Methods of forming packaged semiconductor light emitting devices having front contacts by compression molding

• US 9,061,450 B2
• Filed: 02/12/2007
• Issued: 06/23/2015
• Est. Priority Date: 02/12/2007
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Medendorp, Nicholas W. Jr.
• Primary Examiner(s): FERNANDES, ERROL V
• Application Number:
  US11/705,233
• Publication Number:
  US 20080191225A1
• Time in Patent Office: 3,053 Days
• Field of Search: 257/98, 257/95, 257/89, 257/79, 257/77, 257/76, 257/676, 257/433, 257/103, 257/100, 257/82, 438/107, 438/22, 438/27, 438/33, 438/39, 438/45, 438/29, 438/26
• US Class Current: 1/1
• CPC Class Codes: B29C 33/0022 Multi-cavity moulds B29C33/301 takes precedence
• CPC Class Codes: B29C 33/02 with incorporated heating or cooling means
• CPC Class Codes: B29C 43/021 characterised by the shape of the surface
• CPC Class Codes: B29C 43/18 incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles B29C43/206 takes precedence
• CPC Class Codes: B29L 2011/0016 Lenses
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• 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 2924/00014 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 2924/01068 Erbium [Er]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 33/52 Encapsulations

Abstract

Methods of packaging a semiconductor light emitting device include providing a substrate having the semiconductor light emitting device on a front face thereof and a contact on a front face thereof, wherein the light emitting device is electrically connected to the contact on the front face of the substrate. The substrate is compression molded to form an optical element on the front face of the substrate over the semiconductor light emitting device and a residual coating over a region of the front face of the substrate including the contact. The residual coating over the contact may be removed without damaging the contact. Packaged semiconductor light emitting devices are also provided.

Claims

1. A method of packaging a semiconductor light emitting device, comprising:

providing a substrate having the semiconductor light emitting device on a front face thereof and a contact on the front face thereof, wherein the light emitting device is electrically connected to the contact on the front face of the substrate;

providing a mask covering a first portion of the contact, wherein a second portion of the contact is free of the mask;

compression molding an optical element on the front face of the substrate over the semiconductor light emitting device and a residual coating over a region of the front face of the substrate including the contact, including applying heat to cure the optical element and residual coating; and

removing the residual coating and the mask from the first portion of the contact without damaging the contact to form a compression molded lens that covers the semiconductor light emitting device and the second portion of the contact.

2. The method of claim 1, wherein providing a substrate comprises:

mounting the semiconductor light emitting device on the front face of the substrate; and

attaching a wire bond electrically connecting the semiconductor light emitting device to a contact portion of the substrate.

3. The method of claim 2, further comprising mounting a second semiconductor light emitting device on a back face of the substrate and electrically connecting the second semiconductor light emitting device to a contact on the back face of the substrate.

4. The method of claim 2, wherein compression molding comprises compression molding the substrate to form the optical element over the semiconductor light emitting device and the wire bond and directly contacting the wire bond.

5. The method of claim 1, wherein the substrate comprises a ceramic substrate, a metal core printed circuit board (MCPCB), a flexible circuit substrate and/or a lead frame.

6. The method of claim 1, wherein the mask comprises a polyimide film.

7. The method of claim 1, wherein removing the mask comprises:

cutting the residual coating in a pattern corresponding to the mask; and

removing the mask and the overlying residual coating thereon to expose the front side contact.

8. The method of claim 1, wherein the substrate comprises a flexible circuit substrate and wherein removing the residual coating comprises wet solvent chemical cleaning the substrate to remove the residual coating over the contact.

9. The method of claim 8, wherein the substrate includes a plurality of semiconductor light emitting devices and contacts on the front face thereof and wherein compression molding the substrate comprises compression molding the substrate to form a plurality of optical elements on the front face of the substrate over corresponding ones of the semiconductor light emitting devices and a residual coating over a region of the front face of the substrate including the plurality of contacts.

10. The method of claim 9, wherein the optical elements comprise lenses and wherein compression molding comprises:

placing the substrate in a mold including a plurality of lens shaped cavities positioned proximate corresponding ones of the plurality of semiconductor light emitting devices;

providing silicone into the mold;

compression molding the lenses from the silicone in the cavities; and

removing the substrate with the lenses formed therein from the mold.

11. The method of claim 1, wherein the optical element comprises a first and a second optical element and wherein compression molding comprises:

compression molding the first optical element proximate the semiconductor light emitting device; and

compression molding the second optical element over the semiconductor light emitting device and the first optical element.

12. The method of claim 11, wherein compression molding the first optical element comprises compression molding the first optical element over the semiconductor light emitting device.

13. The method of claim 1, wherein the optical element comprises a second optical element and wherein compression molding is preceded by forming a first optical element proximate the semiconductor light emitting device and wherein compression molding the substrate comprises compression molding the second optical element over the semiconductor light emitting device and the first optical element.

14. The method of claim 1, wherein the optical element comprises a first optical element and wherein compression molding is followed by forming a second optical element over the semiconductor light emitting device and the first optical element.

15. The method of claim 1, wherein compression molding comprises applying the heat of at least 100°

C. for a time of at least 3 minutes at a pressure of at least 0.1 tons/in².

16. The method of claim 1, wherein the contact is adjacent the semiconductor light emitting device, the first portion of the contact is distal from the semiconductor light emitting device and the second portion of the contact is proximal to the semiconductor light emitting device.

17. The method of claim 1, wherein the semiconductor light emitting device comprises a first semiconductor light emitting device, wherein the substrate includes a second semiconductor light emitting device on the front face thereof, and wherein removing the residual coating comprises removing the residual coating from between the first semiconductor light emitting device and the second semiconductor light emitting device.

18. The method of claim 17, wherein the mask is on the substrate between the first and second semiconductor light emitting devices, and wherein removing the residual coating from between the first semiconductor light emitting device and the second semiconductor light emitting device comprises removing the mask from between the first semiconductor light emitting device and the second semiconductor light emitting device.

19. A method of packaging a plurality of semiconductor light emitting devices, comprising:

providing a substrate having the plurality of semiconductor light emitting devices and a plurality of contacts on a front face thereof, wherein the plurality of light emitting devices are electrically connected to the plurality of contacts on the front face of the substrate;

providing a mask covering the front side plurality of contacts;

compression molding a plurality of optical elements on the front face of the substrate over the plurality of semiconductor light emitting devices and a residual coating over a region of the front face of the substrate including the plurality of contacts, including applying heat to cure the plurality of optical elements and residual coating;

removing the residual coating over at least a portion of the plurality of contacts without damaging the plurality of contacts by cutting the residual coating in a pattern corresponding to the mask, wherein cutting the residual coating comprises cutting the residual coating with a hot knife, the hot knife having a two-dimensional pattern corresponding to the pattern cut in the residual coating and wherein cutting the residual coating comprises cutting the residual coating with a single direction motion of the hot knife into the residual coating; and

removing the mask and the overlying residual coating thereon to expose the plurality of front side contacts.

20. The method of claim 19, wherein the optical elements comprise lenses and wherein compression molding comprises:

placing the substrate in a mold including a plurality of lens shape cavities positioned proximate corresponding ones of the plurality of semiconductor light emitting devices;

providing silicone into the mold;

compression molding the lenses from the silicone in the cavities; and

removing the substrate with the lenses formed therein from the mold.

21. The method of claim 20, wherein providing silicone is preceded by providing a release layer on a surface of the mold including the cavities and wherein removing the substrate comprises removing the substrate at the release layer.

22. A method of packaging a semiconductor light emitting device, comprising:

providing a substrate having the semiconductor light emitting device on a front face thereof and a contact on the front face thereof, wherein the light emitting device is electrically connected to the contact on the front face of the substrate;

compression molding an optical element on the front face of the substrate over the semiconductor light emitting device and a residual coating over a region of the front face of the substrate including the contact, including applying heat to cure the optical element and residual coating; and

removing the residual coating over at least a portion of the contact without damaging the contact by cutting, with a single direction motion, into the residual coating with a hot knife having a two-dimensional pattern.