CN110873296B

CN110873296B - Solid state element lighting strip design

Info

Publication number: CN110873296B
Application number: CN201910614092.5A
Authority: CN
Inventors: M·J·范尤登; C·M·苏
Original assignee: Signify Holding BV
Current assignee: Signify Holding BV
Priority date: 2018-08-31
Filing date: 2019-07-09
Publication date: 2024-02-09
Anticipated expiration: 2039-07-09
Also published as: CN110873296A; CN210637860U; WO2020043727A1

Abstract

The invention discloses a solid state element lighting strip design. Wherein there is provided an elongated substrate having opposite ends in an elongation direction thereof, and comprising: a conductive line arrangement comprising conductive lines arranged to have a first polarity; a further electrically conductive wire arranged to have a polarity opposite to the first polarity and spatially separated from the electrically conductive wire, each of the electrically conductive wire and the further electrically conductive wire extending between opposite ends and terminating at a respective metal pad at each of the opposite ends; and at least one solid state lighting arrangement comprising a plurality of strings of N series-connected solid state elements, where N is a positive integer, the strings being connected in parallel to the electrically conductive wire and the further electrically conductive wire and separated from each other by the spacer section. An illumination strip assembled from such elongated substrates and a method of assembling such an illumination strip are also disclosed.

Description

Solid state element lighting strip design

Technical Field

The present invention relates to an elongated substrate having opposite ends in an elongation direction thereof, and comprising: a conductive line arrangement comprising conductive lines arranged to have a first polarity; a further electrically conductive wire arranged to have a polarity opposite to the first polarity and spatially separated from the electrically conductive wire, each of the electrically conductive wire and the further electrically conductive wire extending between opposite ends and terminating at a respective metal pad at each of the opposite ends; and at least one solid state lighting arrangement comprising a plurality of strings of N series-connected solid state elements, wherein N is a positive integer, the strings being connected in parallel to the electrically conductive wire and the further electrically conductive wire and being separated from each other by the spacer section.

The invention also relates to an illumination strip comprising a plurality of such elongated substrates interconnected to form the strip.

The invention also relates to the manufacture of such a lighting strip.

Background

Lighting applications based on Solid State Lighting (SSL) elements require more and more flexibility. Thus, the variation of linear elongated substrates, such as PCBs (printed circuit boards), with surface mounted SSL elements is rapidly increasing. Such an illumination strip may be provided on a reel so as to allow the illumination strip to be cut to a desired length, particularly in the case of flexible elongate substrates such as flexible PCBs. For example, US 2015/013872 A1 discloses an LED strip lighting fixture having an LED array mounted on a frangible rigid aluminum base having a predetermined thickness including predetermined weaknesses whereby the rigid (preferably aluminum) base may be broken at the predetermined weaknesses. The rigid base has a stacked integrated circuit disposed thereon on which are mounted a plurality of electrical components including a plurality of light emitting diodes electrically connected in series on the stacked integrated circuit, whereby the frangible sections of the rigid base provide predetermined length dimensions that are easily customizable to provide the rigid aluminum base and the LED-mounted lighting fixture.

However, the manufacture of such illumination strips is not without challenges. Such strips may be produced using a roll-to-roll production method, but this typically requires specialized equipment to manufacture the (flexible) elongated substrate and to perform a Surface Mount Device (SMD) process in which the chip comprising SSL elements is mounted onto the elongated substrate. This is quite expensive, which is why many manufacturers use a strip-to-strip welding method to produce such illumination strips, wherein elongated substrates are welded together to form the illumination strips, after which the illumination strips are overmolded to protect and electrically insulate the electronic components exposed on the surface of the illumination strips to form the final product. In this way, for example, lighting strips of a length of 5-50m or more may be provided, while such lighting strips may still be manufactured using standard tools, since the SMD process of mounting SSL element chips onto an elongated substrate, such as a (flexible) PCB, is performed using a relatively short substrate, for example a substrate of about 50cm long, which may still be handled by such standard tools.

To facilitate cutting of these strips to length, the strips typically comprise strings of SSL elements (e.g., LEDS) connected in parallel, such that the illumination strips may be cut with the space between adjacent pairs of such parallel strings. To this end, the illumination strip may include indicia at such a space that indicates where the illumination strip may be safely cut (e.g., using scissors). However, in such designs, the spaces between adjacent parallel strings on adjacent elongated substrates (i.e., the joints between such adjacent elongated substrates) cannot be easily cut due to the welding of the conductive lines extending across the elongated substrates.

In addition, in order to reconnect the cut strip sections, a connector box is generally used into which the cut strip sections are inserted. In the case of cutting such strip sections on such solder bumps, the thickness of the solder bump sections typically prevents such cut strip sections from being inserted into the connector box. For this reason, users of such soldered lighting strips tend to avoid cutting the strip on soldered interconnects interconnecting adjacent elongated substrates. However, this means that the lighting strip has spaces between the strings of regularly spaced SSL elements that are not easily cut, which thus hampers the flexibility of use of such lighting strips.

For example, for a woven lighting strip that is welded together from 50cm long substrates, a user desiring to cut the length of the lighting strip at 50cm or multiples thereof cannot simply cut the length of the lighting strip, as this means cutting across the welded interconnects between adjacent substrates. Instead, the user must first cut out a smaller portion, e.g. a portion of 5cm or 10cm, after which a portion of 50cm or a multiple thereof can be cut out from the remaining length of the lighting strip, since now the cross lighting strip cut at the length of the desired portion will be made at the spaces between strings of SSL elements positioned on the same substrate. This is quite cumbersome and results in unnecessary wastage of parts of the illumination strip.

Disclosure of Invention

The present invention aims to provide an elongated substrate (elongate substrate) for use in such lighting strips, wherein a user can cut the lighting strips equally easily between each pair of adjacent strings of SSL elements, thereby increasing the flexibility of use of such lighting strips and reducing waste thereof.

The present invention is also directed to an illumination strip formed from a plurality of such elongated substrates.

The invention also aims to provide a method of manufacturing such an illumination strip.

According to a first aspect, there is provided an elongate substrate having opposite ends in its elongate direction, and comprising: a conductive line arrangement comprising conductive lines arranged to have a first polarity; a further electrically conductive wire arranged to have a polarity opposite to the first polarity and spatially separated from the electrically conductive wire, each of the electrically conductive wire and the further electrically conductive wire extending between opposite ends and terminating at a respective metal pad at each of the opposite ends; and at least one solid state lighting arrangement comprising a plurality of strings of N series-connected solid state elements, wherein N is a positive integer, the strings being connected in parallel to the electrically conductive wire and the further electrically conductive wire and separated from each other by spacer sections; and at least one of the following: a string of M series-connected solid state elements, wherein M is a positive integer and M < N, said string being adjacent one of said opposite ends and being connected between said conductive line and a first further metal pad at said one of said opposite ends; and a string of N-M series-connected solid state elements, the string being proximate to the other of the opposite ends and connected between a further conductive line and a second further metal pad at the other of the opposite ends. When the elongated substrate is interconnected with another elongated substrate having N-M complementary strings of serially connected solid state elements and/or M complementary strings of serially connected solid state elements, one of the M strings of serially connected solid state elements and the N-M strings of serially connected solid state elements on the elongated substrate is connected with a corresponding one of the N-M complementary strings of serially connected solid state elements and the M complementary strings of serially connected solid state elements on the other elongated substrate to form N strings of serially connected solid state elements across adjacent elongated substrates; wherein the above-described strings of N series-connected solid state elements are electrically and optically identical to each of the plurality of strings of N series-connected solid state elements across adjacent elongated substrates.

According to the present invention, an elongated substrate is provided which, when used to form an illumination strip by interconnecting a plurality of such substrates, ensures that the illumination strip can be cut between each pair of adjacent strings of Solid State Lighting (SSL) elements, thereby reducing the wastage of such illumination strips and increasing its user flexibility. This is achieved by dividing such strings of serially connected SSL elements at their intersection points across adjacent elongate substrates such that a first portion of such strings (i.e. strings of M serially connected solid elements) is positioned on a first one of the adjacent elongate substrates, which first portion may be interconnected to a second portion of such strings (i.e. strings of N-M serially connected solid elements) on another one of the adjacent elongate substrates, thereby forming a string of m+ (N-M) =n serially connected SSL elements across the adjacent elongate substrates. Thus, the interconnects (e.g., solder bumps) between adjacent elongated substrates are no longer positioned between a pair of strings of serially connected SSL elements, but rather within strings that are positioned outside the potential target cut areas of the illumination strip formed by a plurality of such interconnected substrates. The strings of N series-connected solid state elements have the same electrical and optical properties across adjacent elongated substrates as the normal strings of N series-connected strings of solid state elements, such that the lighting strip formed by interconnecting such substrates does not have variations in its direction of elongation.

In case the elongated substrate comprises only one string of M series connected strings of solid state elements and N-M series connected strings of solid state elements, the elongated substrate may be used as a terminal substrate for such an illumination strip, since in this case the further elongated substrate does not need to be connected to the terminal end of the elongated substrate, such that a string portion at the terminal end is not needed. On the other hand, in case an elongated substrate is used as an intermediate substrate for such a lighting strip, the at least one solid state lighting arrangement comprises a string of M series connected solid state elements and a string of N-M series connected solid state elements, such that the elongated substrate may be interconnected at its opposite ends to another elongated substrate, so that a string of N series connected SSL elements as described above is formed across the interconnected elongated substrates.

In the context of the present application, when referring to a conductive wire arranged to have a specific polarity, it is to be understood that this means that the conductive wire is intended to be connected to a specific terminal of a power supply, such as a positive terminal or a negative terminal. For example, a conductive wire arranged to have a first polarity may be intended to be connected to a positive terminal of a power supply, in which case a conductive wire having an opposite polarity is intended to be connected to a negative terminal of such a power supply, and vice versa.

Preferably, each of the strings of N series-connected solid-state elements described above extends in the direction of elongation of the elongated substrate.

It is further preferred that the elongate substrate is flexible so as to maximize the flexibility of the illumination strip formed by a plurality of such interconnected elongate substrates.

Each solid state element may be provided as a separate chip mounted on an elongated substrate. This facilitates cost-effective manufacturing of such elongated substrates, for example using SMD processes.

Embodiments of the invention are not limited to a single SSL arrangement on an elongated substrate. For example, in another embodiment, the electrically conductive wire arrangement comprises a pair of electrically conductive wires arranged to have the above-mentioned first polarity, and a pair of the above-mentioned solid state lighting arrangements comprising a first solid state lighting arrangement and a second solid state lighting arrangement, wherein a respective string of the first solid state lighting arrangement is connected to one electrically conductive wire of the pair of electrically conductive wires arranged to have the above-mentioned first polarity if connected to the electrically conductive wire arranged to have the above-mentioned first polarity, and a respective string of the second solid state lighting arrangement is connected to the other electrically conductive wire of the pair of electrically conductive wires arranged to have the above-mentioned first polarity if connected to the electrically conductive wire arranged to have the above-mentioned first polarity. In such an embodiment, the elongated substrate comprises a plurality of SSL arrangements that are individually addressable, which may for example be used to provide the elongated substrate with different types of SSL elements, such as white SSL elements in a first SSL arrangement and SSL elements in a second SSL arrangement that produce a specific color (e.g. red, green or blue). This enhances the functionality of such an elongated substrate and an illumination strip formed by a plurality of such elongated substrates.

The elongated substrate generally includes a first major surface and a second major surface opposite the first major surface. In one embodiment, a pair of conductive wires and a pair of solid state lighting arrangements arranged with the first polarity described above are positioned on the first major surface and further conductive wires are positioned on the second major surface. This has the following advantages: more space is available on the first main surface, e.g. a main surface that serves as a light generating surface visible in the lighting strip, which may help to include further SSL arrangements on the first main surface.

For example, the conductive line arrangement may comprise a third conductive line arranged with the above-mentioned first polarity, the elongated substrate further comprising a further solid state lighting arrangement, wherein a respective string of further solid state lighting arrangements is connected to the third conductive line if connected to the conductive line arranged with the above-mentioned first polarity. The further SSL arrangement may further enhance the functionality of the elongated substrate and the illumination strip formed by a plurality of such substrates, for example by providing a plurality of SSL elements within such SSL arrangement that generate light having a further spectral composition. In this way, elongated substrates and lighting strips with up to four or five different SSL arrangements may be provided, such as elongated substrates and lighting strips comprising one or two SSL arrangements with (different) white light SSL elements, and three further SSL arrangements with SSL elements that respectively generate different colors of light (such as red, green and blue light).

In one embodiment, each of the conductive lines arranged to have the first polarity and the further conductive lines comprises a plurality of further metal pads, wherein each of the further metal pads is conductively connected to a junction between the conductive line and one end of the plurality of strings of N series-connected solid state elements connected to the conductive line. Such additional metal pads facilitate reconnecting the sections of the illumination strip cut near such junction, for example, when the illumination strip sections are to be used in or as an illumination device. Such further metal pads may be positioned in the above-mentioned spacer sections, so that the design of the elongated substrate is kept particularly compact.

According to another aspect, there is provided a lighting strip comprising a plurality of elongate substrates according to any of the embodiments described herein, wherein the respective substrates are interconnected by a pair of interconnects interconnecting corresponding conductive lines and metal pads of the further conductive lines at facing ends of adjacent elongate substrates, and a further interconnect interconnecting a first further metal pad of each solid state lighting arrangement on one of the adjacent elongate substrates to a second further metal pad of the corresponding solid state lighting arrangement on the other of the adjacent elongate substrates at said facing ends, wherein across the adjacent elongate substrates each string of the N series-connected solid state elements is the same as each string of the plurality of strings of N series-connected solid state elements in the length direction of the elongate substrates.

The interconnects (e.g. solder bumps) of such lighting strips are positioned within the SSL arrangement of the N series-connected SSL elements, as explained in more detail above, so that the lighting strips can be easily cut between each pair of adjacent or neighboring SSL arrangements. This is an improvement over the prior art in which such cutting cannot be easily performed between adjacent SSL arrangements at different substrates, as the solder bumps between such substrates are typically positioned between adjacent SSL arrangements, i.e. in the area to be cut, which virtually excludes such cutting between SSL arrangements at different substrates. By appropriately selecting the lengths of the strings of M series-connected solid state elements on one substrate and the lengths of the strings of N-M series-connected solid state elements on the other (adjacent and complementary) substrate, the lengths of the strings of N series-connected solid state elements across the adjacent elongated substrate may be the same as the normal strings of the plurality of strings of N series-connected solid state elements, such that the lighting strip formed by interconnecting such substrates has even better uniformity along its elongated direction.

It should be noted that such lighting strips may be formed of elongated substrates, each comprising a string portion of M series-connected solid state elements (where M is a positive integer) and a string portion of N-M series-connected solid state elements, in which case the terminals of the lighting strips may be cut off from the portions of the elongated substrates to form terminals of the lighting string that may be connected to a power supply or the like. In order to save costs, the portion of the terminal elongated substrate of the illumination strip to be discarded may not carry SSL elements, e.g. no SSL elements are mounted in the SMD process. It will be appreciated that this approach is feasible when the end user is knowledgeable about what length of illumination strip is required. The advantage of this approach is that only a single type of elongated substrate needs to be produced for assembling such a lighting strip, i.e. an elongated substrate comprising a string portion of M series-connected solid state elements (where M is a positive integer) and a string portion of N-M series-connected solid state elements at opposite ends of the substrate.

However, without knowing how many lighting strips the end customer will use, it is preferable that the lighting strips further include a pair of terminal elongated substrates at opposite ends of the lighting strips, the pair of terminal elongated substrates comprising: a first terminal elongated substrate that does not include a string of M solid state elements connected in series, such that a terminal end of the first terminal elongated substrate includes only the above-described conductive lines and metal pads of the further conductive lines; and a second terminal elongated substrate that does not include a string of N-M series-connected solid state elements, such that a terminal end of the second terminal elongated substrate includes only the above-described conductive lines and metal pads of the further conductive lines.

According to a further aspect, there is provided a method of manufacturing a lighting strip according to any of the embodiments described herein, the method comprising interconnecting a plurality of elongated substrates according to any of the embodiments described herein, wherein the respective substrates are interconnected by a pair of interconnects interconnecting metal pads of the corresponding conductive wire and the further conductive wire at facing ends of adjacent elongated substrates, and further interconnects interconnecting a first further metal pad of each solid state lighting arrangement on one of the adjacent elongated substrates to a second further metal pad of the corresponding solid state lighting arrangement on the other of the adjacent elongated substrates at the above facing ends. This approach provides an illumination strip that can be easily cut between any pair of adjacent SSL arrangements, at the cost of additional interconnects between string portions of SSL arrangements distributed across a pair of adjacent elongated substrates.

The method may further include terminating opposite ends of the illumination strip with a pair of terminal elongated substrates comprising: a first terminal elongated substrate that does not include a string of M series-connected solid state elements, such that a terminal end of the first terminal elongated substrate includes only the conductive lines and the metal pads of the further conductive lines; and a second terminal elongated substrate that does not include a string of N-M solid state elements connected in series, such that a terminal end of the second terminal elongated substrate includes only the metal pads of the conductive wire and the additional conductive wire; interconnecting at opposite ends of said substrates respective metal pads of said conductive wires of the first terminal elongated substrate to respective metal pads of corresponding conductive wires of adjacent elongated substrates of the first terminal elongated substrate, and interconnecting at said facing ends one or more second further metal pads of the first terminal elongated substrate to corresponding first further metal pads of adjacent elongated substrates of the first terminal elongated substrate; and interconnecting respective metal pads of the conductive lines of the second terminal elongated substrate to corresponding metal pads of conductive lines of adjacent elongated substrates of the second terminal elongated substrate at the facing ends of the substrates, and interconnecting one or more first additional metal pads of the second terminal elongated substrate to corresponding second additional metal pads of adjacent elongated substrates of the second terminal elongated substrate at the facing ends. In this way, a lighting strip is manufactured which can be directly connected to a power supply or the like at its terminals.

In a preferred embodiment, the above-described interconnection comprises soldering in order to provide a particularly robust and reliable interconnection.

Drawings

Embodiments of the invention will be described in more detail by way of non-limiting examples with reference to the accompanying drawings, in which:

FIG. 1 is a circuit diagram of an elongated substrate of a first type according to one embodiment;

FIG. 2 is a circuit diagram of a second type of elongated substrate according to one embodiment;

FIG. 3 is a circuit diagram of a third type of elongated substrate according to one embodiment;

FIG. 4 schematically depicts a layout of a portion of an elongated substrate according to an example embodiment;

FIG. 5 is a circuit diagram of a portion of an assembled lighting strip according to one embodiment of the method of the present invention;

FIG. 6 is a circuit diagram of another portion of an assembled lighting strip according to one embodiment of the method of the present invention;

FIG. 7 schematically depicts a layout of a portion of a lighting strip according to an example embodiment;

FIG. 8 is a circuit diagram of an elongated substrate of a first type according to another embodiment;

FIG. 9 is a circuit diagram of a second type of elongated substrate according to another embodiment;

FIG. 10 is a circuit diagram of a third type of elongated substrate according to another embodiment;

FIG. 11 schematically depicts a layout of a portion of a lighting strip according to another example embodiment;

FIG. 12 is a circuit diagram of an elongated substrate of a first type according to yet another embodiment;

FIG. 13 is a circuit diagram of a second type of elongated substrate according to yet another embodiment;

FIG. 14 is a circuit diagram of a third type of elongated substrate according to yet another embodiment;

fig. 15 schematically depicts a layout of a portion of a lighting strip according to yet another example embodiment; and

fig. 16 schematically depicts a layout of a portion of another lighting strip (not part of the invention).

Detailed Description

It should be understood that the figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the drawings to indicate the same or similar parts.

Fig. 1 schematically depicts a circuit diagram of an elongated substrate 100 of a first type for assembly into an illumination strip according to one embodiment of the invention. The elongated substrate 100 may be made of any suitable material. For example, the elongated substrate 100 may be a Printed Circuit Board (PCB), and preferably the elongated substrate 100 is a flexible PCB. It should be noted that flexible PCBs are well known per se, and therefore, for brevity, it will not be explained how such flexible PCBs are provided. The elongated substrate 100 extends in its elongated direction between opposite ends 103 and 105. The further conductive line 120 arranged with a first polarity and the further conductive line 120 arranged with a polarity opposite to the first polarity each extend between opposite ends 103 and 105. For example, the conductive line 110 may be arranged with positive polarity, while the further conductive line 120 may be arranged with negative polarity, and vice versa.

The conductive lines 110 terminate at respective metal pads 111 and 112 at opposite ends 103 and 105 of the elongated substrate 100, the metal pads 111 and 112 may be used to interconnect the conductive lines 110 of the elongated substrate 100 to corresponding conductive lines on another elongated substrate or to a terminal of a particular polarity (e.g., a positive terminal), such as a power supply. The further conductive lines 120 terminate at respective metal pads 121 and 122 at opposite ends 103 and 105 of the elongated substrate 100, which metal pads 121 and 122 may be used to interconnect the further conductive lines 120 of the elongated substrate 100 to corresponding further conductive lines on the further elongated substrate or to a further terminal (e.g., negative terminal) of a particular polarity, such as a power supply. The conductive line 110 and the further conductive line 120 may be made of any suitable conductive material, such as copper, for example. Similarly, the respective metal pads 111, 112, 121, and 122 may be made of any suitable conductive material (such as copper), for example. The metal pads may also be coated with another conductive material (e.g., gold, etc.) to facilitate electrically interconnecting the metal pads (e.g., using solder) with another metal pad, a power source, etc.

The elongated substrate 100 also carries an SSL arrangement comprising a plurality of strings 130 of N series-connected SSL elements 101, the strings 130 being connected in parallel between the conductive wires 110 and the further conductive wires 120. In the context of the present application, N is a positive integer having a value of at least 2, and preferably having a value of at least 5. For example, N may be 5, 6, 7, 8, 9, 10 or more. In fig. 1, the SSL arrangement further comprises a first further string 140 of M series-connected SSL elements 101, where M is a positive integer, where M < N. The first further string 140 is connected between the conductive line 110 and the first further metal pad 141 at the first end 105 of the elongated substrate 100. The SSL arrangement further comprises a second further string 150 of N-M series-connected SSL elements 101 connected between the second further metal pads 151 and the further conductive wires 120 at the other end 103 of the elongated substrate 100. In this application, such an elongated substrate 100 will also be referred to as a B-type substrate. The SSL elements 101 within a single SSL arrangement are typically of the same type, i.e. typically produce a luminescence output that is substantially the same in terms of luminescence output intensity and spectral composition.

When a pair of B-type elongated substrates 100 are interconnected into a lighting string, the end portion 105 of a first B-type elongated substrate 100 will face the end portion 103 of an adjacent B-type elongated substrate 100. Such elongated substrates 100 are then interconnected by: the metal pads 112 of the conductive lines 110 on the first B-type elongated substrate 100 are interconnected (e.g., soldered) to the metal pads 111 of the corresponding conductive lines 110 of the adjacent B-type elongated substrate 100, and the metal pads 122 of the further conductive lines 120 on the first B-type elongated substrate 100 are interconnected (e.g., soldered) to the metal pads 121 of the corresponding further conductive lines 120 of the adjacent B-type elongated substrate 100. Furthermore, the first further metal pads 141 of the first further string 140 on the first B-type elongated substrate 100 are interconnected (e.g. soldered) to the second further metal pads 151 of the second further string 150 on the adjacent B-type elongated substrate 100, thereby forming a further string 130 of N series connected SSL elements 101, which further string 130 is distributed over the first B-type elongated substrate 100 and its adjacent B-type elongated substrate 100.

Thus, the elongated substrates 100 (e.g., when forming a portion of an illumination strip) may be cut as symbolically depicted by the dashed lines ending in pairs of scissors at the spacers or cut regions 115 between any adjacent strings 130, the spacers or cut regions 115 being held without interconnection between adjacent elongated substrates 100, since no strings 130 end in a position coinciding with the edges of the elongated substrates 100 due to the formation of strings 130 by interconnecting the first further strings 140 and the second further strings 150 across the respective boundaries of adjacent elongated substrates 100. Each string 130 of N series-connected SSL elements 101 may be further connected to a further metal pad 114 of a conductive wire 110 and a further metal pad 124 of a further conductive wire 120, such that such a further metal pad is conductively connected to the junction between its conductive wire and one end of such a string 130. The presence of such additional metal pads 114, 124 (which may be positioned in the spacer region 115 in some embodiments) facilitates reconnection of the cut portions of the elongated substrate 100, for example, when forming a string or a portion of a daisy chain of interconnected elongated substrates 100 (e.g., illumination strips, etc.).

The type B elongated substrate 100 may be used as an intermediate substrate for such a daisy-chained arrangement, for example, an illumination strip according to an embodiment of the present invention, which is why both string portions 140, 150 are present at the respective ends 105, 103 of the elongated substrate 100 in order to interconnect the type B elongated substrate 100 at both ends to another elongated substrate 100 according to an embodiment of the present invention. However, in case such an elongated substrate 100 is to be used as a daisy-chained terminal substrate for such interconnected elongated substrates 100 (e.g. lighting strips, etc.), only one of its ends 103, 105 is to be connected to the other elongated substrate 100, such that the other end does not need to contain the first or second further strings 140, 150 of the SSL arrangement.

Fig. 2 schematically depicts a circuit diagram of an elongated substrate 100 suitable for use as such a terminal substrate, wherein at its ends 105 only a first further string 140 of SSL arrangements is present. Such an elongated substrate 100 will also be referred to herein as an a-type substrate. Thus, the opposite end 103 of the a-type elongated substrate 100 does not comprise the second further string 150, but only comprises metal pads 111, 121 for interconnecting the conductive lines 110 and the further conductive lines 120, respectively, to, for example, a power supply or the like.

Fig. 3 schematically depicts a circuit diagram of an elongated substrate 100 suitable for use as such a terminal substrate, wherein at its ends 103 only a second further string 150 of SSL arrangements is present. Such an elongated substrate 100 will also be referred to herein as a C-type substrate. Thus, the opposite end 105 of the C-shaped elongated substrate 100 does not comprise the first further string 140, but only comprises metal pads 112, 122 for interconnecting the conductive lines 110 and the further conductive lines 120, respectively, to, for example, a power supply or the like.

It should be noted at this point that each of the a-, B-and C-type elongated substrates 100 may comprise any suitable number of strings 130 of N series-connected SSL elements 101. Different types of elongated substrates 100 may include different numbers of strings 130. Similarly, different instances of the same type of substrate 100 (e.g., different instances of type B elongated substrate 100) may include different numbers of strings 130, but for simplicity of manufacture, preferably different instances of the same type of elongated substrate 100 include the same number of strings 130.

Fig. 4 schematically depicts a layout of a portion of an elongated substrate 100 according to an example embodiment. In this layout, which depicts terminal sections of such a substrate 100 including its ends 105, it can be shown that strings 130 of N series-connected SSL elements 101 extend in the direction of elongation of the elongated substrate 100, with further metal pads 114, 124 being positioned in the spacer sections 115, which can be used to cut the elongated substrate 100 between adjacent strings 130, as symbolically indicated by dashed lines ending in opposite pairs of scissors. The SSL elements 101 may be mounted as separate chips onto the exposed portions of the conductive wires 110 and the further conductive wires 120, respectively, for example as surface mounted devices using conventional SMD mounting techniques. At the end 105 of the elongated substrate 100, a first further string 140 of SSL arrangements on the elongated substrate 100 is positioned between the spacer section 115 and the metal pads 112 connected to the conductive lines 110, the metal pads 122 connected to the further conductive lines 120, and the first further metal pads 141 connected to the first further string 140, which are typically arranged at the edge of the elongated substrate 100 to facilitate interconnection of the elongated substrate 100 with another elongated substrate as previously described. It should be noted that although in the preferred embodiment there are strings 130, 140, 150 of SSL arrangements each extending in the direction of elongation of the elongated substrate 100, it should be understood that alternative arrangements are also conceivable, such as arrangements in which strings of SSL elements 101 meander between opposite conductive lines, etc.

Fig. 5 schematically depicts a circuit diagram of a first end portion of the lighting strip 10 according to one embodiment of the invention, wherein the a-type elongated substrate 100 is interconnected to the B-type elongated substrate 100 at its facing end. Specifically, the metal pads 112 of the a-type elongated substrate 100 are interconnected to the metal pads 111 of the B-type elongated substrate 100 by the interconnects 12 (e.g., solder bumps, etc.), thereby interconnecting the corresponding conductive lines 110 of the respective elongated substrates 100. The metal pads 122 of the a-type elongate substrate 100 are interconnected to the metal pads 121 of the B-type elongate substrate 100 by the interconnects 14 (e.g., solder bumps, etc.), thereby interconnecting the corresponding further conductive lines 120 of the respective elongate substrate 100. The first further metal pads 141 of the type a elongated substrate 100 are interconnected to the second further metal pads 151 of the type B elongated substrate by the interconnects 16 (e.g., solder bumps, etc.), thereby interconnecting the first further strings 140 on the type a elongated substrate 100 to the second further strings 150 on the type B elongated substrate 100. As previously described, interconnecting the first further strings 140 of M series-connected SSL elements 101 on the a-type elongated substrate 100 to the second further strings 150 of N-M series-connected SSL elements 101 on the B-type elongated substrate 100 forms strings 130 of N series-connected SSL elements 101 distributed across two adjacent elongated substrates 100, which allows cutting of any elongated substrate 100 at the end of the distributed strings in the spacer or cutting region 150 on any of these substrates near the boundary between these substrates.

Fig. 6 schematically depicts a circuit diagram of a further end portion of the lighting strip 10 according to one embodiment of the invention, wherein the B-type elongated substrate 100 is interconnected to the C-type elongated substrate 100 at its facing end. Specifically, the metal pads 112 of the B-type elongated substrate 100 are interconnected to the metal pads 111 of the C-type elongated substrate 100 by the interconnects 12 (e.g., solder bumps, etc.), thereby interconnecting the corresponding conductive lines 110 of the respective elongated substrates 100. The metal pads 122 of the B-type elongated substrate 100 are interconnected to the metal pads 121 of the C-type elongated substrate 100 by the interconnects 14 (e.g., solder bumps, etc.), thereby interconnecting the corresponding further conductive lines 120 of the respective elongated substrate 100. The first further metal pads 141 of the B-type elongated substrate 100 are interconnected to the second further metal pads 151 of the C-type elongated substrate 100 by interconnects 16 (e.g., solder bumps, etc.), thereby interconnecting the first further strings 140 on the B-type elongated substrate 100 to the second further strings 150 on the C-type elongated substrate 100. As previously described, interconnecting the first further strings 140 of M series-connected SSL elements 101 on the B-type elongated substrate 100 to the second further strings 150 of N-M series-connected SSL elements 101 on the C-type elongated substrate 100 forms strings 130 of N series-connected SSL elements 101 distributed across two adjacent elongated substrates 100, which allows cutting of any elongated substrate 100 at the end of the distributed strings in the spacer or cutting region 150 on any of these substrates near the boundary between these substrates.

In the same manner, two adjacent B-type elongated substrates 100 may be interconnected at their facing ends, i.e., the metal pads 112 of a B-type elongated substrate 100 are interconnected to the metal pads 111 of an adjacent B-type elongated substrate 100 by interconnects 12 (e.g., solder bumps, etc.), thereby interconnecting the corresponding conductive lines 110 of the respective elongated substrates 100. The metal pads 122 of the B-type elongated substrate 100 are interconnected to the metal pads 121 of an adjacent B-type elongated substrate 100 by the interconnects 14 (e.g., solder bumps, etc.), thereby interconnecting the corresponding further conductive lines 120 of the respective elongated substrate 100. The first further metal pads 141 of the B-type elongated substrate 100 are interconnected to the second further metal pads 151 of the adjacent B-type elongated substrate 100 by interconnects 16 (e.g. solder bumps, etc.), thereby interconnecting the first further strings 140 on the B-type elongated substrate 100 to the second further strings 150 on the adjacent B-type elongated substrate 100 in order to form the distributed strings 130.

The lighting strip 10 assembled in this way may take the form of an A-B] _n Form C, which depicts a daisy chain of interconnected elongated substrates of type a, type B and type C, wherein n is a positive integer, typically a positive integer having a value of at least 5, preferably at least 8, more preferably at least 10. Thus, it is necessary to provide three different types of elongated substrates 100, for example, three different types of (flexible) PCBs. By providing a separable elongated substrate comprising an a-type elongated substrate portion and a C-type elongated substrate portion, the provision of the elongated substrate 100 used in such an assembly process can be simplified, so that only two types of different elongated substrates (a+c and B) need to be provided, since the a-and C-type elongated substrates 100 can be produced by dividing the separable a+c-type elongated substrate. Such a separable a+c type elongated substrate is generally similar to the B type elongated substrate 100 in that opposite ends of the substrate include a first additional string 140 and a second additional string 150, respectively, wherein A dicing area is provided between the a-type and C-type substrate portions, wherein each of these portions includes metal pads 111, 121 and 112, 122, respectively, adjacent to (adjacent to) the dicing area.

Alternatively, the assembled lighting strip 10 according to the teachings of the present invention may take the shape [ B ] n, i.e., there are a-type and C-type elongated substrates 100, and the opposite ends of the lighting strip 10 may be omitted. As will be appreciated by those skilled in the art, in this case, the first further string 140 at a first end of the lighting strip 10 and the second further string 150 at an opposite end of the lighting strip 10 will not be used (i.e. not be present). Preferably, the first further strings 140 at the first end of the lighting strip 10 and the second further strings 150 at the opposite end of the lighting strip 10 are unoccupied, i.e. no SSL elements 101 are mounted on these strings of the respective B-type elongated substrates 100 to be positioned at the opposite ends of the lighting strip 10, as such SSL elements 101 will remain unconnected, such that their presence will unnecessarily increase the manufacturing costs of such B-type elongated substrates 100 and lighting strips 10 comprising such substrates.

Fig. 7 schematically depicts a layout of a portion of a lighting strip 10 according to an example embodiment, wherein adjacent elongated substrates 100 are interconnected by the previously described interconnects 12, 14 and 16, forming a string 130 of N series-connected SSL elements 101 distributed across adjacent elongated substrates 100. Because the interconnects 12, 14, and 16 are positioned within the distributed string 130, the lighting strip 10 may be cut at either side of the distributed string 130 in the respective spacers or cutting regions 115. In this way, a lighting strip 10 is provided which can be cut between any adjacent pair of strings 130 of N series-connected SSL elements 101, so that the lighting strip 10 can be cut to any desired length. This increases the user flexibility of such an illumination strip 10 compared to prior art illumination strips in which the interconnects 12 and 14 are typically positioned between an adjacent pair of strings 130 of N series-connected SSL elements 101 on adjacent elongated substrates 100, such that the spacers or cut areas 115 of such an arrangement will coincide with the interconnects 12 and 14 as previously described. The spacer sections 115 are typically spaced apart at regular intervals in such an illumination strip 10, such as, for example, 5cm or 10cm intervals. The overall length of the lighting strip 10 according to embodiments of the present invention is not particularly limited, as the lighting strip 10 may take any suitable length, e.g., 5m, 50m, or more.

Embodiments of the invention are not limited to an elongated substrate 100 and a lighting strip 10 comprising such an elongated substrate, which comprises only a single SSL arrangement. For example, fig. 8 is a circuit diagram of a type B elongated substrate 100, fig. 9 is a circuit diagram of a type a elongated substrate 100, and fig. 10 is a circuit diagram of a type C elongated substrate 100, wherein the elongated substrate 100 comprises a first SSL arrangement 50 having SSL elements 101 of a first type (e.g., SSL elements generating light having a first spectral composition), and a second SSL arrangement 50 'having SSL elements 101' of a second type (e.g., SSL elements generating light having a second spectral composition different from the first spectral composition (such as light of a different color or white light having a different color temperature). In such an arrangement, each SSL arrangement 50, 50 'is connected between a dedicated conductive wire 110, 110' arranged to have a first polarity and a common further conductive wire 120 arranged to have a polarity opposite to the first polarity.

Each conductive line is connected at opposite ends to a dedicated metal pad, i.e. conductive line 110 is connected between metal pads 111 and 112, conductive line 110' is connected between metal pads 111' and 112', and conductive line 120 is connected between metal pads 121 and 122, so that when the lighting strip 10 comprising such a substrate is assembled as described before, the respective conductive line can be interconnected to the corresponding conductive line on the adjacent elongated substrate. In other words, during such assembly, the metal pads 112 of the conductive lines 110 of the first elongated substrate 100 are interconnected to the metal pads 111 of the conductive lines 110 on the adjacent elongated substrate, the metal pads 112 'of the conductive lines 110' of the first elongated substrate 100 are interconnected to the metal pads 111 'of the conductive lines 110' on the adjacent elongated substrate, and the metal pads 122 of the further conductive lines 120 of the first elongated substrate 100 are interconnected to the metal pads 121 of the conductive lines 110 on the adjacent elongated substrate. Similarly, the first further metal pads 141, 141 'of the first further strings 140, 140' of the SSL arrangements 50, 50 'on the first elongated substrate 100 are interconnected to the corresponding second further metal pads 151, 151' of the second further strings 150, 150 'of the SSL arrangements 50, 50' on the first elongated substrate 100, i.e. the first further metal pads 141 on the first elongated substrate 100 are interconnected to the second further metal pads 151 on the adjacent elongated substrate, and the first further metal pads 141 'on the first elongated substrate 100 are interconnected to the second further metal pads 151' on the adjacent elongated substrate.

Each conductive wire at its junction with the strings 130, 130 'of N series-connected SSL elements 101, 101' may comprise a further metal pad to facilitate reconnection of the cut sections of the elongated substrate 100, for example when forming part of the lighting strip 10 as described before. For example, the string 130 may be connected between the first conductive line 110 arranged to have the first polarity and the further conductive line 120 to which the further metal pads 114, 124 are connected, respectively, and the string 130' may be connected between the second conductive line 110' arranged to have the first polarity and the further conductive line 120 to which the further metal pads 114', 124 are connected, respectively. By providing each of the SSL arrangements 50, 50 'with dedicated conductive lines 110, 110' arranged to have a first polarity, each SSL arrangement can be addressed individually, such that the respective SSL elements 101 and 101 'of these SSL arrangements 50 and 50' can operate independently of each other, thereby providing a lighting strip 10 that can be configured according to its luminous output.

Fig. 11 schematically depicts an example layout of a portion of an elongated substrate 100 comprising a plurality (here two) of SSL arrangements 50, 50'. In this example embodiment, a first SSL arrangement 50 comprising a string 130 of N series-connected SSL elements 101 and a further string 140 of M series-connected SSL elements 101, and a further SSL arrangement 50 'comprising a string 130' of N series-connected SSL elements 101 'and a further string 140' of M series-connected SSL elements 101 'are positioned on the first main surface 103 of the elongated substrate 100 together with the conductive wires 110, 110' and the metal pads 112, 112', 122, 141' on the edge or end 105 of the elongated substrate 100. Additional conductive lines 120 are positioned on a major surface of the elongated substrate 100 opposite the first major surface 103. In order to connect the respective SSL elements 101, 101' to the further conductive wires 120, conductive structures, such as vias, may extend through the elongated substrate 101 in order to provide such interconnections. The positioning of all metal pads on one of the major surfaces of the elongated substrate 100 has the following advantages: interconnection of the elongate substrate 100 with an adjacent elongate substrate, for example as described previously, is readily achieved, while positioning of the further conductive wires 120 on the opposite main surface frees space on the first main surface 103 for positioning a plurality of individually controllable SSL arrangements 50, 50' thereon.

As can be seen in fig. 11, the strings 130, 130 'of the respective SSL arrangements 50, 50' on the first main surface 103 of the elongated substrate 100 are generally aligned in the elongated direction of the elongated substrate 100, such that the spacers or cut areas 115 extend across the entire width of the elongated substrate 100. Respective metal pads 114, 114' and 124 may be positioned within such spacers or cut regions 150 to facilitate reconnecting (e.g., when forming part of the lighting strip 10) the cut sections of the elongated substrate 100 to another elongated substrate, a power source, etc., e.g., using wire-to-substrate (PCB) interconnects, etc.

For example, fig. 12 is a circuit diagram of the B-type elongated substrate 100, fig. 13 is a circuit diagram of the a-type elongated substrate 100, and fig. 14 is a circuit diagram of the C-type elongated substrate 100, wherein the elongated substrate 100 includes: a first SSL arrangement 50 having a string 130, 140, 150 comprising SSL elements 101 of a first type (e.g., SSL elements producing light having a first spectral composition); a second SSL arrangement 50' having strings 130', 140', 150' comprising SSL elements 101' of a second type (e.g., SSL elements producing light having a second spectral composition different from the first spectral composition); and a third SSL arrangement 50″ having strings 130", 140", 150 "comprising SSL elements 101" of a third type (e.g., SSL elements producing light having a third spectral composition different from the first and second spectral compositions). The light with different spectral components may be different colored light and/or white light with different color temperatures. As previously described, each SSL arrangement 50, 50', 50 "is connected between its dedicated conductive wire 110, 110', 110" arranged to have a first polarity and a common further conductive wire 120 arranged to have a polarity opposite to the first polarity, so that the respective SSL arrangement can be controlled individually. In this way, the elongated substrate 100 and the lighting strip 10 assembled from a plurality of such elongated substrates 100 as explained in more detail above may comprise any suitable number of SSL arrangements thereon, such as for example a first SSL arrangement comprising white SSL elements and three further SSL arrangements comprising red, green and blue light generating SSL elements, respectively. In addition, there may be a further SSL arrangement comprising white SSL elements, thereby providing a pair of SSL arrangements comprising white SSL elements that respectively produce white light of different color temperatures (e.g. cool white light and warm white light). This may result in an illumination strip comprising such a pair of white light-producing SSL arrangements and three such further SSL arrangements producing different colours of light, wherein each SSL arrangement is individually addressable by a respective dedicated conductive wire as described above. Many other variations will be apparent to the skilled artisan.

The layout of a portion of an elongated substrate 100 comprising three individually controllable SSL arrangements on a first main surface is schematically depicted in fig. 15. The first SSL arrangement comprises SSL elements 101 and is connected between first conductive lines 110 on a first main surface and common further conductive lines 120 on an opposite main surface. As previously described, the first conductive line 110 extends between metal pads 111 and 112 on the first major surface at opposite ends of the elongated substrate. The metal pads 114 may be present in spacer areas between series-connected strings of N SSL elements to allow reconnecting such strings after cutting the elongated substrate in such areas, as described in more detail above. The second SSL arrangement comprises SSL elements 101 'and is connected between second conductive lines 110' on the first main surface and common further conductive lines 120 on the opposite main surface. As previously described, the second conductive line 110 extends between metal pads 111 'and 112' on the first major surface at opposite ends of the elongated substrate. The metal pads 114' may be present in the spacer region between the series-connected strings of N SSL elements to allow reconnecting such strings after cutting the elongated substrate in such region, as described in more detail above. The third SSL arrangement comprises SSL elements 101 "and is connected between third conductive lines 110" on the first main surface and common further conductive lines 120 on the opposite main surface. As previously described, the third conductive line 110 "extends between metal pads 111" and 112 "on the first major surface at opposite ends of the elongated substrate. The metal pads 114 "may be present in the spacer region between the series-connected strings of N SSL elements to allow reconnecting such strings after cutting the elongated substrate in such region, as described in more detail above.

As previously described, the respective SSL arrangements may be individually controlled by the respective dedicated conductive lines (i.e., the first, second and third conductive lines 110, 110', respectively) to which they are connected. Additional dedicated conductive lines may be added to the first main surface, to which additional SSL arrangements may be connected. In this way, the first major surface may carry any suitable number of individually controllable SSL arrangements, as previously described. This may be facilitated by increasing the width of the elongated substrate 100, if desired.

As previously mentioned, the connection of the SSL elements on the first main surface with the further conductive lines on the opposite main surface may be provided by connections such as vias extending through the elongated substrate 100. Preferably also on the first main surface are corresponding metal pads of the conductive lines 110, 110' and 110 "and the common further conductive line 120, i.e. metal pads 111, 111', 111", 112' and 112 "and metal pads 121 and 122. The metal pads (here metal pads 141, 141' and 141 ") of the truncated string portion (i.e. the first further string of M series-connected SSL elements and/or the second further string of N-M series-connected SSL elements) are preferably also on the first main surface. By having all metal pads positioned on the same major surface, interconnection of adjacent elongated substrates 100, such as in the lighting strip 10, is particularly simple.

Embodiments of the invention may be used with any suitable arrangement of SSL elements on an elongated substrate, such as any suitable pitch of SSL elements, e.g. a pitch equal to or smaller than 10mm. Of course, a spacing of more than 10mm is also conceivable. However, for pitches exceeding 10mm, alternative solutions (not part of the invention) may be envisaged. An example layout of this alternative solution is schematically depicted in fig. 16, fig. 16 depicting a portion of the lighting strip 10, wherein two adjacent elongated substrates 100 are soldered together by a first solder joint 12 interconnecting respective metal pads 111, 112 of a first conductive line 110, and by a further solder joint 14 interconnecting respective metal pads 121, 122 of a further conductive line 120. As previously described, the SSL elements 101 on each elongated substrate 100 are arranged in a plurality of strings 130, each string 130 comprising N series-connected SSL elements 101. The pitch P between SSL elements 101 (preferably equally spaced) is greater than 10mm. As previously described, spacers or cut regions 115 are positioned between adjacent strings 130, wherein there may be metal pads 114, 124 for reconnecting the first and further conductive lines 110, 120, respectively.

However, due to the relatively large pitch P, additional spacer regions 115 may be positioned between the strings 130 immediately adjacent or near the end or edge of each elongated substrate 100 and the metal pads 111, 121 or 112, 122 at that edge. In fig. 16, by way of non-limiting example only, the spacer region 115 is positioned between the metal pads 111, 121 and the first string 130 of the right-hand elongated substrate 100; it is equally feasible to locate this spacer region between the metal pads 112, 122 and the last string 130 of an adjacent elongated substrate 100.

To ensure that the pitch P of SSL elements 101 is maintained across the interconnected adjacent elongated substrates 100, the metal pads (here, metal pads 111, 121, as a non-limiting example only) on the elongated substrate 100 adjacent to the elongated substrate including the spacer region 115 near its edge may be positioned closer to the terminal SSL elements 101 of the final string 130 on the adjacent elongated substrate 100 (i.e. SSL elements 101 near its edge). Thus, in this embodiment, each string 130 is positioned entirely on a single elongated substrate 100, i.e. no string 130 extends across adjacent elongated substrates 100, while maintaining a constant pitch P of SSL elements 101 across the lighting strip 10, and providing spacers or cut areas 115 at regular intervals across the entire lighting strip 10. Thus, no additional interconnects are required to interconnect the M SSL elements and the N-M SSL element portions of such a distributed string 130, such that this embodiment is characterized by the absence of interconnects between interconnected adjacent elongated substrates 100, as compared to the above-described embodiment of the present invention (e.g., the absence of interconnects 16).

When interconnecting such adjacent elongated substrates 100 (e.g., forming solder bumps 12 by soldering metal pads 111 to metal pads 112 and solder bumps 14 by soldering metal pads 121 to metal pads 122), care must be taken that solder does not flow into adjacent spacer regions 115 intended for dicing, as such soldering would make such regions more difficult to dice, which is undesirable. To prevent this, as a non-limiting example, the metal pads (here, metal pads 111, 121) adjacent to the spacer region 115 are separated from the spacer region by a barrier structure 20 (e.g., a dam structure or a bump-like structure), the barrier structure 20 preventing solder applied to the metal pads from flowing from the metal pads to the adjacent spacer region 115. Such a barrier structure may be a discrete structure positioned between the metal pads 111, 121 and the adjacent spacer region 115, or alternatively may be an unexposed region of the metal pads 111, 121 proximate to the spacer region. In other words, when the metal pads 111, 121 are formed by removing the cover material therefrom, only a portion of the cover material may be removed such that the remaining cover material forms the barrier structure 20. This has the further advantage that: the area of the metal pads 111, 121 remains small, which makes it possible to selectively plate such pads with gold in order to improve the reliability of the interconnection between the elongated substrates 100.

Finally, it is noted that for the avoidance of doubt, the spacer region 115 in the foregoing embodiments (forming part of the present invention and not forming part of the present invention) symbolically depicts that two cut lines on either side of such spacer region merely indicate that such spacer region 115 may be cut on either side. This should not be interpreted to mean or imply that two cuts must be made. However, because such spacer regions 115 may be cut on either side, such spacer regions may be re-cut, for example, after a first cut and subsequent re-connection of the elongated substrate 100 including the spacer regions.

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. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "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. In a device 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.

Claims

1. An elongated substrate (100) having opposite ends (103, 105) in an elongation direction of the elongated substrate (100), and the elongated substrate (100) comprising:

a conductive line arrangement comprising conductive lines (110, 110') arranged to have a first polarity;

-a further electrically conductive wire (120) arranged with a polarity opposite to the first polarity and spatially separated from the electrically conductive wire, each of the electrically conductive wire and the further electrically conductive wire extending between the opposite ends and terminating in a respective metal pad (111, 111';112, 112';121, 122) at each of the opposite ends; and

at least one solid state lighting arrangement (50, 50', 50 "), comprising:

a plurality of strings (130, 130', 130 ") of N series-connected solid state elements (101, 101', 101"), where N is a positive integer, the strings being connected in parallel to the conductive line and the further conductive line and separated from each other by spacer sections (115); and at least one of the following:

a string (140, 140', 140 ") of M series-connected solid state elements, wherein M is a positive integer and M < N, the string being close to one of the opposite ends and being connected between the conductive line and a first further metal pad (141, 141') at the one of the opposite ends; and

A string (150, 150', 150 ") of N-M series-connected solid state elements, the string being close to the other of the opposite ends and being connected between the further conductive line and a second further metal pad (151, 151') at the other of the opposite ends;

wherein when the elongated substrate (100) is interconnected with another elongated substrate (100) having complementary strings of N-M serially connected solid-state elements and/or complementary strings of M serially connected solid-state elements, one of the strings of M serially connected solid-state elements and the strings of N-M serially connected solid-state elements on the elongated substrate is connected with a corresponding complementary string of the complementary strings of N-M serially connected solid-state elements and the complementary strings of M serially connected solid-state elements on the other elongated substrate to form a string of N serially connected solid-state elements across adjacent elongated substrates;

wherein across the adjacent elongated substrates, the strings of N serially connected solid state elements are electrically and optically identical to each of the plurality of strings of N serially connected solid state elements.

2. The elongated substrate (100) according to claim 1, wherein each string of the strings (130, 130', 130 ") of N series-connected solid state elements extends in the elongation direction of the elongated substrate.

3. The elongated substrate (100) according to any one of claims 1 and 2, wherein the elongated substrate is flexible.

4. The elongated substrate (100) according to any one of claims 1 and 2, wherein each solid state element (101, 101', 101 ") is provided as a separate chip mounted on the elongated substrate.

5. The elongated substrate (100) according to any one of claims 1 and 2, wherein the conductive line arrangement comprises: -a pair of said conductive lines (110, 110') arranged with said first polarity; and a pair of said solid state lighting arrangements (50, 50 ') comprising a first solid state lighting arrangement and a second solid state lighting arrangement, wherein a respective string (130, 140) of said first solid state lighting arrangement (50) is connected to one (110) of a pair of said electrically conductive wires arranged to have said first polarity, if connected to an electrically conductive wire arranged to have said first polarity, and a respective string (130 ', 140 ') of said second solid state lighting arrangement (50 ') is connected to the other (110 ') of a pair of said electrically conductive wires arranged to have said first polarity, if connected to an electrically conductive wire arranged to have said first polarity.

6. The elongated substrate (100) according to claim 5, further comprising a first main surface and a second main surface opposite to the first main surface, wherein a pair of the conductive wires (110, 110 ') and a pair of the solid state lighting arrangements (50, 50') arranged to have the first polarity are positioned on the first main surface and the further conductive wires (120) are positioned on the second main surface.

7. The elongated substrate (100) according to claim 6, wherein the electrically conductive wire arrangement comprises a third electrically conductive wire (110 ") arranged to have the first polarity, the elongated substrate further comprising a further solid state lighting arrangement (50"), wherein respective strings (130 ", 140") of the further solid state lighting arrangement are connected to the third electrically conductive wire if connected to electrically conductive wires arranged to have the first polarity.

8. The elongated substrate (100) according to any one of claims 1 and 2, wherein each of the conductive wires (110, 110', 110 ") and the further conductive wires (120) arranged to have the first polarity comprises a plurality of further metal pads (114, 114', 124), wherein each of the further metal pads is conductively connected to a junction point between the conductive wire and one end of a plurality of strings (130, 130', 130") of N serially connected solid state elements (101, 101', 101 ") connected to the conductive wire.

9. The elongated substrate (100) of claim 8, wherein the further metal pads (114, 114', 124) are positioned in the spacer section (115).

10. A lighting strip (10) comprising a plurality of elongated substrates (100) according to any one of claims 1-9, wherein respective substrates are interconnected by a pair of interconnects (12, 14) and a further interconnect (16), the pair of interconnects (12, 14) interconnecting the metal pads (111, 112;111', 112';121, 122) of the corresponding conductive and further conductive lines (110, 110 '; 120) at facing ends (103, 105) of adjacent elongated substrates, the further interconnect (16) interconnecting the first further metal pad (141, 141') of each solid state lighting arrangement (50, 50 ') on one of the adjacent elongated substrates to the second further metal pad (151, 151') of the corresponding solid state lighting arrangement on the other of the adjacent elongated substrates at the facing ends;

wherein across the adjacent elongated substrates, the strings of N serially connected solid state elements are the same size in the elongated direction of the elongated substrate as each of the plurality of strings of N serially connected solid state elements.

11. The lighting strip (10) of claim 10, further comprising a pair of terminal elongated substrates (100) at opposite ends of the lighting strip, the pair of terminal elongated substrates comprising:

a first terminal elongated substrate not comprising a string (140, 140', 140 ") of M series-connected solid state elements, such that a terminal end of the first terminal elongated substrate comprises only the metal pads (111, 111'; 121) of the conductive lines and the further conductive lines (110, 110', 110"; 120); and

the second terminal elongated substrate does not comprise a string (150, 150', 150 ") of N-M series connected solid state elements, such that a terminal end of the second terminal elongated substrate comprises only the metal pads (112, 112'; 122) of the conductive line and the further conductive line.

12. A method of manufacturing a lighting strip (10) according to claim 10 or 11, the method comprising:

interconnecting a plurality of elongated substrates (100) according to any of claims 1-9,

wherein the respective substrates are interconnected by a pair of interconnects (12, 14) and a further interconnect (16), the pair of interconnects (12, 14) interconnecting the metal pads (111, 112;111', 112';121, 122) of the corresponding conductive and further conductive lines (110, 110 '; 120) at facing ends of adjacent elongated substrates, the further interconnect (16) interconnecting the first further metal pad (141, 141 ') of each solid state lighting arrangement (50, 50 ') on one of the adjacent elongated substrates to the second further metal pad (151) of the corresponding solid state lighting arrangement on the other of the adjacent elongated substrates at the facing ends.

13. The method of claim 12, further comprising terminating opposite ends of the illumination strip (10) with a pair of terminal elongated substrates (100), the pair of terminal elongated substrates (100) comprising:

a second terminal elongated substrate that does not include a string (150, 150', 150 ") of N-M solid state elements connected in series, such that a terminal end of the second terminal elongated substrate includes only the metal pads (112, 112'; 122) of the conductive lines and the further conductive lines (110, 110', 110"; 120);

interconnecting respective metal pads of the conductive wires of the first terminal elongated substrate to respective metal pads of corresponding conductive wires of adjacent elongated substrates of the first terminal elongated substrate at the facing ends of the substrates, and interconnecting one or more second additional metal pads of the first terminal elongated substrate to corresponding first additional metal pads of adjacent elongated substrates of the first terminal elongated substrate at the facing ends; and

The method further includes interconnecting respective metal pads of the conductive lines of the second terminal elongated substrate to corresponding metal pads of conductive lines of an adjacent elongated substrate of the second terminal elongated substrate at the facing ends of the substrates, and interconnecting one or more first additional metal pads of the second terminal elongated substrate to corresponding second additional metal pads of an adjacent elongated substrate of the second terminal elongated substrate at the facing ends.

14. The method of claim 12 or 13, wherein the interconnection comprises soldering.