WO2022090035A1

WO2022090035A1 - Insulating metal pcb with light-blocking layer

Info

Publication number: WO2022090035A1
Application number: PCT/EP2021/079125
Authority: WO
Inventors: Grigory Alexandrovich ONUSHKIN; Peter Henri BANCKEN
Original assignee: Signify Holding B.V.
Priority date: 2020-10-29
Filing date: 2021-10-20
Publication date: 2022-05-05

Abstract

The invention provides a system (1000) comprising a printed circuit board (500) and a light source (100), functionally coupled to the printed circuit board (500), wherein the light source (100) is configured to generate light (101), wherein the printed circuit board (500) comprises a stack of layers (509), wherein at least at a first part (501) of the printed circuit board (500) the stack of layers (509) comprises at least part of a first layer element (510), at least part of a second layer element (520), at least part of a third layer element (530), at least part of a fourth layer element (540), and at least part of a fifth layer element (550), wherein: (a) the first layer element (510) comprises a first layer (511), wherein the first layer (511) comprises a metal layer; (b) the second layer element (520) is configured in contact with at least part of the first layer element (510), wherein the second layer element (520) comprises a second layer (521), wherein the second layer (521) is an electrically insulating layer (521); (c) the third layer element (530) is configured in contact with at least part of the second layer element (520), wherein the third layer element (530) is configured without contact with the first layer (511), wherein the third layer element (530) comprises a third layer (531), wherein the third layer (531) is configured to reflect and/or absorb light (101) having a first wavelength; (d) the fourth layer element (540) is configured in contact with at least part of the third layer element (530), wherein the fourth layer element (540) comprises a fourth layer (541), wherein the fourth layer (541) is an electrically insulating layer (521); (e) the fifth layer element (550) is configured in contact with at least part of the fourth layer element (540), wherein the fifth layer element (550) comprises a fifth layer (551), wherein the fifth layer (551) is electrically conductive, wherein the fifth layer (551) is configured without contact with the first layer (511).

Description

Insulating metal PCB with light-blocking layer

FIELD OF THE INVENTION

The invention relates to a system comprising a printed circuit board, wherein the system in embodiments further comprises a light source, such as a solid state light source. The invention further provides a light generating device comprising such system.

BACKGROUND OF THE INVENTION

An insulation film coated and formed as a protective film in a printed-wiring board is known in the art. US2009/0141505 indicates in relation to such film that in addition to characteristics such as solvent resistance, hardness, solder resistance and electrical insulating properties generally required in a solder resist film, an excellent light reflectivity capable of utilizing emission of LED effectively has been desired. US2009/0141505 describes e.g. a white heat-hardening resin composition comprising rutile-type titanium oxide; and a heat-hardening resin.

EP2927971 Al discloses a mounting substrate and light emitting apparatus using the mounting substrate. To provide a mounting substrate wherein insulation resistance of a metal substrate having an oxide film formed on the surface thereof is ensured, and light reflectance is improved by preventing a light-reflecting material contained in a reflection layer from diffusing into a surface of the metal substrate. A mounting substrate includes a metal substrate, and a surface layer section formed on an upper surface of the metal substrate. The surface layer section includes an oxide film layer formed on a surface of the metal substrate, a barrier layer formed on the oxide film layer, a reflection layer formed on the barrier layer and containing a light-reflecting material, and a protection film layer formed on the reflection layer.

US2017/317250 discloses a substrate having dielectric strength and light reflectivity, as well as excellent mass productivity. A substrate for mounting a light-emitting element thereon includes a base and an insulation layer disposed directly or indirectly on a surface of the base. The insulation layer includes a reflection layer that reflects light and a mesh glass sheet that is disposed within the reflection layer and that has a coefficient of linear expansion smaller than that of the reflection layer. SUMMARY OF THE INVENTION

Chip scale packaged (CSP) LEDs are being increasingly used in various applications because of its robust structure and attractive pricing. As opposed to the packaged LEDs, a CSP LED is placed directly on top of the printed circuit board (PCB). In the case of packaged LEDs, the presence of the package may stop blue light reaching the PCB. In the case CSP high intensity light from the CSP may reach the surface of the PCB. PCBs with high thermal conductivity have a metal (aluminum) base with an epoxy dielectric layer on top it below the copper tracks. During the operation of the CSP LEDs (blue) light from the LEDs may fall onto the PCB. Light may go through the solder resist layer and reach a dielectric layer. By the high intensity light, both solder resist layer and the dielectric layer may degrade. As a result of degrading dielectric layer, short circuiting between the metal substrate and the copper tracks may take place.

Hence, it is an aspect of the invention to provide an alternative lighting system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

In a first aspect, the invention provides a system comprising a printed circuit board. Especially, the printed circuit board comprises a stack of layers. In embodiments, at least at a first part of the printed circuit board the stack of layers may comprise at least part of a first layer element, at least part of a second layer element, at least part of a third layer element, at least part of a fourth layer element, and at least part of a fifth layer element. In specific embodiments, the first layer element may comprise a first layer. Especially, in embodiments the first layer may comprise a metal layer. Further, in specific embodiments, the second layer element may especially be configured in contact with at least part of the first layer element. Especially, in embodiments the second layer element may comprise a second layer. In specific embodiments, the second layer is an electrically insulating layer. Further, in embodiments the third layer element may especially be configured in contact with at least part of the second layer element. Especially, in embodiments the third layer element may especially be configured without contact with the first layer. Yet further, in embodiments the third layer element may comprise a third layer. Especially, in embodiments the third layer may especially be configured to reflect and/or absorb light having a first wavelength. Further, in embodiments the fourth layer element may especially be configured in contact with at least part of the third layer element. Especially, in embodiments the fourth layer element may comprise a fourth layer. Further, in embodiments the fourth layer may especially be an electrically insulating layer. Further, in embodiments the fifth layer element may especially be configured in contact with at least part of the fourth layer element. Especially, in embodiments the fifth layer element may comprise a fifth layer. Further, in embodiments the fifth layer may be electrically conductive. Especially, in embodiments the fifth layer may especially be configured without (electrically conductive) contact with the first layer. Yet further, especially in embodiments the system may further comprise a light source functionally coupled to the printed circuit board. Especially, the light source may be configured to generate light. Further, especially the light source may be a solid state light source, such as a CSP LED. The light source may in embodiments be functionally coupled to two first parts. Therefore, especially the invention provides a system comprising a printed circuit board, and optionally a light source, wherein the printed circuit board may comprise a stack of layers, wherein at least at a first part of the printed circuit board the stack of layers may comprise at least part of a first layer element, at least part of a second layer element, at least part of a third layer element, at least part of a fourth layer element, and at least part of a fifth layer element, wherein: (i) the first layer element may comprise a first layer, wherein the first layer may comprise a metal layer; (ii) the second layer element may especially be configured in contact with at least part of the first layer element, wherein the second layer element may comprise a second layer, wherein the second layer is an electrically insulating layer; (iii) the third layer element may especially be configured in contact with at least part of the second layer element, wherein the third layer element may especially be configured without contact with the first layer, wherein the third layer element may comprise a third layer, wherein the third layer may especially be configured to reflect and/or absorb light having a first wavelength; (iv) the fourth layer element may especially be configured in contact with at least part of the third layer element, wherein the fourth layer element may comprise a fourth layer, wherein the fourth layer is an electrically insulating layer; (v) the fifth layer element may especially be configured in contact with at least part of the fourth layer element, wherein the fifth layer element may comprise a fifth layer, wherein the fifth layer is electrically conductive, wherein the fifth layer may especially be configured without (electrically conductive) contact with the first layer. In embodiments, wherein the system comprises the light source, especially the light source may be functionally coupled to the printed circuit board. Further, as indicated above the light source may especially be configured to generate light. With such system, the first layer element, which may e.g. comprise a metal layer, may not get into electrical contact with e.g. copper tracks (as embodiment of a fifth layer) or may not easily be exposed to the external at the side of the (other) layers, as the third layer element, especially the third layer, may protect this second layer element. Especially, it may be desirable that the first layer (such as an Al-base) is not exposed to electrically conductive fifth layer with a too small air gap distance between them. This could cause too low voltage electrical air-breakdown once distance is getting too small e.g. due to cracking of dielectric layer between them. Especially, would e.g. light from the light source reach the third layer, e.g. when other layers located between third layer and light-source would be damaged, such as cracked, light may essentially not further damage the second layer element, which may increase risks, as the first layer element (and the second layer element) is protected by the third layer, which may absorb or reflect at least part of the (light source) light. In embodiments, a minimal breakdown voltage may be Vbr = 2*Udc+1000VAC, where Ude is a nominal line to neutral voltage of the LED module. Especially, the third layer may available close to the light source, and may not necessarily be available over the entire multi-layer.

As indicated above, the system may comprise a printed circuit board (PCB) and optionally a light source. Especially, the system comprises the printed circuit board and the light source(s) functionally coupled to the PCB.

Hence, the term “system” may refer to a PCB as such (such as described herein), to a PCB with a functional component, such as a light source, and to such PCB and the light source functionally coupled thereto. Elements of the system are described in more detail below.

Especially, the board may comprise one or more of a CEM-1 PCE, a CEM-3 PCE, a FR-1 PCE, a FR-2 PCB, a FR-3 PCB, a FR-4 PCB, and aluminum metal core PCB, especially one or more of a CEM-1 PCB, a CEM-3 PCB, a FR-1 PCB, and a FR4 PCB and an aluminum metal core PCB, more especially one or more of a CEM-1 PCB, a CEM-3 PCB, a FR-1 PCB. Especially, the PCB comprises a metal core PCB. Therefore, in embodiments the printed circuit board comprises a thermally conductive material, such as aluminum. Printed circuit boards comprising a metal core may also be indicated as insulated metal substrate (IMS).

The printed circuit board may comprise a plurality of layer elements. The term “layer element” may refer to a single layer or to a plurality of layers. Essentially all layers describe herein are comprised by a stack or laminate. Hence, the PCB may comprise a stack (or laminate) of layers. This stack may also be indicated as “PCB stack”. The number of layers and type of layers may vary over the PCB. Basically, in embodiments the PCB may comprise over its entire length and width a (PCB) stack of layers comprising the first layer element and the second layer element.

At positions at the PCB where electrically conductive tracks are available, the PCB stack may comprise the first layer element, the second layer element, and the fifth layer element. Hence, the second layer element may be in (physical) contact with the first layer element and the fifth layer element.

In general, except where electrical contact with a functional component with the fifth layer element is available, the fifth layer element may in embodiments be covered with the sixth layer element. Hence, especially at the PCB where electrically conductive tracks are available, the PCB stack may comprise the first layer element, the second layer element, the fifth layer element (comprising the electrically conductive track(s)), and the sixth layer element. As indicated above, at one or more (sixth) parts of the printed circuit board the second layer element may be in contact with the first layer element and the fifth layer element, and the fifth layer element may be in contact with the sixth layer element.

Herein, the term “contact” or “in contact”, and similar terms, may especially refer in embodiments to physical contact. For instance, the layers or layer elements that are in contact may adhere to each other, as known in the art of e.g. PCBs. Instead of the term “electrical contact”, and similar terms, also the terms “electrical conductive contact” or “electrically conductive contact”, and similar terms, may be sued.

Hence, at different positions or parts of the printed circuit board, different stack configurations may be available. Further, two or more of such stack configurations at different positions or parts of the printed circuit board may share a layer element, and may thus each comprise part of a layer element.

Hence, in specific embodiments the system may comprise a printed circuit board wherein the printed circuit board especially comprises a stack of layers, wherein at least at a first part of the printed circuit board the stack of layers may comprise at least part of a first layer element, at least part of a second layer element, at least part of a third layer element, at least part of a fourth layer element, and at least part of a fifth layer element. As indicated above, at a second part or further part of the printed circuit board, a different stack composition may be available, though in general over the entire printed circuit board the stack may (thus) comprise at least the first layer element and the second layer element. The system may comprise one or more, in general at least two, first parts (see also below).

The layer elements are further discussed below in more detail.

An electrically conductive element may comprise, or essentially consist of electrically conductive material. An electrically insulating element may comprise, or essentially consist of electrically insulating material. Herein, in embodiments a conductive material may especially comprise a conductivity (at room temperature) of at least T10⁵ S/m, such as at least T10⁶ S/m. Herein, a conductivity of an insulated material may especially be equal to or smaller than 1-1O'¹⁰ S/m, especially equal to or smaller than T10'¹³ S/m. Herein a ratio of an electrical conductivity of an isolating material (insulator) and an electrical conductivity of an electrically conductive material (conductor) may especially be selected smaller than 1 • 10‘¹⁵.

An electrically conductive contact may refer to a (physical) contact between two (or more) electrically conductive elements, such as two electrically conductive layers. When in such embodiments the electrical conductivity of the arrangement of the two conductive elements measured over the two conductive elements be at least T10⁶ S/m, then there is electrically conductive contact. It may also refer in specific embodiments to an arrangement of two (or more) electrically conductive elements with a medium in between. When in such embodiments the electrical conductivity of the arrangement of the two conductive elements measured over the two conductive elements with the medium in between, be at least T10⁶ S/m, then there is also electrically conductive contact.

In specific embodiments, a resistivity of a dielectric layer may be at least about 1 M0hm*cm.

The first layer element may comprise a first layer. Especially, the first layer may comprise a metal layer. For instance, in embodiments the metal layer may be an aluminum layer. Instead of (or in addition to) aluminum, the metal layer may comprise a copper layer. For instance, in embodiments the metal layer may be a copper layer. Other solutions may also be possible, like stainless steel, other metals, or (their) metal alloys. Especially, the first layer may comprise a metal core of the printed circuit board. Especially, the first layer element may be available over essentially the entire printed circuit board. Hence, the first layer element may provide a support function. Further, the first layer may have a thermal dissipation function and/or a thermal spread function. The first layer (or support layer) may have a thickness selected from the range of 20 pm - 10 mm, sch as at least 30 pm, like in embodiments selected from the range of about 100 pm - 10 mm.

The first layer element may have a first side and a second side. In embodiments, at least part of the first side may in embodiments be directed to the second layer element. More especially, in embodiments at least part of the first side of the first layer element may be in contact with at least part of a second side (see also below) of the second layer element.

The first layer element may comprise in embodiments also one or more other layers. In specific embodiments, the first layer element may comprise at the second side an insulating layer. Hence, in specific embodiments the stack may comprise an additional insulating layer on the back side of the first layer, such as an aluminum base (of an IMS PCB). Such insulating layer may in embodiments be comprised by the first layer element, wherein the first layer is in specific embodiments sandwiched by the insulating layer on the back side of the first layer and the second layer element. For instance, in embodiments a well-known dielectric layer may be provided.

The second layer element may especially be configured in contact with at least part of the first layer element.

In embodiments, part of the second layer element may especially be configured in contact with part of the fourth layer element. In embodiments, the part of the second layer which may be in contact with part of the fourth layer element may have a surface area of at least 10% of the total surface area (of a major surface) of the PCB, preferably at least 15%, more preferably at least 18%, most preferably at least 20%. In embodiments, the part of the second layer which may not be in contact with part of the fourth layer element may have a surface area of at least 10% of the total surface area (of a major surface) of the PCB, preferably at least 15%, more preferably at least 18%, most preferably at least 20%. In embodiments, the part of the fourth layer which may not be in contact with part of the second layer element may have a surface area of at least 10% of the total surface area (of a major surface) of the PCB, preferably at least 15%, more preferably at least 18%, most preferably at least 20%.

In embodiments, the surface area of the third layer element may be at least 10% of the total surface area (of a major surface) of the PCB, preferably at least 15%, more preferably at least 18%, most preferably at least 20%. In embodiments, the surface area of the third layer element may be less than 90% of the total surface area (of a major surface) of the PCB, preferably less than 85%, more preferably less than 82%, most preferably less than 80%.

The surface area (in other words coverage) of the third layer may be very important. It is desired to arrange the third layer only at a location or locations where it is essential to block high density of (blue and/or UV) light emission originated from the (LED) light source(s) e.g. CSP LED(s). If such layer will have too big size and/or cover a too broad area under the fifth layer (i.e. the electrical circuit e.g. Cu electrodes), this could cause additional high risk of electrical breakdown and/or unwanted short-circuit connection between different fifth layer elements / (upper) (Cu) electrodes via the third layer (elements) (e.g. underlying electrically conductive / metal layer). This means that the third layer (elements) should preferably only located directly under the (LED) light source(s) and/or a small area around the (LED) light source(s).

The second layer element may have a first side and a second side. In embodiments, at least part of the first side may in embodiments be directed to the third layer element. More especially, in embodiments at least part of the first side of the second layer element may be in contact with at least part of a second side (see also below) of the third layer element. Further, especially at least part of the second side of the second layer element may be in contact with at least part of the first side of the first layer element.

The second layer element may comprise a second layer. Especially, the second layer is an electrically insulating layer. For instance, in embodiments a well-known dielectric layer may be provided. In specific embodiments, the second layer may comprise an epoxy layer. In yet further specific embodiments, the second layer may comprise an epoxy layer hosting alumina particles and/or titania particles. Other solutions to reflect (or absorb light), like reflective flakes, etc., may also be possible.

Especially, the second layer element may be configured to provide an electrical isolation between the first layer and the fifth layer. As indicated above, especially the second layer may comprise a dielectric layer.

The second layer may have a thickness selected from the range of 20-250 pm, such as 50-150 pm.

The third layer element may especially be configured in contact with at least part of the second layer element.

The third layer element may have a first side and a second side. In embodiments, at least part of the first side may in embodiments be directed to the fourth layer element. More especially, in embodiments at least part of the first side of the third layer element may be in contact with at least part of a second side (see also below) of the fourth layer element. Further, especially at least part of the second side of the third layer element may be in contact with at least part of the first side of the second layer element.

The third layer element may have a first side and a second side. In embodiments, (at least part ol) the first side of the third layer element may be in contact with part of a second side of the fourth layer element. Further, especially (at least part ol) the second side of the third layer element may be in contact with part of the first side of the second layer element.

The third layer element may especially be configured without contact with the first layer. Especially, this may be the case in embodiments wherein the third layer element comprises a metal or other electrically conductive material. Hence, in embodiments wherein the third layer element comprises an electrically conductive layer, the third layer element may be configured electrically insulated from the first layer.

Therefore, in specific embodiments the third layer may comprise a metal layer, and the third layer may be configured without (electrically conductive) contact with the first layer and the fifth layer (see also below). In embodiments, the third layer may be an aluminum layer. Alternatively or additionally, in embodiments the third layer may be a copper layer.

Especially, the third layer element is sandwiched between the second layer element and the fourth layer element or other layer element. Note that the third layer element may not necessarily be available over the entire printed circuit board. In contrast, in embodiments the third layer element may essentially only available in the vicinity of a light source (see further below).

The third layer element may comprise a third layer. Especially, in embodiments the third layer may be configured to reflect and/or absorb light having a first wavelength. In general, for the third layer may apply that the percentage of reflection is larger than the percentage of absorption in the case of a reflective layer and the percentage of absorption may be larger than the percentage of reflection in the case of an absorbing layer. Would light reach the third layer, at least 50%, such as at least 60%, like at least 70% of the light may be reflected or absorbed. Here, the percentages refer to (spectral) power (in Watt). In embodiments, the third layer is configured such that would light reach the third layer, essentially no light reaches the second layer element downstream of the third layer. This may be achieved essentially full reflection, essentially full absorption, or a combination of absorption and reflection, wherein absorption may be about 100-x%, and reflection may be about x%. Hence, transmission by the third layer may be less than about 2%, such as less than about 2%, like essentially 0%.

Note that in general essentially no direct light from the light source will reach this layer in view of the presence of further layers (see below and above). Nevertheless, it is not excluded that there may be some light leakage directly under e.g. the solid state light source, e.g. a CSP LED, or at a gap between an anode and a cathode some light of the solid state light source may partially propagate through fourth layer element and may reach the third (protective) layer (even when upper layers would not be damaged). A percentage of the light source light that could reach the third layer (especially under the solid state light source), even when there is no damage of upper layers, may be about less than 5% of the total spectral power of the emitted light source light. However, would such further layers be damaged, than light from the light source may reach the third layer. The third layer may then protect the fourth layer element (and the fifth layer element) as a result of the absorption or reflection. Especially, the third layer is a reflective layer for the light (see also above).

The third layer may have a thickness selected from the range of 20 nm - 100 pm, such as 50 nm - 50 pm.

The fourth layer element may especially be configured in contact with at least part of the third layer element.

The fourth layer element may have a first side and a second side. In embodiments, at least part of the first side may in embodiments be directed to the fifth layer element. More especially, in embodiments at least part of the first side of the fourth layer element may be in contact with at least part of a second side (see also below) of the fifth layer element. Further, especially at least part of the second side of the fourth layer element may be in contact with at least part of the first side of the third layer element.

The fourth layer element may comprise a fourth layer. Especially, in embodiments the fourth layer is an electrically insulating layer. Especially, this may be the case when the third layer comprises an electrically conductive layer. Hence, in specific embodiments the third layer may be sandwiched between the second layer and the fourth layer. In yet further specific embodiments, the second layer and the fourth layer may fully enclose the third layer.

For instance, in embodiments a well-known dielectric layer may be provided (as fourth layer). In specific embodiments, the fourth layer may comprise an epoxy layer. In yet further specific embodiments, the fourth layer may comprise an epoxy layer hosting alumina particles and/or titania particles. In embodiments, this fourth (dielectric) layer may comprise a thin layer of one or more of silicon oxide (SiO_x) or silicon nitride. For instance, in embodiments silicon oxide or silicon nitride may be sputtered or deposited on top of third layer. Other solutions to reflect (or absorb light), like reflective flakes, etc., may also be possible.

In specific embodiments, a top layer of the third layer may be converted into the fourth layer. This may e.g. be the case when the third layer comprises a metal layer, and a top layer thereof is converted into an oxide of the metal, leading to a stack of the third layer being the metal layer and the fourth layer being a metal oxide layer of the metal layer. For instance, such oxide layer may be provided via an anodizing process. Hence, in embodiments the fourth layer may be configured in contact with the third layer, and the fourth layer may comprise anodized metal. However, other ways to provide the fourth layer may also be possible. For instance, methods may be selected from anodization, electro-chemical oxidation, thermal oxidation, or chemical treatment of the third layer surface.

The fourth layer may have a thickness selected from the range of 0.05-250 pm, such as 0.1-100 pm. In some embodiments, the fourth layer may have a thickness of at least 100 nm. In specific embodiments, the fourth layer may have a thickness of at maximum about 50 pm though smaller or larger thicknesses may also be possible.

The fifth layer element may especially be configured in contact with at least part of the fourth layer element.

The fifth layer element may have a first side and a second side. In embodiments, at least part of the first side may in embodiments be directed to an optional sixth layer element (see also below). More especially, in embodiments at least part of the first side of the fifth layer element may be in embodiments be in contact with at least part of a second side (see also below) of a sixth layer element. Further, especially at least part of the second side of the fifth layer element may be in contact with at least part of the first side of the fourth layer element.

Especially, the fifth layer element may comprise a fifth layer, wherein the fifth layer (551) is electrically conductive. For instance, the fifth layer may comprise a copper layer, such as a copper track. Hence, in general the fifth layer will only partly be available on a support layer (such as the fourth layer element or optionally the second layer element). Hence, the fifth layer element may in embodiments be only available on part of the fourth layer element. Optionally, part of the fifth layer element may in embodiments be available on part of the second layer element. This may be in at parts of the printed circuit board more remote from the light source or from a part configured to support a light source.

Therefore, especially the fifth layer may especially be configured without (electrically conductive) contact with the first layer. Should the third layer be electrically conductive, the fifth layer may especially also be configured without (electrically conductive) contact with third layer. Hence, in embodiments there are e.g. no vias between the third layer and the fifth layer.

The fifth layer may have a thickness selected from the range of 5-200 pm, such as 10-150 pm. In specific embodiments, fifth layer may have a thickness selected from the range of 15-100 pm, such as at least 20 pm.

Further layers or layer elements may be available, of which some will be discussed below.

In embodiments, the first layer element essentially consists of the first layer. In embodiments, the second layer element essentially consists of the second layer. In embodiments, the third layer element essentially consists of the third layer. In embodiments, the fourth layer element essentially consists of the fourth layer. In embodiments, the fifth layer element essentially consists of the fifth layer. In embodiments, the sixth layer element essentially consists of the sixth layer.

The invention provides in embodiments the printed circuit board as such, which can be used to host one or more light sources, especially at dedicated positions or parts, wherein (also) the third layer element is available. The invention also provides in embodiments the printed circuit board including the light source. In such embodiments, the system may also be indicated as “light generating system” or “lighting system”.

Hence, in embodiments the system further comprises the light source. Especially, the light source is functionally coupled to the printed circuit board. The light source may especially be configured to generate light (“light source light”), during operation of the light source.

Hence, especially in embodiments the light source is functionally coupled to the printed circuit board, and the light source is configured to generate light (during operation of the light source). More especially, the light source may comprise a solid state light source, such as a CSP LED. Further, in embodiments the light may comprise blue light. Alternatively or additionally, in embodiments the light may comprise UV radiation. In specific embodiments, the light may comprise a wavelength selected from the range of 190-430 nm.

The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The term “light source” may also refer to an organic light-emitting diode, such as a passive-matrix (P MOLED) or an active-matrix (AMOLED). In a specific embodiment, the light source comprises a solid state light source (such as a LED or laser diode). In an embodiment, the light source comprises a LED (light emitting diode). The term LED may also refer to a plurality of LEDs. Further, the term “light source” may in embodiments also refer to a so-called chips-on-board (COB) light source. The term “COB” especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB. Hence, a plurality of semiconductor light sources may be configured on the same substrate. In embodiments, a COB is a multi LED chip configured together as a single lighting module. The term “light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2-2000 solid state light sources.

The term “light source” may also refer to a chip scaled package (CSP). A CSP may comprise a single solid state die with (in embodiments) provided thereon a luminescent material comprising layer. The term “light source” may also refer to a midpower package. A midpower package may comprise one or more solid state die(s). The die(s) may be covered by a luminescent material comprising layer. The die dimensions may be equal to or smaller than 2 mm, such as in the range of e.g. 0.2-2 mm. Hence, in embodiments the light source comprises a solid state light source. Further, in specific embodiments, the light source comprises a chip scale packaged LED. Herein, the term “light source” may also especially refer to a small solid state light source, such as having a mini size or micro size. For instance, the light sources may comprise one or more of mini LEDs and micro LEDs. Especially, in embodiment the light sources comprise micro LEDs or “microLEDs” or “pLEDs”. Herein, the term mini size or mini LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm - 1 mm. Herein, the term p size or micro LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm and smaller. The light source may in embodiments comprise luminescent material. Hence, assuming a solid state light source, the solid state light source is configured to provide solid state light source light (during operation), which may at least partly be converted by the luminescent material into luminescent material light. Hence, the light source light of the light source may in embodiments comprise essentially only solid state light source light when the light source does not comprise a luminescent material, and may comprise luminescent material light and optionally solid state light source light when the light source comprises a luminescent material. The latter may depend upon a full-conversion configuration or partial conversion configuration. Hence, in embodiments the light source may comprise one or more of (a) a solid state light source and (ii) a solid state light source and a luminescent material (wherein the luminescent material is configured in a light-receiving relationship with the solid state light source). Note that the combination of solid state light source and luminescent material may in specific embodiments also be indicated as solid state light source.

The phrases “different light sources” or “a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of (solid state) light sources selected from at least two different bins. Likewise, the phrases “identical light sources” or “a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of (solid state) light sources selected from the same bin.

The light source may especially be of the type of light source of which part of the light source light propagates in a direction away of the support, but part of the light source light may in embodiments also reaches the support. For instance, a solid state light source may have a die from which part of the light source light also escapes from the edge. In another example, the light source may be a solid state light source with a luminescent material covered die, where luminescent material light from the luminescent material may also reach the support. Hence, in embodiments the light source and the support are configured such that part of the light source light during operation is directed to the support.

The part of the light source light directed to the support may be smaller than the part of the light source light that is not directed to the support. For instance, only a minor part may be directed to the support (and reach the layer element). In embodiments, the part of the light source light that is not directed to the support may be less than 20%, such as especially less than 10%, of the total power of the light source light that escapes from the light source. Hence, during operation the part of the light source light that irradiates the layered element may be less than 20%, such as especially less than 10%, of the total power of the light source light that escapes from the light source. A part of the solid state light source light, such as at maximum 5%, may escape from the solid state light source from below the solid state light source.

The light source (light) may have an optical axis essentially perpendicular to the support. Further, a substantial part, such as essentially all light source light, such as at least about 80%, such as especially at least 90% of the total power of the light source light that escapes from the light source may propagate in a direction away from the light source and support.

In the context of at least part of the light source light being directed to the support, it is noted that especially this may be due to the spatial light distribution of the light source, especially the solid state light source, and may not due the presence of (remote) optics. Of course, optics for e.g. beam shaping the light source light may be available, however, still part of the light source light may in embodiments be directed to the support. Another (substantial) part may be beam shaped with the (remote) optics (and will be directed away from the support).

Especially, the light source is functionally coupled to the PCB. Especially, the PCB may amongst others be a support for the light source (or other functional, especially electronic, component).

In embodiments, the light source may be configured to generate in an operational mode blue light. In embodiments, the light source may be configured to generate in an operational mode white light (comprising blue light). In embodiments, the light source maybe configured to generate in an operational mode UV light, especially having a wavelength selected from the range of 190-380 nm. In embodiments, the light source maybe configured to generate in an operational mode radiation having a wavelength selected from the range of 190-430 nm. In embodiments, the light source maybe configured to generate in an operational mode (infra)red radiation, such as in embodiments having a wavelength selected from the range of 780-2000 nm, like 780-1500 nm.

The term “white light” herein, is known to the person skilled in the art. It especially relates to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2700 K and 6500 K. In embodiments, for backlighting purposes the correlated color temperature (CCT) may especially be in the range of about 7000 K and 20000 K. Yet further, in embodiments the correlated color temperature (CCT) is especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL.

In an embodiment, the light source may also provide light source light having a correlated color temperature (CCT) between about 5000 and 20000 K, e.g. direct phosphor converted LEDs (blue light emitting diode with thin layer of phosphor for e.g. obtaining of 10000 K). Hence, in a specific embodiment the light source is configured to provide light source light with a correlated color temperature in the range of 5000-20000 K, even more especially in the range of 6000-20000 K, such as 8000-20000 K. An advantage of the relative high color temperature may be that there may be a relatively high blue component in the light source light.

The terms “visible” light or “visible emission” refer to radiation (herein especially indicated as “light”) having a wavelength in the range of about 380-750 nm.

Herein, UV (ultraviolet) may especially refer to a wavelength selected from the range of 190-380 nm, though in specific embodiments other wavelengths may also be possible.

Herein, IR (infrared) may especially refer to radiation having a wavelength selected from the range of 780-3000 nm, such as 780-2000 nm, e.g. a wavelength up to about 1500 nm, like a wavelength of at least 900 nm, though in specific embodiments other wavelengths may also be possible. Hence, the term IR may herein refer to one or more of near infrared (NIR (or IR-A)) and short-wavelength infrared (SWIR (or IR-B)), especially NIR.

The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light.

The terms “violet light” or “violet emission” especially relates to light having a wavelength in the range of about 380-440 nm. The terms “blue light” or “blue emission” especially relates to light having a wavelength in the range of about 440-495 nm (including some violet and cyan hues). The terms “green light” or “green emission” especially relate to light having a wavelength in the range of about 495-570 nm. The terms “yellow light” or “yellow emission” especially relate to light having a wavelength in the range of about 570- 590 nm. The terms “orange light” or “orange emission” especially relate to light having a wavelength in the range of about 590-620 nm. The terms “red light” or “red emission” especially relate to light having a wavelength in the range of about 620-780 nm. The term “pink light” or “pink emission” refers to light having a blue and a red component. The term “cyan” may refer to one or more wavelengths selected from the range of about 490-520 nm. The term “amber” may refer to one or more wavelengths selected from the range of about 585-605 nm, such as about 590-600 nm.

In general, the light source, or other functional component, may comprise at least two, such as two, electrical contacts.

Especially, the term “functional component” may refer to an electrical component. More especially, the functional component comprises one or more electrical components. The term electrical component may especially refer in embodiments to an electronic component.

The electronic component may include an active or a passive electronic component. An active electronic component may be any type of circuit component with the ability to electrically control electron flow (electricity controlling electricity). Examples thereof are diodes, especially light emitting diodes (LED). LEDs are herein also indicated with the more general term solid state lighting devices or solid state light sources. Hence, in embodiments the electronic component comprises an active electronic component. Especially, the electronic component comprises a solid state light source. Other examples of active electronic components may include power sources, such as a battery, a piezo-electric device, an integrated circuit (IC), and a transistor. In an embodiment, the electronic component comprises a driver. In yet other embodiments, the electronic component may include a passive electronic component. Components incapable of controlling current by means of another electrical signal are called passive devices. Resistors, capacitors, inductors, transformers, etc. can be considered passive devices. In an embodiment, the electronic component may include an RFID (Radio-frequency identification) chip. A RFID chip may be passive or active. Especially, the electronic component may include one or more of a solid state light source (such as a LED), a RFID chip, and an IC. The term “electronic component” may also refer to a plurality of alike or a plurality of different electronic components.

Here below, the invention is essentially further described in relation to a light source (as functional component, such as an electronic component). However, other functional components may also be available, and may be functionally coupled to the printed circuit board.

As indicated above, in general the light source, or other functional component, may comprise at least two, such as two, electrical contacts. Hence, the light source may be functionally coupled with two (or more) first parts. Especially, the light source may electrically conductively be coupled with two (or more) (different) fifth layers or with two (or more) (different) parts of fifth layers. These fifths layers or fifth layer parts may not be in direct electrical contact with each other, as this might lead to short-circuiting, but may be in embodiments only be in electrical conductive contact with each other via one or more of a source of electrical energy and an electrical component. In embodiments, (at least part ol) the fifth layers may be covered by the (LED) light source(s). In embodiments, the fifth layers may not cover the third layer (elements).

Hence, in specific embodiments, the light source may be functionally coupled to fifth layers of different first parts. In embodiments, the functional coupling may be achieved by soldering of the solid state light source, such as a CSP LED, or other electronic component, to the fifth layers, such as a Cu tracks. Other alternatives may include gluing with electrically conductive glues, anisotropic conductive adhesive or silver-sintering compression methods, or other possible methods known in the art. Another type of electromechanical connection may comprise welding by copper nano wires.

Two (or more) first parts may share all layer elements comprised by the respective first parts, except for the fact that the fifth layer elements of at least two of the respective first parts may not be in physical contact with each other. More especially, two (or more) first parts may share all layer elements comprised by the respective first parts, except for the fact that the fifth layer of at least two of the respective first parts may not be in direct electrically conductive contact with each other, and may in embodiments only be in embodiments in electrical conductive contact with each other via one or more of a source of electrical energy and an electrical component (such as a light source).

Further embodiments of the system are described below.

As indicated above, not only one of more first parts may be comprised by the printed circuit board, also one or more other parts may be available. A number of those other parts are non-limitingly be described below (and/or some were also indicate above).

In embodiment, the system may comprise a second part. More especially, the system may comprise one or more second parts.

Especially, at least at a second part of the printed circuit board the stack of layers may comprise at least part of the first layer element, at least part of the second layer element, at least part of the third layer element, at least part of the fourth layer element, at least part of the fifth layer element, and at least part of a sixth layer element. Especially, in embodiments the sixth layer element may be configured in contact with at least part of the fifth layer element.

The sixth layer element may have a first side and a second side. In embodiments, at least part of the first side may in embodiments be directed to the external, though further layer elements are not excluded. Further, especially at least part of the second side of the sixth layer element may be in contact with at least part of the first side of the fourth layer element.

In specific embodiments, the sixth layer element may cover a substantial part of the fifth layer element, but leaves some parts of the fifth layer element uncovered for a functional connection of the functional component, especially the electrical component such as a light source, with the printed circuit board.

Especially, in embodiments the sixth layer element comprises a sixth layer. In embodiments, the sixth layer may especially be configured to reflect and/or absorb light having the first wavelength. Especially, in embodiments the sixth layer may especially be configured to reflect the light.

As indicated above, the term “absorb” or “reflect” may refer to a partial absorption or partial reflection, respectively.

Would light reach the sixth layer, at least 50%, such as at least 60%, like at least 70% of the light may be reflected or absorbed. Even more especially, at least 80% of the light may be reflected or absorbed, yet even more especially at least about 90%. Here, the percentages refer to (spectral) power (in Watt).

In specific embodiments, the sixth layer may comprise a solder resist layer. Especially, in embodiments the sixth layer may comprise a white solder resist layer. The solder resist layer may comprise alumina particles and/or titania particles. Other solutions to reflect (or absorb light), like reflective flakes, etc., may also be possible. Alternatively or additionally, e.g. a PTFE (polytetrafluoroethylene) layer may be applied or other type of reflective coatings.

The sixth layer may have a thickness selected from the range of 5-200 pm, such as 10-150 pm. In specific embodiments, fifth layer may have a thickness selected from the range of 15-100 pm, such as at least 20 pm.

In embodiment, the system may comprise a third part. More especially, the system may comprise one or more third parts.

Especially, at least at a third part of the printed circuit board the stack of layers may comprise at least part of the first layer element, at least part of the second layer element, at least part of the third layer element, and at least part of the fourth layer element, and may not comprise the fifth layer.

In specific embodiments, in a variant on the third part, a (fifth) part of the printed circuit board the stack of layers may comprise at least part of the first layer element, at least part of the second layer element, at least part of the third layer element, at least part of the fourth layer element, at least part of the sixth layer element, and may not comprise the fifth layer.

For instance, in embodiments such third part may be below at least part of the light source (see further also below).

In specific embodiments, the third part is configured between two first parts, wherein the fifth layers of each of the two first parts are configured without physical contact. Hence, the third part may be used to provide (at least) two electrically insulated fifth layers (of fifth layer parts). As indicated above, these (at least) two electrically insulated fifth layers (of fifth layer parts) may in embodiments only be in electrical contact via an electrical component or a source of electrical energy.

For instance, at edges of the PCB, though at other position this may also be possible, the PCB comprises a fourth part, wherein the fourth part comprises part of the first layer element and part of the second layer element (in contact with the part of the first layer element), and no further parts of layer elements on the part of the second layer element. However, a an electrically insulating layer (part) in contact with the second side of the part of the first layer element may in embodiments also be possible.

Yet further, in specific embodiments, for instance in embodiments at parts more remote from the light source, where there may be essentially no light source light be directed to the PCB, the PCB may comprise a sixth part comprising the part of the first layer element, part of the second layer element (in contact with the part of the first layer element), part of the fifth layer element (in contact with the part of the second layer element), and part of the sixth layer element (in contact with the part of the fifth layer element).

Further parts are herein not excluded.

Hence, at least some of the layer elements may be comprised by different parts, like especially the first layer element and the second layer element, of which parts may in embodiments be comprised by any of the herein described embodiments of the first, second, third, fourth, fifth, and sixth part of the PCB.

As indicated above, in specific embodiments, the light source may be functionally coupled to fifth layers (or fifth layer parts) of different first parts. Note that different light sources may be functionally coupled to the same first parts.

For instance, when two light sources are configured in series, an anode or cathode of a first light source may be functionally coupled to a fifth layer (or fifth layer part) of the same first part as a cathode or anode of a second light source, etc.

Alternatively or additionally, for instance, when two light sources are configured parallel, an anode or cathode of a first light source may be functionally coupled to a fifth layer (or fifth layer part) of the same first part as a anode or cathode of a second light source, etc.

As indicated above, the second part may especially comprise a sixth layer that can be used to reflect (or absorb) light from the light source. As also indicated above, part of the light source light may reach the printed circuit board. Hence, especially those parts comprise the first part or the second part. Both the first part and the second part comprise the protective third layer. In addition, the second part may comprise a (protective) sixth layer. Especially, the sixth layer is reflective, which may increase efficiency of the system (as light generating system).

Therefore, in specific embodiments a first parts may be configured adjacent to at least one second part. Or, in embodiments a second part may be configured adjacent to a first part. As indicated above, especially the system may comprise (at least) two first parts. Therefore, in specific embodiments at least one of the two first parts is configured adjacent to at least one second part.

As indicated above, the sixth layer may be configured to reflect (or absorb) light from the light source. Hence, in embodiments the sixth layer may be configured in a light receiving relationship with the light source. Therefore, for part of the light, the sixth layer may be configured downstream of the light source.

The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is “upstream”, and a third position within the beam of light further away from the light generating means is “downstream”. In embodiments, the term “light-receiving relationship” and “downstream” may essentially be synonyms.

Especially, the sixth layer may extend below part of the light source. Hence, in specific embodiments, at least part of the sixth layer, more especially part of the sixth layer may be configured between the light source and the fifth layer element or optionally between the light source and the fourth layer element.

Alternatively or additionally, (also) for the third layer may apply that the third layer may be configured below at least part of the light source. However, especially at least part of the third layer may also be further away from the light source, like a kind of island at least partly surrounding the light source.

In specific embodiments, for the third layer may (therefore) apply one or more of: (a) at least part of the third layer may be configured between the first layer and the light source, and (b) at least part of the third layer may extend beyond a projection of the light source on the second layer.

In specific embodiments, at least part of the third layer may extend beyond the projection of the light source on the second layer with at least 2 mm, such as at least 3 mm. For instance, in specific embodiments, at least part of the third layer extends beyond the projection of the light source on the second layer with up to about 10 mm, though a larger (extension) is not excluded. In specific embodiments, essentially over the entire printed circuit board the third layer may be available. In other embodiments, the projection of the light source on the second layer may have a first area, and the third layer at the position of the light source may have a second area at least 20%, such as at least 50%, like at least 100% (i.e. twice as larger) larger than the first area.

As will be clear from the above, the PCB may also comprise a plurality of third layer elements, like patches of third layer elements, which may be aligned with the light source(s). Between parts with (parts ol) the third layer element, e.g. fourth parts or sixths parts may be available.

As indicated above, in specific embodiments the light source may comprise a chip scale package (CSP). Hence, in specific embodiments a plurality of chip scale package (CSP) may be functionally coupled to the PCB. For each chip scale package (CSP) may apply that the third layer may be configured below the chip scale package (CSP), but may also extend beyond a projection of the chip scale package (CSP) on the second layer (element).

Hence, in specific embodiments, a plurality of light sources, especially chip scale packages, may be functionally coupled to the printed circuit board, where for each of the light sources, especially chip scale packages, may apply that the light source is functionally coupled to fifth layers of different first parts. However, as indicated above, two or more light sources may be coupled to the same first part(s). In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. etc... The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein.

Hence, in an aspect the invention also provides a light generating device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, and an optical wireless communication device, comprising the light generating system as defined herein.

The light generating system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, green house lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating system (or luminaire) may be part of or may be applied in e.g. optical communication systems or disinfection systems.

The system may further comprise a control system (or be functionally coupled to a control system), configured to control the electronic component, such as especially the light source (s). Hence, in embodiments, the control system may control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and/or a predetermined time scheme.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: Figs, la-lb schematically depict some aspects;

Figs. 2a-2c schematically depict some embodiments and variants;

Fig. 3 schematically depicts some further aspects; and Fig. 4 schematically depicts some embodiments.

The schematic drawings are not necessarily to scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

At present, CSP LEDs are applied more in more in modules as they may offer a cost-effective alternative for high power LEDs. These CSP LEDs are applied on e.g. CEM1, CEM3 and IMS substrates. The use of the IMS substrates may be motivated by the thermal requirements; IMS may have the best thermal conductivity of the substrates mentioned. However, the application of CSP LEDs may also have a disadvantage. By the design of the CSP LED, strong (blue) light may escape at the bottom and at the sides of the CSP LED (see e.g. Fig. la). This (blue) light can have such a high intensity that it may damage epoxy -containing solder mask and/or the dielectric layers of the PCB substrate. For IMS substrates this might result in electrical safety issues. Instead of, or in addition, to blue light, also UV light (or UV radiation) may be applied.

Fig. la schematically depict an embodiment of a system 1000 comprising a printed circuit board 500 and a light source 100, especially a solid state light source, functionally coupled to the printed circuit board 500, wherein the light source 100 is configured to generate light 101.

The printed circuit board 500 comprises a stack of layers 509, wherein at least at a first part 501 of the printed circuit board 500 the stack of layers 509 comprises at least part of a first layer element 510, at least part of a second layer element 520, at least part of a fifth layer element 550, and at least part of a sixth layer element 560.

The first layer element 510 comprises a first layer 511, wherein the first layer 511 comprises a metal layer. The second layer element 520 is configured in contact with at least part of the first layer element 510, wherein the second layer element 520 comprises a second layer 521. The second layer 521 is an electrically insulating layer 521.

The fifth layer element 550 is configured in contact with at least part of the second layer element 520, wherein the fifth layer element 550 comprises a fifth layer 551, wherein the fifth layer 551 is electrically conductive. The fifth layer 551 is configured without (electrically conductive) contact with the first layer 511. The sixth layer element (560) is configured in contact with at least part of the fifth layer element (550). The sixth layer element (560) comprises a sixth layer (561). The sixth layer (561) is configured to reflect and/or absorb light (101) having the first wavelength.

Reference 200 refers to a luminescent material. References 105 refers to a light transmissive element, such as in embodiments a transparent silicone layer. Such light transmissive element, especially transparent silicone layer may be used to glue a reflective frame. Reference 109 refers to a reflective frame with angled wall. This reflective frame may be used to increase the amount of solid state light source light that escapes in a direction away from the die 106 (here the top layer) / from the light source 100 and the PCB 500. The reflective frame may comprise white silicone reflective material, such as silicone with reflective material embedded therein (like titania), though other solutions may also be possible. Reference 106 refers to a die of the solid state light source. Reference 108 refers to a solder connection and reference 107 refers to contact of the (solid state) light source.

In this embodiment, the luminescent material 200 is configured on the die 106 (and on part of the light transmissive element 105). The light source light 101 may escape in different directions. The spectral power composition may differ in different directions. For instance, in the upwards direction (away from the light source and the PCB), the light source light 101 may comprise at least luminescent material light and optionally solid state light source light. However, in the downward directions, the light source light 101 may substantially comprise solid state light source light and optionally luminescent material light.

Note that the invention is not only directed to light sources comprising solid state light sources including luminescent material, but also to solid state light sources without luminescent material.

As schematically depicted, it is not excluded that there may be some light leakage directly under e.g. the solid state light source, e.g. a CSP LED, or at a gap between an anode and a cathode some light of the solid state light source may partially propagate through 4th layer element and may reaching the third (protective) layer (even when upper layers would not be damaged).

In the proposed invention in embodiments it is amongst others proposed to apply an IMS substrate with a light-blocking layer (e.g. a thin metal layer), with specific configuration matching location of CSP LED on top surface like given below in Fig. 2a (see further below) (though Fig. 2a is not exclusively directed to CSP LEDs). Existing multi-layer PCB solutions do require expensive vias to enable electrical connection to a second metal conduction layer for interconnection and routing function, while proposed multi-layer structure with light-blocking layer does not require vias, so it can be made at lower costs, than when for light-blocking function will be used existing multi-layer PCBs with vias.

Fig. lb schematically depicts in embodiment I a dual layer technology for multi-layer electrical inter-connection for IMS PCBs (see also Fig. la) and with embodiment II an embodiment as defined herein (and claimed).

For instance, the middle layer may comprise an Al layer or Cu layer. The top layer may be a Cu layer.

With this middle Cu-layer a light-protection function may be supplied to underlying insulating layer. In case the top dielectric under top Cu layer gets damaged due to e.g. blue light, cracks can occur in only in top dielectric layer, but no safety issue may occur as the middle Cu layer may protect the dielectric that acts as an isolation layer between top electrically-active Cu layer and the metal-base layer.

With embodiment II in Fig. lb, an embodiment is schematically depicted of a system 1000 further comprising a third layer element 530 and a fourth layer element 540.

The third layer element 530 is configured in contact with at least part of the second layer element 520. The third layer element 530 is configured without contact with the first layer 511. The third layer element 530 comprises a third layer 531. The third layer 531 is configured to reflect and/or absorb light 101 having a first wavelength.

The fourth layer element 540 is configured in contact with at least part of the third layer element 530. The fourth layer element 540 comprises a fourth layer 541. The fourth layer 541 is an electrically insulating layer 521.

Amongst others, this invention may e.g. provide (more) optimal design details and a specification for upper dielectric layer and the light blocking layer, which may allow to realize require light protection function without significantly affecting a thermal resistance of such multilayer IMS PCB.

Fig. 2a-2b schematically depict cross-sectional views of embodiments of the system 1000.

Fig. 2a schematically depicts an embodiment of the system 1000. The system comprises a printed circuit board 500 and a light source 100, functionally coupled to the printed circuit board 500. The light source 100 is configured to generate light 101. The printed circuit board 500 comprises a stack of layers 509. At least at a first part 501 of the printed circuit board 500 the stack of layers 509 comprises at least part of a first layer element 510, at least part of a second layer element 520, at least part of a third layer element 530, at least part of a fourth layer element 540, and at least part of a fifth layer element 550 (see also Fig. 2c).

The first layer element 510 comprises a first layer 511. The first layer 511 comprises a metal layer. The second layer element 520 is configured in contact with at least part of the first layer element 510. The second layer element 520 comprises a second layer 521. The second layer 521 is an electrically insulating layer 521. Part of the second layer (element) is be configured in contact with part of the fourth layer (element).

The fourth layer element 540 is configured in contact with at least part of the third layer element 530. The fourth layer element 540 comprises a fourth layer 541, wherein the fourth layer 541 is an electrically insulating layer 521.

The fifth layer element 550 is configured in contact with at least part of the fourth layer element 540. The fifth layer element 550 comprises a fifth layer 551. The fifth layer 551 is electrically conductive. The fifth layer 551 is configured without (electrically conductive) contact with the first layer 511.

As shown, at least at a second part 502 of the printed circuit board 500 the stack of layers 509 comprises at least part of the first layer element 510, at least part of the second layer element 520, at least part of the third layer element 530, at least part of the fourth layer element 540, at least part of the fifth layer element 550, and at least part of a sixth layer element 560. The sixth layer element 560 is configured in contact with at least part of the fifth layer element 550. The sixth layer element 560 comprises a sixth layer 561. The sixth layer 561 is configured to reflect and/or absorb light 101 having the first wavelength.

In embodiments, the third layer 531 comprises a metal layer. The third layer 531 is configured without (electrically conductive) contact with the first layer 511 and the fifth layer 551.

In embodiment, the fourth layer 541 is configured in contact with the third layer 531. In specific embodiments, the fourth layer comprises anodized metal. In embodiments, at least at a third part 503 of the printed circuit board 500 the stack of layers 509 comprises at least part of the first layer element 510, at least part of the second layer element 520, at least part of the third layer element 530, and at least part of the fourth layer element 540, and does not comprise the fifth layer 551 (see also Fig. 2b and Fig. 2 for embodiments or variants).

As schematically depicted, the third part 503 is configured between two first parts 501, wherein the fifth layers 551 of each of the two first parts 501 are configured without physical contact.

At least one of the two first parts 501 is configured adjacent to at least one second part 502.

Especially, the light source 100 comprises a solid state light source, and wherein the light source 100 is functionally coupled to the printed circuit board 500, wherein light source 100 is configured to generate light 101. In embodiments, the light source may comprise a LED. In embodiments, the light source may comprise a CSP LED.

Especially, the light source 100 is functionally coupled to fifth layers 551 of different first parts 501.

As also indicated in Fig. la, the sixth layer 561 may be configured in a light receiving relationship with the light source 100.

In embodiments, the sixth layer 561 comprises a white solder resist layer.

In embodiments, for the third layer 531 applies one or more of: (a) at least part of the third layer 531 is configured between the first layer 511 and the light source 100, and (b) at least part of the third layer 531 extends beyond a projection of the light source 100 on the second layer 521.

The projection is indicated with DI, which may indicate e.g. the length and the width of the solid state light source. Note that DI only represent one of the dimensions of the projection, which may be rectangular or square. The solid state light source might also have a circular or oval projection.

In embodiments, the area beneath DI may comprise the third layer. This is especially important in case light is emitted to this part of the PCB. In embodiments, the fifth layer (elements) may be arranged beneath DI. This is the case e.g. if flip chip / CSP LED technology is being used.

As schematically depicted, at least part of the third layer 531 extends beyond the projection of the light source 100 on the second layer 521 with at least 2 mm, such as especially at least 3 mm. This extension is indicated with d. Fig. 2b schematically depicts another cross-section of (part ol) the PCB 500 with light source 100. Fig. 2b may a cross-sectional view of the same embodiment as schematically depicted in Fig. 2a (but another cross-section).

Figs. 2a-2b show some aspects of a proposed light-blocking layer structure and location in respect to CSP LED (or other light source) above it.

Referring to e.g. Figs. 2a and 2b, in general the fifth layer 551 may only partly be available on the fourth layer element or optionally partly on the second layer element, as the first layer may refer to electrically conductive tracks, such as copper tracks.

Fig. 2c schematically depict a number of parts. In fact, these may be crosssections over the entire height of the PCB 500, but over part of the length or width of the PCB 500.

Embodiment I shows a first part 501 as described above. Embodiment II shows a third part 503 as described above. Embodiments III shows a second part 502 as described above. Embodiment IV shows a fourth part 504 essentially comprising part of the first layer element and part of the second layer element (and not further parts of layer elements). Embodiment V shows a fifth part 505, essentially the same as the first part, but including part of the sixth layer element. Embodiment VI shows a sixth part 506 comprising part of the first layer element 510 and part of the second layer element 520, part of the fifth layer element 550, and part of the sixth layer element 560 (and not part of the third layer element 530 and not part the fourth layer element 540).

Hence, in embodiments the PCB 500 may comprise one or more first parts and one or more sixth parts. In other embodiments, embodiments the PCB 500 may comprise one or more first parts and one or more second parts. Other parts may be available as well, as schematically depicted in e.g. Figs, la, and 2a-2b.

Below, some aspects of the embodiments of the proposed invention for optimized PCB design are described.

In relation to the location of light-blocking layer it is noted that an aspect of light-blocking layer design is in embodiments to place this layer only at location, where it is essential to block high density of blue light emission originated from e.g. a CSP LED. It means it may in embodiments be located directly under CSP LED and its edges may in embodiments extend beyond edges of CSP LED (see also Figs. 2a-2b) in direction not covered by top Cu electrode layer (e.g. at gap between anode and cathode pads) at least in embodiments more than 3 mm for rim-type CSP LED, and more than 6 mm for cube-type CSP LED. Edges of light-blocking layer located under top Cu electrodes can have same width as dimension of the CSP LED above it, or may at least extend by 0.5 mm beyond edge of gap between anode and cathode soldering pad.

In relation to a thickness and electrical properties of upper dielectric layer it is noted that it may be useful to optimize thermal conductivity performance of such multi-layer IMS PCB. A function of this dielectric layer may be to provide basic electrical isolation between anode and cathode. This may require in embodiments one or more of: (a) this layer may be electrically non-conductive (to prevent electrical leakage channel between anode and cathode); (b) this dielectric layer can have relatively low breakdown voltage (e.g. >50 V); (c) this dielectric layer may have low thermal resistance.

For instance, this may imply that: (i) this 1st upper dielectric layer can be relatively thin (it can be significantly thinner that main isolating 2nd dielectric layer, if they both are made out of same type of material), (ii) alternatively, this dielectric layer can be made by oxidizing (e.g. anodizing) of upper surface of light-blocking (metal layer, e.g. if this layer is made out of Al foil); (iii) or this layer can be made using thin-film dielectric deposition processes (e.g. PECVD or sputtering) on surface of surface of light-blocking (metal) layer; (iv) or the light-blocking layer can be made out of high electrically -resistive (or non-conductive), yet high blue light absorbing (or reflecting) and light-stable material (e.g. carbon or graphene sheet, etc.).

In relation to the thickness and electrical properties of light-blocking (metal) layer may be indicated that property of light-blocking layer may in embodiments especially to absorb or reflect at least part of the (blue) light from LED that is received by the layer, and to prevent light propagation into underlying main isolation dielectric layer. Further, this lightblocking layer may in embodiments not introduce significant thermal resistance to the total thermal stack. Yet further, this layer can in embodiments be electrically non-conductive yet high blue light absorbing (or reflecting) and light-stable material. Further, in embodiments this layer can be made out of very thin metal sheet or film (its thickness can be as thin as 0.1 um), or at least thin enough to have essentially 0% of blue light (<480nm) transmission. This layer might have low electrical sheet conductivity.

In embodiments, in case of High-power CSP LED, it might be beneficial (yet not required) that this light-blocking layer can help additionally for lateral heat spreading from CSP LED above it and reducing total thermal resistance of PCB stack. For that purpose lateral thermal conductivity of this light blocking layer may in embodiments be about equal or higher than that for 1st Cu electrode layer. For purpose of effective heat spreading, this 2nd (metallic) light-blocking layer can extend beyond all edges of the CSP LED, especially by (at least) about 5 mm to each direction (see indication d in Figs. 2a-2b).

In embodiments, an additional following feature can be introduced into functionality of 1st upper dielectric layer and light-blocking (metal) film: restoration of electrical connection in case CSP LED failed as open-circuit mode (e.g. in case solder-joints crack will occur during operation of CSP LED module). Once CSP LED will failed as open circuit, then all voltage from LED driver for a module will be applied between anode and cathode at location of such failed CSP LED. This voltage might in embodiments be as high as 50-480 V, depending on type of LED driver in use (related to open circuit voltage of LED driver connected to CSP LED module). Such high voltage can be used to introduce electrical break-down between upper electrical metal layer and (metallic) light blocking layer under it. If energy of this electrical breakdown event is high enough, it might create high-energy air spark, or high-current conducting channel and such local channel might cause welding or interdiffusion of metals from upper Cu electrical layer and light blocking layer, and in turn creating persistent low-ohmic electrically-conductive channel between anode and cathode electrodes. In this case electrical conductivity over CSP LED module will be restored and whole CSP LED module will become operational again (except missing failed CSP LED). To ensure possibility of such restoration of electrical conductivity (by-pass creation in case of open-circuit failure mode) there might be additional criteria to properties, material choice and thicknesses of 1st dielectric layer and light-blocking (metal) film.

Fig. 3 schematically depicts how the current path can be restored with cracked solder-joint (upper embodiment) or even loss of the light source 100 (lower embodiment), such as a CSP LED. The black line shows how the current may flow.

In embodiments, in relation to the thickness and electrical properties of main lower insulating layer it is noted that a function of this bottom dielectric layer may be to ensure required level of electrical safety by providing sufficient electrical breakdown strength between upper metal layers (1st Cu electrodes and 2nd light-blocking layer). This layer may have a thickness for required level of electrical strength, such as in the order of about 100 pm, while it may also have required high level of thermal conductivity, such as at least about 1 W/(m*K). These requirements are same as for typical IMS dielectric, so standard IMS dielectric material with typical thickness can be used as bottom main insulation layer.

Fig. 4 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the light generating system 1000. Fig. 5 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000.

The term “plurality” refers to two or more.

The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%.

The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’.

The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

34

CLAIMS:

1. A system (1000) comprising a printed circuit board (500) and a light source

(100), functionally coupled to the printed circuit board (500), wherein the light source (100) is configured to generate light (101), wherein the printed circuit board (500) comprises a stack of layers (509), wherein at least at a first part (501) of the printed circuit board (500) the stack of layers (509) comprises at least part of a first layer element (510), at least part of a second layer element (520), at least part of a third layer element (530), at least part of a fourth layer element (540), and at least part of a fifth layer element (550), wherein: the first layer element (510) comprises a first layer (511), wherein the first layer (511) comprises a metal layer; the second layer element (520) is configured in contact with at least part of the first layer element (510), wherein the second layer element (520) comprises a second layer (521), wherein the second layer (521) is an electrically insulating layer (521); the third layer element (530) is configured in contact with at least part of the second layer element (520), wherein the third layer element (530) is configured without contact with the first layer (511), wherein the third layer element (530) comprises a third layer (531), wherein the third layer (531) is configured to reflect and/or absorb light (101) having a first wavelength; the fourth layer element (540) is configured in contact with at least part of the third layer element (530), wherein the fourth layer element (540) comprises a fourth layer (541), wherein the fourth layer (541) is an electrically insulating layer (521); the fifth layer element (550) is configured in contact with at least part of the fourth layer element (540), wherein the fifth layer element (550) comprises a fifth layer (551), wherein the fifth layer (551) is electrically conductive, wherein the fifth layer (551) is configured without contact with the first layer (511); wherein the light source (100) comprises one or more of (i) a solid state light source and (ii) a solid state light source and a luminescent material (200); and wherein the light source (100) is functionally coupled to the printed circuit board (500), wherein light source (100) is configured to generate light (101); 35 wherein the light source (100) is functionally coupled to fifth layers (551) of different first parts (501).

2. The system (1000) according to claim 1, wherein at least at a second part (502) of the printed circuit board (500) the stack of layers (509) comprises at least part of the first layer element (510), at least part of the second layer element (520), at least part of the third layer element (530), at least part of the fourth layer element (540), at least part of the fifth layer element (550), and at least part of a sixth layer element (560), wherein the sixth layer element (560) is configured in contact with at least part of the fifth layer element (550), wherein the sixth layer element (560) comprises a sixth layer (561), wherein the sixth layer (561) is configured to reflect and/or absorb light (101) having the first wavelength.

3. The system (1000) according to any one of the preceding claims, wherein the third layer (531) comprises a metal layer, and wherein the third layer (531) is configured without contact with the first layer (511) and the fifth layer (551).

4. The system (1000) according to any one of the preceding claims, wherein the third layer element may have a first side and a second side, the first side of the third layer element is in contact with part of a second side of the fourth layer element, and the second side of the third layer element is in contact with part of the first side of the second layer element.

5. The system (1000) according to any one of the preceding claims, wherein at least at a third part (503) of the printed circuit board (500) the stack of layers (509) comprises at least part of the first layer element (510), at least part of the second layer element (520), at least part of the third layer element (530), and at least part of the fourth layer element (540), and does not comprise the fifth layer (551).

6. The system (1000) according to claims 2 and 5, wherein the third part (503) is configured between two first parts (501), wherein the fifth layers (551) of each of the two first parts (501) are configured without physical contact.

7. The system (1000) according to claim 6, wherein at least one of the two first parts (501) is configured adjacent to at least one second part (502).

8. The system (1000) according to any one of the preceding claims, wherein the system comprises more light sources and the PCB comprises a plurality of third layer elements which are aligned with the light sources.

9. The system (1000) according to any one of the preceding claims, wherein part of the second layer element is configured in contact with part of the fourth layer element.

10. The system (1000) according to any one of the preceding claims and according to claim 2, wherein the sixth layer (561) is configured in a light receiving relationship with the light source (100).

11. The system (1000) according to claim 10, wherein the sixth layer (561) comprises a white solder resist layer.

12. The system (1000) according to any one of the preceding claims, wherein for the third layer (531) applies one or more of: (a) at least part of the third layer (531) is configured between the first layer (511) and the light source (100), and (b) at least part of the third layer (531) extends beyond a projection of the light source (100) on the second layer (521).

13. The system (1000) according to claim 12, wherein at least part of the third layer (531) extends beyond the projection of the light source (100) on the second layer (521) with at least 2 mm.

14. The system (1000) according to any one of the preceding claims, wherein the light source (100) comprises a chip scale package (CSP).

15. A light generating device (1200) selected from the group of a lamp (1), a luminaire (2), a projector device (3), a disinfection device, and an optical wireless communication device, comprising the light generating system (1000) according to any one of the preceding claims.