Sensor packaging

Abstract

The present disclosure provides a sensor package. The sensor package may include a substrate including a plurality of layers. The plurality of layers include a first pair of layers and a second pair of layers different from the first pair of layers. The substrate may have a first side and a second side opposite to the first side; the sensor package may include a transducer coupled to the second side of the substrate. The sensor package may include an inductor electrically coupled to the transducer. The inductor may be configured as a single layer trace on an inductor layer within the substrate and disposed between the first pair of layers within the substrate. The first pair of layers may be further away from the second side of the substrate than the second pair of layers.

Description

Technical Field

[0001] The present disclosure relates to a sensor package including a substrate having an inductor layer. Background Art

[0002] Currently, electronic devices such as mobile phones, personal computers, smart speakers, hearing aids, True Wireless Stereo (TWS) headsets, and other host device applications often incorporate one or more small microphones and / or sensors. Advances in micro- and nano-fabrication technology have led to the development of microphones and sensors of increasingly smaller sizes and different form factors. For example, capacitive microelectromechanical systems (MEMS) microphones have replaced the electret microphones that were once primarily used in these and other applications due to their low cost, small size, and high sensitivity. Conducting radio frequency (RF) signals into a MEMS microphone through a pad results in a demodulated signal in the audio band, which is considered noise. Summary of the invention

[0003] One aspect of the present disclosure relates to a sensor package, comprising: a substrate, the substrate comprising a plurality of layers, the plurality of layers comprising a first pair of layers and a second pair of layers different from the first pair of layers, the substrate having a first side and a second side opposite the first side; a transducer, the transducer coupled to the second side of the substrate; and an inductor, the inductor electrically coupled to the transducer, the inductor being configured as a single-layer trace on an inductor layer within the substrate and disposed between the first pair of layers within the substrate, wherein the first pair of layers are further away from the second side of the substrate than the second pair of layers.

[0004] Another aspect of the present disclosure relates to a sensor package, the sensor package comprising: a printed circuit board, the printed circuit board comprising at least four layers, the at least four layers including a bottom layer and a top layer opposite to the bottom layer, the printed circuit board comprising an acoustic port, the acoustic port comprising a hole passing through all the layers of the printed circuit board; a micro-electromechanical system transducer, the micro-electromechanical system transducer mounted on the top layer of the printed circuit board, the micro-electromechanical system transducer comprising a diaphragm and a backplate, the diaphragm being acoustically coupled to the acoustic port; and an inductor, the inductor being connected to the micro-electromechanical system transducer, wherein the inductor is configured as a single-layer trace on an inductor layer within the printed circuit board, the inductor layer being one of the at least four layers, the inductor layer comprising a layer that is closer to the bottom layer of the at least four layers than to the top layer of the at least four layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In order to describe the manner in which the advantages and features of the present disclosure can be obtained, the description of the present disclosure is presented by reference to the specific embodiments of the present disclosure illustrated in the accompanying drawings. These drawings depict only example embodiments of the present disclosure and are therefore not to be considered as limiting the scope thereof. For clarity, the accompanying drawings may have been simplified and are not necessarily drawn to scale.

[0006] Figure 1 is an example illustration of a sensor package with a choked overall ground according to a possible implementation;

[0007] Figure 2 is an example illustration of a sensor package with a choked application specific integrated circuit (ASIC) according to a possible implementation;

[0008] Figure 3 is an example illustration of a sensor package with per-node filters according to a possible implementation;

[0009] Figure 4 is an example circuit diagram with inductors at the input and output according to a possible implementation;

[0010] Figure 5 is an example circuit diagram with an inductor at ground according to a possible implementation;

[0011] Figure 6 is an example circuit diagram with an inductor at ground according to another possible implementation;

[0012] Figure 7 is an example illustration of a sensor package including a cover according to a possible implementation; and

[0013] Figure 8 is an example illustration of an expanded view of a sensor package according to a possible implementation. DETAILED DESCRIPTION

[0014] Embodiments may provide a sensor package including a substrate having an inductor layer. According to possible embodiments, the sensor package may include a substrate including a plurality of layers. The plurality of layers include a first pair of layers and a second pair of layers different from the first pair of layers. The substrate may have a first side and a second side opposite to the first side; the sensor package may include a transducer coupled to the second side of the substrate. The sensor package may include an inductor electrically coupled to the transducer. The inductor may be configured as a single layer trace on an inductor layer within the substrate and disposed between the first pair of layers within the substrate. The first pair of layers may be further away from the second side of the substrate than the second pair of layers.

[0015] Conducting the RF signal into the MEMS microphone through the pads may result in a demodulated signal in the audio band, which may be considered noise. An RF filter may be used on the microphone printed circuit board (PCB), may include capacitors and may include resistors. Capacitor elements may be inexpensive and may therefore be present in minimal quantities. Adding resistors may be expensive and may incur losses including reduced electrostatic discharge robustness and current limiting. Inductors may be used instead of resistors.

[0016] Inductors can be used to increase the electrical impedance of the microphone node at RF frequencies, effectively acting as a filter or mismatch mechanism. The inductor can be created as a single layer trace in a multi-layer PCB, such as a planar coil. One possible implementation may involve a series inductor that may be followed by a shunt capacitor. When high RF currents through the inductor cause heating and associated mechanical distortions (which may appear as sound output), the shunt capacitor can minimize the RF current through the inductor before the series inductor. To this end, according to a possible implementation, the inductor can be on the following layer of the PCB: the layer may be farthest from the top layer where the MEMS microphone or sensor is mounted. For example, the inductor can be placed on the layer directly above the pad, such as in a six-layer PCB structure. When the magnetic attraction or repulsion generated between the inductors causes mechanical excitation of the MEMS microphone or sensor, the planar inductor may not be stacked, such as an inductor on the fifth layer and an inductor on the second layer. It is also possible to use an inductor on a ground return path throughout the sensor package so that all ground currents pass through the inductor, such as when the inductor layer is far enough away from the MEMS, where the inductor can act as a filter for all nodes.

[0017] Figures 1 to 3 , Figure 7 as well as Figure 8 is an exemplary illustration of sensor packages 100, 200, 300, 700, and 800 according to various embodiments. For example, Figure 1 is an example illustration of a sensor package 100 with entire ground choked according to a possible implementation. Figure 2 is an example illustration of a sensor package 200 with a choked ASIC ground according to a possible implementation. Figure 3 is an example illustration of a sensor package 300 with per-node filters according to a possible implementation. Figure 7 is an example illustration of a sensor package 700 including a cover 730 according to a possible implementation. Figure 8is an example illustration of an expanded view of a sensor package 800 according to a possible implementation. According to a possible implementation, the sensor package may be a MEMS sensor package.

[0018] According to various possible embodiments, the sensor package may include a substrate 110 including a plurality of layers including a first pair of layers 112 and a second pair of layers 114 different from the first pair of layers 112. The plurality of layers may include at least three layers. The substrate 110 may have a first side 116 and a second side 118 opposite to the first side 116. The substrate 110 may be a printed circuit board (PCB). For example, the substrate 110 may be a multi-layer PCB. The substrate 110 may also include an acoustic port 170. The sensor package may include a transducer 130 coupled to the second side 118 of the substrate 110.

[0019] The sensor package may include an inductor 120 electrically coupled to a transducer 130. For example, the inductor 120 may be electrically coupled to the transducer 130 via an ASIC 150. The inductor 120 may be configured as a single layer trace on an inductor layer within a substrate 110 and disposed between a first pair of layers 112 within the substrate 110. The inductor 120 may be created as a single layer trace in a multi-layer PCB. The single layer trace may be a planar coil, a meander line, or any other trace occupying a single layer of the substrate 110. In addition to the single layer trace for the inductor 120, other components may also be present on the inductor layer. According to a possible embodiment, the plurality of layers may include at least four layers. The inductor 120 may be an inductor layer of the at least four layers, and the capacitor 140 may be two of the at least four layers.

[0020] The layer may be made of a metal coating. The metal coating may be copper, gold, or any other metal or conductive material that may be etched, grown, or otherwise used as a layer. The metal layer may be a metal plane in the stack of layers of a PCB.

[0021] The first pair of layers 112 can be further away from the second side 118 of the substrate 110 than the second pair of layers 114. The first pair of layers 112 and the second pair of layers 114 can share a common layer or can not share a common layer. For different embodiments, the structure and routing on the layer can be different. For example, different electrical schematics can use different structural layouts.

[0022] The inductor 120 may be on a layer of the substrate 110 that is furthest from the top layer possible, such as the substrate layer having the second side 118, on which the transducer 130 may be mounted. For example, the inductor 120 may be on a layer immediately adjacent to the bottom layer, such as the layer having the substrate first side 116, or may be part of the bottom layer itself.

[0023] Reference Figure 3 , inductor 120 may include multiple inductors on an inductor layer, such as inductors 120 and 122 or more inductors. Capacitor 140 may also include multiple capacitors. For example, one layer may include multiple plates 142 and 144 of different capacitors, while another layer may include one plate 146 common to different capacitors. Multiple capacitors may also be placed on different layers.

[0024] Reference Figures 1 to 3 According to possible embodiments, the sensor package 110 may further include a capacitor 140 electrically coupled to the inductor 120. According to possible embodiments, the capacitor 140 may electrically precede the series inductor 120 in a direction from the microphone pads (such as pads 162 and 164) to the ASIC 150 to minimize the RF current through the inductor 120. According to other possible embodiments, the inductor 120 may electrically precede the capacitor 140.

[0025] The capacitor 140 may be physically placed within the substrate 110. For example, the electrical location may be different from the physical location. To elaborate, a component may be electrically coupled between two components or electrically placed between two components without necessarily being physically placed between the two components.

[0026] According to a possible implementation, the sensor package may include an ASIC 150 coupled to the second side 118 of the substrate 110 . The inductor 120 may be electrically coupled between the ASIC 150 and the capacitor 140 .

[0027] According to a possible implementation, the sensor package may further include a plurality of pads 162, 164, and 166. For example, at least a portion of one of the plurality of layers may include pads placed on a layer including the first side 116 of the substrate 110. The inductor 120 may be placed proximate to the pads, such as pads 162 and 164, between the pads and the second side 118 of the substrate 110. As another example, in a six-layer PCB structure, the inductor may be placed on a layer directly above the pads 162 and 164. Thus, the inductor 120 may be on an available layer farthest from the transducer 130.

[0028] Figures 4 to 6 are example circuit diagrams 400, 500, and 600 of sensor packages according to various embodiments. For example, Figure 4 is an example circuit diagram 400 with inductors on the input and output according to a possible implementation. Figure 5 is an example circuit diagram 500 with an inductor at ground according to a possible implementation. Figure 6 is an example circuit diagram 600 with an inductor at ground according to another possible implementation.

[0029] Circuit diagrams 400, 500, and 600 may include pads 162, 164, and 166. Pad 162 may be a ground pad, pad 164 may be an output pad, and pad 166 may be a voltage source pad. Ground pad 162 may be the actual ground of the sensor package. Microphone pads such as pads 162, 164, and 166 may be a surface mount interface or may be part of a surface mount interface.

[0030] Circuit diagrams 400, 500, and 600 may also include ASICs 152, 154, and 156 corresponding to ASIC 150. ASIC contact 152 may be a ground contact, ASIC contact 154 may be an ASIC output contact, and ASIC contact 156 may be a voltage supply contact. ASIC contacts 152, 154, and 156 may be ASIC bond pads, solder bumps for flip chip applications, or any other contacts.

[0031] The circuit diagrams 400, 500, and 600 may include at least one inductor 420, 520, and 620, such as the inductor 120. The at least one inductor 420, 520, and 620 may include first contacts 422, 522, and 622, respectively, and may include second contacts 424, 524, and 624, respectively.

[0032] Circuit diagrams 400, 500, and 600 may include at least one capacitor 430 and 440, such as capacitor 140. Capacitor 430 may include a first contact 432 and a second contact 434. Capacitor 440 may include a first contact 442 and a second contact 444.

[0033] According to a possible implementation of the circuit diagram 400, the capacitor 430 or 440 may include a first contact 432 or 442 and a second contact 434 or 444. The capacitor second contact 434 or 444 may be electrically coupled to a ground, such as pad ground 162 and / or ASIC ground contact 152. The inductor 420 or 520 may include a first contact 422 or 522 electrically coupled to an ASIC, such as ASIC contact 154 or 156. The inductor 420 or 520 may include a second contact 424 or 524 electrically coupled to the capacitor first contact 442 or 432.

[0034] According to another possible implementation of the circuit diagram 500, the capacitor 430 or 440 may include a first contact 432 or 442 and a second contact 434 or 444. The capacitor second contact 434 or 444 may be electrically connected to ground. The first ASIC contact 154 or 156 may be electrically connected to the capacitor first contact 432 or 442. The inductor first contact 622 may be electrically connected to the ASIC ground contact 152. The inductor second contact 642 may be electrically connected to the capacitor second contact 434 or 444. More contacts (such as more pads) may use more inductors. For example, the sensor package may have more than one output terminal. Therefore, there may be more pads. Many inductors may be used as pad nodes where protection is to be performed.

[0035] According to another possible implementation of the circuit diagram 600, the first capacitor contact 432 or 442 can be electrically coupled to the first pad contact 164 or 166, and the second capacitor contact 434 or 444 can be electrically coupled to ground. The inductor first contact 622 can be electrically coupled to the capacitor second contact 434 or 444, and the inductor second contact 624 can be electrically coupled to the pad ground contact 162.

[0036] Reference Figure 7 and Figure 8 In a possible embodiment, the transducer 130 may include a diaphragm 710 and a back plate 720. The substrate 110 may be a base including an acoustic port 170 that is acoustically coupled to the diaphragm 710. For example, the substrate 110 may be a base of a MEMS sensor package. The acoustic port 170 may be a hole that passes through all layers of the substrate 110.

[0037] According to possible embodiments, the sensor package may include a cover 730 coupled to the substrate 110. The cover 730 may cover the transducer 130. Instead of a substrate having an acoustic port 170, the cover 730 may have an acoustic port 172 that is acoustically coupled to the diaphragm 710. For example, alternatively, or in addition to the acoustic port 170, the acoustic port may be placed anywhere else on the sensor package of any of these embodiments to acoustically couple the diaphragm 710 to an area outside the sensor package.

[0038] Furthermore, the sensor package 700 may include a front cavity volume 742 and a back cavity volume 744, wherein the "front" and "back" labels may be switched if the acoustic port is the acoustic port 172 on the cover 730 instead of the acoustic port 170 on the substrate 110. The sensor package 700 may also include at least one electrical lead 752 from the transducer 130 to the ASIC 150 and at least one electrical lead 754 and / or 756 from the ASIC 150 to the substrate 110. The sensor package 700 may also include a protective coating 760 on the ASIC 150.

[0039] According to possible implementations, there may be no other inductors besides inductor 120 between the layers in a direction perpendicular to the plane of the inductor layers, such as along the z-axis shown relative to sensor package 800. For example, planar inductors may not be stacked, such as having an inductor on one layer and an inductor above or below the inductor on another layer.

[0040] According to a related possible embodiment, the sensor package may include a PCB having at least four layers. The at least four layers may include a bottom layer and a top layer opposite to the bottom layer. The PCB may include an acoustic port, the acoustic port including a hole passing through all layers of the PCB.

[0041] The sensor package may include a MEMS transducer mounted on a top layer of a PCB. The MEMS transducer may include a diaphragm and a backplate. The diaphragm may be acoustically coupled to an acoustic port.

[0042] The sensor package may include an inductor coupled to the MEMS transducer. The inductor may be configured as a single layer trace on an inductor layer within the PCB. The inductor layer may be one of the at least four layers. The inductor layer may be a layer closer to a bottom layer than a top layer of the at least four layers.

[0043] According to a possible implementation, the sensor package may include a capacitor electrically coupled to the inductor. According to a possible implementation, the capacitor may include two layers of the at least four layers.

[0044] According to a possible implementation, the sensor package may include an ASIC coupled to a top layer of the PCB. An inductor may be electrically coupled between the ASIC and the capacitor.

[0045] According to a possible implementation, the capacitor may include a first contact and a second contact. The second contact of the capacitor may be electrically connected to ground. The inductor may include a first contact electrically connected to the ASIC, and may include a second contact electrically connected to the first contact of the capacitor.

[0046] According to a possible implementation, the capacitor may include a first contact and a second contact. The capacitor second contact may be electrically coupled to ground. The ASIC may include a first contact electrically coupled to the capacitor first contact, and may include a ground contact. The inductor may include a first contact electrically coupled to the ASIC ground contact, and may include a second contact electrically coupled to the capacitor second contact.

[0047] According to a possible embodiment, the sensor package may include at least one pad, the at least one pad including a first contact and a second contact. The second contact may be a ground contact. The capacitor may include a first contact electrically coupled to the first contact of the pad, and may include a second contact electrically coupled to the ground. The inductor may include a first contact electrically coupled to the second contact of the capacitor, and may include a second contact electrically coupled to the ground contact of the pad.

[0048] In some implementations, the capacitor may precede the inductor. For example, in some cases, if the inductor precedes the capacitor, there may be high RF currents through the conductor, which may cause thermo-acoustic noise. In some implementations, the inductor may be placed on a layer farther from the MEMS transducer. For example, in some cases, if the inductor is placed on a PCB layer close to the MEMS transducer, then both the position of the inductor relative to the capacitor and the L-type network topology may cause performance degradation due to thermo-acoustic noise. In some implementations, planar inductors may not be stacked. For example, in some cases, the magnetic attraction or repulsion generated between the inductors may cause mechanical excitation of the MEMS.

[0049] Although the present disclosure has been described with respect to its specific embodiments, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, in other embodiments, various components of the embodiments may be interchanged, added, or replaced. Moreover, all elements of the various drawings are not necessary for the operation of the disclosed embodiments. For example, it will enable a person of ordinary skill in the field of the disclosed embodiments to carry out and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure set forth herein are intended to be illustrative rather than limiting. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0050] In this document, relational terms such as "first", "second", etc. can be used alone to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship, or the order between such entities and actions. The phrases "at least one of...", "at least one of the group selected from..." or "at least one of the list selected from..." following a list are defined to refer to one element, some elements, or all but not necessarily all elements in the elements in the list. The term "comprises, comprising, including" or any other variation thereof is intended to cover non-exclusive inclusion, so that the process, method, article, or device including the list of elements does not only include those elements, but may include other elements that are not explicitly listed or inherent to such process, method, article, or device. Elements starting with "a, an", etc. do not exclude the presence of additional identical elements in the process, method, article, or device including the element without more constraints. Moreover, the term "another" is defined as at least the second or more. As used herein, the terms "including", "having" are defined as "comprising". Furthermore, the background section is not admitted to be prior art, but rather is written as the inventor's own understanding of the background of some embodiments at the time of filing, and includes the inventor's own recognition of any problems accompanying the prior art and / or problems experienced in the inventor's own work.

Claims

1. A micro-electromechanical system (MEMS) sensor package, the sensor package comprising: a substrate including a plurality of layers, the plurality of layers including a first pair of layers and a second pair of layers different from the first pair of layers, the substrate having a first side and a second side opposite the first side; a transducer coupled to the second side of the substrate; as well as an inductor electrically coupled to the transducer, the inductor being configured as a single layer trace on an inductor layer within the substrate and disposed between the first pair of layers within the substrate, wherein the first pair of layers is further away from the second side of the substrate than the second pair of layers, Wherein, the transducer comprises a diaphragm and a back plate, wherein the substrate is a base comprising an acoustic port, the acoustic port being acoustically coupled to the diaphragm, wherein the acoustic port comprises a hole passing through all layers of the substrate, wherein there is only one inductor layer among the plurality of layers, and Wherein the acoustic port passes between traces of the inductor. 2 . The MEMS sensor package of claim 1 , further comprising a capacitor electrically coupled to the inductor.

3. The MEMS sensor package according to claim 2, wherein: The capacitor is physically placed within the substrate.

4. The MEMS sensor package of claim 2, further comprising an application specific integrated circuit coupled to the second side of the substrate, in, The inductor is electrically coupled between the ASIC and the capacitor.

5. The MEMS sensor package according to claim 4, in, The capacitor includes a first capacitor contact and a second capacitor contact, the second capacitor contact is electrically coupled to ground, and The inductor includes a first contact electrically coupled to the ASIC and includes a second contact electrically coupled to the first contact of the capacitor.

6. The MEMS sensor package according to claim 4, in, The capacitor comprises a first capacitor contact and a second capacitor contact, the second capacitor contact being electrically coupled to ground, wherein the ASIC includes a first contact electrically coupled to the first contact of the capacitor and includes a ground contact, and The inductor includes a first contact electrically coupled to a ground contact of the ASIC, and includes a second contact electrically coupled to a second contact of the capacitor.

7. The MEMS sensor package according to claim 2, further comprising at least one pad, wherein the at least one pad comprises a first pad contact and a second pad contact, wherein: The second pad contact is a pad ground contact, wherein the capacitor comprises a first capacitor contact electrically coupled to the first pad contact, and comprises a second capacitor contact electrically coupled to ground, and The inductor includes a first contact electrically coupled to the second contact of the capacitor and includes a second contact electrically coupled to the pad ground contact.

8. The MEMS sensor package according to claim 1, in, At least a portion of one of the plurality of layers includes a pad disposed on the first side of the substrate, and The inductor is placed between the pad and the second side of the substrate and adjacent to the pad.

9. The MEMS sensor package according to claim 1, wherein: The plurality of layers includes at least four layers, wherein the inductor includes an inductor layer of the at least four layers, and wherein the MEMS sensor package includes a capacitor including two layers of the at least four layers.

10. A sensor package, comprising: a printed circuit board comprising at least four layers, the at least four layers comprising a bottom layer and a top layer opposite the bottom layer, the printed circuit board comprising an acoustic port, the acoustic port comprising a hole passing through all layers of the printed circuit board; a micro-electromechanical system transducer mounted on the top layer of the printed circuit board, the micro-electromechanical system transducer comprising a diaphragm and a back plate, the diaphragm being acoustically coupled to the acoustic port; as well as an inductor coupled to the micro-electromechanical system transducer, wherein the inductor is configured as a single layer trace on an inductor layer within the printed circuit board, the inductor layer being one of the at least four layers, the inductor layer comprising a layer closer to the bottom layer of the at least four layers than to the top layer of the at least four layers, Wherein, the MEMS transducer comprises a diaphragm and a back plate, wherein the sensor package comprises an acoustic port, the acoustic port being acoustically coupled to the diaphragm, wherein no inductor configured as a single layer trace within the printed circuit board and electrically coupled to the micro-electro-mechanical systems transducer overlaps any other inductor configured as a single layer trace within the printed circuit board and electrically coupled to the micro-electro-mechanical systems transducer in a direction perpendicular to the plane of the inductor layer, and Wherein the acoustic port passes between traces of the inductor. 11 . The sensor package of claim 10 , further comprising a capacitor electrically coupled to the inductor.

12. The sensor package according to claim 11, wherein: The capacitor includes two layers of the at least four layers.

13. The sensor package of claim 11 , further comprising an application specific integrated circuit coupled to the top layer of the printed circuit board, in, The inductor is electrically coupled between the ASIC and the capacitor.

14. The sensor package according to claim 13, wherein: in, The capacitor includes a first capacitor contact and a second capacitor contact, the second capacitor contact is electrically coupled to ground, and The inductor includes a first contact electrically coupled to the ASIC and includes a second contact electrically coupled to the first contact of the capacitor.

15. The sensor package according to claim 13, in, The capacitor comprises a first capacitor contact and a second capacitor contact, the second capacitor contact being electrically coupled to ground, wherein the ASIC includes a first contact electrically coupled to the first contact of the capacitor and includes a ground contact, and The inductor includes a first contact electrically coupled to a ground contact of the ASIC, and includes a second contact electrically coupled to a second contact of the capacitor.

16. The sensor package according to claim 11, further comprising at least one pad, the at least one pad comprising a first pad contact and a second pad contact, wherein: The second pad contact is a pad ground contact, wherein the capacitor comprises a first capacitor contact electrically coupled to the first pad contact, and comprises a second capacitor contact electrically coupled to ground, and The inductor includes a first contact electrically coupled to the second contact of the capacitor and includes a second contact electrically coupled to the pad ground contact.

Images