This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2011-200544, filed on Sep. 14, 2011; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a semiconductor light emitting device and a method for manufacturing the same.
Semiconductor light emitting devices have low power consumption and long lives and are beginning to be used in various applications such as display devices, illumination appliances, and the like. For example, a semiconductor light emitting device in which a light emitting diode (LED) is mounted can be small and can be driven by a low voltage; and the control of the light emission also is easy. Therefore, there is a wide range of applications for such a semiconductor light emitting device.
On the other hand, technology is necessary to reduce the power consumption by efficiently utilizing the light emitted from semiconductor light emitting devices. For example, in the package of a semiconductor light emitting device in which an LED is mounted, an enclosure is provided to control the light distribution by reflecting the light emission of the LED. However, there are cases where the enclosure which is made of a resin undergoes thermal denaturation when mounting the light emitting element and the other components in the interior of the package; and the light emission intensity may decrease. It is also problematic that the formation of the enclosure itself increases the manufacturing cost. Therefore, a semiconductor light emitting device and a method for manufacturing the semiconductor light emitting device are necessary to avoid the thermal denaturation of the resin package and realize inexpensive manufacturing.
In general, according to one embodiment, a method for manufacturing a semiconductor light emitting device, includes: preparing a metal plate including a plurality of first frames and a plurality of second frames, the first frames being disposed alternately with the second frames to be apart from the second frames, a light emitting element being affixed to each of the first frames and connected via a metal wire to an adjacent second frame; forming a first resin on a first major surface of the metal plate to cover the first frames, the second frames, and the light emitting elements; making a trench from a second major surface side opposite to the first major surface to delineate resin packages by dividing the metal plate and the first resin; filling a second resin into an interior of the trench from the first major surface side; and forming the resin packages by dividing the second resin along the trench, an outer edge of the first resin being covered with the second resin.
In general, according to another embodiment, a semiconductor light emitting device, includes: a first frame; a light emitting element affixed to the first frame; a second frame disposed apart from the first frame, the second frame being electrically connected to an electrode of the light emitting element via a metal wire; and a resin package including a first resin and a second resin, the first resin being configured to cover the light emitting element, the first frame, and the second frame, the second resin being configured to cover an outer edge of the first resin and reflect light emitted by the light emitting element, a cross-sectional area of the first resin in a cross-section parallel to a front surface of the first frame being configured to enlarge from the front surface of the first frame toward a front surface of the first resin opposite to the first frame, a back surface of the first frame and a back surface of the second frame being exposed at one surface of the resin package, the back surface of the first frame being on a side opposite to the front surface of the first frame having the affixed light emitting element, the back surface of the second frame being on a side opposite to the front surface of the second frame having the connected metal wire, the first frame and the second frame being positioned on an inner side of an outer edge of the resin package when viewed in plan by projection onto a plane parallel to the one surface.
Embodiments of the invention will now be described with reference to the drawings. Similar portions in the drawings are marked with like numerals; a detailed description thereof is omitted as appropriate; and portions that are different are described. For convenience in the specification, there are cases where the configuration of the semiconductor light emitting device is described based on an XYZ orthogonal coordinate system illustrated in the drawings.
In the specification, the concept of covering includes both the case of the covering component being in contact with the covered component and the case of not being in contact. For example, another material may be interposed between a first resin 19a and the LED 14, the ZD 16, and the leadframes 11 and 12 that are covered with the first resin 19a.
As illustrated in
The leadframes 11 and 12 are, for example, flat plates arranged in the same plane and are made of the same conductive material. For example, the leadframes 11 and 12 are copper plates with silver plating performed on the front surfaces and the back surfaces of the leadframes 11 and 12. Thereby, light radiated by the LED 14 is reflected.
The resin package 18 includes the first resin 19a and a second resin 19b, where the first resin 19a covers the LED 14, the ZD 16, the leadframe 11, and the leadframe 12 and the second resin 19b covers the outer edge of the first resin 19a. The first resin 19a transmits the light radiated by the LED 14. On the other hand, the second resin 19b provided around the outer edge of the first resin 19a includes a reflective material configured to reflect the light of the LED 14 and reflects the light of the LED 14 that is radiated in the X direction and the Y direction.
Thus, the LED 14 is disposed in a state of the leadframes 11 and 12, which are configured to reflect the light radiated by the LED 14, and the second resin 19b, which functions as an enclosure, being provided around the LED 14. Thereby, the light of the LED 14 is radiated in the Z direction; and the directivity and the light output of the semiconductor light emitting device 100 are improved. For example, it is possible to control the directivity by changing the reflectance by controlling the amount of the reflective material included in the second resin. Also, the directivity may be controlled by changing the thickness of the second resin 19b in the X direction and the Y direction.
The material of the LED 14 used in this embodiment is, for example, a semiconductor layer including gallium nitride (GaN) and the like stacked on a sapphire substrate. The chip has, for example, a rectangular parallelepiped configuration; and the p-electrode 14a and the n-electrode 14b are provided on the upper surface of the chip. For example, the LED 14 radiates blue light when a drive current is caused to flow between the p-electrode 14a and the n-electrode 14b.
The LED 14 is affixed via a die mount material 13 that is bonded to the front surface of the leadframe 11 to cover the front surface of the leadframe 11. In the LED 14 according to this embodiment, the active region (the light emitting portion) is electrically isolated from the back surface of the LED chip by an insulative substrate (the sapphire substrate). Accordingly, the die mount material 13 may be conductive or insulative. The die mount material 13 may include, for example, a bonding agent made of a silver paste or a transparent resin paste.
On the other hand, the affixation of the ZD 16 includes, for example, a eutectic mount which is bonded by forming a silicide between the frame front surface and the silicon surface of the chip back surface. Therefore, the temperature of the die bonding is a high temperature; and in the case where, for example, the enclosure is formed beforehand on the frame that is used, there are cases where the reflectance is reduced by denaturation of the resin included in the enclosure and the light output decreases.
Conversely, in this embodiment, the enclosure is formed after affixing the LED 14 and the ZD 16 to the leadframes 11 and 12. Thereby, the ZD 16 can be affixed to the leadframe 12 at a high temperature. Instead of a silver paste or a bonding agent, the light emitting element 14 also can be affixed using solder or eutectic solder. The bonding is possible at a high temperature even in the case where another peripheral component is used instead of the ZD 16. In other words, it is possible to use a component that is affixed to at least one selected from the leadframe 11 and the leadframe 12 at a higher temperature than the affixing of the LED 14.
A method for manufacturing the semiconductor light emitting device 100 will now be described with reference to
First, as illustrated in
The leadframes 11 and 12 are formed in a metal plate 23 made of, for example, copper. As illustrated in
As illustrated in
Each of the frame pairs P includes the mutually-separated leadframes 11 and 12. The multiple leadframes 11 and the multiple leadframes 12 are disposed alternately in the X direction. In the dicing region D, mutually-adjacent frame pairs P are connected by linking portions (suspension pins) 23a to 23e.
For example, focusing now on one frame pair P positioned in the center of
The linking portions 23a to 23e are formed to be thinner than the leadframes 11 and 12 by performing half-etching from a back surface 23B (a second major surface) side of the metal plate 23. For example, patterning is performed to half of the thickness of the leadframes 11 and 12.
Then, as illustrated in
A lower die 101 that corresponds to the upper die 102 has a recess 101a in the engagement surface (the upper surface) of the lower die 101. Then, a resin material 26 used to form the first resin 19a is filled into the recess 101a. The first resin 19a may include, for example, a resin having a main component of silicone.
A prescribed fluorescer may be dispersed in the resin material 26. For example, a liquid or semi-liquid resin material 26 including a fluorescer is prepared by mixing the fluorescer into a transparent silicone resin and by stirring. In the case where the fluorescer is mixed into a transparent silicone resin, the dispersion can be uniform by using a thixotropic agent. Then, the resin material 26 into which the fluorescer is dispersed is filled into the recess 101a using a dispenser.
Then, as illustrated in
As described above, the linking portions 23a to 23e that link the mutually-adjacent leadframes 11 and leadframes 12 are patterned to be half of the thickness of the leadframes 11 and 12 at the back surface 23B on the side opposite to the front surface 23A which is the side from which the first resin 19a is filled. Therefore, the first resin 19a is formed to extend around to the back surface side of the linking portions 23a to 23e; and the bonding strength between the first resin 19a and the leadframes 11 and 12 is increased.
Then, after curing the resin material 26 by increasing the temperature of the die, the first resin 19a is released from the recess 101a by opening the upper die 102 and the lower die 101 as illustrated in
Continuing, a dicing sheet 34 is adhered to the front surface of the first resin 19a; and the reinforcing sheet 24 is peeled from the back surface 23B (the second major surface) of the metal plate 23. Continuing as illustrated in
Then, as illustrated in
Continuing as illustrated in
The second resin 19b may include, for example, a white resin including titanium oxide as a reflective material. Further, it is favorable for the first resin 19a and the second resin 19b to include the same material to increase the adhesion between the first resin 19a and the second resin 19b.
The second resin 19b may include, for example, the same silicone resin as the first resin 19a. For example, a fine powder of titanium oxide is dispersed as the reflective material.
Then, as illustrated in
Continuing as illustrated in
In the process recited above, the second resin 19b may be filled after increasing the width of the trench 25 by expanding the dicing sheet 35. Thereby, the width of the second resin 19b can be wider.
As illustrated in
The multiple linking portions 23a to 23e extend between the leadframes 11 and 12 and the second resin 19b; and the first resin 19a is filled between the multiple linking portions 23a to 23e. As illustrated in
As illustrated in
In this embodiment, the end surfaces of the linking portions (the suspension pins) 23a to 23e are not exposed at the side surface of the resin package 18. Accordingly, the semiconductor light emitting device 100 is mounted to the circuit substrate in a state in which the entire package is covered with an insulative resin. Therefore, short failures can be suppressed; and high-density mounting of the semiconductor light emitting device 100 and the circuit components is possible.
In this embodiment, it is possible to easily manufacture the resin package 18 including the enclosure by, for example, performing vacuum forming twice. Thereby, the manufacturing cost can be reduced. The high-temperature mounting of the light emitting elements and the peripheral components is possible because the resin package 18 is formed after mounting the light emitting elements and the peripheral components of the light emitting elements. Thereby, it is possible to increase the adhesion strength of the light emitting elements and the peripheral components to the leadframes as well as reduce the contact resistance. Thereby, the reliability of the semiconductor light emitting device 100 can be increased.
As described above, the fluorescer may be dispersed in the first resin 19a; and the wavelength of the light radiated from the LED 14 may be converted. For example, by dispersing a silicate-based fluorescer in the first resin 19a, a portion of the blue light radiated from the LED 14 is absorbed and yellow fluorescence is radiated. Thereby, the semiconductor light emitting device 100 emits white light by the mixing of the blue light radiated by the LED 14 and the yellow light radiated from the fluorescer.
Other than using a silicate-based fluorescer to emit a yellow fluorescence, for example, a silicate-based fluorescer, a YAG-based fluorescer, a sialon-based red fluorescer, a green fluorescer, and the like may be used to emit yellowish green, yellow, or orange light.
In the semiconductor light emitting device 200, the cross-sectional area of the first resin 19a of a resin package 28 in a cross-section parallel to the front surface of the leadframe 11 enlarges from the front surface of the leadframe 11 toward the front surface of the first resin 19a opposite to the leadframe 11.
In other words, as illustrated in
As illustrated in
Manufacturing processes of the semiconductor light emitting device 200 will now be described with reference to
In this embodiment as illustrated in
Then, as illustrated in
Continuing as illustrated in
Then, as illustrated in
Continuing as illustrated in
In this embodiment as well, the second resin 19b may be filled after increasing the width of the trench 45 by expanding the dicing sheet 35. Thereby, the width of the second resin 19b can be wider.
Although the semiconductor light emitting device and the method for manufacturing semiconductor light emitting device according to the first and second embodiments are described above, the embodiments are not limited to the examples recited above. It is also possible to use other methods. For example, it is possible to use screen printing, a dispenser, and the like when filling the second resin into the trench provided at the outer circumferences of the resin packages.
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 modifications as would fall within the scope and spirit of the invention.
Number | Date | Country | Kind |
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2011-200544 | Sep 2011 | JP | national |