Sn-Cu Preform with Intermetallics for SiC Encapsulation
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Solution Overview
Problem
Current semiconductor encapsulation methods, using either resin or Sn-based solder, fail to provide sufficient heat resistance and reliability for SiC semiconductor elements, especially under high-temperature and temperature-changing environments, limiting their performance and durability.
Innovation Solution
A preform for semiconductor encapsulation composed of Sn or Sn alloy and Cu or Cu alloy, with at least 2% by weight of intermetallic compounds like Cu3Sn and Cu6Sn5, which forms a sealing layer with elevated re-melting temperature and reduced surface tension, eliminating the need for flux and preventing void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resin encapsulant is used as sealing layer, then ease of manufacture is improved, but heat resistance deteriorates (degrades above 150°C)
Solution Approach 1:
The patent uses a composite material consisting of Sn-based solder as the base matrix and intermetallic compounds (such as Cu3Sn, Cu6Sn5, FeSn2, CoSn5, Ni3Sn4, or AlSn3) as dispersed phases. This composite structure combines the low melting point and ease of processing of Sn-based solder with the high heat resistance of intermetallic compounds, enabling the sealing layer to maintain both manufacturability and thermal stability above 150°C.
2Ease of manufacture
If Sn-based solder is used as metal encapsulant, then ease of manufacture is improved, but heat resistance deteriorates (melting temperature 200-230°C insufficient for power devices)
Solution Approach 1:
The patent uses a composite material consisting of Sn-based solder as the base matrix and intermetallic compounds (such as Cu3Sn, Cu6Sn5, FeSn2, CoSn5, Ni3Sn4, or AlSn3) as dispersed phases. This composite structure combines the low melting point and ease of processing of Sn-based solder with the high heat resistance of intermetallic compounds, enabling the sealing layer to maintain both manufacturability and thermal stability above 150°C.
Solution Approach 2:
The patent changes the physical and chemical parameters of the Sn-based solder by controlling the content of intermetallic compounds to be 0.1-10 wt% (preferably 0.5-5 wt%). This parameter adjustment modifies the melting characteristics and thermal stability of the sealing layer, enabling it to resist temperatures above 150°C while maintaining ease of manufacture.
3Ease of manufacture
If Sn-based solder is used as sealing layer, then ease of manufacture is improved, but reliability deteriorates (void formation after prolonged high-temperature operation)
Solution Approach 1:
The patent uses a composite material consisting of Sn-based solder as the base matrix and intermetallic compounds (such as Cu3Sn, Cu6Sn5, FeSn2, CoSn5, Ni3Sn4, or AlSn3) as dispersed phases. This composite structure combines the low melting point and ease of processing of Sn-based solder with the high heat resistance of intermetallic compounds, enabling the sealing layer to maintain both manufacturability and thermal stability above 150°C.
Solution Approach 2:
The patent incorporates intermetallic compounds into the Sn-based solder before the sealing process. These intermetallic compounds act as preventive measures that cushion against the formation of voids during prolonged high-temperature operation, thereby maintaining reliability without compromising ease of manufacture.
4Device complexity
If resin encapsulant is used as sealing layer, then device complexity is reduced, but heat resistance deteriorates (limits SiC semiconductor element performance)
Solution Approach 1:
The patent uses a composite material consisting of Sn-based solder as the base matrix and intermetallic compounds (such as Cu3Sn, Cu6Sn5, FeSn2, CoSn5, Ni3Sn4, or AlSn3) as dispersed phases. This composite structure combines the low melting point and ease of processing of Sn-based solder with the high heat resistance of intermetallic compounds, enabling the sealing layer to maintain both manufacturability and thermal stability above 150°C.
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 preform achieves high heat resistance and reliability by forming a robust sealing layer at lower temperatures, preventing damage to semiconductor elements and enhancing the durability and performance of SiC semiconductor devices.
Implementation Method 1
a preform for semiconductor encapsulation which mainly includes a metal or alloy, the metal or alloy further includes Sn or Sn alloy, and, Cu or Cu alloy, and still further includes at least 2% by weight of an intermetallic compound of Cu and Sn
Implementation Method 2
forms a sealing layer with elevated re-melting temperature and reduced surface tension, eliminating the need for flux and preventing void formation
Data Source
AI summary
Disclosed is a preform for semiconductor encapsulation, mainly containing a metal or alloy, the metal or alloy further containing Sn or Sn alloy, and, Cu or Cu alloy, and still further containing at least 2% by weight of an intermetallic compound of Cu and Sn.