TW201721908A - Surface emitter with light-emitting area equal to the LED top surface - Google Patents

Abstract

A method includes forming a wavelength converting layer on a first support, placing light-emitting diodes (LEDs), with their top-emitting surfaces facing down, on the wavelength converting layer, curing the wavelength converting layer so the top-emitting surfaces of the LEDs adhere to the wavelength converting layer, singulating the LEDs by cutting the cured wavelength converting layer between the LEDs, wherein after said singulating each LED has a wavelength converter that exactly overlaps or slightly extends beyond a top-emitting surface of the LED, forming a reflective layer over and in-between the LEDs, curing the reflective layer, wherein the cured reflective layer has a hardness and an abrasion rate greater than the cured wavelength converting layer, and removing a top portion of the cured reflective layer to expose the LEDs.

Description

Surface emitter having a light-emitting area equal in size to the upper surface of the light-emitting diode

This invention relates to semiconductor light emitting diodes (LEDs) and, more particularly, to upper emitting LED packages.

The small LED package offers greater design flexibility in many applications, including camera flash and automotive lighting. For upper emissive LEDs, it may be desirable to minimize the size of the upper emissive region and the overall height of the package.

In one or more examples of the present invention, a method includes: forming a wavelength conversion layer on a support; placing an emission surface on a light emitting diode (LED) face down and placing the LEDs on the wavelength conversion layer Curing the wavelength conversion layer such that the upper emission surfaces of the LEDs are adhered to the wavelength conversion layer; singulating the LEDs by cutting the cured wavelength conversion layer between the LEDs, wherein After singulation, each LED has a wavelength converter that precisely overlaps or slightly extends beyond the emitting surface of the LED; a reflective layer is formed over and in the middle of the LED; the reflective layer is cured, wherein The cured reflective layer has a hardness greater than one of the cured wavelength converting layers and an abrasion rate; and an upper portion of the cured reflective layer is removed to expose the LEDs.

CROSS-REFERENCE TO RELATED APPLICATIONS RELATED APPLICATIONS RELATED APPLICATIONS RELATED APPLICATIONS RELATED APPLICATIONS RELATED APPLICATIONS s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s The priority of the present application is hereby incorporated by reference in its entirety. 1 is a side cross-sectional view of one of an emissive light emitting diode (LED) unit or package 100 in one of the examples of the present invention. The LED unit 100 includes an LED 102 having a contact 104 on a bottom surface, a reflector 106 on a side surface of the LED, and a wavelength converter 108 above the LED and the upper portion of the reflector. It should be noted that the use of the term "above" includes one element directly above the other element. LED 102 is a five-sided transmitter. Reflector 106 contains primary light that is emitted by the sidewalls of LEDs 102 and that redirects the primary light to the upper surface of the LEDs. Wavelength converter 108 converts portions of the primary light into secondary light of a different wavelength that is combined with the remainder of the primary light to produce a desired color. Typically, reflector 106 is molded around LED 102 and the upper surface is then coated with wavelength converter 108. The wavelength converter 108 can be a layer having a phosphor layer in a first fluorenone followed by a layer of titanium oxide (TiOx) in a second fluorenone. The LED unit 100 is inefficient due to the fact that a portion of the light (e.g., 10%) is horizontally guided along the wavelength converter 108. The LED unit 100 is also large due to the extension of the wavelength converter 108 to cover the reflector 106, which causes the emission area above the LED unit to be much larger than the upper surface of the LED 102. 2 is a side cross-sectional view of one of the emissive LED units or packages 200 in one of the examples of the present invention. The LED unit 200 includes an LED 102 having a contact 104 on a bottom surface, a wavelength converter 206 above the LED, a protective glass plate 208 above the wavelength converter, and side surfaces of the LED, the wavelength converter, and the glass plate. A reflector 210. Wavelength converter 206 converts the portion of the primary light emitted by LED 102 into secondary light of a different wavelength that is combined with the remainder of the primary light to produce a desired color. Reflector 210 contains light emitted by the sidewalls of LEDs 102 and redirects the light to the upper surface of the LEDs. Typically, a wavelength converter 206 is formed over the glass sheet 208 and this interlayer is attached to the LEDs 102. The wavelength converter 206 can be a phosphor ceramic plate or have a phosphor layer in a first fluorenone followed by a layer of a TiOx layer in a second fluorenone. Next, the reflector 210 is molded over the entire area and excess material is removed to open the surface of the wavelength converter 206, which is protected by the glass sheet 208 during removal of excess material. The LED unit 200 is high due to the use of the glass plate 208 as a protective layer to prevent damage to the wavelength converter 206 during package manufacture. 3 is a side cross-sectional view of one of the LED units or packages 300 in an example of the present invention. The LED unit 300 includes an LED 102 having a contact 104 on a bottom surface, a wavelength converter 306 above the LED, and a reflector 308 on the side surface of the LED and the wavelength converter. LED 102 can be a surface mount device (SMD). The LED 102 can have a height from 50 micrometers (μm) to 400 micrometers (μm). The wavelength converter 306 forms a light emitting region of the LED unit 300. The wavelength converter 306 can precisely overlap or extend slightly beyond the upper surface of the LED 102, thereby causing the emission area above the LED unit 300 to be smaller than the emission area above the LED unit 100 (Fig. 1). The suspension of the wavelength converter 306 beyond the upper surface of the LED 102 depends on the accuracy of the single granulation machine used to separate the adjacent LEDs 102 as described later. In some examples, the suspension is in the range of from 0 μm to 50 μm. The side surface of the wavelength converter 306 is covered by the reflector 308 such that light cannot exit horizontally through the wavelength converter, thereby making the LED unit 300 more efficient than the LED unit 100. The wavelength converter 306 can be a layer having a phosphor layer in a first fluorenone followed by a layer of TiOx (e.g., TiO ₂ ) in a second fluorenone, wherein the fluorenone can be an elastomer or a resin. The first layer may include from 1% to 80% by weight of the phosphor, and the second layer may include from 0.05% to 10% by weight of TiOx. The phosphor layer in the first fluorenone may be 35 μm to 150 μm (for example, 87 μm) thick, and the TiOx layer in the second fluorenone may be about 30 μm to 90 μm (for example, 50 μm) thick. Instead of TiOx, the second layer may be zirconia (ZrOx) in an anthrone. Reflector 308 is formed by depositing a thick layer of reflective material over wavelength converter 306 on LED 102 and removing excess material from the upper surface to expose the wavelength converter. The reflective material has a hardness greater than one of the wavelength converting materials, and thus the reflective material also has an abrasion rate that is greater than one of the wavelength converting materials. By utilizing the difference in hardness and abrasion rate, excess reflective material can be removed through a sandblasting process without damaging the wavelength converting material, thereby eliminating the need for a protective glass sheet and making LED unit 300 shorter than LED unit 200 (FIG. 2). The reflective material can have a reflectivity of more than 90%. The reflective material can have a hardness that is one hundred times the hardness of the wavelength converting material, and the reflective material can have an abrasion rate that is one ten times the abrasion rate of the wavelength converting material. For example, the reflective material may be one of a ketone molding compound (SMC) having a hardness of 7 gigapascal (GPa), and the wavelength converting material may be a laminate having a hardness of 60 megapascal (MPa). (described above), and the reflective material can have an abrasion rate of 60 μm per pass at 30 psi, while the wavelength converting material can have an abrasion of 0.05 μm per pass at 30 psi. rate. The SMC may comprise from about 82% to 87% yttrium oxide (SiOx) and from 13% to 18% TiOx. Alternatively, the SMC can be SiOx and ZrO. 4 is a flow diagram of a method 400 for fabricating an LED unit 300 in an example of the present invention. Method 400 can begin at block 402. In block 402, a wavelength conversion layer 502 is formed on a support member 504 as shown in view 506 of FIG. The wavelength converting layer 502 can be a layer having one of the first fluorenone TiOx layer followed by one of the phosphor layers in the second fluorenone above the first layer. The support member 504 can be an adhesive tape supported by a metal frame. Referring again to FIG. 4, block 402 may be followed by block 404. In block 404, as shown in view 508 of FIG. 5-1, the LEDs 102 (labeled only one) are placed with the emission surface facing down and the bottom contact surface facing up while the LEDs are placed on the wavelength conversion layer 502. . The LEDs 102 can be heated to adhere to the wavelength conversion layer 502, or the LEDs can be at room temperature during attachment, and the wavelength conversion layer 502 can be heated. Referring again to FIG. 4, block 404 may be followed by block 406. In block 406, the wavelength conversion layer 502 is cured to adhere the emissive surface above the LED 102 to the wavelength conversion layer. Block 406 may be followed by block 408. In block 408, as shown in view 510 of Figure 5-1, the LEDs 102 are singulated by cutting the cured wavelength converting layer 502 (view 508 in Figure 5-1) between the LEDs. After singulation, each LED 102 has a wavelength converter 306 that exceeds one of its upper emitting surfaces. As can be seen, the wavelength converter 306 constitutes a light emitting region of the LED unit 300 that is substantially the same size as the emitting surface above the LED 102. Referring again to FIG. 4, block 408 may be followed by block 410. In option block 410, as shown in view 514 of Figure 5-1, the bottom contact surface of the LED 102 faces downward and the upper emission surface faces up and the LEDs 102 are brought to the adhesive side of a support member 512. on. The LEDs 102 can be transferred from the support 504 to the support 512. The support member 512 can be an adhesive tape on a metal frame. Referring again to FIG. 4, block 410 is selected and block 412 is followed. At block 412, an optically reflective layer 516 is formed over and in the middle of LED 102, as shown in view 518 of FIG. Referring again to FIG. 4, block 412 may be followed by block 414. In block 414, the reflective layer 516 is cured to adhere the LEDs 102 to the reflective layer. The cured reflective material has a hardness greater than one of the cured wavelength converting materials and an abrasion rate. Block 414 may be followed by block 416. In block 416, as shown in view 520 of FIG. 5-1, an upper portion of reflective layer 516 (view 518 in FIG. 5-1) is removed to expose LEDs 102. For example, the upper portion of the reflective layer 516 is removed downward to the upper portion of the wavelength converter 306 (only one is labeled). The upper portion of the reflective layer 516 can be removed by sand blasting. As can be seen, the LED unit 300 does not have any protective glass sheets that would otherwise increase the height of the unit. Referring again to FIG. 4, block 416 may be followed by block 418. In block 418, as shown in view 522 of Figure 5-2, the LED 102 is singulated to have a reflector by cutting the cured reflective layer 516' (view 520 in Figure 5-1) between the LEDs. LED unit 300 of 308. As can be seen, the reflector 308 covers the side surface of the wavelength converter 306 to prevent any light from escaping laterally along the wavelength converter. Referring again to FIG. 4, block 418 may be followed by block 420. In block 420, as shown in view 524 of Figure 5-2, LED unit 300 (labeled only one) is disengaged from support 512 (view 522 in Figure 5-2). For example, the LED unit 300 is thermally released from the support 512. 6 is a flow diagram of a method 600 for fabricating an LED unit 300 in an example of the present invention. Method 600 can begin at block 602. In block 602, as shown in view 708 of FIG. 7, wavelength conversion layer 502 is formed on support 512. Referring again to FIG. 6, block 602 may be followed by block 604. In block 604, as shown in view 708 of FIG. 7, the LEDs 102 (marked only one) are placed with the emission surface facing down and the bottom contact surface facing up and the LEDs 102 are placed on the wavelength conversion layer 502. The LEDs 102 can be heated to adhere to the wavelength conversion layer 502, or the LEDs can be at room temperature during attachment, and the wavelength conversion layer 502 can be heated. Referring again to FIG. 6, block 604 may be followed by block 606. In block 606, the wavelength conversion layer 502 is cured to adhere the emissive surface above the LED 102 to the wavelength conversion layer. Block 606 may be followed by block 608. In block 608, LED 102 is singulated by cutting the cured wavelength converting layer 502 (view 708 in FIG. 7) between the LEDs as shown in view 710 of FIG. After singulation, each LED 102 has a wavelength converter 306 (marked only one) above its upper emitting surface. As can be seen, the wavelength converter 306 constitutes a light emitting region of the LED unit 300 that is substantially the same size as the emitting surface above the LED 102. Referring again to FIG. 6, block 608 may be followed by block 612. In block 612, as shown in view 718 of FIG. 7, an optically reflective layer 516 is formed over and in the middle of the LEDs 102. Referring again to FIG. 6, block 612 may be followed by block 614. In block 614, the reflective layer 516 is cured to adhere the LEDs 102 to the reflective layer. The cured reflective material has a hardness greater than one of the cured wavelength converting materials and an abrasion rate. Block 614 may be followed by block 616. In block 616, as shown in view 720 of FIG. 7, one of the upper portions of reflective layer 516 (view 718 in FIG. 7) is removed to expose LEDs 102. For example, the upper portion of the reflective layer 516 is removed down to the contacts 104 on the bottom contact surface of the LED 102 (only two are labeled). The upper portion of the reflective layer 516 can be removed by sandblasting or polishing. As can be seen, the LED unit 300 does not have any protective glass sheets that would otherwise increase the height of the unit. Referring again to FIG. 6, block 616 may be followed by block 618. In block 618, as shown in view 722 of FIG. 7, LED 102 is singulated into LED units having reflectors 308 by cutting cured reflective layer 516' (view 720 in FIG. 7) between the LEDs. 300. As can be seen, the reflector 308 covers the side surface of the wavelength converter 306 to prevent any light from escaping laterally along the wavelength converter. Referring again to FIG. 6, block 618 may be followed by block 620. In block 620, the LED unit 300 is released from the support 512. For example, the LED unit 300 is thermally released from the support 512. Various other adaptations and combinations of the features of the disclosed embodiments are within the scope of the invention. The scope of the following patent application covers many embodiments.

100‧‧‧Light Emitting Diode (LED) Units / Packages
102‧‧‧Lighting diode (LED)
104‧‧‧Contacts
106‧‧‧ reflector
108‧‧‧wavelength converter
200‧‧‧Light Emitting Diode (LED) Units / Packages
206‧‧‧wavelength converter
208‧‧‧protective glass
210‧‧‧ reflector
300‧‧‧Light Emitting Diode (LED) Unit / Package
306‧‧‧wavelength converter
308‧‧‧ reflector
400‧‧‧ method
402‧‧‧ square
404‧‧‧ square
406‧‧‧ square
408‧‧‧ squares
410‧‧‧ square
412‧‧‧ square
414‧‧‧ squares
416‧‧‧ square
418‧‧‧ square
420‧‧‧ square
502‧‧‧wavelength conversion layer
504‧‧‧Support
506‧‧‧ view
508‧‧‧ view
510‧‧ view
512‧‧‧Support
514‧‧‧ view
516‧‧‧Optical reflective layer
516'‧‧‧cured reflective layer
518‧‧‧ view
520‧‧‧ view
522‧‧‧ view
524‧‧‧ view
600‧‧‧ method
602‧‧‧ square
604‧‧‧ square
606‧‧‧ square
608‧‧‧ square
612‧‧‧ square
614‧‧‧ square
616‧‧‧ squares
618‧‧‧ square
620‧‧‧ square
708‧‧ view
710‧‧ view
718‧‧ view
720‧‧‧ view
722‧‧‧ view

In the drawings: Figure 1 is a side cross-sectional view of an emissive LED unit or package having one of a wavelength converter in an example of the present invention, the wavelength converter extending to the edge of the unit; A side cross-sectional view of an emissive LED unit or package having one of the protective glass sheets above a wavelength converter in an example of the present invention; FIG. 3 is an example of the present invention having an upper surface with an LED, etc. A side cross-sectional view of one of the emissive LED units or packages on one of the illuminating regions of size; FIG. 4 is a flow diagram of one of the methods used to fabricate the LED unit of FIG. 3 in an example of the present invention; 1 and FIG. 5-2 are side cross-sectional views showing a process of manufacturing the LED unit of FIG. 3 using the method of FIG. 4 in the example of the present invention; FIG. 6 is used to manufacture FIG. 3 in the example of the present invention. A flow chart of one of the methods of the LED unit; and FIG. 7 is a side cross-sectional view showing a process of manufacturing the LED unit of FIG. 3 using the method of FIG. 6 in an example of the present invention. The same element symbols are used in the different figures to indicate similar or identical elements.

102‧‧‧Lighting diode (LED)

104‧‧‧Contacts

300‧‧‧Light Emitting Diode (LED) Unit / Package

306‧‧‧wavelength converter

308‧‧‧ reflector

Claims (14)

A method comprising: forming a wavelength conversion layer on a support member; placing an emission surface of the light emitting diode (LED) face down and a bottom contact surface facing upward and placing the LEDs on the wavelength conversion layer; Curing the wavelength conversion layer to adhere it to the upper emission surfaces of the LEDs; singulating the LEDs by cutting the cured wavelength conversion layer between the LEDs, wherein after the singulation Each LED has a wavelength converter that precisely overlaps or extends slightly beyond the emission surface of the LED; an optical reflective layer is formed over and in the middle of the LED; the reflective layer is cured; and the An upper portion of the reflective layer is cured to expose the LEDs. The method of claim 1, further comprising, after singulating the LEDs and before forming the optical reflective layer: placing the bottom contact surfaces of the LEDs facing down and placing the LEDs to another support member The removing the upper portion of the cured reflective layer includes: removing the cured reflective layer downward to the wavelength converters on the upper emitting surfaces. The method of claim 1, wherein removing the upper portion of the cured reflective layer comprises: removing the cured reflective layer down to contacts on the bottom contact surfaces. The method of claim 2 or 3, further comprising, after the removing the upper portion of the cured reflective layer: singulating the LEDs into LED units by cutting the cured reflective layer between the LEDs Each of the LED units has a reflector on its side surface of the wavelength converter and the LED. The method of claim 4, further comprising: releasing the LED units from the second support after singulating the LEDs into LED units. The method of claim 2 or 3, wherein the cured reflective layer has a hardness greater than a hardness of the cured wavelength conversion layer and an abrasion rate. The method of claim 6, wherein removing the upper portion of the cured reflective layer comprises: sandblasting or polishing the reflective layer. The method of claim 1, wherein the wavelength conversion layer comprises a laminate comprising a phosphor layer in the first fluorenone and a titanium oxide layer in the second fluorenone. The method of claim 1, wherein the reflective layer comprises titanium oxide in an anthrone. The method of claim 1, wherein the wavelength converter is suspended from 0 micrometers to 50 micrometers above the upper emitting surface of the LED. A light emitting diode (LED) unit comprising: an LED having an upper emitting surface; a wavelength converter that precisely overlaps or extends slightly beyond the upper emitting surface; and a reflector, It surrounds the wavelength converter and a side surface of the LED, wherein the reflector includes a hardness and an abrasion rate higher than one of the wavelength converters. The LED unit of claim 11, wherein the wavelength conversion layer comprises a layer comprising a phosphor layer in a first fluorenone and a titanium oxide layer in a second fluorenone above the first layer. The LED unit of claim 11, wherein the reflector comprises titanium oxide in an anthrone. The LED unit of claim 11, wherein the wavelength converter is suspended from 0 micrometers to 50 micrometers above the upper emitting surface of the LED.