Multichip light emitting diode (led) and method of manufacture

Abstract

The present invention provides a multichip LED and method of manufacture in which white light is produced. A plurality of electrically interconnected LED chips is selected for conversion of light to white light. The LED chips comprise: a blue LED chip, a red LED chip, a green LED chip, and a target LED chip whose light output is converted to white light. A wavelength of a light output by one or more of the plurality of chips will be measured. Based on the wavelength measurement, a conformal coating is applied to the one or more of the LED chips. The conformal coating has a phosphor ratio that is based on the wavelength. The phosphor ratio is comprised of at least one of the following colors: yellow, green, or red. Using the conformal coating, the light output of the target LED is then converted to white light.

What is claimed is: 
     
         1 . A method for manufacturing a multichip light emitting diode (LED chip), comprising:
 providing a plurality of LED chips in electrical contact with each other;   applying a conformal coating to at least one of the plurality of LED chips, the conformal coating having a phosphor ratio that is based on a previous measurement; and   converting a light output of a target LED chip of the plurality of LED chips to white light using the conformal coating.   
     
     
         2 . The method of  claim 1 , the previous measurement comprising a measurement of a wavelength of the light output by the plurality of LED chips. 
     
     
         3 . The method of  claim 1 , the plurality of LED chips comprising:
 a blue LED chip;   a red LED chip;   a green LED chip; and   the target LED chip whose light output is converted to white light.   
     
     
         4 . The method of  claim 1 , further comprising isolating an area of the plurality of LED chips to which the conformal coating is applied. 
     
     
         5 . The method of  claim 4 , the area being isolated using paraffin wax. 
     
     
         6 . The method of  claim 4 , the area being isolated using a silk screen. 
     
     
         7 . The method of  claim 4 , the area being isolated using a photo resist. 
     
     
         8 . The method of  claim 1 , the conformal coating having a phosphor ratio comprised of at least one of the following colors: yellow, green, or red. 
     
     
         9 . The method of  claim 1 , the plurality of LED chips being disposed on a wafer, the conformal coating being applied to the wafer.