LED lamp configured to minimize image contrast

• US 6,939,188 B2
• Filed: 07/29/2002
• Issued: 09/06/2005
• Est. Priority Date: 08/01/2001
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Katayama, Hiroyuki, Murata, Kazuhisa, Katoh, Masaaki
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): KEANEY, ELIZABETH MARIE
• Application Number:
  US10/208,382
• Publication Number:
  US 20030025450A1
• Time in Patent Office: 1,135 Days
• Field of Search: 445/58, 445/14, 445/13, 445/24, 257/680, 257/98, 257/99, 257/100, 438/22, 438/25, 438/26, 362/800, 313/512, 313/483, 313/502, 313/503, 313/113
• US Class Current: 445/13
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 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 2924/181 Encapsulation
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

An LED lamps capable of composing a display panel that is installed at any outdoor place and capable of displaying an image thereon with a high contrast under any working conditions at any place. The LED lamp comprises at least one LED chip for emitting visible light, a lead frame comprising a common part and separate parts for supplying electric power to each of electrode terminals of the LED chip and a transparent resin part disposed on the common lead frame for mounting the LED chip and converging light emitted from the LED chip, wherein the LED-chip-mounted surface is provided with an anti-reflection black-colored layer for absorbing light. The LED chip may be a four-element LED chip composed of an active layer of AlGaInP and the light-absorbing layer formed from any of black silver sulfide, silver oxide, iron oxide, chromium oxide, black silver paste and black copper paste.

Claims

1. A method of forming a light absorbing layer on an LED-chip-mounted surface of an LED, wherein the LED comprises an LED chip, a lead frame comprising a silver-plated common part and separate parts for supplying electric power to each electrode terminal of the LED chip, and a transparent resin part disposed on the lead frame for mounting the LED chip and converting light emitted from the LED chip, said method comprising:

sulfurizing the silver-plated surface with hydrogen sulfide solution or hydrogen sulfide gas after connecting the electrode terminals of the LED chip to said silver-plated common part by die-bonding using silver paste and said separate parts by wire-bonding.

2. A method of forming a light absorbing layer on an LED-chip-mounted surface of an LED, wherein the LED comprises an LED chip, a lead frame comprising a silver-plated common part and separate parts for supplying electric power to each electrode terminal of the LED chip, and a transparent resin part disposed on the lead frame for mounting the LED chip and converting light emitted from the LED chip, said method comprising:

oxidizing the silver-plated surface by immersing into nitric acid solution or exposing to ultraviolet rays in oxygen gas atmosphere after connecting the electrode terminals of the LED chip to said silver-plated common part by die-bonding using silver paste and said separate parts by wire-bonding.