Thyristor and thermal switch device and assembly techniques therefor

• US 10,177,081 B2
• Filed: 01/13/2017
• Issued: 01/08/2019
• Est. Priority Date: 01/13/2017
• Status: Active Grant

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Littlefuse Incorporated
• Inventors: Yoshimoto, Koichiro
• Primary Examiner(s): Miller, Jami V
• Application Number:
  US15/406,065
• Publication Number:
  US 20180204789A1
• Time in Patent Office: 725 Days
• Field of Search: 257119, 257712, 337298, 337304
• CPC Class Codes: H01C 1/1406 Terminals or electrodes formed on resistive elements having positive temperature coefficient
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/97 the devices being connected to a common substrate, e.g. interposer, said common substrate being separable into individual assemblies after connecting
• CPC Class Codes: H01L 23/49562 for devices being provided for in H01L29/00
• CPC Class Codes: H01L 23/49568 specifically adapted to facilitate heat dissipation
• CPC Class Codes: H01L 23/49575 Assemblies of semiconductor devices on lead frames
• CPC Class Codes: H01L 23/49582 Metallic layers on lead frames
• CPC Class Codes: H01L 23/525 with adaptable interconnections
• CPC Class Codes: H01L 28/26 with an active material comprising an organic conducting material, e.g. conducting polymers
• CPC Class Codes: H01L 29/74 Thyristor-type devices, e.g. having four-zone regenerative action two-terminal thyristors H01L29/87
• CPC Class Codes: H01L 29/747 Bidirectional devices, e.g. triacs
• 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 2924/181 Encapsulation
• CPC Class Codes: H02H 9/026 Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient

Abstract

A device may include a lead frame, where the lead frame includes a central portion, and a side pad, the side pad being laterally disposed with respect to the central portion. The device may further include a thyristor device, the thyristor device comprising a semiconductor die and further comprising a gate, wherein the thyristor device is disposed on a first side of the lead frame on the central portion. The device may also include a positive temperature coefficient (PTC) device electrically coupled to the gate of the thyristor device, wherein the PTC device is disposed on the side pad on the first side of the lead frame; and a thermal coupler having a first end connected to the thyristor device and a second end attached to the PTC device.

Claims

1. A hybrid device, comprising:

a lead frame, the lead frame comprising;

a central portion; and

a side pad, the side pad being laterally disposed with respect to the central portion;

a thyristor device, the thyristor device comprising a semiconductor die and further comprising a gate, wherein the thyristor device is disposed on a first side of the lead frame on the central portion;

a positive temperature coefficient (PTC) device electrically coupled to the gate of the thyristor device, wherein the PTC device is disposed on the side pad on the first side of the lead frame, and is not disposed on the thyristor device; and

a thermal coupler having a first end connected to the thyristor device and a second end attached to the PTC device.

2. The hybrid device of claim 1 wherein the lead frame comprises a copper material.

3. The hybrid device of claim 1, wherein the thermal coupler comprises a copper arm, the copper arm electrically connecting the gate to the PTC device.

4. The hybrid device of claim 3, wherein the thyristor device comprises an upper surface, the upper surface including a gate electrode and a first main terminal electrode, wherein the first main terminal electrode surrounds the gate electrode and is electrically isolated from the gate electrode.

5. The hybrid device of claim 4, further comprising a main terminal contact clip, arranged to contact the first main terminal electrode while not contacting the copper arm.

6. The hybrid device of claim 4, the lead frame further comprising:

a first main terminal lead, electrically coupled to the first main terminal electrode of the thyristor device;

a second main terminal lead, electrically coupled to a second main terminal electrode of the thyristor device on a lower surface opposite the upper surface; and

a gate lead, electrically coupled to the PTC device.

7. The hybrid device of claim 6, wherein the copper arm connects to a first surface of the PTC device, and wherein the gate lead connects to a second surface of the PTC device, the second surface being opposite the first surface.

8. The hybrid device of claim 1, wherein the thyristor device comprises a TRIAC.

9. The hybrid device of claim 1, wherein the PTC device comprises a polymer PTC.

10. The hybrid device of claim 1, wherein the PTC device comprises a trip temperature, wherein the thyristor device comprises a maximum junction temperature, and wherein the maximum junction temperature exceeds the trip temperature by 20 degrees C. or less.

11. A method for forming a hybrid device, comprising:

providing a lead frame, the lead frame comprising;

a central portion; and

a side pad, the side pad being laterally disposed with respect to the central portion;

affixing a thyristor device to a first side of the central portion of the lead frame, the thyristor device comprising a semiconductor die and further comprising a gate;

affixing a positive temperature coefficient (PTC) device to the side pad on the first side of the lead frame, wherein the PTC device is not disposed on the thyristor device; and

connecting a first end of a thermal coupler to the thyristor device and a second end of the thermal coupler to the PTC device, wherein the gate of the thyristor device is electrically connected to the PTC device.

12. The method of claim 11, wherein the thermal coupler comprises a copper arm, the copper arm electrically connecting the gate to the PTC device.

13. The method of claim 12, further comprising:

providing a gate electrode and a first main terminal electrode on an upper surface of the thyristor device, wherein the first main terminal electrode surrounds the gate electrode and is electrically isolated from the gate electrode; and

affixing a main terminal contact clip to the first main terminal electrode while not contacting the copper arm or the gate electrode.

14. The method of claim 13, further comprising:

connecting a first main terminal lead to the main terminal contact clip;

coupling a second main terminal lead to a second main terminal contact of the thyristor device on a lower surface opposite the upper surface; and

connecting a gate lead to the PTC device.

15. The method of claim 14, wherein the connecting the second end of the thermal coupler to the PTC device comprises connecting the thermal coupler to a first surface of the PTC device, and wherein the connecting the gate lead to the PTC device comprises connecting the gate lead connects to a second surface of the PTC device, the second surface being opposite the first surface.

16. The method of claim 11, wherein the thyristor device comprises a TRIAC.

17. The method of claim 11, wherein the PTC device comprises a polymer PTC.