US 7,253,448 B2 · Semiconductor radiation emitter package

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.

Drawings

Drawings are temporarily unavailable. Open the PDF at USPTO

Drawings

Claims156

Dependent claims

A semiconductor radiation emitter package comprising:

a heat extraction element;
at least two electrical leads having a greater thermal resistance than said heat extraction element;
at least one semiconductor radiation emitter mounted on a first surface of said heat extraction element, wherein when said at least one semiconductor radiation emitter is activated, the semiconductor radiation emitter package emits white light;
and
an encapsulant covering said at least one semiconductor radiation emitter, at least a portion of said encapsulant being substantially transparent to wavelengths emitted by said at least one semiconductor radiation emitter, said encapsulant material covering a portion of the first surface of said heat extraction element, while leaving exposed at least a portion of a second surface of said heat extraction element that is opposite the first surface, the exposed portion of the second surface being directly opposite an area of the first surface where said at least one semiconductor radiation emitter is mounted.

2 more elements

A semiconductor radiation emitter package comprising:

a heat extraction element;
at least two electrical leads having a greater thermal resistance than said heat extraction element;
at least one semiconductor radiation emitter mounted on a first surface of said heat extraction element, wherein when said at least one semiconductor radiation emitter is activated, the semiconductor radiation emitter package emits white light;
and
a first hard molding compound and a second hard molding compound, said first hard molding compound is substantially transparent to radiation emitted by said at least one semiconductor radiation emitter and is provided within the optical path of radiation emitted from said at least one semiconductor radiation emitter, wherein said second hard molding compound covers a portion of the first surface of said heat extraction element, while leaving exposed at least a portion of a second surface of said heat extraction element that is opposite the first surface, the exposed portion of the second surface being directly opposite an area of the first surface where said at least one semiconductor radiation emitter is mounted.

2 more elements

A semiconductor radiation emitter package comprising:

a heat extraction element;
at least two electrical leads having a greater thermal resistance than said heat extraction element;
at least one semiconductor radiation emitter mounted on a first surface of said heat extraction element;
and
an encapsulant encapsulating said at least one semiconductor radiation emitter, a portion of said heat extraction element and a portion of said electrical leads, wherein a cross-sectional area of said heat extraction element measured in a plane normal to the path between said at least one semiconductor radiation emitter and the nearest unencapsulated surface of said heat extraction element is greater than a cross-sectional area of each of said electrical leads measured in a plane that is normal to the path of heat flow between said at least one semiconductor radiation emitter and the nearest unencapsulated surface of said electrical leads during operation of the package, wherein said encapsulant defines a plurality of sides and said heat extraction element extends out through two of said sides.

2 more elements

A semiconductor radiation emitter package comprising:

a heat extraction element;
at least two electrical leads having a greater thermal resistance than said heat extraction element;
at least one semiconductor radiation emitter mounted on a first surface of said heat extraction element, wherein when said at least one semiconductor emitter is activated, the semiconductor radiation emitter package emits white light;
a first hard molding compound substantially transparent to radiation emitted by said at least one semiconductor radiation emitter, said first hard molding compound is provided within the optical path of radiation emitted from said at least one semiconductor radiation emitter;
and
a second hard molding compound covering a portion of said heat extraction element, while leaving exposed a portion of said heat extraction element, said second hard molding compound being different from said first hard molding compound and encapsulating a portion of said electrical leads so as to retain said electrical leads.

3 more elements

An LED package comprising:

a heat extraction element having a first surface and a second surface that is opposite the first surface;
a first electrical lead and a second electrical lead, said electrical leads having a greater thermal resistance than said heat extraction element;
an LED chip mounted to the first surface of said heat extraction element for emitting light generally along an optical path, wherein said LED chip is energized via said first and second electrical leads, when said LED chip is energized, the LED package is capable of emitting white light;
and
an encapsulant covering a portion of said first and second electrical leads, said LED chip, and a portion of said heat extraction element, said encapsulant is formed to leave exposed at least a portion of the second surface of said heat extraction member, the exposed portion of said heat extraction member including a region generally directly opposite a location on the first surface where said LED chip is mounted,
wherein said encapsulant comprises two different materials including a first hard molding compound and a second hard molding compound, said first hard molding compound is substantially transparent to light emitted by said LED chip and is provided within the optical path of light emitted from said LED chip and is shaped to define a lens, wherein said second hard molding compound is provided where said encapsulant covers said electrical leads and in regions generally not within the optical path of light emitted from said LED chip, said second hard molding compound is substantially opaque,
wherein a cross-sectional area of said heat extraction element measured in a plane normal to the path between said LED chip and the nearest exposed surface of said heat extraction element is greater than a cross-sectional area of each of said electrical leads measured in a plane that is normal to the path of heat flow between said LED chip and the nearest exposed surface of said electrical leads, during operation of the package,
wherein said encapsulant forms a plurality of sides, said first and second electrical leads extend through one of a first set of encapsulant sides, said heat extraction member extends through at least one of a second set of encapsulant sides including at least two sides, the second set of encapsulant sides different from the first set of encapsulant sides, and
wherein said heat extraction element having a thickness in a direction that is substantially parallel to the direction in which light is emitted from the LED package that is greater than the thickness of said electrical leads.

6 more elements

Dependencies are inferred from the claim text.

Description19,039 words

Summary4,104 words

#The present invention relates to semiconductor radiation emitter packages such as, for example, light emitting diode (LED) packages.

#Semiconductor optical emitter components such as LED devices have become commonplace in a wide variety of consumer and industrial opto-electronic applications. Other types of semiconductor optical emitter components, including organic light emitting diodes (OLEDs), light emitting polymers (LEPs), and the like may also be packaged in discrete components suitable as substitutes for conventional inorganic LEDs in these applications.

#Visible LED components of all colors are used alone or in small clusters as status indicators on such products as computer monitors, coffee makers, stereo receivers, CD players, VCRs, and the like. Such indicators are also found in a diversity of systems such as instrument panels in aircraft, trains, ships, cars, trucks, minivans and sport utility vehicles, etc. Addressable arrays containing hundreds or thousands of visible LED components are found in moving-message displays, such as those found in many airports and stock market trading centers, and also as high brightness, large-area outdoor TV screens found in many sports complexes and on some urban billboards.

Brief description of the drawings24 figures

#In the drawings:

#FIG. 1 is a graph of current versus emitted flux for various theoretical package designs;

#FIG. 2 is a generalized schematic diagram of a semiconductor optical radiation emitter package;

Detailed description14,566 words

#Referring initially to FIG. 2, a semiconductor optical radiation device or package 200 according to the present invention contains three major components: a leadframe 201, at least one semiconductor optical radiation emitter 202, and an encapsulant 203. Each of these components shall now be described in detail.

#The leadframe 201 serves as a support for mounting a semiconductor optical radiation emitter 202, provides a mechanism for electrical connection to the semiconductor optical radiation emitter 202, and provides thermal paths for removing heat generated within the semiconductor optical radiation emitter 202 during operation and transferring this heat to adjacent media, adjacent structures, or the surrounding environment. The leadframe includes two primary elements: a heat extraction member 204 and a plurality of electrical leads, indicated collectively by 205.

#The heat extraction member 204 consists of a thermally conductive body, typically composed of metal but potentially composed of a thermally conductive ceramic or other material that provides a dominant path (distinct from the leads 205) to transfer heat generated by the emitter of the device into the ambient environment. Preferably, the heat extraction member 204 functions to transfer more of the heat generated by the emitter out of the device into the ambient environment than is transferred by the electrical leads 205. Most preferably, the heat extraction member 204 is constructed to transfer more than 75% to 90% of this heat out of the device into the ambient environment, adjacent structures, or surrounding media. In contrast to the complex subassembly of Johnson et al., which includes a TO-18 header component, a heat coupling means, and electrical pins that protrude through the header, no complicated header component is needed in the semiconductor optical radiation package 200 according to the present invention. Another distinguishing feature is that the heat extraction member 204 transfers heat out of the encapsulation 203 to the ambient environment via a path having a location separate from the points of entry into the encapsulation of the electrical leads 205. Thus, the heat extraction member 204 forms the dominant thermal conduit to and from the semiconductor optical emitter 202 within the device 200, a conduit that is substantially independent of the electrical conduits to and from the device.

Facts

Application

11/005,459Filed 6 Dec 2004 · continuation

Priority

15 Mar 1999

Published

US 2005/0077623 A114 Apr 2005

Granted

7 Aug 2007

Term ended

27 Nov 2019

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment, including 36 days of adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification23 codes

H10H 20/8582
Means for heat extraction or cooling: characterised by their shape
H10H 20/853
Encapsulations: characterised by their shape
H10H 20/857
Packages: interconnections, e.g. lead-frames, bond wires or solder balls
H10W 70/481
Leadframes: for devices being provided for in groups H10D8/00 - H10D48/00

Family

Application60/124,493Us provisional application · filed 15 Mar 1999

Application09/426,795Parent of this division · filed 22 Oct 1999

Application09/935,443Parent of this continuation · filed 23 Aug 2001

US 2005/0077623 A1Pre-grant publication · published 14 Apr 2005

US 6,828,170 B2Parent of this continuation

US 6,335,548 B1Parent of this division

Application09/935,443Parent of this division

US 2002/0004251 A1Published application

US 7,253,448 B2This patent

From the US filing history. Foreign family members aren’t listed.

Timeline

15 Mar 1999Priority claimedParent application 60/124,493
6 Dec 2004Application filedUS 11/005,459
14 Apr 2005PublishedUS 2005/0077623 A1
7 Aug 2007GrantedUS 7,253,448 B2
16 Jun 2017Assigned to Everlight Electronics Co., Ltdassignment of assignor's interest
26 Jul 2017Assigned to Everlight Electronics Co., Ltdassignment of assignor's interest
27 Nov 2019Term endedEstimated, includes 36 days of adjustment

Semiconductor radiation emitter package

Life of this patent

Semiconductor radiation emitter package

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims156

Description19,039 words

Drawings

Classification23 codes

Life of this patent

Description19,039 words