Device for optically inspecting through-holes in component carriers

Abstract

To provide an apparatus for efficiently optically inspecting through-holes in thick component carriers. [Solution] The apparatus 100 comprises an electromagnetic radiation source 110 which emits a first electromagnetic radiation beam 111 along a trajectory T1, a sample holder 120 which holds a component carrier 101 to be investigated, the component carrier having at least one through hole 102, the sample holder configured to hold the component carrier in position such that the trajectory of the first electromagnetic radiation beam passes through the at least one through hole, and is arranged to receive the first electromagnetic radiation beam after it has passed through the at least one through hole, and is characterized in that it comprises an optical element configured to modify at least one physical parameter of the first electromagnetic radiation beam to provide a second electromagnetic radiation beam, and an electromagnetic radiation detector which receives the second electromagnetic radiation beam.

Description

[Technical field]

[0001] The present invention relates to a component carrier. [Background technology]

[0002] In the context of the growth of product functionality of component carriers carrying one or more electronic components, and the intensified miniaturization of such components, as well as the increase in the number of components mounted on component carriers such as printed circuit boards, ever more powerful arrays of components or packages carrying multiple components with multiple contacts or connections and ever smaller spacing between the contacts are being used. Removal of heat generated by such components and the component carrier itself during operation becomes an ever greater challenge. At the same time, the component carrier should be mechanically robust and electrically reliable so that it can operate under harsh conditions.

[0003] In particular, efficiently inspecting component carriers during the manufacturing process is a challenge.

[0004] 3 shows an example from the prior art, where a component carrier 201, which is a thin panel, is optically inspected using a light source 210 and a camera 240. The thin panel comprises through-holes 202 forming an identification area (pattern). As can be seen, a light beam 211 from the light source 210 passes through the through-holes 202 and is detected by the camera 240. The image taken by the camera shows sufficient quality.

[0005] 4 shows a further example from the prior art, where the component carrier 201 is a thick panel, i.e. with a thickness of more than 1.5 mm. In this case it can be seen that the image taken by the camera 240 is not of sufficient quality, since many of the through-holes 202 are no longer visible in the taken image.

[0006] Figure 5 shows an apparatus from the prior art for carrying out the investigation described above with respect to figures 3 and 4. It can be seen that the light 211 from the light source 210 is not focused sufficiently on the camera. However, this problem cannot be solved because the space during production of the component carrier is very limited and therefore the height of the camera is not adjustable.

[0007] Especially during the manufacturing process, it may be necessary to efficiently probe (thick) component carriers with regard to their through-holes. Summary of the Invention

[0008] According to an exemplary embodiment of the present invention, an apparatus for inspecting a component carrier is provided, the apparatus comprising: i) an electromagnetic radiation source that emits a first electromagnetic radiation beam along a trajectory; ii) a sample holder for holding a component carrier to be investigated, the component carrier having at least one through hole, the sample holder configured to hold the component carrier in place such that a trajectory of the first electromagnetic radiation beam passes through the at least one through hole; iii) an optical element positioned to receive the first electromagnetic radiation beam after passing through the at least one through hole, and configured to modify at least one physical parameter (e.g., focal length, direction, etc.) of the first electromagnetic radiation beam to provide a second electromagnetic radiation beam; and iv) an electromagnetic radiation detector receiving the second electromagnetic radiation beam.

[0009] According to another exemplary embodiment of the present invention, an assembly is provided, the assembly comprising: i) an apparatus as described above; ii) a component carrier disposed within the sample holder and having a plurality of through holes.

[0010] According to another exemplary embodiment of the present invention, a method for inspecting a component carrier is provided, the method comprising the steps of: i) projecting a first beam of electromagnetic radiation along a trajectory; ii) holding in place a component carrier to be inspected, the component carrier having at least one through hole; iii) passing a first trajectory-aligned electromagnetic radiation beam through at least one through-hole of the held component carrier; and thereafter iv) modifying at least one physical parameter of the first electromagnetic radiation beam by using an optical element to provide a second electromagnetic radiation beam; and v) an electromagnetic radiation detector receiving the second beam of electromagnetic radiation.

[0011] In the context of this document, the term "component carrier" may refer to any support structure capable of receiving one or more components thereon and / or therein, in particular to provide mechanical support and / or electrical connectivity. In other words, the component carrier may be configured as a mechanical and / or electronic carrier of the components. In particular, the component carrier may be one of a printed circuit board, an organic interposer, a metal core substrate, an inorganic substrate, and an IC (integrated circuit) substrate. The component carrier may also be a mixed substrate that combines different of the above-mentioned types of component carriers.

[0012] In the context of this document, the term "optical element" may in particular refer to a device suitable for modifying at least one physical parameter of a first electromagnetic radiation beam (e.g., a light beam) to obtain a second electromagnetic radiation beam (e.g., also a light beam), said physical parameter being different for the first and second electromagnetic radiation beams. In one example, the physical parameter may be a focal length and the optical element may comprise a focusing lens. In another example, the physical parameter may be a direction / trajectory in air and the optical element may comprise a mirror or a prism that modifies the trajectory of the first electromagnetic radiation beam into a further trajectory of the second electromagnetic radiation device.

[0013] According to an exemplary embodiment, the utility model is based on the idea that the through-holes of a component carrier can be efficiently interrogated (during the manufacturing process) if a first electromagnetic radiation beam passes through the through-holes (e.g. forming an identification area) and then at least one physical parameter is modified by an optical element to provide a second electromagnetic radiation beam. In this way, it may be possible to flexibly adapt the physical parameters of the beam to the current situation (especially the space requirements) in an advantageous manner.

[0014] It can be difficult to investigate through-holes in a component carrier, especially when the component carrier is thick (e.g. with a thickness of 1.5 mm or more). Conventionally, a light source emits a light beam through said through-hole. However, in this case it can be impossible to obtain sufficient quality data (of images). See for example FIG. 4. Hereby, a particular challenge is that the space in the manufacturing process (and system) is very limited and the photodetector can only be placed if the available space allows this. As a result, the distance between the light source and the photodetector is generally too short to establish a suitable focal length and / or emission angle.

[0015] The inventors have surprisingly found that the problem of high-quality through-hole inspection during component carrier manufacturing may be solved by applying optical elements in the beam path that adapt their physical parameters in an efficient manner, without being limited by the available space. In this way, high image quality is obtained (e.g. by adjusting the camera focus) without the need to change the height of the electromagnetic radiation detector.

[0016] Further exemplary embodiments of the method and the component carrier are described below.

[0017] In one embodiment, the electromagnetic radiation source comprises a light source.

[0018] In one embodiment, the electromagnetic radiation detector comprises a camera.

[0019] In one embodiment, the optical element is configured to change the focal length (and / or the radiation angle) of the first electromagnetic radiation beam such that the focus of the second electromagnetic radiation beam is different from the focus of the first electromagnetic radiation beam. In particular, the optical element comprises a focusing lens. In this way, the second electromagnetic radiation beam may be efficiently focused (using an additional focusing device) to obtain high quality data without any need to change the position of the detector.

[0020] In an embodiment, the optical element is configured to modify the trajectory of the first electromagnetic radiation beam such that the trajectory of the first electromagnetic radiation beam is different from the further trajectory of the second electromagnetic radiation beam. In particular, the optical element comprises a mirror, a prism, a grid, or a wedge. In this way, the second electromagnetic radiation beam may be efficiently focused (by stretching the trajectory) to obtain high quality data without any need to modify the height of the detector.

[0021] In one embodiment the optical element comprises a mirror which is oriented at an angle between 1 and 89°, in particular between 30 and 50°, more in particular (approximately) 45° relative to the trajectory of the first electromagnetic radiation beam.

[0022] In an embodiment, the electromagnetic radiation detector is arranged shifted with respect to an axis parallel to the trajectory of the first electromagnetic radiation beam, in particular the shift is between 1 and 90°, in particular between 30 and 90°, more in particular 90°, which may allow flexible positioning of the detector.

[0023] In one embodiment, the component carrier is a thick panel having a thickness of 1.5 mm or more, which may provide the advantage that even through-holes in thick component carriers can now be probed.

[0024] In one embodiment, the plurality of through holes forms an identification area, which may enable an efficient and robust manufacturing process.

[0025] In one embodiment, the component carrier is shaped as a plate. This contributes to a compact design, while the component carrier still provides a large base for mounting components thereon. Furthermore, due to its small thickness, the bare die, as an example, especially for embedded electronic components, can be conveniently embedded in a thin plate, such as a printed circuit board.

[0026] In one embodiment, the component carrier is configured as one of the group consisting of a printed circuit board, a substrate (particularly an IC substrate), and an interposer.

[0027] In the context of the present application, the term "printed circuit board" (PCB) may in particular refer to a plate-like component carrier formed by laminating several conductive layer structures with several electrically insulating layer structures, for example by applying pressure and / or by supplying thermal energy. As a preferred material for PCB technology, the conductive layer structures are made of copper, but the electrically insulating layer structures may also comprise resin and / or glass fibers, the so-called prepreg or FR4 material. The various conductive layer structures may be connected to each other in the desired way by forming holes through the laminate, for example by laser drilling or mechanical drilling, and by filling them partially or completely with a conductive material, in particular copper, to form vias or any other through-hole connections. The filled holes either connect the whole stack (through-hole connections extending through several layers or the whole stack) or they connect at least two conductive layers and are called vias. Similarly, optical interconnections can be formed through the individual layers of the stack to receive electro-optical circuit boards (EOCBs). Apart from one or more components that may be embedded in the printed circuit board, the printed circuit board is usually configured to receive one or more components on one or both opposing faces of the plate-like printed circuit board. They may be connected to each major face by soldering. The dielectric part of the PCB may be composed of a resin containing reinforcing fibers (such as glass fibers).

[0028] In the context of the present application, the term "substrate" may in particular refer to a small component carrier. The substrate may be a relatively small component carrier with respect to a PCB, on which one or more components may be mounted and may act as a connection medium between one or more chips and a further PCB. For example, the substrate may have substantially the same size as the components (particularly electronic components) mounted thereon (for example in the case of a chip-scale package (CSP)). More specifically, the substrate may be understood as a carrier of electrical connections or electrical circuitry as well as a component carrier comparable to a printed circuit board (PCB), but with a much higher density of connections arranged laterally and / or vertically. The lateral connections may for example be conductive tracks and the vertical connections may for example be drilled holes. These lateral and / or vertical connections are arranged in the substrate and can be used to provide electrical, thermal and / or mechanical connections between housed or unhoused components (such as bare dies), in particular of IC chips, and printed circuit boards or intermediate printed circuit boards. The term "substrate" therefore also includes "IC substrate". The dielectric portion of the substrate may be composed of a resin containing reinforcing particles (such as reinforcing spheres, especially glass spheres).

[0029] The substrate or interposer may comprise or consist of at least one layer of glass, silicon (Si), and / or photoimageable or dry-etchable organic materials such as epoxy-based build-up materials (such as epoxy-based build-up films), or polymeric compounds such as polyimides or polybenzoxazoles (which may or may not contain photosensitive and / or thermosensitive molecules).

[0030] In one embodiment, the at least one electrical insulation layer structure comprises at least one of the group consisting of resins or polymers, such as epoxy resins, cyanate ester resins, benzocyclobutene resins, bismaleimide triazine resins, polyphenylene derivatives (e.g., polyphenylene ether (PPE)-based), 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, for example made of glass (multilayer glass), can also be used to form composite materials. Semi-cured resins combined with reinforcing agents, such as fibers impregnated with the above-mentioned resins, are called prepregs. These prepregs are often named after their properties, for example FR4 or FR5 to represent their flame retardant properties. Usually, prepregs, especially FR4, are preferred for rigid PCBs, but other materials may also be used, especially epoxy-based build-up materials (such as build-up films) or photoimageable dielectric materials. For high frequency applications, high frequency materials such as polytetrafluoroethylene, liquid crystal polymers, and / or cyanate ester resins may be preferred. Besides these polymers, low temperature co-fired ceramics (LTCC) or other low, ultra-low, or extremely low DK materials may be applied within the component carrier as an electrically insulating structure.

[0031] 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, tungsten, and magnesium. Copper is typically preferred, but other materials or coatings thereof are also possible, particularly those coated with superconducting materials or conductive polymers, such as graphene or poly(3,4-ethylenedioxythiophene) (PEDOT), respectively.

[0032] At least one component may be embedded in the component carrier and / or surface mounted on the component carrier. Such components may be selected from the group consisting of non-conductive inlays, conductive inlays (such as metal inlays, preferably comprising copper or aluminum), heat transfer units (e.g. heat pipes), light-guiding elements (e.g. light guides or light guide connections), electronic components, or combinations thereof. Inlays may be, for example, metal blocks with or without insulating material coatings (IMS inlays) and may be embedded or surface mounted for the purpose of facilitating heat dissipation. Suitable materials are defined according to their heat conductivity, which should be at least 2 W / mK. Such materials are often based on metals, metal oxides, and / or ceramics, such as, for example, but not limited to, copper, aluminum oxide (Al2O3), or aluminum nitride (AlN). Other geometries with increased surface area are often also used to improve heat exchange capabilities.Further, the 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 other data memories), filters, integrated circuits (such as field programmable gate arrays (FPGAs), programmable array logic (PALs), general array logic (GALs), and 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 semiconductor (CMOS), junction field effect transistors (JFETs), or insulated gate field effect transistors (IGFETs)). The components may be: semiconductor elements, such as silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium oxide (Ga2O3), indium gallium arsenide (InGaAs), and / or any other suitable inorganic compounds), optoelectronic interface elements, light emitting diodes, photocouplers, voltage converters (e.g., DC / DC converters or AC / DC converters), encryption components, transmitters and / or receivers, electromechanical converters, sensors, actuators, microelectromechanical systems (MEMS), microprocessors, capacitors, resistors, inductances, batteries, switches, cameras, antennas, logic chips, and energy harvesting units. However, other components may also be embedded in the component carrier. For example, magnetic elements may be used as components. Such magnetic elements may be permanent magnetic elements (ferromagnetic elements, antiferromagnetic elements, multiferroic elements, or ferrimagnetic elements, such as ferrite cores, etc.) or may be paramagnetic elements. However, the component may also be an IC substrate, an interposer or a further component carrier, for example in a board-in-board configuration. The components may be surface mounted on the component carrier and / or embedded therein. Furthermore, other components may also be used as components, in particular those which generate and emit electromagnetic radiation and / or are sensitive with respect to electromagnetic radiation propagating from the environment.

[0033] In one embodiment, the component carrier is a stacked component carrier, in which the component carrier is a composite of multiple layers that are stacked and connected together by application of pressure and / or heat.

[0034] After processing the internal layer structure of the component carrier, one or both opposing main faces 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 build-up can be continued until the desired number of layers is obtained.

[0035] After the formation of the stack of electrically insulating and conductive layer structures has been completed, it is possible to proceed to a surface treatment of the resulting layer structure or component carrier.

[0036] In particular, an electrically insulating solder resist may be applied to one or both opposing main surfaces of the layer stack or the component carrier for surface treatment. For example, such a solder resist may be formed on the entire main surface, and the layer of solder resist may then be patterned to expose one or more conductive surface portions that are to be used to electrically couple the component carrier to peripheral electronics. Surface portions of the component carrier that remain covered with the solder resist, in particular surface portions that contain copper, may be efficiently protected from oxidation or corrosion.

[0037] Also, with regard to surface treatment, it is possible to selectively apply a surface finish to exposed conductive surface portions of the component carrier. Such a surface finish may be a conductive coating material to exposed conductive layer structures (e.g. pads, conductive tracks, etc., comprising or consisting of, in particular, copper) on the surface of the component carrier. If such exposed conductive layer structures are left unprotected, the exposed conductive component carrier material (e.g. copper) may oxidize, reducing the reliability of the component carrier. Thus, a surface finish may 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 (e.g. 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 Preservatives (OSP), Electroless Nickel Immersion Gold (ENIG), Electroless Nickel Immersion Palladium Immersion Gold (ENIPIG), gold (especially hard gold), chemical tin, nickel gold, nickel palladium, and the like.

[0038] The above-defined and further aspects of the present utility model are apparent from and will be elucidated with reference to the example embodiments described hereinafter. [Brief description of the drawings]

[0039] [Figure 1] FIG. 2 shows an apparatus for inspecting a component carrier according to an illustrative example of the present invention, in which the optical element comprises a mirror. [Diagram 2] FIG. 2 shows an apparatus for inspecting a component carrier according to a further illustrative example of the present invention, in which the optical element comprises a focusing lens. [Diagram 3] FIG. 1 shows an optical investigation of through holes in a thin panel from the prior art. [Figure 4]FIG. 1 shows an optical investigation of a through-hole in a thick panel from the prior art. [Diagram 5] FIG. 1 shows an apparatus for inspecting a component carrier according to the prior art. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The illustrations in the drawings are schematic: in different drawings, similar or identical elements are provided with the same reference signs.

[0041] FIG. 1 shows an apparatus 100 for investigating a component carrier 101, the apparatus 100 comprising an electromagnetic radiation source 110 for emitting a first electromagnetic radiation beam 111 along a trajectory T1. In this example, the electromagnetic radiation source 110 is configured as a light source for emitting a light beam. The apparatus 100 comprises a sample holder 120 for holding in position the component carrier 101 to be investigated. The component carrier 101 has a number of through holes 102 serving as ID areas. The sample holder 120 is configured to hold the component carrier 101 in position such that the trajectory T1 of the first electromagnetic radiation beam 111 passes through the number of through holes 102. The apparatus 100 further comprises an optical element 130 arranged behind the component carrier 101 to receive the first electromagnetic radiation beam 111. The optical element 130 is thereby configured to modify at least one physical parameter of the first electromagnetic radiation beam 111 to provide a second electromagnetic radiation beam 112. In the example of Fig. 1, the optical element 130 comprises a mirror and the physical parameter to be changed is the spatial direction (trajectory) of the first electromagnetic radiation beam 111. In this example, a further trajectory T2 is changed at an angle of 90° with respect to the trajectory T1. Furthermore, the apparatus 100 comprises an electromagnetic radiation detector 140 which receives the second electromagnetic radiation beam 112. In this example, the detector comprises a camera. Although the space is very limited, the light from the light source 110 can be guided to the camera 140 so that a perfect focal length is obtained and high quality images can be taken and examined.

[0042] Figure 2 shows essentially the same apparatus as Figure 1, but the optical element 130 comprises a focusing lens configured to change the focal length of the first electromagnetic radiation beam 111 such that the focal point of the second electromagnetic radiation beam 112 differs from the focal point of the first electromagnetic radiation beam 111.

[0043] 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.

[0044] It should also be noted that reference signs in the claims shall not be construed as limiting the scope of the claims.

[0045] The realization of the present utility model is not limited to the preferred embodiment shown in the drawings and described above, instead several variants are possible that use the solutions shown and the principles according to the present utility model, even in the case of fundamentally different embodiments.

Claims

1. 1. An apparatus for inspecting a part carrier, comprising: an electromagnetic radiation source that emits a first electromagnetic radiation beam along a trajectory; a sample holder for holding the component carrier to be investigated, the component carrier having at least one through hole; the sample holder is configured to hold the component carrier in place such that the trajectory of the first electromagnetic radiation beam passes through the at least one through-hole. A sample holder; an optical element positioned to receive the first electromagnetic radiation beam after passing through the at least one through hole, and configured to modify at least one physical parameter of the first electromagnetic radiation beam to provide a second electromagnetic radiation beam; an electromagnetic radiation detector that receives the second beam of electromagnetic radiation; An apparatus comprising:

2. The apparatus of claim 1 , wherein the source of electromagnetic radiation comprises a light source.

3. 3. The apparatus of claim 1 or 2, wherein the electromagnetic radiation detector comprises a camera.

4. the optical element is configured to modify a focal length of the first electromagnetic radiation beam, thereby 4. An apparatus according to claim 1, wherein the focal length of the second electromagnetic radiation beam is different to the focal length of the first electromagnetic radiation beam.

5. the optical element is configured to modify the trajectory of the first electromagnetic radiation beam, thereby:

5. Apparatus according to any one of the preceding claims, wherein the trajectory of the first electromagnetic radiation beam is different from a further trajectory of the second electromagnetic radiation beam.

6. The apparatus of claim 5 , wherein the optical element comprises a mirror oriented at an angle of 30 to 60 degrees with respect to the trajectory of the first electromagnetic radiation beam.

7. 7. Apparatus according to claim 5 or 6, wherein the electromagnetic radiation detector is arranged in a shifted manner with respect to the trajectory of the first electromagnetic radiation beam, the shift being between 30 and 90° with respect to an axis parallel to the trajectory.

8. 8. Apparatus according to any one of claims 1 to 7, wherein the component carrier is a thick panel having a thickness of 1.5 mm or more.

9. An apparatus according to any one of claims 1 to 8, the component carrier disposed within the sample holder; The assembly wherein the component carrier has a plurality of through holes.

10. 10. The assembly of claim 9, wherein the plurality of through holes form an identification area.

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