Electronic LED module and sensor device

Abstract

In various aspects, the present invention provides for an electronic LED module and a sensor device with such an electronic LED module. In illustrative embodiments herein, an electronic LED module (1) comprises a flexible printed circuit board (2) having at least one cavity (4) formed in a surface of the flexible printed circuit board (2) and at least one LED (8) arranged within the at least one cavity (4) of the flexible printed circuit board (2) and attached to the flexible printed circuit board (2). Inner surfaces of the at least one cavity (4) are at least partially covered with a conductive component comprising material (4b) and the at least one LED (8) is encapsulated by a high refractive index material (10).

Description

[0001] Electronic LED Module and Sensor Device

[0002] Field of the Disclosure

[0003] The present invention relates to an electronic LED module for a sensor device and a sensor device with such an electronic LED module.

[0004] Background

[0005] Typically, optical sensors are known as devices that measure the quantity of light rays physically present and turn that information into an electrical signal that can be interpreted by a person or an electronic instrument.

[0006] In important applications, optical sensors are used for monitoring vital signs which may indicate a status of general well-being. For example, optical sensors form the basis for measuring heart rate or the oxygen content in the blood. In particular, such optical sensors may be implemented as special sensors such as accelerometers, heart rate monitors, or on the more advanced side, electrocardiogram (ECG) and blood oxygen saturation (SpO2) monitors.

[0007] Current generation wearables record these values precisely over longer periods of time and show changes, where wearables represent wearable computers or body-borne computers provided as computing devices worn on the body of a user. For example, wearable computers may extend to smartphones or even ordinary wristwatches. A key parameter for general well-being is the so- called heart rate variability (HRV), the HRV showing whether and to what extent a person is under stress or physical strain and how long the recovery phase lasts. As apps and gadgets that record and analyze vital signs require a basis in the form of highly precise measurements, this area of application drives development progress in photodiodes and sensors for precise biomonitoring systems.

[0008] A conventional SpO2 monitoring optical sensor measures the oxygen saturation of the blood, i.e. the proportion of oxygenated hemoglobin in relation to total hemoglobin. This oxygen saturation is measured by sending light of different wavelengths through tissue and analyzing the reflected or transmitted light portions. Such an optical sensor includes an arrangement of light-emitting diodes (LEDs) configured to emit light in a wavelength regions of red light and infrared light as the light in these two wavelength regions allows measuring the quantities of bound (oxygenated) and unbound (non-oxygenated) hemoglobin. From a ratio of these two measured quantities, the percentage of bound hemoglobin is computed. Fig. 1 shows a polar diagram of light intensity of an LED arrangement of a conventional SpO2 sensor. The polar diagram shows measurements of light intensity with the LED arrangement oriented along different directions. A polar region P indicates at different directions lateral losses of radiometric flux and wavelength losses for a conventional optical sensor with this LED arrangement.

[0009] It is an object of the present invention to provide an electronic LED module for a sensor device with such an electronic LED module having an improved uniform radiometric flux output in a desired polar radiation / light emission region.

[0010] Summary of the Disclosure

[0011] The above problems and objects may be at least partially resolved by at least one of an electronic light-emitting diode (LED) module as defined in independent claim 1 and a sensor device as defined in independent claim 17. Advantageous embodiments are defined in dependent claims 2 to 16 and 18.

[0012] In various aspects, the present invention provides for an electronic LED module and a sensor device with such an electronic LED module.

[0013] In a first aspect of the present invention, an electronic LED module for a sensor device is provided. In illustrative embodiments of the first aspect, the electronic LED module comprises a flexible printed circuit board having at least one cavity formed in a surface of the flexible printed circuit board and at least one LED arranged within the at least one cavity of the flexible printed circuit board and attached to the flexible printed circuit board. The cavity may partially expose a conductive material arranged within the flexible printed circuit board. Inner surfaces of the at least one cavity are at least partially covered with a conductive component comprising material. The conductive component comprising material may be a conductive glue (e.g., at least one of silver, nickel, copper and graphite) or a metal (e.g., at least one of silver, nickel, copper, gold etc.) comprising material suitable for plating such that the cavity may be at least partially plated with the metal comprising material. For example, the LED may be mounted within the cavity, e.g. via solder pads within the cavity and contacting plated interior surface regions of the cavity (e.g., a bottom region of the cavity) and / or gluing. A glue may be an electrically non-conductive glue in case of solder attachment, while the glue may be an electrically conductive glue in case of attached to the cavity by electrically conductive die attach via an adhesive layer on a bottom of the cavity. Furthermore, the at least one LED is encapsulated by a high refractive index material. The high refractive index material provides for light being broken to the plumb line at a surface of the high refractive index material facing away from the flexible printed circuit board.

[0014] In accordance with the illustrative embodiments of the first aspect, the at least one cavity allows accommodation of the LED and the high refractive index material so as to configure the electronic LED module for emitting a radiometric flux having improved uniformity.

[0015] In some examples of the illustrative embodiments of the first aspect, manufacturing of the electronic LED module may be improved. For example, the at least one cavity may allow for improved placement and attachment of at least one LED and improved deposition of high refractive index material. An improved positioning of at least one LED and high refractive index material may allow for emission of a radiometric flux having improved uniformity during operation of the electronic LED module.

[0016] In examples herein, the high refractive index material may be understood as representing a material having a refractive index of at least 1 .2 or of at least 1 .3 or of at least 1 .4 or of at least 1 .43 or of at least 1 .45 or of at least 1 .5 such as at least 1 .51 or at least 1 .53. For example, the high refractive index material may be a silicon material having a refractive index in any of the above ranges, preferably a silicon material for use as an encapsulant of LED devices such as a high refractive index silicon with a refractive index of at least 1 .2 or of at least 1 .3 or of at least 1 .4 or of or of at least 1 .43 or of at least 1 .45 or of at least 1 .5 such as at least 1 .51 or at least 1 .53. The silicon material may be a thixotropic silicon material which may be deposited and solidify after deposition without further curing. Alternatively, the silicon material may be a curable silicon material allowing deposition and curing after deposition. In particular examples, the silicon material has a high optical transmission, wherein optical transmission may be understood as a measure of what proportion of light is transmitted through silicon material, having an optical transmission (under this definition) of at least 0.5, preferably of at least 0.6 or 0.7 or 0.8 or 0.9 or 0.95, more preferably of at least 0.96 or 0.97 or 0.98 or 0.99. In some special examples, the silicon material may be a selected as a self-doming material with respect to the surface of the flexible printed circuit board, e.g., a plated surface of the flexible printed circuit board.

[0017] In some illustrative examples of the first aspect, the high refractive index material may be selfdoming material. A self-doming material is a material having mechanical properties such that the material forms a dome shape after deposition on the surface of the flexible printed circuit board. That is, the self-doming material has viscosity and surface tension so as to sit neatly in a dome shape on the surface of the flexible printed circuit board. In accordance with illustrative examples of the first aspect, one cavity may be provided in a surface of the flexible printed circuit board, for example, the cavity may be formed in a main surface of the flexible printed circuit board.

[0018] In first examples herein, one LED may be arranged within the cavity, the LED being configured for emitting light of a first wavelength region. In a special illustrative example herein, the first wavelength region may include wavelengths between 600 and 800 nm. . However, the first wavelength region is not limited to this explicit range and any other appropriate range wavelengths may be used instead.

[0019] In second examples, two LEDs may be arranged within the cavity, one of the LEDs being configured for emitting light of a first wavelength region and the other one of the LEDs being configured for emitting light of a second wavelength region different from the first wavelength region. In a special illustrative example herein, the first wavelength region may include wavelengths between 600 and 700 nm (red light). The second wavelength region may include wavelengths between 700 to 1200 nm (near infrared and infrared light). However, the second wavelength region is not limited to this explicit range and any other appropriate range wavelengths may be used instead.

[0020] In third examples herein, three or more LEDs may be arranged within the cavity, one of the LEDs being configured for emitting light of a first wavelength region, another one of the LEDs being configured for emitting light of a second wavelength region different from the first wavelength region, and still another one of the LEDs being configured for emitting light of a third wavelength region different from the first wavelength region and the second wavelength region etc. At least two of the three or more wavelength regions, may correspond to the first and second wavelength regions as defined in the second examples.

[0021] In accordance with other illustrative examples of the first aspect, two or more cavities may be provided in a surface of the flexible printed circuit board, for example, two or more cavities may be formed in a main surface of the flexible printed circuit board, each cavity accommodating for a dedicated LED of a plurality of LEDs, the LEDs being configured in accordance with LEDs of the third examples.

[0022] In accordance with illustrative examples of the first aspect, the at least one cavity may partially extend into the flexible printed circuit board along a thickness direction such that each of the at least one cavity may have only one opening receiving at least one LED and high refractive index material, the each of the at least one LED being attached to a bottom surface of a respective one from the at least one cavity. The thickness direction is oriented perpendicular to the surface of the flexible printed circuit board.

[0023] In some illustrative embodiments of the first aspect, the at least one cavity may be at least partially plated with a metal material, e.g., at least one of gold, aluminum, copper, silver etc. For example, a bottom of the at least one cavity may be at least partially plated and, optionally, sidewalls of the cavity may be at least partially plated. Accordingly, the plated cavity may allow for LED contacting. In a special illustrative embodiment, the flexible printed circuit board may be a single-sided flexible printed circuit board. In special examples herein and no additional plating may be present inside the at least one cavity of the single sided flexible printed circuit board. Herein, the single sided flexible printed circuit board may comprise a flexible insulating material film, e.g., a polyimide film, laminated to a thin sheet of metal, e.g., copper, forming a metal layer which may be chemically etched to produce a circuit pattern specific to design requirements. A coverlay, e.g., a polyimide coverlay, may be added for insulation and environmental protection of the circuit. Alternatively, the flexible printed circuit board may be a double sided flexible printed circuit board and the at least one cavity may be at least partially plated. Herein, the double sided flex printed circuit board is a flexible printed circuit board having two conductive layers (e.g., copper layers), one on each side of a base layer of insulating material, e.g., polyimide. Trace patterns specific to a user’s needs can be created on both sides of the base layer and can be interconnected where desired via plated holes such that plated holes make electrical connections between the two conductive layers. In some illustrative examples, the holes may be blind holes.

[0024] In embodiments with at least partially plated cavity, plated portions of the at least one cavity may increase light output as a plated surface may act as a reflector. The plated surface may allow the high refractive index material forming a dome when deposited on the plated surface, that is, the high refractive index material may have viscosity and surface tension such that the deposited high refractive index material may form a dome when deposited onto the plated surface.

[0025] In illustrative embodiments of the first aspect, the cavity may be completely formed by a recess in the surface of the flexible printed circuit board.

[0026] In a first illustrative embodiment of the first aspect, the high refractive index material may have a first surface in contact with the flexible printed circuit board and a second surface facing away from the cavity, the second surface being at least partially a curved surface, e.g., a concavely or convexly or generally curved surface. Accordingly, a desired optical effect of the encapsulant provided by the high refractive index material encapsulating for at least one cavity may be adjusted by appropriately designing the second surface as a concavely or convexly or flat or generally curved surface with collimating and / or converging and / or diffusing and / or diffracting effect for implementing an optical element acting as at least one of a lens, a diffusor, and the like. For example, the second surface may be completely curved, such as the second surface being convex or concave or completely curved in a general manner so as to implement a plurality of lenslets (e.g., an array of lenslets or microlenslets etc.), a diffraction grating and the like. In a special illustrative example, the high refractive index material may be dome shaped such that the second surface is purely convex.

[0027] In a first illustrative example of the above first illustrative embodiment, the high refractive index material may completely fill the cavity and the curved surface may be completely outside of the at least one cavity. Accordingly, an advantageous light output may be achieved.

[0028] In a second illustrative example of the first illustrative embodiment above or as a further illustrative example of the first illustrative example above, the second surface of the high refractive index material may be convexly shaped. Accordingly, a collimating or converging effect may be achieved, improving directivity of emitted light.

[0029] In a second illustrative embodiment of the first aspect, the electronic LED module may further comprise a dam structure formed in the surface of the flexible printed circuit board. The dam structure may completely enclose a surface region of the surface and the cavity may be completely formed within the surface region. Accordingly, the dam structure may allow to advantageously delimit the surface region which is to be filled by high refractive index material and avoid lateral loss by the dam structure. The dam structure may be formed by a material with thixotropy allowing to deposit the dam structure while providing a solid dam structure after deposition. In some illustrative examples, the dam structure is not providing a white resin frame.

[0030] In a first illustrative example of the above second illustrative embodiment, the dam structure may define a fill volume bordered by the surface region of the flexible printed circuit board. The fill volume may be at least partially filled by the high refractive index material and / or the fill volume may completely cover the at least one LED. Accordingly, shaping of the high refractive index material may be achieved via the dam structure and / or ensuring complete encapsulation of the at least one LED.

[0031] In a second illustrative example of the second illustrative embodiment above or as a further illustrative example of the first illustrative example above, the dam structure may be formed of a thermoset material comprising a thixotropic nontransparent thermoset material, e.g., a nontransparent thermoplastic, and / or a nontransparent metallic binder component (e.g., a metallic flake as described below in greater detail - the disclosure of which is incorporated by reference) and / or a nontransparent glass binder component (e.g., metal coated or uncoated glass bead(s) such metal coated or uncoated glass microspheres as described below in greater detail - the disclosure of which is incorporated by reference). For example, a non-transparent thermoset material may be a black thermoset material, such as black epoxy material. Accordingly, lateral loss may be further avoided and, possibly, a reflectivity of the dam structure may be adjusted by inclusion of metallic and / or glass components.

[0032] Alternatively, the dam structure may be formed of a thermoset material comprising a thixotropic nontransparent thermoset material, e.g., a nontransparent thermoplastic, and / or a nontransparent metallic component (e.g., a metallic flake as described below in greater detail - the disclosure of which is incorporated by reference) and / or a nontransparent glass component (e.g., metal coated or uncoated glass bead(s) such metal coated or uncoated glass microspheres as described below in greater detail - the disclosure of which is incorporated by reference). For example, a non-transparent thermoset material may be a black thermoset material, such as black epoxy material. Accordingly, lateral loss may be further avoided and, possibly, a reflectivity of the dam structure may be adjusted by inclusion of metallic and / or glass components.

[0033] In any of the second illustrative examples above, the metallic (binder) component(s) may comprise at least one of Al, Ag or Au flakes. For example, such flakes may have a size in a range of about 5 to about 20 pm. In some special illustrative examples herein, flakes may have aspect ratios > 50. Additionally or alternatively, glass (binder) component(s) may comprise silver- or aluminium- plated hollow / solid glass beads or platelets, e.g., having sizes in a range from about 20 to about 70 pm, and / or barium- or titania-rich glass beads or platelets and / or spinel blacks or Zn-doped Ca2MnO4and / or silver-coated and TiO2-primed glass bubbles.

[0034] In a third illustrative example of the second illustrative embodiment above or as a further illustrative example of the first or second illustrative examples above, the dam structure may comprise or be formed by a single layer of dam material or it may comprise or be formed by a stack of at least two layers of dam material (which may represent a dam structure formed of a stacked ring arrangement as opposed to the dam structure formed of a single layer representing a single dam element or simply referred to as a dam). Accordingly, a height of dam structure with respect to a height of the at least one LED may be adjusted to ensure complete encapsulation of the at least one LED. In a third illustrative embodiment of the first aspect, the least one LED may be an LED die and the high refractive index material may be in direct contact with the LED die. Accordingly, light output may be improved.

[0035] In a second aspect of the present invention, a sensor device, such as an optical sensor device, is provided. In illustrative embodiments of the second aspect, the sensor device comprises the electronic LED module of the first aspect, a photodetector, and a casing housing the electronic LED module and the photodetector. The photodetector is arranged and configured for detecting light emitted from the electronic LED module during operation of the sensor device. Accordingly, a sensor device with improved efficiency may be achieved.

[0036] In some illustrative embodiments of the second aspect, the sensor device may be an oximeter sensor device. Accordingly, a very precise oxygen monitoring may be achieved.

[0037] The electronic LED module may be manufactured in a manufacturing process of high-volume production, thereby offering higher productivity and cost effective solution compared to conventional electronic LED modules.

[0038] In the description, the term “glass bead” may generally be understood as sphere, ball, platelet, microsphere, bubble or rod (each of which being one of solid and hollow).

[0039] Brief Description of the Drawings

[0040] Various illustrative embodiments and other advantages of the various aspects of the present disclosure will become apparent from the detailed description of the accompanying Figures as presented below.

[0041] Fig. 1 shows polar diagram of light intensity of an LED arrangement of a conventional SpO2 sensor.

[0042] Fig. 2 schematically shows an electronic LED module in accordance with some illustrative embodiments of the present disclosure.

[0043] Fig. 3 schematically shows an electronic LED module in accordance with some illustrative examples of the illustrative embodiments disclosed with respect to Fig. 2.

[0044] Fig. 4 schematically shows an electronic LED module in accordance with some other illustrative embodiments of the present disclosure. Fig. 5 schematically shows an electronic LED module in accordance with some illustrative examples of the illustrative embodiments disclosed with respect to Fig. 4.

[0045] Fig. 6 schematically shows an electronic LED module in accordance with some other illustrative examples of the illustrative embodiments disclosed with respect to Fig. 4.

[0046] Fig. 7 schematically shows an electronic LED module in accordance with some other illustrative embodiments of the present disclosure.

[0047] Fig. 8 schematically shows a cross-sectional view of a sensor device including an electronic LED module in accordance with illustrative embodiments of the present disclosure.

[0048] Fig. 9 schematically shows a cross-sectional view of a flexible printed circuit board for use in an electronic LED module in accordance with some illustrative embodiments of the present disclosure.

[0049] Fig. 10 schematically shows a cross-sectional view of another flexible printed circuit board for use in an electronic LED module in accordance with some other illustrative embodiments of the present disclosure.

[0050] The Figures accompanying the present disclosure are only provided for schematically showing some concepts and aspects of the present disclosure without showing all possible details of certain embodiments. The illustrations in the Figures are not to scale.

[0051] Detailed Description of Preferred Embodiments

[0052] With regard to Figs. 2 to 10, various illustrative embodiments of an electronic LED module are schematically illustrated and described below in addition to the first aspect described above. The features of various illustrative embodiments of the first aspect as described above may be implemented and combined with the illustrative embodiments as described below.

[0053] Referring to Fig. 9, a flexible printed circuit board FPCB-SS for use in an electronic LED module in accordance with some illustrative embodiments of the present disclosure is illustrated. The flexible printed circuit board FPCB-SS is a single sided flexible printed circuit board. As shown in Fig. 9, the flexible printed circuit board FPCB-SS comprises a metal layer SS-1 , e.g., a thin sheet of metal such as copper, aluminum, etc., laminated to a substrate SS-3, e.g., a polyimide substrate such as a polyimide film, via an adhesive layer SS-2 between the metal layer SS-1 and the substrate SS-3. The metal layer SS-1 may be chemically etched so as to provide a circuit pattern specific to a user’s design requirements in accordance with a patterned metal layer comprising a metal wiring routing. Furthermore, a plating layer SS-4, e.g., a NiAu plating layer, may be deposited on the metal layer SS-1 for protecting the metal layer SS-1 against environmental influences.

[0054] With ongoing reference to Fig. 9, at least one cavity may be formed in the flexible printed circuit board FPCB-SS, e.g., cavity SS-C shown in Fig. 9. The at least one cavity SS-C may extend through the substrate SS-3 so as to partially expose the metal layer SS-1 . The sidewalls of the cavity SS-C expose material of the substrate 3, while a bottom of the cavity SS-C partially exposes the metal layer SS-1 , e.g., tracks of a metal wiring routing of the patterned metal layer. The bottom of the cavity SS-C may be covered with a plating layer SS-5 which may be formed on the exposed metal layer SS-1 in the cavity SS-C when forming the plating layer SS-4 on the metal layer SS-1 as a result of material deposition of the plating layer SS-4 on the metal layer SS-1. In this case, the material of the plating layer SS-4 and the material of the plating layer SS-5 may be identical. However, this does not impose any limitation and the plating layers SS-4 and SS-5 may be deposited or formed in separated process steps and the materials of the plating layers SS-4 and SS- 5 may be different.

[0055] In accordance with some illustrative but non-limiting examples, the plating layer SS-4 and the plating layer SS-5 may be each a bilayer stack formed of a Ni / Au bilayer stack, an Ni sublayer of each bilayer stack being covered by an Au sublayer. However, this does not impose any limitation and only one layer may be formed instead of a bilayer stack or a multilayer stack with more than two sublayers may be formed instead. Additionally or alternatively, different materials from Ni and Au may be used.

[0056] In some illustrative embodiments herein, an LED chip SS-7 is inserted into the cavity SS-C and attached via a conductive glue SS-6, the conductive glue SS-6 partially covering the bottom of the cavity SS-C and being interposed between the LED chip SS-7 and the exposed metal layer SS-1 so as to provide mechanical and electrical connection between the LED chip SS-7 and the metal layer SS-1 . However, this does not impose any limitation and a solder attachment of the LED chip SS-7 to the plating layer SS-5 may be applied instead by using a solder material for attaching the LED chip SS-7 to the plating layer SS-5 or, in some non-illustrated alternative, directly to exposed metal layer SS-1 in the cavity SS-C when omitting the plating layer SS-5 in the cavity SS-C.

[0057] Referring to Fig. 10, a flexible printed circuit board FPCB-DS for use in an electronic LED module in accordance with some other illustrative embodiments of the present disclosure is illustrated. The flexible printed circuit board FPCB-DS is a double sided flexible printed circuit board. As shown in Fig. 10, the flexible printed circuit board FPCB-DS comprises a metal layer DS-1 , e.g., a thin sheet of metal such as copper, aluminum, etc., laminated to a substrate DS-3, e.g., a polyimide substrate such as a polyimide film, via an adhesive layer DS-2 between the metal layer DS- 1 and the substrate DS-3. The metal layer DS-1 may be chemically etched so as to provide a circuit pattern specific to a user’s design requirements in accordance with a patterned metal layer comprising a metal wiring routing. Furthermore, a plating layer DS-4, e.g., a NiAu plating layer, may be deposited on the metal layer DS-1 for protecting the metal layer DS-1 against environmental influences.

[0058] With ongoing reference to Fig. 10, at least one cavity may be formed in the flexible printed circuit board FPCB-DS, e.g., cavity DS-C shown in Fig. 10. The at least one cavity DS-C may extend through the substrate DS-3 so as to partially expose the metal layer DS-1 such that, initially, a bottom of the cavity DS-C may partially exposes the metal layer DS-1 , e.g., tracks of a metal wiring routing of the patterned metal layer, before forming a plating layer DS-8 over the bottom of the cavity DS-C, the plating layer DS-8 being deposited on the bottom of the cavity DS-C via an adhesive layer. Inner sidewalls of the cavity DS-C may be covered by a metal bonding layer DS-7, the metal bonding layer DS-7 in some illustrative examples herein partially covering an exposed surface DS-3S of the substrate DS-3. The metal bonding layer DS-7 may be completely covered by the plating layer DS-8. In some special examples herein, the plating layer DS-8 may comprise NiAu, e.g., a bilayer stack having a Ni sublayer and an Au sublayer, the Ni sublayer being directly deposited on the metal layer DS-1 and the Au sublayer being directly deposited on the Ni sublayer. However, this does not impose any limitation and inner sidewalls of the cavity DS-C may be covered by a single or multilayer (with more than two plating layers) plating layer formed which may be deposited via electroplating or electro-less plating techniques instead.

[0059] An LED chip DS-6 is inserted into the cavity DS-C and attached via a conductive glue DS-5, the conductive glue DS-5 partially covering the bottom of the cavity DS-C and being interposed between the LED chip DS-6 and the plating layer DS-8 so as to provide mechanical and electrical connection between the LED chip DS-6 and the plating layer DS-8. For example, the conductive glue DS-5 and the adhesive layer used for attaching the plating layer DS-8 to the metal layer DS- 1 and possibly the metal bonding layer DS-7 (if present), may be of equal or similar material.

[0060] Still referring to Fig. 10, the flexible printed circuit board FPCB-DS provides for a circuit having two conductive layers via metal layer DS-1 and the metal bonding layer DS-7, each one on each side of the substrate DS-3. Each of the metal layer DS-1 and the metal bonding layer DS-7 may provide fortrace patterns created on both sides of the substrate DS-3 and can be connected where desired with holes via the at least one cavity DS-C having inner sidewalls covered by electrically conductive material, e.g., the metal bonding layer DS-7 and / or the plating layer DS-8.

[0061] Fig. 2 shows, in a schematic cross-sectional view, an electronic LED module 1 comprising a flexible printed circuit board 2 having a cavity 4 formed in a surface 2s of the flexible printed circuit board 2. The flexible printed circuit board 2 may be one of the single sided flexible printed circuit board FPCB-SS as described with respect to Fig. 9 and the double sided flexible printed circuit board FPCB-DS as described with respect to Fig. 10.

[0062] The cavity 4 comprises a material 6 formed at least on a bottom 4b of the cavity 4. As shown in Fig. 2, only the bottom 4b of the cavity 4 may be covered with the material 6. However, this does not impose any limitation and the bottom 4b together with inner sidewalls 4s of the cavity 4 may be covered with the material 6. The material 6 may be a conductive component comprising material.

[0063] In case of the flexible printed circuit board 2 being formed in accordance with the flexible printed circuit board FPCB-SS of Fig. 9, the material 6 corresponds to the conductive glue SS-6 in Fig. 9. Alternatively, the material 6 may be a metal comprising material formed of at least one of gold, silver, copper, and aluminum, or inner sidewalls 4s of the cavity 4 may be at least partially plated with the metal comprising material, in which case the flexible printed circuit board 2 may be formed in accordance with the flexible printed board FPCB-DS of Fig. 10. In some illustrative examples herein, the material 6 may represent the layersDS-5 and DS-8 together with an adhesive layer interposed there between. In some other illustrative examples herein, the cavity 4 may partially expose a conductive track line routed within the flexible printed circuit board 2, this conductive track line representing the metal comprising material. Alternatively, the conductive track line may be plated with the metal comprising material. Thereby, it may be possible to apply an electrical potential to the LED 8.

[0064] The electronic LED module 1 further comprises an LED 8 (e.g., LED chip SS-7 in case of FPCB- SS of Fig. 9 or LED chip DS-6 in case of FPCB-DS of Fig. 10) which is arranged within the cavity 4. Herein, the cavity 4 is completely formed by a recess in the surface 2s of the flexible printed circuit board 2.

[0065] The LED 8 is attached to the flexible printed circuit board 2-by using conductive die-attach glue or by bonding to the material 6 as a metal comprising material in which case the LED 8 may be flipchip bonded to the material 6 as a metal comprising material, where a slot (not illustrated) may be formed in the cavity 4 for separating anode (not illustrated) and cathode (not illustrated) contacts of the LED 8 and to the LED 8.

[0066] With ongoing reference to Fig. 2, the electronic LED module 1 still further comprises a high refractive index material 10, the LED 8 being encapsulated by the high refractive index material 10. The high refractive index material 10 may be formed directly on the LED 8 such that the high refractive index material 10 may be in mechanical contact with an LED die or chip of the LED 8. The high refractive index material 10 completely fills the cavity 4 and completely encapsulates the LED 8. A surface 10s of the high refractive index material 10 facing away from the LED 8 and the flexible printed circuit board 2 is convexly shaped. Fig. 2 schematically shows light rays LR1 indicating light emitted by the LED 8 during operation of the electronic LED module 1. The high refractive index material 10 may implement a collimating optical element resulting from an appropriately shape of the surface 10s of the high refractive index material 10. The high refractive index material 10 may be a self-doming material as described in the context of the first aspect of the disclosure as described above.

[0067] Although Fig. 2 shows the electronic LED module 1 having single LED 8 and single cavity 4, this does not impose any limitation on the present disclosure and the electronic LED module 1 may further comprise one or more additional cavities (not illustrated) formed in the surface 2s of the flexible printed circuit board 2. One or more of additional cavities (not illustrated) may be equipped with at least one additional LED (not illustrated) in a manner similar to cavity 4 being equipped with LED 8.

[0068] With ongoing reference to Fig. 2, the high refractive index material 10 may cover a surface region of the surface 2s of at least the size of the cavity 4. Accordingly, a shaping of the surface 10s of the high refractive index material 10 may be obtained by the high refractive index material 10 having direct mechanical contact with the metal comprising material 6 and / or by directly contacting the surface 2s of the flexible printed circuit board 2.

[0069] Although Fig. 2 shows the surface 10s of the high refractive index material 10 having a convex shape, this does not impose any limitation on the present disclosure and the high refractive index material 10 may have at least one of an at least partially convex and at least partially concave and at least partially planar shaped upper surface facing away from the LED 8. Accordingly, the high refractive index material 10 may be shaped for implementing an optical component with a desired optical effect, e.g., a converging or collimating or dispersing or diffracting effect or a combination thereof. Fig. 3 shows, in a schematic cross-sectional view, an electronic LED module T comprising a flexible printed circuit board 2 having a cavity 4 formed in a surface 2s of the flexible printed circuit board 2. The electronic LED module T may represent illustrative examples of the electronic LED module 1 described above with respect to Fig. 2. Accordingly, similar reference numerals may indicate equal or similar technical features. In particular, the flexible printed circuit board 2’ may be one of the single sided flexible printed circuit board FPCB-SS as described with respect to Fig. 9 and the double sided flexible printed circuit board FPCB-DS as described with respect to Fig. 10, similarly to the description to Fig. 2 in this respect.

[0070] The cavity 4’ is completely formed by a recess in the surface 2s’ of the flexible printed circuit board 2’ and a bottom 4b’ of the cavity 4’ is covered with a material 6’. As shown in Fig. 3, only the bottom 4b’ of the cavity 4’ is covered with the material 6’. However, this does not impose any limitation and the bottom 4b’ together with inner sidewalls 4s’ of the cavity 4’ may be covered with the material 6’. In some special illustrative examples herein, the material 6’ may be an adhesive material such as a conductive glue in accordance with glue SS-6 or it may be a metal comprising material may be formed of at least one of gold, silver, copper, and aluminum. However, this does not impose any limitation and inner sidewalls 4s’ of the cavity 4’ may be also at least partially covered with the material 6’. The material 6’ may be a conductive component comprising material.

[0071] In case of the flexible printed circuit board 2’ being formed in accordance with the flexible printed circuit board FPCB-SS of Fig. 9, the material 6’ corresponds to the conductive glue SS-6 in Fig. 9. Alternatively, the material 6’ is a metal comprising material formed of at least one of gold, silver, copper, and aluminum, or inner sidewalls 4s’ of the cavity 4’ may be at least partially plated with the metal comprising material, in case the flexible printed circuit board 2’ is formed in accordance with the flexible printed board FPCB-DS of Fig. 10. In some illustrative examples herein, the material 6’ may represent the layersDS-5 and DS-8 together with an adhesive layer interposed there between.

[0072] The electronic LED module 1 ’ further comprises an LED 8’ (e.g., LED chip SS-7 in case of FPCB- SS of Fig. 9 or LED chip DS-6 in case of FPCB-DS of Fig. 10) which is arranged within the cavity 4’. The LED 8’ may be attached to the flexible printed circuit board 2’ similar to the LED 8 in the disclosure to Fig. 2 above, the disclosure of which is incorporated by reference in its entirety.

[0073] As shown in Fig. 3, the flexible printed circuit board 2’ further has a cavity 5’ formed in the surface 2s’, the cavity 5’ being formed adjacent to the cavity 4’ separated therefrom by a surface portion 2s1 ’ of the surface 2’. The cavity 5’ may be covered with a material 7’ in analogy to the cavity 4’ having the material 6’ as described above. The LED 8’ has a contact pad C1 formed thereon, the contact pad C1 being connected via a connection line CL with a contact pad C2. In some illustrative examples, the cavity 5’ may partially expose a conductive track line routed within the flexible printed circuit board 2’, the conductive track line possibly representing the material 7’ or possibly being plated with the material 7’ in case of the material 7’ being a metal comprising material or the material 7’ representing a conductive glue in analogy to the material 6’ as described above. Thereby, it is possible to apply an electrical potential to the contact C2. Similarly, the cavity 4’ may partially expose another conductive track line routed within the flexible printed circuit board 2’, this other conductive track line representing the metal comprising material 6’ or being plated with the metal comprising material 6’. Thereby, it is possible to apply an electrical potential to the contact C1 .

[0074] With ongoing reference to Fig. 3, the electronic LED module T still further comprises a high refractive index material 10’, the LED 8’ being encapsulated by the high refractive index material 10’. The high refractive index material 10’ may be formed directly on the LED 8’ such that the high refractive index material 10’ may be in mechanical contact with an LED die or chip of the LED 8’. The high refractive index material 10’ completely fills the cavities 4’ and 5’, the high refractive index material 10’ completely encapsulating the LED 8’, the connection line CL, and the contact C2. A surface 10s’ of the high refractive index material 10’ facing away from the LED 8 and the flexible printed circuit board 2 is convexly shaped. Accordingly, light rays (similar to light rays LR1 shown in Fig. 2 with respect to the electronic LED module 1 ) may be achieved during operation of the electronic LED module T. Accordingly, the high refractive index material 10’ may implement a collimating optical element resulting from an appropriately shape of the surface 10s’ of the high refractive index material 10’. The high refractive index material 10’ may be a self-doming material as described in the context of the first aspect of the disclosure as described above.

[0075] Although Fig. 3 shows the electronic LED module T having single LED 8’, this does not impose any limitation on the present disclosure and the electronic LED module T may further comprise one or more additional LEDs (not illustrated) together with additional cavities (not illustrated) formed in the surface 2s’ of the flexible printed circuit board 2’ similarly to the cavities 4’ and 5’. The one or more of additional cavities (not illustrated) may be equipped with at least one additional LED (not illustrated) in a manner similar to cavity 4’ being equipped with LED 8’ and contacted via an according additional connection line (not illustrated) contacting an additional contact (not illustrated) similar to contact C2.

[0076] With ongoing reference to Fig. 3, the high refractive index material 10’ may cover a surface region of the surface 2s’ of at least a size covering the cavities 4’ and 5’. Accordingly, a shaping of the surface 10s’ of the high refractive index material 10’ may be obtained by the high refractive index material 10’ having direct mechanical contact with the materials 6’, 7’ and / or by directly contacting the surface 2s’ of the flexible printed circuit board 2’. For example, an appropriate dimensioning of the surface portion 2s1 ’ may adjust a shape of the surface 10s’ of the high refractive index material 10’.

[0077] Although Fig. 3 shows the surface 10s’ of the high refractive index material 10’ having a convex shape, this does not impose any limitation on the present disclosure and the high refractive index material 10’ may have at least one of an at least partially convex and at least partially concave and at least partially planar shaped upper surface facing away from the LED 8’. Accordingly, the high refractive index material 10’ may be shaped for implementing an optical component with a desired optical effect, e.g., a converging or collimating or dispersing or diffracting effect or a combination thereof.

[0078] Fig. 4 shows, in a schematic cross-sectional view, an electronic LED module 20. In particular, the flexible printed circuit board 20 may be one of the single sided flexible printed circuit board FPCB- SS as described with respect to Fig. 9 and the double sided flexible printed circuit board FPCB- DS as described with respect to Fig. 10, similarly to the description to Fig. 2 and 3 in this respect. The disclosure above with respect to the single sided flexible printed circuit board FPCB-SS and the double sided flexible printed circuit board FPCB-DS is incorporated at this point in its entirety by reference.

[0079] The electronic LED module 20 comprises a flexible printed circuit board 22 having a cavity 24 (see cavity SS-C or DS-C above in case of the flexible printed circuit board 22 corresponding to one of the flexible printed circuit board FPCB-SS and FPCB-DS) formed in a surface 22s of the flexible printed circuit board 22, the cavity 24 being delimited on the surface 22s of the flexible printed circuit board 22 by a dam structure 25. The dam structure 25 defines a fill volume bordered by a surface region, i.e., the surface region comprising a bottom 24b of the cavity 24, and sidewalls 24s of the cavity 24. The sidewalls 24s of the cavity 24 are formed of inner sidewalls 24s1 of a recess 24r in the flexible printed circuit board 22, and inner sidewalls 24s2 of the dam structure 25. The dam structure 25 completely encloses the surface region of the surface 22s, the cavity 24 being completely formed within the surface region, the dam structure 25 being formed by a single layer of dam material representing a single dam ring completely surrounding the recess 24r.

[0080] The fill volume defined by the cavity 24 may be at least partially filled by the high refractive index material 30. In some illustrative examples herein, the dam structure 25 may be formed of a nontransparent thermoset material, e.g., a nontransparent thermoplastic such as a nontransparent epoxy material comprising a thixotropic nontransparent thermoset material, e.g., a thixotropic nontransparent thermoplastic such as a thixotropic nontransparent epoxy material and / or a thixotropic metallic binder component and / or a thixotropic glass binder component.

[0081] The cavity 24 is may partially covered with a material 26. As shown in Fig. 4, a bottom 24b of the cavity 24 is covered with the material 26. The material 26 may be a conductive component comprising material. For example, the material 26 may be a conductive glue. In some other illustrative examples, the material 26 may comprise at least one of gold, silver, copper, and aluminum plating at least the bottom 24b of the cavity 24 and optionally at least partially sidewalls 24s of the cavity 24. However, this does not impose any limitation and inner sidewalls 24s1 of the recess 24r of the cavity 24 may be at least partially plated with the material 26. Accordingly, light may be reflected by the sidewalls 24s1 of the recess 24r up to a level of plating on the sidewalls 24s1 of the recess 24r.

[0082] In some illustrative examples, the cavity 24, i.e. , the recess 24r in the flexible printed circuit board 22, may partially expose a conductive track line routed within the flexible printed circuit board 22, this conductive track line representing the metal comprising material 26. Alternatively, the conductive track line may be plated with the metal comprising material 26. Thereby, it is possible to apply an electrical potential to the LED 28.

[0083] The electronic LED module 20 further comprises an LED 28 (similarly to the LED chip SS-7 or DS- 6 above in case of the flexible printed circuit board 22 corresponding to one of the flexible printed circuit board FPCB-SS and FPCB-DS) which is arranged within the cavity 24. The fill volume may completely cover the LED 28 (i.e., a height of the dam structure 25 is greater than a height level of the LED 28 or a depth of the cavity 24 is greater than a height of the LED 28).

[0084] As shown in Fig. 4, the cavity 24 is completely filled with the high refractive index material 30. However, this does not impose any limitation and a filling height may only partially fill the fill volume such that the LED 28 is encapsulated, wherein a height of the LED 28 is smaller than a height of the dam structure 25.

[0085] The LED 28 is attached to the flexible printed circuit board 22 by means of a conductive glue as disclosed above or by bonding to the material 26 in case of the material 26 being a metal comprising material. In some examples, the LED 28 may be flip-chip bonded to the material 26 comprising a metal. In case of flip-chip bonding, a slot (not illustrated) may be formed in the cavity 24 for separating anode (not illustrated) and cathode (not illustrated) contacts of the LED 28 and to the LED 28. However, this does not impose any limitation and any other chip attachment or bonding techniques may be employed as described in the context of Fig. 2 and 3 above.

[0086] With ongoing reference to Fig. 4, the electronic LED module 20 still further comprises a high refractive index material 30, the LED 28 being encapsulated by the high refractive index material 30. The high refractive index material 30 may be formed directly on the LED 28 such that the high refractive index material 30 may be in mechanical contact with an LED die or chip of the LED 28.

[0087] As described above, the high refractive index material 30 completely fills the cavity 24 and completely encapsulates the LED 28. Referring to Fig. 4, the high refractive index material 30 completely fills the cavity 24 and a surface 30s of the high refractive index material 30 facing away from the LED 28 and the flexible printed circuit board 22 is convexly shaped. Fig. 4 schematically shows light rays LR2 indicating light emitted by the LED 28 during operation of the electronic LED module 20. The high refractive index material 30 may implement a collimating optical element resulting from an appropriately shape of the surface 30s of the high refractive index material 30. The high refractive index material 30 may be a self-doming material as described in the context of the first aspect of the disclosure as described above.

[0088] Although Fig. 4 shows the electronic LED module 20 having single LED 28 and single cavity 24, this does not impose any limitation on the present disclosure and the electronic LED module 20 may further comprise one or more additional cavities (not illustrated) formed in the surface 22s of the flexible printed circuit board 22. One or more of additional cavities (not illustrated) may be equipped with at least one additional LED (not illustrated) in a manner similar to cavity 24 being equipped with LED 28.

[0089] With ongoing reference to Fig. 4, the high refractive index material 30 may cover a surface region of the surface 22s of at least the size of the cavity 24. Accordingly, a shaping of the surface 30s of the high refractive index material 30 may be obtained by the high refractive index material 30 having direct mechanical contact with the metal comprising material 26 and / or by directly contacting the surface 22s of the flexible printed circuit board 22.

[0090] Although Fig. 4 shows the surface 30s of the high refractive index material 30 having a convex shape, this does not impose any limitation on the present disclosure and the high refractive index material 30 may have at least one of an at least partially convex and at least partially concave and at least partially planar shaped upper surface facing away from the LED 28. Accordingly, the high refractive index material 30 may be shaped for implementing an optical component with a desired optical effect, e.g., a converging or collimating or dispersing or diffracting effect or a combination thereof.

[0091] Fig. 5 shows, in a schematic cross-sectional view, an electronic LED module 20’. The electronic LED module 20’ may represent illustrative examples of the electronic LED module 20 described above with respect to Fig. 4. Accordingly, similar reference numerals may indicate equal or similar technical features. In particular, the flexible printed circuit board 20’ may be one of the single sided flexible printed circuit board FPCB-SS as described with respect to Fig. 9 and the double sided flexible printed circuit board FPCB-DS as described with respect to Fig. 10, similarly to the description to Fig. 2 to 4 in this respect. The disclosure above with respect to the single sided flexible printed circuit board FPCB-SS and the double sided flexible printed circuit board FPCB-DS is incorporated at this point in its entirety by reference.

[0092] The electronic LED module 20’ comprises a flexible printed circuit board 22’ having a cavity 24’ formed in a surface 22s’ of the flexible printed circuit board 22’, and an LED 28’ which is arranged within the cavity 24’. The cavity 24’ is delimited on the surface 22s’ of the flexible printed circuit board 22’ by a dam structure 25’. The dam structure 25’ defines a fill volume bordered by a surface region of the flexible printed circuit board 22’. The fill volume may completely cover the LED 28’ (i.e. , a height of the dam structure 25’ is greater than a height level of the LED 28’ or a depth of the cavity 24’ is greater than a height of the LED 28’). Sidewalls 24s’ of the cavity 24’ are formed of inner sidewalls 24s1 ’ of a recess 24r1 ’ in the flexible printed circuit board 22’, inner sidewalls 24s3’ of a recess 24r2’ in the flexible printed circuit board 22’, and inner sidewalls 24s2’ of the dam structure 25’. The surface region comprises a bottom 24b’ of the recess 24r1 ’ and a bottom 25’ of the recess 24r2’.That is, the dam structure 25’ completely encloses the surface region of the surface 22s’, the recesses 24r1 ’ and 24r2’ being completely formed within the surface region. The dam structure 25’ is formed by a single layer of dam material representing a single dam ring completely surrounding the recesses 24r1 ’ and 24r2’. The recesses 24r1 ’ and 24r2’ are formed adjacent to the cavity recess 24r1 ’ separated therefrom by a surface portion 22s1 ’ of the surface 22’.

[0093] The recess 24r1 ’ may be at least partially covered with material 26’ and the recess 24r2’ may be at least partially covered with material 27’ (which may be equal to the material 26’ or both materials may be different materials). For example, only the bottom 25b’ of the recess 24r2’ may be covered with the material 27’. The material 27’ may be a conductive component comprising material. In some examples herein, the material 27’ may be formed of conductive glue or of at least one of gold, silver, copper, and aluminum. However, this does not impose any limitation and inner sidewalls 25s’ of the recess 24r2’ may be at least partially covered with the material 27’. The LED 28’ has a contact pad C3 formed thereon, the contact pad C3 being connected via a connection line CLa with a contact pad C4.

[0094] The recess 24r1 ’ is partially covered with material 26’. The material 26’ may be a conductive component comprising material. The material 26’ may be formed of conductive glue or of at least one of gold, silver, copper, and aluminum. However, this does not impose any limitation and inner sidewalls 24s1 ’ of the recess 24r1 ’ of the cavity 24’ may be at least partially covered with the material 26’. In case of the material 26’ comprising a metal, light may be reflected by the sidewalls 24s1 ’ of the recess 24r1 ’ up to a level of plating on the sidewalls 24s1 ’ of the recess 24r1 ’.

[0095] In some illustrative examples, the recess 24r1 ’ in the flexible printed circuit board 22’ may partially expose a conductive track line routed within the flexible printed circuit board 22’, this conductive track line representing the material 26’ comprising metal. Alternatively, the conductive track line may be plated with the material 26’ comprising metal or covered with a conductive glue. Thereby, it is possible to apply an electrical potential to the LED 28’.

[0096] In some illustrative examples, the recess 24r2’ may partially expose a conductive track line routed within the flexible printed circuit board 22’, the conductive track line representing the material 27’ or being plated with the material 27’ or being covered with conductive glue. Thereby, it is possible to apply an electrical potential to the contact C4. Similarly, the cavity recess 24r1 ’ may partially expose another conductive track line routed within the flexible printed circuit board 22’, this other conductive track line representing the material 26’ or covered with conductive glue or being plated with the material 26’ comprising metal such that it is possible to apply an electrical potential to the contact C3.

[0097] The fill volume defined by the cavity 24’ may be at least partially filled by the high refractive index material 30’. In some illustrative examples herein, the dam structure 25’ may be formed of a thixotropic thermoset material as disclosed in aspects and embodiments of the disclosure above, e.g., a material comprising a thixotropic non-transparent epoxy material, e.g., black epoxy material, and / or a metallic binder component and / or a glass binder component.

[0098] As shown in Fig. 5, the cavity 24’ is completely filled with the high refractive index material 30’. However, this does not impose any limitation and a filling height may only partially fill the fill volume such that the LED 28’ is encapsulated, wherein a height of the LED 28’ is smaller than a height of the dam structure 25’. A filling of the filling volume may be to a height level within the cavity 24’ such that the connection line CLa is completely encapsulated by the high refractive index material 30’.

[0099] The LED 28’ is attached to the flexible printed circuit board 22’ by the material 26’. For example, the LED 28’ may be flip-chip bonded to the material 26’ or attached to the flexible printed circuit board 22’ via the material 26’ of conductive glue. In case of flip-chip bonding, a slot (not illustrated) may be formed in the cavity 24’ for separating anode (not illustrated) and cathode (not illustrated) contacts of the LED 28’ and to the LED 28’. However, this does not impose any limitation and any other attachment or chip bonding techniques may be employed.

[0100] With ongoing reference to Fig. 5, the electronic LED module 20’ still further comprises a high refractive index material 30’, the LED 28’ being encapsulated by the high refractive index material 30’. The high refractive index material 30’ may be formed directly on the LED 28’ such that the high refractive index material 30’ may be in mechanical contact with an LED die or chip of the LED 28’.

[0101] As described above, the high refractive index material 30’ completely fills the cavity 24’ and completely encapsulates the LED 28’. Referring to Fig. 5, the high refractive index material 30’ completely fills the cavity 24’ and a surface 30s’ of the high refractive index material 30’ facing away from the LED 28’ and the flexible printed circuit board 22’ is planar.

[0102] Although Fig. 5 shows the electronic LED module 20’ having single LED 28’ and single cavity 24’, this does not impose any limitation on the present disclosure and the electronic LED module 20’ may further comprise one or more additional cavities (not illustrated) formed in the surface 22s’ of the flexible printed circuit board 22’. One or more of additional cavities (not illustrated) may be equipped with at least one additional LED (not illustrated) in a manner similar to cavity 24’ being equipped with LED 28’.

[0103] Fig. 6 shows, in a schematic cross-sectional view, an electronic LED module 20”. The electronic LED module 20” may represent other illustrative examples of the electronic LED module 20 described above with respect to Fig. 4. Accordingly, similar reference numerals may indicate equal or similar technical features. In particular, the flexible printed circuit board 20” may be one of the single sided flexible printed circuit board FPCB-SS as described with respect to Fig. 9 and the double sided flexible printed circuit board FPCB-DS as described with respect to Fig. 10, similarly to the description to Fig. 2 to 5 in this respect. The disclosure above with respect to the single sided flexible printed circuit board FPCB-SS and the double sided flexible printed circuit board FPCB-DS is incorporated at this point in its entirety by reference. The electronic LED module 20” comprises a flexible printed circuit board 22” having a cavity 24” formed in a surface 22s” of the flexible printed circuit board 22”, and an LED 28” which is arranged within the cavity 24”. The cavity 24” is delimited on the surface 22s” of the flexible printed circuit board 22” by a dam structure 25”. The dam structure 25” defines a fill volume bordered by a surface region of the flexible printed circuit board 22”. The fill volume may completely cover the LED 28” (i.e., a height of the dam structure 25” is greater than a height level of the LED 28” or a depth of the cavity 24” is greater than a height of the LED 28”). Sidewalls 24s” of the cavity 24” are formed of inner sidewalls 24s1 ” of a recess 24r1 ” in the flexible printed circuit board 22”, inner sidewalls 24s3” of a recess 24r2” in the flexible printed circuit board 22”, and inner sidewalls 24s2” of the dam structure 25”. The surface region comprises a bottom 24b” of the recess 24r1 ” and a bottom 25” of the recess 24r2”.That is, the dam structure 25” completely encloses the surface region of the surface 22s”, the recesses 24r1 ” and 24r2” being completely formed within the surface region. The dam structure 25” is formed by a single layer of dam material representing a single dam ring completely surrounding the recesses 24r1 ” and 24r2”. The recesses 24r1 ” and 24r2” are formed adjacent to the cavity recess 24r1 ” separated therefrom by a surface portion 22s1 ” of the surface 22”.

[0104] The recess 24r1 ” is plated with metal comprising material 26” and the recess 24r2” is plated with metal comprising material 27” (which may be equal to the metal comprising material 26” or both materials may be different metal comprising materials). For example, only the bottom 25b” of the recess 24r2” may be covered with the material 27”. In some examples herein, the material 27” may comprise conductive glue or it may be formed of at least one of gold, silver, copper, and aluminum. However, this does not impose any limitation and inner sidewalls 25s” of the recess 24r2” may be at least partially covered with the material 27”. The LED 28” has a contact pad C5 formed thereon, the contact pad C5 being connected via a connection line CLb with a contact pad C6.

[0105] The recess 24r1 ” is partially covered with a material 26”. The material 26” may be a conductive component comprising material. The material 26” may be formed of conductive glue or of at least one of gold, silver, copper, and aluminum. However, this does not impose any limitation and inner sidewalls 24s1 ” of the recess 24r1 ” of the cavity 24” may be at least partially covered with the metal comprising material 26”. In case of the material 26” being a metal comprising material used for plating surfaces of the cavity 24”, light may be reflected by the sidewalls 24s1 ” of the recess 24r1 ” up to a level of plating on the sidewalls 24s1 ” of the recess 24r1 ”. In some illustrative examples, the recess 24r1 ” in the flexible printed circuit board 22” may partially expose a conductive track line routed within the flexible printed circuit board 22”, this conductive track line representing the metal comprising material 26”. Alternatively, the conductive track line may be plated with the metal comprising material 26”. Thereby, it is possible to apply an electrical potential to the LED 28”.

[0106] In some illustrative examples, the recess 24r2” may partially expose a conductive track line routed within the flexible printed circuit board 22”, the conductive track line representing the metal comprising material 27” or being plated with the metal comprising material 27”. Thereby, it is possible to apply an electrical potential to the contact C6. Similarly, the cavity recess 24r1 ” may partially expose another conductive track line routed within the flexible printed circuit board 22”, this other conductive track line representing the metal comprising material 26” or being plated with the metal comprising material 26” such that it is possible to apply an electrical potential to the contact C5.

[0107] The fill volume defined by the cavity 24” may be at least partially filled by the high refractive index material 30”. In some illustrative examples herein, the dam structure 25” may be formed of thixotropic nontransparent thermoset material, e.g., an epoxy material comprising a non-transparent epoxy material, e.g., a black epoxy material, and / or a metallic binder component and / or a glass binder component.

[0108] As shown in Fig. 6, the cavity 24” is completely filled with the high refractive index material 30”. However, this does not impose any limitation and a filling height may only partially fill the fill volume such that the LED 28” is encapsulated, wherein a height of the LED 28” is smaller than a height of the dam structure 25”. A filling of the filling volume may be to a height level within the cavity 24” such that the connection line CLb is completely encapsulated by the high refractive index material 30”.

[0109] The LED 28” is attached to the flexible printed circuit board 22” by attaching with or bonding to the material 26”. For example, the LED 28” may be attached via conductive glue of the material 26” or flip-chip bonded to the material 26”. In case of flip-chip bonding, a slot (not illustrated) may be formed in the cavity 24” for separating anode (not illustrated) and cathode (not illustrated) contacts of the LED 28” and to the LED 28”. However, this does not impose any limitation and any other chip attachment or bonding techniques may be employed.

[0110] With ongoing reference to Fig. 6, the electronic LED module 20” still further comprises a high refractive index material 30”, the LED 28” being encapsulated by the high refractive index material 30”. The high refractive index material 30” may be formed directly on the LED 28” such that the high refractive index material 30” may be in mechanical contact with an LED die or chip of the LED 28”.

[0111] As described above, the high refractive index material 30” completely fills the cavity 24” and completely encapsulates the LED 28”. Referring to Fig. 6, the high refractive index material 30” completely fills the cavity 24” and a surface 30s” of the high refractive index material 30” facing away from the LED 28” and the flexible printed circuit board 22” is convex.

[0112] Although Fig. 6 shows the electronic LED module 20” having single LED 28” and single cavity 24”, this does not impose any limitation on the present disclosure and the electronic LED module 20” may further comprise one or more additional cavities (not illustrated) formed in the surface 22s” of the flexible printed circuit board 22”. One or more of additional cavities (not illustrated) may be equipped with at least one additional LED (not illustrated) in a manner similar to cavity 24” being equipped with LED 28”.

[0113] Although Fig. 6 shows the surface 30s” of the high refractive index material 30” having a convex shape, this does not impose any limitation on the present disclosure and the high refractive index material 30” may have at least one of an at least partially convex and at least partially concave and at least partially planar shaped upper surface facing away from the LED 28”. Accordingly, the high refractive index material 30” may be shaped for implementing an optical component with a desired optical effect, e.g., a converging or collimating or dispersing or diffracting effect or a combination thereof.

[0114] Fig. 7 shows, in a schematic cross-sectional view, an electronic LED module 40 comprising a flexible printed circuit board 42 having a cavity 44 formed in a surface 42s of the flexible printed circuit board 42, the cavity 44 being delimited on the surface 42s of the flexible printed circuit board 42 by a dam structure 45 formed of at least a first dam 45a and a second dam 45b. The dam structure 45 defines a fill volume bordered by a surface region, i.e. , the surface region comprising a bottom 44b of the cavity 44, and sidewalls 24s of the cavity 24. The sidewalls 24s of the cavity 24 are formed of inner sidewalls 24s1 of a recess 44r in the flexible printed circuit board 42, and inner sidewalls 44s2 and 44s3 of the dam structure 45. The dam structure 45 completely encloses the surface region of the surface 42s, the cavity 44 being completely formed within the surface region, the dam structure 45 being formed by plural layers of dam material representing the first dam 45a and the second dam 45b formed in a stacked arrangement as a stacking ring completely surrounding the recess 44r. The fill volume defined by the cavity 44 may be at least partially filled by the high refractive index material 50. In some illustrative examples herein, the dam structure 45 may be formed of a thixotropic nontransparent thermoset material, e.g., an epoxy material comprising a thixotropic nontransparent epoxy material, e.g., black epoxy material, and / or a metallic binder component and / or a glass binder component.

[0115] The cavity 44 is partially covered with a material 46. The material 46 may be a conductive component comprising material. As shown in Fig. 7, a bottom 44b of the cavity 44 is covered with the material 46. The material 46 may be a conductive glue or it may be formed of at least one of gold, silver, copper, and aluminum. However, this does not impose any limitation and inner sidewalls 44s1 of the recess 44r of the cavity 44 may be at least partially covered with the material 46. In case of the material 46’ being a metal comprising material used for plating inner surfaces of the cavity 44, light may be reflected by the sidewalls 44s1 of the recess 44r up to a level of plating on the sidewalls 44s1 of the recess 44r.

[0116] In some illustrative examples, the cavity 44, i.e. , the recess 44r in the flexible printed circuit board 42, may partially expose a conductive track line routed within the flexible printed circuit board 42, this conductive track line representing the material 46. Alternatively, the conductive track line may be plated with the material 46 in case of the material 46 being a metal or the material 46 may be a conductive glue deposited onto the conductive track line. Thereby, it is possible to apply an electrical potential to the LED 48.

[0117] The electronic LED module 40 further comprises an LED 48 which is arranged within the cavity 44. The fill volume may completely cover the LED 48 (i.e., a height of the dam structure 45 is greater than a height level of the LED 48 or a depth of the cavity 44 is greater than a height of the LED 48). The dam structure 45 adjusts a sufficient depth for the cavity 44 such that the depth of the cavity 44 is greater than a height of the LED 48, although the first dam 45a may not have a sufficient height for providing a recess of sufficient depth relative to the LED 48. Depending on a desired depth of the cavity 44, the dam structure 45 may comprise at least one dam in addition to the first and second dams 45a and 45b.

[0118] As shown in Fig. 7, the cavity 44 is completely filled with the high refractive index material 50. However, this does not impose any limitation and a filling height may only partially fill the fill volume such that the LED 48 is encapsulated, wherein a height of the LED 48 is smaller than a height of the dam structure 45. The LED 48 is attached to the flexible printed circuit board 42 by attaching with or bonding to the material 46. For example, the LED 48 may be attached via conductive glue or flip-chip bonded to material 46. In case of flip-chip bonding, a slot (not illustrated) may be formed in the cavity 44 for separating anode (not illustrated) and cathode (not illustrated) contacts of the LED 48 and to the LED 48. However, this does not impose any limitation and any other chip attachment or bonding techniques may be employed.

[0119] With ongoing reference to Fig. 7, the electronic LED module 40 still further comprises a high refractive index material 50, the LED 48 being encapsulated by the high refractive index material 50. The high refractive index material 50 may be formed directly on the LED 48 such that the high refractive index material 50 may be in mechanical contact with an LED die or chip of the LED 48.

[0120] As described above, the high refractive index material 50 completely fills the cavity 44 and completely encapsulates the LED 48. Referring to Fig. 7, the high refractive index material 50 completely fills the cavity 44 and a surface 50s of the high refractive index material 50 facing away from the LED 48 and the flexible printed circuit board 42 is convexly shaped. The high refractive index material 50 may implement a collimating optical element resulting from an appropriately shape of the surface 50s of the high refractive index material 50. The high refractive index material 50 may be a self-doming material as described in the context of the first aspect of the disclosure as described above.

[0121] Although Fig. 7 shows the electronic LED module 40 having single LED 48 and single cavity 44, this does not impose any limitation on the present disclosure and the electronic LED module 40 may further comprise one or more additional cavities (not illustrated) formed in the surface 42s of the flexible printed circuit board 42. One or more of additional cavities (not illustrated) may be equipped with at least one additional LED (not illustrated) in a manner similar to cavity 44 being equipped with LED 48.

[0122] With ongoing reference to Fig. 7, the high refractive index material 50 may cover a surface region of the surface 42s of at least the size of the cavity 44. Accordingly, a shaping of the surface 50s of the high refractive index material 50 may be obtained by the high refractive index material 50 having direct mechanical contact with the material 46 and / or by directly contacting the surface 42s of the flexible printed circuit board 42.

[0123] Although Fig. 7 shows the surface 50s of the high refractive index material 50 having a convex shape, this does not impose any limitation on the present disclosure and the high refractive index material 50 may have at least one of an at least partially convex and at least partially concave and at least partially planar shaped upper surface facing away from the LED 48. Accordingly, the high refractive index material 50 may be shaped for implementing an optical component with a desired optical effect, e.g., a converging or collimating or dispersing or diffracting effect or a combination thereof.

[0124] Referring to Fig. 8, a possible but non-limiting implementation of a sensor device in accordance with the second aspect described above, is shown in a schematic cross-sectional view.

[0125] Fig. 8 shows a sensor device 60, e.g., an oxygen sensor device. The sensor device 60 comprises a casing 62 housing an electronic LED module 64 with light sources L1 and L2, and a photodetector 66 configured for detecting light emitted by the light sources L1 and L2. The electronic LED module 64 may be the electronic LED module according to the first aspect as described above. That is, the electronic LED module 64 may be one of the electronic LED modules as described above with respect to one of Fig. 1 to 7.

[0126] The casing 62 may be a metal casing or a flexible bandage configured for accommodating a finger F of a user of the sensor device 60. However, the casing 62 may be embodied such that another body part of a user of the sensor device 60 may be arranged within the casing 62 such that the photodetector 66 is arranged and configured for detecting light emitted from the electronic LED module 64 during operation of the sensor device 60.

[0127] In summary, the present disclosure provides for an electronic LED module, comprising: a flexible printed circuit board having at least one cavity formed in a surface of the flexible printed circuit board, inner surfaces of the at least one cavity being at least partially covered with a conductive component comprising material; at least one LED arranged within the at least one cavity of the flexible printed circuit board and attached to the flexible printed circuit board; and a dam structure formed in the surface of the flexible printed circuit board. Herein, the dam structure completely encloses a surface region of the surface, the cavity being completely formed within the surface region, wherein the at least one LED is encapsulated by a high refractive index material.

[0128] For example, the conductive component may comprise a material which may be a conductive glue (e.g., at least one of silver, nickel, copper and graphite) or a metal (e.g., at least one of silver, nickel, copper, gold etc.) comprising material suitable for plating such that the cavity may be at least partially plated with the metal comprising material, depending on whether the LED is attached by soldering or conductive glue (e.g., as shown in Fig. 8 and 9 of the present application). For example, the LED may be mounted within the cavity, e.g. via solder pads within the cavity and contacting plated interior sur-face regions of the cavity (e.g., a bottom region of the cavity) and / or gluing. A glue may be an electrically non-conductive glue in case of solder attachment, while the glue may be an electrically conductive glue in case of attached to the cavity by electrically conductive die attach via an adhesive layer on a bottom of the cavity.

[0129] For example, the high refractive index material may be a material having a refractive index of at least 1 .2. In explicitly disclosed examples herein, the high refractive index material may be a silicon material having such a high refractive index, preferably a silicon material for use as an encapsulant of LED devices, e.g., the silicon material possibly being a thixotropic silicon material which may be deposited and solidify after deposition without further curing, or, alternatively, the silicon material possibly being a curable silicon material allowing deposition and curing after deposition.

[0130] For example, the dam structure may be a dam structure having a single dam (c.f. elements 25, 25’, 25” in Fig. 4 to 6) or plural dams (c.f. elements in form of first and second dams 45a, 45b in Fig. 7 - not excluding at least one additional dam in addition to first and second dams 45a, 45b). The effect of the dam structure may allow to advantageously delimit the surface region which is to be filled by high refractive index material and avoid lateral loss by the dam structure.

[0131] In some specific examples, the dam structure may be formed by a material with thixotropy allowing to deposit the dam structure while providing a solid dam structure after deposition. The material of the dam structure may be a nontransparent thermoset material, optionally having at least one of a metallic binder component and a glass binder component included therein. This may have the effect of avoiding lateral loss and, possibly adjusting a reflectivity of the dam structure by inclusion of metallic and / or glass components.

[0132] In some special illustrative but non-limiting examples herein, the dam structure may be a thixotropic nontransparent material, e.g., black, thixotropic epoxy. The dam structure may dispense as a self-supporting structure and cure into a rigid barrier. In case of being black (e.g., when using a black epoxy material), the dam structure may further suppresses lateral light which could interfere with a sensor’s sensing efficiency. If it is desired to recycle sideway light back toward a sensor’s detector, the very same dam structure can be turned into a reflector simply by dispersing microscopic “mirrors” in the thermoset material. Herein, the dam structure may be formed of a nontransparent thermoset material and at least one of a metallic (binder) component and a glass (binder) component, wherein the metallic (binder) component may be a metallic flake and / or the glass (binder) component may be a glass bead (uncoated glass bead or a metal coated glass bead). These examples will be described in greater detail with respect to first to third examples below. In a first example herein may be mirrors given by thin metal surfaces. Herein, a few volume-percent of aluminium or silverflakes, e.g. five-to-twenty micrometres in diameter, may be added, each flake representing a specular reflector bouncing light, e.g., red and near-infra-red light, with efficiencies well above ninety per cent. When imposing shear forces during dispensing, most flakes may be made to lie parallel to a substrate, so a narrow mirrored ring may form along the dam structure’s inner wall, thereby reflecting stray light back into the high refractive index material.

[0133] In a second example herein, metal may be alternatively or additionally introduced as a nanometre- thin coating on a glass bead, such as a glass microspheres. These coated glass beads (e.g., platelets, microspheres, bubbles or rods), may also behave half as mirrors and half as diffuse scatterers such that, when a photon meets a coated bead, it changes direction and re-enters the optically active zone instead of escaping sideways. When providing hollow glass microspheres with hollow glass core (air core of filled with material of low optical density and / or refractive index), quite high loadings — up to roughly twenty volume-percent — can be reached without making the dam material too viscous to print or jet during deposition.

[0134] If only a modest boost is desired, uncoated beads of high-index glass, such as rich in barium or titania, can be employed, such uncoated beads having a refractive index near two which may be sufficient to drive strong Mie scattering at pulse-oximeter wavelengths, allowing lengthening of optical paths without introducing any metallic species, thereby avoiding metal material which poses the risk of metal migration or corrosion.

[0135] In a third example herein, a black epoxy resin may be employed, however the dam structure still reflecting a surprising amount of near-infra-red. The skilled person will appreciate that certain complex-oxide “cool-black” pigments absorb across the visible spectrum, so the dam structure may appear black in the optical visible light range, but becomes transparent or reflective above about seven hundred nanometers. A fraction of a weight-percent of such pigment may be mixed with ordinary carbon black, allowing to tune visible darkness and near-IR reflectance almost independently.

[0136] Independent of any filler chosen as a high refractive index material, glass beads may be prepared with good bonding characteristics after being subjected to a silane treatment.

[0137] An illustrative but non-limiting example recipe is provided with prototyping batch of 100 g total:

[0138] Component Amount

[0139] Bis-F epoxy resin 48 g Anhydride hardener 28 g

[0140] Fumed silica (6 pm) 4 g

[0141] Carbon black 0.3 g

[0142] Al-coated solid glass microspheres, D50 » 35 pm 18 g

[0143] 2-phenylimidazole accelerator 0.2 g y-GPS silane (on beads) 0.5 wt % to beads

[0144] In the recipe, the components above are mixed under vacuum planetary shear, 200 pm-high bead are dispensed as dam. B-stage 110 °C / 5 min and final cure 150 °C / 1 h.

[0145] Result: reflectance (total hemispherical) of the dam’s inner wall rises from 6 % — > 28 % at 660 nm and 4 % — > 34 % at 940 nm, matching the 20-30 % MIR gain reported for Al-coated glass fillers in polymers .

[0146] The following Table 1 summarizes different recipes which are disclosed herein:

[0147] Strategy addition to dam material Typical loading Notes for a dam bead

[0148] Shear during dispensing makes flakes lie parallel to the

[0149] Al, Ag or Au flakes (5-20 gm,

[0150] Specular metal flakes 2-10 vol % board; gives a “mirror band” on the inner wall. Couple aspect > 50) with fumed-silica to keep thixotropy.

[0151] Silver- or aluminium-plated Hollow spheres keep weight and viscosity down; the

[0152] Metal-coated glass hollow / solid glass beads (20-70 10-25 vol % Ag / Al skin gives high IR reflectance while the carbon- microspheres gm) black in the resin keeps the dam looking black.

[0153] Uncoated high-index Barium- or titania-rich glass Useful when you need only a mild boost and want to avoid glass beads beads or platelets metal migration. IR-reflective “coolSpinel blacks or Zn-doped Can be blended with carbon black to tune visible darkness black” pigments Ca2MnO4 independently of NIR reflectance.

[0154] Silver-coated and TiCh-primed Combines low density, good thixotropy and chemical sta¬

[0155] Hybrid fillers 15-20 vol % glass bubbles bility.

[0156] Table 1

Claims

Claims1 . An electronic LED module, comprising: a flexible printed circuit board having at least one cavity formed in a surface of the flexible printed circuit board, inner surfaces of the at least one cavity being at least partially covered with a conductive component comprising material; and at least one LED arranged within the at least one cavity of the flexible printed circuit board and attached to the flexible printed circuit board, a dam structure formed in the surface of the flexible printed circuit board, wherein the dam structure completely encloses a surface region of the surface, the cavity being completely formed within the surface region, wherein the at least one LED is encapsulated by a high refractive index material.

2. The electronic LED module of claim 1 , wherein the high refractive index material has a first surface in contact with the flexible printed circuit board and a second surface facing away from the cavity, the second surface being at least partially a curved surface.

3. The electronic LED module of claim 2, wherein the high refractive index material completely fills the cavity and the curved surface is completely outside of the at least one cavity.

4. The electronic LED module of claim 2 or 3, wherein the second surface of the high refractive index material is convexly shaped.

5. The electronic LED module of one of claims 1 to 4, wherein the dam structure defines a fill volume bordered by the surface region of the flexible printed circuit board, the fill volume being at least partially filled by the high refractive index material and / or the fill volume completely covering the at least one LED.

6. The electronic LED module of one of claims 1 to 5, wherein the dam structure is formed of a nontransparent thermoset material and / or a metallic binder component and / or a glass binder component.

7. The electronic LED module of one of claims 1 to 5, wherein the dam structure is formed of a nontransparent thermoset material and at least one of a metallic component and a glass component.

8. The electronic LED module of claim 7, wherein the metallic component is a metallic flake.

9. The electronic LED module of one of claims 6 to 8, wherein the glass component is a glass bead.

10. The electronic LED module of claim 9, wherein the glass bead is coated with a metal.11 . The electronic LED module of one of claims 6 to 10, wherein the nontransparent thermoset material is a black thermoset material, such as black epoxy material.

12. The electronic LED module of one of claims 6 to 11 , wherein the metallic component comprises at least one of Al, Ag or Au flakes.

13. The electronic LED module of claim 12, wherein flakes have sizes in a range of about 5 to about 20 pm and / or aspect ratios > 50.

14. The electronic LED module of one of claims 6 to 13, wherein the glass component comprises metal coated hollow glass beads and / or metal coated solid glass beads or platelets.

15. The electronic LED module of one of claims 1 to 14, wherein the dam structure comprises a single layer of dam material or a stack of at least two layers of dam material.

16. The electronic LED module of one of claims 1 to 15, wherein the at least one LED is an LED die and the high refractive index material is in direct contact with the LED die.

17. A sensor device, comprising: the electronic LED module of one of claims 1 to 16; a photodetector; and a casing housing the electronic LED module and the photodetector, wherein the photodetector is arranged and configured for detecting light emitted from the electronic LED module during operation of the sensor device.

18. The sensor device of claim 17, wherein the sensor device is an oximeter sensor device.

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