SEMICONDUCTOR LIGHT-EMITTING DEVICE, METHOD FOR PRODUCING SAME, AND DISPLAY DEVICE

Abstract

A semiconductor light-emitting device (101) includes an LED chip (4), a lead (1) having a main surface (11) on which the LED chip (4) is mounted, and a resin package (5) covering the LED chip (4). The main surface (11) is roughened, and the main surface (11) is held in contact with the resin package (5). These configurations contribute to the downsizing of the semiconductor light-emitting device (101).

Claims

1-26. (canceled)

27. A LED package comprising: a first lead that includes a first portion and a second portion, the first portion having an obverse surface and a reverse surface, the second portion connected to the first portion, the second portion having an obverse surface and a reverse surface, the obverse surface of the second portion being flush with the obverse surface of the first portion, the second portion being smaller in size in a first direction perpendicular to the obverse surface of the first portion than the first portion; a LED chip electrically connected to the first lead and disposed on the obverse surface of the first lead; a second lead that is spaced from the first lead and includes a third portion and a fourth portion, the third portion having an obverse surface and a reverse surface, the fourth portion connected to the third portion, the fourth portion having an obverse surface and a reverse surface, the fourth portion being smaller in size in the first direction than the third portion; a die-bonding portion that covers a part of a first surface of the first lead; a wire that connects the LED chip and the second lead to each other; and a sealing resin that covers the obverse surface and reverse surface of the second portion, the obverse surface of the first portion, the obverse surface and reverse surface of the fourth portion, the obverse surface of the third portion, the LED chip and the wire, the sealing resin exposing the reverse surface of the first portion and the reverse surface of the third portion, wherein the second portion is greater in length in a second direction parallel to the obverse surface of the first portion than each of the fourth portion and the LED chip, and the first lead and the second lead respectively have a first buried surface and a second buried surface in the sealing resin.

28. The LED package according to claim 27, wherein the sealing resin has a center in the second direction and a third direction that is perpendicular to both the second direction and the first direction, and the second portion overlaps with the center of the sealing resin as viewed in the first direction.

29. The LED package according to claim 27, wherein the first lead has a curved surface that connects the reverse surface of the second portion and the first portion to each other.

30. The LED package according to claim 27, wherein the reverse surface of the first portion and the reverse surface of the third portion are both spaced apart from a perimeter edge of the sealing resin as viewed in the first direction.

31. The LED package according to claim 27, wherein the first portion includes a side surface that is opposite to the second portion and exposed from the sealing resin.

32. The LED package according to claim 27, wherein the sealing resin has an obverse surface and a reverse surface that are spaced apart from each other in the first direction, and a distance between the obverse surface of the sealing resin and the obverse surface of the second portion in the first direction is greater than a distance between the reverse surface of the sealing resin and the reverse surface of the second portion in the first direction.

33. The LED package according to claim 28, wherein at least a part of the second portion is greater in size measured in the third direction than the LED chip.

34. The LED package according to claim 31, wherein the exposed side surface of the first portion is spaced apart from a perimeter edge of the sealing resin as viewed in the second direction.

35. The LED package according to claim 31, wherein the sealing resin has an obverse surface and a reverse surface that are spaced apart from each other in the first direction, and the exposed side surface of the first portion is closer to the reverse surface of the sealing resin than to the obverse surface of the sealing resin.

36. The LED package according to claim 27, wherein at least a part of the wire extends along the first direction.

37. The LED package according to claim 27, wherein the reverse surface of the first portion and the reverse surface of the third portion are same in size measured in a third direction perpendicular to both the second direction and the first direction.

38. The LED package according to claim 27, wherein at least a part of the wire overlaps with the fourth portion as viewed in the first direction.

39. The LED package according to claim 27, wherein the sealing resin comprises a first resin portion allowing passage of light from the LED chip, and the first resin portion covers at least the obverse surface of the second portion, the obverse surface of the fourth portion, the LED chip and the wire.

40. The LED package according to claim 39, wherein the sealing resin comprises a second resin portion that is opaque and held in contact with the first resin portion, and the second resin portion covers at least the reverse surface of the second portion and the reverse surface of the fourth portion.

41. The LED package according to claim 40, wherein the second resin portion is white.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0038] FIG. 1 is a perspective view showing an example of a semiconductor light-emitting device according to the present invention.

[0039] FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1.

[0040] FIG. 3 is a bottom view of the semiconductor light-emitting device shown in FIG. 1.

[0041] FIG. 4 is a fragmentary plan view of a lead frame employed in an example of a manufacturing process of the semiconductor light-emitting device shown in FIG. 1.

[0042] FIG. 5 is a fragmentary plan view of the lead frame subjected to etching in an example of a manufacturing process of the semiconductor light-emitting device shown in FIG. 1.

[0043] FIG. 6 is a fragmentary cross-sectional view taken along a line VI-VI in FIG. 5.

[0044] FIG. 7 is a fragmentary plan view of the lead frame with LED chips mounted thereon, in an example of a manufacturing process of the semiconductor light-emitting device shown in FIG. 1.

[0045] FIG. 8 is a fragmentary plan view of the lead frame encapsulated in a resin package, in an example of a manufacturing process of the semiconductor light-emitting device shown in FIG. 1.

[0046] FIG. 9 is a perspective view showing another example of a semiconductor light-emitting device according to the present invention.

[0047] FIG. 10 is a cross-sectional view taken along a line X-X in FIG. 9.

[0048] FIG. 11 is a fragmentary cross-sectional view showing an opaque portion formed in an example of a manufacturing process of the semiconductor light-emitting device shown in FIG. 9.

[0049] FIG. 12 is a perspective view showing an example of a display device including the semiconductor light-emitting device according to the present invention.

[0050] FIG. 13 is a plan view showing the display device shown in FIG. 12.

[0051] FIG. 14 is a cross-sectional view taken along a line XIV-XIV in FIG. 13.

[0052] FIG. 15 is a fragmentary plan view of another example of a display device including the semiconductor light-emitting device according to the present invention.

[0053] FIG. 16 is a fragmentary cross-sectional view taken along a line XVI-XVI in FIG. 15.

[0054] FIG. 17 is a plan view showing an example of a conventional semiconductor light-emitting device.

[0055] FIG. 18 is a cross-sectional view showing an example of a conventional display device.

DESCRIPTION OF EMBODIMENTS

[0056] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0057] FIGS. 1 to 3 depict an example of a semiconductor light-emitting device according to an embodiment of the present invention. The semiconductor light-emitting device 101 according to this embodiment includes a pair of leads 1, 2, a metal joint layer 3, an LED chip 4, and a resin package 5. In FIG. 1, the metal joint layer 3 is not shown for the sake of convenience. The semiconductor light-emitting device 101 is configured as a small and thin device, having dimensions of approximately 0.6 mm in length, 0.3 mm in width, and 0.2 mm in thickness.

[0058] The pair of leads 1, 2 serve to support the LED chip 4 and supply power thereto. The leads 1, 2 are formed of Cu or an alloy thereof, in a thickness of slightly less than 0.1 mm. The lead 1 includes a main surface 11, four side faces 13, two buried surfaces 14, three drawn-out portions 15, and a mounting terminal 16. The lead 2 includes a main surface 21, four side faces 23, two buried surfaces 24, three drawn-out portions 25, and a mounting terminal 26.

[0059] The main surface 11 is a portion on which the LED chip 4 is to be die-bonded, and has dimensions of approximately 0.27 mm0.24 mm. The main surface 21 is a portion on which a wire 6 is to be bonded, and has dimensions of approximately 0.19 mm0.24 mm. The main surface 11 and the main surface 21 are both covered with the resin package 5.

[0060] As shown in FIG. 2, the main surface 11 is plated with silver, and an Ag-plated layer 12 is formed thereon. The surface of the Ag-plated layer 12 is roughened and has higher surface roughness than the remaining portions of the lead 1. The main surface 21 is also plated with silver, and an Ag-plated layer 22 is formed thereon. The surface of the Ag-plated layer 22 is roughened and has higher surface roughness than the remaining portions of the lead 2. Since the Ag-plated layers 12, 22 have a rough surface, the respective portions of the main surfaces 11, 21 covered with the Ag-plated layers 12, 22 present a rough surface. Examples of methods to roughen the surface of the Ag-plated layers 12, 22 include selecting a plating process that provides a rough surface, and performing shot-blasting after the plating. The surface roughness of the Ag-plated layers 12, 22 may be approximately 1 m. For example, the surfaces may have an arithmetic surface roughness Ra of 0.08 to 0.20. The Ag-plated layer 12 has dimensions of approximately 0.25 mm0.21 mm, and the Ag-plated layer 22 has dimensions of approximately 0.13 mm0.2 mm.

[0061] The mounting terminals 16, 26 are to be used for surface-mounting the semiconductor light-emitting device 101 and, as shown in FIG. 2, formed of the respective portions of the leads 1, 2 extending in a direction opposite to the LED chip 4 and exposed from the resin package 5. In this embodiment, the mounting terminals 16, 26 have dimensions of approximately 0.19 mm0.27 mm.

[0062] The side faces 13, 23 are faces extending in a direction in which the main surfaces 11, 21 and the mounting terminals 16, 26 are separated from each other, respectively. In this embodiment, nearly the entirety of the side faces 13, 23 is covered with the resin package 5.

[0063] The drawn-out portions 15, 25 extend from the side faces 13, 23 and each have an end face exposed from the resin package 5. The drawn-out portions 15, 25 are formed, for example, by cutting a portion connecting between the pair of leads 1, 2 and a frame portion of a lead frame.

[0064] The buried surfaces 14, 24 correspond to the surfaces of partially scraped portions of the leads 1, 2, and oriented opposite to the main surface 11, 21. In this embodiment, the leads 1, 2 each include two buried surfaces 14, 24. The base portion of each of the buried surfaces 14, 24 is formed in a curved shape.

[0065] The metal joint layer 3 serves to couple the LED chip 4 and the Ag-plated layer 12, and is composed of an alloy of Au and one of Sn, Si, and Ge. The metal joint layer 3 has a thickness of, for example, 1 pm or less.

[0066] The LED chip 4 is the light source of the semiconductor light-emitting device 101, and has a layered structure including, for example, an n-type semiconductor layer and a p-type semiconductor layer, and an active layer interleaved therebetween. The LED chip 4 is, for example, capable of emitting blue light in the case of being constituted of an InGaN-based semiconductor, and has a size of approximately 0.1 mm square and a thickness of approximately 50 m. The upper face of the LED chip 4 is connected to the main surface 21 through the wire 6. Here, the LED chip 4 may be constituted of an AlGaNInP-based semiconductor, for example.

[0067] The resin package 5 serves to protect the LED chip 4 and the wire 6. The resin package 5 is formed of a resin that transmits the light from the LED chip 4, for example an epoxy resin. In the case where a fluorescent material that emits yellow light upon being excited by blue light is mixed in the resin package 5, the semiconductor light-emitting device 101 becomes capable of emitting white light. In this embodiment, the resin package 5 has dimensions of approximately 0.6 mm0.3 mm in a plan view, and a thickness of slightly less than 0.2 mm.

[0068] Referring now to FIGS. 4 to 8, an example of the manufacturing method of the semiconductor light-emitting device 101 will be described hereunder.

[0069] First, a lead frame 10 as shown in FIG. 4 is prepared. The lead frame 10 includes a plurality of leads 1, 2 and frame portions 18 connecting between the leads 1, 2. The lead frame is formed of, for example, Cu or an alloy thereof in thickness of slightly less than 0.1 mm. The lead frame 10 may be formed by punching a metal plate of, for example, Cu or an alloy thereof.

[0070] Then an etching process is applied to the lead frame 10. The etching is applied to a region of the lead frame 10 opposite to the main surface 11, 21. The etching reduces the thickness of a part of the lead frame 10, as shown in FIGS. 5 and 6, so that a plurality of the mounting terminals 16, 26 and a plurality of the buried surfaces 14, 24 are formed. Here, hatched portions in FIG. 5 correspond to the mounting terminals 16, 26 in a plan view.

[0071] Proceeding to FIG. 7, the lead frame 10 is plated. As a result, the Ag-plated layers 12, 22 are formed on the lead frame 10. For this plating process, it is preferable to select a method that is more likely to form a relative rough surface on the Ag-plated layers 12, 22, so that the Ag-plated layers 12, 22 obtain a surface roughness of approximately 1 m. Alternatively, a shot-blasting process may be applied to the Ag-plated layers 12, 22, to thereby roughen the surfaces of the Ag-plated layers 12, 22.

[0072] Then the LED chip 4 is mounted on the main surface 11. To mount the LED chip 4, the metal joint layer 3 is employed. To couple the LED chip 4 to the main surface 11 with the metal joint layer 3, for example the LED chip 4 is pressed against the Ag-plated layer 12 with the metal joint layer 3 therebetween and the atmospheric temperature is raised to 200 to 350 C., and then the LED chip 4 is ultrasonically caused to vibrate. Through such a process, the metal joint layer 3 forms a eutectic with both of the Ag-plated layer 12 and the LED chip 4. Therefore, the LED chip 4 is firmly fixed to the main surface 11. Then the LED chip 4 is connected to the lead 2 with the wire 6.

[0073] Then as shown in FIG. 8, the resin package 50 is formed. To form the resin package 50, a die molding process is employed using, for example, a transparent epoxy resin material, or a mixture of the transparent epoxy resin material and a fluorescent material. The resin package 50 covers nearly the entirety of the lead frame 10, all of the LED chips 4 and wires 6. Thereafter, the lead frame 10 is cut along cutting lines 55. Through the process described thus far, the semiconductor light-emitting device 101 shown in FIGS. 1 to 3 can be obtained.

[0074] The semiconductor light-emitting device 101 provides the following advantageous effects.

[0075] According to this embodiment, the resin package 5 is in contact with the main surfaces 11, 21, which are rough surfaces. Such a configuration increases the adhesion strength between the resin package 5 and the leads 1, 2. Therefore, the leads 1, 2 can be prevented from separating from the resin package 5, which allows the semiconductor light-emitting device 101 to be manufactured in a smaller size.

[0076] The resin package 5 covers the side faces 13, 23 of the leads 1, 2. Accordingly, the resin package 5 and the leads 1, 2 are coupled with each other via a larger joint area. In addition, the leads 1, 2 are held by the resin package 5 via the side faces 13, 23. Such a configuration further assures the prevention of the separation of the leads 1, 2 from the resin package 5.

[0077] Further, the resin package 5 also holds the leads 1, 2 in the thickness direction, via the portions of the resin package 5 in contact with the buried surfaces 14, 24 and the main surfaces 11, 21. Such a configuration is quite effective to prevent the leads 1, 2 from separating from the resin package 5. In addition, the drawn-out portions 15, 25 extending so as to expose the leading end face from the resin package 5 even further assures the prevention of the separation of the leads 1, 2.

[0078] The semiconductor light-emitting device 101 according to this embodiment is free from orifices about which some measures have to be taken to prevent leakage of the resin material in the forming process of the resin package 5. Therefore, the resin package 5 can be formed in substantially the same size as the overall semiconductor light-emitting device 101. In other words, the semiconductor light-emitting device 101 can be manufactured in a size substantially equal to the resin package 5 having the minimum necessary size to properly protect the LED chip 4 and the wire 6. Consequently, the reduction in size of the semiconductor light-emitting device 101 can be achieved.

[0079] The resin package 5 surrounding the mounting terminals 16, 26 is formed of a material that has very low wettability with respect to solder. Accordingly, in the case of mounting the semiconductor light-emitting device 101 on a printed circuit board 7 having an interconnect pattern 71 formed thereon as shown in FIG. 2, solder 74 is blocked by the resin package 5 and can barely protrude from the mounting terminals 16, 26. Therefore, when a plurality of the semiconductor light-emitting devices 101 are mounted on the same printed circuit board 7, the solder 74 of adjacent devices is kept from interfering with each other. Consequently, the semiconductor light-emitting devices 101 can be mounted in higher density.

[0080] The Ag-plated layers 12, 22 each constitute a reflecting surface having a high reflectance. Accordingly, the light emitted from the LED chip 4 toward the main surfaces 11, 21 is reflected, being barely absorbed. Such a configuration contributes to increasing the luminance of the semiconductor light-emitting device 101. In the case where the LED chip 4 emits blue light in particular, the Ag-plated layers 12, 22 are suitable for reflecting the blue light. In addition, heat generated when the LED chip 4 emits the light can be efficiently released from the main surface 11 toward the printed circuit board 7, through the mounting terminal 16. This is advantageous for increasing the luminance of the semiconductor light-emitting device 101 by supplying higher power.

[0081] The metal joint layer 3 enables the LED chip 4 and the Ag-plated layer 12 to be coupled with each other in a eutectic state. As a result, the LED chip 4 can be firmly fixed to the main surface 11. Therefore, the LED chip 4 formed in a significantly small size can be properly fixed. Further, since the LED chip 4 can be bonded with a sufficient adhesion strength, it is not necessary to apply a large amount of the metal joint layer 3 that protrudes from the around the LED chip 4. Therefore, the light from the LED chip 4 can be prevented from being absorbed by the metal joint layer 3. Such a configuration allows, therefore, the luminance of the semiconductor light-emitting device 101 to be further upgraded.

[0082] FIGS. 9 to 11 depict another embodiment of the present invention. In these drawings, the constituents same as or similar to those of the foregoing embodiment are given the same numeral.

[0083] FIGS. 9 and 10 depict another example of the semiconductor light-emitting device according to the present invention. The semiconductor light-emitting device 102 according to this embodiment is different from the semiconductor light-emitting device 101 in the configuration of the resin package 5.

[0084] In this embodiment, the resin package 5 includes a transparent portion 51 and an opaque portion 52. The transparent portion 51 is formed of a material that transmits the light from the LED chip 4, for example a transparent epoxy resin, or a mixture of the transparent epoxy resin and a fluorescent material. The transparent portion 51 covers the LED chip 4, and is in contact with the main surfaces 11, 21. The opaque portion 52 is formed of a material that does not transmit the light from the LED chip 4, such as a white resin. The opaque portion 52 is located lower than the main surfaces 11, 21, and covers the side faces 13, 23 and the buried surfaces 14, 24 of the leads 1, 2.

[0085] In the manufacturing method of the semiconductor light-emitting device 102, the opaque portion 52 is formed on the lead frame 10 as shown in FIG. 11, for example with a white resin, after the lead frame 10 is prepared as shown in FIG. 4. The opaque portion 52 may be formed after the Ag-plated layers 12, 22 are formed. The above is followed by the mounting of the LED chip 4, the bonding of the wire 6, and the forming of the transparent portion similar to the resin package 50 shown in FIG. 8, and then the lead frame 10 is cut. The semiconductor light-emitting device 102 can thus be obtained.

[0086] In the semiconductor light-emitting device 102 thus configured, the portion between the leads 1, 2 and the periphery thereof are filled with the opaque portion 52. Accordingly, the light from the LED chip 4 can be prevented from unduly leaking to the side of the mounting terminals 16, 26. In addition, the opaque portion 52 formed of a white resin has a relatively high reflectance. Therefore, the luminance of the semiconductor light-emitting device 102 can be increased.

[0087] The semiconductor light-emitting device according to the present invention is not limited to the foregoing embodiments. Specific configurations of the constituents of the semiconductor light-emitting device according to the present invention may be modified in various manners.

[0088] FIGS. 12 to 14 depict an example of a display device according to the present invention. The display device 201 according to this embodiment includes the printed circuit board 7, seven semiconductor light-emitting devices 101, and a reflector 8. The display device 201 is constituted as what is known as a 7-segment type display device capable of displaying numerals and alphabets.

[0089] The printed circuit board 7 includes, for example, a resin layer and a patterned metal layer stacked thereon, and serves as the base of the display device 201. In this embodiment, the printed circuit board 7 is formed in a slender rectangular shape. The interconnect pattern 71 and a plurality of terminals 72 are provided on the printed circuit board 7. The terminals 72 are used for incorporating the display device 201 in an electronic apparatus and the like. The interconnect pattern 71 serves for electrical connection between the terminals 72 and the semiconductor light-emitting devices 101.

[0090] The semiconductor light-emitting device 101 is the light source of the display device 201. In this embodiment, seven pieces of the semiconductor light-emitting device 101 are employed, and mounted on the printed circuit board 7.

[0091] The reflector 8 has a slender rectangular plate shape and is formed of, for example, a white resin in this embodiment. The reflector 8 includes seven openings 81. The openings 81 each have a slender hexagonal shape in a plan view. As shown in FIG. 13, the seven openings 81 are arranged so as to form a numeral of 8 as a whole.

[0092] The openings 81 accommodate one each of the semiconductor light-emitting device 101. The inner wall of each opening 81 serves as a reflecting surface 82. In this embodiment, each of the openings 81 includes six reflecting surfaces 82. These reflecting surfaces 82 constitute three pairs of reflecting surfaces 82, each pair opposing each other across the semiconductor light-emitting device 101. As shown in FIG. 14, each pair of the reflecting surfaces 82 are inclined so as to increase the distance therebetween toward a position more distant from the mounting face in a direction of the normal of the mounting face, on which the semiconductor light-emitting device 101 is mounted.

[0093] The display device 201 provides the following advantageous effects.

[0094] The configuration of the display device 201 eliminates the need to fill the openings 81 with a light-transmissive resin, after the semiconductor light-emitting device is mounted. Accordingly, the manufacturing process of the display device 201 can be simplified and the manufacturing cost thereof can also be reduced.

[0095] Further, it is not necessary to connect a wire to the semiconductor light-emitting device 101. Therefore, there is no need to insert a capillary for bonding a wire in the opening 81. In addition, it is not necessary to insert a device, such as a nozzle, for filling the opening 81 with a light-transmissive resin. Thus, the opening 81 can be small as long as it accommodates the semiconductor light-emitting device 101 therein. In addition to the above, the semiconductor light-emitting device 101 is formed in a relatively small size as already described, and hence the footprint can be reduced when mounted on another device. Consequently, the display device 201 can be manufactured in a smaller size.

[0096] FIGS. 15 and 16 depict another example of the display device according to the present invention. The display device 202 according to this embodiment is different from the foregoing embodiment in that the dot matrix type display is adopted.

[0097] In the display device 202, the reflector 8 includes a multitude of openings 81. These openings 81 are arranged in a matrix pattern in a plan view. Each of the openings 81 may have, for example, a square shape in a plan view. Each of the openings 81 includes the semiconductor light-emitting device 101. In other words, the display device 202 includes a multitude of semiconductor light-emitting devices 101 mounted on the printed circuit board 7 in a matrix pattern.

[0098] The display device 202 can also be manufactured in a smaller size and the manufacturing cost thereof can be reduced. In particular, since the openings 81 can be formed in a smaller size, the multitude of openings 81 can be arranged in a high density. Therefore, the display device 202 can provide a higher-definition display.

[0099] The display device including the semiconductor light-emitting device according to the present invention is not limited to the foregoing embodiments. Specific configurations of the constituents of the display device including the semiconductor light-emitting device according to the present invention may be modified in various manners.

[0100] In place of the semiconductor light-emitting device 101, the semiconductor light-emitting device 102 may be employed as the light source of the display devices 201, 202.