LIGHT EMITTING DEVICE AND METHOD FOR MANUFACTURING SAME

• US 20140042481A1
• Filed: 10/17/2013
• Published: 02/13/2014
• Est. Priority Date: 04/20/2011
• Status: Abandoned Application

• Current Assignee: ELM Incorporated
• Original Assignee: ELM Incorporated
• Inventors: INOUE, Tomio, MIYAHARA, Takakazu
• Application Number:
  US14/056,303
• Publication Number:
  US 20140042481A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: H01L 33/486 adapted for surface mounting
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

A light emitting device which is inexpensive and has excellent characteristics and a method for manufacturing the same are provided. In the present invention, a chip-size package including a reflection wall is formed by forming a double structure in which a fluorescent material-containing film piece 2 is bonded on a light extraction surface of a semiconductor light emitting element 6 having bumps 4 and 5 on an electrode-formed surface, and covering an exposed surface of the double structure other than a bump mounting surface 7 and a light exit surface 8 with the reflection wall 3, whereby it is possible to provide a light emitting device which does not need a package substrate, is inexpensive, and has excellent brightness characteristics and heat radiation characteristics, and a manufacturing method having excellent chromaticity yield.

Claims

1. A light emitting device wherein

on a semiconductor light emitting element which emits blue light, purple light, or ultraviolet light, has two opposed principal surfaces one of which is a light extraction surface and another of which is an electrode-formed surface, and has a bump on the electrode-formed surface, a fluorescent material-containing film piece which has two opposed principal surfaces each of which is the same in size as or larger in size than the light extraction surface, one of which is a light entrance surface, and another of which is a light exit surface is overlaid such that the light extraction surface is opposed to the light entrance surface, and

an exposed surface other than the electrode-formed surface of the semiconductor light emitting element (including a surface of the bump) and the light exit surface of the fluorescent material-containing film piece or an exposed surface other than the light exit surface of the fluorescent material-containing film piece and a bump mounting surface of the bump at which the semiconductor light emitting element is mounted on an external substrate is covered with a reflection wall, and the bump mounting surface or an electrode on the electrode-formed surface protrudes from a lowest bottom surface of the reflection wall.

2. The light emitting device according to claim 1, wherein the semiconductor light emitting element and the fluorescent material-containing film piece are bonded to each other by a silicon resin or a silicon resin which contains a fluorescent material or a pigment for correcting chromaticity or color temperature.

3. The light emitting device according to claim 1, wherein a material of the fluorescent material-containing film piece is a material obtained by dispersing powder of several types of fluorescent materials in a silicon resin, and a material of the reflection wall is a material obtained by dispersing titanium oxide fine powder in a silicon resin.

4. A method for manufacturing the light emitting device according to claim 1, the method comprising:

an A1 step of attaching a fluorescent material-containing film to a dicing sheet and dividing the fluorescent material-containing film into a plurality of the fluorescent material-containing film pieces arranged in a matrix manner, using a thick dicing blade;

an A2 step of transferring the plurality of the fluorescent material-containing film pieces arranged in a matrix manner, onto a worksheet;

an A3 step of potting the silicon resin on each of the plurality of the fluorescent material-containing film pieces and die-bonding the semiconductor light emitting element thereon with the light extraction surface facing down, to form a double structure of the fluorescent material-containing film piece and the semiconductor light emitting element;

an A4 step of attaching a band-shaped spacer for reflection wall onto the worksheet so as to surround a region where a plurality of the double structures arranged in a matrix manner are present, with a single passage left, and placing a top sheet on the spacer for reflection wall and the semiconductor light emitting element such that the top sheet is in close contact with an upper surface of the spacer for reflection wall and the bump mounting surface of the bump at which the semiconductor light emitting element is mounted on the external substrate, to form a hermetic space which is hermitically sealed except for the single passage;

an A5 step of injecting a reflection wall resin for forming the reflection wall into the hermetic space formed in the A4 step through the single passage and curing the reflection wall resin to cover a surface other than the light exit surface of the double structure and the bump mounting surface with the reflection wall; and

an A6 step of peeling the worksheet and the top sheet, attaching the double structures connected to each other via the reflection wall and formed into a plate shape onto a dicing sheet, and dicing a center between the adjacent double structures with a dicing blade thinner than the thick dicing blade, into the individual light emitting devices.

5. The method for manufacturing the light emitting device according to claim 4, wherein the fluorescent material-containing film is manufactured by a process comprising:

a C1 step of attaching a closed band-shaped spacer for fluorescent material onto a thick release sheet such that the spacer for fluorescent material surrounds a film forming space for forming the fluorescent material-containing film;

a C2 step of potting a fluorescent material-containing silicon resin in which fluorescent material powder is dispersed, in the film forming space with a feeding mechanism;

a C3 step of filling the film forming space with the fluorescent material-containing silicon resin with a thickness equal to that of the spacer for fluorescent material; and

a C4 step of placing a thin release sheet on the film forming space, sandwiching the film forming space between smooth and high rigid plates via the thick release sheet and the thin release sheet, and conducting curing with a certain amount of pressure applied.

6. The method for manufacturing the light emitting device according to claim 5, wherein each of the worksheet, the spacer for reflection wall, the top sheet, and the spacer for fluorescent material is a base sheet which is made of a heat-resistant resin and one surface of which is coated with an ultraviolet-curable self-adhesive glue.

7. The method for manufacturing the light emitting device according to claim 6, wherein the reflection wall resin is injected by a process comprising:

a D1 step of irradiating a structure which has the single passage on the worksheet and forms the hermetic space formed in the A4 step, with ultraviolet light to cure the ultraviolet-curable self-adhesive glue in the structure;

a D2 step of placing the structure in a chamber which can be vacuumed, and vacuuming an inside of the chamber;

a D3 step of potting the reflection wall resin such that the reflection wall resin blocks the single passage in the structure placed in the chamber; and

a D4 step of causing an internal pressure of the chamber to gradually approach an atmospheric pressure to inject the reflection wall resin through the single passage into the hermetic space formed in the A4 step.

8. The method for manufacturing the light emitting device according to claim 4, wherein an E1 step of irradiating the fluorescent material-containing film piece from below the fluorescent material-containing film piece using a light emitter which emits light having the same wavelength as that of the semiconductor light emitting element, and measuring chromaticity, color temperature, or the like of light converted by the fluorescent material-containing film piece with a detector located above the light emitter, is added between the A2 step and the A3 step.

9. The method for manufacturing the light emitting device according to claim 8, wherein the silicon resin used in the A3 step is a silicon resin in which fluorescent material powder or a pigment for correcting chromaticity or color temperature is dispersed on the basis of measurement data in the E1 step.

10. The method for manufacturing the light emitting device according to claim 6, wherein the surface of the base sheet being the worksheet or the top sheet and made of the heat-resistant resin which surface is coated with the ultraviolet-curable self-adhesive glue is roughened in a form of ground glass such that bonding strength with the glue is increased.

13. The light emitting device according to 2, wherein a material of the fluorescent material-containing film piece is a material obtained by dispersing powder of several types of fluorescent materials in a silicon resin, and a material of the reflection wall is a material obtained by dispersing titanium oxide fine powder in a silicon resin.

14. The method for manufacturing the light emitting device according to claim 5, wherein an E1 step of irradiating the fluorescent material-containing film piece from below the fluorescent material-containing film piece using a light emitter which emits light having the same wavelength as that of the semiconductor light emitting element, and measuring chromaticity, color temperature, or the like of light converted by the fluorescent material-containing film piece with a detector located above the light emitter, is added between the A2 step and the A3 step.

15. The method for manufacturing the light emitting device according to claim 6, wherein an E1 step of irradiating the fluorescent material-containing film piece from below the fluorescent material-containing film piece using a light emitter which emits light having the same wavelength as that of the semiconductor light emitting element, and measuring chromaticity, color temperature, or the like of light converted by the fluorescent material-containing film piece with a detector located above the light emitter, is added between the A2 step and the A3 step.

16. The method for manufacturing the light emitting device according to claim 7, wherein an E1 step of irradiating the fluorescent material-containing film piece from below the fluorescent material-containing film piece using a light emitter which emits light having the same wavelength as that of the semiconductor light emitting element, and measuring chromaticity, color temperature, or the like of light converted by the fluorescent material-containing film piece with a detector located above the light emitter, is added between the A2 step and the A3 step.

11. A light emitting device wherein

on a semiconductor light emitting element which emits blue light, purple light, or ultraviolet light, has two opposed principal surfaces one of which is a light extraction surface and another of which is an electrode-formed surface, and has a bump on the electrode-formed surface, a fluorescent material-containing film piece which has two opposed principal surfaces each of which is the same in size as or larger in size than the light extraction surface, one of which is a light entrance surface, and another of which is a light exit surface is overlaid such that the light extraction surface is opposed to the light entrance surface, and

an exposed surface other than the electrode-formed surface of the semiconductor light emitting element (including a surface of the bump) and the light exit surface of the fluorescent material-containing film piece (or the light exit surface of the fluorescent material-containing film piece and a bump mounting surface of the bump at which the semiconductor light emitting element is mounted on an external substrate) and a portion, at the light exit surface side, of a side surface of the fluorescent material-containing film piece is covered with a reflection wall, and the bump mounting surface or an electrode on the electrode-formed surface protrudes from a lowest bottom surface of the reflection wall.

12. A light emitting device wherein

on a semiconductor light emitting element which has two opposed principal surfaces one of which is a light extraction surface and another of which is an electrode-formed surface and has a bump on the electrode-formed surface, a transparent film piece which has two opposed principal surfaces each of which is the same in size as or larger in size than the light extraction surface, one of which is a light entrance surface, and another of which is a light exit surface is overlaid such that the light extraction surface is opposed to the light entrance surface, and

an exposed surface other than the electrode-formed surface of the semiconductor light emitting element (including a surface of the bump) and the light exit surface of the transparent film piece or an exposed surface other than the light exit surface of the transparent film piece and a bump mounting surface of the bump at which the semiconductor light emitting element is mounted on an external substrate is covered with a reflection wall, and the bump mounting surface or an electrode on the electrode-formed surface protrudes from a lowest bottom surface of the reflection wall.