Packaging of light-emitting diode

• US 6,531,328 B1
• Filed: 10/11/2001
• Issued: 03/11/2003
• Est. Priority Date: 10/11/2001
• Status: Active Grant

• Current Assignee: Solidlite Corp.
• Original Assignee: Solidlite Corp.
• Inventors: Chen, Hsing
• Primary Examiner(s): Zarabian, Amir
• Assistant Examiner(s): NOVACEK, CHRISTY L
• Application Number:
  US09/973,777
• Time in Patent Office: 516 Days
• Field of Search: 438/106, 438/26, 438/28, 438/43, 438/25
• US Class Current: 438/26
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• 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 2224/81 using a bump connector
• CPC Class Codes: H01L 2224/85 using a wire connector
• 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 24/97 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 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 2924/00014 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 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01006 Carbon [C]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/01047 Silver [Ag]
• CPC Class Codes: H01L 2924/0106 Neodymium [Nd]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/01082 Lead [Pb]
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/10329 Gallium arsenide [GaAs]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2933/0033 : relating to semiconductor body packages
• CPC Class Codes: H01L 33/486 : adapted for surface mounting
• CPC Class Codes: H01L 33/60 : Reflective elements
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H01L 33/641 : characterized by the materials

Abstract

The present invention of “Packaging of Light-Emitting Diode” is mainly to use silicon wafer as the substrate, whose crystal surface has a specific orientation for etching to form grooves. On the back of silicon substrate, dry etching is used for through-hole electrodes. Meanwhile, the insulating oxide layer or the nitride layer on silicon surface is plated with a reflective layer and an electrode layer, so the LED substrate is actually made of “silicon substrate”. Through the procedures including placement of LED chips in the grooves of a silicon substrate, die bonding, wire bonding, encapsulation and cutting, SMD LED can be formed. Compared to traditional LED packaging that uses circuit boards or metal leadframes as main packaging substrates, the present invention is a breakthrough, which uses silicon wafers as substrates, so it has several advantages including good heat dissipation, high heat resistance and easy miniaturization, which are not seen in common LED presently.

Claims

1. A process for forming an LED packaging substrate, comprising the steps of:

a. providing a silicon wafer substrate having opposing front and back sides;

b. applying photoresist on the front side of the silicon wafer substrate;

c. exposing and developing the photoresist to define predetermined areas;

d. wet etching the substrate to form groove reflectors;

e. applying photoresist on the back side of the silicon wafer substrate;

f. exposing and developing the photoresist to define a through-hole pattern in respective aligned relationship with the groove reflectors;

g. dry etching the through-hole pattern to form electrode holes through the silicon wafer substrate;

h. removing the photoresist from the silicon wafer substrate;

i. forming an insulation layer on the front and back sides of the substrate by oxidation or nitridation;

j. applying a conductive metal layer by electroplating to the front and back sides of silicon substrate and inside electrode holes; and

,

k. laser treating the conductive metal layer to cut an electrode surface in the groove reflectors into positive and negative electrode contacting surfaces for respective connection with LED chips placed inside the groove reflectors.

2. The process for forming an LED packaging substrate of claim 1, wherein the conductive metal plating layer provides both electrical conductance and light reflection and is made of materials selected from the group consisting of Ag, Au, Pd, and Pt.

3. The process for forming an LED packaging substrate of claim 1, wherein the silicon wafer substrate uses (100) crystallization orientation to form the groove reflectors with declining walls by etching in step d.

4. The process for forming an LED packaging substrate of claim 1, wherein the silicon wafer substrate uses (110) crystallization orientation to form the groove reflectors with vertical walls by etching in step d.

5. The process for forming an LED packaging substrate of claim 1, wherein the wet etching step includes the step of using an etching solution of KOH.

6. A process for forming an LED packaging substrate of claim 1, further comprising the steps of:

placing LED chips in the groove reflectors of the silicon wafer substrate;

respectively connecting positive and negative electrodes of the LED chips to the positive and negative electrode contacting surfaces of the groove reflectors of the silicon wafer substrate;

covering the LED chips and completely filling the groove reflectors with an encapsulating resin;

heating the silicon wafer substrate to cure the encapsulating resin; and

,

cutting the silicon wafer substrate to form individual SMD LED dies.

7. The process for forming an LED packaging substrate of claim 6, wherein the encapsulating resin is a transparent and high-temperature resistant silicon rubber or epoxy.