Optocoupler with light guide defining element

• US 8,571,360 B2
• Filed: 11/12/2010
• Issued: 10/29/2013
• Est. Priority Date: 03/23/2010
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Tay, Thiam Siew Gary, Maasi, Gopinath
• Primary Examiner(s): Petkovsek, Daniel
• Application Number:
  US12/945,474
• Publication Number:
  US 20110235975A1
• Time in Patent Office: 1,082 Days
• Field of Search: 385/14, 385/39, 385 88- 94
• US Class Current: 385/14
• CPC Class Codes: G02B 6/4246 Bidirectionally operating package structures
• CPC Class Codes: H01L 31/167 the light sources and the devices sensitive to radiation all being semiconductor devices characterised by potential barriers

Abstract

An optocoupler with a light guide defining element is presented. The light guide defining element has at least one cavity configured to define the shape of the light guide formed by a transparent encapsulant encapsulating the optical transmitter and receiver dies. The transparent encapsulant in liquid form may be injected into the cavity prior to a curing process to harden the encapsulant into a light guide with a predetermined shape. The cavity of the light guide element may be defined by a reflective surface having micro-optics formed thereon. A multichannel optocoupler with multiple transmitter and/or receiver dies having such light guide defining element is also presented. The light guide defining element may have a single cavity enveloping all the optical transmitter or receiver dies, or a multiple cavities by having a pair of transmitter and receiver dies inside each cavity.

Claims

1. A packaging for an optocoupler, comprising:

a first optical transmitter die configured to emit light;

a first optical receiver die, the first optical receiver die configured to receive light emitted by the first optical transmitter die;

a plurality of conductors, the first optical transmitter die and the first optical receiver die being attached to at least one of the plurality of conductors;

a light guide, the light guide being a substantially transparent encapsulant encapsulating the first optical transmitter die and the first optical receiver die, the light guide configured to transfer light from the first optical transmitter die to the first optical receiver die;

an attachment member;

a light guide defining element attached to at least one of the plurality of conductors through the attachment member, the light guide defining element and the attachment member providing at least one cavity configured to bound the substantially transparent encapsulant, so as to define the shape of the transparent encapsulant of the light guide defining element as the transparent encapsulant is hardened from liquid form; and

an opaque encapsulant encapsulating the light guide defining element and partially encapsulating the plurality of conductors,

wherein the light guide defining element is formed from one of;

polycarbonate, high index plastic and acrylic plastic materials.

2. The packaging of claim 1, wherein one of the plurality of conductors defines a conductive pad, and wherein one of the first optical transmitter die and the first optical receiver die is attached directly to the conductive pad, the other one of the first optical transmitter die and the first optical receiver die is attached to the conductive pad via three layers of materials comprising an isolation layer sandwiched between two securing layers.

3. The packaging of claim 1, further comprising a tape, wherein the substantially transparent encapsulant is bounded by the light guide defining element and the tape.

4. The packaging of claim 1, wherein the attachment member is a non-conductive epoxy material.

5. The packaging of claim 1, further comprising a second optical transmitter die and a second optical receiver die.

6. The packaging of claim 5, wherein the first optical transmitter die and the first optical receiver die are encapsulated by the substantially transparent encapsulant within the cavity of the light guide defining element.

7. The packaging of claim 5, wherein the light guide defining element comprises a second cavity, such that the first optical transmitter die and the second optical receiver die are located in vicinity of one of the two cavities, and the second optical transmitter die and the second optical receiver die are located in the vicinity of another of the two cavities.

8. The packaging of claim 7, wherein the two cavities are optically separated through an optical separation element.

9. The packaging of claim 1, wherein the packaging forms a portion of an optocoupler.

10. The packaging of claim 1, wherein the light guide defining element comprises an aperture configured to prevent air from being trapped inside the at least one cavity.

11. An optocoupler comprising:

a plurality of conductive leads;

a first optical transmitter die configured to emit light, the first optical transmitter die configured to receive power through one of the plurality of conductive leads;

a first optical receiver die configured to receive light emitted by the first optical transmitter die, the first optical receiver die configured to be powered to receive power through one of the plurality of conductive leads;

a substantially transparent encapsulant at least partially encapsulating at least a portion of the plurality of conductive leads, the first optical transmitter die and the first optical receiver die, the substantially transparent encapsulant configured to form a light guide to transfer light from the first optical transmitter die to the first optical receiver die;

a light guide defining element, the light guide defining element having at least one cavity configured to bound the substantially transparent encapsulant, so as to define the shape of the substantially transparent encapsulant as the substantially transparent encapsulant is hardened from liquid form; and

an opaque encapsulant encapsulating the light guide defining element and a substantial portion of the plurality of conductive leads;

wherein the light guide defining element is formed from one of;

polycarbonate, high index plastic and acrylic plastic materials.

12. The optocoupler of claim 11, wherein one of the plurality of conductive leads defines a conductive pad, and wherein one of the first optical transmitter die and the first optical receiver die is attached directly to the conductive pad, the other one of the first optical transmitter die and the first optical receiver die is attached to the conductive pad via three layers of materials comprising an isolation layer sandwiched between two securing layers.

13. The optocoupler of claim 11, wherein the light guide defining element is attached to a portion of the plurality of conductive leads using an attachment member.

14. The optocoupler of claim 13, wherein the attachment member is a non-conductive epoxy.

15. The optocoupler of claim 11, further comprising a second optical transmitter die and a second optical receiver die, wherein the second optical transmitter die and the second optical receiver die are encapsulated by the substantially transparent encapsulant within the at least one cavity of the light guide defining element.

16. The optocoupler of claim 11, wherein the light guide defining element comprises a second cavity, and wherein the optocoupler further comprises a second optical transmitter die and a second optical receiver die, wherein the first optical transmitter die and the first optical receiver die are located in the vicinity of either the at least one cavity or the second cavity, and the second optical transmitter die and the optical receiver die are located in vicinity of the another of the at least one cavity or the second cavities.

17. The optocoupler of claim 16, wherein the at least one cavity and the second cavity are optically separated through an optical separation means.

18. The optocoupler of claim 11, wherein the light guide defining element comprises an aperture configured to prevent air from being trapped inside the at least one cavity.

19. An optocoupler comprising:

a substrate;

a first optical transmitter die located on the substrate configured to emit light, the first optical transmitter die configured to receive a first power;

a first optical receiver die located on the substrate, the first optical receiver die configured to receive light emitted by the first optical transmitter die and configured to receive a second power;

a substantially transparent encapsulant encapsulating a portion of the substrate, the first optical transmitter die and the first optical receiver die, wherein the substantially transparent encapsulant is hardened from liquid form to fowl a light guide configured to transfer light from the first optical transmitter die to the first optical receiver die;

a light guide defining element attached to the substrate, the light guide defining element having a cavity configured to bound the substantially transparent encapsulant when the transparent encapsulant is in liquid form and define therein at least a portion of the shape of the substantially transparent encapsulant to form the light guide;

an aperture on the light guide defining element configured to prevent air from being trapped inside the cavity; and

an opaque encapsulant encapsulating the light guide defining element and a substantial portion of the substrate.