Patent Publication Number: US-2016240747-A1

Title: Optoelectronic component and method of production thereof

Description:
TECHNICAL FIELD 
     This disclosure relates to an optoelectronic component and a method of producing an optoelectronic component. 
     BACKGROUND 
     Optoelectronic components in which an optoelectronic semiconductor chip, for example, a light-emitting diode chip (LED chip) is arranged in a cavity of a housing, are known. The cavity is filled with an encapsulation material in which the optoelectronic semiconductor chip is embedded. During production of such optoelectronic components, cavities of a continuous panel of a multiplicity of housings are simultaneously filled with encapsulation material. The encapsulation may, for example, be carried out by compression molding. The encapsulation material is thus distributed beyond the edges of the cavities, between the housings of the panel. To this end, a sufficient space, which is likewise filled with the encapsulation material, must be provided over the edges of the cavities of the housing. That part of the encapsulation material remaining over the housings of the optoelectronic components increases material costs, leads to a reduction in efficiency and makes it more difficult to divide the optoelectronic components. 
     SUMMARY 
     We provide an optoelectronic component including a housing body, wherein a cavity is formed on an upper side of the housing body, and a channel extending from the cavity to an outer edge of the upper side of the housing body is formed on the upper side of the housing body. 
     We also provide a method of producing an optoelectronic component including providing a flat panel of a multiplicity of housing bodies, each housing body having a cavity opening onto an upper side of the panel, wherein the cavities of neighboring housing bodies connect by channels and open onto the upper side of the panel, arranging an encapsulation material in the cavities of the housing bodies, and dividing the panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a plan view of a panel of a multiplicity of housing bodies. 
         FIG. 2  shows a section through the panel. 
         FIG. 3  shows a plan view of an optoelectronic component. 
         FIG. 4  shows a section through the optoelectronic component. 
     
    
    
     LIST OF REFERENCES 
     
         
           100  panel 
           101  upper side 
           110  separating plane 
           200  housing body 
           201  upper side 
           202  outer edge 
           210  cavity 
           211  bottom region 
           220  channel 
           300  lead frame 
           301  upper side 
           302  lower side 
           400  encapsulation material 
           410  volume section 
           420  cover layer 
           421  thickness 
           430  optical lens 
           500  optoelectronic semiconductor chip 
           501  upper side 
           502  lower side 
           510  bonding wire 
           600  optoelectronic component 
           610  housing 
       
    
     DETAILED DESCRIPTION 
     Our optoelectronic component comprises a housing body on the upper side of which a cavity is formed. Furthermore, a channel extending from the cavity to an outer edge of the upper side of the housing body is formed on the upper side of the housing body. Advantageously, the cavity of the housing body of the optoelectronic component may be filled with an encapsulation material through the channel during the production of the optoelectronic component. 
     In the optoelectronic component, an optoelectronic semiconductor chip may be arranged on a bottom region of the cavity. The optoelectronic semiconductor chip may, for example, be a light-emitting diode chip (LED chip). The cavity of the housing of the optoelectronic component may form a reflector for the electromagnetic radiation emitted by the optoelectronic semiconductor chip of the optoelectronic component, and collimate this radiation. Arrangement of the optoelectronic semiconductor chip on the bottom region of the cavity of the housing advantageously protects the optoelectronic semiconductor chip against damage by external mechanical effects. 
     An encapsulation material may be arranged in the cavity and the channel. Advantageously, the encapsulation material can enter the cavity through the channel during production of the optoelectronic component so that the optoelectronic component can advantageously be produced particularly simply. The encapsulation material arranged in the cavity may advantageously be used as additional protection for an optoelectronic semiconductor chip arranged in the cavity and embedded in the encapsulation material. 
     The encapsulation material may comprise silicone. In this way, the encapsulation material is advantageously economically obtainable and simple to process. Furthermore, the encapsulation material may be configured to be optically essentially transparent for electromagnetic radiation emitted by an optoelectronic semiconductor chip of the optoelectronic component. 
     The encapsulation material may comprise embedded wavelength-converting particles. The wavelength-converting particles embedded in the encapsulation material may be provided to convert a wavelength of electromagnetic radiation emitted by an optoelectronic semiconductor chip of the optoelectronic component. To this end, the wavelength-converting particles may be configured to absorb electromagnetic radiation with a first wavelength and subsequently emit electromagnetic radiation with a second, typically longer, wavelength. The wavelength-converting particles may, for example, comprise an organic or inorganic luminescent material. The wavelength-converting particles may also comprise quantum dots. 
     The encapsulation material may extend over the upper side of the housing body and form a layer there. Advantageously, the layer can likewise contribute to filling the cavity with the encapsulation material during production of the optoelectronic component. 
     A section arranged over the housing body of the layer may have a thickness of less than 100 μm, preferably a thickness of less than 50 μm. Advantageously, only a very small part of electromagnetic radiation emitted by an optoelectronic semiconductor chip of the optoelectronic component is lost in a layer with such a small thickness. Furthermore, only a very small amount of encapsulation material is required to form such a thin layer. 
     The optoelectronic component may comprise an optical lens arranged over the cavity. The optical lens may, for example, be configured as a converging lens or as a diverging lens. The optical lens may advantageously be used to shape a light beam emitted by the optoelectronic component. 
     The lens may be integrally formed with the encapsulation material. In this way, the lens can advantageously be produced particularly simply and economically. In particular, it is possible to form the lens simultaneously with filling the cavity of the housing body of the optoelectronic component with the encapsulation material. 
     A method of producing an optoelectronic component has steps of providing a flat panel of a multiplicity of housing bodies, each housing body having a cavity opening onto an upper side of the panel, the cavities of neighboring housing bodies being connected by channels opening onto the upper side of the panel, arranging an encapsulation material in the cavities of the housing bodies, and dividing the panel. Advantageously, this method allows parallel production of a multiplicity of optoelectronic components so that low production costs per optoelectronic component are achieved. During arrangement of the encapsulation material in the cavities of the housing bodies, the encapsulation material may advantageously enter the cavities of the housing bodies through the channels. A space arranged over the upper side of the panel for distribution of the encapsulation material can advantageously be configured to be particularly small so that the method is advantageously associated with minimal consumption of encapsulation material. Furthermore, in the optoelectronic components which can be obtained by the method, only a thin layer of encapsulation material is therefore formed over the upper side of the housing bodies so that brightness losses due to this layer are small. 
     The method may comprise a further step, carried out before arrangement of the encapsulation material, of arranging an optoelectronic semiconductor chip on a bottom region of the cavity of a housing body. Advantageously, the optoelectronic semiconductor chip in the cavity of the housing body is embedded in the encapsulation material so that the optoelectronic semiconductor chip is protected against subsequent damage by external mechanical effects. 
     The encapsulation material may flow at least partially through the channels during arrangement of the encapsulation material. Advantageously, the encapsulation material can enter the cavities of the plurality of housing bodies in a simple way so that reliable filling of all the cavities can be ensured. 
     The encapsulation material may be arranged by compression molding in the cavities. Advantageously, this allows the method to be carried out economically. 
     Provision of the flat panel may comprise forming the panel by injection molding. Advantageously, this allows economical production of the flat panel of the multiplicity of housing bodies. 
     Division of the panel may be carried out along separating planes oriented perpendicularly to the channels. In this way, it is advantageously necessary to divide only short sections of the encapsulation material during division of the panel so that the division can be carried out in a simple one-stage process. 
     The above-described properties, features and advantages, as well as the way in which they are achieved, will become more clearly and comprehensively understandable in connection with the following description of examples, which will be explained in more detail in connection with the drawings. 
       FIG. 1  shows a schematic plan view of a panel  100  of housing bodies  200 .  FIG. 2  shows a schematic sectional side view of the panel  100 . 
     The panel  100  comprises a multiplicity of the housing bodies  200 . The housing bodies  200  are arranged in a regular arrangement in the panel  100  and are connected to one another. In the example represented in the figures, the panel  100  comprises an array of 3×5 housing bodies  200 . The panel  100  could, however, also comprise a substantially larger number of housing bodies  200 . 
     The housing bodies  200  are arranged an upper side  301  of a lead frame  300  represented only schematically in the figures. The lead frame  300  comprises an electrically conductive material, for example, a metal. The lead frame  300  is configured as a substantially flat plate with the upper side  301  and a lower side  302  opposite the upper side  301 . In the lateral direction, the lead frame  300  may have structuring with openings, formed between the upper side  301  and the lower side  302 , which subdivides the lead frame  300  in the lateral direction into sections electrically insulated from one another. 
     The connected housing bodies  200  of the panel  100  comprise an electrically insulating material, for example, a plastic material. The housing bodies  200  may, for example, comprise an epoxide. The housing bodies  200  may, for example, have been formed by injection molding on the upper side  301  of the lead frame  300 . 
     The connected housing bodies  200  of the panel  100  comprise an upper side  201  facing away from the upper side  301  of the lead frame  300 . The upper sides  201  of the connected housing bodies  200  of the panel  100  together form an upper side  201  of the panel  100 . 
     Each housing body  200  of the panel  100  has a cavity  210  opening onto the upper side  201  of the respective housing body  200 . The cavity  210  extends from the upper side  201  of the housing body  200  into the housing body  200  as far as the upper side  301  of the lead frame  300 . The upper side  301  of the lead frame  300  therefore forms a bottom region  211  of the cavity  210 . In the lateral direction of the panel  100 , the cavities  210  may, for example, have rectangular or, as represented, discoid cross-sectional surfaces. The walls of the cavity  210  extending between the bottom region  211  of a cavity  210  and the upper side  201  of the respective housing body  200  may, as represented, be perpendicularly oriented. The cavities  210  could, however, for example, also widen from the bottom region  211  toward the upper side  201 . 
     The cavities  210  of neighboring housing bodies  200  of the panel  100  respectively connect to one another by channels  220 . The channels  220  extend from the upper sides  201  of the housing bodies  200  into the housing bodies  200 , but while preferably not reaching the upper side  301  of the lead frame  300 . Bottom regions of the channels  220  are preferably formed by the material of the connected housing bodies  200  of the panel  100 . The channels  220  preferably extend in a straight line on the shortest path between the cavities  210  of neighboring housing bodies  200 . Perpendicularly to its longitudinal extent direction oriented from one cavity  210  to the next cavity  210 , each channel  220  has a width preferably much less than the lateral diameter of the cavities  210 . 
     In the example represented in  FIGS. 1 and 2 , the housing bodies  200  of the panel  100  are arranged in a regular rectangular arrangement of rows and columns. The channels  220  extend both row-wise and column-wise between the cavities  210  of housing bodies  200  neighboring one another. In this way, for each housing body  200  of the panel  100  except for housing bodies  200  arranged on an outer edge of the panel  100 , the cavity  210  connects via four channels  220  to the cavities  210  of four neighboring housing bodies  200 . It is, however, also possible to omit some of the channels  220  and arrange channels  220 , for example, only column-wise or only row-wise. It would likewise be possible to provide additional diagonal channels  220  connecting to one another the cavities  210  of housing bodies  200  neighboring at their corner. It is likewise possible to arrange the housing bodies  200  of the panel  100  in an arrangement other than a rectangular arrangement. In this case as well, the cavities  210  of the housing bodies  200  connect to one another via channels  220 . 
     The cavities  210  and the channels  220  of the housing bodies  200  are preferably already formed during production of the panel  100  of housing bodies  200 . This may, for example, be done by injection molding using a suitable mold during production of the panel  100  of housing bodies  200 . 
     An optoelectronic semiconductor chip  500  is respectively arranged on the bottom region  211  of the cavity  210  of each housing body  200 . The optoelectronic semiconductor chips  500  may, for example, be light-emitting diode chips (LED chips). Each optoelectronic semiconductor chip  500  has an upper side  501  and a lower side  502  opposite the upper side  501 . Each optoelectronic semiconductor chip  500  is configured to generate electromagnetic radiation, for example, visible light and emit this on its upper side  501 . Each optoelectronic semiconductor chip  500  is arranged on the bottom region  211  of a cavity  210  of a housing body  200  such that the lower side  502  of the optoelectronic semiconductor chip  500  faces toward the bottom region  211  of the cavity  210 . In this case, the lower side  502  of the optoelectronic semiconductor chip  500  may, for example, connect by an electrically conductive connecting medium, for instance a solder or an electrically conductive adhesive, to the upper side  301  of a section of the lead frame  300 . 
     In each optoelectronic semiconductor chip  500 , a first electrical contact pad is formed on the upper side  501 . A second electrical contact pad of the optoelectronic semiconductor chip  500  may, for example, be formed on the lower side  502  of the optoelectronic semiconductor chip  500 . In each optoelectronic semiconductor chip  500 , an electrical voltage may be applied to the optoelectronic semiconductor chip  500  between the first electrical contact pad and the second electrical contact pad to make the optoelectronic semiconductor chip  500  emit electromagnetic radiation. In each optoelectronic semiconductor chip  500 , the first electrical contact pad formed on the upper side  501  electrically conductively connects by a bonding wire  510  to a section of the lead frame  300 . The bonding wire  510  preferably extends entirely inside the cavity  210  of the respective housing body  200 . The second electrical contact pad, arranged on the lower side  502 , may in each optoelectronic semiconductor chip  500  electrically conductively connect to a section of the lead frame  300 , for example, by the electrically conductive connecting medium between the optoelectronic semiconductor chip  500  and the upper side  301  of the lead frame  300 . 
     The arrangement of the optoelectronic semiconductor chips  500  in the cavities  210  of the housing bodies  200  of the panel  100  is preferably carried out after the formation of the housing bodies  200  of the panel  100 . Application of the bonding wires  510  is then carried out. 
     The cavities  210  of the housing bodies  200  of the panel  100  are filled with an encapsulation material  400 . The channels  220  are also filled with the encapsulation material  400 . The optoelectronic semiconductor chips  500  arranged in the cavities  210  of the housing bodies  200  of the panel  100  and the bonding wires  510  connected to the optoelectronic semiconductor chip  500  are embedded in the encapsulation material  400 . In this way, the encapsulation material  400  protects the optoelectronic semiconductor chips  500  and the bonding wires  510  against damage by external mechanical effects, as well as against ingress of dirt and moisture. 
     The encapsulation material  400  comprises a material essentially optically transparent for electromagnetic radiation emitted by the optoelectronic semiconductor chips  500 . For example, the encapsulation material  400  may comprise silicone. The encapsulation material  400  may furthermore comprise embedded wavelength-converting particles intended to convert a wavelength of electromagnetic radiation emitted by the optoelectronic semiconductor chips  500 . To this end, the wavelength-converting particles embedded in the encapsulation material  400  may be configured to absorb electromagnetic radiation with a first wavelength and subsequently emit electromagnetic radiation with a second, typically longer, wavelength. In this way, the wavelength converting particles embedded in the encapsulation material  400  may, for example, be configured to convert blue light generated by the optoelectronic semiconductor chips  500  into white light. The wavelength-converting particles embedded in the encapsulation material  400  may, for example, comprise an organic luminescent material or inorganic luminescent material. The wavelength-converting particles may also comprise quantum dots. 
     The encapsulation material  400  preferably fills the cavities  210  of the housing bodies  200  of the panel  100  fully. In each cavity  210 , a volume section  410  of the encapsulation material  400 , in which the optoelectronic semiconductor chip  500  and the bonding wire  510  are embedded, is arranged. 
     In addition, the encapsulation material  400  also extends over the upper sides  201  of the housing bodies  200  of the panel  100 . A part of the encapsulation material  400 , arranged over the upper sides  201  of the housing bodies  200  of the panel  100 , forms a cover layer  420 . The cover layer  420  therefore connects the volume sections  410  of the encapsulation material  400  arranged in the cavities  210  of neighboring housing bodies  200  of the panel  100 . In addition, the volume sections  410  of the encapsulation material  400  arranged in the cavities  210  of neighboring housing bodies  200  connect to one another by parts of the encapsulation material  400  arranged in the channels  220 . 
     The cover layer  420  of the encapsulation material  400  arranged above the upper sides  201  of the housing bodies  200  of the panel  100  has a thickness  421  in a direction perpendicular to the upper sides  201  of the housing bodies  200 . Preferably, the thickness  421  of the cover layer  420  is less than 100 μm. Particularly preferably, the cover layer  420  has a thickness  421  of less than 50 μm. 
     An optical lens  430  is arranged over the cavity  210  of each housing body  200  of the panel  100 . The optical lens  430  is arranged above the cover layer  420  of the encapsulation material  400  and preferably consists of the encapsulation material  400 . The optical lenses  430  may be formed during introduction of the encapsulation material  400  into the cavities  210  of the housing bodies  200  of the panel  100 . The optical lenses  430  are preferably configured as converging lenses, although they may also be configured as diverging lenses or in a different manner. The optical lenses  430  may be used for beam shaping of the electromagnetic radiation emitted by the optoelectronic semiconductor chips  500 . For example, the optical lenses  430  may be used for collimation of the electromagnetic radiation emitted by the optoelectronic semiconductor chips  500 . 
     Introduction of the encapsulation material  400  into the cavities  210  of the housing bodies  200  of the panel  100  may, for example, be carried out by compression molding. In this case, the encapsulation material  400  may be distributed via the channels  220  between the cavities  210  of the individual housing bodies  200  of the panel  100 . The encapsulation material  400  in this case flows through the channels  220 . To a lesser extent, the encapsulation material  400  may also be distributed via the cover layer  420  over the upper sides  201  of the housing bodies  200  of the panel  100 . The channels  220  ensure that the cavities  210  of all the housing bodies  200  of the panel  100  are fully filled by the encapsulation material  400 . 
     After the cavities  210  of the housing bodies  200  of the panel  100  have been filled with the encapsulation material  400 , the housing bodies  200  may be separated from one another by dividing the panel  100 . To this end, the panel  100  is separated along separating planes  110 . The separating planes  110  extend between the housing bodies  200 . In the rectangular arrangement of the housing bodies  200  as represented in  FIGS. 1 and 2 , the separating planes  110  extend between the rows and columns of the housing bodies  200 . The separating planes  110  pass through the channels  220  of the housing bodies  200  of the panel  100 . In this case, the channels  220  are cut by the separating planes  110  perpendicularly to their longitudinal direction oriented from one cavity  210  to the next cavity  210 . 
     The division of the panel  100  may, for example, be carried out by a sawing process. In this case, the saw cuts extend essentially through the material of the housing bodies  200  of the panel  100  and only in the region of the narrow channels  220  and in the region of the cover layer  420  through the encapsulation material  400 . This can make it possible to ignore a hardness difference between the material of the housing bodies  200  and the encapsulation material  400 , and to carry out division of the panel  100  along the separating planes  110  in a one-stage sawing process. This possibility is reinforced in particular by the small thickness  421  of the cover layer  420  arranged over the upper sides  201  of the housing bodies  200  of the encapsulation material  400 . Division of the panel  100  may, however, also be carried out, for example, in a two-stage sawing process in which the cover layer  420  of the encapsulation material  400  is divided in one stage and the housing bodies  200  of the panel  100  are divided in a further stage. 
       FIG. 3  shows a schematic plan view of an optoelectronic component  600  formed from a part of the divided panel  100 .  FIG. 4  shows a schematic sectional side view of the optoelectronic component  600 . The optoelectronic component  600  has a housing  610  formed by a housing body  200  of the panel  100 , a section of the lead frame  300 , and the encapsulation material  400  arranged in the cavity  210  of the housing body  200  and the channels  220  of the housing body  200 . The housing  610  encloses the optoelectronic semiconductor chip  500  of the optoelectronic component  600  arranged in the cavity  210  of the housing body  200 . 
     The upper side  201  of the housing body  200  of the housing  610  of the optoelectronic component  600  has outer edges  202  formed by dividing the panel  100  along the separating planes  110 . The channels  220  of the housing body  200  of the housing  610  of the optoelectronic component  600  extend from the cavity  210  of the housing body  200  to the outer edges  202  of the housing body  200 . 
     The optoelectronic component  600  may, for example, be intended as an SMD component for surface mounting. For example, the optoelectronic component  600  may be intended for mounting by reflow soldering. To this end, two solder contact pads electrically conductively connected to the two electrical contact pads of the optoelectronic semiconductor chip  500  of the optoelectronic component  600 , may be formed on the lower side  302  of the lead frame  300  of the housing  610  of the optoelectronic component  600 . 
     It is also possible to form the housing bodies  200  arranged in the panel  100  from a ceramic material. In this case, the lead frame  300  may be omitted. Each housing body  200  of the panel  100  may have embedded electrically conductive vias extending between the bottom region  211  of the cavities  210  of the respective housing body  200  and a lower side of the housing body  200 , lying opposite the upper side  201  of the respective housing body  200 . The channels  220  may be configured as indentations in the substrate of the housing body  200  which may, for example, be introduced by a laser or by using multilayer ceramics. In a panel  100  of housing bodies  200  formed in this way, the rest of the structure and the further processing correspond to that described with the aid of  FIGS. 1 to 4 . 
     Our components and methods have been illustrated and described in detail with the aid of the preferred examples. Nevertheless, this disclosure is not restricted to the examples disclosed. Rather, other variants may be derived therefrom by those skilled in the art without departing from the protective scope of the disclosure. 
     This application claims priority of DE 10 2013 220 960.6, the subject matter of which is incorporated herein by reference.