Low frequency shielding solutions with sputtered / sprayed absorbing material and / or absorbing material mixed in the molding compound

Abstract

An electronic device comprising: an electromagnetic interference shield comprising a layer of electrically conductive material covering at least a portion of the electronic device and having a skin depth of less than 2 pm for electromagnetic signals having frequencies in the kilohertz range.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to multi-component microelectronic devices and structures and methods to mitigate electromagnetic crosstalk therein. BACKGROUND

[0002] Modern electronic devices can include modules or packages that house multiple components, such as power amplifiers, low noise amplifiers, voltage controlled oscillators, switches, filters, and other components that operate with alternating current. Market forces continue to demand electronic devices with smaller form factors, lighter and less expensive electronic devices with greater functionality, such as the ability to support multiple frequency bands in electronic communication devices. As a result, circuit density continues to increase in many electronic devices with each new product generation. Electromagnetic interference (EMI) or crosstalk between components in a common electronic device module or between a component in an electronic device module and an external source can degrade overall performance or cause malfunction of the electronic device. SUMMARY

[0003] According to one aspect, an electronic device is provided. The electronic device includes an electromagnetic interference shield comprising a layer of electrically conductive material that covers at least a portion of the electronic device and has a skin depth of less than 2 pm for electromagnetic signals having frequencies in the kilohertz range.

[0004] In some embodiments, the electronic device is covered in a molding material and the electromagnetic interference shield is disposed on the molding material. The molding material can include a filler material that impedes propagation of electromagnetic signals. The filler material can have a skin depth of less than 2 pm for electromagnetic signals having frequencies in the kilohertz range. The filler material can include a magnetic ceramic ferrite. The filler material can include a ferrous alloy. The filler material can be non-conductive. The filler material can include electrically conductive particles surrounded by a non-conductive material.

[0005] In some embodiments, components of the electronic device are configured to emit electromagnetic signals at frequencies in one or more of a hertz range, a kilohertz range, or a megahertz range.

[0006] In some embodiments, the layer of electrically conductive material includes a magnetic ceramic ferrite.

[0007] In some embodiments, the layer of electrically conductive material includes a ferrous alloy.

[0008] In some embodiments, the layer of electrically conductive material has a thickness of less than 30 pm. The layer of electrically conductive material can have a thickness of less than 20 pm.

[0009] In some embodiments, the electronic device further comprises a radio frequency filter. The electronic device can be included in an electronic module.

[0010] According to another aspect, an electronic device is provided. The electronic device comprises: a molding material covering at least a portion of the electronic device and comprising a filler material having a skin depth of less than 2 pm for electromagnetic signals having a frequency in the kilohertz range.

[0011] In some embodiments, the filler material comprises a magnetic ceramic ferrite.

[0012] In some embodiments, the filler material comprises a ferrous alloy.

[0013] In some embodiments, the filler material is non-conductive.

[0014] In some embodiments, the filler material comprises conductive particles covered by a non-conductive material.

[0015] In some embodiments, components of the electronic device are configured to emit electromagnetic signals at frequencies in one or more of the hertz range, the kilohertz range, or the megahertz range.

[0016] In some embodiments, the electronic device further comprises: an electromagnetic interference shield disposed on the molding material, the electromagnetic interference shield comprising a layer of electrically conductive material having a skin depth of less than 2 pm for electromagnetic signals having a frequency in the kilohertz range. The layer of electrically conductive material can comprise a magnetic ceramic ferrite. The layer of electrically conductive material can comprise a ferrous alloy. The layer of electrically conductive material can have a thickness of less than 30 pm. The layer of electrically conductive material can have a thickness of less than 20 pm.

[0017] In some embodiments, the electronic device further comprises a radio frequency filter. The electronic device can be included in an electronic module.

[0018] According to another aspect, a method of forming an electromagnetic interference shield on an electronic device is provided. The method comprises: depositing a molding material on a surface of the electronic device, the molding material comprising a filler material having a skin depth of less than 2 pm for electromagnetic signals having a frequency in the kilohertz range.

[0019] In some embodiments, the method further comprises depositing a layer of electrically conductive material on the molding material, the layer of electrically conductive material having a skin depth of less than 2 pm for electromagnetic signals having a frequency in the kilohertz range.

[0020] According to another aspect, there is provided a method of forming an electromagnetic interference shield on an electronic device. The method comprises: depositing a molding material on a surface of the electronic device; and depositing a layer of electrically conductive material on the molding material, the layer of electrically conductive material having a skin depth of less than 2 pm for electromagnetic signals having a frequency in the kilohertz range. BRIEF DESCRIPTION OF DRAWINGS

[0021] Embodiments of the present application will now be described, by way of non-limiting examples, with reference to the accompanying drawings.

[0022] Figure 1A is an illustration of the use of a first type of shield to suppress electromagnetic interference (EMI) from a power amplifier module;

[0023] Figure 1A is an illustration of the use of a second type of shield to suppress EMI from a power amplifier module;

[0024] Figure 2 shows an electronic device module including a first type of EMI shield;

[0025] Figure 3 shows an electronic device module including a second type of EMI shield;

[0026] Figure 4 shows an electronic device module including a combination of a first type of EMI shield and a second type of EMI shield;

[0027] Figure 5 is a block diagram of one example of a filter module that can include one or more devices according to aspects of the present application;

[0028] Figure 6 is a block diagram of one example of a front-end module that can include one or more devices according to aspects of the present application; and

[0029] Figure 7 is a block diagram of one example of a wireless device including Figure 6 a front-end module. DETAILED DESCRIPTION

[0030] The following description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways. In this specification, reference is made to the drawings where like reference numerals can indicate like or functionally similar elements. Understanding that the elements shown in the drawings can not be to scale, it will be understood that certain embodiments can include more elements than shown in the drawings and / or the subset of elements shown in the drawings. Additionally, some embodiments can incorporate any suitable combination of features from two or more of the drawings.

[0031] Modern electronic devices, for example, communication devices such as cellular phones, can include multiple components that operate at frequencies in the GHz range. For electromagnetic shielding of devices operating at frequencies in the GHz range, a film or layer of conductive material disposed between devices that one wishes to electromagnetically isolate from one another to prevent crosstalk can be used. At such high frequencies, electromagnetic signals do not penetrate deeply into the layer of conductive material, and thus electromagnetic shielding between devices operating at frequencies in the GHz range can be accomplished using a thin film of conductive material (e.g., a metal film having a thickness of 3 pm or less). At lower frequencies, for example, in the MHz, kHz, or Hz range, electromagnetic signals penetrate more deeply into the layer of conductive material than at frequencies in the GHz range. Thus, shielding that can be useful for isolating devices operating in the GHz range can not be sufficient to electromagnetically isolate devices operating at lower frequencies - electromagnetic signals generated by components operating at low frequencies can pass through shielding designed to suppress crosstalk between devices operating at frequencies in the GHz range, and can cause interference or crosstalk between other nearby devices. The extent to which electromagnetic signals penetrate into a conductor can be referred to as the electromagnetic wave skin depth. The skin depth is a measure of the depth in a conductor at which the intensity of electromagnetic radiation falls to l / e of its value near the surface of the conductor, and depends on the frequency of the electromagnetic signal and the material properties of the conductive material. One formula for the skin depth d is:

[0032]

[0033] where p is the resistivity of the conductive material (pΩ-cm), f is the frequency (MHz), and m is the magnetic permeability of the conductive material.

[0034] The skin depths for copper, silver, and nickel at various frequencies are shown in Table 1 below:

[0035] Table 1: Skin depths (pm) for selected materials

[0036] Frequency Copper Silver Nickel 100 kHz 206.2 200.5 17.0 5 MHz 29.1 28.3 2.4 100 MHz 6.52 6.34 0.53 500 MHz 2.93 2.87 0.42 1 GHz 2.07 2.03 0.30 2 GHz 1.46 1.44 0.21 5 GHz 0.93 0.91 0.13 10 GHz 0.65 0.64 0.09 100 GHz 0.21 0.20 0.03

[0037] As can be seen in Table 1 above, a copper film only a few microns thick can be sufficient to shield an electronic component from electromagnetic interference at frequencies in the GHz range, but to shield a component from electromagnetic interference at frequencies in the kHz range, the copper film should be several hundred microns thick. In a typical electronic device manufacturing process, such thick shielding is often impractical or not cost effective.

[0038] One option to provide thin shielding for EMI sensitive devices from electromagnetic interference is to utilize EMI absorbing materials that have higher magnetic permeability and are better electromagnetic energy absorbers than copper, silver or nickel. Such materials can include magnetic ceramic ferrites or ferrous alloys, such as NiFe, CuNiFe / CZT (CZT = Cadmium Zinc Telluride. For high frequency implementations in the GHz range, Cu can make up the majority of the material. For low frequency implementation or implementations in the kHz range, NiFe can make up the majority of the material), or MCF5 magnetic shielding film, which is available from EMR Shielding Solutions and has the chemical formula Co 69 Fe4Mo4NbSi 16 B7. A film of one or more of these materials can be deposited on a packaged device or module, for example, by sputtering, spraying or printing, before or after the packaged device or module is mounted on a carrier (e.g., a printed circuit board). The deposited film thickness can be in a range between about 5 μm and about 30 μm, or in some embodiments, between 0 μm and about 20 μm. The EMI absorbing material can have a skin depth less than one of 3 μm, 2 μm, 1 μm, 0.5 μm or 0.1 μm, or less than the skin depth of copper, silver or nickel at the corresponding frequency shown in Table 1, for electromagnetic signals in the GHz range (1 GHz to 1,000 GHz), the MHz range (1 MHz to 1 GHz), the kHz range (1 kHz to 1 MHz), or the Hz range (1 Hz to 1 kHz).

[0039] Figure 1A and 1B The effectiveness of suppressing EMI from a power amplifier module (Model SKY78140-22 by Skyworks Solutions, Inc.) operating at 127.7 kHz was compared for a device covered with a 3 μm thick conformally deposited copper film with an additional 20 μm thick film of MCF5 placed on the device, and for the same copper film covered device with no additional MCF5 film. The device was placed on a 1.6 mm thick FR4 printed circuit board. Figure 1A and 1B In Table 2, the location of the device under the respective films is indicated by the outline 100. The Cu film suppressed EMI from the device by 63.6 dBm, while the Cu film with the additional MCF5 film suppressed EMI from the device by 90.1 dBm, an improvement of 26.5 dBm.

[0040] Figure 2 An electronic device, e.g., a multi-chip module 200 disposed on a circuit board 205, is shown schematically, covered by a molding material 210, and further covered by a layer of high absorption EMI shielding material 215, e.g., sputtered or sprayed. The molding material 210 can be or can include any typical electronic device molding material, e.g., an epoxy or epoxy-based material.

[0041] One drawback of the EMI shielding approach described above and shown in Figure 2 Another embodiment, which can at least partially address this issue, includes incorporating EMI absorbing material into a molding compound deposited on a device or module. The molding compound can be the same or similar type of molding compound typically used to seal and protect a packaged device or module, e.g., an epoxy or epoxy-based material, but with the addition of EMI absorbing material. Particles or powders of EMI absorbing material, which can be or can include one or more of the magnetic ceramic ferrites or iron-containing alloys described above, can be mixed or blended into the typical packaging module molding material. The particles can have a characteristic size, e.g., a radius, that is at least as large as the skin depth of the material of the particles at the frequency of interest, e.g., at the frequency of electromagnetic interference that the device is expected to generate or that the device can be sensitive to. The particles can have a characteristic size between about 10 μιη and about 100 μιη. The molding material including the EMI absorbing material can then be deposited on the device or module using conventional methods, or directly on the die including the components to be shielded. The EMI absorbing material filler or particles can be non-conductive or conductive with a non-conductive coating to help avoid shorting between exposed leads of the device or module. The molding material including the EMI absorbing material can be deposited to have a thickness typical of molding materials used in the industry, e.g., between 350 μιη and 1000 μιη. The greater thickness of the molding material including the EMI absorbing material can provide greater EMI shielding than a sputtered film of EMI absorbing material (e.g., 3 μιη to 20 μιη thick) compared to. The greater thickness of the molding material compared to a sputtered film can also provide for the use of less absorbing and less expensive EMI absorbing material to achieve equivalent EMI suppression performance as a thinner sputtered or sprayed layer of EMI absorbing material with higher absorption but more expensive. Incorporating the EMI absorbing material into the molding material can also eliminate the need for any special steps to be performed to deposit the EMI absorbing material.

[0042] Figure 3 An electronic device, e.g., a multi-chip module 300 disposed on a circuit board 305, is shown schematically, covered by a molding material 310 including EMI absorbing material.

[0043] It will be appreciated, Figure 2 the embodiments shown in Figure 3 may be combined with the embodiments shown in Figure 2 The molding material 210 of the device of Figure 4 the structure shown in

[0044] The devices described herein can be implemented in various packaging modules. Some example packaging modules in which any suitable principles and advantages of the devices discussed herein can be implemented will now be discussed. Figure 5 、 Figure 6 and Figure 7 are schematic block diagrams of illustrative packaging modules and devices according to certain embodiments.

[0045] Embodiments of the devices disclosed herein can include, for example, filters. In turn, filters using one or more of the devices disclosed herein can be incorporated into and packaged as modules that can ultimately be used in electronic devices such as wireless communication devices. Figure 5 is a block diagram showing one example of a module 400 that includes a filter 410. The filter 410 can be implemented on one or more dies 420 that include one or more connection pads 422. For example, the filter 410 can include a connection pad 422 that corresponds to an input contact of the filter and another connection pad 422 that corresponds to an output contact of the filter. The packaging module 400 includes a packaging substrate 430 configured to house a plurality of components, including the die 420. A plurality of connection pads 432 can be disposed on the packaging substrate 430, and the various connection pads 422 of the filter die 420 can be connected to the connection pads 432 on the packaging substrate 430 via electrical connectors 434, which can be, for example, solder bumps or wire bonds, to allow various signals to be transmitted to and from the filter 410. The module 400 can optionally further include other circuitry dies 440, such as, for example, one or more additional filters, amplifiers, pre-filters, modulators, demodulators, downconverters, etc., as will be known to those skilled in the art of semiconductor fabrication in view of the disclosure herein. In some embodiments, the module 400 can also include one or more packaging structures to, for example, provide protection and facilitate easier handling of the module 400. Such packaging structures can include an overmold formed over the packaging substrate 430 and adapted in size to substantially encase the various circuitry and components thereon. The overmold can include a filter that includes an example of the EMI absorbing material disclosed herein.

[0046] Various examples and embodiments of filter 410 can be used in a wide variety of electronic devices. For example, filter 410 can be used in an antenna duplexer, which itself can be incorporated into various electronic devices such as RF front-end modules and communication devices.

[0047] Referring to Figure 6 , a block diagram of one example of a front-end module 500 is shown, which can be used in an electronic device such as a wireless communication device (e.g., a mobile phone). Front-end module 500 includes an antenna duplexer 510 having a common node 502, an input node 504, and an output node 506. An antenna 610 is connected to common node 502.

[0048] Antenna duplexer 510 can include one or more transmit filters 512 connected between input node 504 and common node 502, and one or more receive filters 514 connected between common node 502 and output node 506. The passband(s) of the transmit filter(s) is different from the passband(s) of the receive filters. Examples of filter 410 can be used to form the transmit filter(s) 512 and / or the receive filter(s) 514. An inductor or other matching component 520 can be connected at common node 502.

[0049] Front-end module 500 further includes a transmitter circuit 532 connected to input node 504 of duplexer 510, and a receiver circuit 534 connected to output node 506 of duplexer 510. Transmitter circuit 532 can generate signals for transmission via antenna 610, and receiver circuit 534 can receive and process signals received via antenna 610. In some embodiments, the receiver and transmitter circuits are implemented as separate components, as shown. However, in other embodiments, these components can be integrated into a common transceiver circuit or module. As will be appreciated by those skilled in the art, front-end module 500 can include other components not shown in Figure 6 , including but not limited to switches, electromagnetic couplers, amplifiers, processors, etc. Figure 6

[0050] Figure 7 is a block diagram of one example of a wireless device 600 that includes antenna duplexer 510 shown in Figure 6 Wireless device 600 can be a cellular telephone, a smart phone, a tablet computer, a modem, a communication network, or any other portable or non-portable device configured for voice or data communication. Wireless device 600 can receive and transmit signals from antenna 610. Wireless device includes a front-end module 500 similar to that described above with reference to Figure 6 Front-end module 500 includes duplexer 510, as described above. In Figure 7 ​In the illustrated example, the front-end module 500 also includes an antenna switch 540, which can be configured to switch between different frequency bands or modes, such as, for example, transmit and receive modes. In Figure 7 In the illustrated example, the antenna switch 540 is located between the duplexer 510 and the antenna 610; however, in other examples, the duplexer 510 can be located between the antenna switch 540 and the antenna 610. In other examples, the antenna switch 540 and the duplexer 510 can be integrated into a single component.

[0051] The front-end module 500 includes a transceiver 530, which is configured to generate signals for transmission or to process received signals. The transceiver 530 can include a transmitter circuit 532 that is connectable to the input node 504 of the duplexer 510, and a receiver circuit 534 that is connectable to the output node 506 of the duplexer 510, as shown in the example of Figure 6

[0052] A power amplifier (PA) module 550 receives the signals generated for transmission by the transmitter circuit 532, and the power amplifier module 550 amplifies the generated signals from the transceiver 530. The power amplifier module 550 can include one or more power amplifiers. The power amplifier module 550 can be used to amplify a variety of RF or other band transmission signals. For example, the power amplifier module 550 can receive an enable signal, which can be used to pulse the output of the power amplifier to assist in transmitting wireless local area network (WLAN) signals or any other suitable pulsed signals. The power amplifier module 550 can be configured to amplify any of a variety of types of signals, including, for example, global system for mobile (GSM) signals, code division multiple access (CDMA) signals, W-CDMA signals, long term evolution (LTE) signals, or EDGE signals. In certain embodiments, the power amplifier module 550 and related components including switches and the like can be fabricated on a gallium arsenide (GaAs) substrate using, for example, high electron mobility transistors (pHEMTs) or insulated gate bipolar transistors (BiFETs), or on a silicon substrate using complementary metal-oxide-semiconductor (CMOS) field effect transistors.

[0053] Still referring to Figure 7 The front-end module 500 can also include a low noise amplifier module 560 that amplifies received signals from the antenna 610 and provides the amplified signals to the receiver circuit 534 of the transceiver 530.

[0054] Figure 7 ​The wireless device 600 also includes a power management subsystem 620 connected to the transceiver 530 and managing power for operation of the wireless device 600. The power management system 620 can also control operation of the baseband subsystem 630 and various other components of the wireless device 600. The power management system 620 can include or be connected to a battery (not shown) that powers the various components of the wireless device 600. The power management system 620 can also include one or more processors or controllers that can control transmission of signals, for example. In one embodiment, the baseband subsystem 630 is connected to a user interface 640 to facilitate various inputs and outputs of voice and / or data provided to and received from a user. The baseband subsystem 630 can also be connected to a memory 650 configured to store data and / or instructions to facilitate operation of the wireless device and / or storage of information for the user. Any of the embodiments described above can be implemented in association with a mobile device such as a cellular handset. The principles and advantages of the embodiments can be applied to any system or device such as any uplink wireless communication device that can benefit from any of the embodiments described herein. The teachings herein are applicable to a variety of systems. Although the present disclosure includes some example embodiments, the teachings described herein can be applied to a variety of structures. Any of the principles and advantages described herein can be implemented in association with RF circuitry configured to process signals in a range from about 30 kHz to 300 GHz, such as in a range from about 450 MHz to 6 GHz.

[0055] Aspects of the application can be implemented in various electronic devices. Examples of electronic devices can include, but are not limited to, consumer electronics, components of consumer electronics such as packaged radio frequency modules, uplink wireless communication apparatuses, wireless communication infrastructure, electronic test equipment, etc. Examples of electronic devices can include, but are not limited to, mobile telephones such as smart phones, wearable computing apparatuses such as smart watches or earphones, telephones, televisions, computer monitors, computers, modems, handheld computers, laptop computers, tablet computers, microwave ovens, refrigerators, in-vehicle electronic systems such as automotive electronic systems, stereo systems, digital music players, radios, cameras such as digital cameras, portable memory chips, washing machines, dryers, washer / dryers, copiers, facsimile machines, scanners, multi-function peripherals, wrist watches, clocks, etc. Furthermore, electronic devices can include unfinished products.

[0056] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," "include," "including," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "coupled" or "coupling" refer to two or more elements that can be either directly connected, or connected with the intervention of one or more intermediate elements. Likewise, as used herein, the term "connected" refers to two or more elements that can be either directly connected, or connected with the intervention of one or more intermediate elements. Also, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above DETAILED DESCRIPTION using the singular or plural number can also include the plural or singular number respectively. The word "or" in reference to a list of two or more items that the word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0057] In addition, conditional language such as, among others, "can," "could," "might," "may," "e.g.," "for example," "e.g.," "for instance," "such as," or the like, unless specifically identified, or otherwise understood from the context, is intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and / or states. Thus, such conditional language is not generally intended to imply that one or more embodiments are required to include a feature, element, and / or state in some way, and, therefore, such conditional language should not be interpreted to restrict a feature, element, and / or state to an embodiment. The

[0058] While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the application. Indeed, the novel methods and systems described herein can be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein can be made without departing from the spirit of the application. For example, while the blocks are presented in a given order, alternative embodiments can perform similar functions by different components and / or circuit topologies, and can perform the blocks in a different order. Each of the blocks can be implemented in a variety of different ways. Any suitable combination of the elements and acts of the various embodiments described above can be combined into other embodiments. The following claims are in no way intended to limit the scope of the application to the particular forms described.

Claims

1. An electronic device, comprising: An electromagnetic interference shielding device includes a conductive material layer covering at least a portion of an electronic device and having a skin depth of less than 2 μm for electromagnetic signals having frequencies in the kilohertz range, the conductive material layer having a thickness of less than 20 μm, the electronic device being encased in a molding material, and the electromagnetic interference shielding device being disposed on the molding material, wherein the molding material includes a filler material that impedes the propagation of electromagnetic signals, the filler material being non-conductive.

2. The electronic device according to claim 1, wherein, The filling material has a skin depth of less than 2 μm for electromagnetic signals with frequencies in the kilohertz range.

3. The electronic device according to claim 1, wherein, The components of the electronic device are configured to emit electromagnetic signals at frequencies within one or more of the Hertz, kilohertz, or megahertz ranges.

4. The electronic device according to claim 1, wherein, The conductive material layer includes magnetic ceramic ferrite.

5. The electronic device according to claim 1, wherein, The conductive material layer includes an iron-containing alloy.

6. The electronic device according to claim 1 further includes a radio frequency filter.

7. An electronic module comprising the electronic device of claim 6.

8. An electronic device, comprising: A molding material and an electromagnetic interference shield disposed on the molding material, the electromagnetic interference shield comprising a conductive material layer having a skin depth of less than 2 μm for electromagnetic signals having frequencies in the kilohertz range, the conductive material layer having a thickness of less than 20 μm, the molding material covering at least a portion of the electronic device and comprising a filler material having a skin depth of less than 2 μm for electromagnetic signals having frequencies in the kilohertz range, wherein the filler material is non-conductive.

9. The electronic device according to claim 8, wherein, The components of the electronic device are configured to emit electromagnetic signals at frequencies within one or more of the Hertz, kilohertz, or megahertz ranges.

10. The electronic device of claim 8, wherein the conductive material layer comprises magnetic ceramic ferrite.

11. The electronic device of claim 8, wherein the conductive material layer comprises an iron-containing alloy.

12. The electronic device according to claim 8, further comprising: Radio frequency filter.

13. An electronic module comprising the electronic device of claim 12.

14. A method for forming an electromagnetic interference shield on an electronic device, the method comprising: A molding material is deposited on the surface of the electronic device, the molding material covering at least a portion of the electronic device and including a filler material having a skin depth of less than 2 μm for electromagnetic signals having frequencies in the kilohertz range, the filler material being non-conductive. as well as A conductive material layer is deposited on the molding material, the conductive material layer having a skin depth of less than 2 μm for electromagnetic signals having frequencies in the kilohertz range, and the conductive material layer having a thickness of less than 20 μm.

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