DE102010001791A1 - LED-assembly, has light emission opening unsealed by enclosing unit, and electro static discharging units formed in such manner such that discharging units made up of ceramic material form enclosing unit - Google Patents

Abstract

The assembly has electrical supply units supplying power to an LED-chip, and an enclosing unit (4) partially surrounding the LED-chip. A light emission opening (10) is unsealed by the enclosing unit, and electro static discharging units (7, 8) are formed in such a manner that the discharging units made up of ceramic material form the enclosing unit. The LED-chip is arranged on a substrate layer that is made up of electrical non-conducting material selected from aluminum nitrate or aluminum-di-oxide, and the discharging units are made up of the ceramic material.

Description

The invention relates to an LED assembly
with at least one LED chip,
with electrical supply means for powering the LED chip (s),
encasing means for the LED chip (s) surrounding the LED chip (s) at least partially framed and having an exit port for the light; and ESD means for protecting the LED chip (s) against overvoltage damage ,

Of the Term LED stands for the English term "light emitting diode "(light-emitting diode). The term ESD stands for the English term "electrostatic discharge" (electrostatic discharge) Discharge).

An LED assembly of the aforementioned type is for example according to US 2008/0142831 A1 known. This has two printed circuit boards. On the one circuit board, an LED chip is arranged. On the other circuit board is an unspecified described element, which serves to protect the LED chip against overvoltage. For this purpose, the element is connected in parallel to the LED chip. If overvoltages occur at the voltage supply connections for the LED chip, the element becomes low-resistance. The two circuit boards are encapsulated in a package of insulating material. The package has a light exit opening through which the LED chip can radiate the light generated by it. This means that the package surrounds the LED chip like a frame. On the outside of the package are two supply connections, which are electrically connected to the two printed circuit boards. The LED chip can be supplied with power via these supply connections.

US 2008/0 25 449 A1 shows a component for overvoltage protection by means of a varistor layer, which is located on a ceramic substrate. Within a bulge of the varistor layer, an LED chip is arranged. This is located on a heat conductor that extends vertically through the ceramic substrate. The LED chip is electrically connected via two terminals having via holes having a silver fill, each terminal being electrically connected to a layer of the varistor layer. It is proposed a flip-chip mounting of the LED chip, and advised against an electrical connection by means of bonding wires, since these can lead to shading effects. The component is additionally covered on top by a glass-ceramic layer.

EP 1 858 033 A1 also discloses a varistor component in which a varistor is mounted on a ceramic substrate and has a recess in which an LED chip is disposed. The ceramic substrate consists of an aluminum substrate with a purity of 96%. The ceramic substrate is thus used for heat dissipation. The ceramic substrate may mainly contain one of the materials aluminum oxide, zirconium oxide, silicon oxide or magnesium oxide. The varistor component is additionally covered on top by a glass-ceramic layer.

US 2008/0 224 815 A1 as filed by the same applicant US 2008/0 25 449 A1 , represents a modification of the component shown there US 2008/0 224 815 A1 claimed embodiment, additional terminal electrodes are mounted on the glass-ceramic layer, which are electrically connected to the via holes. An electrical connection to the LED chip is now realized by two metal wires are each attached to a terminal electrode and the top of the LED chip. The metal wires protrude beyond the component.

Farther is a LED package on the market, which is distributed by the company Lumileds "Rebel". This LED package has a substrate of ceramic material, on which an LED chip is arranged. On top of the substrate run traces that are connected to the corresponding traces on the Bottom of the substrate via contacting holes are electrically connected. The LED chip can handle this way Be supplied with electricity. Next to the LED chip is on the substrate continue a TVS element connected in parallel to the LED chip and this is to protect against surges. The abbreviation TVS stands for the English term "transiant voltage suppressor ". The TVS element thus has the function of initially described ESD means. The LED chip and the TVS element are covered by a silicone lens.

To mention is also a product on the market the company Nichia, sold under the name "Rigel" becomes. In this case, the containment means of a SMD component designed ceramic package formed with a light exit opening forming central recess is provided at the bottom of a LED chip is arranged. The abbreviation SMD stands for the English term "surface mounted device". The LED chip is going over to the outside Power supply lines. The protection of the LED chip against a Damage caused by overvoltages is used here Zener diode in the form of a separate component.

Based on the above-described known LED assembly, the invention has for its object to simplify this constructive so They can be made easier and cheaper using modern manufacturing methods.

The The object is achieved according to the invention that the ESD funds are shaped so that they include the containment form.

Conveniently, the LED chip (s) on a substrate layer will not become electrically conductive arranged conductive material, as with the well-known LED assembly "Rebel" of Lumileds is the case.

For the practical embodiment of the solution according to the invention, it is proposed that the ESD means be arranged on the substrate layer and formed by at least one ESD layer and at least two electrically conductive electrode layers, wherein the / each ESD layer is embedded between each two electrode layers, of which one each connected to one of the two power supply terminals of the / an LED chip,
and that the ohmic resistance of the / each ESD layer is voltage-dependent, such that it decreases with increasing voltage to the electrode layers enclosing the relevant ESD layer and increases with decreasing voltage.

Especially then, if the LED package has multiple LED chips, should the frame expediently a plurality of have as packet over arranged ESD layers, each ESD layer being between two of a corresponding one Embedded variety of electrically conductive electrode layers is.

Aluminum nitride (AlN) is preferably used as the material for the substrate layer because, despite its excellent electrical insulating properties, it is a very good conductor of heat. This makes it possible to dissipate the heat generated in the LED chip (s). Advantageously, the use of a substrate layer of aluminum nitride (AlN) also simplifies the structure as a whole since no additional heat conductor is required, as is required, for example, in US Pat US 2008/0 25 449 A1 is shown. Alternatively, aluminum dioxide (Al ₂ O ₃ ) is also suitable for the substrate layer. The latter material is characterized in that it reflects well the light generated by the LED chip (s).

Also For the ESD layer (s) one preferably uses ceramic material. This gives the possibility for the production the LED assembly to apply the LTCC technology. The abbreviation LTCC stands for the English term "low temperature cofired ceramics "(low-temperature sintering technology).

Another expedient refinement may be that conductor tracks in the form of a solder layer are applied to the underside of the substrate layer,
the substrate layer is provided with via holes,
in that a conductor layer-forming conductor layer is arranged between the substrate layer and the LED chip (s),
in that the conductor tracks of the conductor layer are electrically connected to the corresponding conductor tracks on the underside of the substrate layer via the via holes, and that the electrodes of the LED chip (s) are electrically connected to the corresponding conductor tracks on the upper side of the substrate layer.

The Electrode layers are expediently with the corresponding conductor tracks at the top of the substrate layer electrically connected.

In order to protect the LED chip (s) and to reflect the light emitted by this / these as well as possible, a cover frame part of aluminum (Al) or aluminum dioxide (Al ₂ O ₃ ) can be placed on top of the frame.

One Another proposal to simplify the production of the LED assembly there is also the possibility that the / the LED chip / s designed as a COB component / e and by COB technology also the Conductor tracks located on the top of the substrate layer Conductor layer is / are applied.

One Embodiment of the invention will be described below of the drawings.

It demonstrate:

1 an oblique view from above of a perspective view of a substrate plate with a conductor layer and four LED chips;

2 a view obliquely from above on the substrate layer in 1 aufzusetzenden frame with light passage opening;

3 a view obliquely from above on a perspective view of the assembled assembly;

4 a view obliquely from above on the 180 degrees turned assembly from 3 ;

5 an exploded view of in 3 shown assembly in perspective view, but after a 90 degree rotation about an imaginary vertical axis;

6 a view VI 5 on the ESD layers and the electrode layers after they have been assembled.

1 shows a substrate plate 2 of an electrically insulating material such as a ceramic material, preferably one of aluminum nitride (AlN) or aluminum dioxide (Al2O3), on top of which an electrically conductive layer 6 is applied, made of conductor tracks 6a - 6f consists. On the extended sections of the tracks 6a - 6d are four LED chips 3a - 3d Applied by COB technology. COB stands for the English term chip on board. Each of the LED chips 3a - 3d is provided with two connection contacts, one of which is located on its underside and with the corresponding conductor track 6a - 6d soldered or glued. The other terminal contact is located on top of the LED chip and through the respective wires 11a - 11d with the corresponding trace 6e . 6b . 6c and 6f connected. This ensures that two of the four LED chips are connected in series, in this case the LED chips 3a and 3b one hand, and the LED chips 3c and 3d on the other hand. Of course, circuits are also possible in which the LED chips are driven individually or in other combinations when the corresponding contacts are made to the underside of the unit.

In the tracks 6a - 6d open through holes 12 passing through the substrate plate 2 passed through.

The on the substrate plate 2 in 1 to be set up 4 is in 2 shown. It consists of a plurality of stacked ESD layers as a packet 8th and interposed electrode layers 7 whose exact arrangement and positioning later still in conjunction with 5 is explained. The frame 4 is up with a deck frame part 9 made of aluminum (Al), glass or aluminum dioxide (Al2O3). In the middle, the frame points 4 a light passage opening 10 on top of that by the LED chips 3a - 3d generated light can be emitted. The frame 4 with the top-mounted deck frame part 9 has a double function. On the one hand, it serves the LED chips 3a - 3d to protect against mechanical damage; On the other hand, it also protects the LED chips against damage caused by surges. The latter function will be explained later in more detail.

3 shows the assembled unit 1 , where it can be seen how the LED chips safely against mechanical damage in the opening of the frame 4 are embedded. In the production state according to 3 The LED chips are connected by two connecting wires 11 connected to the corresponding tracks, namely the LED chip 3a with the conductor track 6e , the LED chip 3b with the conductor track 6b , the LED chip 3c with the conductor track 6c and the LED chip 3d with conductor track 6f (please refer 1 ). There are therefore two connecting wires 11 used because they can be correspondingly thinner and thus more flexible than just one. Thus, shading effects such as silhouette formation by the bonding wires can also be reduced. Also, the uniformity of the light emission is less affected. Of course it is also possible, only one connecting wire 11 to use. This possibility is in 5 shown. Advantageously, the wires do not protrude out of the LED package but are from the deck frame part 9 not only laterally surrounded and thus protected laterally but also projects in a vertical orientation. Thus, the deck frame part 9 This protection is accordingly ensured already in an early production phase of the LED assembly, for example, before the LED assembly is inserted into a lamp, or before the frame part 9 is filled with a transparent potting compound or before a transparent cover on the frame part 9 is put on.

4 shows the LED assembly 1 from underneath. One recognizes that also the underside conductor tracks 5a - 5e which of a solderable layer 5 are formed. The four track islands 5a - 5d are with via holes 12 through the substrate plate 2 to the tracks 6a - 6d at the top of the substrate plate 2 electrically connected. It should be noted that the 1 and 2 on the one hand and the 3 and 4 on the other hand rotated against each other in a vertical axis by 90 degrees.

5 shows an exploded view of the LED assembly 1 out 3 , One recognizes the substrate plate 2 with the via holes 12 , Above the substrate plate 2 is the conductor layer 6 with the tracks 6a - 6f , On the to the tracks 6a - 6d belonging conductor track surfaces sit the LED chips 3a - 3d , About the LED chips 3a - 3d a stack of 2 x 4 stacked electrode layers is shown. The right stack is from the electrode layers 7a - 7d educated. The left stack is from the electrode layers 7e - 7h educated. The two stacks are not electrically connected. They are over the via holes 12 with the tracks 5a - 5e at the bottom of the substrate plate 2 located solder layer 5 connected.

In this regard, it should be noted that the pattern of the tracks 5a - 5e on the bottom the substrate plate 2 not exactly with the pattern of the tracks 5a - 5e in 4 matches. However, this is of minor importance for the function of the LED assembly. As well in 4 as well as in 5 has the solder layer 5 at the bottom of the substrate plate 2 5 tracks each 5a - 5e ,

Over the two stacks of electrode layers 7a - 7d and 7e - 7h There is a stack of 5 ESD layers 8a - 8e , which are not duplicated as the electrode layers 7 ,

At the top, the conclusion forms the already mentioned Deckrahmenteil 9 ,

5 shows the electrode layers 7 and the ESD layers 8th in an exploded form. Like the electrode layers 7 and the ESD layers 8th actually arranged, shows 6 , It can be seen that between every two electrode layers 7 one ESD layer each 8th is arranged. Each one ESD layer 8th enclosing electrode layers have a different potential. In this specific case is due to the via via holes 12 supplied opposite polarity electrode layers, the voltage which is supplied in each case two series-connected LED chips. In case of 6 Make the right stack with the electrode layers 7a - 7d shows, on each of the ESD layers, the voltage applied to the series connected LED chips 3c and 3d is supplied. Of course, there are also other connection options for the ESD layers.

The electrode layers 7a - 7d are formed by two electrode layers groups each having at least two superimposed and electrically connected electrode layers 7a . 7c and 7b . 7c educated. Advantageously, the electrode layers of a group may also be mechanically interconnected so as to form a solid unit. The electrode layers 7a . 7c and 7b . 7c are interlocked by being telescoped during production of the LED package. However, there is basically an ESD layer between two electrode layers. By means of the ESD layers 7a - 7d Thus, an electrical insulation of the two groups is guaranteed from each other. The two groups may thus have a different electrical potential, that of the different terminals described above via the via holes 12 results.

The arrangement described in the paragraph above also applies to the second stack of electrode layers 7e - 7h Application.

The ESD layers 7a - 7h are made of an electrically nonconductive material, preferably a ceramic material, whose ohmic resistance decreases when at the adjacent electrode layers 7 applied voltage increases and vice versa. In this way, the desired protection of the LED chips 3a - 3d realized against damage due to overvoltages.

By using ceramic material having the properties described above, it is possible to use the LED component 1 Using modern manufacturing methods, such as the LTCC technology and the SMD technology cost-effective and compact manufacture.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2008/0142831 A1 [0003]
• US 2008/025449 A1 [0004, 0006, 0014]
• EP 1858033 A1 [0005]
• US 2008/0224815 A1 [0006, 0006]

Claims (15)

LED assembly ( 1 ) with at least one LED chip ( 3 ), with electrical supply means ( 5 . 12 . 6 ) to power the LED chip (s) ( 3 ), with containment means ( 4 ) for the LED chip (s) ( 3 ) containing the LED chip (s) ( 3 ) at least partially surrounded by a frame and a light exit opening ( 10 ) and with ESD funds ( 7 . 8th ) for protecting the LED chip (s) ( 3 ) against damage by overvoltage, characterized in that the ESD means ( 7 . 8th ) are shaped so that they also contain the containment means ( 4 ) form. LED assembly ( 1 ) according to claim 1, characterized in that the LED chip (s) (s) ( 3 ) on a substrate layer ( 2 ) is arranged from electrically non-conductive material / are. LED assembly ( 1 ) according to claim 2, characterized in that the ESD means ( 7 . 8th ) on the substrate layer ( 2 ) and at least one ESD layer ( 8a - 8e ) and at least two electrically conductive electrode layers ( 7a - 7h ), wherein the / each ESD layer ( 8a - 8e ) between each two electrode layers ( 7a - 7h ), of which one each with one of the two power supply terminals of the / an LED chip ( 3 ) and that the ohmic resistance of the / each ESD layer ( 8a - 8e ) is voltage-dependent, such that it is connected to the ESD layer ( 8a - 8e ) including electrode layers ( 7a - 7h ) decreases and increases with decreasing voltage. LED assembly ( 1 ) according to claim 3, characterized in that the frame ( 4 ) a plurality of stacked ESD layers ( 8a - 8e each ESD layer between each two of a corresponding plurality of electrically conductive electrode layers ( 7a - 7d ) is embedded. LED assembly ( 1 ) according to the preceding claim, characterized in that the plurality of electrode layers ( 7a - 7d ) by two electrode layer groups each having at least two superimposed and electrically connected electrode layers ( 7a . 7c and 7b . 7c ) are formed, wherein the electrode-layer groups are interlocked and by means of the ESD layers ( 7a - 7d ) are isolated from each other. LED assembly ( 1 ) according to any one of claims 2-4, characterized in that the electrode layers comprise two electrically isolated stacks ( 7a - 7d . 7e - 7h ), which are arranged side by side. LED assembly ( 1 ) according to one of claims 2 to 6, characterized in that the substrate layer consists of aluminum nitride (AlN) or aluminum dioxide (Al2O3). LED assembly ( 1 ) according to any one of claims 3-7, characterized in that the ESD layer (s) ( 8th ) are made of ceramic material. LED assembly ( 1 ) according to any one of claims 2-8, characterized in that on the underside of the substrate layer ( 2 ) Conductor tracks ( 5a - 5d ) in the form of a solder layer ( 5 ) are applied, that the substrate layer ( 2 ) with via holes ( 12 ), that between the substrate layer ( 2 ) and the LED chip (s) ( 3 ) a conductor tracks ( 6a - 6f ) forming conductor layer ( 6 ) is arranged, that the conductor tracks ( 6a - 6f ) of the conductor layer ( 6 ) with the corresponding tracks ( 5a - 5d ) at the bottom of the substrate layer ( 2 ) via the via holes ( 12 ) and that the electrodes of the LED chip (s) ( 3 ) with the corresponding tracks ( 6a - 6f ) of the conductor layer ( 6 ) on top of the substrate layer ( 2 ) are electrically connected. LED assembly ( 1 ) according to any one of claims 2-9, characterized in that the electrode layers ( 7a - 7d ) with the corresponding tracks ( 6a - 6d ) at the top of the substrate layer ( 2 ) are electrically connected. LED assembly ( 1 ) according to one of the preceding claims, characterized in that the frame ( 4 ) a top of this seated deck frame part ( 9 ) made of aluminum (Al), glass or aluminum oxide (Al2O3). LED assembly ( 1 ) according to any one of claims 3-11, characterized in that the ESD layers ( 8a - 8e ) the electrode layers ( 7a - 7d ) and possibly also the cover frame ( 9 ) are manufactured and assembled by LTCC technology. LED assembly ( 1 ) according to any one of claims 2-12, characterized in that the LED chip (s) (s) ( 3 ) formed as a COB component / e and by COB technology on the interconnects ( 6a - 6f ) on the top of the substrate layer ( 2 ) conductor layer ( 6 ) is / are applied. LED assembly ( 1 ) after one of vorge herenden claims, characterized in that the / the LED chip / s ( 3 ) with wires ( 11a - 11d ) with the conductor track ( 6a - 6f ) are connected to the electrical contact. LED assembly ( 1 ) according to claims 11 and 14, characterized in that the wires ( 11a - 11d ) of the deck frame part ( 9 ) are projected in a vertical extension.