METHOD AND SYSTEM FOR A LASER DIODE BAR ARRAY ASSEMBLY

Abstract
A laser diode array is formed on a heat sink having an insulating layer in which a plurality of grooves is formed through the ceramic layer and to or into the heat sink. A laser diode stack is soldered to the ceramic layer.
Description

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention can be better understood with reference to the following drawings, wherein like reference numerals designate like parts, and wherein:



FIGS. 1-3 are side elevational views of a laser diode bar array at various stages of assembly in accordance with a preferred embodiment of the invention;



FIG. 4 is a perspective view of a laser diode bar array in accordance with a preferred embodiment of the invention; and



FIG. 5 is a flowchart illustrating a method of providing a laser diode bar array assembly, in accordance with a preferred embodiment of the invention.





DETAILED DESCRIPTION


FIGS. 1-4 illustrate a first exemplary embodiment of the laser diode bar array 100 in various stages of assembly in accordance with the present invention. FIG. 1 is a side elevational view of the laser diode bar array 100 in an early stage of assembly, in accordance with the first exemplary embodiment of the invention. An electrical insulating layer 102 is mounted with solder 106 to a heat sink 104 formed of a conventionally used materials or alloys such as, copper, tungsten, a copper tungsten alloy, diamond, a composites containing diamond, graphite or berrillium oxide. The insulating layer 102 may be formed of a ceramic such as aluminum nitride or any other thermally conductive, electrically insulating material generally used for such purpose, (e.g., berrillium oxide, silicon, insulating composites containing diamonds) and is metallized on both faces. The solder 106 may be a hard, high-temperature solder, such as an AuGe or AuSn solder. However, other solders formed of, indium, lead, tin, gold or silver may also be used.



FIG. 2 is a side elevational view of a laser diode bar array 100 in a medial stage of assembly, in accordance with a first exemplary embodiment of the invention. FIG. 2 shows the insulating layer 102 is mounted to the heat sink 104 with solder 106. A plurality of grooves 108 are formed through the insulating layer 102 and the solder 106 to or partially into the heat sink 104. The grooves 108 are machined parallel to one another in a mesh pattern, e.g., using a dicer or the like, leaving a plurality of parallel streets 109.



FIG. 3 is a side elevational view of a laser diode bar array 100, in accordance with the first exemplary embodiment of the invention. A laser diode stack 110 formed by alternating spacers 112 and laser diode bars 114 is soldered to the top surface of the insulating layer 102 using a hard, high temperature solder which can be, but not necessarily, of same composition as the hard solder used to mount the insulating layer 102 to the heat sink 104. The spacers 112 preferably are formed of the same material similar as that used to form the heat sink 104, such as copper, tungsten, a copper tungsten alloy, diamond, composites containing diamond, graphite or berrillium oxide. As can be seen in FIG. 3, the laser diode bars 114 are centered over the grooves 108 while the spacers 112 are centered over and mounted to the streets 109. With this arrangement the individual streets are free to move with expansion and contraction of the heat sink, whereby the effects of stress due to mismatch in the coefficient of thermal expansion of the laser diode bar stack, the insulating layer, and the heat sink assembly may be minimized.


Minimizing the stress effect due to mismatch in the coefficients of thermal expansions also allows the use of hard solder between the laser diode stack 110 and the streets 109. The streets 109 thus provide both thermal conduction as well as electrical isolation between the individual laser diode bars 114. See also FIG. 4.



FIG. 5 is a flowchart illustrating a method of providing laser diode bar array assembly 100, in accordance with the first exemplary embodiment of the invention. It should be noted that any process descriptions or blocks in flow charts should be understood as representing modules, segments, portions of code, or steps that include one or more instructions for implementing specific logical functions in the process, and alternate implementations are included within the scope of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved.


As is shown by step 202, a metallized insulating layer 102 is joined to a heat sink 104 by a solder 106. A plurality of grooves 108 is formed through the metallized insulating layer 102 and solder 106 to or partially into the heat sink 104 (step 203). A laser diode stack 110 is formed of a plurality of spacers 112 and a plurality of laser diode bars 114 in alternating fashion (step 201), is then soldered onto the top of streets 109 of the metallized insulating layer 102 (step 204).


It is thus seen that the present invention provides a simple and low cost solution to minimizing the effects of stress induced due to mismatches in the coefficient of thermal expansion of components used in a diode bar array assembly.


It should be emphasized that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.

Claims
  • 1. A laser diode array comprising a heat sink;a metallized insulating layer mounted to the heat sink, said metallized insulating layer having a plurality of slots formed therein; anda laser diode bar array comprising a plurality of laser diode bars separated by electrically conducting spacers mounted to the insulating layer with the laser diode bars located over the slots.
  • 2. A laser diode array as claimed in claim 1, wherein the heat sink and the spacers are formed of the same material.
  • 3. A laser diode array as claimed in claim 1, wherein the heat sink and the spacers are formed from different materials that are closely matched for thermal expansion.
  • 4. The laser diode array as claimed in claim 2, wherein the slots are formed partially through the insulating layer.
  • 5. The laser diode array as claimed in claim 1, wherein the slots are formed through the insulating layer to or into the surface of the heat sink.
  • 6. The laser diode array as claimed in claim 1, wherein the insulating layer is mounted to the heat sink by solder.
  • 7. The laser diode array as claimed in claim 1, wherein the laser diode bar array is mounted to the insulating layer by solder.
  • 8. The laser diode array as claimed in claim 1, wherein the slots through the insulating layer are formed in place after the insulating layer is mounted to the heat sink.
  • 9. The laser diode array as claimed in claim 1, wherein the heat sink is formed of a material selected from the group consisting of copper, tungsten, a copper/tungsten alloy, diamond, composites containing diamond, graphite and beryllium oxide.
  • 10. The laser diode assembly as claimed in claim 6, wherein the insulating material comprises a ceramic, and the solder comprises a high temperature solder.
  • 11. The laser diode assembly as claimed in claim 6, wherein the insulating material comprises a composite material containing diamond, and the solder comprises a high temperature solder.
  • 12. The laser diode assembly as claimed in claim 10, wherein the high temperature solder comprises an AuGe solder or an AuSn solder.
  • 13. The laser diode assembly as claimed in claim 7, wherein the solder comprises a high temperature solder.
  • 14. The laser diode assembly as claimed in claim 13, wherein the solder comprises an AuGe solder or an AuSn solder.
  • 15. A method of forming a laser diode array as claimed in claim 1, comprising: providing a heat sink bonded to an insulating layer;forming grooves in the insulating layer; andbonding laser diode bars aligned over the grooves.
  • 16. The method as claimed in claim 15, wherein the grooves are formed into the heat sink.
  • 17. The method as claimed in claim 15, wherein the grooves are formed parallel to one another.
  • 18. The method as claimed in claim 15, wherein the laser diode bars are bonded over the grooves by soldering.
  • 19. The method as claimed in claim 18, wherein a hard solder is used in the soldering.
  • 20. The method as claimed in claim 19, wherein the hard solder comprises an AuGe solder or an AuSn solder.
CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional Application Ser. No. 60/822,071, filed Aug. 10, 2006 the contents of which are incorporated herein by reference.

Provisional Applications (1)
Number Date Country
60822071 Aug 2006 US