Optoelectronic device

0001The invention relates to an optoelectronic component, in which an optoelectronic chip by means of a well heat-conductive bonding agent on a chip carrier part a leadframe (leadframe) is fixed, the lead frame one arranged in a distance from the chip carrier part, electrically conductive with an electrical contact of the chip associated connection part, and wherein the chip and at least one partial region of the chip carrier part and of the connection part are surrounded by a sheath, in such a way that for a certain PCB, the lead frame provided external terminals of the chip carrier part and the protrude connecting part of the enclosure or completely lie outside the envelope. It refers in particular on an optoelectronic component having an optoelectronic Semiconductor chip, in particular at a high power-driven light-emitting diode chip (LED).

0002Such a component is, for example, from the European Patent application EP 400 176 known. Herein is a so-called TOPLEDs described in which a light emitting Semiconductor chip (LED chip) on a flat part of a chip carrier Lead frame is attached. The leadframe is made composed of the chip carrier part and a to a distance This, therefore electrically insulated from this arranged connector each with an external terminal. The chip carrier part with the semiconductor chip, the connecting part and Portions of the external terminals by a casing surrounded, the radiopaque of a base body filling with a recess and a recess these radiation transmissive window part consists. The chip carrier part and the connection part are such from the base body surrounded or embedded in this, that portions of the Upper sides of the chip carrier part and of the connection part with the remaining bottom surface of the recess flush. The semiconductor chip is down to its bottom, it with the rests on the chip carrier part, fully transparent to radiation from the surrounded part of the window. The recess and the inner surfaces thereof are shaped and arranged such that they a in for the radiation emitted by the semiconductor chip radiation Substantially frustoconical reflector forms.

0003In DE 19536454A1 is an optoelectronic component described in which, to improve heat dissipation from the Semiconductor chip two external terminals of the chip carrier part the leadframe opposite the external terminals of the connecting part are widened.

0004In the above described known optoelectronic devices occurs in operation of the semiconductor chips at high Currents and thus at high power, as for example, in so-called power LEDs is the case due to insufficient Heat dissipation from the semiconductor chip to its strong Heating. This heating often leads to impairment the operability of the semiconductor chip, such. B. accelerated aging, cancel the semiconductor chip from Lead frame, cancel the bond wires or destruction of Crisps. The known widened external ports The chip carrier part promote delamination of the plastic from the lead frame, the z. B. penetration of moisture may cause the semiconductor chip.

0005The invention is therefore based on the object, the optoelectronic Component of the aforementioned type such that ensures improved heat dissipation from the chip is, without at the same time the housing dimensions essential and without changing at the same time the risk of delamination to substantially increase.

0006This object is achieved by a device with the features of Claim 1.

0007Advantageous developments of the components of the invention are the subject matter of the subclaims.

0008In the device according to the invention it is provided that the Chip carrier part at least three separate, with the chip carrier part having thermally conductively connected external terminals, which having at different, spaced apart protrude points of the envelope from this and which are shaped such that it in on a mounting for the the component provided PCB mounted state the device all at once on the terminal or PCB rest. The operation of the device in the chip resulting heat is hence at three different points fed into the circuit board and a large area of ​​this distributed. Thereby, a clearly improved heat dissipation achieved by the optoelectronic chip.

0009In a particularly preferred embodiment of the invention Component extend the external terminals seen of the chip carrier part in plan view of the lead frame, starting separated from the chip carrier part from one another in the Essentially star-shaped outwardly. The heat dissipation points from the component to the PCB out thereby exhibit relatively large distances from each other, whereby a very large-scale distribution of the operation of the component on the chip carrier part and its external connections from Chip derived thermal energy to the circuit board is achieved.

0010Advantageously, the external terminals in the area, in which they extend in a star shape outward longitudinal center axes , of which respectively two mutually adjacent enclose an angle of about 90 °. With this arrangement, is the plastic range between the terminals maximum, whereby the risk of delamination z. B. with temperature variations is reduced.

0011Is a component having at least a first and a second optoelectronic chip provided so has inventively the chip carrier part at least two external connections on which one another at various spaced having points of the envelope of these protrude. The lead frame here has at least two connecting parts each with an external terminal, which also laterally protrude from the enclosure. Preference is also given here are the external terminals of the chip carrier part and the connecting parts seen in plan view of the lead frame in the Substantially arranged in a star shape, thereby providing maximum Distance of the external terminals of the chip carrier part of each other is guaranteed. The operation of the device in about the chip carrier part and its external connections from the chip derived thermal energy is characterized by relatively spaced points in the printed circuit board fed, so that once again a very good heat distribution is achieved on the circuit board.

0012Particular preference is given in the latter component the external terminals of the chip carrier part in plan view Seen on the lead frame with respect to the chip carrier part diagonally staggered. They project to another opposite side surfaces of a preferably Essentially cuboid envelope out of it. The Connection parts are in this case on different sides of arranged the chip carrier part and extend its external connections also on opposite side surfaces the envelope out of it. In plan view of the lead frame they are with respect to the chip carrier part to the external opposite terminals of the chip carrier part to each other diagonally staggered.

0013To improve heat transfer away from the chips, if necessary, further to improve the chip carrier part can also be more than two external have connections, which in turn at different a Distance from each other having points of the envelope protrude therefrom. The number of external connections can as required depending on the allowable size of the component be further increased.

0014In an inventive device, the so-to a printed circuit board can be secured so that in operation thereof the the radiation emitted by the chip substantially parallel is radiated to the PCB (laterally emitting Component), the chip carrier part at least two external Connections and the connection part at least one external Port on which separated at one and the same Side surface of the envelope of these protrude. The external Connection of the connection part is in this case preferably between the two external terminals of the chip carrier part arranged.

0015In a particularly preferred development of the latter Device is the external terminal of the connection part narrower than the two external terminals of the chip carrier part. Of course, optionally also at the other components above invention, the external Terminals of the chip carrier part to be wider than the external terminals of the connector parts.

0016In a further development of the above-mentioned side emitting Component of the chip carrier part is additionally provided with at least a cooling vane thermally connected, on a other side surface of the enclosure as the terminal parts of these projects. This cooling vane alone or to this Cooling vane thermally connected additional cooling device ensures a further improved heat dissipation from Chip.

0017Further advantages and preferred embodiments up from the below in connection with Figures 1 3b closer embodiments explained. Show it:<sl><li>Figure 1a is a schematic representation of a plan view of a Embodiment of an inventive device with a single optoelectronic chip,</li><li>Figure 1b is a schematic representation of a section through the embodiment of Figure 1 along the line AA, Figure 2 is a schematic representation of a plan view of a Embodiment of an inventive device with at least two optoelectronic chips,</li><li>3a shows a schematic representation of a side view an embodiment of an inventive laterally emitting device and</li><li>Figure 3b is a schematic representation of a section through the embodiment of Figure 3 along the in Figure 3 drawn line AA.</li></sl>

0018In the figures, identical and functionally identical components the various embodiments always the same Reference numerals.

0019In the device according to Figure 1 is a Light-emitting component, in which on a chip carrier part 2 a leadframe (leadframe) 7 a light-emitting Semiconductor chip 1 (LED chip) by means of a good heat conductor Connecting means, eg. As by means of a metallic solder is attached. Three separate external terminals 4, 5, 6 extend starting from the chip carrier part 2 in three different Outward directions. In a distance from the chip carrier part 2 with the external terminals 4, 5, 6 is a connecting part 8 arranged with an external terminal 9, the by a bonding wire 16 to an electrical contact of the LED chip 1, z. B. connected to the Anodenkontaktierung is. A second contact metallization (cathode contact) the LED chip 1 is, for example, at its the chip carrier part 2 facing bottom and is connected to the Chip carrier part 2 by means of the in this case also electrically conductive connecting means electrically connected. Of the Chip carrier part 2 to the external terminals 4, 5, 6 is used Consequently, in this case both as a cathode terminal and as a thermal connection for heat dissipation from the LED chip.

0020If the cathode contact not mentioned as in the above Case, arranged on the underside of the chip 1, but z. B. on its upper side, this can by a bonding wire with be the chip carrier part 2 electrically connected.

0021The chip carrier portion 2, the connecting part 8 and portions of their external terminals 4, 5, 6, 9 are in a Essentially cuboid base 10 of casing 3 enclosed, which has a recess eleventh recess 11 has substantially the shape of a truncated cone and ranging from a plane parallel to the lead frame 7 major surface 17 of the base 10 to the lead frame 7, wherein the cross section of the recess 11 from the lead frame 7 to the Major surface 17 of the base 10 toward increased. The LED chip 1 is located in the recess 11, with a radiation-permeable window part 22, preferably with a transparent plastic cast is provided. This part of the window 22 forms together with the base body 10 an envelope 3 of the device. The external terminals 4, 5, 6, 9 protrude on opposite side faces 18,19 of the Base 10 out of this. They run inside of the base body 10 starting from the chip carrier part 2 is first essentially star-shaped apart and bend in Later on, such that they, the side faces 18,19 penetrate vertically.

0022The chip carrier part 2 is preferably entirely within the bottom surface of the recess eleventh

0023The external terminals 4,5,6,9 point in the range in which they extend in a star shape outward longitudinal center axes 23,24,25, of which respectively two mutually adjacent enclose an angle of about 90 °.

0024The external terminals 4, 5, 6, 9 are outside the body 10 opposite to the first major surface 17 of the first second major surface 20 of the base 10 toward and in the course below the base body 10 to its Towards the middle bent. They can also, as shown in Figure 1b indicated by dashed lines to swing shaped connection stubs be bent. This, too, represents a per se in Surface Mount Technology common form of external electrical Connections. These types of external terminals for surface mount devices (SMD) are known per se and no further explanation therefore at this point.

0025The external terminals are thus formed such that they in on a provided for the mounting of the component PCB mounted state of the device all at once rest on the supply or circuit board.

0026The inner surfaces of the recess 11 form a reflector for the light emitted from the LED chip 1 in the operation of the component Radiation. They are optionally available with a reflection-enhancing Material coated. Alternatively, the base body of a reflection-enhancing material.

0027In the embodiment of Figure 2, in contrast the embodiment of Figures 1a and 1b on a chip carrier part 2 of a lead frame 7 of two different colors luminous LED chips 1, 13 by means of a thermally and electrically conductive connecting means secured. on opposite Sides of the chip carrier part 2 are at a distance arranged on this, a first 8 and a second connection part 12, each of which has an external connection 9.14. These external terminals 9.14 parallel offset each other, extend, seen from the chip carrier part 2, in mutually opposite directions and extend to opposed side surfaces 18,19 of the base body 10 out of this. They are means of bonding wires 16 with the anode contacts of the LED chips electrically 1.13 conductively connected.

0028The chip carrier part 2 has two external terminals 4.5, which, starting from the chip carrier part 2 essentially also parallel offset from one another in mutually opposite Directions parallel to the external terminals 9,14 the connecting parts extend 8.12 and opposite to each other Side surfaces 18,19 of the base 10 of this protrude.

0029As in the embodiment of Figures 1a and 1b, has the radiopaque base body 10 a frustoconical Recess 11, which with a transparent window part 22 is provided. The LED chips are 1.13 in this recess eleventh

0030The external terminals 4,5,9,14 protrude on opposite Side surfaces 18,19 of the base 10 of this out. They are analogous to the outside of the base 10 Embodiment formed according to Figures 1a and 1b.

0031In the embodiments described above are each the sheath 3 and the external terminals such 4,5,6,9,14 formed that, in operation of the device by the or by the LED chip / s radiation emitted substantially perpendicular for mounting a surface for the mounting of the component provided circuit board is radiated.

0032In the embodiment of figure 3a and 3b is is. a so-called side-emitting LED device This type of device is generally part the description explained. The casing 3 and the external terminals 4,5 and 9 of the chip carrier part 2 and the Terminal portion 8 are formed in this component, that with a side surface 20 of the body 10 attached attention to this to the mounting surface of a circuit board can be.

0033For this purpose, a lead frame 7 a chip carrier part 2, the at least two external connections has 4.5. These external Connections 4.5 extend initially starting from Chip carrier part 2 on which an LED chip 1 by means of a thermally mounted and electrically conductive connecting means is, in substantially opposite directions to the outside. In the further course they bend from the same direction, so that they then parallel to each other in the same Direction run. Between the two external terminals 4.5 of the chip carrier part 2 is a connector 8 with a external terminal 9 are arranged in parallel to the two external terminals 4.5 of the chip carrier part in the same Direction as it passes.

0034The chip carrier part 2, whose external connections 4.5, the terminal part 8 and its external terminal 9 are analogous to the two embodiments described above, with a radiopaque base body 10 enclosed a truncated cone-shaped recess 11, into which the LED chip 1 is arranged. The recess 11 is also here with a radiation-transmissive window part 22 is provided, the preferably consists of a radiation-permeable plastic. The external terminals 4,5,9 protrude on one and the same Side surface 18 of the base 10 of this out, are outside of the base 10 downward toward Back of the base body is bent 10 and are further Extending along the rear side 21 of the base body 10 to its Towards the middle bent. The from the side surface 18 of the base body 10 facing away from outer surfaces of the external terminals 4,5,9 form a bearing surface of the component to which Mounting on a circuit board.

0035For additional cooling of the LED chip 1, the chip carrier part 2 with a cooling tab 15 (except in Figures 3a and 3b shown in phantom). This extends to one of the Side surface 18 from which the external terminals protrude 4,5,9, opposing side face 19 of the base body 10 out of this and is outside of the main body 10 to whose rear side 21 bent toward such that they on the Side face 19 rests. At this cooling tab 15 can optionally additional cooling devices are thermally connected.

0036In all the embodiments described above are preferred the external terminals of the chip carrier part 2 wide as the external ports and the connecting parts 8.12. Thus, when substantially unchanged Housing dimensions a further improved heat dissipation from the LED chip 1 can be obtained. The external terminals can 4,5,6,9,12 but all have the same width.

0037In order to further improve the heat transported away from the LED chip achieve, are on one of the mounting of the component provided PCB particularly large solder pads provided. These are also arranged in a star shape and can so the dissipated from the LED chip heat over a large area on the distribute printed circuit board. The leadframe of the invention Components lead the star-shaped heat from the LED chip to the outside of the enclosure. This causes the heat to far apart distant points fed to the board. On The board has a preference to each solder pad large, for example made of copper metallizations distribute the heat on the circuit board. The thermal resistance the housing according to the invention is compared to the thermal resistance conventional LED package significantly reduced.

0038In the above described housings for LED chips are to optoelectronic order known in semiconductor technology for housing Components. The particular forms that this Materials and manufacturing used are therefore at this point no longer explained in detail.

0039The description of the invention based on the embodiments is not self-evident as limiting the invention to be understood to these examples.