit 144 configured to encapsulate the component carrier structure 102 in an encapsulant 146 such that the component carrier structure 102 remains detectable within the encapsulant 146. Such an encapsulant 146 may be a resin that acts as a stress buffer and simplifies handling of the component carrier structure 102 during subsequent (and / or previous) analysis.

[0121] However, it may alternatively be possible, and even preferable, to omit such encapsulation, since a fully automated quality testing device 100 may be able to perform quality testing on component carrier structures 102 without encapsulation, so that even unencapsulated component carrier structures 102 may be subjected to further processing.

[0122] The component carrier structure 102 (encapsulated or unencapsulated) may then be transferred, for example by a further robot 120 of the handling unit 104, to a cleaning unit 152 configured to clean the component carrier structure 102. For example, the component carrier structure 102 may be rinsed in an ultrasonic bath.

[0123] The further alignment unit 154 may be configured to align the component carrier structure 102 before detecting and determining the test object 116 on the component carrier structure 102. For this purpose, one or more alignment features of the component carrier structure 102 (such as, for example, through-holes located at the corners) may be detected and used to spatially align the component carrier structure 102.

[0124] The aligned component carrier structure 102 may then be imaged. To this end, a detection unit 162 may be provided and configured to detect image data of the interior of the component carrier structure 102 (while exposed by said material removal).

[0125] Such image data may be transmitted to a determination unit 114. The latter may be configured to determine one or more predetermined test targets 116 of the component carrier structure 102. The test targets 116 may be predetermined features visible in the imaged cross-section of the component carrier structure 102 and may relate to features that are particularly meaningful with respect to quality assessment. Suitable characteristics or attributes of the test targets 116 of the component carrier structure 102 may be the diameter D of the drilled holes 158 (in particular laser-drilled or mechanically drilled holes that may be filled with plated copper), the distance L between such adjacent drilled holes 158, the thickness d of the conductive layer structure 130 (such as a patterned copper layer) and / or the electrically insulating layer structure 132 (such as a sheet of prepreg), the planarity of such layer structures 130 and / or 132, and the degree of delamination (see reference numeral 133) of such layer structures 130 and / or 132. The test object 116 described above is shown in top view 165 and side view 167, respectively, in Figure 2. However, another test object 116 (e.g., in a surface grinding scenario) could be a copper wire or multiple copper wires and the spaces between them.

[0126] Advantageously, the determination unit 114 is configured to process the image data to determine or recognize the predetermined test object 116. More specifically, the determination unit 114 may be configured to initially determine the predetermined test object 116 in a rough manner based on a detected first image of the component carrier structure 102. Furthermore, the determination unit 114 may then be configured to determine the predetermined test object 116 in a refined manner based on a detected second image of the component carrier structure 102, which is detected after detecting the first image and after etching the surface of the component carrier structure 102. In an alternative embodiment, a one-shot operation of the determination unit 114 may also be possible, where the determination unit 114 determines the test object 116 based on a single image. As a basis for the determination, the determination unit 114 may also have access to a database 128, for example to gain access to the test object 116 to be considered for the determination.

[0127] Highly advantageously, the determination unit 114 may be configured to determine the predetermined test object 116 by iteratively repeating a sequence comprising material removal (optionally including polishing and / or cleaning and / or etching), image detection, and image analysis, as indicated by the feedback loop 169. Such an iterative approach (which may be terminated when sufficient accuracy is achieved) may significantly improve the reliability of the quality test.

[0128] 2, an evaluation unit 118 is provided that is configured to evaluate the determined test objects 116 of the component carrier structure 102 in order to evaluate the quality of the component carrier structure 102. The evaluation unit 118 may be advantageously configured to evaluate the quality of the component carrier structure 102 based on characteristics of the determined test objects 116. More specifically, the evaluation unit 118 may be configured to evaluate the quality by classifying the component carrier structure 102 into one of a plurality of quality classes. It may be highly appropriate to automatically classify each component carrier structure 102 (and / or assigned larger body 160) into one of the following classes: "pass" (indicating that the component carrier structure 102 and / or larger body 160 has passed the quality test), "fail" (indicating that the component carrier structure 102 and / or larger body 160 has not passed the quality test), and "further analysis required" (indicating that the component carrier structure 102 and / or larger body 160 requires additional quality analysis, as the evaluation unit 118 is not yet in a position to make a meaningful decision about its quality). In the latter case, it may be possible to convey the component carrier structure 102 to a human operator for human analysis. The described communications and impact on the user may be exchanged between the user and the device 100 by means of an input / output unit 135 that is communicatively coupled to a control unit or processor 156.

[0129] In particular, the evaluation unit 118 may be configured to evaluate the quality by classifying each test object 116 individually, or preferably each attribute or characteristic of each test object 116 of the component carrier structure 102 individually, into one of a plurality of quality classes, in particular one class from a group of classes consisting of "pass," "fail," and "further analysis required." Only minor deviations in non-critical parameters may still allow the component carrier structure 102 to be classified as "pass." Defects may be classified as fatal or non-fatal based on the type of the particular defect and / or based on the severity of the particular defect. Such quality tests may have multiple criteria that may be determined individually to allow detailed decisions regarding quality and performance.

[0130] To support its evaluation task, the evaluation unit 118 may have an artificial intelligence module 134 configured to perform the evaluation using artificial intelligence, for example, by utilizing a neural network. Training data for training the artificial intelligence module 134, etc. may also be stored in the database 128.

[0131] The optional etching step of etching the exposed surface of the component carrier structure 102 may reveal additional features on the analyzed exposed surface of the component carrier structure 102, such as grain boundaries and plating lines, which may allow the evaluation unit 118 to more accurately evaluate the properties of the test object 116.

[0132] After the above evaluation, the analyzed component carrier structure 102 can be transported out of the apparatus 100. For this purpose, the handling unit 104 is provided with an outlet handling subunit 124, for example between the material removal unit 112 and the exit 108, configured to handle the component carrier structure 102 by means of at least one additional robot 120. As shown, the apparatus 100 has an outlet storage unit 138 (for example also of the magazine type) arranged at the exit 108 and configured to store a plurality of component carrier structures 102 in a stack after testing. The handling unit 104 can be configured to transfer the tested component carrier structure 102 through the exit 108 to the outlet storage unit 138. This can be achieved, for example, by means of a further robot 120.

[0133] As indicated by reference numeral 156, the apparatus 100 may comprise one or more processors or portions of processors that may be considered as control units for controlling the operation of the apparatus 100 and its above-mentioned components during quality testing of the component carrier structure 102.

[0134] Highly advantageously, the apparatus 100 may be configured to perform quality testing without human intervention between the inlet 106 and the outlet 108. Only optionally, user access may be possible via the input / output unit 135. The automated features of the apparatus 100 may accelerate quality testing and make quality testing more accurate while reducing the human resources required for quality testing. Furthermore, throughput may be increased.

[0135] 3 shows details of an apparatus 100 for performing quality testing of a component carrier structure 102 according to an exemplary embodiment of the present invention. FIG. 3 shows a particular embodiment showing elements of the apparatus 100 of FIG.

[0136] Input section 125 refers to the part of apparatus 100 between entrance 106 and material removal. Section cutting station 127 corresponds to the subsequent part of apparatus 100 where the section of component carrier structure 102 is created in a fully automated manner by grinding and subsequent polishing. Output section 129 refers to the part of apparatus 100 between section cutting station 127 and exit 108.

[0137] Figure 4 shows an apparatus 100 for processing a component carrier structure 102 for quality testing, in accordance with an exemplary embodiment of the present invention. More specifically, Figure 4 shows only a portion of such an apparatus 100, and additional elements of the apparatus of Figure 2 may also be combined with the elements shown in Figure 4. Figure 4 focuses on the steps involved in removing material from the component carrier structure 102 to expose one or more test targets 116 according to predetermined material removal objectives.

[0138] When a component carrier structure (such as that shown by reference number 102 in FIG. 2 embodied as a coupon) is inserted into the apparatus 100 via an inlet (see reference number 106 in FIG. 2 ), the component carrier structure 102 may be fed to an alignment unit 154 (shown in FIG. 4 ) configured to align the component carrier structure 102 before material removal (e.g. after being pre-processed as described with reference to FIG. 2 ). For this purpose, the component carrier structure 102 may be provided with alignment structures, such as through-holes at the corners of the component carrier structure 102 (see reference number 216 in FIG. 5 ).

[0139] Before, during and / or after alignment, the initial measurement unit 258 may be used to initially measure the component carrier structure 102, i.e., before any material is removed. The initial measurement unit 258 may, for example, be a camera that captures an image of the component carrier structure 102. Information such as the position, orientation and / or structural artifacts of the component carrier structure 102 may be identified by the initial measurement unit 258. According to such data captured by the initial measurement unit 258, subsequent material removal processes may be adjusted and / or the position and / or orientation of the component carrier structure 102 may be corrected.

[0140] The component carrier structure 102 then proceeds to a material removal unit 112, which may be configured to remove material from the component carrier structure 102 in order to expose one or more test targets 116 inside the component carrier structure 102 for quality testing. For example, the material removal unit 112 removes material from the component carrier structure 102 by grinding, preferably by cross-sectional grinding. Advantageously, the material removal unit 112 may be configured to remove material from the component carrier structure 102 by a coarse grinding stage using a larger grit size, followed by a fine grinding stage using a smaller grit size. This may allow smooth handling of the sensitive component carrier structure 102 and may prevent quality issues from occurring in the component carrier structure 102 due to processing during material removal.

[0141] 4, a progress measurement unit 250 may be provided in the apparatus 100 and may be preferably configured to measure the progress of material removal of the component carrier structure 102 during (and / or after) material removal. Various embodiments of the progress measurement unit 250 are described below with reference to FIG. 5 and FIGS. 7-10. As indicated generally by reference numeral 251, the progress measurement unit 250 may comprise one, any desired combination of two or more, or all of the following elements: optical progress measurement 253 using a camera to capture an image of the component carrier structure 102; electrical progress measurement 255 for performing electrical measurements on the test object 116 or sacrificial structure 224; a removed material quantification unit 142; measurement of spatial progress 257 of the material removal unit 112; detection of contact pressure 259 at the material removal unit 112; and detection of rotational speed 261 at the material removal unit 112. The aforementioned reference numerals relate to FIG. 5 and FIGS. 7-10.

[0142] After measuring the progress of the material removal process by the progress measurement unit 250, the analysis unit 252 of the apparatus 100 analyzes whether the measured progress meets the requirements of a predetermined material removal objective. For example, it may analyze whether the center 225 of the test object 116 is visible in a cross-sectional plane of the component carrier structure 102 exposed by the material removal.

[0143] A control unit 254 (which may be integrated into the processor 156 shown in FIG. 2 ) is provided for controlling further steps based on the results of the analysis. If the material removal objective has not yet been achieved, the control unit 254 controls the handling of the component carrier 102 such that the sequence of removing material by the material removal unit 112, measuring the progress by the progress measurement unit 250, and analyzing (by the analysis unit 252) whether the measured progress meets the above-mentioned requirements is repeated one or more times until the predetermined material removal objective is achieved. In this context, the control unit 254 may operate the component carrier structure 102 to iteratively repeat the sequence by handling the component carrier structure 102 along the adjustment loop 263.

[0144] Once the predetermined material removal objective has been achieved, the component carrier structure 102 is sent to a polishing unit 140 for polishing the exposed surface of the component carrier structure 102 after material removal. Polishing may flatten the surface of the component carrier structure 102 (exposed by the material removal) and reduce its roughness, which may improve the accuracy of quality testing because attributes of one or more test objects 116 become more visible on the captured image of the cross section.

[0145] After detecting an image of the now exposed, polished, and preferably cleaned surface of the component carrier structure 102 by the detection unit 162, the corresponding image data may be provided to a determination unit 114 configured to determine at least one test object 116 of the component carrier structure 102 on said image. The evaluation unit 118 may then evaluate a characteristic or attribute of the determined at least one test object 116 of the component carrier structure 102 in order to evaluate the quality of the component carrier structure 102.

[0146] Advantageously, the described apparatus 100 is configured to perform quality testing without human intervention, resulting in high accuracy quality testing at high throughput.

[0147] FIG. 5 shows, as an example of a component carrier structure 102, a coupon 200 having a sacrificial structure 224 used to control the progress of the material removal process, in accordance with an illustrative embodiment of the invention.

[0148] The coupon 200 has a PCB-type base plate 202 with a handling area 208 for robotic handling of the coupon 200 by the handling unit 104. An identifier 126, such as a QR code, allows identification of the coupon 200. A plurality of test objects 116, here embodied as copper-filled drill holes, are arranged in a test area 212 positioned away from the handling area 208. According to FIG. 5, the base plate 202 of the coupon 200 is provided with a machine-encoded feature 230 as a machine code that ensures proper orientation of the coupon 200 when inserted into the apparatus 100. In the illustrated embodiment, the machine-encoded feature 230 is embodied as a beveled edge of the (otherwise) substantially rectangular base plate 202.

[0149] 5 further comprises a plurality of alignment structures 216, here embodied as alignment through-holes, located at corner regions / corners of the base plate 202. The copper-free alignment structures 216 are realized as fiducial through-holes extending entirely through the base plate 202, allowing alignment by an optical camera of the apparatus 100. Such alignment may be advantageous during material removal and / or polishing and / or image detection.

[0150] Additionally, the coupon 200 of FIG. 5 includes a conductive sacrificial structure 224, which may be embodied, for example, as a metal insert in the base plate 202. The sacrificial structure 224 may be used to control the progress of a material removal unit 112, such as a grinding tool, while grinding the coupon 200. For this purpose, an electrode (not shown) of the apparatus 100 may be connected to the conductive sacrificial structure 224 during material removal from the right side of FIG. 5 . Initially, the electrode may measure an electrical signal at the conductive sacrificial structure 224. As the sacrificial structure 224 is removed during material removal, the electrical signal changes and eventually disappears when the sacrificial structure 224 is completely removed. This event corresponds to a scenario in which material removal exposes the center 225 of a metal-filled through-hole that constitutes the test object 116. Thus, the loss of the electrical signal detected at the sacrificial structure 224 may be used as a trigger to switch off the material removal unit 112 because a desired target position (corresponding to a predetermined material removal objective) with respect to the cross-section of the test object 116 has been reached. Thus, the sacrificial structure 224 may be intentionally removed during removal of material from the coupon 200 to expose the test subject 116. As a result, because the sacrificial structure 224 is positioned such that it is completely removed during removal of material from the coupon 200 when the center 225 of the test hole 220 is reached, the sacrificial structure 224 can be used to detect the progress of material removal up to subject exposure of the test subject 116. Alternatively, measuring the remaining resistance of the sacrificial structure 224 during material removal may be used as a basis for progress control.

[0151] In one embodiment, the sacrificial structure 224 is structured to indicate different portions required for process control. For example, a first portion (e.g., 90%) may be defined where a first grinding material can be used, a second portion (e.g., 7.5%) may be defined where a second grinding material (which may be finer than the first material) is used, and a third portion (e.g., the last 2.5%) may be defined where a third material can be used for fine grinding or polishing the remaining portion.

[0152] FIG. 6 shows a block diagram of a method for processing a component carrier structure 102 for quality testing according to an exemplary embodiment of the invention.

[0153] The method may start in block 265. Then, in block 267, a target position measurement may be performed on the component carrier structure 102. It is then evaluated whether the target position has been reached (see block 269). If not (see block 271), sample alignment is performed in block 273, followed by target preparation step 275. The process may then continue to block 267. If yes (see block 277), the component carrier structure 102 is polished, see block 279. It is then evaluated whether the surface quality is acceptable (see block 281). If not (see block 283), polishing is repeated. If yes (see block 285), the process ends in block 287.

[0154] FIG. 7 illustrates a component carrier structure 102 having a test object 116 prior to a material removal process and being monitored initially and / or continuously to adjust the material removal process, according to an exemplary embodiment of the invention.

[0155] The illustrated component carrier structure 102 may be, for example, a printed circuit board (PCB) with copper-plated drilled holes as the test object 116. The test object 116 has its center 225 located along a line 227, extending into the plane of the paper in Figure 7. As shown, the component carrier structure 102 has a beveled leading edge 229 that is subjected to a grinding material removal process.

[0156] Prior to removing material from the component carrier structure 102, the component carrier structure 102 may be measured using an initial measurement unit 258. In the illustrated embodiment, the initial measurement unit 258 is embodied as an optical camera. When capturing the image of the component carrier structure 102 shown in FIG. 7 , the initial measurement unit 258 may identify the slanted leading edge 229 of the component carrier structure 102. The material removal process performed by the material removal unit 112 may then be adjusted to remove material from the component carrier structure 102, taking into account the measurement results of the initial measurement unit 258. In the illustrated example, the material removal process may be performed such that the leading edge 229 of the processed component carrier structure 110 extends horizontally after grinding.

[0157] 7 further illustrates a monitoring unit 260, embodied here as an X-ray camera. The illustrated X-ray camera is configured to monitor the component carrier structure 102 once, periodically, or even continuously before, during, and / or after material removal from the component carrier structure 102. Specifically, the monitoring unit 260 can also detect copper-type test targets 116 inside the resin matrix of the component carrier structure 102. Based on this information, the material removal process can be adjusted accordingly. The progress of the material removal process can also be detected by the X-ray camera-type monitoring unit 260. During material removal (specifically, by grinding), the copper-type test targets 116, which can be detected by the monitoring unit 260, are also continuously removed. Based on the X-ray images captured by the monitoring unit 260, the material removal process can be controlled to stop precisely when a predetermined material removal objective is achieved. In the illustrated embodiment, the predetermined material removal objective is achieved when material removal is performed up to the line 227 and the center 225 of the test target 116 is exposed.

[0158] FIG. 8 shows a component carrier structure 102 having a test object 116 undergoing a material removal process by a material removal unit 112, in accordance with an exemplary embodiment of the present invention, wherein the advancement of the material removal unit 112 and / or the amount of material removed can be monitored for progress control.

[0159] The illustrated component carrier structure 102 may be, for example, a PCB having a drill hole completely filled with copper as the test target 116 positioned with its center 225 along line 227, which again defines a predetermined material removal objective where the material removal process should stop. This may further be ensured by progress measurement unit 250. In the illustrated embodiment, progress measurement unit 250 may use a combination of multiple sensed parameters to determine and control progress of material removal unit 112 up to but not beyond line 227. Alternatively, progress measurement unit 250 may use only one of the measures described below.

[0160] As shown, the progress measurement unit 250 has a schematically illustrated removed material quantification unit 142 configured to quantify the amount of material removed from the component carrier structure 102 by the material removal unit 112. The material removal unit 112 is here embodied as a grinding device that removes material from the component carrier structure 102 by grinding. The removed material (more specifically, the grinding chips) is indicated by reference numeral 141 in FIG. 8. Although not shown in FIG. 8, the progress measurement unit 250 may have a weighing device that determines the weight, and therefore the amount, of the removed material. If the characteristics of the component carrier structure 102 are known, it can be determined how much material should be removed to expose the test object 116 at the line 227.

[0161] In addition to or instead of the removed material quantification unit 142, the progress measurement unit 250 may comprise a removed material analysis unit configured to analyze (e.g., chemically analyze) the material removed from the component carrier structure 102 by the material removal unit 112. For example, such analysis may distinguish a time interval during which resin material is removed from the component carrier structure 102 and another time interval during which copper material is similarly removed from the component carrier structure 102. By such analysis, the progress of material removal may be determined when the structure of the component carrier structure 102 is known.

[0162] To further improve the resolution of the determination of the progress of material removal, the progress measurement unit 250 may also measure the spatial progress of the material removal unit 112 while removing material of the component carrier structure 102. This spatial progress is indicated schematically by arrow 143. As shown, the grinding tool 145 of the material removal unit 102 may be driven by a drive unit 147, such as an electric motor. By sensing the movement triggered by the drive unit 147 to drive the grinding tool 145, the spatial progress of the grinding tool 145 in the vertical direction according to FIG. 8 and into the component carrier structure 102 may be detected. This detection may also provide information that can be used to stop the material removal process at line 227, i.e., according to a predetermined material removal objective.

[0163] Furthermore, the progress measurement unit 250 may be configured to measure progress based on detecting the contact pressure of the material removal unit 112 against the component carrier structure 102 while removing material from the component carrier structure 102. For this purpose, the material removal unit 112 may be provided with a pressure sensor 149, preferably near the front side of the grinding device 145. As the grinding device 145 moves forward relative to the component carrier structure 102, the contact pressure may be detected by the pressure sensor 149. While the grinding device 145 removes the relatively soft resin material from the component carrier structure 102, the measured contact pressure may be small. As the grinding device 145 reaches the harder copper material of the test object 116 and begins to partially remove it, the detected contact pressure increases. It may be maximum when the line 227, which corresponds to the maximum copper cross-section, is reached. Therefore, the time dependence of the contact pressure may also be used to determine and control progress. In addition to or instead of contact pressure, progress can also be measured based on the rotational speed of the rotatable body 256 of the material removal unit 112 while removing material from the component carrier structure 102 .

[0164] FIG. 9 shows a component carrier structure 102 having a test object 116 and a sacrificial structure 224 undergoing a material removal process by a material removal unit 112 according to an exemplary embodiment of the present invention, where electrical signals can be detected in the sacrificial structure 224 and / or the test object 116 for progress control.

[0165] The progress measurement unit 250 according to Fig. 9 is configured to measure the progress of the material removal unit 112 by electrically measuring conductive structures in the form of test objects 116 and / or sacrificial structures 224 of the component carrier structure 102. The test objects 116 are again embodied as drill holes completely filled with copper, as in Fig. 8. The sacrificial structures 224 are also made of copper and function in a similar manner to the sacrificial structures 224 of Fig. 5. The center 225 of the test object 116 and the backside of the sacrificial structures 224 are positioned along a line 227 that defines a predetermined material removal target where the material removal process will stop.

[0166] As shown, the progress measurement unit 250 includes an electrical detection unit 151 (capable of measuring voltage or current, for example) electrically coupled to the sacrificial structure 224 and / or one or more test objects 116. During material removal from the component carrier structure 102 by the material removal unit 112, starting from the bottom of FIG. 9 , the material removal unit 112 will at some point reach the sacrificial structure 224 and begin removing it. As a result, the ohmic resistance of the remaining copper material of the ground sacrificial structure 224 increases, which can be detected by the electrical detection unit 151. When the sacrificial structure 224 is completely removed, i.e., when it reaches a line 227 corresponding to a predetermined material removal objective, the electrical signal emanating from the sacrificial structure 224 disappears, and this disappearance can be used as a trigger to stop the material removal process.

[0167] In addition to, or instead of, capturing the electrical signal at the sacrificial structure 224, it is also possible to perform such measurements on one or more test targets 116, which are also made of conductive copper. When the material removal process reaches the lower end of the test target 116, the ohmic resistance of the test target 116 begins to increase, which can be detected by the electrical detection unit 151. When line 227 is reached, half of the material of the test target 116 is removed. In this scenario, the ohmic resistance, and therefore the electrical signal detected by the electrical detector 151, has a characteristic value, which can be detected. The material removal process can then be terminated. It is also possible to detect the event of reaching line 227 by analyzing the slope of the electrical signal, since this corresponds to a turning point in the slope.

[0168] FIG. 10 illustrates a component carrier structure 102 having a test object 116 and a mechanical stop 262 for preventing excessive material removal from a progress control perspective, in accordance with an exemplary embodiment of the present invention.

[0169] The illustrated mechanical stop 262 can be positioned such that it is configured to abut the component carrier structure 102 to disable excessive material removal of the component carrier structure 102 by the material removal unit 112. In other words, when the material removal unit 110 reaches the line 227 corresponding to the predetermined material removal objective, the material removal unit 112 will abut against the preferably hardened abutment surface 153 of the mechanical stop 262.

[0170] 10, the progress measurement unit 250 can also be configured to measure progress by optically detecting one or more images of the component carrier structure 102, as shown schematically in FIG. 10 by reference numeral 155. On such images, a cross-section of the respective test target 116, here embodied as a copper-plated through-hole, is visible. In a first scenario, indicated by reference numeral 157, the exposed surface of the component carrier structure 102 shows straight walls of the cylindrical test target 116, which exhibit appropriately (e.g., "appropriately" according to one or more evaluation criteria, which may be stored in a database) vertical cross-sectional sidewalls. The component carrier structure 102 can therefore proceed to quality determination and evaluation. In a second scenario, indicated by reference numeral 159, the exposed surface of the component carrier structure 102 shows slanted sidewalls of the cylindrical test target 116, which exhibit incorrectly (e.g., "incorrectly" according to one or more evaluation criteria, which may be stored in a database) tilted cross-sectional sidewalls of the component carrier structure 102. A correction by additional material removal may then be triggered.

[0171] It should be noted that the word "comprising" does not exclude other elements or steps and "a" or "an" does not exclude a plurality. Also, elements described in association with different embodiments may be combined.

[0172] It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.

[0173] The implementation of the present invention is not limited to the preferred embodiment shown in the drawings and described above, but instead many variations are possible that use the solutions shown and the principles according to the invention, even in radically different embodiments.

Claims

1. 1. An apparatus for processing a component carrier structure for quality testing, the apparatus comprising: a material removal unit configured to remove material of the component carrier structure to expose at least one test object of the component carrier structure for undergoing the quality test, the at least one test object comprising at least one of the group consisting of at least one drill hole and at least one layer structure; a progress measurement unit configured to measure the progress of the removal of the material of the component carrier structure; an analysis unit configured to analyze whether the measured progress meets the requirements of a predetermined material removal objective; a control unit configured to control, based on a result of said analysis, whether the sequence of removing said material, measuring the progress of said material removal, and analyzing whether said measured progress meets said requirements of said predetermined material removal objective must be repeated; a determining unit configured to determine the at least one test object of the component carrier structure after the removal of the material; and an evaluation unit configured to evaluate the determined at least one test object characteristic of the component carrier structure in order to evaluate a quality of the component carrier structure, the characteristic comprising at least one of the group consisting of a diameter of a drill hole, a distance between adjacent drill holes, a width of a conductive trace of a conductive layer structure, a distance between adjacent conductive traces of a conductive layer structure, a thickness of a layer structure, a planarity of a layer structure, delamination of a layer structure, and any characteristic of a printed circuit board type component carrier structure; An apparatus comprising:

2. Features include: the control unit is configured to iteratively repeat the sequence of removing the material, measuring the progress of the material removal, and analyzing whether the measured progress meets the requirements one or more times until the predetermined material removal objective is achieved; The control unit is configured to iteratively repeat the sequence in a regulation loop. The apparatus of claim 1 , comprising at least one of:

3. The apparatus of claim 1 or 2, wherein the material removal unit is configured to remove the material of the component carrier structure by grinding.

4. Features include: the material removal unit is configured to remove the material of the component carrier structure by one of the group consisting of cross-section grinding and surface grinding; The material removal unit is configured to remove material from the component carrier structure by a coarse grinding stage followed by a fine grinding stage. The apparatus of claim 3 , comprising at least one of:

5. Features include: a polishing unit for polishing the exposed surface of the component carrier structure after removing the material; the progress measurement unit is configured to measure the progress during the removal of the material by the material removal unit; The progress measurement unit is configured to measure the progress by optically detecting an image of the component carrier structure. The device according to any one of claims 1 to 4, comprising at least one of:

6. The apparatus according to any one of claims 1 to 5, wherein the progress measurement unit is configured to measure the progress by electrically measuring electrical signals on conductive structures of the component carrier structure.

7. Features include: the conductive structure belongs to one of the group consisting of the at least one test target and sacrificial structure of the component carrier structure; The progress measurement unit is configured to measure the progress during removal of the material to expose the at least one test object by detecting an electrical signal of the conductive structure to be at least partially removed, the conductive structure being configured to be used to detect the progress of the removal of the material to the exposure of the at least one test object according to the predetermined material removal objective. The apparatus of claim 6 , comprising at least one of:

8. Features include: the progress measurement unit includes a removed material quantification unit configured to quantify an amount of the material removed from the component carrier structure by the material removal unit; the progress measurement unit is configured to measure the progress based on a spatial progress of the material removal unit while removing the material of the component carrier structure; the progress measurement unit is configured to measure the progress based on detection of a contact pressure of the material removal unit against the component carrier structure while removing the material of the component carrier structure; The progress measurement unit is configured to measure the progress based on detecting a rotational speed of a rotatable body of the material removal unit while removing the material of the component carrier structure. The device according to any one of claims 1 to 7, comprising at least one of:

9. an initial measurement unit configured to initially measure the component carrier structure before removing the material; The apparatus according to any one of claims 1 to 8, wherein the material removal unit is configured to remove the material of the component carrier structure based on a measurement result of the initial measurement unit.

10. Features include: having a monitoring unit, in particular an X-ray device, configured to monitor, in particular continuously monitor, said component carrier structure at least during at least a portion of said sequence; the predetermined material removal objective is to reach the center of the test object, in particular a drill hole or a conductive structure, of the component carrier structure; a mechanical stop configured to abut the material removal unit to prevent excessive removal of the material from the component carrier structure by the material removal unit; the device is configured to perform the quality test without human intervention; In particular, an alignment unit configured to align the component carrier structure prior to removing the material based on detection of at least one alignment structure of the component carrier structure. The device according to any one of claims 1 to 9, comprising at least one of:

11. 1. A method for processing a component carrier structure for quality testing, the method comprising: removing, by a material removal unit, material of the component carrier structure to expose at least one test object of the component carrier structure for undergoing the quality test, the at least one test object comprising at least one of the group consisting of at least one drill hole and at least one layer structure; measuring the progress of the removal of the material of the component carrier structure by a progress measurement unit; analyzing, by an analysis unit, whether the measured progress meets the requirements of a predetermined material removal objective; controlling, by a control unit, based on the results of said analysis, whether the sequence of removing said material, measuring the progress of said material removal, and analyzing whether said measured progress meets said requirements of said predetermined material removal objective must be repeated; determining, by a determining unit, the at least one test object of the component carrier structure after removing the material; and evaluating, by an evaluation unit, the determined at least one test object characteristic of the component carrier structure in order to evaluate a quality of the component carrier structure, the characteristic comprising at least one of the group consisting of a diameter of a drill hole, a distance between adjacent drill holes, a width of a conductive trace of a conductive layer structure, a distance between adjacent conductive traces of a conductive layer structure, a thickness of a layer structure, a planarity of a layer structure, delamination of a layer structure, and any characteristic of a printed circuit board type component carrier structure; A method for providing the above.

12. Features include: The method includes repeating, by the control unit, the sequence of removing the material, measuring the progress of the material removal, and analyzing whether the measured progress meets the requirements one or more times iteratively until the predetermined material removal objective is achieved; The component carrier structure comprises one of the group consisting of a panel including a plurality of connected preforms of a component carrier, an array including a plurality of connected preforms of a component carrier, a component carrier preform, a coupon, and a component carrier, specifically one of a printed circuit board and an integrated circuit board; The method includes performing the quality test without human intervention. The method of claim 11 , comprising at least one of:

13. 13. A computer readable medium having stored thereon a computer program for processing component carrier structures for quality testing, the computer program being adapted, when executed by one or more processors, to perform and / or control the method according to claim 11 or 12.

14. 13. A program for processing component carrier structures for quality testing, adapted to cause one or more processors to perform and / or control the method according to claim 11 or 12.

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