Embedded Overvoltage Protection for LED Substrates

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Solution Overview

Problem

Conventional overvoltage protection devices for LED products require significant space on the cooling substrate, limiting the positioning of LED chips, reducing light extraction and heat dissipation efficiency, and are difficult and expensive to manufacture due to high-temperature sintering processes.

Innovation Solution

An overvoltage protection device is fabricated by creating through holes in a substrate, filling them with a high thermal conductivity overvoltage protection material, and forming flat electrodes on the top and bottom walls using metallization techniques, allowing for a smooth substrate surface and free arrangement of LED chips while improving light extraction and heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional overvoltage protection devices (Zener diodes) are bonded to the cooling substrate using SMT or flip-chip technology, then overvoltage protection is achieved, but the substrate surface area is reduced and optical axis positioning is compromised

Engineering Contradiction:

Improveovervoltage protectionVSAvoidsubstrate surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The overvoltage protection device is embedded within the cooling substrate by forming through-holes and filling them with protective material, nesting the protection function inside the substrate structure rather than placing it on the surface. This allows the substrate surface to remain fully available for LED chip placement and optical axis alignment while the protection function operates internally.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Temperature

If high conductivity materials like aluminum nitride or high purity aluminum oxide are used, then thermal conductivity is improved, but manufacturing complexity and cost increase due to vacuum or reduction sintering requirements

Engineering Contradiction:

Improvethermal conductivityVSAvoidmanufacturing process

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The invention changes the sintering temperature parameter from high temperature (1600-1700°C vacuum sintering) to low temperature (900-1100°C atmospheric sintering). This parameter change enables the use of conventional ceramic sintering processes without requiring expensive vacuum or reduction sintering equipment, significantly simplifying manufacturing while maintaining adequate thermal conductivity through the use of aluminum oxide or aluminum nitride materials.

Inventive Principle:

Principle #35Parameter changes

3Strength

If conventional high-temperature sintering (1600-1700°C) is used to sinter overvoltage protection materials, then material density and thermal conductivity are improved, but manufacturing cost and process complexity increase significantly

Engineering Contradiction:

Improvematerial densityVSAvoidsintering process

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The invention reduces the sintering temperature parameter from 1600-1700°C to 900-1100°C and changes the atmosphere from vacuum/reduction to conventional atmospheric conditions. This parameter change enables the use of standard ceramic sintering equipment and processes, dramatically reducing manufacturing complexity and cost while still achieving sufficient material density and thermal conductivity for the application.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively protects LED chips from overvoltage and electrostatic discharge, maintains a smooth substrate surface, allows for central optical axis alignment, and enhances light extraction and heat dissipation efficiency, while simplifying the manufacturing process by avoiding high-temperature sintering.

Implementation Method 1

an overvoltage protection material embedded in each through hole... effectively protects the LED chips against overvoltage and electrostatic discharge

Methodology Applied

Scientific EffectElectrical breakdown: Avalanche Breakdown

Implementation Method 2

filling them with a high thermal conductivity overvoltage protection material... enhances light extraction and heat dissipation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

employing a metallization technique to form a flat electrode on the top and bottom sides... employing an electroplating, vacuum coating or screen-printing technique

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 4

employing an electroplating, vacuum coating or screen-printing technique to form a flat electrode

Methodology Applied

Scientific EffectVacuum coating: Physical Vapour Deposition

Data Source

PatentUS8379356B2Overvoltage protection device and its fabrication

Publication Date: 2013.02.19 HOLY STONE ENTERPRISE

AI summary

An overvoltage protection device made by: employing a machining technique to make a through hole through opposing top and bottom walls of a substrate, and then filling an overvoltage protection material in the through hole of the substrate, and then curing the overvoltage protection material, and then coating a flat electrode on each of the top and bottom walls of the substrate over and in connection with top and bottom sides of the overvoltage protection material.