Method of making a semiconductor radiation emitter package

• US 20020004251A1
• Filed: 08/23/2001
• Published: 01/10/2002
• Est. Priority Date: 03/15/1999
• Status: Active Grant

• Current Assignee: John K. Roberts, Joseph S. Stam, Robert R. Turnbull, Spencer D. Reese
• Original Assignee: John K. Roberts, Joseph S. Stam, Robert R. Turnbull, Spencer D. Reese
• Inventors: Roberts, John K., Turnbull, Robert R., Stam, Joseph S., Reese, Spencer D.
• Granted Patent: US 6,828,170 B2
• Time in Patent Office: Days
• US Class Current: 438/26
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/05624 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05639 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/05644 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05647 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2224/48624 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48639 Silver (Ag) as principal constituent
• CPC Class Codes: H01L 2224/48644 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48647 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48724 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/48739 Silver (Ag) as principal constituent
• CPC Class Codes: H01L 2224/48744 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48747 : Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/49171 : Fan-out arrangements
• CPC Class Codes: H01L 2224/73265 : Layer and wire connectors
• CPC Class Codes: H01L 23/49562 : for devices being provided for in H01L29/00
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/45 : of an individual wire connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/49 : of a plurality of wire connectors
• CPC Class Codes: H01L 24/73 : Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01004 : Beryllium [Be]
• CPC Class Codes: H01L 2924/01005 : Boron [B]
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01013 : Aluminum [Al]
• CPC Class Codes: H01L 2924/01014 : Silicon [Si]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/0102 : Calcium [Ca]
• CPC Class Codes: H01L 2924/01023 : Vanadium [V]
• CPC Class Codes: H01L 2924/01027 : Cobalt [Co]
• CPC Class Codes: H01L 2924/01028 : Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 : Copper [Cu]
• CPC Class Codes: H01L 2924/0103 : Zinc [Zn]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01041 : Niobium [Nb]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/01068 : Erbium [Er]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01075 : Rhenium [Re]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/01088 : Radium [Ra]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/10329 : Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/10336 : Aluminium gallium arsenide [AlGaAs]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/12044 : OLED
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/351 : Thermal stress
• CPC Class Codes: H01L 2933/0091 : Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/642 : characterized by the shape
• CPC Class Codes: H01L 33/647 : the elements conducting electric current to or from the semiconductor body
• CPC Class Codes: H10K 50/84 : Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/85 : Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/87 : Arrangements for heating or cooling

Abstract

A semiconductor optical radiation package includes a leadframe, at least one semiconductor optical radiation emitter, and an encapsulant. The leadframe has a heat extraction member, which supports the semiconductor optical emitter and provides one or more thermal paths for removing heat generated within the emitter to the ambient environment, as well as at least two electrical leads for providing electrical coupling to the semiconductor optical radiation emitter. The encapsulant covers and protects the emitter and optional wire bonds from damage and allows radiation to be emitted from the emitter into the ambient environment. The semiconductor optical radiation package provides high emitted flux and is preferably compatible with automated processing techniques.

Claims

1. A method of making a semiconductor radiation emitter package comprising:

forming a leadframe assembly from a sheet of electrically and thermally conductive material, the leadframe assembly having a heat extraction element and a plurality of thermally resistive leads, at least one tie-bar connecting at least one lead to another lead;

bonding at least one semiconductor radiation emitter to the heat extraction element, each emitter having a plurality of electrical connection points;

forming an electrical connection between at least one electrical connection point and at least one lead connected to the other lead by the at least one tie-bar;

encapsulating the at least one semiconductor radiation emitter with a material substantially transparent to wavelengths emitted by the at least one semiconductor radiation emitter; and

breaking each of the at least one tie-bar.

2. A method of making a plurality of semiconductor radiation emitter packages comprising the steps of:

forming a leadframe assembly from a sheet of electrically and thermally conductive material, the leadframe assembly having a plurality of leadframes each including a heat extraction element and a plurality of thermally resistive leads, the leadframe assembly further including a plurality of tie-bars connecting said plurality of leadframes to one another;

bonding at least one semiconductor radiation emitter to each heat extraction element, each emitter having a plurality of electrical connection points;

forming an electrical connection between at least one electrical connection point of said at least one said semiconductor radiation emitter and at least one of said plurality of leads of a corresponding one of said leadframes; and

encapsulating said at least one semiconductor radiation emitter with a material substantially transparent to wavelengths emitted by the at least one semiconductor radiation emitter so as to create a plurality of interconnected semiconductor radiation emitter packages.

3. The method of claim 2 and further comprising the step of breaking each of the tie-bars to separate the semiconductor radiation emitter packages from one another.

4. The method of claim 2, wherein the leadframe assembly includes an additional tie-bar for each leadframe that couples together at least two of said electrical leads.

5. The method of claim 2, wherein the leadframe assembly includes an additional tie-bar for each leadframe that couples at least one of said electrical leads to one of said heat extraction members.

6. The method of claim 2, wherein said tie-bars couple together at least two of said heat extraction members.

7. The method of claim 2 and further comprising the step of forming at least one recessed cup in each heat extraction member and attaching the at least one semiconductor radiation emitter in said recessed cup.

8. The method of claim 7 and further comprising the step of coating each recessed cup with an optically reflective coating.

9. The method of claim 2, wherein said plurality of electrical leads for each leadframe includes first and second electrical leads, said second electrical lead is formed as an integral extension of the heat extraction member.

10. The method of claim 2, wherein said plurality of electrical leads is formed thinner than the heat extraction members.

11. The method of claim 2, wherein the thickness of the heat extraction members are formed to be at least three times the thickness of each electrical lead.

12. The method of claim 2, wherein at least one of said plurality of electrical leads for each leadframe is electrically isolated from the heat extraction member.

13. The method of claim 12 and further including the step of providing a tie-bar for each leadframe to connect each isolated electrical lead to one of the heat extraction member and another of the plurality of leads.

14. The method of claim 13, wherein said step of encapsulating includes covering a portion of each isolated lead with material.

15. The method of claim 14 and further including the step of breaking the tie-bar connecting each isolated electrical lead to one of the heat extraction member and another of the plurality of leads after the encapsulating step.

16. The method of claim 2, wherein said step of forming a leadframe assembly includes stamping the assembly out of an integral metal strip.

17. The method of claim 2, wherein each of the heat extraction members is constructed with a thick cross-sectional area normal to the path of heat flow away from the at least one semiconductor radiation emitter relative to the thickness of the electrical leads.

18. The method of claim 2, wherein each of the heat extraction members is formed with at least one of notches, fins, slots, and holes to increase surface area outside a portion of the heat extraction members to be covered with an encapsulant.

19. The method of claim 2, wherein each of the heat extraction members is formed in the shape of a plate.