WO2015144393A1 - Lighting device with cob area - Google Patents

Abstract

The invention relates to a lighting device (11) comprising at least one CoB area (12) with at least one semi-conductor light source chip (17) applied to a printed circuit board (13). The at least one semi-conductor light source chip (17) is covered by means of a CoB suitable light-transmitting casting compound (19) and the CoB suitable light-transmitting casting compound (19) is covered on the light emission surface (20) thereof with a cover material (22) which is light-transmitting and which is cast thereon. The invention can also be used on lighting modules, in particular LED modules.

Description

description

The invention relates to a lighting device comprising at least one CoB region with at least one semiconductor light source chip applied to a printed circuit board, wherein the at least one semiconductor light source chip is covered by a CoB's own transparent potting compound. The invention is particularly applicable to lighting modules, in particular LED modules.

A CoB ("chip-on-board") module is typically understood to mean a printed circuit board which has at least one (CoB) region on its front side

light-emitting semiconductor chip is fitted in the form of an LED chip. As LED chips are in this sense

In particular, watch unpackaged LED chips, i. one

Semiconductor element without this surrounding potting compound

(typical examples of packaged LEDs are radial LEDs or SMD LEDs) The LED chips are often covered with a CoB proprietary potting compound, which is a transparent

Base material with phosphor as filler contains. The phosphor emits the light emitted by the LED chips

Primary light at least partially in secondary light

converted to different wavelengths. The phosphor can also serve as a litter material. During operation of the CoB module, the front, free surface of the CoB's own potting compound serves as a surface-emitting CoB emission surface ("light emission surface")

Light emission surface Mixed light with proportions of primary light and secondary light emitted. The mixed light in this case has a sum color location whose position in a color space depends on the respective proportions of the contributing light colors. Transparent or transparent silicone is known as the basic or matrix material of CoB's own potting compound. The material properties of the silicone (or another translucent

Matrix material) aim in particular at a good spreadability of the phosphor as well as at a sufficiently high flowability, since a compliance of a same

Layer thickness on the semiconductor light source chips for

Producing a constant sum color location of the

Lichtabstrahlfläche radiated mixed light is desired. However, such a matrix material is rather soft and thus less resistant to mechanical

Stress. This can in extreme cases to a

Penetration of the CoB's own potting compound with a

come electrically conductive object, which can then touch a semiconductor light source chip or a conductor track. This is particularly disadvantageous when the tracks carry high voltages, e.g. in an AC operation, in particular network operation, the semiconductor light source chips. In addition, the CoB proprietary potting compound offers often insufficient protection against environmental influences such as noxious gas, salt, moisture, dust, fingerprints, etc.

To provide improved protection of the CoB light emitting surface without affecting the optical

Efficiency is a coverage of the light emitting surface through a transparent glass plate or plastic plate of e.g. Polycarbonate or polymethyl methacrylate (PMMA) known.

However, this measure is relatively expensive. So must be provided on the circuit board for securing the plate mounting elements. Another disadvantage is that typically one or more gaps form between the CoB light emitting surface and the plate, which reduce optical efficiency by light reflections.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art, and in particular to improved protection of the CoB radiation surface without affecting the optical efficiency

provide.

This object is achieved according to the features of the independent claims. Preferred embodiments are

in particular the dependent claims.

The object is achieved by a lighting device comprising at least one CoB region with at least one semiconductor light source chip applied to a printed circuit board, wherein the at least one semiconductor light source chip is covered by a CoB own translucent potting compound and the translucent potting compound at its Lichtabstrahlfläche of a shed on it

translucent cover material is covered.

In particular, potting compounds which are specially provided for potting CoB chips are considered as CoB proprietary potting compound. Furthermore, this may be a potting compound, which covers a COB area and is spatially delimited by a further potting compound, which is provided to cover other electronic components.

This lighting device has the advantage that the light emitting surface through the translucent

 Covering material is protected. As a result, both the CoB's own translucent potting compound, the at least one semiconductor light source chip covered by it as well as possibly further located below the light emitting surface

Functional elements such as electrical and electronic

 Components (e.g., ohmic resistors) and / or traces, etc. are protected. In that the translucent

Covering material is also castable, it is as a further advantage directly or without gaps on the

Light emission surface of the CoB's own translucent

Potting compound, whereby reflection losses are suppressed and a high optical efficiency can be achieved. In addition, no support elements or the like. needed, so this one Type of protection is particularly simple, compact and inexpensive to implement. The type of potting is basically not limited. Preferably, the at least one

 Semiconductor light source chip at least one LED chip. If there are more than one LED chip, they can be lit in the same color or in different colors. A color may be monochrome (e.g., red, green, blue, etc.) or multichrome (e.g., white). Also, the light emitted by the at least one LED chip may be an infrared light (IR LED) or an ultraviolet light (UV LED). Several LED chips can produce a mixed light; e.g. a white mixed light. The at least one LED chip can have at least one

wavelength-converting phosphor included (conversion LED). The phosphor may alternatively or additionally

away from the light emitting diode ("Remote

Phosphor ") Several LED chips can be mounted on a common substrate (" submount ") Instead of or in addition to inorganic LED chips, eg based on InGaN or AlInGaP, organic LED chips (OLEDs, eg polymer Alternatively, the

at least one semiconductor light source chip e.g. have at least one diode laser chip.

It is an embodiment that the CoB region is laterally surrounded by a dam which extends beyond the CoB region

projecting, wherein the covering material is filled in the dam. The dam achieves an encircling lateral boundary around the CoB area, which in particular can serve to hold the cover material therein (especially during a potting process) and to prevent a lateral flow-off of the cover material. In other words, since the dam projects forward beyond the CoB area, in other words higher than the CoB area, a minimum layer thickness of the masking material on the front of the CoB area can be ensured. The dam also allows a predetermined adjustment of the layer thickness over the entire Area of CoB's own potting material. The dam can also be referred to as a side wall or boundary ring.

The dam can on the inside one or more for particularly accurate adjustment of the filling height of the covering

 Having filling aids, e.g. circumferential edges, steps or inward protrusions.

It is an embodiment that the dam is placed on the circuit board, on which also the at least one

 Semiconductor light source chip rests. This allows the

Printed circuit board can be used as a position reference, so that the layer height of the cover over the CoB's own translucent potting compound can be set exactly with simple means. Especially in this case like the

Luminous device on or the CoB module itself.

In general, the lighting device may be a CoB module in which the cover material is added after completion of the CoB area. This can e.g. a touchdown or

 Attach the dam on or on the circuit board.

It is an alternative education that the

Lighting device has at least one CoB module. This may in particular include a lighting device, which

has at least one prefabricated CoB module. The CoB module may, for example, on a pad of the

Lighting device may be arranged, e.g. with the back of its printed circuit board attached to the pad, e.g. be glued to it. In particular, the dam may laterally encompass the entire CoB module. This has the advantage that not only the light emission surface of the CoB module is protected by the cover material, but also all other exposed surfaces of the CoB module. For example, located outside the CoB area

Components (eg electrical and / or electronic components such as driver chips and / or circuit board) of the CoB module be shed with the cover, which further increases a touch security etc.

It is another embodiment that the

Refractive indices of the covering material and the CoB's own translucent potting compound same. As a result, reflection losses at the interface between covering material and potting compound are kept particularly small. The fact that the refractive indices are the same may include in particular that the value of the refractive index of the covering material does not deviate by more than 10% from the value of the refractive index of the CoB's own encapsulant, in particular not more than 5%, in particular not more than 2%. in particular not more than 1%. In particular, the two refractive indices may be identical or virtually identical.

It is a further embodiment that the covering material has a greater hardness than the CoB's own

translucent potting compound. Thus, a particularly good protection against mechanical stress of the

 Covering material can be achieved. The cover material can also be kept very thin. In addition, harder materials tend to have less stickiness. As a result of the greater hardness, contamination of a free light-radiating surface of the lighting device can be prevented, in particular by lint and dust particles adhering thereto. Furthermore, harder materials tend to have higher chemical resistance

To have environmental influences.

It is also an embodiment that the covering material (22) has a Shore A hardness of at least 60, in particular of at least 70. The hardness according to Shore-A of CoB's own translucent

Potting compound, however, is not more than 30, in particular not more than 20. It is also an embodiment that the dam surrounding the CoB area laterally split. So the dam can simply be arranged around the CoB area, eg on one

Pad are placed on which also rests the CoB area. The gap can flow into the gap when filling the covering material in the dam and fix the dam so laterally against the CoB area.

It is also an embodiment that the

Lighting device a lid with a

 Light passage opening, which light passage opening is located in front of the light emitting surface of the CoB area and wherein an edge of the light passage opening extends above a lid facing the front side of the dam. In the case of a plan view from above into the light passage opening, the dam thus projects laterally into the light passage opening and also extends laterally outside the light passage opening. A vertical projection of the contour of the light passage opening extends in yet other words so on the dam. In a hollow cylindrical dam and a circular light passage opening, the edge of the light passage opening is thus above the

circular top surface of the dam. As a result, after placing the cover spaced or gap-prone to the dam (the dam so the lid does not touch) just

 Sealant be placed in the gap between the lid and the dam, whereby this gap is reliably sealed.

It is a preferred embodiment for achieving a high luminous efficacy and efficiency that the cover material comprises or is transparent material. For example, the cover material may be transparent silicone.

It is a preferred embodiment for increasing the homogeneity of the emitted light that the covering material comprises transparent base or matrix material in which scattering particles are distributed as filling material. The Stray particles can be, for example, white pigments, trapped air bubbles or small hollow spheres, eg of glass. In particular, the scattering particles may not be wavelength-converting scattering particles, that is, they can not also serve as phosphors.

It is one to increase the life of the

Abdeckmaterials preferred embodiment that the

Covering material has or is heat and blue light stable material.

It is also an embodiment that the cover material comprises or is silicone. Silicone is cheap,

harmless, transparent available, castable and heat and blue light stable. The cover material may therefore consist of transparent silicone with or without scattering particles.

It is a development that the silicone is self-adhesive silicone. As a result, the surfaces to be covered, in particular the potting compound of the CoB range, do not need

pretreated to ensure good adhesion of the silicone to it. This is particularly advantageous when the CoB's own translucent potting compound is silicone or has as a base material.

In the event that the silicone is not self-adhesive or the covering material is not a silicone-based covering material, it is preferred that the light-emitting surface of the CoB region or the CoB-own potting compound is plasma-treated or is. For example, an N 2 plasma treatment or a plasma coating with e.g. Hexadimethylsilan precursor be made in the case of non-self-adhesive silicones and 02 plasma treatment in the case of non-silicone-based covering materials.

The cover material is not limited to silicone. For example, the cover material may also be or have polyacrylic polyurethane copolymer, ABS and / or PMMA. It is one for a good adhesion and a low one

Materialmismatch preferred training that the

Cover material and the CoB proprietary potting material of the same base material or material type, e.g. both have silicone. The base material, e.g. Silicone, the two materials may be varied, e.g. soft silicone for the CoB proprietary potting material and harder silicone for the masking material.

It is still an embodiment that the cover material has a layer thickness between one and ten millimeters. This represents a preferred compromise between a small volume of material, especially a small one

Layer thickness, and a sufficient protective effect.

It is a further embodiment that the covering material has a curved free surface. The free

Surface like, for example, a convex or concave

be trained surface. Due to the curved surface, the covering material likes a lens function for beam shaping of the light passing through the covering material

receive . It is yet another embodiment that the dam has a wall thickness between one and ten millimeters.

The dam may be made of plastic, especially white or translucent, e.g. transparent, plastic.

The material of the dam is preferably inexpensive, harmless, heat stable and / or blue light stable. The material of the dam may be, for example, silicone or polyacrylic polyurethane copolymer.

It is for secure attachment or connection of the

Cover material with the dam preferred that the material of the dam and the cover material are the same or similar. Under A similar material may, for example, have the same basic material type (eg silicone in a varied version, eg soft or hard) or, for example, a similar basic material

different (including none) filler

be understood.

The lighting device may be a lamp, a lamp or a module ("light module") The above-described characteristics, features and advantages of this invention as well as the manner in which they are achieved will become clearer and more clearly understood

In connection with the following schematic description of exemplary embodiments that are associated with the

Drawings are explained in more detail. It can to

 Clarity identical or equivalent elements must be provided with the same reference numerals.

Fig.l shows a sectional view in side view a

 Lighting device according to a first

 Embodiment; and

2 shows a sectional side view of a

 Lighting device according to a second

 Embodiment.

Fig.l shows a sectional view in side view of a lighting device in the form of a lighting module 11. Das

Luminous module 11 has a CoB region 12 with a

plate-shaped circuit board 13. At the front 16 of the circuit board 13 are several

 Semiconductor light source chips in the form of LED chips 17. Such an arrangement is also referred to as a "chip-on-board" or "CoB" arrangement. The light module 11 may also be referred to as a "CoB module." The circuit board 13 may be referred to as

Base material, for example, conventional board base material such as FR4, etc. or have a base made of ceramic. The circuit board 13 may also be a metal core board. The LED chips 17 are surrounded by a CoB-own ring 18 having a hollow cylindrical basic shape, which is fastened to the front side on the printed circuit board 13. In the ring 18 is

Potting compound 19 is filled so that it covers the LED chips 17. The potting compound 19 has a transparent

 Matrix material, here: silicone, which is mixed with phosphor as filler. The LED chips 17 radiate purely by way of example blue (primary) light from, while the phosphor partially converts the blue primary light in its passage in yellow (secondary) light. At the front surface of the potting compound 19, which in

Hereinafter referred to as "light exit surface" 20, mixed blue-yellow or white mixed light occurs as

Useful light off. To achieve a desired (sum) color location of the mixed light as accurately as possible, is an accurate

Setting the layer thickness of the potting compound 19 above the LED chips 17 important. The adjustment of the thickness of

Potting compound 19 as well as its material properties such as hardness are thus dominated by the desire to achieve the color, not by the desire to achieve a good protective function. Thus, the silicone of the potting compound 19 is usually soft and sensitive to mechanical stress. The CoB area 12 in turn is circumferentially surrounded laterally by a dam 21 with a hollow cylindrical basic shape, namely with a gap through a (ring) gap 15. To the front of the dam 21 is on the potting compound 19 and their

Light exit surface 20 before. The dam 21 has a

Wall thickness or thickness in a range between one and ten millimeters. A height of the dam is preferably also between one and ten millimeters.

The dam 21 is filled with translucent, here: transparent, cover 22 to over the light exit surface 20. A layer thickness of the covering material 22 above the light exit surface 20 is in a range between one and ten millimeters. The cover material 22 is in particular moldable, so that it can easily penetrate into the gap 15 during filling into the interior of the dam 21 and thus the dam 21 can fix laterally against the CoB region 12. The cover material 22 is also selected here as silicone, but in a greater hardness after curing than the silicone of the potting compound 19. The cover material 22 thereby enables better protection of the CoB region 12, in particular with respect to an external mechanical stress.

The cover material 22 may consist of non-scattering silicone in order to achieve a particularly high light output. However, the cover material 22 may also have deliberately introduced scattering particles or scattering centers in a silicone matrix in order to increase a light homogeneity.

The use of the same base material or material type (here: silicone) both for the CoB proprietary potting compound 19 and for the covering material 22 has the advantage that

(if any) only a small material mismatch occurs and also a particularly good connectivity of both

Materials is made possible. A good connectivity is achieved in particular when the silicone of the

Covering material 22 is self-adhesive. Another advantage consists in an at least similar, in particular practically the same refractive index, whereby reflection losses can be kept low. The light-emitting module 11 further has a cover 24 which is attached peripherally to the printed circuit board 13 and which has a central circular light passage opening 25. The

Light transmission opening 25 is located on the front side in front of the light emission surface 20 of the CoB region 12, wherein an edge 26 of the light transmission opening 25 extends above a front side facing the cover 24 in the form of an annular end face 27 of the dam 21. In this case remains in the height of a small gap 28 between the front end face 27 of the Dam 21 and the lid 24. This allows a safe

Placing the lid 24 on the circuit board 13. The gap 28 can be sealed by placing a sealant 29 after placing the lid 24.

By this sealing a formed by the circuit board 13, the dam 21 and the lid 24 cavity 30 is sealed against the outside environment. In the area of

Cavity 30 and thus outside of the dam 21 13 and 13 electrical and / or electronic components 31 are arranged on the front side 16 of the circuit board. These may e.g. serve an electrical connection of the light-emitting module 11 (for example an electrical plug) or for operating the LED chips 17 (for example at least as part of a drive or

Driver electronics) may be provided. The electrical and / or electronic components 31 are electrically connected to the LED chips 17 via suitable conductor tracks (not shown).

Although the lighting device 11 is shown here with a cover material 22, the front, free surface 32 is flat, the lighting device 11 is not limited thereto. Thus, the free surface 32 may be e.g. at least partially nonplanar, e.g. be curved,

for example, be curved convex or concave.

2 shows a sectional side view of a lighting device 41 according to a second embodiment.

The lighting device 41 has a lower-side pad 42, on whose front side a CoB module 43 is fixed. The CoB module 43 has, similar to the light-emitting module 11 from FIG. 1, a CoB region 12 with a plate-shaped

Printed circuit board 13, e.g. from FR4, on. At the front 16 of the circuit board 13 are also several here

Semiconductor light source chips in the form of LED chips 17.

The LED chips 17 are also surrounded by a CoB own ring 18 having a hollow cylindrical basic shape, which is fixed on the front side of the circuit board 13. In the ring 18 is Potting compound 19 is filled so that it covers the LED chips 17. The potting compound 19 also has one here

transparent matrix material made of silicone, which with

Phosphor as filler is added. At the

Light exit surface 20 then also emerges mixed light as useful light.

The CoB module 43 is circumferentially surrounded by a dam 44 with a hollow cylindrical basic shape, namely gap-shaped to the circuit board 13 through a gap 45. To the front of the dam 44 is on the potting compound 19 and their

Light exit surface 20 of the CoB module 43 before. A height of the dam 44 is preferably between one and ten millimeters, plus the height of the printed circuit board 13. The dam 44 is covered with transparent cover material 22 to above

 Light exit surface 20 filled. A layer thickness of

Covering material 22 above the light exit surface 20 is also in a range between one and ten

Millimeters. The cover material 22 is also chosen here as a comparatively hard silicone.

In contrast to FIG. 1, the covering material 22 now also covers the remaining printed circuit board 13 and thus also protects the functional elements arranged thereon, such as printed conductors, electrical and / or electronic components 31, etc. Since silicone is inexpensive, the use of a larger material volume increases it the cost of the lighting device 41 is not essential. On a cover may now be dispensed with. Although the invention is shown in detail by the

 Embodiments have been further illustrated and described, the invention is not limited thereto and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

So the cover material quite generally as an alternative to

Streupartikeln other filling material have. So may the cover material in general also have phosphor. Generally, "on", "an", etc. may be taken to mean a singular or a plurality, in particular in the sense of "at least one" or "one or more", etc., as long as this is not explicitly excluded, eg by the expression "exactly a "etc.

Also, a number may include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

Reference sign

11 light module

 12 CoB range

 13 circuit board

 15 gap

 16 front of the circuit board

 17 LED chip

 18 CoB own ring

 19 potting compound of the CoB area

 20 light exit surface

 21 dam

 22 cover material

 24 lids

 25 light aperture of the lid

 26 edge of the light passage opening

 27 annular end face of the dam

 28 gap between dam and lid

 29 sealant

 30 cavity

 31 electrical and / or electronic component

32 free surface of the cover material

 41 Lighting device

 42 base

 43 CoB module

 44 dam

 45 gap

Claims

Lighting device (11; 41),  - Having at least one CoB area (12) with  at least one semiconductor light source chip (17) applied to a printed circuit board (13), - Wherein the at least one semiconductor light source chip (17) by means of a CoB own translucent potting compound (19) is covered  - and the CoB's own translucent potting compound  (19) is covered at its light emitting surface (20) by a translucent covering material (22) cast thereon. Lighting device (11; 41) according to one of the preceding claims, wherein  - The CoB region (12) is laterally surrounded by a dam (21; 44) which projects beyond the CoB region (12), wherein  the covering material (22) in the dam (21, 44)  is filled. Lighting device (11) according to one of the preceding claims, wherein the dam (21) on the circuit board (13) is placed. A lighting device (11) according to claim 3, wherein the dam surrounds the CoB region (12) laterally slit. Lighting device (11; 41) according to one of the preceding claims, wherein the cover material (22) has a greater hardness than the CoB's own translucent potting compound (19). 6. A lighting device (11; 41) according to claim 5, wherein the covering material (22) has a Shore A hardness of at least 60, in particular of at least 70, having. 7. Lighting device (11; 41) according to one of the preceding claims, wherein  the lighting device (11; 41) has a cover (24) with a light passage opening (25),  - Which light passage opening (25) before the  Light emitting surface (20) of the CoB region (12) is located and wherein  - An edge (26) of the light passage opening (25) above a lid (24) facing the front side (27) of the dam (21, 44) extends. 8. lighting device (11; 41) according to any one of the preceding claims, wherein the cover material (22) comprises transparent material. A lighting device (11; 41) according to claim 8, wherein said cover material (22) is a transparent base material  in which scattering particles are distributed as filling material. 10. Lighting device (11; 41) according to one of the preceding claims, wherein the covering material (22) comprises heat and blue light-stable material. 11. Lighting device (11; 41) according to one of the preceding claims, wherein the covering material (22) comprises self-adhesive silicone. 12. Lighting device according to one of the preceding  Claims wherein the cover material (22) is polyacrylic Polyurethane copolymer has. 13. Lighting device (11; 41) according to one of the preceding claims, wherein the cover material (22) a  Layer thickness between one and ten millimeters having . 14. Lighting device (11; 41) according to one of the preceding claims, wherein the covering material (22) has an at least partially curved free surface (32). A lighting device (11; 41) according to any one of the preceding claims, wherein the dam (21; 44) has a wall thickness of between one and ten millimeters.