Singulaton of light emitting devices before and after application of phosphor
View Patent ↗A two-stage singulation process is used in the fabrication of phosphor coated light emitting elements. Prior to the application of the phosphor coating, the individual light emitting elements are singulated using a laser dicing process ( 130 ); after application of the phosphor coating ( 150 ), the phosphor coated light emitting elements are singulated using a mechanical dicing process ( 180 ). Before laser dicing of the light emitting elements, the wafer is positioned on a piece of dicing- or die-attach-tape held by a frame; after laser dicing, the tape is stretched ( 140 ) to provide space between the individual light emitting elements that allows for the wider kerf width of the subsequent mechanical dicing ( 180 ) after application of the phosphor coating ( 150 ).
1. A structure comprising:
a stretchable film;
a plurality of light emitting elements situated on un-stretched segments of the stretchable film, each light emitting element comprising:
a top surface and a bottom surface opposite the top surface, the bottom surface being situated on an un-stretched segment of the stretchable film; and
one or more side surfaces connecting the top surface to the bottom surface;
a plurality of streets between the light emitting elements, the streets being situated on stretched segments of the stretchable film, the stretched segments being in a state of greater strain than the un-stretched segments, the stretched segments having a strain greater than 5;
a filler material that fills the plurality of streets from the bottom surface and extends only partly up along the one or more coating side surfaces but not completely along the one or more side surfaces: and
a continuous wavelength conversion coating that extends over the light emitting elements and in the streets between the light emitting elements, such that; the wavelength conversion coating is in contact with the filler material at the base of the wavelength conversion coating, has a substantially flat top surface, and comprises side surfaces shaped by at least two side surfaces of two different light emitting elements.
2. The structure of claim 1 , including a glass substrate that is attached atop the continuous wavelength conversion coating.
3. The structure of claim 1 , wherein a width of the streets is at least 100 um.
4. The structure of claim 1 , wherein the light emitting elements are fabricated from a single wafer having a first area before being diced into the light emitting elements, the bottom surface of each light emitting element has a second area, and the sum of second areas of the light emitting elements and the first area provide a wafer utilization that is equal to or greater than 88%.