Forming a multicolor phosphor-converted LED array
A phosphor carrier assembly includes a substrate, a thermal or UV activated release adhesive, a layer containing a pixelated phosphor array, and a partially cured or highly viscous adhesive. The phosphor pixels on the carrier are typically all of the same color. In formation of a phosphor converted LED array the phosphor pixels on the carrier assembly are aligned with and placed in contact with corresponding LED pixels in an array of pixelated LED dice. Selected phosphor pixels on the carrier assembly may then be attached to corresponding LED pixels, and released from the substrate, by powering (activating) the corresponding LED pixels to heat the selected phosphor pixel to a temperature that releases the thermal release adhesive and that cures or partially cures the adhesive on the selected phosphor pixels in contact with the corresponding LED pixels.
1. A method for manufacturing a phosphor converted LED array, the method comprising:
positioning an LED array comprising LED pixels and a phosphor structure comprising phosphor pixels with the LED pixels of the LED array aligned with and in contact with corresponding ones of the phosphor pixels of the phosphor structure; and
electrically operating selected ones of the LED pixels to emit light and to heat the corresponding phosphor pixels to a temperature that bonds each of the selected LED pixels to the corresponding phosphor pixel.
2. The method of claim 1 wherein all of the phosphor structure pixels of the phosphor structure are of a first color, the method further comprising:
positioning the LED array and a second phosphor structure comprising phosphor pixels of a second color different from the first color with LED pixels of the LED array that are not bonded to a phosphor pixel of the first color aligned with and in contact with corresponding ones of the phosphor pixels of the second phosphor structure; and
electrically operating selected ones of the LED pixels to emit light and to heat their corresponding phosphor pixels of the second phosphor structure to a temperature that bonds each of the selected LED pixels to the corresponding phosphor pixel of the second phosphor structure.
3. The method of claim 1 wherein the phosphor pixels comprise material selected from a group consisting of phosphor/silicone, ceramic phosphor, phosphor in glass, and phosphor on glass.
4. The method of claim 1 , wherein the phosphor structure comprises a substrate and surfaces of the phosphor pixels opposite from the LED array are attached to the substrate by a UV releasable adhesive, and operating the selected ones of the LED pixels to emit UV light releases the corresponding phosphor pixels from the substrate.
5. The method of claim 4 , comprising removing from the LED array the phosphor structure substrate and phosphor pixels not released from the substrate.
6. The method of claim 1 , wherein the phosphor structure comprises a substrate and surfaces of the phosphor pixels opposite from the LED array are attached to the substrate by a thermally releasable adhesive, and operating the selected ones of the LED pixels to emit light heats the corresponding phosphor pixels to a temperature that releases the corresponding phosphor pixels from the substrate.
7. The method of claim 6 , comprising removing from the LED array the phosphor structure substrate and phosphor pixels not released from the substrate.
8. The method of claim 6 wherein the substrate includes a PET carrier.
9. The method of claim 6 wherein electrically operating the selected ones of the LED pixels to emit light heats the thermally releasable adhesive to a temperature of 150 C to 220 C.
10. The method of claim 1 wherein:
the phosphor structure comprises a substrate, a releasable adhesive coating a surface of the substrate, a phosphor layer disposed on the releasable adhesive coating and attached by the releasable coating to the substrate, and a thermally activated adhesive disposed on a surface of the phosphor layer opposite from the releasable adhesive; and
electrically operating the selected ones of the LED pixels to emit light heats the thermally activated adhesive disposed on the corresponding phosphor pixels to a temperature that cures the thermally activated adhesive to bond the selected LED pixels to the corresponding phosphor pixels.
11. The method of claim 10 wherein electrically operating the selected ones of the LED pixels to emit light heats the thermally activated adhesive disposed on the corresponding phosphor pixels to a temperature of 100 C to 150 C.
12. The method of claim 10 wherein the thermally activated adhesive includes a thermally activated silicone adhesive.
13. The method of claim 10 wherein the thermally activated adhesive includes a thermally activated epoxy adhesive.
14. The method of claim 10 wherein the thermally activated adhesive has a refractive index of 1.41 to 1.6.
15. The method of claim 10 wherein the substrate includes a PET carrier.
16. The method of claim 10 , wherein the releasable adhesive is a thermally releasable adhesive, and electrically operating the selected ones of the LED pixels to emit light heats the thermally releasable adhesive to a temperature that releases the corresponding phosphor pixels from the substrate.
17. The method of claim 16 , wherein electrically operating the selected ones of the LED pixels to emit light heats the thermally releasable adhesive to a temperature of 150 C to 220 C.
18. The method of claim 16 , comprising removing from the LED array the substrate and phosphor pixels not released from the substrate.