Abstract:
A light-emitting diode includes a cup component, a plurality of electrical conducting traces formed on a surface of the cup component using an MID means, a light-emitting diode chip mounted on the cup component and electrically connected to at least a first and second electrical conducting trace of the plurality of electrical conducting traces, and a first connection part connected to at least the first and second electrical conducting traces for providing electrical connections to external circuitry. The light emitting diode may also include a protective element that electrically protects the light-emitting diode chip, and the connection part may include first and second leads connected electrically to the first and second electrical conducting traces, respectively. The cup component, light emitting diode chip, protective element, leads and other components may be assembled together and molded and sealed with resin.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to an assembled light-emitting diode that houses a light-emitting diode chip (hereafter referred to as an LED chip).  
           [0003]    2. Discussion of the Background Art  
           [0004]    Light-emitting diodes that contain a pair of leads and LED chips that are connected electrically to the leads are known conventionally and various improvements have been made for the purpose of improving their performance and manufacturing yields. Conventional examples of this type of light-emitting diode are described in Japanese Patent Nos. 2,982,553 and 2,922,977. The example described in the former document is shown in FIG. 1( a ) of the figures of this application and the example described in the latter is shown in FIG. 1( b ). These figures show the cross-sectional structure in the vicinity of the LED chip-mounting portion.  
           [0005]    In the example shown in FIG. 1 (a), an improvement is made for the purpose of preventing electrical short circuits between leads. As shown in FIG. 1( a ), the LED chip  510  has a pair of electrodes  520  and  530  on its bottom surface and these electrodes are electrically connected by connecting means  525  and  535  such as solders to the pair of leads  560  and  570 . The insulating material  595  is placed between the leads  560  and  570  for the purpose of preventing short circuits between them. This insulating material can also decide a relative position of the two leads  560  and  570 .  
           [0006]    The cup component  650 , which comprises an insulator that is linked to the tip of the pair of leads  660  and  670 , is shown in FIG. 1( b ). The cup component  650  is placed so that it engages with the shoulders  661  and  671  that are formed in the leads  660  and  670 . The reflecting surface  623  that is formed inclined to the inside surface of the apex of the cup component  650  is constructed so that it can collect the emitted light from the LED chip  610  and reflect it upwards.  
           [0007]    According to the construction of the light-emitting diodes shown in these prior documents, the LED chips are connected to the leads  560  and  570 ;  660  and  670  in the vicinity of the tips of the leads  560  and  570 ;  660  and  670  at which the LED chips  510  and  610  are arranged, after which a resin mold is formed to protect them. In FIG. 1( b ), the resin mold is shown as reference number  690 . The resin material that is used for this resin mold usually has a high coefficient of thermal expansion. Consequently, in the process of forming the resin mold, relatively great thermal stress acts on the leads  560  and  570 ;  660  and  670 . Thereby undesirable stress is applied to the LED chip itself and to the connecting component between the LED chip and the leads and can be a cause of breakage of the LED chip or a poor connection.  
         SUMMARY OF THE INVENTION  
         [0008]    Consequently, the object of this invention is to provide a light-emitting diode and a method for its manufacture for preventing undesirable stress from being applied on the LED chip during the manufacturing process of the light-emitting diode, for assuring a reliability of function and for increasing the manufacturing yield.  
           [0009]    This invention provides a light-emitting diode which is a light-emitting diode with a connecting portion for connecting between the light-emitting diode chip (LED chip) and the external circuit characterized in that it has a cup material made of an insulating material [that] for housing the said light-emitting diode chip and in that paired electrical conducting traces are printed and formed on the surface of said cup component by an MID means (Molded Interconnect Device), in that the said light-emitting diode chip is mounted on the said cup, so that it is connected to the said paired electrical conducting traces and in that the said connection part is constructed so that there is electrical conduction with the said connection part due to the fact that it is connected to the said paired electrical conducting traces.  
           [0010]    Preferably, it also has other electronic or electrical components that are placed along the said surface of the said cup component or a circuit that contains said other electronic or electrical components.  
           [0011]    Preferably, said other electronic or electrical components contain a protective element that electrically protects the said light-emitting diode chip and said protective element is constructed so that there is electrical conduction with the said paired electrical conducting traces.  
           [0012]    Preferably, said other electronic or electrical components contain at least a light-emission monitoring element that can sense light emission from the said light-emitting diode chip or a heat-generation monitor element that can sense the temperature in the vicinity of the said chip component and in that the said light-emission monitoring element or the said heat-emission monitoring element is connected electrically to the other electrical conducting traces that is formed by the MID method on the said surface so that it is independent from the said paired electrical conducting traces.  
           [0013]    Preferably, it has another connecting component that is in electrical connection with the said other electrical conducting traces and that is used for the purpose of connecting the said other electrical conducting traces to the external circuit.  
           [0014]    Preferably, said connection part is constructed so that there is a pair of leads and so that said pair of leads and the said paired electrical conducting traces are connected electrically.  
           [0015]    Preferably, said cup component has an engaging portion to be engaged with said pair of leads.  
           [0016]    Preferably, said respective pair of leads contain an extension component that extends to the vicinity of the said light-emitting diode chip.  
           [0017]    Preferably, said cup component is made of resin or a ceramic material.  
           [0018]    Preferably, said connecting portion is constructed so that it contains a portion of the said paired electrical conducting traces.  
           [0019]    Preferably, the said cup component contains an engaging portion to be engaged with the component in which the said light-emitting diode is held.  
           [0020]    Preferably, several of the said light-emitting diode chips are installed and in that three or more electrical conducting traces are installed in place of the said pair of electrical conducting traces, so that they are connected with a pair of electrodes that each has.  
           [0021]    This invention provides a method of manufacturing light-emitting diodes comprise a process of forming at least one pair of electrical conducting traces by the MID means on the surface of the cup material which is comprised of an insulating material having a cup structure, a process of monitoring the light-emitting diode chip on the bottom surface of said cup structure to produce a secondary assembly and a process of assembling the said secondary assembly together with the other components to complete the light-emitting diode.  
           [0022]    Preferably, the process of assembling with said other parts includes a process in which the said secondary assembly is assembled together with the lead component and in which the parts are electrically connected.  
           [0023]    Preferably, the process of assembly with the said other parts includes a process in which a resin mold is formed so that the parts are covered by resin from the outside of the said secondary assembly.  
           [0024]    The light-emitting diode of this invention has a cup component that is comprised of an insulator such as resin or a ceramic material. The cup component has electrical conducting traces formed by means of an MID method so that they extend along its surface. The LED chip is electrically and mechanically coupled by conventional technique to these electrical conducting traces. Specifically, by mounting the LED chip on the cup component, the assembly can be handled taking the cup component as a unit. This is extremely advantageous for the working tests that are performed after mounting the LED chip. Further, the cup component can provide a reflecting surface as a single entity that reflects the emitted light from the LED chip so that it is directed upward.  
           [0025]    In one mode of embodiment, the cup component is engaged mechanically to a pair of metal leads that extend to the exterior and is connected electrically to these leads by a known device such as a solder connection. This is an advantage in the manufacturing assembly process. As in the conventional examples, the LED chip is molded and affixed with the cup component by means of resin. However, the pair of electrodes of the LED chip are mounted on a cup material with a relatively low thermal expansion coefficient and are therefore not greatly subjected to the effects of thermal stress in the process of resin molding. Specifically, by making the coefficient of thermal expansion of the cup component less than that of the resin material for molding and greater than that of the LED chip, the effects of thermal stress on the LED chip are kept to a minimum and a large stress effect does not occur on the connecting portion between the electrical conducting traces and the leads of the cup component.  
           [0026]    In another mode of embodiment, a structure corresponding to metal leads can be formed as a single entity with the cup material. Specifically, by this mode, the cup portion contains a linking structure with the circuit board to which the light-emitting diode is connected.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]    [0027]FIG. 1 is a cross-sectional view that shows the internal structure of a conventional light-emitting diode and (a) and (b) are figures that illustrate the first and second conventional technologies.  
         [0028]    [0028]FIG. 2 is a figure that shows the structure for the light-emitting diode which is the first desirable mode of embodiment of this invention. (a) is an perspective view that shows the structure in the vicinity of the LED chip, (b) is a plane view of it and (c) is a cross-sectional view in the position along line A-A in (b).  
         [0029]    [0029]FIG. 3 is a figure that shows the structure for the light-emitting diode which is the second desirable mode of embodiment of this invention. (a) is an perspective view that shows the structure in the vicinity of the LED chip, (b) is a plane view of it and (c) is a cross-sectional view in the position along line A-A in (b).  
         [0030]    [0030]FIG. 4 is a figure that shows the structure for the light-emifting diode which is the third desirable mode of embodiment of this invention. (a) is an perspective view that shows an outline of the structure and (b) is a figure that shows a cross section.  
         [0031]    [0031]FIG. 5 is a figure that shows the structure for the light-emitting diode which is the fourth desirable mode of embodiment of this invention. (a) is an perspective view that shows the structure in the vicinity of the LED chip and (b) is an perspective view that shows the state before assembly of the leads in which the cup component is seen from the bottom side.  
         [0032]    [0032]FIG. 6 is a figure that shows the structure for the light-emitting diode which is the fourth desirable mode of embodiment of this invention. (a) and (b) are cross-sectional views for illustrating the assembly of the cup component and the leads over time. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]    The following definitions are presented to provide a better understanding of the Figures in conjunction with the following detailed description of the invention.  
                                         Definition of symbols                                40; 140; 240; 340   LED chips       11; 111; 211; 311   cup components       31, 33, 35; 131, 133, 135; 231, 233,   first electrical conducting traces       235; 331, 333       32, 34, 36; 132, 134, 136; 232, 234,   second electrical conducting trace       236; 332, 334       150   protective element       11, 111, 211, 311   first lead       12, 112, 212, 312   second lead       323, 324   extended part (small projection)                  
 
         [0034]    We shall now present a detailed description of a light-emitting diode that is a desirable mode of embodiment of this invention and of the method for its manufacture by reference to the appended figures.  
         [0035]    [0035]FIG. 2 is a figure that shows the structure of a light-emitting diode that is the first desirable mode of embodiment of this invention. A light-emitting diode and a method for its manufacture is described in which, during manufacture of the light-emitting diode, the application of undesirable stress on the LED chip is prevented and reliability of function is assured. Generally, the light-emitting diode contains the cup portion  11  that is comprised of resin or a ceramic material, the LED chip  40  and a secondary assembly comprised of the leads  21  and  22  and is manufactured by molding and sealing them with resin. The paired conducting traces  31 ,  33 ,  35 ; and  32 ,  34 ,  36  are formed by an MID method on the surface of cup component  11 . The LED chip  40  is positioned at end parts  71  and  72  of electrical conducting traces  31  and  32 , and is mounted on cup component  11  and leads  21  and  22  are connected to electrical conducting traces  35  and  36  in another position.  
         [0036]    In FIG. 2, (a) is an perspective view that shows the structure in the vicinity of the LED chip, and (b) is a plane view of it and (c) is a cross-sectional view in the position along line A-A in (b).  
         [0037]    The light-emitting diode of the first preferable mode of embodiment is similar on its basic structure to that of the conventional technology shown FIG. 1( b ) and ( c ) in that it has the pair of leads  21  and  22  and the LED chip  40  that is connected electrically to these leads. Moreover, although not shown in the figure, it contains molded resin that is installed so as to surround the vicinity of the tips of the leads shown in FIG. 2( a ) to ( c ). The molded resin can be made in a shape of a bullet so that it ordinarily has a lens effect on the upper side.  
         [0038]    One point of difference of the light-emitting diode of this invention from the conventional technology is the presence of the cup component  11 . The cup component  11  is formed by a material such as resin or a ceramic material and is essentially a disk-shaped component. It has the reflecting surface  12  that forms a conical depression on the upper side and the bottom part  13 . It also has the paired steps  14  and  15  in the lateral end positions facing the bottom side. Moreover, the cup component  11  has the electrical conducting traces  31 ,  33  and  35 ; and  32 ,  34 , and  36  that are printed by an MID method along its surfaces. The electrical conducting traces  31 ,  33  and  35 ; and  32 ,  34  and  36  extend in directions facing each other on the reflecting surface  12  from the bottom  31  and bend at the lateral faces from the upper side, reaching the steps  14  and  15 .  
         [0039]    As shown in the figure, the “flip-chip” mounted type of LED chip  40  is connected by a known means such as soldering to the ends  71  and  72  of the pair of electrical conducting traces  31  and  32  on the bottom part  13 . By this means, the LED chip  40  is affixed mechanically so that the emitted light is directed upward by the reflecting surface  12  and so that it is enclosed by the reflecting surface  12 . When LED chip  40  is mounted on cup component  11  before the leads  21  and  22  and the cup component are connected as described subsequently, LED chip  40  can be handled by taking cup component  11  as a unit and operations are facilitated during working tests.  
         [0040]    The tips of the pair of leads  21  and  22 , which are electrically connected to LED chip  40 , are placed so that they are linked to steps  14  and  15  of cup component  11  and are connected in this position by a means such as soldering to electrical conducting traces  35  and  36 . In the figure, a structure is shown in which leads  21  and  22  are positioned at steps  14  and  15 . For convenience in the assembly operation, a structure can be produced in which leads  21  and  22  are temporarily held in cup component  11  by a mechanical linkage relationship.  
         [0041]    LED chip  40  and the secondary assemblies of cup component  11  and the pair of leads  21  and  22  that have been assembled in this way are subsequently affixed and protected by the resin mold, which is not shown in the figure, so that leads  21  and  22  protrude to the outside. The effect of thermal stress on LED chip  40  that is produced at this time is greatly reduced by the presence of cup component  11 . Further, by forming cup component  11  with a material having a higher coefficient of thermal expansion than that of LED chip  40 , there is no deleterious effect due to heat on the connection part of leads  21  and  22  and cup component  11 .  
         [0042]    By forming cup component  11  with a material of relatively high heat conductivity, the operation of the light-emitting diode can be further stabilized. In particular, when cup component  11  is formed by molding of resin, there is the advantage that the shape of reflecting surface  12  can easily be processed to the required shape.  
         [0043]    [0043]FIG. 3 is a figure that shows the structure for the light-emitting diode that is the second desirable mode of embodiment of this invention. (a) is an perspective view that shows the structure in the vicinity of the LED chip, (b) is a plane view thereof and (c) is a cross-sectional view in the position along line A-A in (b). The point of difference of the second desirable mode of embodiment from the first desirable mode of embodiment is primarily the point that a protective element  150 , such as a diode for the purpose of protection against static electricity, is installed. The structural elements that do not differ from those of the first mode of embodiment are designated by adding 100 to the reference numbers and explanations of these elements are omitted.  
         [0044]    As shown in FIG. 3, cup component  111  also has the additional electrical conducting traces  137  and  138  that branch from electrical conducting traces  131  and  132  and that extend along the annular top surface  118  of the apex end. These electrical conducting traces  131  and  132  are also formed by an MID method. They are used for the purpose of connecting protective element  150  such as a diode. The protective element is installed for the purpose of preventing LED chip  140  from breaking as a result of the application of excessive voltage in the reverse direction of the LED chip  140 . By this means, a higher working reliability of the LED chip  140  is assured. Protective element  150  can also be mounted in parallel with the process of mounting LED chip  140 .  
         [0045]    In this mode of operation, only an element protecting against static electricity is indicated as an example of an additional element. However, other elements and circuits in addition to the element protecting against static electricity may be installed. Examples of these elements and circuits include light-emission monitoring element that can sense light emission from the LED chip, heat-generation monitoring elements that can sense the temperature in the vicinity of the cup material, current-limiting resistors, circuits that contain these resistors or drive circuits. When these elements and circuits are installed, and, in particular, when electrical conducting traces that are independent from the electrical conducting traces for the LED chip are necessary, such circuitry can be formed on the cup component by an MID method. Moreover, such electrical conducting traces can be connected electrically to connecting components such the leads that are additionally installed for the purpose of connection with outside circuits.  
         [0046]    [0046]FIG. 4 is a figure that shows the structure of a light-emitting diode which a third desirable mode of embodiment of this invention. (a) is an perspective view that shows an outline of the structure and (b) is a figure that shows a cross-sectional view. The light-emitting diodes based on the third desirable mode of embodiment differ from those of the said modes of embodiment in that leads are not necessary. Similarly, the structural elements that are used are indicated by adding  200  to the reference numbers used in the first mode of embodiment.  
         [0047]    The light-emitting diode  200  based on this desirable mode of embodiment has the cup component  211  in which the paired electrical conducting traces  231 ,  233  and  235  as well as  232 ,  234  and  236  are formed, the LED chip  240  that is mounted in the cup component  211 , and the resin mold  290  that is shown provisionally by the broken line. LED chip  240  is mounted on the bottom part  213  on the inner side of the reflecting surface  212 .  
         [0048]    The characteristic point in this mode of embodiment is that cup component  211  has the projecting structures  214  and  215  as a single entity. As shown in FIG. 4( b ), projecting structures  214  and  215  have dimensions that project and extend from resin mold  290 . As shown in the figure, the paired electrical conducting traces  231 ,  233  and  235  as well as  232 ,  234  and  236  that are printed and formed by the MID method so that they are connected to the LED chip extend along the outer lateral surfaces of these projecting structures  214  and  215 .  
         [0049]    Projecting structures  214  and  215  are used when light-emitting diode  200  is connected to circuit boards. Specifically, the pair of structures  214  and  215  are placed to that they pass through throughholes (not shown in the figure) that pass through the circuit board. At this time, the electrical conducting traces  235  and  236  in the vicinity of the tips of projecting structures  214  and  215  are connected by a means such as soldering with the circuit pattern on the circuit board. In order to facilitate the connecting operation with the circuit board, an additional linking structure for provisionally holding light-emitting diode  200  to the circuit board can be formed on projecting structures  214  and  215 .  
         [0050]    [0050]FIG. 5 and FIG. 6 show a fourth desirable mode of embodiment of this invention. FIG. 5( a ) is an perspective view that shows the structure in the vicinity of the LED chip and (b) is an perspective view that shows the state before assembly of the lead when the cup component is viewed from the bottom side. FIGS.  6 ( a ) and ( b ) are cross-sectional views for the purpose of illustrating the step-by-step process of assembly of the cup component and the leads.  
         [0051]    [0051]FIG. 5( a ) is a figure that is similar to FIG. 1( a ) and is a partial view of the secondary assembly from which the resin mold is omitted. In this mode of embodiment as well, the following are included: the cup component  311 , the LED chip  340  which is situated on its inner side and the pair of leads  321  and  322  which are assembled in cup component  311 . Because the basic structure is similar to that of the first mode of embodiment, for components that have a similar function,  300  is added to the reference numbers and an explanation is omitted. The characteristic point of this mode of embodiment is that it is constituted so that the connection of the pair of leads  321  and  322  with electrical conducting traces  323 ,  331 ;  324 ,  332  is produced at a position close to LED chip  340 .  
         [0052]    As can be understood from FIG. 5( b ) and FIG. 6( a ), the pair of rectangular holes  301  and  302  are formed in the bottom surface of cup component  311 . These rectangular holes  301  and  302  are made in dimensions such that they can accommodate leads  321  and  322 . Electrical conducting traces  331  and  332  are formed by an MID method inside rectangular holes  301  and  302  along the partition  319  that separates rectangular holes  301  and  302 . The small throughholes  305  and  306  are formed so that they are in communication with the rectangular holes  301  and  302  and so that they pass through to the bottom part  313  on which LED chip  340  is installed. As described subsequently, they are constructed so that they accommodate the small projections  323  and  324  that are formed in the tips of leads  321  and  322 . Electrical conducting traces  331  and  332  are extended in a linear pattern along the partition  319  into the small throughholes  305  and  306 . The electrical conducting traces  371  and  372  for mounting LED chip  340  are formed by an MID method on the bottom part  313  and electrical conducting traces  331  and  332  are constituted so that they are bonded with them.  
         [0053]    Leads  321  and  322  have base parts  321   a  and  322   a  that form a plate shape and connecting parts  321   b  and  322   b  that extend from base parts  321   a  and  322   a  and are connected to the circuit board. Small projections  323  and  324  are established in the end parts of the inner sides of the upper lateral margins of base parts  321   a  and  322   a.  As shown in FIG. 5( b ) or FIGS.  6 ( a ) and (b), leads  321  and  322  are inserted into rectangular holes  301  and  302  from the bottom side of cup component  311 . At this time, the rectangular holes may be made in dimensions whereby leads  321  and  322  can be fitted tightly into these holes and held mechanically. When they are inserted as described above, small projections  323  and  324  can be engaged with small throughholes  305  and  306  and their upper ends reach approximately the position of the height of bottom part  313 . Following this insertion, leads  321  and  322  can be connected by various known methods such as soldering with the electrical conducting traces  331  and  332  in a position on the inside margin of the base parts  321   a  and  322   a  and with electrical conducting traces  371  and  372  in the position of small projections  323  and  324 .  
         [0054]    As in the modes of embodiment described above, the assembly of leads  321  and  322  may be performed after LED chip  340  has been mounted on cup component  311  in order to facilitate the handling of LED chip  340  for performing operating tests. However, the mounting of LED chip  340  on cup component  311  can also be performed at the same time as leads  321  and  322  with electrical conducting traces  323 ,  331 ;  324 ,  332 . As in the mode of embodiment described above, the secondary assemblies (see FIG. 5( a ) or FIG. 6( b )), which are completed by assembling cup component  311  with LED chip  340  and with leads  321  and  322 , are further resin molded from the outer side and the light-emitting diode is completed by this means.  
         [0055]    The advantage of the light-emitting diode based on the fourth desirable mode of embodiment is that superior heat-radiating properties are obtained. Specifically, the heat that is generated in the position of LED chip  340  during operation is readily transmitted to leads  321  and  322 , by which means the heat can be radiated to the exterior by means of the leads. Consequently, even when the completed light-emitting diode has been used for a long time, its light-emitting properties do not readily deteriorate.  
         [0056]    Above, we have described desirable modes of embodiment of this invention. However, these are strictly illustrations and modifications and changes can be made by persons skilled in the art. For example, the type of mounting of the LED is not limited to the “flip-chip” type and it may be a “flop-chip” type or another type. Further, in the various modes of embodiment, we have described the case of one LED chip that is mounted on a single cup component. However, there may also be a structure in which several LED chips are mounted in a single cup. In addition, several leads that are connected to a single cup component, or, as in the third mode of embodiment, several structures that connect to the circuit board and extend from the cup component can be formed.