Silver Oxide Die Attach for LED Thermal Management
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Solution Overview
Problem
Conventional die-attach methods for semiconductor elements, such as resin bonding and eutectic bonding, face issues with thermal degradation, poor thermal conductivity, and light extraction efficiency, particularly in light emitting diodes and laser diodes, due to the use of epoxy resins and eutectic metals, which lead to reliability and cost concerns.
Innovation Solution
A method involving the direct bonding of silver or silver oxide-coated surfaces on a semiconductor element and a base using heat between 200°C to 900°C in an air or oxygen environment, eliminating the need for intermediate bonding materials and enhancing thermal conductivity and light reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If resin bonding is used for mounting semiconductor elements, then the bonding process can be performed at low temperatures (150-200°C), but the resin deteriorates over time due to heat generation, causing discoloration and bonding strength deterioration
Solution Approach 1:
The invention changes the bonding temperature parameter from low temperature (150-200°C for resin bonding) to high temperature (300°C or higher for eutectic bonding). This parameter change allows the use of eutectic metals instead of resin, which do not deteriorate over time due to heat generation, thereby resolving the contradiction between low bonding temperature and long-term reliability.
Solution Approach 2:
The invention replaces the durable but heat-sensitive resin bonding material with eutectic metal bonding that can withstand high temperatures and long-term operation. The eutectic bonding creates a permanent, non-deteriorating bond that eliminates the need for replacement due to bonding material degradation.
2Ease of manufacture
If resin bonding is used for mounting semiconductor elements, then the bonding process is simple and convenient, but the resin has poor thermal conductivity and insufficient heat releasability
Solution Approach 1:
The invention changes the bonding material from resin to eutectic metal, which fundamentally alters the thermal conductivity parameter. Eutectic metals provide excellent thermal conductivity and heat releasability, resolving the contradiction by enabling efficient heat dissipation while maintaining a relatively simple bonding process through the use of eutectic alloys.
3Reliability
If eutectic bonding is used for mounting semiconductor elements, then the bonding strength and heat releasability are improved, but the bonding process requires high temperatures (300°C or greater) that cannot be withstood by resin packages
Solution Approach 1:
The invention applies local quality by providing heat-resistant coating only in the specific bonding area where high temperature is required, while the rest of the package can remain as standard resin material. This localized heat-resistant structure allows eutectic bonding to be performed at high temperatures without requiring the entire package to be heat-resistant.
4Reliability
If eutectic bonding is used for mounting light emitting diodes, then the bonding strength is improved, but the light extraction effect cannot be enhanced since eutectic metals have poor reflectivity
Solution Approach 1:
The invention uses composite materials by combining eutectic metal for bonding strength with silver plating for light reflectivity. The eutectic metal layer provides strong mechanical bonding, while the silver layer enhances light extraction effect through its high reflectivity, resolving the contradiction between bonding strength and light extraction performance.
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
This approach provides a reliable, cost-effective semiconductor device with improved heat dissipation and light emission efficiency, extending the device's lifespan and simplifying the production process while avoiding thermal deterioration of plastic components.
Implementation Method 1
silver oxide provided on at least either one of a surface of the base and a surface of the semiconductor element
Implementation Method 2
bonding the semiconductor element and the base by applying heat having a temperature of 200 to 900°C
Implementation Method 3
arranging the semiconductor element on the base such that silver or silver oxide provided on a surface of the semiconductor element is in contact with silver or silver oxide provided on a surface of the base
Implementation Method 4
silver plating, which has high light reflectivity, is provided over the surface of a wiring board or a lead frame
Implementation Method 5
since they have poor thermal conductivity and insufficient heat releasability
Data Source
Figure 1~3
AI summary
An object of the invention is to provide a method for producing a conductive member having low electrical resistance, and the conductive member is obtained using a low-cost stable conductive material composition that does not contain an adhesive. A method for producing a semiconductor device in which silver or silver oxide provided on a surface of a base and silver or silver oxide provided on a surface of a semiconductor element are bonded, includes the steps of arranging a semiconductor element on a base such that silver or silver oxide provided on a surface of the semiconductor element is in contact with silver or silver oxide provided on a surface of the base, and bonding the semiconductor element and the base by applying heat having a temperature of 200 to 900°C to the semiconductor device and the base.