Optical sensor module

Abstract

Optical Sensor Module This description relates to a substrate assembly (100) for an optical sensor module, the substrate assembly comprising: - a light-emitting device (110) mounted on a first region (101R) of a substrate (101); - a metal shielding assembly comprising a first metal shield (130) assembled to the substrate on the first region; wherein the first metal shield includes a first aperture (131) providing an optical path for the light emitted by the light-emitting device, the first aperture being dimensioned so that said light-emitting device can be inserted through said first aperture into said first metal shield. Figure for the abbreviation: Fig. 1A

Description

Title of the invention: Optical sensor module Technical field

[0001] The present description relates generally to optical sensors, in particular optical sensor modules. Prior art

[0002] Optical sensors, such as proximity sensors, can be used to detect the presence of nearby objects. Optical sensors are able to do this without physically touching the object. Some types of optical sensors, such as those used in optical ranging devices or time-of-flight sensors, can be used to determine the actual distance of these nearby objects. Optical sensors can be used in various electronic devices, such as cameras, phones, including smart phones or smartphones, smart watches or smartwatches, tablets, vehicles, machines and other devices to detect the presence of nearby objects and / or the distance between them.After detecting the presence of a nearby object, the electronic device may be configured to perform a function, such as moving a mechanical element into a safe position, transmitting an alarm signal, coupling or decoupling electrical communication, or any other desired function.

[0003] Optical sensors generally comprise components such as a light-emitting device, a light-receiving sensor, and, in general, a processing device for processing signals received from the light-receiving sensor. The optical sensor components may be formed on a substrate, and a cover may be bonded to the substrate above the components, for example to protect them from damage, thereby forming an optical sensor module, also referred to as an optical sensor housing. The cover is generally formed with a first opening located above the light-emitting device and with a second opening located above the light-receiving sensor.

[0004] Generally, the light emitting device emits a light signal, for example through the first opening of the cover. If an object is outside and sufficiently close to the optical sensor module, the light signal may be reflected by the object towards the light receiving sensor, for example through the second opening of the cover. The light receiving sensor may then generate an electrical signal indicative of the received light signal, which may be transmitted to the processing device for processing said received light signal, for example to determine the presence of the nearby object and / or the distance separating it.

[0005] There is a need to improve optical sensor modules, particularly to address electronic magnetic interference (EMI) issues between an optical sensor module and another electronic device, for example, an electronic device that incorporates the optical sensor module, which may be referred to as a host device, particularly for optical sensors used in consumer electronics. For example, the host device may be a camera, a smartphone, a smartwatch, a tablet, or another device for which it may be useful to detect the presence and / or distance of nearby objects. Summary of the invention

[0006] One embodiment overcomes all or part of the drawbacks of known optical sensor modules.

[0007] One embodiment provides a substrate assembly for an optical sensor module, the substrate assembly comprising: - a light emitting device mounted on a first region of a substrate; - a metal shield assembly comprising a first metal shield assembled to the substrate on the first region; wherein the first metal shield comprises a first opening providing an optical path for light emitted by the light emitting device, the first opening being sized such that said light emitting device can be inserted through said first opening into said first metal shield.

[0008] In one embodiment, the first metal shield is dimensioned to surround and at least partially cover the light emitting device, the first metal shield comprising, for example, a side wall connected to a top wall, the top wall comprising the first opening.

[0009] In one embodiment, the light emitting device comprises: - at least one light source, the first aperture providing an optical path for the light emitted by the at least one light source and being sized such that said at least one light source can be inserted inside said first metal shield and mounted on the substrate through said first aperture; and, optionally, - a photodiode configured to control the light emitting device, the first aperture further providing an optical path for light transmitted to the photodiode, and further being sized such that said photodiode can be inserted within said first metal shield and mounted on the substrate through said first aperture.

[0010] In one embodiment, the substrate assembly further comprises a driver mounted on the first region of the substrate, the driver being configured to control the light emitting device.

[0011] In one embodiment, the first opening extends above the pilot.

[0012] In one embodiment, the first metal shield is electrically coupled strictly to the substrate, for example to a trace of substrate mass.

[0013] In one embodiment, the metal shield assembly further comprises a second metal shield assembled to the first metal shield and at least partially covering the first opening, the second metal shield comprising at least one second opening allowing the passage of light emitted by the, and / or transmitted to the, light emitting device, the second metal shield being for example electrically coupled to, or in contact with, the first metal shield.

[0014] In one embodiment, the second metal shield includes a recessed portion extending into the metal shield assembly.

[0015] In one embodiment, the second metal shield seals the first opening.

[0016] In one embodiment, the second metal shield at least partially closes the first metal shield.

[0017] In one embodiment, the metal shield assembly comprises an absorbing layer positioned on an interior surface of said metal shield assembly that faces the light emitting device, for example on an interior surface of the first metal shield that faces the light emitting device.

[0018] In one embodiment, the substrate assembly further comprises a glass having an electrically conductive trace assembled to the first metal shield above the first opening, the conductive trace being for example electrically coupled to, or in contact with, the first metal shield, for example coupled to a ground trace of the substrate by means of the first metal shield.

[0019] In one embodiment, the metal of the metal shielding assembly is chosen to reflect and / or absorb electromagnetic waves, for example the metal is copper, a copper alloy, stainless steel or any electrically conductive material that also has a relative magnetic permeability greater than 1.

[0020] One embodiment provides an optical sensor module comprising a substrate assembly such as the substrate assemblies described above, and a module cover assembled to the substrate and adapted to at least partially cover the metal shield assembly and components that are mounted on the substrate.

[0021] One embodiment provides a method of manufacturing a substrate assembly for an optical sensor module, the method comprising: - assembling a first metal shield on a substrate above a first region of said substrate, the first metal shield comprising a first aperture providing an optical path for light emitted by a light emitting device to be mounted on the first region; and - mounting the light emitting device on the first region through the first opening.

[0022] In one embodiment, the method further comprises, after the mounting step, assembling a glass comprising an electrically conductive trace to the first metal shield above the first opening, the conductive trace being for example electrically coupled to, or brought into contact with, the first metal shield.

[0023] In one embodiment, the method further comprises, after the mounting step, assembling a second metal shield to the first metal shield in order to at least partially cover the first opening, the second metal shield comprising at least one second opening allowing the passage of light emitted by the, and / or transmitted to the, light emitting device, the second metal shield being for example electrically coupled to, or brought into contact with, the first metal shield. Brief description of the drawings

[0024] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0025] [Fig.1A] is a three-dimensional view of a substrate assembly for an optical sensor module according to one embodiment;

[0026] [Fig.lB] is a sectional view of the substrate assembly of [Fig.lA];

[0027] [Fig.2A], [Fig.2B], [Fig.2C] and [Fig.2D] are top and three-part views dimensions illustrating an exemplary manufacturing process for the substrate assembly of Figures 1A and 1B;

[0028] [Fig.3A] is a three-dimensional view of a substrate assembly for an optical sensor module according to another embodiment;

[0029] [Fig.3B] is a three-dimensional, cross-sectional view showing a detail of the substrate assembly of [Fig.3A];

[0030] [Fig.4] is a three-dimensional view illustrating a variant of the method of Figures 2A to 2D for manufacturing the substrate assembly of Figures 3A and 3B;

[0031] [Fig.5A] is a three-dimensional view of a substrate assembly for a optical sensor module according to another embodiment;

[0032] [Fig.5B] is a three-dimensional, cross-sectional view showing a detail of the substrate assembly of [Fig.5A];

[0033] [Fig.5C] is a three-dimensional view of a variation of the substrate assembly of [Fig.5A];

[0034] [Fig.6A] and [Fig.6B] are top and three-dimensional views illustrating a variation of the method of Figures 2A to 2D for manufacturing the substrate assembly of Figures 5A to 5C;

[0035] [Fig.7] is a three-dimensional view of a substrate assembly for an optical sensor module according to another embodiment; and

[0036] [Fig.8A] and [Fig.8B] are top and three-dimensional views illustrating a variation of the method of Figures 2A to 2D for manufacturing the substrate assembly of [Fig.7]. Description of the embodiments

[0037] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0038] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, not all the components of a substrate assembly have been detailed, the described embodiments being compatible with usual substrate assemblies in optical sensor modules. For example, the light emitting device, the light receiving sensor and other components of an optical sensor, such as a processing device or circuit, have not been detailed. Similarly, not all the components of an optical sensor module have been detailed, the described embodiments being compatible with usual optical sensor modules.

[0039] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0040] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures or to an assembly of substrates or to an optical sensor module as oriented under normal use conditions.

[0041] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0042] In the following description, unless otherwise specified, when reference is made to a glass, it is an element made of a material relatively transparent to light at the wavelengths used, for example having a transmission rate of 90% or more for these wavelengths. This may be, inter alia, a glass or plastic material. The glass may be formed from a single solid material or may be formed by the assembly of several materials, in which case only a portion of the glass may be in a transparent material. The glass may comprise or consist of a lens or a plurality of lenses, and / or an optical filter.

[0043] In the following description, unless otherwise specified, when reference is made to a conductive element, reference is made to an electrically conductive element.

[0044] In the following description, unless otherwise specified, when reference is made to a component, reference is made to an electronic component.

[0045] The term "optical sensor module" includes, but is not limited to, a proximity sensor module, a time-of-flight (ToF) module, an ambient light sensor (ALS) module, a 3D Lidar module, and / or a camera module. The term "optical sensor module" also includes an optical sensor module with combined functions, for example, a combination of at least two of the aforementioned modules, or other functions, for example, a combination of a proximity sensor module with a projector and / or a point projector.

[0046] Embodiments relate to optical sensor modules. An optical sensor generally includes a light-emitting device, for example, including a light-emitting diode (LED) or a laser such as a vertical cavity surface-emitting laser (VCSEL), and a light-receiving sensor, for example, including a photodiode or a plurality of photodiodes. An optical sensor generally also includes a device or circuit for processing signals received from the light-receiving sensor. The light-emitting device and the light-receiving sensor may be formed on a substrate, and a module cover may be assembled on the substrate over the light-emitting device and the light-receiving sensor, thereby forming an optical sensor module, also referred to as an optical sensor package.The light emitting device may comprise a plurality of light sources, for example a plurality of VCSELs.

[0047] The term "substrate assembly" refers to a subassembly of an optical sensor module. The substrate assembly generally includes a substrate and components mounted on the substrate, such as a light-emitting device and a light-receiving sensor. The optical sensor module cover is usually assembled to the substrate on the components mounted on the substrate.

[0048] The optical sensor module may be affected by electromagnetic interference (EMI) with another electronic device.

[0049] For example, when the optical sensor module is included in an electronic device (host device), electromagnetic interference (EMI) may occur between the optical sensor module and the host device. The host device may be a camera, a telephone, for example a smartphone, a smart watch, a tablet, a vehicle, or another device for which it may be useful to detect the presence and / or distance of nearby objects.

[0050] Electromagnetic interference between the optical sensor module and the host device may include: - electromagnetic waves emitted by components of the optical sensor module which may affect components of the host device; and / or - electromagnetic waves emitted by the host device which may affect the performance of the optical sensor module.

[0051] For example, a potential source of electromagnetic waves emitted by the optical sensor module may originate from the light emitting device, for example from a light source of the light emitting device, such as a VCSEL, from a driver such as a laser driver, from inductors or even from conductive wires (wire bonds).

[0052] In addition, environments, such as strong electromagnetic wave environments, e.g., data centers, may also interfere with the components of the optical sensor module and affect its performance.

[0053] In some applications, it is important to control the effect of EMI, for example to protect electronic components and circuits from EMI.

[0054] One solution to overcome electromagnetic interference problems is to add a single metal shield over components sensitive to electromagnetism.

[0055] However, a single metal shield can have a number of disadvantages. A single metal shield may require a large opening for the optical path. Depending on the method used, manufacturing a metal shield may require a large number of steps, for example assembly steps, which incurs high costs and may impair or affect the operation of some components of the optical sensor module. Manufacturing may also introduce slots or gaps in the metal shield, for example for assembly or cleaning of SMT (Surface Mounting Technology) components. surface mount), which can allow electromagnetic waves to pass through, which can be a source of EMI leakage. Optical paths can also be affected by a single metal shield, resulting in an increased or uncontrolled level of external crosstalk within the optical sensor module.

[0056] The inventors propose an optical sensor module making it possible to overcome all or part of the aforementioned drawbacks, in particular to overcome the problems of electromagnetic interference, by using effective and simple protection against EMI, capable of reducing EMI leaks and / or increasing the shielding against EMI, which can avoid altering the operation of certain components of the optical sensor module, and preferably which can avoid increasing the size of the optical sensor module, and complicating the manufacturing process.

[0057] It may also be desirable for the optical sensor module to be able to handle electromagnetic interference through an opening in the EMI shield.

[0058] Embodiments of substrate assemblies for optical sensor modules are described below. These embodiments are not limiting and various variations will become apparent to those skilled in the art from the indications of the present description.

[0059] [Fig.lA] is a three-dimensional view of a substrate assembly 100 for an optical sensor module according to one embodiment. [Fig.lB] is a cross-sectional view of the substrate assembly 100 of [Fig.lA]. The cross-sectional view of [Fig.lB] shows the substrate assembly 100 cut in the direction AA shown in [Fig.lA].

[0060] The substrate assembly 100 comprises a plurality of components mounted on an upper surface 101A of a substrate 101.

[0061] The substrate assembly 100 comprises a light emitting device 110, for example comprising an LED such as an infrared LED, and / or a laser such as a VCSEL or an edge emitting laser (EEL), and a light receiving sensor 120, for example comprising a photodiode or a plurality of photodiodes, such as SPADs, the light emitting device 110 and the light receiving sensor 120 being mounted on the upper surface 101A of a substrate 101. The light emitting device 110 may comprise several light sources.

[0062] The substrate 101 may be a printed circuit board (PCB).

[0063] The light emitting device 110 is configured to emit light signals at a particular frequency or frequency range, and the light receiving sensor 120 is adapted to detect the light signals emitted in return, for example reflected by an object. In one embodiment, the device light emitting sensor 110 is configured to emit infrared (IR) light signals, and light receiving sensor 120 is adapted to detect returning IR light signals, for example reflected by an object.

[0064] For example, the light emitting device 110 may comprise first and second light sources 111, 112, each mounted on the upper surface 101A of the substrate 101, as shown in [Fig. 2D] described below. Only the second light source 112 is shown in Figures 1A and 1B. The first and second light sources 111, 112 are, for example, first and second VCSELs. The light emitting device 110 may also comprise a photodiode 113 mounted on the upper surface 101A of the substrate 101. The photodiode 113 may be dedicated to controlling the light sources.

[0065] In one variant, the light emitting device may comprise a single light source. In another variant, the light emitting device may comprise more than two light sources.

[0066] In one variant, the light emitting device may not include a photodiode and / or include another component for controlling the light source(s). In another variant, the light emitting device may include more than one photodiode.

[0067] The light emitting device 110 may be electrically coupled to the light receiving sensor 120, for example via the substrate 101.

[0068] The substrate assembly 100 may comprise a driver 103, for example a laser driver, configured to control the light emitting device 110, and a processing circuit 104 for processing the light signals emitted by the light emitting device 110 and received by the light receiving sensor 120. The driver 103 and the processing circuit 104 may be mounted on the upper surface 101A of the substrate 101. The driver 103 is for example mounted on the substrate 101 using a ball grid array technique.

[0069] The substrate assembly 100 may include other electrical circuits or components, such as inductors 105 or other surface mount technology (SMT) components 106 that are also mounted on the top surface 101A of the substrate 101. The other SMT components 106 may include resistors. Other SMT components may include capacitors.

[0070] The light emitting device 110, including the light sources 111, 112 and the photodiode 113, the driver 103, the inductors 105 and some of the other SMT components 106 are mounted on a first region 101R of the substrate 101.

[0071] The substrate assembly 100 further comprises a first metal shield 130 mounted on the first region 101R of the substrate 101. The first metal shield 130 is preferably formed and dimensioned to surround and at least partially cover the components, at least the light emitting device 110, the driver 103 and the inductors 105, which are mounted on the first region 10IR. Therefore, the first metal shield 130 advantageously surrounds the potential sources of electromagnetic waves emitted by components of the substrate assembly.

[0072] The first metal shield 130 has side walls 130B connected to a top wall 130A.

[0073] The first metal shield 130 may be referred to as, or included in, a metal shield assembly.

[0074] The first metal shield 130 is electrically coupled to the substrate 101, preferably to a ground trace or ground rail of the substrate 101 to further improve the effectiveness of the EMI shielding, for example to effectively absorb electromagnetic waves.

[0075] The first metal shield 130 comprises a first opening 131 formed in the upper wall 130A, this first opening providing an optical path for the light emitted by the, and possibly transmitted to the, light emitting device 110, that is to say allowing the passage of the light emitted by the, and possibly transmitted to the, light emitting device.

[0076] The first opening 131 is also shaped and sized so that the light emitting device 110, i.e., the light source(s), and optionally the photodiode, can be inserted vertically through this first opening inside the first metal shield 130, in order to be mounted on the substrate 101. The dimensions of the first opening 131 may include sufficient space to mount these components on the substrate 101 through this first opening, depending on the surface mounting method used.

[0077] For example, as illustrated, the surface area of ​​the first opening 131 may be, in a first plane parallel to the plane of the substrate 101, at least equal to the surfaces of the light source(s), and possibly of the photodiode, in the first plane, for example adjusted to the surfaces of the light source(s), and possibly of the photodiode. This makes it possible to limit the surface area of ​​the first opening to the strict minimum for mounting, in order to avoid increasing EMI leaks.

[0078] The surface area of ​​the first opening 131 may be a compromise between EMI shielding and mounting the light source(s), and possibly the photodiode, on the substrate 101 through this first opening.

[0079] The first opening 131 is configured to mount the light source(s), and optionally the photodiode, on the substrate 101, after assembling the first metal shield 130 on the substrate, for example while avoiding affecting or altering the light emitting device 110 during assembly of the first metal shield metal 130 on the substrate 101. This makes it possible, for example, to avoid contaminating the electroluminescent device 110 during an assembly step such as a reflow step.

[0080] In a variant, instead of a single first opening, it may be a plurality of first openings which are not necessarily connected to each other.

[0081] The metal of the first metal shield 130 is preferably chosen to reflect and / or absorb electromagnetic waves generated by the components mounted on the first 10IR region in order to prevent the electromagnetic waves from exiting the substrate assembly 100, as well as the optical sensor module, and for example from affecting a host device. The metal of the first metal shield 130 may also be chosen to reflect and / or absorb electromagnetic waves generated by another electronic device, such as a host device, or electromagnetic waves from the environment, in order to prevent the electromagnetic waves from affecting the performance of the components of the optical sensor module that are mounted on the first region.The metal of the first metal shield is for example copper, or a copper alloy, stainless steel, or any other electrically conductive material which also has a relative magnetic permeability greater than 1.

[0082] The first metal shield 130 further comprises an absorbing layer 132, or EMI absorbing layer, located on the inner surface of the upper wall 130A of this first metal shield. The absorbing layer 132 faces the light emitting device 110. The absorbing layer comprises a material suitable for absorbing electromagnetic waves, for example the EMI absorbing materials marketed by Parker Chomerics under the name CHO-MUTE™, the EMI absorbers marketed by Doosung Corp under the names IDSOB, IDCIM, or the EMI absorbers marketed by Laird. The absorbing layer 132 has an opening that faces the first opening 131 and which preferably has a surface area equal to or greater than the surface area of ​​the first opening.

[0083] Although not shown in Figures 1A and 1B, the optical sensor module generally includes a module cover assembled to the substrate assembly 100 and adapted to at least partially enclose, or cover, the components that are mounted on the substrate, at least the light emitting device and the light receiving sensor. The module cover also covers the metal shield assembly. At least partially means that not all components may be covered. For example, a module cover generally includes a first cover opening located above the emitting device of light and a second cover opening located above the light receiving sensor. The first cover opening preferably faces the first opening of the first metal shield and has a surface area that is preferably equal to or greater than the surface area of ​​this first opening. The module cover may be substantially opaque to light at the wavelengths used. The module cover may be mounted on an opaque adhesive 140, illustrated in [Fig.lA], which is attached to the substrate 101. The module cover may include a partition wall between the light emitting device and the light receiving sensor, to form an optical isolator substantially preventing internal propagation of light beams between the light emitting device and the light receiving sensor.

[0084] Figures 2A, 2B, 2C and 2D are top and three-dimensional views illustrating an exemplary method of manufacturing the substrate assembly 100 of Figures 1A and 1B.

[0085] [Fig.2A] is a top view of a starting structure comprising the substrate 101. The inductors 105 and other SMT components 106 are mounted on the first region 101R of the substrate 101. The driver 103 may also be already mounted on the first region 101R using a surface mount assembly technique, such as a ball grid array technique.

[0086] The first region 101R comprises first conductive pads 102A adapted to receive and connect the light sources 111, 112 and the photodiode 113, and second conductive pads 102B corresponding to, or connected to, the ground trace of the substrate 101.

[0087] [Fig.2B] is a top view of a structure obtained by assembling the first metal shield 130, including the absorbent layer 132, on the substrate 101.

[0088] The assembly of the first metal shield 130 on the substrate 101 may be carried out using a surface mounting technique, for example by forming spots of solder paste on the second conductive pads 102B and bringing the first metal shield 130 into contact with the solder spots, then melting the solder paste to form solder joints 133. Other soldering techniques may be used. The assembly may also be carried out using a conductive adhesive or other means of electrical coupling between the first metal shield and the ground trace of the substrate.

[0089] At the end of this assembly step, the first metal shield 130 is fixed to the substrate 101 and placed in electrical contact with the second conductive pads 102B, and therefore with the ground trace.

[0090] [Fig.2C] is a three-dimensional view of a structure during insertion of the first and second light sources 111, 112 and the photodiode 113 therein. of the first metal shield 130 through the first opening 131.

[0091] The first and second light sources 111, 112 and the photodiode 113 are then mounted on the substrate 101, for example using a chip-attachment method.

[0092] [Fig.2D] is a top view of a structure obtained after electrically connecting each of the first and second light sources 111, 112, and possibly the photodiode 113, to the substrate 101, through the first opening 131, for example using a wire bonding technique. As an example, illustrated in [Fig.2D], conductive wires 114 connect each light source to a third conductive pad 102C of the substrate 101, but other techniques can be used to connect the light sources to the substrate.

[0093] In some embodiments, as illustrated in [Fig.2D], the first conductive pads 102A on which the light source(s), and possibly the photodiode, are to be positioned are entirely visible through the first opening 131 in top view. In other words, an extension of the first opening 131 vertically onto the substrate 101 entirely contains an imprint of the first conductive pads 102A on the substrate 101. This means that, advantageously, the light source(s), and possibly the photodiode, can be lowered directly vertically through the first opening 131 and onto the substrate 101 to their final locations, and can be wired to these first conductive pads.

[0094] The light receiving sensor 120 can then be mounted on the substrate 101, along with other components such as the processing circuit 104.

[0095] Therefore, the components of the substrate assembly 100, such as the light emitting device 110, the driver 103, the inductors 105 or even the conductive wires 114, which may be electromagnetic sources, are surrounded, or contained, at least partially within the first metal shield 130. The first metal shield 130 may be able to absorb and reflect the electromagnetic waves emitted by these components. The first metal shield 130 may also be able to protect these components from electromagnetic waves coming from outside the first metal shield or even from outside the optical sensor module.Furthermore, the absorbing layer 132 of the first metal shield 130 makes it possible to better absorb the electromagnetic waves emitted by the electromagnetic sources, for example emitted by the light emitting device 110, the driver 103, the inductors 105 and / or the conductive wires 114, which reduces the intensity of the EMI power inside this first metal shield, and therefore the EMI leaks. Thus, the first metal shield 130 comprising the absorbing layer 132 makes it possible to reduce the EMI leaks, for example through the first. opening 131, thus providing effective protection against EMI.

[0096] [Fig. 3A] is a three-dimensional view of a substrate assembly 300 for an optical sensor module according to another embodiment. [Fig. 3B] is a three-dimensional and sectional view showing a detail of the substrate assembly 300 of [Fig. 3A]. The three-dimensional and sectional view of [Fig. 3B] shows a detail of the substrate assembly 300 cut to slightly less than half its width in the direction BB shown in [Fig. 3A], and allows a better view of the various components of the substrate assembly located under the first metal shield.

[0097] The substrate assembly 300 of Figures 3A and 3B differs primarily from that of Figures 1A and 1B in that the first opening 131 of the first metal shield 130 is covered by a glass 350 comprising an electrically conductive trace 351. The conductive trace 351 in the glass 350 allows EMI in the first opening 131 to be managed, for example by providing reflection of the EMI in said first opening, thereby limiting EMI leakage and providing effective EMI shielding, even with a large first opening.

[0098] The first metal shield 130 may be referred to as, or included in, a metal shield assembly.

[0099] The conductive material of the trace may be one or more of the following materials: copper (Cu), aluminum (Al), indium tin oxide (ITO), tungsten (W), titanium (Ti), gold (Au).

[0100] The conductive trace 351 shown in FIGS. 3A and 3B forms a mesh or a grid comprising several first linear portions 351A substantially parallel in a first direction of the plane of the glass and second linear portions 351B in a second direction of the plane of the glass. The first and second directions are for example substantially perpendicular to each other. Two adjacent first linear portions are separated by a first distance, or first pitch, in the first direction and two adjacent second linear portions are separated by a second distance, or second pitch, in the second direction. Each of the first and second distances is for example less than or equal to a fraction of the wavelength X, as defined above.

[0101] Each linear portion of the conductive trace 351 may be a thin portion, for example having a thickness of less than 100 nanometers. The first pitch between the first linear portions 351 A, respectively the second pitch between the second linear portions 351 B, may be determined as a function of the frequencies of the EMI to be managed. For example, the higher the frequency, the smaller the pitch may be.

[0102] Each step is for example smaller than the wavelength X of the electromagnetic signal to be attenuated, and is for example a fraction of the wavelength X, where X is equal to:

[0103] ^=7 / where v is the speed of light and f is the electromagnetic background frequency to be attenuated.

[0104] The thickness and pitches of the conductive trace 351 may be a compromise between the EMI shielding function and the optical transmission of the glass 350. For example, the conductive trace may be thicker and / or the pitches smaller when the conductive trace is not likely to affect the desired quality of light transmission, or the conductive trace may be thinner and / or the pitches larger when the conductive trace is likely to affect the desired quality of light transmission.

[0105] Mesh is an example of a pattern that can be used to form the conductive trace, the person skilled in the art can envisage different conductive trace patterns. For example, the conductive trace can include portions that are not perpendicular to each other, for example zigzag patterns, which makes it possible to minimize the distance between the patterns.

[0106] Advantageously, the conductive trace 351 is grounded, in order to provide additional protection against EMI. For example, the conductive trace 351 is electrically coupled, for example in contact with the first metal shield 130, and is coupled to the ground trace of the substrate 101 via the first metal shield 130.

[0107] Examples of conductive trace are described in more detail in French patent application number 2311561, filed on October 25, 2023 in the name of STMICROE-LECTRONICS INTERNATIONAL NV (firm reference B22689), which is incorporated herein by reference to the fullest extent permitted by law.

[0108] Other features of the substrate assembly 300 of Figures 3A and 3B may be similar to those of the substrate assembly 100 of Figures 1A and 1B. The variations described in connection with the substrate assembly 100 of Figures 1A and 1B may also apply to the substrate assembly 300 of Figures 3A and 3B. The optical sensor module of Figures 3A and 3B generally includes a module cover assembled to the substrate assembly 300, similarly to the optical sensor module of Figures 1A and 1B.

[0109] [Fig.3B] shows the EMI absorption layer 132 located on the inner surface of the upper wall 130A of the first metal shield 130. Alternatively, the substrate assembly 300 of FIGS. 3A and 3B may not include an EMI absorption layer.

[0110] The first opening 131 illustrated in Figures 3A and 3B has substantially the same surface area as the first opening of Figures 1A and 1B, but this is not limiting.

[0111] [Fig.4] is a three-dimensional view illustrating a variant of the preceding Figures 2A to 2D for the fabrication of the substrate assembly 300 of Figures 3A and 3B.

[0112] From the structure of [Fig.2D], the glass 350 with the conductive trace 351 is positioned on the upper wall 130A of the first metal shield 130 so as to cover the first opening 131, and so that the conductive trace 351 can come into contact with the first metal shield 130. The conductive trace 351 is then assembled to the upper wall 130A, for example using an electrically conductive glue, such as a conductive epoxy. Preferably, this assembly provides an electrical connection between the conductive trace 351 and the first metal shield 130.

[0113] The light receiving sensor 120 can then be mounted on the substrate 101, along with other components such as the processing circuit 104.

[0114] [Fig. 5A] is a three-dimensional view of a substrate assembly 500 for an optical sensor module according to another embodiment. [Fig. 5B] is a three-dimensional and sectional view showing a detail of the substrate assembly 500 of [Fig. 5A]. [Fig. 5C] is a three-dimensional view of a variation of the substrate assembly of [Fig. 5A]. The three-dimensional and sectional view of [Fig. 5B] shows a detail of the substrate assembly 500 cut to about one-third of its width in the CC direction illustrated in [Fig. 5A], and allows a better view of the various components of the substrate assembly located under the first and second metal shields.

[0115] The substrate assembly 500 of Figures 5A-5C differs primarily from that of Figures 1A and 1B in that the first opening 531 of the first metal shield 530 is not necessarily adapted to the dimensions of the light source(s), and possibly the photodiode, for their mounting on the substrate 101, including the mounting spaces. In other words, a compromise between EMI protection and mounting through the first opening 531 is not necessarily sought, and the first opening 531 may have a large surface area. Furthermore, the substrate assembly 500 includes a second metal shield 534 adapted to be assembled to the first metal shield 530 over the first opening 531 once the light emitting device 110 is mounted and electrically connected to the substrate 101.The shape and dimensions of the second metal shield 534 are preferably adapted to cover the first opening 531. For example, the second metal shield 534 is adapted to seal the first opening 531.

[0116] The first metal shield 530 and the second metal shield 534 form a metal shield assembly.

[0117] The metal of the second metal shield 534 is preferably chosen to reflect and / or absorb: - electromagnetic waves generated by the components mounted on the first region 101R to prevent the electromagnetic waves from exiting the substrate assembly 100, and also the optical sensor module, and for example from affecting a host device; - electromagnetic waves generated by another electronic device, such as a host device, or electromagnetic waves from the environment, to prevent the electromagnetic waves from affecting the performance of the components of the optical sensor module that are mounted on the first region.

[0118] The metal of the second metal shield may be the same as that of the first metal shield.

[0119] The metal shielding assembly advantageously surrounds the potential sources of electromagnetic waves emitted by components of the substrate assembly 500 which are mounted on the first region 101R of the substrate 101, such as the light emitting device 110, the driver 103 (visible in [Fig.6A] described below).

[0120] For example, as shown in [Fig.5B], the second metal shield 534 is larger than the first opening 531 and is positioned to overhang on either side of the first opening, and a solder or conductive adhesive 536 positioned on the top wall 530A of the first metal shield 530 and on the edges of the second metal shield 534 allows the metal shield assembly to be sealed. The use of a solder or conductive adhesive allows the second metal shield to be electrically connected to the first metal shield, for example by coupling the second metal shield to ground via the first metal shield. This assembly technique is a non-limiting example and other assembly techniques may be contemplated by those skilled in the art.For example, the second metal shield may be assembled under the first opening and / or the shape and dimensions of the second metal shield may be adapted to the first opening.

[0121] The first metal shield and the second metal shield may be coupled or connected to each other by welding, for example by laser welding.

[0122] The second metal shield 534 comprises at least one second opening providing an optical path for the light emitted by the, and possibly transmitted to the, light emitting device 110. The second metal shield 534 illustrated in FIGS. 5A to 5C comprises a plurality of second openings: two second openings 535A, 535B providing optical paths 501, 502 for the light emitted respectively by the first light source 111 and the second light source 112, and another second opening 535C allowing the passage of the transmitted light to the photodiode 113. Each second aperture is sized, for example adjusted, for the optical path to be provided.

[0123] As illustrated in [Fig.5B], in some embodiments, the first conductive pads 102A on which the light source(s), and possibly the photodiode, are to be positioned are at least partially hidden by the second metal shield 534 in vertical view through the second openings. In other words, the vertical projection of the second openings on the substrate 101 does not entirely contain the footprint of these first conductive pads on the substrate 101.

[0124] The metal shield assembly of Figures 5A-5C allows for easier mounting and electrical connection of the light emitting device 110, for example the light source(s) and possibly the photodiode, to the substrate 101, before assembling the second metal shield 534 to the first metal shield 530, while limiting the areas of the openings in the metal shield assembly once the second metal shield 534 is assembled, the second openings preferably being primarily dedicated to the optical path(s), thereby limiting EMI leakage and providing effective EMI shielding. In addition, the first opening 531 may be easier to machine than the first opening 131 of Figures 1A and 1B.

[0125] The second metal shield 534 may be substantially flat, as illustrated in [Fig. 5C], or recessed as illustrated in Figures 5A and 5B. The recessed shape of Figures 5A and 5B allows the size of the second openings 535A, 535B, 535C to be restricted, as it allows these second openings to be positioned closer to the light sources 111, 112 and / or the light receiving photodiode 113 of the light emitting device 110, and thus provide better shielding against EMI.

[0126] The first metal shield 530 of FIGS. 5A-5C does not include an EMI absorbing layer. Alternatively, the first metal shield 530 and / or the second metal shield 534 of FIGS. 5A-5C may include an EMI absorbing layer.

[0127] The other elements of the substrate assembly 500 of Figures 5A-5C may be similar to those of the substrate assembly 100 of Figures 1A and 1B. The variations described in relation to the substrate assembly 100 of Figures 1A and 1B may also apply to the substrate assembly 500 of Figures 5A-5C. The optical sensor module of Figures 5A-5C generally includes a module cover assembled to the substrate assembly 500, similarly to the optical sensor module of Figures 1A and 1B.

[0128] The embodiment of Figures 5A to 5C can advantageously be combined with the embodiment of Figures 3A and 3B, that is to say with a glass comprising a conductive trace at least partially covering the second openings of the second metal shield. The conductive trace is preferably electrically coupled to, for example in contact with, the second metal shield, and may be coupled to ground via the second metal shield.

[0129] Figures 6A and 6B are top and three-dimensional views illustrating a variation of the method of Figures 2A to 2D for manufacturing the substrate assembly 500 of Figures 5A to 5C.

[0130] [Fig.6A] is a top view of a starting structure that is similar to the structure of [Fig.2D], except that the first metal shield 530 has a larger first opening 531, and this first opening has a simpler shape. The first and second light sources 111, 112 and the photodiode 113 of the light emitting device 110 have already been mounted and electrically connected to the substrate 101 through this large first opening 531.

[0131] [Fig.6B] is a three-dimensional view of a structure obtained after assembling the second metal shield 534 to the first metal shield 530 to cover the first opening 531, for example using solder or conductive adhesive 536.

[0132] [Fig.7] is a three-dimensional view of the assembly of the substrate 700 for an optical sensor module according to another embodiment.

[0133] The substrate assembly 700 of [Fig. 7] differs primarily from that of Figures 1A and 1B in that the first opening 731 (visible in [Fig. 8A] described below) of the first metal shield 730 is not necessarily adjusted to the dimensions of the light source(s), and possibly the photodiode, for their mounting on the substrate 101, including the mounting spaces, in a manner similar to that of Figures 5A to 5C. In other words, a compromise between EMI protection and the mounting of the first opening is not necessarily sought, and the first opening 731 may have a large surface area. Furthermore, the substrate assembly 700 includes a second metal shield 734 adapted to be assembled to the first metal shield over the first opening 731 once the light emitting device 110 is mounted and electrically connected to the substrate 101.

[0134] The substrate assembly 700 of [Fig. 7] differs primarily from that of Figures 5A-5C in that the second metal shield 734 covers not only the first opening 731, but also the top wall 730A of the first metal shield 730 (the top wall 730A is visible in [Fig. 8A] described below).

[0135] The first metal shield 730 and the second metal shield 734 form a metal shield assembly. For example, the first metal shield 730 forms a metal frame and the second metal shield 734 forms a metal cover.

[0136] The metal shielding assembly advantageously surrounds the potential sources of electromagnetic waves emitted by components of the optical sensor module which are mounted on the first region 101R of the substrate 101, such as the light emitting device 110, the driver 103, the inductors 105 (visible in [Fig.8A] described below).

[0137] In [Fig. 7], the second metal shield 734 is substantially flat. This is not limiting and other shapes may be envisaged by those skilled in the art. For example, in one variation, the second metal shield may be recessed, or may have a recessed portion, for example above the light emitting device, such as the second metal shield 534 of Figures 5A and 5B.

[0138] For example, as shown in [Fig. 7], the second metal shield 734 may be assembled to the side walls 730B of the first metal shield 730. More specifically, the second metal shield 734 has a top wall 734A with edges 734B that are substantially orthogonally curved and extended relative to the top wall. These edges are shaped to surround the upper edges of at least some of the side walls 730B of the first metal shield 730. The second metal shield 734 further includes a fastening tab 736 adapted to cooperate with a slot 733 positioned in the top wall 730A of the first metal shield 730.

[0139] This assembly technique provides an electrical connection between the second metal shield 734 and the first metal shield 730 without using conductive adhesive or solder. Therefore, the second metal shield 734 can be connected to ground by the first metal shield 730. The assembly of the second metal shield 734 of [Fig. 7] may be easier than the assembly of the second metal shield 734 of Figures 5A-5C. This assembly technique is a non-limiting example, and other assembly techniques may be contemplated by those skilled in the art, with or without the use of a conductive adhesive or solder.For example, the second metal shield may have clips adapted to be attached to the side walls of the first metal shield, or may be inserted within and in contact with the side walls of the first metal shield, or the second metal shield may be assembled to the top wall of the first metal shield.

[0140] The upper wall 734A of the second metal shield 734 comprises at least one second opening providing an optical path for light emitted by the, and optionally transmitted to the, light emitting device 110. The second metal shield 734 illustrated in [Fig.7] comprises a plurality of second openings: two second openings 735A, 735B providing optical paths for the light emitted respectively by the first light source 111 and the second light source 112, and another second opening 735C allowing the passage of the light transmitted to the photodiode 113. Each second opening is sized, for example adjusted, for the optical path to be provided.

[0141] The upper wall 734A of the second metal shield 734 may further comprise a third opening 737 adapted to access the fixing tab 736 in order to fix it, and / or to position the second metal shield 734 relative to the first metal shield 730.

[0142] The upper wall 730A of the first metal shield 730 may further comprise fourth openings 732, above the inductors 105, as shown in [Fig.8A] described below, for visual inspection.

[0143] In [Fig. 7], neither the first metal shield 730 nor the second metal shield 734 includes an EMI absorption layer. Alternatively, the first metal shield 730 and / or the second metal shield 734 of [Fig. 7] may include an EMI absorption layer on their inner upper surface.

[0144] The embodiment of [Fig. 7] may be combined with the embodiment of Figures 3A and 3B, i.e. with a glass comprising a conductive trace at least partially covering the second openings and / or the third opening of the second metal shield. The conductive trace is preferably electrically coupled, for example in contact, with the second metal shield, and may be coupled to ground via the second metal shield.

[0145] The other elements of the substrate assembly 700 of [Fig. 7] may be similar to those of the substrate assembly 100 of Figures 1A and 1B. The variations described in relation to the substrate assembly 100 of Figures 1A and 1B may also apply to the substrate assembly 700 of [Fig. 7]. The optical sensor module of [Fig. 7] generally comprises a module cover assembled to the substrate assembly 700, in a manner similar to the optical sensor module of Figures 1A and 1B.

[0146] In some embodiments, the first conductive pads 102A on which the light source(s), and possibly the photodiode, are to be positioned are at least partially hidden by the second metal shield 734 in vertical view through the second openings. In other words, the vertical projection of the second openings on the substrate 101 does not entirely contain the footprint of these first conductive pads on the substrate 101.

[0147] The metal shield assembly of [Fig.7] makes it easier to mount and electrically connect the light emitting device 110, for example the light source(s) and possibly the photodiode, to the substrate 101, as well as to inspect the surface-mounted components before assembling the second metal shield 734 to the first metal shield 730, while limiting the areas of the openings in the metal shield assembly once the second metal shield 734 is assembled, the second openings preferably being primarily dedicated to the optical path(s), thereby limiting EMI leakage and providing effective protection against EMI.

[0148] Figures 8A and 8B are top and three-dimensional views illustrating a variation of the method of Figures 2A to 2D for manufacturing the substrate assembly 700 of [Fig. 7],

[0149] [Fig.8A] is a top view of a starting structure similar to the structure of [Fig.2D], except that the first metal shield 130 is replaced by the first metal shield 730 of [Fig.7]. The first and second light sources 111, 112 and the photodiode 113 of the light emitting device 110 have already been mounted and electrically connected to the substrate 101 through the large first opening 731. The inductors 105, as well as other SMT components 106, are mounted on the substrate 101 and contained within the first metal shield 730.

[0150] [Fig.8A] shows the fourth openings 732 of the first metal shield 730 above the inductors 105, and the slot 733 adapted to cooperate with the fixing tab 736 of the second metal shield 734. As illustrated in [Fig.8A], the first opening 731 may extend above the driver 103, and also above certain other SMT components 106, for example for visual inspection.

[0151] [Fig.8B] is a three-dimensional view of a structure obtained after assembling, for example by fixing with clips, the second metal shield 734 to the first metal shield 730, for example by surrounding the curved edges 734B of the second metal shield around the upper edges of the side walls 730B of the first metal shield, and by inserting the fixing tab 736 into the slot 733.

[0152] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0153] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

Claims

1. A substrate assembly (100; 300; 500; 700) for an optical sensor module, the substrate assembly comprising: - a light emitting device (110) mounted on a first region (101R) of a substrate (101); - a metal shield assembly comprising a first metal shield (130; 530; 730) assembled to the substrate on the first region; wherein the first metal shield comprises a first opening (131; 531; 731) providing an optical path for light emitted by the light emitting device, the first opening being sized such that said light emitting device can be inserted through said first opening into said first metal shield.

2. The substrate assembly (100; 300; 500; 700) of claim 1, wherein the first metal shield (130; 530; 730) is sized to surround and at least partially cover the light emitting device (110), the first metal shield comprising, for example, a side wall (130B; 730B) connected by a top wall (130A; 530A; 730A), the top wall comprising the first opening (131; 531; 731).

3. A substrate assembly (100; 300; 500; 700) according to claim 1 or 2, wherein the light emitting device (110) comprises: - at least one light source (111, 112), the first aperture (131; 531; 731) providing an optical path for light emitted by the at least one light source and being dimensioned such that said at least one light source can be inserted within said first metal shield and mounted on the substrate (101) through said first aperture; and, optionally, - a photodiode (113) configured to control the light emitting device, the first aperture further providing an optical path for light transmitted to the photodiode, and being further dimensioned such that said photodiode can be inserted within said first metal shield and mounted on the substrate through said first aperture.

4. A substrate assembly (100; 300; 500; 700) according to any one of claims 1 to 3, further comprising a driver (103) mounted on the first region (101R) of the substrate (101), the driver being configured to control the light emitting device (110).

5. The substrate assembly (700) of claim 4, wherein the first opening (731) extends above the driver (103).

6. A substrate assembly (100; 300; 500; 700) according to any one of claims 1 to 5, wherein the first metal shield (130) is electrically coupled to the substrate (101), for example to a ground trace of the substrate.

7. The substrate assembly (500; 700) of any one of claims 1 to 6, wherein the metal shield assembly further comprises a second metal shield (534; 734) assembled to the first metal shield (530; 730) and at least partially covering the first opening (531; 731), the second metal shield comprising at least one second opening (535A, 535B, 535C; 735A, 735B, 735C) allowing the passage of light emitted by the, and / or transmitted to the, light emitting device (110), the second metal shield being for example electrically coupled to, or in contact with, the first metal shield.

8. The substrate assembly (500) of claim 7, wherein the second metal shield (534) comprises a recessed portion extending into the metal shield assembly.

9. The substrate assembly (500) of claim 7 or 8, wherein the second metal shield (534) seals the first opening (531).

10. The substrate assembly (700) of any one of claims 7 to 9, wherein the second metal shield (734) at least partially closes the first metal shield (730).

11. A substrate assembly (100; 300) according to any one of claims 1 to 10, wherein the metal shield assembly comprises an absorbing layer (132) positioned on an inner surface of said metal shield assembly that faces the light emitting device (110), for example on an inner surface of the first metal shield (130) that faces the light emitting device.

12. The substrate assembly (300) of any one of claims 1 to 11, further comprising a glass (350) comprising an electrically conductive trace (351) joined to the first metal shield (130) above the first opening (131), the conductive trace being for example electrically coupled to, or in contact with, the first metal shield, for example coupled to a ground trace of the substrate (101) via the first metal shield.

13. The substrate assembly (100; 300; 500; 700) of any one of claims 1 to 12, wherein the metal of the metal shielding assembly is selected to reflect and / or absorb electromagnetic waves, for example the metal is copper, a copper alloy, a stainless steel, or any electrically conductive material that also has a relative magnetic permeability greater than 1.

14. An optical sensor module comprising a substrate assembly according to any one of claims 1 to 13, and a module cover assembled to the substrate and adapted to at least partially cover the metal shield assembly and components that are mounted on the substrate.

15. A method of manufacturing a substrate assembly (100; 300; 500; 700) for an optical sensor module, comprising: - assembling a first metal shield (130; 530; 730) to a substrate (101) on a first region (101R) of said substrate, the first metal shield comprising a first opening (131; 531; 731) providing an optical path for light emitted by a light emitting device (110) to be mounted on the first region; and - mounting the light emitting device (110) on the first region through the first opening.

16. The method of claim 15, further comprising, after the mounting step, assembling a glass (350) comprising an electrically conductive trace (351) to the first metal shield (130) above the first opening (131), the conductive trace being for example electrically coupled to, or brought into contact with, the first metal shield.

17. The method of claim 15 or 16, further comprising, after the mounting step, assembling a second metal shield (534; 734) to the first metal shield (530; 730) to at least partially cover the first opening (531; 731), the second metal shield comprising at least one second opening (535A, 535B, 535C; 735A, 735B, 735C) allowing the passage of light emitted by the, and / or transmitted to the, light emitting device. (110), the second metal shield being for example electrically coupled to, or brought into contact with, the first metal shield.

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