DE102007004807A1 - LED for use in electronic printed circuit board, has stand connected integrally with lens and extending in direction, which exhibits direction portion, which is aligned in direction of semiconductor chip - Google Patents

Abstract

The LED has a reflector (11), where a semiconductor chip, which is suitable for transmitting light, is fastened relative to the reflector. A lens (10) is suitable for conducting the transmitted light from the semiconductor chip during operation. A casting compound (12) is arranged between the semiconductor chip and the lens. A stand (103,104,105,106) is connected integrally with the lens and extends in a direction, which exhibits a direction portion, which is aligned in a direction of the semiconductor chip.

Description

The The invention relates to a light-emitting device in which a suitable for emitting light semiconductor device relative to a support element is attached. An optical body does that emitted by the semiconductor device light.

Background of the invention

conventional Light-emitting devices (LED) have a semiconductor chip, in the corresponding semiconductor structures are realized, the light when applying a supply voltage can send out. The emitted light includes radiation that is visible both in the visible Spectrum as well as in the non-visible spectrum can be. Of the Semiconductor chip is usually positioned in a reflector, so that the highest possible Proportion of the generated light energy for radiation in direction of action to disposal stands. To arrange the LED on an electronic board is the reflector according to SMD-capable (surface mounted device - SMD) educated. The underside of the SMD reflector housing is placed on the board, and the power supply connections are with corresponding lines connected to the board.

to Forming the light beam generated by the semiconductor chip is used optical body, its optically active zone, for example, a beam and focusing or beam broadening. Depending on Shape of the optical body are also other influences of the emitted from the semiconductor chip Light to generate a corresponding desired shape of the radiated Light beam possible. In most cases it is the optically active region of the optical body as focusing convex or jet-expanding concave, in each case rotationally symmetrical lens educated. The lens is of the semiconductor chip according to the optical Necessity arranged at a distance.

Of the Reflector on the one hand has the function of a housing that protects the assembly from external influences and the mechanical integration is used. It also reflects that Semiconductor chip facing surface of the housing the electromagnetic radiation emitted by the semiconductor chip and directs these to the optical body further. The space between the optical body, the said reflector surface and the semiconductor chip is filled with a potting compound, the among other things, the optical adaptation of the radiation path between Semiconductor chip, reflector and optical body is used.

Of the optical body becomes conventional pre-fabricated separately and when assembling the LED in the reflector used. The problem here is the correct position positioning of the optical body. On the one hand, the required distance between the semiconductor chip and optical body, with it the desired ones optical properties of the LED can be achieved. On the other hand must the lateral offset between reflector, semiconductor chip and optical body within the given specification. So it is desirable that the positioning of the optical body is positional relative to the remaining elements of the LED Complies with specifications.

Summary of the invention

A execution the light-emitting device is specified in claim 1.

By at least one support element, for example, be a stand can, who integrally with the optical body is connected, the distance between the semiconductor chip and optical body in the desired Tolerance range are set. The pedestal or several feet can on the one hand within the contour of the active area, for example the lens contour the optical body, with the optical body be connected or can outside this lens contour to be connected to the optical body. If a projection screen of the optical body For example, considered parallel to the semiconductor device, then the Feet inside the projection surface the optically active region of the optical body lie or outside.

If For example, the reflector is a rectangular, in the specific case, for example square, recess encloses, within which the optical body is to be positioned and within which also the semiconductor chip and the potting compound are arranged, then the feet can near the corners of the rectangle or square are arranged. Form the feet therefore a twist protection against incorrect position and positioning help for correct position Positioning of the optical body. In particular, the lens may be rotationally symmetrical, and put the feet outside the optically active lens contour and protrude into the corners of the reflector recess. The available Space is well utilized. This version serves as anti-twist protection or to the leadership the correctly positioned optimal positioning of the lens within the Reflector and relative to reflector and semiconductor chip.

In another embodiment, the recess of the reflector receiving the optical body may have a circular cross-sectional area, that is to say it may be cylindrical, for example be. Then set the feet below the example, rotationally symmetrical and cylindrical shaped optically active lens body, ie within the lens contour.

in the In the case of a circular recess in the reflector, three suffice Feet for safe Positioning of the lens body. In a rectangular or square recess four feet are appropriate. Combinations of the form the recess between said alternatives and the arrangement the feet relative to the lens body are possible and open up for according to the expert.

The Recess of the reflector has a base on which the feet with corresponding footprints support. The base area said recess may with respect to a main surface of the Semiconductor chips or re the flat, aufzusetzenden on the PCB boards back of the SMD-capable reflector housing be arranged in parallel. Likewise, the footprints of the Feet one parallel orientation to said plane.

In In other embodiments, the reflector may be an interior in the reflection included the emitted from the semiconductor chip electromagnetic radiation conical surface exhibit. A cross section through the reflector then shows one opposite to a Horizontal orientation of the housing or egg ner main plane of the semiconductor chip oblique course. In this Fall have the contact areas the feet on the slope or cone-shaped surface of the reflector on a correspondingly adapted orientation, so possible all Cross section of the feet against said oblique running footprint supported by the reflector. In this case, the footprints of the feet are on the Reflector also oblique formed to said main level.

Instead of a recess with a circular cross-section in the reflector housing can be a combination of circular and angular shape or a recess with elliptical Shape. Instead of a rectangular one or square cross-section can be provided a polygonal cross-section be. In the case of a polygonal cross section, the feet are ideally located near the corners of the polygon.

The Feet have a course that has at least a directional proportion, the points in the direction of the semiconductor chip. As a result, the feet put the distance between the lens and the semiconductor chip. Conveniently, the feet are vertical to the above horizontal oriented base of the Recess. It is also conceivable that the course of the feet one Direction portion which is perpendicular to one by the orientation of the semiconductor chip defined plane or perpendicular to the through the mounting surface specified level of the LED housing. The length the feet are like that set the light emitted from the semiconductor chip as well as that of the reflector walls reflected light is bundled or widened in the optical body, so that after radiation through the optical body a desired Beam shape results. For this it is necessary that the feet a corresponding length have, to the convenient, through the application offered distance between an optical axis of the optical body and adjust the light-emitting surface of the semiconductor chip.

Of the optical body can be made of silicone and is prefabricated. The potting compound between optical body, reflector surface and semiconductor chip, for example, is also made of a material formed with silicone portion. The reflector housing is made of plastic or from a multilayer ceramic. For example, comes for the reflector housing Injection-sprayed thermoplastic, a transfer-sprayed thermoset for example, epoxy-based or silicone-based in question. For the supply of electrical supply voltage are metallic leads in the reflector housing embedded and within the housing to the semiconductor chip bonded.

Below of the semiconductor chip can for heat dissipation thermally conductive Material in the reflector housing be arranged, for example, a thermally conductive plastic or a metallic material. Conveniently, this material to the for the SMD mounting provided housing back led and conducts the heat on the circuit board.

Of the Semiconductor chip can be opposite the base area, on the feet of the lens sit up, continue to reset be. For this purpose, a further recess within said Floor space be provided opposite the base area turn in the direction of the back of the reflector housing reset is. Within this recess is the heat-dissipating material, on which of the light-emitting semiconductor chip in operation with his back is applied.

Brief description of the drawings

The attached Figures show:

1A a plan view of a LED with a rectangular recess;

1B a cross section through the LED 1A along the line AA;

1C a cross section through the LED 1A along the line BB;

2A a plan view of a LED with a circular recess;

2 B a cross section through the LED 2A along the line AA;

2C a cross section through the in the LED 2A included lens along the line BB;

3 a cross section through an LED with a conical reflector geometry.

Detailed description of embodiments

following The invention will be described with reference to various embodiments for LEDs. It is attached to the Drawings reference. Corresponding elements in different Figures are provided with the same reference numerals. The shown Representations only schematically show the proportions. Especially The illustrations shown are not to scale.

1A shows a plan view of a light-emitting device, LED. The illustrated LED includes a reflector housing 11 in which or relative to which the individual elements of the LED are attached. Because the reflector housing 11 All elements of the LED fixed to each other in the correct position, it is also here as a support element 11 designated. In supervision is the lens 10 to recognize the inside of the rectangular, specially designed square recess 121 is arranged. The Lens 10 is designed as a converging lens to focus light, which consists of a semiconductor chip, in the representation shown below the lens 10 is arranged, is broadcast. Laterally on the lens 10 are feet 103 . 104 . 105 . 106 appropriate. These are integral with the lens 10 connected. Because the optically active area of the lens 10 is formed circular in horizontal cross section through the lens is in the space between the lens and one of the corners 122 . 123 . 124 . 125 the recess 121 enough space around the feet attached to the side of the lens 104 , ..., 106 take. There are with rectangular recess 4 (four) feet provided. In cross-section are the feet 103 , ..., 106 turn circular or elliptical, so that they the space between the lens and the respective corner of the recess 121 fill well. The respective feet 103 , ..., 106 are each near a corner of the recess 121 arranged.

On the side, respective connections run 131 . 132 for each one pole of a supply voltage to supply the LED with electrical power. The connecting cables 131 . 132 are made of metal.

A cross-sectional view along the section line AA represents 1B There is the semiconductor chip 141 shown, which consists of a suitable semiconductor layer structure in order to supply voltage across the lines 131 . 132 be stimulated according to the emission of light. In detail, the recess 121 shown having substantially vertical side walls in the illustrated orientation. These serve as a reflector for the semiconductor chip 141 emitted light. The semiconductor chip 141 emits both light upwards, which from the lens 10 is bundled and focused is radiated. Depending on the opening angle of the light emission of the semiconductor chip 141 Light also reaches the surfaces of the vertical side walls 111 the recess 121 , which is then passed through the lens 10 is focused. For this purpose, the surfaces of the side walls are coated with a reflective material as possible.

Between semiconductor chip 141 , Recess 121 and lens 10 is a potting compound 12 arranged, which among other things the optical adjustment (index match) serves as well as for the attachment of the lens 10 in the reflector. Inside the recess 121 is another recess 126 reset, in which the semiconductor chip 141 is arranged. The further recess 126 can also be omitted in other versions. The recess 126 is from an element 112 made of thermally conductive material, which is fitted in the reflector back. The material element 112 serves to that of the semiconductor chip 141 dissipate generated heat of operation. Finally, the laterally voltage-supplying metallic conductor tracks 131 . 132 shown. The conductor track 131 is over a bonding wire 142 with the top of the semiconductor chip 141 connected. The conductor track 132 abuts the heat-conducting element 112 , At the same time is the element 112 also electrically conductive to the electrical contact with the back of the semiconductor chip 114 connected. Here is the track 132 to the element 112 bonded (not shown).

The reflector housing shown 11 is used in the application preferably for surface mounting on a printed circuit board. This is the back 115 Plan executed so that the support surface 115 can be placed on the circuit board.

The reflector housing 11 is made of plastic, for example by injection injection thermoplastic or a transfer-sprayed thermoset, which can be produced on an epoxy or silicone basis. Alternatively, a multilayer ceramic can be used. The potting compound 12 is silicone based and of soft toughness. The Lens 10 can also be formed from silicone with respect to the potting compound 12 harder consistency.

1C makes a cut through the LED 1A along the line BB. The cut is through the feet 103 . 104 guided. You can see that the base 103 via a connector 102 with the optically active part of the lens 10 connected is. During the production of the lens 10 become optically active body 10 and feet 103 , ..., 106 made of silicone by syringes, transfer syringes or compression in one piece.

The feet 103 . 104 in 1C (as well as the feet 105 . 106 ) are outside the optically active part 10 the lens structure. For example, if the lens 10 including the optically active region 10 and the feet mounted integrally thereon on a horizontal plane 118 projected, lie the projection surfaces 103 ' . 104 ' the feet outside the projection area 119 for the optically active part of the lens 10 , The horizontal projection plane 118 is for example through the back 115 of the SMD housing defined or by the light-emitting surface 143 of the semiconductor chip 141 ,

During manufacture, the reflector housing is first 11 provided, then the semiconductor chip 141 introduced and bonded accordingly. Subsequently, the potting compound 12 injected, then into the still soft potting compound 12 the prefabricated lens body 10 including feet 103 , ..., 106 use. In the case shown, the recess 121 in the reflector housing 11 is rectangular and the lens 10 is formed rotationally symmetrical with a circular cross section, fit the feet 103 , ..., 106 exactly in the space between lens body 10 and respective corner of the recess. As a result, a twist protection is given insofar that the lens only four possible positions relative to the reflector housing 11 can take.

The feet have in the embodiment shown in relation to the horizontal plane 118 vertical orientation. The feet have a footprint 107 on, which on the lower side 117 on a base 113 the recess 121 supports itself. The length of the feet is set so that the intended optical effect for that of the semiconductor chip 141 emitted light results. In addition, the length of the feet is such that the potting compound 12 the approach of the feet on the lens body 10 still slightly over covers. A part of the optically active region of the lens body 10 surmounted so the upper end of the reflector housing. If spoken in this description from above or below, this information is on the support surface 115 of the SMD-compatible reflector housing 11 based. In general, it is sufficient if the feet each have a longitudinal course, which has a directional portion which extends in the direction of the semiconductor chip. Here includes the vertical orientation with respect to the plane 118 such a directional proportion.

The feet 103 , ..., 106 the lens 10 in practice have a length in the range of 1.0 mm (millimeters) to 0.3 mm. The horizontal diameter in the direction of the plane 118 the lens 10 depends on the desired beam shaping. In principle, the lens 10 as shown in the example to be designed as focusing optics. Alternatively, it is also possible to use the lens 10 to dimension for a beam-expanding optics. A typical lens diameter may be 5 mm or less, the latter being particularly suitable for focusing optics. With expanding optics, the lens diameter can be quite 10 mm.

As shown below the lens 10 a semiconductor chip arranged. In alternative embodiments, it is also possible to use chip arrays which comprise a plurality of LED semiconductor components in a matrix arrangement or row arrangement. Then, however, the lateral dimensions of the lens and the recess in the reflector housing are correspondingly larger than for the embodiment with only a single semiconductor chip.

In the 2A shown in plan LED has a reflector body 21 on, the one in plan circular recess 121 contains, in which the reflector surface is formed and in which the lens body 20 located. Because the lens body 20 also seen horizontally has a circular cross-sectional area and circular outer contour, the lens adjusts 20 good in the circular cross-section of the reflector recess 121 one. The distance between the edge of the lens body 20 and reflector 121 has almost constant size over the circumference. Here are the feet 203 . 204 . 205 connected within the lens contour with the active part of the lens. With round recess 121 At least 3 feet are provided. As in connection with the 1A shown serve metallic tracks 231 . 232 for supplying supply voltage and electrical power to the semiconductor chip.

The in 2 B illustrated cross section through the reflector body along the line AA is similar to the representation in 1B except that in 2 B of the Lensenkörper is omitted for clarity. In 2C Finally, the lens body 20 out 2A shown in section along the line BB. The feet 203 . 204 . 205 are perpendicular with respect to the reference plane 218 passing through the surface of the semiconductor chip 241 or through the flat back 215 of the SMD-capable reflector housing is fixed. When projecting the lens 20 to the level 218 it should be noted that the feet 203 . 204 . 205 all within the projection area 219 for the lens 20 lie. This is necessary because the outer contour 20 the lens fits well with the inner surface of the reflector recess 121 completes and compared with the 1A with square recess an additional space for holding the lens feet is not present.

To complete the LED, in a further step, the in 2C shown lens body 20 in the recess 121 that like in 2 B already shown with potting compound 22 filled, used. Since the arrangement is rotationally symmetric, the lens can 20 be used in any rotated orientation.

Finally, in 3 another embodiment shown in cross section. The reflector body 31 has a reflector recess 321 on whose side walls contrary to the representations in 1B and 2 B one compared to the horizontal reference plane 318 have oblique course. The side walls of the recess 321 makes an angle 317 with the horizontal plane 318 , Again, the horizontal plane 318 through the flat SMD-capable back 315 of the reflector housing 31 or through the upper surface of the semiconductor chip 314 established. The Lens 30 points according to the lens 20 out 2C stands 304 . 305 as shown in cross-section, below the optically active region of the lens 30 are arranged. The side wall of the recess 321 is the surface of a truncated cone. The feet 304 . 305 rely on the side walls of the reflector recess 321 in the area 316 from. In the example shown, the feet have a footprint 307 on the base 316 the reflector recess 321 on, which is also the angle 317 to the horizontal 318 forms. The length of the feet 304 . 305 is designed to match the required distance between lens body 30 and surface of the semiconductor chip 314 so that the appropriate focusing effect through the lens 30 is reached.

The angle 317 is pointed, that is smaller than 90 °, preferably the angle is 317 between 40 ° and 60 °, more preferably at about 45 °.

Claims (17)

Light-emitting device, comprising: a carrier element ( 11 . 21 . 31 ); a semiconductor device suitable for emitting light ( 114 . 314 ), which relative to the support element ( 11 . 21 . 31 ) is attached; an optical body ( 20 . 30 ) adapted to guide light emitted by the semiconductor device in operation; a potting compound ( 22 . 32 ) disposed between the semiconductor device and the optical body; at least one support element ( 103 . 104 . 105 . 106 ; 203 . 204 . 205 ; 304 . 305 ) integral with the optical body ( 20 . 30 ) and extends in a direction one towards the semiconductor device ( 114 . 314 ) directed directional share. A light-emitting device according to claim 1, wherein the optical body ( 20 ) an optically active region ( 20 ), wherein a projection surface ( 219 ) of the optically active region in a plane oriented parallel to the semiconductor device ( 218 ) and the at least one support element ( 203 . 204 . 205 ) a connection zone with the optical body ( 20 ) which, when projected within the projection surface ( 219 ) lies. A light-emitting device according to claim 1, wherein the optical body ( 10 ) an optically active region ( 10 ), wherein a projection surface ( 119 ) of the optically active region parallel to the semiconductor device ( 114 ) oriented level ( 118 ) and the at least one support element ( 103 ) a connection zone ( 102 ) with the optically active region of the optical body, which at projection ( 103 ' ) outside the projection surface ( 119 ) of the optically active region. Light-emitting device according to one of Claims 1 to 3, in which the carrier element ( 11 . 21 . 31 ) is a reflector which in operation reflects light emitted by the semiconductor device in the direction of the optical body. Light-emitting device according to one of Claims 1 to 4, in which the carrier element ( 11 ) a recess with a base ( 113 ) and one of the base ( 113 ) surrounded further recess ( 126 ), in which the semiconductor component ( 114 ), wherein the at least one support element ( 103 . 104 . 105 . 106 ) the base area ( 113 ) contacted. Light-emitting device according to one of Claims 1 to 4, in which the carrier element ( 11 ) a rectangular recess ( 121 ) and the at least one support element ( 103 . 104 . 105 . 106 ) near one of the corners ( 122 . 123 . 124 . 125 ) of the rectangular recess is arranged. Light-emitting device according to one of Claims 1 to 6, in which the carrier element ( 21 ) a rectangular recess ( 121 ) and four similar support elements ( 103 . 104 . 105 . 106 ) are connected to the optical body, wherein the support elements in a space between one or the optically active region of the optical body and one of the corners ( 122 . 123 . 124 . 125 ) are arranged the Reckeckförmigen recess. Light-emitting device according to one of Claims 1 to 4, in which the carrier element ( 21 ) has a circular recess or an elliptical recess and the support element ( 203 . 204 . 205 ) between the semiconductor device ( 114 ) and a recess bounding the edge surface ( 121 ) on the support element ( 21 ) is supported. Light-emitting device according to claim 5, in which a distance between the base area ( 113 ) and a lower side of the optical body ( 10 ) is given and the at least one support element ( 103 . 104 . 105 . 106 ) between the optical body and the base surface ( 113 ) and the base area ( 113 ) contacted to support the optical body. Light-emitting device according to one of Claims 1 to 9, in which the carrier element ( 11 ) a support surface ( 115 ), which is suitable for mounting on an electronic circuit board, further comprising a recess ( 121 ), which from the support surface ( 115 ) facing away from the surface and the edge is bounded by a surface of the support element, further from the stand surface facing away from the end of the support element is present, wherein the optical body ( 20 ) the opposite end of the support element ( 21 ) partly surmounted. A light-emitting device according to claim 10, wherein the at least one support element ( 103 . 104 . 105 . 106 ) has a proportion which is perpendicular to the support surface ( 115 ) runs. Light-emitting device according to one of Claims 1 to 11, in which the at least one support element ( 103 . 104 . 105 . 106 ) is a pedestal which is located at an edge of one or the optically active region of the optical body ( 10 ) with the optically active region ( 10 ) and at least partially along a direction of a between the semiconductor device ( 114 ) and the optical body ( 10 ) extending distance runs. A light-emitting device according to claim 1, wherein the optical body ( 10 ) has a circular cross-sectional area ( 119 ) and the at least one support element ( 103 . 104 . 105 . 106 ) in a direction perpendicular to the cross-sectional area ( 119 ), wherein the at least one support element is a surface of the support element ( 21 ) is contacted to the optical body ( 10 ) support against the support element. A light-emitting device according to claim 1, in which the carrier element ( 31 ) a recess with an oblique side wall ( 321 ), wherein an acute angle ( 117 ) with a through a main surface of the semiconductor device ( 314 ) level ( 318 ), wherein the at least one support element ( 304 . 305 ) a stand area ( 307 ), which the oblique side wall ( 321 ), wherein the footprint ( 307 ) at said angle ( 117 ) to the level ( 318 ) runs. Light-emitting device according to one of Claims 1 to 14, in which the optical body ( 10 ) is formed of silicone. A light-emitting device according to claim 15, wherein one or the optically active region of the optical body ( 10 ) is rotationally symmetrical. Light-emitting device according to one of claims 1 to 16, the plurality of semiconductor devices suitable for emitting light which positions relative to one another in a matrix arrangement are and emit in operation light, which radiates through the optical body.