Light emitting device with tension relaxation
View Patent ↗A light emitting device is provided, comprising a light emitting diode 10 , where the light emitting surface 11 thereof is bound to an optical element 13 by means of a bonding material 12 comprising a phosphate glass or an oxide glass having Tg<250° C. In operation of the device, when the temperature approaches or exceeds Tg of the bonding material, the bonding material gets fluidic and can thus relax any thermally induced stresses between the light emitting diode and the optical element.
1. A light emitting device comprising at least one light emitting diode and at least one optical element bonded to a light emitting surface of said at least one light emitting diode by means of a bonding material comprising a first luminescent compound and a glass material comprising a tin phosphate glass and an oxide glass and having a T g of up to 250° C., said oxide glass being selected from the group consisting of tungsten/tellurium oxide glass, sodium/zinc/tellurium oxide glass, barium/zinc/tellurium oxide glass and mixtures thereof.
2. A light emitting device according to claim 1 , wherein said at least one light emitting diode is a flip-chip type light emitting diode.
3. A light emitting device according to claim 1 , wherein said optical element comprises an inorganic material.
4. A light emitting device according to claim 1 , wherein said optical element comprises a second luminescent compound.
5. A method for the manufacture of a light emitting device, comprising
providing at least one light emitting diode and at least one optical element;
arranging a bonding material comprising a first luminescent compound and a glass material, comprising a tin phosphate glass and an oxide glass, and having a T g of up to 250° C., said oxide glass being selected from the group consisting of tungsten/tellurium oxide glass, sodium/zinc/tellurium oxide glass, barium/zinc/tellurium oxide glass and mixtures thereof, on a light emitting surface of said at least one light emitting diode and/or on a surface of said at least one optical element;
placing said at least one optical element on said light emitting surface of said at least one light emitting diode with said bonding material there between to form an assembly; and
heating said bonding material at a temperature above the T g thereof to bond said at least one optical element to said at least one light emitting diode.
6. A method according to claim 5 , wherein said heating is performed while compressing said assembly.
7. A method according to claim 5 , wherein said optical element comprises an inorganic material.
8. A method according to claim 5 , wherein said optical element comprises a second luminescent compound.