Bridgelux Incorporated

Mike Kwon

Tao Tong

R Scott West

Michael Solomensky

Scott H West

Babak Imangholi

Gerry Keller

A method of fabricating a substrate free light emitting diode (LED), includes arranging LED dies on a tape to form an LED wafer assembly, molding an encapsulation structure over at least one of the LED dies on a first side of the LED wafer assembly, removing the tape, forming a dielectric layer on a second side of the LED wafer assembly, forming an oversized contact region on the dielectric layer to form a virtual LED wafer assembly, and singulating the virtual LED wafer assembly into predetermined regions including at least one LED. The tape can be a carrier tape or a saw tape. Several LED dies can also be electrically coupled before the virtual LED wafer assembly is singulated into predetermined regions including at the electrically coupled LED dies.

Substrate free LED package

Standardized photon building blocks are packaged in molded interconnect structures to form a variety of LED array products. No electrical conductors pass between the top and bottom surfaces of the substrate upon which LED dies are mounted. Microdots of highly reflective material are jetted onto the top surface. Landing pads on the top surface of the substrate are attached to contact pads disposed on the underside of a lip of the interconnect structure. In a solder reflow process, the photon building blocks self-align within the interconnect structure. Conductors in the interconnect structure are electrically coupled to the LED dies in the photon building blocks through the contact pads and landing pads. Compression molding is used to form lenses over the LED dies and leaves a flash layer of silicone covering the landing pads. The flash layer laterally above the landing pads is removed by blasting particles at the flash layer.

Packaging a substrate with an LED into an interconnect structure only through top side landing pads on the substrate

Packaging photon building blocks having only top side connections in a molded interconnect structure

Using compression molding to form lenses over LED arrays on a metal core printed circuit board leaves a flash layer of silicone covering the contact pads that are later required to connect the arrays to power. A method for removing the flash layer involves blasting particles of sodium bicarbonate at the flash layer. A nozzle is positioned within thirty millimeters of the top surface of the flash layer. The stream of air that exits from the nozzle is directed towards the top surface at an angle between five and thirty degrees away from normal to the top surface. The particles of sodium bicarbonate are added to the stream of air and then collide into the top surface of the silicone flash layer until the flash layer laterally above the contact pads is removed. The edge of silicone around the cleaned contact pad thereafter contains a trace amount of sodium bicarbonate.

Micro-bead blasting process for removing a silicone flash layer

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Pleasanton, CA, United States of America

Mike Kwon