News Column

Patent Issued for Light Emitting Diode Package Structure and Manufacturing Method

August 20, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventor Lin, Hsien Chia (New Taipei, TW), filed on June 29, 2011, was published online on August 5, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8796713 is assigned to Everlight Electronics Co., Ltd. (TW).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present disclosure relates to a semiconductor package structure and a manufacturing method thereof. More particularly, the present disclosure relates to a light emitting diode (LED) package structure and a manufacturing method thereof.

"LEDs generally offer a number of advantageous characteristics such as long product life, compact size, high shock resistance, low heat generation and low power consumption, etc. As a result LEDs are widely employed in household applications and as the light source or indicator of a variety of equipment. Recent developments of new LEDs are in the areas of multiple colors and high brightness. Accordingly, LEDs are further employed in applications such as large outdoor bulletin boards, traffic signals and related fields. In the future, LEDs may even become the primary light source for illumination that not only conserve electricity but also are environmentally friendly.

"Among the white-light LED package structures commonly adopted in the market, a type of white-light LED is composed of a blue-light LED chip and yellow phosphor. A prior art manufacturing method of a white-light LED package structure typically disposes a blue-light LED chip on a base and wire bonds the blue-light LED chip with the base. Afterwards, using spin coating, dispensing, spray coating, molding or any other suitable process on the base, a yellow fluorescent layer is formed on the blue-light LED chip. A portion of the yellow fluorescent layer emits yellow light upon excitation by the blue light emitted by the blue-light LED chip, and in turn the yellow light, combined with the blue light emitted by the blue-light LED chip, produces white light. However, a yellow fluorescent layer formed by spin coating, dispensing, spray coating or the like tends to suffer from excessive usage of phosphor powder and results in uneven thickness of the layer. That is, when the blue light emitted by the blue-light LED chip traverses through a yellow fluorescent layer of a greater thickness, the white-light LED package structure may produce a yellowish halo, causing the color of the light emitted by the LED package structure to be uneven overall.

"In order to address the problem associated with uneven spin-coating of the fluorescent layer, U.S. Pat. No. 6,395,564 and U.S. Patent Publication No. 2009/0261358 disclose a technique that involves spraying the fluorescent layer directly on wafers and forming white-light LED package structures after cutting the wafers. However, such prior art technique suffers from the problem of lowered scattering efficiency during the process of the yellow fluorescent layer emitting yellow light upon excitation by the blue light. Additionally, as difference in wavelengths may result from crystalline growth on wafers, manufacturing costs tend to increase if the difference in wavelengths is to be rectified by way of spin-coating fluorescent layer on wafers.

"In order to address the problem associated with low scattering efficiency, U.S. Pat. No. 6,630,691 discloses a manufacturing method of a phosphor layer. Ceramic glass and phosphor are combined under high temperature to result in a eutectic process that forms a fluorescent substrate, which is pasted to LED chips to avoid the issue of low scattering efficiency and enhance the uniformity of light generated by the LED package structure. However, as such prior art technique provides no electrode design for the fluorescent substrate, the use of this technique is limited to flip chip LED chips."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "The present disclosure provides an LED package structure and a manufacturing method thereof that can help enhance the uniformity in the color of light generated by LED chips.

"In one aspect, an LED package structure may comprise a substrate, first and second electrically conductive patterns, at least one electrically conductive component, and an LED chip. The substrate may have a first surface and a second surface opposite to the first surface. The first electrically conductive pattern may be disposed on the first surface of the substrate. The second electrically conductive pattern may be disposed on the second surface of the substrate. The at least one electrically conductive component may traverse the substrate and connect the first electrically conductive pattern and the second electrically conductive pattern. The LED chip may be disposed on the second surface of the substrate. The LED chip may have a light extraction surface coupled to the second electrically conductive pattern such that the LED chip is electrically coupled to the first electrically conductive pattern via the at least one electrically conductive component.

"The substrate may be a fluorescent substrate comprising a mixture of at least one fluorescent material and a transparent material. In one embodiment, the at least one fluorescent material may comprise a yellow phosphor. In another embodiment, the at least one fluorescent material may comprise phosphors of at least two different wavelengths. The phosphors may comprise at least two of yellow phosphor, red phosphor, and green phosphor.

"In one embodiment, the LED package structure may further comprise an underfill disposed between the light extraction surface of the LED chip and the second surface of the fluorescent substrate. The underfill may cover at least partially the light extraction surface of the LED chip. Additionally or alternatively, the underfill may cover at least partially a side surface of the LED chip.

"In one embodiment, the LED chip may comprise a sapphire substrate. Alternatively, the LED chip may comprise a blue-light LED chip.

"In one embodiment, the LED package structure may further comprise a circuit board where a back surface of the LED chip opposite to the light extraction surface may be disposed on the circuit board. Additionally, at least one bonding wire may electrically couple the circuit board and the first electrically conductive pattern.

"In another aspect, a manufacturing method of an LED package structure may comprise: providing a substrate having a first surface and a second surface opposite to the first surface, the substrate containing therein at least one electrically conductive component that connects the first surface and the second surface; forming a first electrically conductive pattern on the first surface and a second electrically conductive pattern on the second surface such that the at least one electrically conductive component electrically couples the first electrically conductive pattern and the second electrically conductive pattern; and bonding an LED chip on the second surface of the fluorescent substrate with a light extraction surface of the LED chip coupled to the second electrically conductive pattern, the LED chip electrically coupled to the first electrically conductive pattern via the at least one electrically conductive component.

"In one embodiment, providing the substrate may comprise providing a fluorescent substrate that comprises a mixture of at least one fluorescent material and a transparent material. The at least one fluorescent material may comprise a yellow phosphor, phosphors of at least two different wavelengths, or at least two of yellow phosphor, red phosphor, and green phosphor.

"In one embodiment, the method may further comprise: forming at least one through hole in the substrate, the at least one through hole connecting the first surface and the second surface of the substrate; electroplating the at least one through hole to form at least one respective electrically conductive pillar protruding out of the first surface of the substrate; and polishing the at least one electrically conductive pillar to provide the at least one electrically conductive component that is flush with the first surface of the substrate. The polishing may comprise cutting the substrate with a cutting device to reduce a thickness of the substrate and to expose the at least one electrically conductive component.

"In another embodiment, the method may further comprise: providing at least one electrically conductive bump in a recess of a supporting substrate; filling the recess of the supporting substrate with the at least one fluorescent material and the transparent material, the at least one fluorescent material and the glass material covering the at least one electrically conductive bump; heating the at least one electrically conductive bump, the at least one fluorescent material, and the glass material together to form the fluorescent substrate with the at least one electrically conductive bumps embedded therein; and polishing the fluorescent substrate and the at least one electrically conductive bump to form the at least one electrically conductive component that is flush with the first surface of the fluorescent substrate.

"In yet another embodiment, the method may further comprise forming at least one conductive line on the second surface after forming the second electrically conductive pattern, the at least one conductive line connecting the second electrically conductive pattern.

"In still another embodiment, the method may further comprise forming an underfill between the light extraction surface of the LED chip and the second surface of the substrate after bonding the LED chip on the second surface of the substrate, the underfill covering at least partially the light extraction surface of the LED chip. The underfill may cover at least partially a side surface of the LED chip.

"In a further aspect, an LED package structure may comprise a substrate, a first electrically conductive pattern, a second electrically conductive pattern, at least one electrically conductive component, and a blue LED chip. The substrate may have a first surface and a second surface opposite to the first surface. The substrate may comprise a yellow phosphor and a transparent material. The first electrically conductive pattern may be disposed on the first surface of the substrate. The second electrically conductive pattern may be disposed on the second surface of the substrate. The at least one electrically conductive component may penetrate the substrate. The at least one electrically conductive component may connect the first electrically conductive pattern and the second electrically conductive pattern. The blue LED chip may be disposed on the second surface of the substrate. The blue LED chip may have a light extraction surface coupled to the second electrically conductive pattern such that the blue LED chip is electrically coupled to the first electrically conductive pattern via the at least one electrically conductive component.

"These and other features, aspects, and advantages of the present disclosure will be explained below with reference to the following figures. It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the present disclosure as claimed."

URL and more information on this patent, see: Lin, Hsien Chia. Light Emitting Diode Package Structure and Manufacturing Method. U.S. Patent Number 8796713, filed June 29, 2011, and published online on August 5, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8796713.PN.&OS=PN/8796713RS=PN/8796713

Keywords for this news article include: Circuit Board, Light-emitting Diode, Everlight Electronics Co. Ltd..

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Source: Electronics Newsweekly


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