EP2695010A2

EP2695010A2 - Circuit board element having at least one led

Info

Publication number: EP2695010A2
Application number: EP12718028.9A
Authority: EP
Inventors: Alexander Kasper; Gregor Langer
Original assignee: AT&S Austria Technologie und Systemtechnik AG
Current assignee: AT&S Austria Technologie und Systemtechnik AG
Priority date: 2011-04-01
Filing date: 2012-03-20
Publication date: 2014-02-12
Also published as: CN103562762A; AT12749U1; US20140233241A1; KR20140027210A; US9903539B2; KR101922206B1; WO2012129580A3; WO2012129580A2

Abstract

The invention relates to a circuit board element (1) comprising a substrate (2), on which at least one dielectric layer (7) is arranged, and at least one LED (light-emitting diode) (10), wherein at least one channel-shaped waveguide cavity (11) leading away from the LED (10) is provided in the dielectric layer (7), which waveguide cavity leads to at least one integrated light-sensitive component (12), preferably a photodiode or photocell, arranged for examining the light emission, wherein the LED (10) is preferably also arranged in a cavity (9) that is connected to the waveguide cavity (11). The invention further relates to a method for producing such a circuit board element (1).

Description

Printed circuit board element with at least one LED

The invention relates to a printed circuit board element with a substrate, on which at least one dielectric layer is arranged, as well as with at least one LED (light emitting diode).

Furthermore, the invention relates to methods for producing such a printed circuit board element.

Not least in view of the restrictions on the production and use of incandescent lamps for economic and environmental reasons, lighting systems with light emitting diodes, in short LEDs (LED light emitting diodes), are becoming increasingly interesting. It is also important that the technical advances in LED technology mean that LEDs are no longer merely meaningful as display elements on devices, but are also becoming increasingly interesting for other applications, such as for flat screen TVs, but also for lighting systems. Modern LEDs not only have sufficient

Brightness, they are also favorable from the manufacturing cost ago and are now used on a large scale, for example in lighting systems in motor vehicles.

Typically, LEDs emit a particular color (that is, with a certain wavelength, with a more or less narrow bandwidth), and by mixing can be a variety of colors to white light, and here again turn to a cold white light or a warm white light, reach. The techniques for this are well known and require no further explanation. Just as an example

mentions that with a red, a green and a blue LED with a corresponding control and thus mixture white light can be obtained. To control pulse width modulation (PWM) is preferably used, with which the current is modulated by the LEDs. The longer the current pulses are, the brighter the LEDs shine. In this case, these LEDs are in the mixing of various ^¬ denfarbigen LEDs also different to control to achieve the desired mixed color. However, this mixing ratio changes during the lifetime of the LEDs, so that the Mixed color changes, which ultimately leads to an undesirable result. A color change can also be caused by different ambient temperatures, for example at relatively high temperatures.

It is therefore already state of the art to monitor light generated by LEDs continuously with the aid of sensors and to adjust the LED currents as a function of the changes in the respective light color and also of the temperatures. For example, reference may be made in this connection to EP 2 082 620 Bl.

Disadvantage is in the known solutions, where the emitted light, such as white LED light, which is emitted in the combination of red, green and blue LEDs, is detected by means of a sensor to supply an electrical actual signal to the control unit, that these circuits including sensor are provided in a separate device, such a monitoring or control circuit not for all applications, eg in miniaturized circuits with LEDs, is readily applicable. It would be necessary at intervals to measure such LED units in laboratories or the like, so that a continuous readjustment of the LED light is not possible.

The object of the invention is therefore to remedy this situation and in a simple and cost-effective way capturing the abgege ^¬ surrounded LED light - no preference in which color, whether mixed light (white light) of RGB LEDs (RGB - Red Green Blue) or only by individual LEDs - to detect directly at the location of the LEDs, to then evaluate the measurement result immediately via a monitoring ^¬ or control circuit and to allow readjustment of the power supply of the LEDs, preferably via PWM. So an integrated system should be made possible to allow this monitoring with readjustment.

To solve this problem, the invention provides a printed circuit board element as defined in claim 1. Advantageous embodiments and developments as well as advantageous methods for producing such a printed circuit board element are in the specified dependent claims.

In the case of the present printed circuit board element, a channel-shaped optical waveguide cavity is thus present in the dielectric layer which leads away from the LED to form an integrated photosensitive component which is arranged to check the light emission and which forms part of a monitoring or control circuit. This component is preferably formed by a photodiode or a phototransistor or the like. Photosensor. Of course, in the case of a plurality of LEDs, correspondingly a plurality of photosensitive detector elements are to be provided, which if necessary can also be formed by a single multiple detector with a plurality of receiving areas. In operation, light is supplied to these photosensitive components by the LEDs in a "bypass" manner via the optical waveguide in the waveguide cavity, so that the respective LED light can be detected directly in place, within the printed circuit board element itself, which is brightness and color, etc. The measured values thus acquired can be compared, preferably after digitization, with nominal values which can be stored in a controller chip, so that in the case of deviations a readjustment of the current drive for the LEDs can be carried out Components can be formed in a conventional manner and above all be arranged directly on the same circuit board element in conventional technology, so that advantageously an integrated correction of colors and brightnesses of LEDs can be made directly on the circuit board element.

Preferably, the respective LED or an LED chip is accommodated in a cavity in the dielectric layer material, wherein the waveguide cavity directly adjoins the LED cavity. The waveguide cavity is filled to form the optical waveguide, in particular with an optical material which is introduced in the wet state.

The present technique allows further miniaturization because the optical fiber connection between LED and photosensitive device (photodiode) is very close Arrangement of these components allowed together. The integration of the LED component on the one hand and the sensor system or control circuit in one and the same circuit board element

On the other hand, even in miniaturized applications, with limited space, allows continuous control and readjustment of the LED light. The cavities for the optical waveguide and preferably also for the LED and furthermore, as it is likewise preferred, for the photosensitive component, that is to say in particular the photodiode, also make it possible to utilize light reflection; Another advantage results from the fact that even in the dimension relatively small encapsulations, as provided for the protection of the components are possible. Furthermore, the design possibilities are increased.

As far as the mentioned light reflection is concerned, it is advantageous if the top of the waveguide, i. the top of the optical material, with a reflective layer, e.g. with solder mask, is covered.

Furthermore, it is advantageous if the walls of the waveguide cavity to increase the reflectivity, for the production of electrical connections and / or for the preparation of fillets or the like. especially metallic, e.g. coated with copper or gold, if necessary with solder mask.

For certain reflection effects, it is also advantageous if the walls of the waveguide cavity and / or optionally the LED cavity are formed obliquely.

As mentioned, it is provided in a favorable embodiment that the photosensitive component is mounted in a cavity of the dielectric layer. Alternatively, it is also advantageous if the photosensitive component is arranged on the layer having the waveguide cavity, wherein the waveguide cavity then extends below this component.

In order to remove heat from the arrangement, it can also be advantageously provided that the waveguide cavity having Layer on a heat dissipating layer, for example made of aluminum, is attached. Furthermore, it is possible here that the substrate consists of heat-dissipating material, for example of aluminum.

A manufacturing technology favorable embodiment of the printed circuit board element is further characterized by the fact that the waveguide cavity is limited by a printed on the substrate or a dielectric layer frame.

For producing a printed circuit board element as stated above, it may be preferred to proceed such that on a finished processed substrate, if necessary a heat dissipating plate, a prefabricated printed circuit board layer, for example, to form an elongate cavity opening, for the production of the channel-shaped waveguide. a prepreg is applied, after which in the opening of the waveguide and optionally. The LED and or or the photosensitive component are attached.

On the other hand, in order to produce such a printed circuit board element, it is often also advantageous if a dielectric layer is applied to the substrate in which, e.g. by laser structuring and removing defined areas, or by pressing, for example by means of stamp printing, a cavity is attached at least for the channel-shaped waveguide.

Furthermore, for ease of manufacture, it is also advantageous if a frame surrounding a cavity is printed on the dielectric substrate, e.g. by screen printing, ink printing, stencil printing or the like. Druckverfahren-.

In the above cases, the waveguide cavity to be filled with play ^¬ screen printing, doctor blading, by inkjet printing or the like. Technique with an optical material (in the wet state).

Preferably, the upper side of the waveguide can be covered with a re ^¬ inflecting layer. In a simple exporting ^¬ tion solder resist is used for the reflective layer, which can be used at the same time for other purposes in the manufacture of the printed circuit board element.

Furthermore, it is favorable if the walls of the waveguide cavity are to increase the reflectivity, e.g. with solder mask, coated.

As mentioned, the photosensitive component, that is, preferably a photodiode or photocell, may be mounted in a cavity in the dielectric layer or on the dielectric layer; in the latter case, the photosensitive component partially covers the waveguide cavity.

It should be noted that photoelectric structures or printed circuit board elements with waveguides are widely known, cf. e.g. JP 2005-195991, AT 413 891 B, AT 505 834 B, AT 503 027 B or US 2009/074354 Al; In this case, however, there are no checking structures, in particular not those with cavities in a dielectric layer.

The invention will be further explained with reference to preferred embodiments shown in the drawings, to which, however, it should not be limited. In detail, in the drawing:

1 and 2 show an inventive printed circuit board element (or the essential part hereof) in a schematic plan view (FIG. 1) or in a schematic sectional illustration (FIG. 2);

Fig. 3 to 9 different stages in the manufacture of a guide element according to FIGS. 1 and 2, wherein

Fig. 3 and 4 show prefabricated individual elements still in a separate state in plan view and in section;

Figures 5 and 6 show, in section, the following steps in uniting the individual elements and the application of standard LP (printed circuit board) processes; further Fig. 7 and 8 in plan view and in section an intermediate product of the printed circuit board element, still without components, illustrative ^¬ Chen;

Fig. 9 shows a further intermediate step in section;

10 and 11 show a modified embodiment of the printed circuit board element according to the invention in a schematic plan view (FIG. 10) or in a schematic section (FIG. 11);

Fig. 12 and 13 in corresponding representations, namely in

Top view (Figure 12) or in section (Figure 13), yet another variant of the present printed circuit board element; and

Figs. 14 and 15, also in corresponding representations

(Top view or section) a further embodiment of the printed circuit board element according to the invention.

In the drawing, the respective printed circuit board element is continuous (or of interest here part thereof) designated with 1 ^¬ net. As shown in Fig. 1 and 2 seen, at the present printed circuit board element 1 on a substrate 2, a herkömmli ^¬ ches circuit board substrate or, if necessary, for the purpose of heat dissipation, can be an aluminum substrate, an insulating or dielectric layer 3 and above in the illustrated embodiment a first conductor layer 4, for example made of copper, provided, which is already structured according to FIGS. 1 and 2.

On this circuit board part 5, for example, another circuit board part 6, without substrate, namely with dielectric layer 7 and conductor layer 8, attached. Again, the Lei ^¬ terlage 8 is already structured.

The dielectric layer 7 has an example ^¬, in plan view circular cavity 9 for receiving at least one LED or at least an LED chip 10th Adjoining this cavity 9 is a channel-shaped optical waveguide cavity 11 which extends below a photosensitive optoelectronic component. ments 12, for example in the form of a photodiode or a phototransistor, generally sensor runs.

In the cavity 11, there is a waveguide material, and the waveguide 11 'thus formed may, for example, lead to the LED chip 10, but it is also sufficient to guide the waveguide 11' to just short of the LED chip 10 and hie him there at a distance - to let go of.

As shown in FIG. 2, in the example shown, the photodiode 12 is mounted on the upper conductor layer 8, whereas the LED chip 10 is mounted on the lower conductor layer 4.

The LED 10 is encapsulated in a synthetic resin drop 13 (an encapsulation known per se by the term "Glob-Top" in the prior art). Such glob tops are e.g. provided for a mechanical protection for LED chips and ribbon wire connections, but also because of the lens effect

(Light control) and / or as a matrix for particles (for example phosphorus) for color adjustment of the light, for white-light applications, for example.

The emission direction of the LED 10 is, for example, substantially perpendicular to the main plane of the printed circuit board element 1, but a light component from the LED 10 also passes through the optical waveguide 11 'in the cavity 11 extending at an angle to this main emission direction to the photosensitive component 12 (hereinafter the FIG For the sake of simplicity, reference has always been made in this connection to a photodiode 12, but it should be clear that other photosensitive sensors or components are also suitable).

The photodiode 12 is now part of a monitoring or control circuit, which is not shown in the following, but can be accommodated on the circuit board element 1 with its components in a conventional manner.

If the light emission of LED 10 changes character over time, for example, the color changes from white to thin Red, green or blue shifts, assuming that the white light is composed of red, green, blue light or on the LED chip 10, three such single LEDs for red, green and blue are attached, so this is Displacement in the optical range by means of the photosensor 12 and the photosensors detected, with a corresponding electronic signal is obtained, which is supplied to a known control circuit for setting a drive or driver stage for the LED 10. Incidentally, an undesired change in the light emission can also result from the fact that the synthetic resin material of the encapsulation 13 changes over time (for example, a reduction in the transmission).

As mentioned, the other components of this monitoring and control circuit can be mounted in conventional printed circuit board technology, which is therefore not illustrated in detail in the drawing for the sake of simplicity. Also, throughout the drawings, the conductive pattern (e.g., 4, 8) of the printed circuit board substrates is only partially indicated or omitted altogether.

Furthermore, in the drawing, for the sake of simplicity, further steps or layers, such as further printed circuit board layers and / or protective layers or cover layers etc., have been omitted.

For producing a printed circuit board element as shown in FIGS. 1 and 2, for example - cf. 3 and 4 - a prefabricated upper circuit board "part" 6, such as a prepreg (as shown), or a core or a fully processed circuit board, mounted on the lower circuit board "part" 5 by pressing and / or gluing. The printed circuit board "part" 5 may be a fully processed FR4 printed circuit board element, IMS, etc., but also a heat dissipating plate.

To be pressed or glued upper circuit board part 6 is, for example by laser cutting, punching or the like. Techniques, so prefabricated that at least the Kaviteit 11 for the optical waveguide 11 '(see Fig. 2) is provided. The component cavity 9 for the LED 10 is preferably provided in addition to the waveguide cavity 11, which adjoins the component cavity 9 (see FIG. 3). According to Fig. 5, the circuit board parts 6 and 5 are now pressed or glued together. This is followed by standard printed circuit board processes, in particular the structuring of the conductor layer 8, cf. 6, wherein the layer 8 can be connected to the layer 4, cf. the vertical cladding 14 in Fig. 6. Further, the walls of the cavities 9, 11 formed may be coated, not only to produce an electrical connection (see the cladding 14 in Fig. 6), but also to to increase the reflectivity, and / or to rounding, such as mirror elements to bring. For these coatings of the walls of the cavities 9, 11, metals, such as copper, gold, but also Lötstopplack and the like. Materials can be used.

Thereafter, as shown in FIGS. 7 and 8, an optical material 15 is filled in the waveguide cavity 11, for example, by screen printing, doctoring, inkjet techniques or the like. The optical waveguide 11 'thus formed with the optical material 15 may thereafter be provided, as desired, with a reflective layer 16, e.g. a Lotstopplack, be covered.

This is followed in the present embodiment, the assembly with the LED chip 10 and with the photodiode 12, see Fig. 1 and 2, and then the glob-top encapsulation is still 13 made.

Various modifications and modifications are possible within the scope of the invention. Thus, the conductor layer 8 serve as a Entflechtungslage, and the conductor layer 4 can for the removal of

Loss of heat are used. The printed circuit board substrate 5, 6 may also include more than the two metallic conductor layers 4, 8 shown.

In a modification of the sequence of the steps according to FIGS. 7 to 9 and the subsequent assembly of the components (FIGS. 1 and 2), it is also possible to proceed in such a way that the waveguide material 15 is applied only after component assembly. Further For example, the cavities 9, 11 can also be produced only after attaching the printed circuit board part 6 to the printed circuit board part 5 underneath. The cavity 9, in which the LED chip 10 is mounted, does not necessarily have to form the boundary of the glob-top encapsulation 13; rather, this encapsulation 13 can also be dimensioned larger or smaller than the cavity 9 in diameter. Furthermore, the cavity 9 can also be filled with solder mask after the LED assembly and before the glob top application in order to increase the reflectivity.

Moreover, the walls of the cavities 9, 11 can be formed obliquely, for example by a corresponding drilling process in the case of the cavity 9, by a flow of the prepreg (printed circuit board part 6) during pressing and the like techniques.

It is further possible to mount a dielectric layer 7 on the substrate 2, and thereafter in this dielectric

Layer 7, the respective cavity 11 or 9, 9 'in retrospect, e.g. by laser structuring and removal of the corresponding areas, or else by pressing, for example by means of stamp printing to install.

Incidentally, the cavities 9, 11 may also be formed by a per se known technology, such as e.g. described in WO 2008/098271 AI. The waveguide material 15 may be a transparent polymer waveguide material, which is introduced into the cavity 11 in the wet state.

Of course, if an LED 10 and a photodiode 12 are shown in the drawing, it is conceivable that a plurality of LEDs 10 and a plurality of photodiodes 12 (or multiple LEDs and / or multiple detector elements) may be mounted on the printed circuit board element 1 , Conventionally, plated through-holes (PTAs) or vias may also be provided, and LED 10 and photodiode 12 may be mounted on opposite sides except on the same side. For a multiple LED control, a corresponding number of waveguides 11 'can also be provided. Additional coatings can be made by wet process or by PVD or CVD (chemical or physical vapor deposition) processes.

As further shown in Figures 10 and 11, the LED chip 10 and the photodiode 12 may be mounted on the same conductor layer 4 (see Figure 2); Furthermore, the photodiode 12 may also be provided with a glob-top encapsulation 13 '. For this purpose, a corresponding cavity 9 'for the photodiode 12 or its encapsulation 13' is to be provided in the dielectric layer 7.

The optical waveguide 11 'and the glob top 13 of the LED 10 or, as shown in FIGS. 12 and 13, the optical waveguide 11' and a modified encapsulation 13 '' of the photodiode 12 can be made of the same material and applied in a single process step using a dispenser, inkjet or capillary method.

Finally, in FIGS. 14 (top view) and 15 (schematic section), an embodiment of the present printed circuit board element is shown, in which the cavities 11 and 9, 9 'are formed by forming a raised, comparatively thin frame 17 on the dielectric layer 3 mounted on the substrate 2 is printed. As a printing process are, for example, screen printing, ink printing, but also stencil printing or the like. Printing techniques.

Incidentally, from FIGS. 14 and 15, in turn, the already structured conductor layer 4, for example made of copper, can be seen. Furthermore, in the case of the printed circuit board element 1 according to FIGS. 14 and 15, it is preferable to equip it with the components (LED 10, photodiode 12) in retrospect, after the frame 17 has been printed on.

It should also be mentioned with reference to FIGS. 14 and 15 that the optical layer 15, ie the optical material 15 (cf., for example, FIG. 8), has not been shown so as to clarify the frame 17. Of course, after imprinting the frame 17, ie after reaching the state as in FIGS. shows, still the realization of the waveguide 11 'perform as described above.

Claims

Claims:

1. printed circuit board element (1) with a substrate (2) on which at least one dielectric layer (7) is arranged, and with at least one LED (light emitting diode) (10), characterized marked ^¬ characterized in that in the dielectric layer (7) at least one of the LED (10) leading away channel-shaped waveguide cavity (11) is provided which leads to at least one integrated photosensitive, arranged to check the light emission device (12).

Second printed circuit board element (1) according to claim 1, characterized in that the LED (10) is preferably also in a Kova (9), which is connected to the waveguide cavity (11).

3. printed circuit board element (1) according to claim 1 or 2, characterized in that the waveguide cavity (11) with an optical material (15) is filled.

A circuit board element (1) according to claim 3, characterized in that the top of the optical material (15) is provided with a reflective layer (16), e.g. Solder mask, covered.

5. printed circuit board element (1) according to one of claims 1 to 4, characterized in that the walls of the waveguide cavity (11) and or or optionally. The LED cavity (9) to increase the reflectivity, for the production of electrical connections and / or for the preparation of fillets or the like. especially metallic, e.g. coated with copper or gold, if necessary with solder mask.

6. printed circuit board element (1) according to one of claims 1 to 5, characterized in that the walls of the waveguide cavity (11) and or or optionally. The LED cavity (9) are formed obliquely.

7. printed circuit board element (1) according to one of claims 1 to 6, characterized in that the photosensitive element (12) is mounted in a cavity (9 ') of the dielectric layer (7).

8. printed circuit board element (1) according to one of claims 1 to 6, characterized in that the photosensitive component (12) on the ellenleiter cavity (11) having layer (7) is arranged, wherein the waveguide cavity (11) to extends below the component (12).

Circuit board element (1) according to one of Claims 1 to 8, characterized in that the layer (7) comprising the waveguide cavity (11) is formed on a heat dissipating layer, e.g. made of aluminum, is attached.

Circuit board element (1) according to one of Claims 1 to 9, characterized in that the substrate (2) is made of heat dissipating material, e.g. made of aluminum.

11. printed circuit board element (1) according to one of claims 1 to 10, characterized in that the photosensitive component (12) is a photodiode or a photocell.

12. printed circuit board element (1) according to one of claims 1 to 11, characterized in that the waveguide cavity (11) by a on the substrate (2) or a dielectric layer (3) printed frame (17) is limited.

13. A method for producing a printed circuit board element (1) according to one of claims 1 to 11, characterized in that on a finished processed substrate (2; 5), optionally a heat dissipating plate, one to form an elongated cavity opening ( 11), for the production of the channel-shaped

Waveguide (11 '), prefabricated printed circuit board layer (6), e.g. a prepreg is applied, after which the waveguide (11 ') and optionally the LED (10) and / or the photosensitive component (12) are mounted in the opening.

14. Method for producing a printed circuit board element (1) according to one of claims 1 to 11, characterized in that on the substrate (2) a dielectric layer (7) is mounted, in which, for example by laser structuring and removing defined areas, or by pressing, for example by means of stamp pressure, a cavity (11 ) is attached at least for a channel-shaped waveguide (11 ').

Method for producing a printed circuit board element (1) according to one of Claims 1 to 12, characterized in that a frame (17) surrounding a cavity (11) is printed on the substrate (2) from a dielectric, e.g. by screen printing, ink printing, stencil printing or the like. Printing process.

A method according to any one of claims 13 to 15, characterized in that the waveguide cavity (11), e.g. by screen printing, knife coating, inkjet or the like., Is filled with an optical material (15).

A method and claim 16, characterized in that the top surface of the optical material (15) is provided with a reflective layer (16), e.g. Lötstopplack, is covered.

18. The method according to any one of claims 13 to 17, characterized in that the walls of the waveguide cavity (11) to increase the reflectivity, if necessary. Be coated with solder mask.

19. The method according to any one of claims 13 to 18, characterized in that the photosensitive component (12) on the dielectric layer (7), partially covering the waveguide cavity (11), is applied.