Preform for a magneto-semiconductor assembly and method for its manufacture

Abstract

Method for producing preforms for magneto-semiconductor assemblies (100), wherein the method comprises: • Forming a plurality of permanently magnetizable elements (102, 202, 282, 292, 302) on a planar support structure (101, 201, 293, 301, 322) in a sensor-free area of ​​the support structure (101, 201, 293, 301, 322) before a semiconductor chip (121, 331) or sensor is arranged or placed on the support structure (101, 201, 293, 301, 322); • wherein the formation is carried out by applying a permanently magnetizable forming material to the support structure (101, 201, 293, 301, 322); • wherein a preform (111, 211, 281, 291, 311, 321) has a flat bottom of a recess (104, 204, 283, 294) for placing the semiconductor chip (121, 331) or the sensor; • wherein, in at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302), a section 103, 203, 303 of the permanently magnetizable mold material extends through the support structure (101, 201, 293, 301, 322) and forms an undercut section 103, 203, 303 which fixes the permanently magnetizable elements (102, 202, 282, 292, 302) to the support structure (101, 201, 293, 301, 322) and forms a rib which at least partially encloses the flat base.

Description

Background of the inventionField of the invention

[0001] The present invention relates to a preform for a magnetic semiconductor assembly and methods for producing such a preform. Description of the state of the art

[0002] A variety of semiconductor devices and their packages are known in the art. Some of these semiconductor devices include a package defining a cavity, a magnetic sensor chip formed within the cavity, and molding material covering the magnetic sensor chip and substantially filling the cavity. Such semiconductor devices include motors, speakers, microphones, and magnetic sensors used in automotive technology. All of these devices include permanent magnets bonded to support substrates by adhesives or screwing techniques. Sensors of these devices, such as reverse-bias magnetic sensors, are bonded to the back of the support structure.

[0003] Nevertheless, there remains potential room for improving the fabrication of semiconductor devices that include magnetic structures or magnetizable elements.

[0004] The subsequently published EP 4 102 187 A1 relates to an integrated magnetic field sensor circuit with integral ferromagnetic material.

[0005] DE 10 2005 038 293 A1 relates to a magnetic sensor device having components mounted on a magnet.

[0006] DE 10 2012 110 492 A1 relates to a magnetic sensor component.

[0007] DE 10 2008 058 895 A1 relates to an integrated circuit comprising a sensor with injection-molded magnetic material.

[0008] US 6 200 828 B1 relates to an integrated circuit package architecture with a variably specified interconnect and a method for manufacturing the same. US 2010 / 0 295 140 A1 relates to a semiconductor device.

[0009] US 6 265 865 B1 relates to a magnetic field sensor with an integrated circuit comprising a magnet.

[0010] US 6 933 716 B2 a sensor package with minimized cross-section.

[0011] US 2009 / 0 072 334 A1 relates to a semiconductor device, a preform package and a method for producing the same.

[0012] US 4 971 930 A relates to an EPROM semiconductor device.

[0013] US 5 200 367 A relates to a method for assembling a package of semiconductor elements.

[0014] US 2009 / 0 191 421 A1 concerns a soft magnetic powder composite material.

[0015] US 8 058 870 B2 relates to a method for manufacturing a magnetic sensor.

[0016] US 5 912 556 A concerns a magnetic sensor with a chip.

[0017] US 5 472 539 A relates to a method for forming and positioning a moldable permanent magnet on electromagnetically actuated microcomponents. Summary of the invention

[0018] There may be a need to provide preforms for a magnet semiconductor assembly group and methods for manufacturing such preforms that are simple to implement and enable high yield of magnetic semiconductor assemblies.

[0019] The claimed invention is defined by the independent claims.

[0020] According to an exemplary aspect, a method for producing pre-molds for a magnetic semiconductor assembly is provided, the method comprising forming a plurality of permanently magnetizable elements on a carrier structure in a sensor-free region of the carrier structure by applying permanently magnetizable molding material to the carrier structure.

[0021] According to a further exemplary aspect, a pre-mold array for magnetic semiconductor assemblies is provided, wherein the preform comprises a carrier structure and a plurality of permanently magnetizable elements made of a permanently magnetizable material formed on the carrier structure by an adhesive-free process, wherein the plurality of permanently magnetizable elements are formed in a sensor-free region of the carrier structure.

[0022] According to an exemplary aspect, a method for producing pre-molds for a magnetic semiconductor assembly is provided, the method comprising forming a plurality of permanently magnetizable elements from permanently magnetizable molding material on a support structure, placing a semiconductor chip on one of the plurality of permanently magnetizable elements from a permanently magnetizable material.

[0023] The use of a method for producing a preform for a magnetic semiconductor assembly may enable a simple and efficient method for producing a preform. In particular, it may be possible to reduce the restriction with regard to processing or formation conditions during the formation of the permanently magnetizable elements by applying permanently magnetizable material, since the permanently magnetizable elements are formed before a semiconductor chip or sensor is arranged or placed on the carrier structure. Furthermore, the provision of a preform or a plurality of preforms that already have permanently magnetizable elements made of permanently magnetizable material may enable simplified further processing of the preform(s) or production of a magnetic semiconductor assembly, since the respective semiconductors or sensors can be easily incorporated afterwards.In addition, the yield of magnetic semiconductor assemblies may be increased because the manufactured preforms are visually inspected and only good or defect-free permanently magnetizable elements may be assembled with semiconductors, thus saving semiconductors. Brief description of the drawings

[0024] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and which form a part of the specification, illustrate embodiments of the invention.

[0025] In the drawings: show the Fig. 1A - 1I Magnetic semiconductor assemblies in various stages of manufacture according to an embodiment. shows Fig. 2A is a schematic representation of an example of the shape of a preform according to an embodiment. shows Fig. 2B is a schematic representation of an example of the shape of a preform according to another embodiment. shows Fig. 2C is a schematic representation of an example of the shape of a preform according to yet another embodiment. shows Fig. 3A is a schematic diagram of an example of a carrier structure and a semiconductor that may be used in a magnetic semiconductor assembly. shows Fig. 3B is a schematic diagram of another example of a carrier structure and a semiconductor that may be used in a magnetic semiconductor assembly. shows Fig. 3C is a schematic representation of yet another example of a carrier structure and a semiconductor that may be used in a magnetic semiconductor assembly. shows Fig. 3D a schematic representation of yet another example of a carrier structure and a semiconductor that can be used in a magnetic semiconductor assembly. Description of further embodiments

[0026] Further embodiments of the method and of the preform array, as well as of a magnetic semiconductor assembly, are explained below. It should be noted that embodiments described in the context of the method can also be combined with embodiments of the preform array and with embodiments of the semiconductor assembly, and vice versa.

[0027] According to another exemplary aspect, a preform array is provided, wherein the preform array is manufactured according to a method according to an embodiment.

[0028] In particular, the application of the permanently magnetizable molding material may be a direct application, i.e., an application in which the molding material is applied to the carrier substrate in a liquid, fluid, or at least plastic state and not in a solidified state. For example, the carrier structure may be a leadframe, a circuit board, a printed circuit board, or flexible printing material. For example, the carrier structure may be an electrically conductive carrier structure, e.g., an electrically conductive leadframe.

[0029] The forming process may be any process in which the shape or form of the element, e.g., the shape of the permanently magnetizable element, is created or manufactured during the forming process. Examples of a forming process may be a forming process suitable for achieving a permanently magnetizable element from a permanently magnetizable material, e.g., a forming or forming process using a mold, or a forming or forming process carried out by simply extruding the molding material onto the carrier substrate without using a specific mold. For example, an injection molding process, such as a thermoplastic or thermoset injection molding process, may be used. In particular, the forming of the plurality of magnetizable elements may be a direct formation on the carrier, e.g.,The permanently magnetizable elements can be formed on the carrier substrate without adhesives. Thus, it may be necessary to distinguish between direct formation and the indirect arrangement or placement of already formed permanently magnetizable elements on a carrier, which are then subsequently fixed to the carrier, for example, using adhesives.

[0030] It should be noted that the permanently magnetizable elements may take on any desired shape or form, e.g., the shape may correspond to a cuboid, a cube, a truncated pyramid, which may be solid or have at least one geometric feature, such as a hole, a recess, a depression, a notch, or the like. In particular, each of the permanently magnetizable elements formed from a permanently magnetizable material may be adapted to accommodate a semiconductor chip or sensor. For example, each of the plurality of permanently magnetizable elements may form a main body from one or a single preform or at least a portion of the main body. In particular, the permanently magnetizable elements may be formed in a sensor-free or semiconductor-free region of the support structure.

[0031] According to a further exemplary aspect, a method for manufacturing magnetic semiconductor assemblies is provided, the method comprising forming a plurality of magnetic elements as preform structures on a carrier structure in a semiconductor chip-free region of the carrier structure by applying a magnetic molding material to the carrier structure and subsequently arranging a plurality of semiconductor chips on the carrier structure, each of which is positioned on an assigned element from the plurality of magnetic elements, to thereby form the magnetic semiconductor assemblies. In this context, the term "magnetic element" may in particular refer to an element that is magnetizable or one that is already magnetized.

[0032] The term "molding" or "molding process" may in particular refer to any process by which the shape or form of the element, e.g. the shape of the permanently magnetizable element, is created or produced during the forming process, e.g. during a molding or a molding process.

[0033] The term “sensor-free region” may, in particular, refer to a specific region of a support structure on or in which no sensor is located. For example, the region may be defined with respect to a plan view of a planar or quasi-two-dimensional support structure. It should be noted that this definition of the term “sensor-free region” particularly covers the case where opposite main surfaces of a support structure in the corresponding region are sensor-free. In other words, a sensor-free region of a support structure may be a region in which no sensors are arranged above or below the support structure. However, the corresponding region may be adapted, suitable, or intended for the subsequent arrangement of a sensor on this region.For example, after forming or molding a permanently magnetizable element from a permanently magnetizable material, a sensor of an assembly may be arranged or formed in the formerly sensor-free region above or below the formed permanently magnetizable element or connected thereto. The term "semiconductor-free region" may, in particular, refer to a specific region of a carrier structure on or in which no semiconductor is located.

[0034] The term "preform" or "preform package" may specifically refer to a unit or element comprising a shaped, permanently magnetizable element or package that may be adapted to receive a semiconductor, semiconductor chip, integrated circuit chip, or sensor, but does not yet include the semiconductor, semiconductor chip, integrated circuit chip, or sensor. Thus, the preform may be said to form a type of enclosure that is preformed and subsequently used to house a semiconductor, semiconductor chip, integrated circuit chip, or sensor.

[0035] The term "assembly" may, in particular, refer to a group of components or permanently magnetizable elements that are assembled or connected to one another to form a device or system adapted to perform a specific function or process, e.g., a so-called microelectromechanical system (MEMS). The specific term "magnetic semiconductor assembly" may, in particular, refer to an assembly comprising at least one magnet or one permanently magnetizable element and at least one semiconductor, such as an IC chip or a sensor. Examples of such a magnetic semiconductor assembly may be a MEMS Hall sensor or a MEMS microphone.

[0036] The term "permanently magnetizable" may in particular refer to the property of any material that this material can be permanently magnetized by excitation or stimulation by an external field. In other words, the term "permanently magnetizable" may refer to the property of a material that this material exhibits remanence or residual magnetism after excitation. Thus, material that is only paramagnetic may not fall under the definition of "permanently magnetizable". In particular, the permanently magnetizable material may be a material made of a single compound, or it may be a material that has two or more compounds, for example, a main compound, which may be malleable, and a marker or filler compound from which the magnetizing effect emanates.For example, the permanently magnetizable material may comprise or be a ferromagnetic material such as iron, nickel or cobalt or a corresponding alloy, or it may be a plastic material that may form a permanent magnet.

[0037] The term "permanently magnetizable element" or "permanently magnetizable element structure" may, in particular, encompass any structure comprising one (in particular more than one) material and having a specific shape. For example, the permanently magnetizable element may comprise or be formed from a mixture of two compounds, e.g., a moldable main compound into which a permanently magnetizable filler or marking compound is mixed. In particular, the permanently magnetizable element may be a composite or a composite structure comprising at least one permanently magnetizable compound.

[0038] The term "molding material" may, in particular, refer to a material suitable for being formed in a molding or casting process. In particular, a molding material may be viscous, plastic, or liquid in order to be molded or cast.

[0039] According to an embodiment of the method, at least one of the plurality of permanently magnetizable elements is a three-dimensional element, wherein the extension of the element in one dimension is in the range between 2.5 mm and 25 mm, in a second dimension is in the range between 2.5 mm and 25 mm, and in a third dimension is in the range between 2.5 mm and 25 mm.

[0040] In particular, the extension of the element in one dimension is in the range between 5.0 mm and 15 mm, in a second dimension in the range between 5.0 mm and 15 mm, and in a third dimension in the range between 5.0 mm and 15 mm. For example, a permanently magnetizable element may have a size of at least 5 mm x 5 mm x 5 mm. Preferably, the size of the at least one permanently magnetizable element may be 7 mm x 7 mm x 7 mm. In particular, all elements from the plurality of magnetizable elements made of a magnetizable material may have the same or substantially the same size. For example, the size of at least one of the plurality of permanently magnetizable elements may be adapted to accommodate sensors of a specific size.The provision of such relatively large permanently magnetizable elements made of a permanently magnetizable material may make it possible to provide magnets or magnetic bodies that generate a relatively strong magnetic field. For example, the remanence or remanent magnetization may be in the range of 100 mT to 1000 mT, in particular in the range of 250 mT to 600 mT. However, a lower or higher remanence may also be possible, depending on the permanently magnetizable material and / or the size of the permanently magnetizable elements. Furthermore, it may be possible to arrange or place a relatively large semiconductor or sensor near the permanently magnetizable elements.

[0041] According to one embodiment of the method, the permanently magnetizable material comprises electrically conductive material.

[0042] In particular, the specific electrical conductivity of the conductive material may be above a certain limit, in particular it may be above 1·10 5 S / m or even over 1·10 6 S / m. The use of an electrically conductive material may enable simple and efficient conduction or connection of a sensor placed on these permanently magnetizable elements.

[0043] According to one embodiment, the method further comprises forming an electrically insulating layer between the carrier structure and at least one of the plurality of permanently magnetizable elements made of a permanently magnetizable material.

[0044] For example, the electrically insulating layer or an insulating structure may be formed on the carrier substrate before the permanently magnetizable elements are formed on the carrier substrate.

[0045] In particular, several or all of the plurality of permanently magnetizable elements can be electrically insulated from the support structure by providing insulating layers or structures. This may ensure that no short circuit is generated or formed between the permanently magnetizable elements and the support structure.

[0046] According to one embodiment, the method further comprises singulating the plurality of permanently magnetizable elements.

[0047] According to one embodiment, the method further comprises magnetizing at least one of the plurality of permanently magnetizable elements.

[0048] In particular, magnetization may occur before or after the separation of the plurality of permanently magnetizable elements. If it occurs before, it may be easy to apply the same magnetization to all permanently magnetizable elements. If it occurs afterward, this may allow the separated permanently magnetizable elements to be subjected to different magnetizations. Due to the magnetization or magnetization process, the permanently magnetizable elements become magnetized elements, i.e., elements with a permanent magnetization or a remanent magnetization.

[0049] According to one embodiment of the method, at least one of the plurality of permanently magnetizable elements made of a permanently magnetizable material has a recess.

[0050] In particular, the recess may be formed on the upper side of the carrier. The recess may have a shape or form adapted to generate or achieve a desired magnetic field at or near the permanently magnetizable or magnetized element. In addition, the recess may be used to insert or arrange a semiconductor, semiconductor chip, IC chip, or sensor into the recess. It should be noted that the term "recess" in particular does not only refer to an area or cavity free of material, but may also be interpreted more broadly, namely in the sense that no permanently magnetizable material is present in the recess, but other material may be present. Thus, the term "recess" may refer to empty recesses or recesses filled with material, as long as the material filling the recess is not permanently magnetizable and / or non-magnetic.For example, the recess or a part of the recess may have a cuboid, cylindrical or pyramidal shape or form.

[0051] According to one embodiment of the method, at least one of the plurality of permanently magnetizable elements has a hole.

[0052] In particular, the hole may be a blind or through hole and / or have a circular or elliptical cross-section. Thus, the permanently magnetizable element made of a permanently magnetizable material may form a type of hollow cylinder. Such a hollow cylinder may be suitable for forming a magnetic field that is zero or close to zero in the recess, blind hole, or through hole.

[0053] According to one embodiment of the method, at least one of the plurality of permanently magnetizable elements is formed on a first main surface of the support structure and has a portion that extends through the support structure to a second, opposite main surface of the support structure.

[0054] According to one embodiment, the method further comprises arranging at least one semiconductor chip on the plurality of permanently magnetizable elements made of a permanently magnetizable material.

[0055] In particular, the at least one semiconductor chip or IC chip may form a sensor or a sensor module or be part of such, or even form the sensor. For example, a sensor or sensor chip is arranged. After the IC chip or semiconductor chip has been arranged, attached or placed on the permanently magnetizable element, e.g. on a flat upper side or in a recess, the IC chip or semiconductor chip may be electrically connected to contacts, contact points or terminals of the carrier structure or an external structure. The electrical connection may be formed, for example, by wire bonding. In particular, the at least one semiconductor chip may be arranged or placed on a side of the carrier structure opposite the permanently magnetizable element.For example, the permanently magnetizable element may be formed or shaped on a first main surface of the carrier substrate, and the at least one semiconductor chip may then be arranged on a second main surface opposite the first main surface. In particular, the arranged semiconductor chip may be surrounded by a portion of a permanently magnetizable element, e.g., surrounded along the circumference. For example, a portion of the permanently magnetizable element may extend through the carrier structure and form a peripheral structure surrounding the arranged semiconductor chip.

[0056] In particular, the one or more semiconductor chips may be sensors or semiconductor chips without a package, or they may be part of a sensor or sensor module already contained in a package.

[0057] According to one embodiment, the method further comprises encapsulating the at least one semiconductor chip or IC chip arranged on the plurality of permanently magnetizable elements.

[0058] For example, encapsulation may be performed by molding or casting a resin or a similar pourable or viscous compound. In particular, at least one of the plurality of permanently magnetizable elements, several of the plurality of permanently magnetizable elements, or all of the plurality of permanently magnetizable elements may be encapsulated.

[0059] According to one embodiment of the preform array or the preform set, each of the plurality of permanently magnetizable elements is a three-dimensional element, wherein the extension of the element in one dimension is in the range between 2.5 mm and 25 mm, in a second dimension is in the range between 2.5 mm and 25 mm, and in a third dimension is in the range between 2.5 mm and 25 mm.

[0060] In particular, the dimension of the element in one dimension is in the range between 5.0 mm and 15 mm, in a second dimension in the range between 5.0 mm and 15 mm, and in a third dimension in the range between 5.0 mm and 15 mm. For example, the permanently magnetizable element may have a size of at least 5 mm x 5 mm x 5 mm.

[0061] According to one embodiment of the preform array or the preform set, the support structure is an electrically conductive support structure.

[0062] According to one embodiment of the preform array or the preform set, the permanently magnetizable material is an electrically conductive material.

[0063] Alternatively, the permanently magnetizable material may be an electrically insulating material.

[0064] According to one embodiment, the preform array or preform set further comprises an electrically insulating layer arranged between the electrically conductive support structure and each of the plurality of permanently magnetizable elements made of permanently magnetizable material.

[0065] According to one embodiment of the preform array or the preform set, the permanently magnetizable material is electrically conductive.

[0066] According to one embodiment of the preform array or the preform set, the permanently magnetizable material is electrically insulating.

[0067] In particular, the permanently magnetizable material may be a plastic or synthetic material. For example, polyphenylene sulfide (PPS) or a similar material may be used as the permanently magnetizable material. PPS may be a suitable material because it is permanently magnetizable and temperature-stable up to temperatures exceeding 200 °C, allowing subsequent wire bonding of the preform or preform housing without destroying or reducing the permanently magnetizable elements or the magnetism of the magnetized elements.

[0068] According to one embodiment of the preform array or the preform set, at least one of the plurality of permanently magnetizable elements has an undercut engaging behind the carrier structure.

[0069] The term "undercut" or "back taper" may in particular refer to a structure or a permanently magnetizable element of a structure that engages behind or engages with another structure or surrounds it. Thus, the structure may not subsequently be easily removed or detached from the other structure. In particular, no glue or adhesive may be necessary when such an undercut or back taper is used. Such an undercut or undercut structure may, for example, be manufactured or formed when a moldable or molding material is molded through a hole or slot of a carrier or the carrier structure and the moldable material spreads out behind the hole or slot.

[0070] In summary, one embodiment can essentially be seen in the fact that a preform or a preform array and a method for its production or manufacturing are provided, wherein the preform comprises a permanently magnetizable or even magnetized element made of a permanently magnetizable material, which is formed on a carrier structure, while semiconductors or sensors that will subsequently utilize the magnetic field generated by the magnetized element are not yet connected to the preform. The carrier structure, which comprises the permanently magnetizable elements, may then be further processed by magnetization before or after dicing and / or placing semiconductor chips or IC chips has taken place.In particular, a preform having a magnetic cavity and forming a permanently magnetizable element from a magnetic cavity housing may be provided, which may be used to package semiconductor or silicon bare chips or pre-packaged sensors. The permanently magnetizable elements made of a permanently magnetizable material can provide large reverse bias magnets for magnetic semiconductor assemblies, both in terms of size and in terms of the strength of the magnetic field. In particular, a plurality of permanently magnetizable elements may be formed together in a single step, e.g., by molding, on a support structure, such as a lead frame or a printed circuit board (PCB). The permanently magnetizable elements made of a permanently magnetizable material may have any desired shape or form.In particular, the provision of a preform may enable improved shaping of the magnet due to its simplified structure. Detailed description of the characters

[0071] The above and other objects, features and advantages of the present invention will become apparent from the following description and the claims appended hereto, taken in conjunction with the accompanying drawings, in which like parts or elements are designated by like reference numerals.

[0072] The representation in the drawing is schematic and not necessarily to scale.

[0073] Fig. 1 schematically shows a processing method for a set of magnetic semiconductor assemblies 100.

[0074] In particular, Fig. 1A shows a side view of the magnetic semiconductor assemblies 100. The magnetic semiconductor assembly 100 has a carrier structure 101. A plurality of permanently magnetizable elements 102 made of a permanently magnetizable material are formed on the carrier structure 101, e.g., by injection molding, using a moldable or formable, e.g., plastic, material. In particular, each magnetic semiconductor assembly 100 has at least one permanently magnetizable element 102. A portion 103 of the moldable material extends through the carrier substrate 101 and forms a backside taper or undercut portion. The undercut portion or undercut 103 fixes the permanently magnetizable elements 102 to the carrier substrate, so that further adhesive or bonding agent may be omitted.In addition, the widening section or undercut section 103 of the permanently magnetizable element 102 forms a kind of shallow recess 104 in the preform. Fig. 1A. Each of the permanently magnetizable element structures 102 may have a size of, for example, approximately 7 mm x 7 mm x 7 mm, thus forming a relatively large magnetic body or composite that may enable a strong reverse-bias magnetic field with a remanence between 100 mT and 1000 mT after magnetization. The permanently magnetizable element structures 102 may be formed or molded directly on the support structure 101 using metallic permanently magnetizable material and / or non-metallic permanently magnetizable material such as plastic material, e.g., polyphenylene sulfide (PPS) or the like, e.g., by thermoplastic injection molding.

[0075] Fig. 1B shows one of the magnetic semiconductor assemblies 100 of Fig. 1A, in particular a preform or preform structure 111, in plan view. In particular, Fig. 1B shows the support structure 101, which has an insulating beam 112, which enables connecting or fixing several parts of the support structure 101 to each other and may also be used as a stop during the formation or shaping of the permanently magnetizable elements or permanently magnetizable element structures 102. In addition, Fig. 1B shows the undercut section 103, which, viewed from above, is formed substantially around the entire permanently magnetizable element structure. The shape of the permanently magnetizable elements may be substantially a truncated pyramid having a rib formed by the undercut section 103. The undercut sections 103 may thus form the shallow recess 104 with a flat surface or a flat bottom in the center of the permanently magnetizable element structure 102.

[0076] Fig. 1C shows the set of magnetic semiconductor assemblies 100 of Fig. 1A, wherein a semiconductor chip 121, e.g., an integrated circuit (IC) chip or a sensor, is placed on the carrier structure 101 in the shallow recess 104 formed by the permanently magnetizable element, such that the semiconductor chip 121 is surrounded by portions of the permanently magnetizable element 102. The semiconductor 121 is electrically connected, e.g., by wire bonding 122, to contact pads or to the carrier structure 101.

[0077] Fig. 1D shows the same detail as Fig. 1B, but the semiconductor chip 121 in the middle of the preform structure 111 is made of Fig. 1B is placed.

[0078] Fig. 1E shows the set of magnetic semiconductor assemblies 100 of Fig. 1C, wherein the semiconductor chip 121 is encapsulated or molded with a top layer 141, e.g., a passivation layer, forming an overall top surface.

[0079] Fig. 1F shows a single one of the magnetic semiconductor assemblies 100 of Fig. 1E in top view.

[0080] Fig. 1G schematically shows the set of magnetic semiconductor assemblies 100 from Fig. 1E, while electrical testing of the magnetic semiconductor assemblies 100 is performed for the entire set simultaneously, or at least while the magnetic semiconductor assemblies are connected to each other by the carrier structure 101, ie, before singulation. Alternatively, however, the testing may be performed after singulation. The testing is performed by the measuring devices 161 in Fig. 1G is schematically indicated. In addition, the insulation beams 112 are removed and the support structure 101, e.g., the leadframe, is cut through; e.g., a lengthwise conductor cut may be performed.

[0081] Fig. 1H shows a top view of the set of magnetic semiconductor assemblies 100 of Fig. 1G.

[0082] Fig. Figure 1I schematically shows a set of magnetic semiconductor devices 100 after magnetization performed in Fig. 1I is indicated by dashed lines 171, and after singulating the set of magnetic semiconductor assemblies 100.

[0083] Fig. 2 shows schematic views of examples of preform designs according to embodiments.

[0084] Fig. 2A schematically shows a preform 211 that may be used for reverse biasing a Hall sensor. The preform 211 comprises a permanently magnetizable element 202 made of permanently magnetizable material that extends partially through a support structure 201. In particular, the preform 211 has a flat surface 205 that is enclosed or encircled by an undercut 203 of the permanently magnetizable element 202, which extends through the support structure 201. The flat surface 205 may form the bottom of a recess 204 formed by the undercut 203 and enables the placement of a semiconductor, e.g., a sensor, on the flat surface.

[0085] Fig. 2B schematically shows another example of a preform 281. The preform 281 has a permanently magnetizable element 282 made of a permanently magnetizable material, which also extends partially through a support structure 201 and forms an undercut 203 and a boundary of a recess 283. In the example from Fig. 2B, the permanently magnetizable element 202 has a hole 284 extending through the permanently magnetizable element 282, so that a hollow cylinder may be formed. Such a hollow cylinder may be formed using certain adapted thermoplastic molding tools and may be used to manufacture magnetic semiconductor assemblies, e.g., for camshaft sensor applications. In particular, the preform 281 has a flat surface 285 that allows the placement of a semiconductor chip, e.g., a sensor, on the flat surface. Additionally or alternatively, a semiconductor may be placed in the hole 284. A resulting magnetic field may be designed by means of the hole and the shape or form of the hole 284.

[0086] Fig. 2C schematically shows another example of a preform 291. The preform 291 has a permanently magnetizable element 292 made of a permanently magnetizable material, which also extends partially through a support structure 293. In the example of Fig. 2C, the permanently magnetizable element 292 has a recess or notch 294 extending into a flat surface of the permanently magnetizable element 292. The recess 294 may have a roof-like or pyramidal shape, may be formed by a notch in the support structure 293 and, like the hole 284, may be made of Fig. 2B allow modification of the magnetic field generated by the permanently magnetizable element 292.

[0087] Fig. Figure 3 shows schematic views of examples of carrier structures and semiconductors that can be used in a magnetic semiconductor assembly and that, in combination with the Fig. 2 examples of preforms shown can be used.

[0088] In particular, Fig. 3A a preform 311 similar to that in Fig. 2A. The preform 311 comprises a support structure 301 and a permanently magnetizable element 302 comprising a permanently magnetizable material, e.g., a mixture of a base or main compound, e.g., a molding material that may be electrically conductive, and a permanently magnetizable compound such as PPS or a ferromagnetic material. The permanently magnetizable element 302 extends partially through the support structure 301 and forms an undercut 303. In addition, the preform 311 comprises Fig. 3A, an electrical insulation layer 313. The insulation layer 313 is arranged between the permanently magnetizable element 302 and the support structure 301, e.g., a lead frame, and insulates the two parts from each other. For example, the insulation layer 313 may be formed by a protective resin formed in the permanently magnetizable element or the magnetic body 302. The insulation layer may be advantageous if the support structure 301 is just as electrically conductive as the permanently magnetizable element 302.

[0089] In particular, Fig. 3B a preform 321 similar to that in Fig. 2A. The preform 321 comprises a support structure 322 and a permanently magnetizable element 302 comprising a permanently magnetizable material, e.g., a mixture of a base or main compound, e.g., a molding material that may be electrically conductive or insulating, and a permanently magnetizable compound such as PPS or a ferromagnetic material. The permanently magnetizable element 302 extends partially through the support structure 301 and forms an undercut 303. According to the example of Fig. 3B, the support structure 322 is formed by a circuit board, a printed circuit board, or flexible printing materials instead of a lead frame. Fig. 3C and Fig. 3D schematically show two different types of semiconductor chips, IC chips or sensors that can be used in a magnetic semiconductor assembly comprising a permanently magnetizable element 302 and a carrier structure 301. In particular, in Fig. 3C depicts the use of an unpackaged semiconductor chip 331 encapsulated by a passivation layer 332 and bonded to the carrier structure by wire bonding 333. Fig.3D is a schematic illustration of the use of a pre-packaged sensor or sensor module 344 bonded to a support structure 301 by wire bonding 345. It should be noted that the term "comprising" does not exclude other elements or features, and "a" or "an" does not exclude a plurality. Furthermore, elements described in connection with various embodiments may be combined with one another. It should also be noted that reference numerals should not be construed as limiting the scope of the claims.

Claims

[1] A method for producing preforms for magnetic semiconductor assemblies (100), the method comprising: • Forming a plurality of permanently magnetizable elements (102, 202, 282, 292, 302) on a planar carrier structure (101, 201, 293, 301, 322) in a sensor-free region of the carrier structure (101, 201, 293, 301, 322) before a semiconductor chip (121, 331) or sensor is arranged or placed on the carrier structure (101, 201, 293, 301, 322); • wherein the formation is carried out by applying a permanently magnetizable molding material to the carrier structure (101, 201, 293, 301, 322); • wherein a preform (111, 211, 281, 291, 311, 321) has a flat bottom of a recess (104, 204, 283, 294) for placing the semiconductor chip (121, 331) or the sensor; • wherein, in at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302), a portion 103, 203, 303 of the permanently magnetizable molding material extends through the support structure (101, 201, 293, 301, 322) and forms an undercut portion 103, 203, 303 which fixes the permanently magnetizable elements (102, 202, 282, 292, 302) to the support structure (101, 201, 293, 301, 322) and forms a rib which at least partially encloses the flat bottom. [2] The method of claim 1, wherein at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302) is a three-dimensional element, the extent of the element in a first dimension being in the range between 2.5 mm and 25 mm, in a second dimension being in the range between 2.5 mm and 25 mm, and in a third dimension being in the range between 2.5 mm and 25 mm. [3] The method of claim 1 or 2, wherein the permanently magnetizable material comprises electrically conductive material. [4] The method of claim 3, further comprising forming an electrically insulating layer between the support structure and at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302). [5] The method of any one of claims 1 to 4, further comprising singulating the plurality of permanently magnetizable elements (102, 202, 282, 292, 302). [6] The method of any one of claims 1 to 5, further comprising magnetizing at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302). [7] Method according to one of claims 1 to 6, wherein at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302) has a hole. [8] The method of any one of claims 1 to 7, further comprising arranging at least one semiconductor chip (121, 331) on the plurality of permanently magnetizable elements (102, 202, 282, 292, 302). [9] The method of claim 8, further comprising: Encapsulating the at least one semiconductor chip (121, 331) arranged on the plurality of permanently magnetizable elements (102, 202, 282, 292, 302). [10] Preform array for magnetic semiconductor assemblies, the preform array comprising: • a planar support structure and • a plurality of permanently magnetizable elements (102, 202, 282, 292, 302) of a permanently magnetizable material formed on the carrier structure (101, 201, 293, 301, 322) by means of an adhesive-free process, • wherein the plurality of permanently magnetizable elements (102, 202, 282, 292, 302) are formed in a sensor-free region of the carrier structure (101, 201, 293, 301, 322), wherein the sensor-free region of the carrier structure (101, 201, 293, 301, 322) is a region in which no sensors or semiconductor chips (121, 331) are arranged above and below the carrier structure (101, 201, 293, 301, 322), • wherein the area is provided for later arranging a sensor or a semiconductor chip (121, 331) on this area, • wherein a preform (111, 211, 281, 291, 311, 321) has a flat bottom of a recess (104, 204, 283, 294) for placing the semiconductor chip (121, 331) or the sensor; • wherein in at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302) a portion of the permanently magnetizable molding material extends through the support structure (101, 201, 293, 301, 322) and forms an undercut portion 103, 203, 303 which fixes the permanently magnetizable elements (102, 202, 282, 292, 302) to the support structure (101, 201, 293, 301, 322) and forms a rib which at least partially encloses the flat bottom. [11] The preform array of claim 10, wherein each of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302) is a three-dimensional element, the extent of the element (102, 202, 282, 292, 302) in one dimension in the range between 2.5 mm and 25 mm, in a second dimension in the range between 2.5 mm and 25 mm, and in a third dimension in the range between 2.5 mm and 25 mm. [12] Preform array according to claim 10 or 11, wherein the support structure (101, 201, 293, 301, 322) is an electrically conductive support structure. [13] The preform array of claim 12, further comprising an electrically insulating layer between the electrically conductive support structure (101, 201, 293, 301, 322) and each of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302) made of permanently magnetizable material. [14] Preform array according to one of claims 10 to 13, wherein the permanently magnetizable material is electrically insulating. [15] Preform array according to one of claims 10 to 13, wherein the permanently magnetizable material is electrically conductive. [16] A method of manufacturing a magnetic semiconductor assembly (100), the method comprising: Forming a plurality of permanently magnetizable elements (102, 202, 282, 292, 302) made of a permanently magnetizable material on a planar carrier structure (101, 201, 293, 301, 322) before a semiconductor chip (121, 331) or sensor is arranged or placed on the carrier structure (101, 201, 293, 301, 322), wherein a preform (111, 211, 281, 291, 311, 321) has a flat bottom of a recess (104, 204, 283, 294) for placing the semiconductor chip (121, 331) or the sensor, wherein at least one of the plurality of permanently magnetizable elements (102, 202, 282, 292, 302) a section (103) of the permanently magnetizable molding material extends through the support structure (102, 202, 282, 292, 302) and forms an undercut section 103, 203, 303, which fixes the permanently magnetizable elements (102, 202, 282, 292, 302) to the support structure (101, 201, 293, 301, 322) and forms a rib,which at least partially encloses the flat floor;, Placing a semiconductor chip (121, 331) on the flat base.

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