Patent Application
20120061703
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2010-125746, filed on Jun. 1, 2010, the entire contents of which are incorporated herein by reference.
For a light emitting device such as a light emitting diode (LED), adopted is a structure in which: a LED chip mounted on a lead is housed in a recess structure of a resin package; and the LED chip is sealed with a phosphor-containing resin in a covering manner. Moreover, from the view point of reducing the size of the package, adopted is a structure in which: a LED chip is mounted on a lead; and the periphery of the LED chip is sealed with a phosphor-containing resin in the covering manner. Furthermore, for the resin package having the recess structure as described above, adopted is a structure in which: a LED chip in the recess structure is sealed with a transparent resin; and the recess structure is capped with a phosphor-containing cap.
However, in the structures in which the LED chip is sealed with the phosphor-containing resin, the distance that light travels through the phosphor-containing resin differs between a right upward direction and an oblique direction in an optical path along which light emitted from the LED chip travels through the package and is emitted to the outside. This difference causes difference in chromaticity among center portions and circumferential portions of the package. Although such difference is less likely to occur in the structure in which the recess structure is capped with the phosphor-containing cap, this structure requires additional steps of forming the cap, and of capping the recess structure with the cap.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.
Various connections between elements are hereinafter described. It is noted that these connections are illustrated in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect.
Embodiments of the present invention will be explained with reference to the drawings as next described, wherein like reference numerals designate identical or corresponding parts throughout the several views.
Embodiments of the present invention will be described based on the drawings.
Note that the drawings are schematic or conceptual. Relationships between the thicknesses and the widths of parts, ratios between the sizes of parts, and the like may differ from actual ones. Moreover, the same part may be illustrated in different dimension and ratio from one drawing to another.
Furthermore, similar components which have been already described in the previous drawings will be denoted with the same reference numerals, and detailed description thereof will be omitted as appropriate.
In addition, an XYZ-orthogonal coordinate system is used in this specification for convenience of description. Among directions parallel to upper surfaces of a first lead portion 11 and a second lead portion 12, a direction heading from the first lead portion 11 to the second lead portion 12 is referred to as a +X direction. Among directions perpendicular to the upper surfaces of the first lead portion 11 and the second lead portion 12, a direction heading upward, that is to say, a direction in which a later-described light emitting element 14 is mounted in a view from the first and second lead portions is referred to as a +Z direction. Among directions orthogonal to both the +X direction and the +Z direction, one direction is referred to as a +Y direction. Note that directions opposite to the +X direction, the +Y direction, and the +Z direction are referred to as a −X direction, a −Y direction, and a −Z direction, respectively. Moreover, for example, the “+X direction” and the “−X direction” may be collectively referred to as the “X direction.”
In order to make the drawings easy to see, phosphor particles are illustrated in larger size and smaller number than an actual case. Moreover, the phosphor is omitted in the drawings other than
As shown in
The lead 10 includes a first lead portion (first base portion) 11 and a second lead portion (second base portion) 12. The first lead portion 11 and the second lead portion 12 each have a flat plate shape, and are disposed on the same plane with a space therebetween. The first lead portion 11 and the second lead portion 12 are made of the same electrically conductive material. For example, the first lead portion 11 and the second lead portion 12 are each a copper plate with silver plating layers formed respectively on upper and lower surfaces thereof. Note that no silver plating layer is formed on edge surfaces of the first lead portion 11 or the second lead portion 12, and the copper plates are exposed therefrom.
The first lead portion 11 is provided with one base portion 11a which has a rectangular shape when viewed in the Z direction. Four hanging pins 11b, 11c, 11d, 11e extend out from the base portion 11a. The hanging pin 11b extends out in the +Y direction from a portion at the center, in the X direction, of an edge of the base portion 11a facing in the +Y direction. The hanging pin 11c extends out in the −Y direction from a portion at the center, in the X direction, of an edge of the base portion 11a facing in the −Y direction. As described, the hanging pins 11b to 11e extend out from three different sides of the base portion 11a. The positions of the hanging pins 11b, 11c in the X direction are the same. The hanging pins 11d, lie extend out in the −X direction respectively from both end portions of an edge of the base portion 11a facing in the −X direction. Since the hanging pins 11b to 11e are provided at intervals on the side surfaces 11s of the first lead portion 11, the recess portion DP is formed between each adjacent two of the hanging pins 11b to 11e.
The second lead portion 12 is shorter than the first lead portion 11 in the length in the X direction, while the second lead portion 12 is equal to the first lead portion 11 in the length in the Y direction. The second lead portion 12 is provided with one base portion 12a which has a rectangular shape when viewed in the Z direction. Four hanging pins 12b, 12c, 12d, 12e extend out from the base portion 12a. The hanging pin 12b extends out in the +Y direction from an end portion, on the −X direction side, of an edge of the base portion 12a facing in the +Y direction. The hanging pin 12c extends out in the −Y direction from an end portion, on the −X direction side, of an edge of the base portion 12a facing in the −Y direction. The hanging pins 12d, 12e extend out in the +X direction respectively from both end portions of an edge of the base portion 12a facing in the +X direction. As described, the hanging pins 12b to 12e extend out from three different sides of the base portion 12a. The width of each of the hanging pins 11d, 11e of the first lead portion 11 may be equal to the width of each of the hanging pins 12d, 12e of the second lead portion 12, or may be different. Note that, if the width of each of the hanging pins 11d, 11e of the first lead portion 11 is made different from the width of each of the hanging pins 12d, 12e of the second lead portion 12, an anode and a cathode can be distinguished from each other easily. Since the hanging pins 12b to 12e are provided at intervals on the side surfaces 11s of the second lead portion 12, the recess portion DP is formed between each adjacent two of the hanging pins 12b to 12e.
A protruding portion 11g is formed on a lower surface 11f of the first lead portion 11, and is located in a center portion of the base portion 11a in the X direction. Accordingly, the first lead portion 11 has two values in thickness. Specifically, the center portion of the base portion 11a in the X direction, that is to say, the portion where the protruding portion 11g is formed, is relatively large in thickness, while both end portions of the base portion 11a in the X direction and the hanging pins 11b to 11e are relatively small in thickness. In
The protruding portions 11g, 12g are formed in regions located away from the opposed edges of the first lead portion 11 and the second lead portion 12, respectively. Regions including these edges are the thin plate portions 11t, 12t. An upper surface 11h of the first lead portion 11 and an upper surface 12h of the second lead portion 12 are on the same plane. A lower surface of the protruding portion 11g of the first lead portion 11 and a lower surface of the protruding portion 12g of the second lead portion 12 are on the same plane. The upper surface 11h of the first lead portion 11 and the upper surface 12h of the second lead portion 12 are the first main surface s1. The positions of upper surfaces of the hanging pins in the Z direction coincide with the positions of the upper surfaces of the first lead portion 11 and the second lead portion 12. Thus, the hanging pins are disposed on the same XY plane.
On the upper surface 11h of the first lead portion 11, a die-mount material 13 is applied to a portion of a region corresponding to the base portion 11a. In this embodiment, the die-mount material 13 is electrically conductive. The die-mount material 13 is made of, for example, silver paste, solder, eutectic solder, or the like.
The light emitting element 14 is provided on the die-mount material 13. Specifically, the light emitting element 14 is fixed to the first lead portion 11 with the die-mount material 13, and the light emitting element 14 is thus mounted on the first lead portion 11. Moreover, a back surface of the light emitting element 14 is conductive with the first lead portion 11 via the die-mount material 13. The light emitting element 14 is, for example, an element formed by stacking semiconductor layers made of gallium nitride (GaN) and the like on a sapphire substrate. The light emitting element 14 has, for example, a rectangular solid shape, and a terminal 14b is provided on an upper surface thereof. The light emitting element 14 emits, for example, blue light when a voltage is supplied between the terminal 14b and the back surface of the light emitting element 14.
An end of a wire 16 is bonded to the terminal 14b of the light emitting element 14. The wire 16 is lead out in the +Z direction from the terminal 14b, and is curved in a direction between the +X direction and the −Z direction. The other end of the wire 16 is bonded to the upper surface 12h of the second lead portion 12. Thus, the terminal 14b is connected to the second lead portion 12 via the wire 16. The wire 16 is made of metal such as gold or aluminum.
The light emitting device 1 is provided with the first resin body 171. The first resin body 171 is made of a transparent resin (translucent resin) such as a silicone resin. Note that “transparent” also includes semitransparent. The external shape of the first resin body 171 is a rectangular solid, and is provided to cover the light emitting element 14, the wire 16, the surface 11h of the first lead portion 11, and the surface 12h of the second lead portion 12 on the first main surface s1 side of the first lead portion 11 and the second lead portion 12. In addition, the first resin body 171 is embedded in the recess portions DP provided in the side surfaces 11s of the first lead portion 11 and the side surfaces 12s of the second lead portion 12.
Moreover, the light emitting device 1 is provided with the second resin body 172. The second resin body 172 is made of a resin such as a silicone resin including the phosphor leighthe second resin body 172 is provided to cover the exterior of the first resin body 171 from the first main surface s1 side to at least a position of the lowermost end of the recess portions DP in a direction orthogonal to the first main surface s1. In this respect, the position of the lowermost end means a position which is farthest from the first main surface s1 among positions on each recess portion DP in the Z direction. In this specific example, the positions on the recess portions DP in the Z direction spread from the first main surface s1 to a second main surface s2. Accordingly, the position of the lowermost end is the position of the second main surface s2.
In this specific example, the second resin body 172 covers a top surface 171a and side surfaces 171b of the first resin body 171, the side surfaces 11s of the first lead portion 11, and the side surfaces 12s of the second lead portion 12, as well as reaches the position of the second main surface s2.
To be more specific, in the lower surface 11f of the first lead portion 11, the lower surface of the protrusion 11g is exposed from a lower surface of the first resin body 171. Meanwhile, the entire upper surface 11h of the first lead portion 11, the regions other than the protruding portion 11g in the lower surface 11f, the entire upper surface 12h of the second lead portion 12, and regions other than the protruding portion 12g in the lower surface 12f are covered with the first resin body 171. In addition, the top surface 171a and the side surfaces 171b of the first resin body 171, front end surfaces of the hanging pins 11b to 11e, and front end surfaces of the hanging pins 12b to 12e are covered with the second resin body 172. In the light emitting device 1, the lower surfaces of the protruding portions 11g, 12g exposed from the lower surface of the first resin body 171 serve as external electrode pads.
In this respect, the second resin body 172 includes a large number of particles of the phosphor leighthe phosphor 18 is granular, absorbs light emitted from the light emitting element 14, and emits light with a wavelength longer than the absorbed light. For example, the phosphor 18 absorbs part of the blue light emitted from the light emitting element 14, and emits yellow light. Thus, the blue light transmitting through the second resin body 172 and the yellow light resulting from the wavelength conversion by the phosphor 18 are combined, and white light is obtained. Note that the wavelength of the light emitted from the light emitting element 14 and the wavelength of the light resulting from the conversion by the phosphor 18 are not limited to those described above.
The second resin body 172 has a uniform thickness. In other words, the thickness of a portion of the second resin body 172 covering the top surface 171a of the first resin body 171 in the Z direction is equal to the thickness of portions of the second resin body 172 covering the side surfaces 171b of the first resin body 171 in the X direction and the Y direction.
In the light emitting device 1 according to this embodiment, since the second resin body 172 has the uniform thickness as described above, the difference in the distance that the light travels through the second resin body 172 becomes smaller among various angles at which the light is radially emitted from the light emitting device 14. Thus, variation in the wavelength conversion by the phosphor 18 is suppressed among the various angles at which the light is emitted radially, and dependency of the chromaticity of the emitted light on its angle is suppressed.
Moreover, as shown in
In addition, as shown in
In addition, since the side surfaces 11s of the first lead portion 11 and the side surfaces 12s of the second lead portion 12, that is to say, the front end surfaces of the hanging pins 11b to 11e, 12b to 12e are covered with the second resin body 172, corrosion of the first lead portion 11 and the second lead portion 12 which occurs from these surfaces is prevented.
Next, a method of manufacturing the light emitting device according to this embodiment will be described.
Firstly, as shown in
Subsequently, the electrically conductive sheet 21 covered with the masks 22a, 22b is subjected to wet etching by being immersed in an etchant. Thus, portions of the electrically conductive sheet 21 which are in the opening portions 22c are etched away and selectively removed. At this time, the etching amount is controlled by, for example, adjusting the immersing time. Thus, the etching is stopped before the etching from each of the upper surface and the lower surface of the electrically conductive sheet 21 penetrates the electrically conductive sheet 21 singly. Thereby, half etching is performed from both the upper surface and the lower surface. Note that portions etched from both the upper surface and the lower surface penetrate the electrically conductive sheet 21. Thereafter, the masks 22a and 22b are removed.
Subsequently, as shown in
In other words, although the first lead portion 11 and the second lead portion 12 are disposed away from each other in each of the element regions P, the first lead portion 11 belonging to any element region P is connected to the second lead portion 12 belonging to an adjacent element region P in −X direction. An opening portion 23a having a square-on-rectangle shape which faces in the +X direction is formed between each two adjacent frames. Moreover, the first lead portions 11 belonging to each two adjacent element regions P in the Y direction are connected to each other via a bridge 23b. Similarly, the second lead portions 12 belonging to each two adjacent element regions P in the Y direction are connected to each other via a bridge 23c. Accordingly, four conductive members extend out in three directions from the base portion 11a of each first lead portion 11 and from the base portion 12a of each second lead portion 12. Spaces provided in the openings 23a and spaces between bridges 23b, 23c serve as the recess portions DP provided in the side surfaces of the leads 10.
Thereafter, the lead frame 23 is half-etched from the lower surface, and the protruding portions 11g, 12g (see
Next, as shown in
Next, as shown in
Next, as shown in
Next, as shown in
Thereafter, as shown in
Next, as shown in
Portions of the lead frame 23 and the transparent resin plate 29a which are disposed in dicing regions D1 are removed by the dicing. As a result, portions of the lead frame 23 and the transparent resin plate 29a which are disposed in the element regions P are formed into individual pieces, and thus the first resin element bodies 171, the first lead portions 11, and the second lead portions 12 as shown in
After the individual pieces are formed by the dicing, the dicing sheet 102 is removed, and another dicing sheet 120 (see
The dicing sheet is replaced as follows. Firstly, the top surfaces of the first resin bodies 171 are attached to an adhesive sheet or a workbench with adhesiveness, and the first resin bodies 171 are fixed thereto. Then, the dicing sheet 102 attached to the first lead portions 11 and the second lead portions 12 is peeled off. Thereafter, the new dicing sheet 120 is attached to the first lead portions 11 and the second lead portions 12. Subsequently, the adhesive sheet or the workbench attached to the top surfaces of the first resin bodies 171 is peeled off.
Subsequently, as shown in
Next, as shown in
Next, as shown in
Subsequently, as shown in
How the phosphor-containing resin plate 29b is removed with the blade 114 will be described.
The phosphor-containing resin plate 29b is cut with the blade 114 at positions between the adjacent first resin bodies 171. The width d of the blade 114 is smaller than the width D1 of the phosphor-containing resin plate 29b between the adjacent first resin bodies 171. The width D2 of the cuts formed in the phosphor-containing resin plate 29b is set in accordance with the width d of the blade 114.
The width t2 of the remaining phosphor-containing resin plate 29b is equal to the thickness t1 of the phosphor-containing resin plate 29b provided on the top surfaces 171a of the first resin bodies 171.
In other words, when the phosphor-containing resin plate 29b is divided with the blade 114, the second resin bodies 172 are formed into such individual pieces that the thickness thereof on the top surface 171a side of the first resin body 171 is equal to the thickness thereof on the side surface 171b side of the first resin body 171. In order to form the second resin bodies 172 as described above by cutting the phosphor-containing resin plate 29b with the blade 114, the width D1 between the adjacent first resin bodies 171 is set as follows:
D1=2×t2+D2
where t2 denotes the width of the portion of the second resin body 172 remaining on the side surface 171b of each of the first resin bodies 171, and d2 denotes the width of the cuts formed with the blade 114 to divide the phosphor-containing resin plate 29b.
According to the method of manufacturing the light emitting device 1 of this embodiment, the width D1 between the adjacent first resin bodies 171 is set at the value described above. Then, the cutting is performed with the center of the width D1 and the center of the blade 114 aligned with each other. Thus, simultaneously with the cutting of the phosphor-containing resin plate 29b with the blade 114, the second resin bodies 172 with the uniform thickness are formed. The second resin bodies 172 thus formed each cover the outside of the corresponding first resin body 171 from the first main surface s1 side to at least the position of the lowermost end of the recess portions DP.
In each of the light emitting devices 1 thus manufactured, the difference in the distance that the light travels through the second resin body 172 becomes smaller among various angles at which the light is radially emitted from the light emitting device 14. Thus, variation in the wavelength conversion by the phosphor 18 is suppressed among the various angles at which the light is emitted radially, and dependency of the chromaticity of the emitted light on its angle is suppressed.
Moreover, since the light emitting device 1 is covered with the second resin body 172 to the position of the lowermost end of the recess portions DP, light leaking to the outside from the recess portions DP also travels through the second resin body 172. Thus, the light leaking from the recess portions DP are also subjected to the wavelength conversion by the phosphor 18.
In addition, since the side surfaces 171b of the first resin body, the side surfaces 11s of the first lead portion 11, and the side surfaces 12s of the second lead portion 12 are covered with the second resin body 172, light leaking from the space between the first lead portion 11 and the second lead portion 12 also travels through the second resin body 172. Thus, the light leaking from the space SL between the first lead portion 11 and the second lead portion 12 are also subjected to the wavelength conversion by the phosphor 18. Moreover, since the side surfaces 11s of the first lead portion 11 and the side surfaces 12s of the second lead portion 12, that is to say, the front end surfaces of the hanging pins 11b to 11e, 12b to 12e are covered with the second resin body 172, corrosion of the first lead portion 11 and the second lead portion 12 which occurs from these surfaces is prevented.
Next, a first modification of the first embodiment will be described.
This modification is a modification of the method of forming the lead frame.
Specifically, this modification is different from the first embodiment described above in the method of forming the lead frame shown in
Firstly, as shown in
Next, as shown in
Subsequently, as shown in
Thereafter, as shown in
Next, as shown in
Thereafter, as shown in
Next, descriptions will be provided for a second modification of the first embodiment.
This modification is a modification of the method of manufacturing the light emitting device.
In this modification, molds 130, 140 are used to form the first resin bodies 171.
In this respect, steps up to the mounting of light emitting elements 14 on first lead portions 11 and second lead portions 12, and the connection of the wires 16 to the first lead portions 11 and the second lead portions 12 are the same as the steps illustrated in
Next, a lead frame 23 on which the light emitting elements 14 are mounted is attached to the lower surface of a dicing sheet 102 in a manner that the light emitting elements 14 face downward. Then, as shown in
Thereafter, heat treatment (mold curing) is performed while the upper surface of the lead frame 23 is pressed against the transparent resin 26a, and thus the transparent resin 26a is cured. Then, as shown in
In this respect, the lead frame 23 is cut in a following way. Firstly, the top surfaces of the first resin bodies 171 are attached to an adhesive sheet or a workbench with adhesiveness, and the first resin bodies 171 are fixed thereto. Then, the dicing sheet 102 is peeled off. In this state, the lead frame 23 which is exposed is cut along the external shapes of the first resin bodies 171, and thus the first lead portions 11 and the second lead portions 12 are formed. Thereafter, the new dicing sheet 120 is attached to the first lead portions 11 and the second lead portions 12. Subsequently, the adhesive sheet or the workbench attached to the top surfaces of the first resin bodies 171 is peeled off.
Subsequently, the mold 140 is prepared as shown in
Next, the first lead portions 11 and the second lead portions 12 on which the dicing sheet 120 is attached are placed in a manner that the first resin bodies 171 face downward. Subsequently, the dicing sheet 120 is pressed on the mold 140. On this occasion, the phosphor-containing resin material 26b covers the first resin bodies 171, and enters the interstices between the adjacent first resin bodies 171 as well. Thus, the phosphor-containing resin material 26b is molded.
Thereafter, as shown in
Next, as shown in
According to this manufacturing method, the first resin bodies 171 and the second resin bodies 172 are accurately molded by using the molds 130, 140. Moreover, the thickness of the second resin bodies 172 is accurately set by using the molds 130, 140. Furthermore, the first resin bodies 171 and the second resin bodies 172 are formed without performing cutting by a blade.
As shown in
The unevenness 173 is provided by subjecting the top surface 171a and the side surfaces 171b of the first resin body 171 to satin processing, for example.
In the light emitting device 51, the provision of the unevenness 173 suppresses total reflection of light by the interface between the first resin body 171 and the second resin body 172, compared to a case where the interface is a flat surface. Moreover, the provision of the unevenness 173 increases the contact area between the first resin body 171 and the second resin body 172, and thus adhesion therebetween is improved.
Next, an example of a method of manufacturing the light emitting device 51 according to this embodiment will be described.
First of all, as shown in
Next, as shown in
Thereafter, heat treatment (mold curing) is performed while an upper surface of the lead frame 23 is pressed against the transparent resin 26a, and thus the transparent resin 26a is cured. Then, as shown in
Next, as shown in
Thereafter, the second resin bodies 172 are provided on the top surfaces and the side surfaces of the first resin bodies 171 as in the case of the method of manufacturing the light emitting device according to the first embodiment, which are shown in
Note that the method of manufacturing the light emitting device 51 described above is merely an example. For example, the first resin bodies 171 and the second resin bodies 172 may be formed using the molds illustrated in
Moreover, in the light emitting device 51, the first resin body 171 may include a diffusing agent, instead of the unevenness 173, or together with the unevenness 173. Silica is used, for example, as the diffusing agent, and diffuses light emitted from the light emitting element 14. Thus, total reflection by the interface between the first resin body 171 and the second resin body 172 is reduced.
As shown in
Such lens shape L is formed, for example, by using a manufacturing method using molds as illustrated in
Since the lens shape L is formed by use of the molds 101, 110, the lens shape L of each light emitting device 52 may be a shape other than the convex shape illustrated in
The modification is a modification of the lens shape L.
As shown in
The light emitting devices 52, 52a of the third embodiment make it possible to obtain optical characteristics of the lens shape L in addition to the operational effects of the light emitting device 1 of the first embodiment.
As shown in
In this respect, the third resin body 174 includes phosphor (not illustrated). The thickness of the third resin body 174 is uniform. Accordingly, the difference in the distance that light travels through the third resin body 174 becomes smaller among various angles at which the light is radially emitted from the light emitting device 14.
In the light emitting device 53, for example, red phosphor R is mixed into the third resin body 174, and green phosphor G is mixed into the second resin body 172. In addition, the light emitting element 14 emits blue light. Thus, blue light emitted from the light emitting element 14 and not absorbed by the red phosphor R or the green phosphor G, red light emitted from the red phosphor R, and green light emitted from the green phosphor G are emitted from the light emitting device 53 For this reason, the light emitted therefrom is white as a whole.
As shown in
As shown in
In this embodiment, electric potential is applied to the lead frame 31 and the second lead portion 12 from the outside, as well as thereby the lead frame 31 and the second lead portion 12 function as external electrodes. Meanwhile, there is no need to apply electric potential to the lead frame 32, and the lead frame 32 may be used as a lead frame dedicated to heat sinking. By this configuration, when multiple light emitting devices are mounted on a single module, the lead frames 32 may be connected to a common heat sink. Note that a ground potential may be applied to the lead frame 32, or the lead frame 32 may be in a floating state. Moreover, if solder balls are bonded to the lead frames 31, 32 and the second lead portion 12, what is termed as the Manhattan phenomenon can be inhibited when the light emitting device 60 is mounted on a motherboard. The Manhattan phenomenon is a phenomenon in which, when a device or the like is mounted on a substrate with multiple solder balls and the like interposed in between, the device stands up due to variation in timing at which the solder balls melt in a reflow furnace, and due to surface tension of the solder. This phenomenon causes mounting defects. In this embodiment, the layout of the lead frames is symmetrical with respect to the X direction, and the solder balls are arranged densely in the X direction. Thus, the Manhattan phenomenon is less likely to occur.
Moreover, in this embodiment, since the lead frame 31 is supported by the hanging pins 31b to 31e in three directions, the quality of bonding the wire 15 is excellent. Similarly, since the second lead portion 12 is supported by the hanging pins 12b to 12e in three directions, the quality of bonding the wire 16 is excellent.
The light emitting device 60 as described above can be manufactured in a method similar to that of the first embodiment described above by changing the basic pattern of each of the element regions P of the lead frame 23 in the step shown in
As shown in
Hence, the Zener diode chip 36 can be connected in parallel to the light emitting element 14 in this embodiment. As a result, resistance against electrostatic discharge (ESD) is improved. The configuration, manufacturing method, and operational effects of this embodiment other than those described above are the same as those of the first embodiment described above.
As shown in
As shown in
In this embodiment, the flip-type light emitting element 46 is used to eliminate a wire. This configuration improves the efficiency of outputting light upward, and enables the wire bonding step to be omitted. Moreover, breakage of a wire due to thermal stress of a first resin body 171 can be prevented. The configuration, manufacturing method, and operational effects of this embodiment other than those described above are the same as those of the first embodiment described above.
The embodiments and modifications thereof have been described above, but the present invention is not limited to these examples. For example, those skilled in the art may come up with a variation of any of the embodiments and modifications by adding or deleting the components or by changing the design of the components depending on the necessity, or may come up with a combination by combining the features of the embodiments depending on the necessity. Such variation and combination fall within the scope of the present invention as long as they include the gist of the present invention.
For example, in the embodiments and their modifications described above, given are examples in which: the light emitting element is an element which emits blue light; and the phosphor is a phosphor which absorbs blue light and emits yellow light, or phosphors which emit red light and green light. However, the present invention is not limited to this. The light emitting element may be an element which emits visible light other than the blue light, or may be an element which emits ultraviolet light or infrared light. Moreover, in the embodiments and their modifications described above, given are examples in which one or two resin bodies including phosphor are provided. However, three or more resin bodies including phosphor may be provided.
For example, a configuration may be adopted in which: the light emitting element is an element emitting ultraviolet light; and three second resin bodies respectively containing red phosphor, green phosphor, and blue phosphor is provided. Hence, all of the color components can be controlled by adjusting the types and the amounts of phosphors. Thus, latitude in color of the emitted light can be increased. In this case, a second resin body including a phosphor which emits light with shorter wavelength is disposed farther from the light emitting element. Alternatively, a second resin body including a phosphor with higher thermal dependency is disposed farther from the light emitting element. For example, the second resin body containing red phosphor, the second resin body containing green phosphor, and the second resin body containing blue phosphor are arranged in this order from the light emitting element.
As for the phosphor emitting blue light, the following substance may be given as an example:
(RE1-xSMx) 3 (AlyGa1-y) 5012:Ce
where 0≦x<1, 0≦y≦1, and RE is at least one selected from Y and Gd.
As for the phosphor emitting green light, the following substances may be given as an example in addition to the sialon-based green phosphor described above.
As for the phosphor emitting red light, the following substances may be given as an example in addition to the sialon-based red phosphor described above.
Note that as for the phosphor emitting yellow light, for example, the following phosphor may be used instead of the silicate-based phosphor described above. The phosphor is expressed with a general formula: MexSi12-(m+n)Al(m+n)OnN16-n:Re1yRe2z (where x, y, z, m, and n are coefficients). In this phosphor, part or all of the metal Me (one or two selected from a group consisting of Ca and Y) forming a solid solution with an alpha-sialon is substituted with a lanthanide metal Re1 (Re1 is one or more selected from a group consisting of Pr, Eu, Tb, Yb, and Er) which is the center of the light emission, or with two types of lanthanide metals Re1 and Re2 (Re2 is Dy), the lanthanide metal Re2 serving as a coactivator.
Moreover, the color of the light which the light emitting device as a whole emits is not limited to white. Any desired color tone may be achieved by adjusting the weight ratio R:G:B among the red phosphor, the green phosphor and the blue phosphor described above. For example, emission of white light ranging from incandescent-lamp-like white light to fluorescent-lamp-like white light can be achieved by setting the R:G:B weight ratio at any one of 1:1:1 to 7:1:1, 1:1:1 to 1:3:1, and 1:1:1 to 1:1:3.
In the first embodiment described above, an example is given in which the lead frame 23 is formed by wet etching. However, the present invention is not limited to this method, and the lead frame 23 may be formed by mechanical means such as a press.
In the first embodiment described above, an example is given in which the silver plating layers are formed on the upper and lower surfaces of the copper plate in the lead frame. However, the present invention is not limited to this. For example, the plating may be achieved by: forming the silver plating layers on the upper and lower surfaces of the copper plate; and forming a rhodium (Rh) plating layer on at least one of the silver plating layers. Alternatively, a copper (Cu) plating layer may be formed between the copper plate and each of the silver plating layers. Otherwise, the plating may be achieved by: forming nickel (Ni) plating layers on the upper and lower surfaces of the copper plate; and forming a plating layer of an alloy of gold and silver (Au—Ag alloy) or a palladium (Pd) plating layer on each of the nickel plating layers.
Moreover, a groove may be formed in a portion between a region where the die-mount material is to be applied on the upper surface of the lead frame and a region where the wire is to be bonded. Alternatively, a recess portion may be formed in the region where the die-mount material is to be applied on the upper surface of the lead frame. Accordingly, even when the amount of supplied die-amount material or the position into which to supply the die-mount material varies, the die-mount material is prevented from flowing out to the region where the wire is to be bonded, and it is thus possible to prevent the inhibition of the wire bonding.
In the embodiments and their modifications described above, examples are given in which one light emitting element is mounted on the light emitting device. However, multiple light emitting elements may be mounted on the light emitting device.
In the embodiments and their modifications described above, examples are given in which the lead made of the electrically conductive material is used as the base. However, the base is not limited to this configuration. For example, an electrically insulating substrate (such as a ceramic substrate) with a metal pattern formed thereon may be used. In a case of using the electrically insulating substrate, a single substrate with the metal pattern formed on a main surface thereof is used. For example, a first metal pattern on which to mount the light emitting element 14 and a second metal pattern to which to connect the wire 16 are provided spaced out on the main surface of the substrate. In this respect, the first metal pattern and the second metal pattern are used, respectively, as the first lead portion 11 and the second lead portion 12 in common with the above embodiments.
In the embodiments and their modifications described above, examples are given in which the recess portions DP provided on the side surfaces of the lead (base) are formed to extend from the first main surface s1 to the second main surface s2. However, the recess portions DP may be provided to extend from the first main surface s1 with a depth not reaching the second main surface s2. In other words, the recess portions DP may be shaped like a groove formed from the first main surface s1. In this case, the second resin body 172 is provided in a way that its coverage extends from the first main surface to at least a position of the lowermost end of the recess portions DP in the direction orthogonal to the first main surface s1 (a position farthest from the first main surface s1).
As described above, the light emitting devices of the embodiments brings about the following operational effects. The difference in the distance for the light travels through the second resin body 172 containing the phosphor 18 becomes smaller among angles at which the light is emitted radially from the light emitting element 14. Thus, variation in the wavelength conversion by the phosphor 18 can be suppressed among the angles at which the light is emitted radially. Accordingly, dependency of the chromaticity of the emitted light on its angle can be suppressed in the light emitting device 1.
Moreover, since the side surfaces 171b of the first resin body 171, the side surfaces 11s of the first lead portion 11, and the side surfaces 12s of the second lead portion 12 are covered with the second resin body 172, light leaking from the space between the first lead portion 11 and the second lead portion 12 also travels through the second resin body 172. Thus, the light leaking from the space between the first lead portion 11 and the second lead portion 12 are also subjected to the wavelength conversion by the phosphor 18.
Moreover, since the side surfaces 11s of the first lead portion 11 and the side surfaces 12s of the second lead portion 12, that is to say, the leading end surfaces of the hanging pins 11b to 11e, 12b to 12e are covered with the second resin body 172, corrosion of the first lead portion 11 and the second lead portion 12 is prevented from occurring from these surfaces.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modification as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-125746 | Jun 2010 | JP | national |
