Led reflective package
An LED package which employs a high temperature plastic or polymeric material which is compatible with widely used gold-tin eutectic solder and which can replace the higher cost ceramic used in conventional LED packages. The novel LED package has a high thermal conductivity substrate, a high reflectivity for visible light and/or UV light, and good aging properties. The high temperature material is a high temperature liquid crystal polymer (LCP) having a melting temperature greater than about 340° C. and has small filler particles near the surface, the particles having a refractive index greater than about 2.0, and a size range of about 0.2 to 0.3 microns. For an LED package which is reflective to UV light, a UV stabilizer can be included in the plastic material to improve reflectivity in the ultraviolet spectrum and to protect from UV degradation of the plastic material which can be caused by UV light emitted by some LEDs.
1 . A light emitting diode (LED) package comprising:
a housing of a high temperature plastic material having a top surface, a bottom surface and a cavity, and the cavity sized to accommodate at least one LED;
a substrate attached to the bottom surface of the housing and adapted for attaching at least one LED;
the high temperature plastic material having a melting temperature greater than about 340° C., and a plurality of filler particles; and wherein
the top surface of the housing is adapted to mount a lens.
2 . For use in a package containing one or more light emitting diodes mounted on a substrate, a housing having one or more reflective surfaces and comprising:
a body of high temperature polymeric material having a melting temperature greater than about 340° C.;
a cavity configured to surround the one or more light emitting diodes mounted on the substrate;
the cavity having one or more reflective surfaces angled with respect to the substrate by less than about 20° to reflect light from the one or more light emitting diodes; and
the body having a first mounting surface for mounting the body onto the substrate, and having a second mounting surface for attaching a lens through which light from the one or more light emitting diodes can be transmitted.
3 . The invention of claim 2 wherein the body of high temperature polymeric material has a composition which includes a chemical group selected from the chemical groups consisting of: hydroquinine (HQ), 4,4 bisphenol (BP) bis(4-hydroxylphenyl ether) (POP), terephalic acid (TPA), 2,6 naphalene dicarboxylic acid (NPA), 4,4 benzoic acid (BB), 4-hydrosybenzoic acid (HBA), 6-hydroxy-2-naptholic acid (HNA).
4 . The invention of claim 2 wherein the body of high temperature polymeric material has a filler in the range of 10-60%.
5 . The invention of claim 4 wherein the filler includes: T i O 2 , Z n O, and glass.
6 . The invention of claim 5 wherein T i O 2 is present in the range of about 10-22%.
7 . The invention of claim 6 wherein Z n O is <1%.
8 . The invention of claim 5 wherein the T i O 2 is Rutile T i O 2 .
9 . The invention of claim 5 wherein the T i O 2 particles are in the range of 0.1-0.5 microns.
10 . The invention of claim 5 wherein the Z n O particles are <100 nm.
11 . The invention of claim 9 wherein the nano T i O 2 particles are <100 nm and less than 1% of the filler.
12 . The invention of claim 2 wherein the high temperature polymeric material has a coefficient of expansion in the range of about 5 ppm/° C.-30 ppm/° C.
13 . The invention of claim 2 wherein the high temperature polymeric material has a coefficient of expansion in the range of about 10-20 ppm/° C.
14 . The invention of claim 2 wherein the substrate material has a thermal conductivity which is >300 W/mK.
15 . The invention of claim 2 wherein the substrate material is an alloy which contains a minimum of 50% copper.
16 . The invention of claim 15 wherein the substrate material has a preferred copper content of >99.0% Cu.