Carrier plate with protective function and manufacturing process

Abstract

Carrier plate (TP) for an electrical component (BE) - with a mechanically stable base body (GK) which has external contacts (AK) on a bottom side (US) and connection surfaces (AF) for the component (BE) on a top side (OS), - with a recess (AN) in which an ESD protection element (SE) discrete from the base body (GK) is at least partially embedded, wherein the electrical connections of the protection element (SE) are accessible from the top (OS) or the bottom (US) of the base body (GK), - in which the protective element (SE) is mechanically firmly embedded in the recess (AN) of the base body (GK) by means of a connecting element (VM), wherein the connecting element (VM) does not fill all the spaces between the protective element (SE) and the outer walls of the recess (AN), - in which the electrical connections of the protective element (SE) are connected via a structured metallic layer (SM) to the contact surfaces (AF) on the top (OS) or the external contacts (AK) on the bottom (US).

Description

[0001] The application concerns a carrier plate with a protective function for an electrical component and a low overall height.

[0002] Varistors can be used to protect sensitive equipment, components, and networks against ESD (Electrostatic Discharge). These are non-linear components whose resistance drops sharply when a certain applied voltage is exceeded. Varistors are therefore suitable for safely dissipating overvoltage pulses. They are made of a zinc oxide ceramic with a granular structure.

[0003] Varistors are difficult to integrate into multilayer ceramics and are therefore usually used as discrete components.

[0004] Discrete varistors, on the other hand, have primarily geometric advantages; for example, they can be manufactured very thin. However, this increases the risk of breakage for the panels.

[0005] Discrete components with varistor function or, more generally, with ESD protection function are soldered directly onto a ceramic substrate, a leadframe, a circuit board or a printed circuit board and electrically connected to the component to be protected.

[0006] It is also possible to integrate such protective elements into a laminate during its production.

[0007] Furthermore, it is possible to position the protective element in a recess of the substrate, carrier board, or laminate in such a way that it is adjacent to other electrically conductive structures intended for connection with further components. While this results in a low component height, it requires sufficient assembly area.

[0008] It is also possible to use a varistor ceramic as a component substrate and to integrate the protective function into the substrate.

[0009] US patent 2007 / 0075323A1 discloses an arrangement in which an LED is mounted on a carrier serving as a heat sink. A varistor element is arranged in a recess of the heat sink.

[0010] US patent 7,528,422 B2 discloses an LED that is arranged in a recess of a substrate. The LED is connected to an ESD protection component.

[0011] From JP H01-99 227 A a hybrid integrated circuit structure is known for which questions of heat dissipation are discussed.

[0012] US 2014 / 0 301 054 A1 shows an arrangement in which a Zener diode is potted with a resin to serve as an electrical protection element in the base of a printed circuit board.

[0013] US Patent 2011 / 0001215A1 discloses a method for applying an electrical component to a suitable substrate.

[0014] Other carrier devices for electrical components are known, for example, from publications DE 10 2012 212 320 A1 or AT 503 718 A2.

[0015] The object of the present invention is to further improve the integration of a protective function or a protective element into an electrical component.

[0016] This problem is solved by a carrier plate having the features of claim 1. Advantageous embodiments of the invention and a method for manufacturing a carrier plate can be found in further claims.

[0017] A carrier plate is proposed that has a mechanically stable base body, similar to those commonly found in known carrier plates. External contacts are provided on the underside of the base body, and connection surfaces for the component are provided on the top side.

[0018] According to the invention, a recess is provided for the placement of an ESD protection element, in which the ESD element is at least partially embedded. The electrical connections of the protection element are accessible from the top or bottom of the base body. In an alternative embodiment, the protection element is electrically contacted at the bottom of the recess. The electrical connection between the protection element and the component can then be made via vias running through the base body. This makes it possible to bring the corresponding connections to the surface of the base body via vias.

[0019] The protective element is mechanically fixed in the recess by means of a connecting device. The fixing can be made at only a few points.

[0020] The protective element is electrically connected to the connection surfaces on the top or the external contacts on the underside of the base body via a structured metallic layer.

[0021] Such a carrier plate has the advantage that the protective element can be embedded in the base body without significant technical effort. The fastener can be selected to serve solely for the mechanical fixation of the protective element in the recess. Preferably, a fastener is chosen that is compatible with subsequent process techniques, particularly for the later mounting of a component onto the connection surfaces, especially by soldering.

[0022] The bonding agent thus functions like an adhesive, passing through a liquid or viscous phase at least once before or during the fixing of the protective element in the recess. The bonding agent does not fill all remaining gaps between the protective element and the outer walls of the recess. It is sufficient to fix the protective element in the recess with the bonding agent, which can be achieved by fastening it at just a few points.

[0023] By at least partially embedding the protective element in the base body, the overall height of the carrier plate is not increased, or only minimally. Furthermore, this allows for flush surfaces between the base body and the protective element, onto which a structured metallic layer can be easily applied for electrical connection between the protective element and the terminals. Such a structured metallic layer can also be easily applied across both surfaces of the base body and the protective element if only a small step height needs to be overcome between them.

[0024] The arrangement of the protective element in the recess has the further advantage that its positioning can be made with a large tolerance and does not require a precise fit. Additionally, by using a suitable, highly thermally conductive material for the base body, a low overall thermal resistance of the combined base body and protective element can be achieved.

[0025] The protective element can be any component designed to dissipate overvoltages. Preferably, the protective element is a varistor, but it can also be a Zener diode, a TVS component, or another non-linear component.

[0026] A varistor is preferred because, firstly, it offers good discharge performance in a relatively small component volume. Secondly, a varistor is inexpensive and can be miniaturized significantly, so that the overall volume of the substrate is not increased, or only minimally increased, by the embedded protective element.

[0027] The bonding agent can be electrically insulating or electrically conductive. It is selected from, or comprises, a plastic, a ceramic material, glass, or metal. Ceramic materials that can be used in paste form and subsequently sintered are preferred. A glass frit is also suitable, as melting the glass allows for the secure fixing of the protective element. A metallic bonding agent can, for example, be a solder with a sufficiently high melting point to withstand the subsequent assembly of the component onto the contact surfaces, or to prevent remelting under these conditions, or, if remelting occurs, to at least be held in position by self-centering (self-alignment through surface tension).However, the bonding agent can also be a plastic, which can be selected to be appropriately temperature- and process-stable, for example an epoxy resin or polyimide.

[0028] Manufacturing is particularly simple if the outward-facing surface of the protective element is flush with a surface of the base body. In this case, the metallic layer can lie flat on both surfaces without any step formation and is therefore particularly easy to apply.

[0029] The protective element can be flush with the top surface of the base body and electrically connected to the terminals on the top surface. However, it is also possible for the protective element to be flush with the bottom surface of the base body and then connected to the external contacts of the base body via the metallic structure layer. Since the external contacts and terminals are electrically connected to each other, at least via vias, connecting the protective element to the external contacts has the same effect as connecting it to the terminals on the top surface of the base body.

[0030] External contacts and connection pads are directly connected via vias. However, it is also possible to provide a multi-layered substrate that has at least one internal metallization layer. This metallization layer can be structured as a wiring layer, in which connections between different connection pads or external contacts are provided. The wiring layer can be designed to connect various components that can be mounted on the surface of the substrate.

[0031] It is also possible to integrate components into the multilayer structure of the base body by structuring the wiring plane accordingly into conductor sections for integrated resistors, metallized areas for integrated capacitors, or, if necessary, curved or spiral conductor sections for the realization of integrated inductors. Individual layers of the multilayer base body can each comprise different dielectrics suitable for the integrated passive components.

[0032] The recess can be arranged arbitrarily on the surface of the carrier plate. Preferably, however, the recess is positioned between the connection surfaces for the component or, even more advantageously, below the connection surfaces for the component. A component to be mounted later, which rests on at least two connection surfaces, is then positioned at least partially above the protective element. This is achieved because the protective element is recessed sufficiently deep into the base body, so that the projection of the protective element above the surface of the base body corresponds at most to the distance of the component above the surface of the base body and thus does not impede the mounting of the component.

[0033] In an advantageous embodiment, the contact surfaces of the carrier plate are formed from the structured metallic layer and can then be applied directly over the protective element and the adjacent surface of the base body. In this way, the protective element does not require an additional surface on the base body, thus eliminating the need for a laterally adjacent arrangement of the protective element and the component, and saving on its footprint.

[0034] The recess is designed to accommodate at least the base area of ​​the protective element. If the base areas of the protective element and the recess are optimally matched, this results in a minimal surface area requirement for both the recess and the protective element. A further advantage of optimal matching is the simple fixing, which, with low tolerances, requires only a few fasteners or connection points.

[0035] However, it is also possible to design the recess in such a way that it can be manufactured with minimal technical effort. For example, the recess can be simply sawn or milled. A groove extending across the entire base body can be created particularly easily by sawing into the base body. While this has a larger surface area than the protective element, it can be produced much more easily and with greater tolerance.

[0036] Regarding mechanical strength, a recess is preferred which is laterally enclosed on four sides by the base body.

[0037] If the depth of the recess is less than the thickness of the base body, the protective element can also rest on the bottom of the recess. However, it is also possible for the recess to extend vertically through the entire base body. Such a recess can be produced by drilling, milling, etching, or thermal treatment, for example, using a laser.

[0038] A carrier plate can be manufactured particularly cost-effectively in sections. For this purpose, the carrier plate has numerous component areas with corresponding connection surfaces and at least one recess each. A protective element is provided in each recess, so that the carrier plate can later be separated into numerous individual carriers, each of which contains a component area for one or more components.

[0039] At least the production of the recess and the application of the metallic structured layer can then be easily integrated for the entire large-area carrier plate. The installation of protective elements is also simplified on a large-area carrier plate.

[0040] To produce a carrier plate according to the invention, a crystalline, ceramic, metallic, or glass substrate is provided. The substrate can also have a layered structure in which different materials are processed for the individual layers.

[0041] In the next step, a recess is created in a surface of the base body to accommodate a protective element. As mentioned, this can be done by drilling, milling, etching, sawing, or thermal material removal. Subsequently, a protective element is at least partially embedded in the recess and mechanically fixed using a fastener. This fixing process may include a thermal step in which the fastener is melted, sintered, or thermally hardened.

[0042] In the next step, a structured metallic layer is created on the surface of the base body and the protective element. This can then be followed by the production of electrical connection surfaces for the component on the top side of the base body.

[0043] The structured metallic layer can be applied in such a way that it overlaps the terminals of the protective element and the connection surfaces on the base body, thereby electrically connecting them. Alternatively, the structured metallic layer is applied over the terminals of the protective element and, either during this process or later, is formed into connection surfaces for the subsequent application of the component.

[0044] According to the invention, after fixing the protective element in the recess and before applying the structured metallic layer, it is ground down from the top side until the top of the protective element is flush with the top of the base body.

[0045] This variant has the advantage that, firstly, the exact depth of the recess is not critical and can even be less than the height of the protective element. Secondly, this variant has the advantage that the protective element can initially be manufactured with a thickness that ensures mechanical stability and safe handling. After being fixed in the recess, the protective element is then mechanically so securely fixed that the loss of stability that would normally be expected from grinding does not occur. The protective element can then be ground down to a height at which it would no longer be manageable or mechanically stable as a single component. This minimizes the volume required for the protective element.The mechanical stability of the base body is also less affected by creating a shallower recess than by a recess required to accommodate a protective element of conventional height. Naturally, this also results in the advantage of a flat and flush surface between the base body and the protective element.

[0046] The structured metallic layer can be easily applied to flush surfaces. According to the invention, creating this layer comprises at least one of the following steps: a) Printing on an electrically conductive material, b) Baking an electrically conductive paste, c) Application of a base metallization from the gas phase, e.g. by vapor deposition or sputtering d) Galvanic strengthening of a base metallization, e) Jet printing of an ink containing electrically conductive particles.

[0047] Printing according to process variant a) can be carried out, for example, by screen printing. The paste can already be electrically conductive and be transformed into the final structured metallic layer by hardening. However, it is also possible to bake the printed mass according to process step b), thereby removing a binder or connecting any electrically conductive particles it may contain by sintering. A coarsely structured metallization can also be finely structured by laser ablation.

[0048] A purely metallic structured layer can include a first step in which a base metallization is applied from the gas phase, as in process step c). This can be reinforced electrochemically or without current, as described in process step d). The structuring can be carried out directly on the base metallization by either removing the base metallization from surface areas not to be metallized. Alternatively, the base metallization and / or, in particular, the subsequent reinforcement can be masked before application, so that the metallic layer is fully structured after the mask is removed.

[0049] The printing application methods described in variants a) and e) result in the desired structuring through the printing process itself. Jet printing is a preferred application method. In this process, fine droplets of an ink containing electrically conductive particles are propelled onto the surface using a suitable printhead. Jet printing can be performed with high structural accuracy, ensuring that the structured metallic layer also exhibits high structural precision. The thickness of the printed layer can be controlled by adjusting the printhead's feed rate. It is also possible to pass the printhead over the surface areas to be coated multiple times, thereby increasing the thickness of the printed layer.

[0050] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying figures. The figures are purely schematic and therefore not to scale. For clarity, individual parts may be omitted from the figures. Identical or functionally equivalent parts are marked with the same reference numerals. Fig. Figure 1 shows a schematic perspective top view of a support plate in which the protective element is arranged in a recess adjacent to the connection surfaces. Fig. Figure 2 shows a carrier plate in a schematic perspective top view, in which a protective element is arranged between two connection surfaces. Fig. Figure 3 shows a schematic perspective top view of a support plate in which the protective element is arranged below the connection surfaces. Fig. Figure 4 shows a basic body with a continuous cutout in perspective view. Fig. Figure 5 shows a schematic perspective top view of a support plate with a protective element arranged in a trench and adjacent to connection surfaces. Fig. Figure 6 shows a support plate with a trench-shaped recess below the connection surfaces. Fig. Figure 7 shows a protective element in perspective view and in cross-section. Fig. Figure 8 shows a protective element in perspective view and in cross-section with opposite Fig. 7 changed orientation. Fig. 9A and Fig. Figure 9B shows the carrier plate in a process stage after the protective element has been fixed in the recess, as it can be obtained in two different process variants. Fig. Figure 10 shows the arrangement after a processing step for planarizing the surface. Fig. Figure 11 shows the arrangement after the application of a structured metallization. Fig. Figure 12 shows a support plate in a schematic top view. Fig. Figure 13 shows a cross-section through a support plate including a schematic perspective view. Fig. Figure 14 shows a carrier plate with a component mounted on it.

[0051] Fig. Figure 1 shows a carrier plate TP according to the invention in a perspective top view. It comprises a base body GK, which is made of a mechanically stable material, in particular a ceramic. The base body GK can be multilayered. On its upper surface, it has contact surfaces AF for a component to be mounted later. On its lower surface, it has external contacts which are connected to the contact surfaces AF via vias (not shown in the figure). An ESD protection element SE is arranged in a recess on the upper surface of the base body and fixed there. The terminals of the protection element SE (not shown in the figure) are electrically connected to the adjacent contact surfaces AF on the base body GK via a structured metallization SM.Depending on the design, with or without internal electrodes, a protective element designed as a varistor can have dimensions of, for example, 466x446x80, 250x250x100, or in the smallest version (Ultra Small) 250x100x80 µm.

[0052] In the illustrated embodiment, the structured metallization SM is implemented as a separate element. However, it is also possible to form the connection surfaces AF and the structured metallization in a single process step from the same metallic layer. It is also possible to first produce the structured metallic layer SM and then the connection surfaces AF.

[0053] The recess that receives the protective element SE is not shown separately here. It is in any case sufficiently large to at least partially receive the protective element SE, so that it is at least partially recessed into the surface of the base body GK. Preferably, the protective element SE is completely embedded in the base body GK.

[0054] Although the protective element SE in the illustrated embodiment of Fig. 1. If the protective element is arranged in a recess on the top surface OS of the base body GK, it can, in a modified version, also be arranged in a recess on the underside of the base body GK. The protective element is then connected to the external contacts on the underside via a structured metallization, which in turn are connected to the terminal surfaces AF on the top surface of the base body GK via vias.

[0055] Fig. Figure 2 shows a further embodiment in which the recess with the protective element SE is arranged between two contact surfaces AF on the top surface of the base body GK. Here too, the contacts of the protective element SE are electrically connected to the contact surfaces AF via a structured metallic layer SM. Again, the structured metallic layer and the contact surfaces AF are applied separately in terms of manufacturing and material, or alternatively, the structured metallic layer forms the contact surface for the subsequent component as a single piece. Here too, it is possible for the top surface of the protective element SE to protrude beyond the top surface of the base body GK, provided the protrusion is small enough that it does not impede the subsequent attachment of a component BE to the contact surfaces AF. If a bump connection is used for this purpose, the protrusion can be up to several tens of micrometers.In an exemplary embodiment, a bump including the connection pad has a total height of approximately 70 µm, so that the protective element could protrude up to a height just below these 70 µm above the surface of the base body.

[0056] Fig. Figure 3 shows a further embodiment in which the recess with the protective element SE is arranged below the connection surfaces AF. In the illustrated embodiment, the protective element SE is oriented transversely to the connection surfaces, but can form any combination of partial or complete overlap without deviating from the invention. In this case, it is clear that the connection surfaces AF can only be created after the protective element has been inserted and fixed in the recess, so that the structured metallic layer is applied over the protective element SE and parts of the base body GK in the form of two or more connection surfaces.

[0057] While the statements according to the Fig. If the recesses AN have 1 to 3 cutouts adapted to the size of the protective element SE, they can also deviate significantly from the size of the protective element SE, e.g. in terms of length, width and depth of the cutout.

[0058] Fig. Figure 4, for example, shows a base body GK with a centrally located recess AN that extends from the top through the base body to the underside of the base body. This design has the advantage that, with sufficient mechanical stability of the base body and sufficient miniaturization of the protective element SE, a space-saving design is achieved. While the recess is shown here with vertical side walls and right-angled edges, it can also have sloping side walls and rounded or otherwise shaped corners.

[0059] Fig. Figure 5 shows a further embodiment in which a particularly simple method can be used to produce the recess AN. Here, the recess AN is designed as a trench extending across the base body GK with a uniform width and depth. Such a trench, or such a trench-shaped recess AN, can be easily produced using a milling machine or a saw blade. A saw blade can also be used to easily create rectangular trench cross-sections adapted to the outer dimensions of the protective element SE. The protective element itself does not extend over the entire length of the trench, but is instead aligned with the connection surfaces AF, to which it is electrically connected via a structured metallic layer SM. Here, too, the structured metallic layer SM and the connection surfaces AF can be made of the same material or of a single, uniform layer.

[0060] The embodiment according to Fig. 6 differs from the version according to Fig. 5 only by the fact that the trench-shaped recess AN passes under the connection surfaces AF. In this embodiment, it is advantageous if the surface of the protective element is flush with the surface of the base body GK, since the connection surfaces AF must subsequently be applied over both surfaces.

[0061] The protective element SE is depicted in the described figures as a rather flat element with a relatively low height. According to the invention, this element can also be embedded in the base body in orientations other than those shown and, for example, be oriented vertically so that it is perpendicular to the surface.

[0062] Fig. Figure 7 shows a schematic perspective view of a protective element SE, which is designed, for example, as a varistor. The varistor protective element SE has a multilayer structure in which layers of varistor ceramic are arranged between structured metal layers ME, which serve as electrode layers. The metal layers ME are alternately connected to electrical terminals A and B, which are brought to a surface of the protective element SE.

[0063] In the illustrated embodiment, the metal planes ME are arranged vertically, and the contacts are located on the side of the protective element SE where the metal planes intersect the surface. The right side of the illustration shows two electrode planes in a top view. The metal planes can be structured so that they intersect the surface of the protective element SE near one edge and are connected there to contact A, while on the same surface near the opposite edge, only metal planes intersect the surface, which are connected to contact B. This facilitates the contacting of the two-pole component. However, the electrical connections of the protective element SE can also be connected to the metal planes ME in other ways.

[0064] Fig. Figure 8 shows an arrangement of a multi-layered protective element SE, for example a varistor, in which the metal layers ME run transversely to the surface with the terminals A and B and, in the subsequent mounting in the base body GK, are aligned parallel to the surface of the carrier plate. In the right part of the Fig. Figure 8 again shows a cross-section through the protective element SE and the metal planes ME. The figure makes it clear that the metal planes ME are alternately connected by a type of via or common contact, which connects all connected metal planes ME to a terminal A, B on the top side of the protective element SE.

[0065] Fig. Figure 9A shows an embodiment of the invention by means of a schematic cross-section through a carrier plate during a manufacturing process step. The base body GK of the carrier plate is already provided with vias DK, which connect an upper opening on the top side with a lower opening on the underside of the base body GK. External contacts AK can be applied over the vias on the underside as early as an early process step.

[0066] A recess AN is created in the top surface of the base body GK, having a cross-section that is arbitrary but preferably corresponds to the outer dimensions of the protective element SE. Using a fastener VM, a protective element SE is then positioned in the recess AN such that it does not protrude, or only minimally protrudes, beyond the surface of the base body GK. A fastener VM inserted into the recess AN, for example, is displaced when the protective element SE is inserted and can protrude upwards from the joint, forming a bead as shown in the figure.

[0067] Fig. Figure 9B shows a corresponding arrangement in which the protective element SE is embedded deeper in the recess AN, but remnants of fasteners VM protrude above the surface of the base body GK. Such a configuration is also obtained if the protective element SE is fixed in the recess AN at only a few points with fasteners and the remaining gaps are subsequently filled with fasteners.

[0068] In the next step, a flat surface is created using a material removal process, which is described in the Fig. Figure 9, indicated by arrows, shows that the surface is mechanically processed and planarized. This can be achieved through purely mechanical grinding or chemically assisted mechanical polishing (CMP). Alternatively, the surface can also be milled flat.

[0069] Fig. Figure 10 shows the arrangement after such planarization of the surface, in which the top of the protective element SE is flush with the top of the base body GK, and in which the connecting element does not protrude or bulge beyond the joint between the protective element SE and the base body.

[0070] After applying the bonding agent VM, which is advantageously used in pasty or liquid form, a hardening process can then be carried out or actively performed in order to ensure, firstly, the mechanical fixation of the protective element SE in the base body and, secondly, to convert the formerly liquid or pasty bonding agent VM into a hardened state that is sufficiently stable in relation to subsequent process steps for further processing and, in particular, for the application of contact surfaces and the soldering of components.

[0071] In the next step, a structured metallic layer SM is applied to the top surfaces of the base body and the protective element SE. This layer is structured to connect the subsequent connection surfaces AF of the carrier plate to the electrical connections of the protective element SE. Since the protective element SE is typically two-pole and the associated connection surfaces AF are also present in even numbers, each connection of the protective element SE can be connected to a connection surface AF using the structured metallic layer SM. Alternatively, the structured metallic layer SM can be designed to form a connection surface that contacts each connection of the protective element SE. Such a design is used, for example, in the Fig. 11 shown.

[0072] The structured metallic layer SM can be produced in the form of an electrically conductive paste, which can be directly transformed into a highly conductive electrode layer by baking. It is also possible to apply metallic particles in the smallest possible form and transform them into a continuous metal layer by heating. This method has the advantage that the melting can take place at significantly lower temperatures, far below the actual melting point of the metallic layer. The metallic particles are transformed into a material or layer that can only be remelted at a much higher temperature and therefore remains stable even at higher temperatures.

[0073] It is also possible to form the structured metallic layer (SM) from a base metallization applied via the gas phase, which is then reinforced with an electrically conductive metal using an electroplating or electroless process. For example, it is possible to sputter and structure thin layers of gold, platinum, titanium, chromium, copper, nickel, silver, or another metal. Structuring can be achieved by etching or laser ablation of the areas not to be coated. Alternatively, a mask can be applied to the areas not to be coated. This mask can be applied and structured before the base metallization is created, or only after the base metallization has been created.

[0074] After electroplating or electroless strengthening of the base metallization, which leads to a thickening of the structured metallic layer SM, the mask, along with the overlying (lift-off process) or underlying base metallization, can be removed, thus obtaining a desired structure, for example, in the form of contact surfaces and connecting conductors to the terminals of the protective element SE. Any conductive metal, such as copper, nickel, gold, or palladium, can be used for electroless strengthening.

[0075] Fig. Figure 12 shows a schematic top view of a carrier plate where the connection surfaces AF partially overlap the protective element SE, which is located below the connection surfaces AF. The overlap simultaneously establishes electrical contact with the terminals of the protective element.

[0076] The dashed line indicates the base area of ​​a metallization layer ME of the protective element SE connected to terminal B. The metallization layers are connected alternately to terminals A and B of the protective element SE.

[0077] Fig. Figure 13 shows a combined representation of a cross-section through a carrier plate at a process stage during the manufacture according to Fig. Figure 10, where the cross-section is extended in perspective to a three-dimensional representation. The section is drawn through the base body GK, the vias DK, the protective element SE, and the connection contacts AK. The electrical connections A and B of the protective element SE are only indicated in the perspective view. The vias DK electrically connect the external contacts AK on the underside to the top side, where they are in turn contacted with the connection surfaces AF in a later process step not yet shown. After the application of a structured metallic layer, each of the connections A and B of the protective element SE is connected to one of the two vias DK, each corresponding to a connection surface. The external contacts AK provide the electrical connection on the underside for the connection surfaces AF and B located on the top side.for protective element SE and the component to be mounted later on the connection surfaces AF.

[0078] Fig. Figure 14 shows a schematic cross-section of a carrier plate on which an electrical component BE is mounted on the contact surfaces AF, which can be formed from the structured metallic layer SM. A bump connection, for example, can be used as the electrically conductive connection between the terminals of the component and the contact surface AF of the carrier plate. It is also possible to solder the component BE directly as an SMD component or to contact it using an electrically conductive adhesive.

[0079] Component BE, for example, is an LED mounted on the surface of a ceramic substrate. A varistor, acting as a protective element SE, is embedded within this substrate and connected to the terminals AF. The protective element SE is connected in parallel to the terminals of component BE and the LED, thus protecting the LED against high current surges, such as those that can occur during electrostatic discharge (ESD). The protective element SE can safely dissipate current spikes, either current- or voltage-dependent, by creating a short circuit, preventing damage to component BE or the LED from overvoltage.

[0080] Since the invention could only be illustrated by means of a limited number of embodiments and figures, it is not limited to the embodiments shown. In particular, the recess can be arranged arbitrarily on the top or bottom of the base body GK or even extend through the entire base body. The recess can extend to any depth within the base body and is preferably dimensioned such that the mechanical stability of the base body is not impaired. The number of connection surfaces AF is preferably two, but can also be greater. Several connection surfaces can be connected to the same connection of the protective element. Connection surfaces for more than one component can also be provided and connected to the same protective element.

[0081] The structured metallic layer can be formed from any electrically conductive metal-containing material and can be configured as the sole connection to the terminal surface, as a combined connection and terminal surface, or solely as a terminal surface in direct contact with the terminals of the protective element.

[0082] The number of vias DK corresponds at least to the number of connection surfaces provided and connected to the protective element SE, but is preferably chosen to be larger in order to ensure a low-loss or lossless electrical connection between the top and bottom of the carrier plate.

[0083] The protective element can be precisely embedded in the recess and completely fill the joint using the VM fastener. However, it is also possible to fix the SE protective element at only a few points. The remaining gap can then be filled in a later processing step with any suitable filler material, particularly an insulating material or, for example, a moldable compound. This can be used during the subsequent encapsulation of a component according to [relevant standard / guideline]. Fig. 14 or even before the application of the connection surface or the soldering of the component.

[0084] The base body can be cuboid and flat. It can have several component areas, of which only one is shown in each figure, corresponding exactly to a support for a component BE. However, a single support can also carry multiple components BE or have connection surfaces for multiple components. A protective element can be provided for each component. It is also possible to connect several components in parallel with a single protective element. Reference symbol list A, B connections of the protective element AF connection surfaces on OS of the GK AK External Contacts on US of the GK AN exception BE electrical component BU Bump DK through-hole plating GK basic body with ME Wiring level / Metallization level / Metal layer OS top of the GK SE protective element SM structured metallic layer TP carrier plate, possibly separable into carrier US underside of the GK VM fasteners

Claims

[1] Carrier plate (TP) for an electrical component (BE) - with a mechanically stable base body (GK) which has external contacts (AK) on a bottom side (US) and connection surfaces (AF) for the component (BE) on a top side (OS), - with a recess (AN) in which an ESD protection element (SE) discrete from the base body (GK) is at least partially embedded, wherein the electrical connections of the protection element (SE) are accessible from the top (OS) or the bottom (US) of the base body (GK), - in which the protective element (SE) is mechanically firmly embedded in the recess (AN) of the base body (GK) by means of a connecting element (VM), wherein the connecting element (VM) does not fill all the spaces between the protective element (SE) and the outer walls of the recess (AN), - in which the electrical connections of the protective element (SE) are connected via a structured metallic layer (SM) to the contact surfaces (AF) on the top (OS) or the external contacts (AK) on the bottom (US). [2] Carrier plate (TP) according to claim 1, wherein the protective element (SE) is fastened in the recess (AN) at only a few points. [3] Carrier plate (TP) according to one of the preceding claims, wherein the recess (AN) has a cross-section corresponding to the outer dimensions of the protective element (SE). [4] Carrier plate (TP) according to one of the preceding claims, wherein the recess (AN) is provided in the underside (US) of the base body (GK) and the protective element (SE) is flush with the underside (US). [5] Carrier plate (TP) according to one of the preceding claims, wherein the external contacts (AK) and the connection surfaces (AF) are electrically connected via vias (DK). [6] Carrier plate (TP) according to one of the preceding claims, wherein the recess (AN) extends under the connection surfaces (AF). [7] Carrier plate (TP) according to any of the preceding claims, wherein the base body (GK) is crystalline, ceramic, metallic or glassy. [8] Carrier plate (TP) according to one of the preceding claims, wherein the depth of the recess is less than the thickness of the base body. [9] Carrier plate (TP) according to any of the preceding claims, wherein the protection element (SE) is a varistor, a Zener diode, a TVS device or another non-linear element. [10] Carrier plate (TP) according to any of the preceding claims, wherein the connecting element (VM) comprises a plastic or ceramic material, glass or a metal. [11] Carrier plate (TP) according to any of the preceding claims, wherein the connecting means (VM) comprises a ceramic material, glass or a metal. [12] Carrier plate (TP) according to claim 11, wherein the connecting element (VM) is a ceramic material, glass or a metal. [13] Carrier plate (TP) according to one of the preceding claims, wherein an outwardly facing surface of the protective element (SE) is flush with a surface of the base body (GK), and wherein the structured metallic layer (SM) rests on the two flush surfaces. [14] Carrier plate (TP) according to one of the preceding claims, wherein the base body (GK) has a multi-layer structure and a wiring level (SM) is provided inside the base body (GK). [15] Carrier plate (TP) according to any of the preceding claims, where the recess (AN) is located between or below the connection surfaces (AF) for the component (BE), where the protective element (SE) is recessed so deeply into the base body (GK) that the component (BE) can be applied at least partially over the protective element (SE). [16] Carrier plate (TP) according to one of the preceding claims, wherein the recess (AN) is formed in the form of a trench which extends transversely over the base body (GK). [17] Carrier plate (TP) according to one of claims 1 to 15, wherein the recess (AN) is enclosed laterally by the base body (GK), and wherein the recess (AN) extends vertically through the entire base body (GK). [18] Carrier plate (TP) according to one of the preceding claims, on which a plurality of component areas with connection surfaces (AF) and at least one recess (AN) are provided, wherein the carrier plate (TP) can be divided into individual carriers, on which each component area for one or more components (BE) is provided. [19] Method for producing a carrier plate (TP) for a component (BE), - in which a crystalline, ceramic, metallic or glass substrate (GK) is provided, - in which a recess (AN) for receiving a protective element (SE) is created in a surface of the base body (GK), - in which a protective element (SE) discrete to the base body (GK) is at least partially arranged in the recess (AN) and mechanically fixed by means of a connecting element (VM), wherein the connecting element (VM) does not fill all the spaces between the protective element (SE) and the outer walls of the recess (AN), - in which the protective element (SE) is ground down from a top side after being fixed in the recess (AN) and before applying a structured metallic layer (SM) until the top side of the protective element (SE) is flush with the top side (OS) of the base body (GK), - in which a structured metallic layer (SM) is created on the surface of the base body (GK) and the protective element (SE), - in which electrical connection surfaces (AF) for the component (BE) are formed on the top surface (OS) of the base body (GK), - in which the structured metallic layer (SM) overlaps with electrical connections of the protective element (SE) and the connection surfaces (AF) and electrically connects them, or in which the structured metallic layer (SM) forms the connection surfaces (AF) and is structured in such a way that it overlaps one of the electrical connections of the protective element (SE) in each case. [20] Method according to the preceding claim, wherein the protective element (SE) is fastened in the recess (AN) only at a few points. [21] Method according to claim 19 or claim 20, wherein the connecting element (VM) comprises a ceramic material, glass or a metal. [22] Method according to any one of claims 19 to 21, wherein the recess (AN) is produced by sawing into the base body (GK), milling, etching or laser drilling. [23] Method according to any one of claims 19 to 22, wherein the production of the structured metallic layer (SM) comprises at least one of the following steps: - Printing on an electrically conductive material, - Baking in an electrically conductive paste, - Application of a base metallization from the gas phase and galvanic reinforcement of the base metallization or by sputtering or vapor deposition, - Jet printing with an ink containing electrically conductive particles. [24] Method according to any one of claims 19 to 23, wherein the recess (AN) has a cross-section corresponding to the outer dimensions of the protective element (SE).

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