Sintered Joint Bonding Semiconductor Chip to Copper Surface
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Solution Overview
Problem
Conventional power electronic modules face reliability issues due to the low melting point of solder joints, which fail under high temperatures, and the cost is increased by using noble metal surfaces for joining semiconductor chips to substrates and substrates to metal baseplates, especially in harsh environments where temperatures exceed 150°C.
Innovation Solution
A sintered joint bonding method is used to directly join semiconductor chips to copper surfaces and copper layers without noble metal layers, employing a low temperature joining process that uses a bonding paste or slurry with specific particle sizes and a non-oxidizing atmosphere to prevent oxidation and ensure strong, cost-effective connections suitable for temperatures up to and exceeding 200°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soft soldering with Sn-Pb, Sn-Ag, or Sn-Ag-Cu alloy is used to join semiconductor chips to substrates, then the joining process is simple and cost-effective, but the solder joints fail under high temperatures above 150°C due to low melting point and thermal cycling
Solution Approach 1:
The invention changes the material composition parameters by replacing traditional solder alloys (Sn-Pb, Sn-Ag, Sn-Ag-Cu) with a copper-based sintering paste containing Cu powder, organic vehicle, and sintering aids. This parameter change enables the joint to withstand temperatures above 150°C while maintaining reliability through direct copper bonding mechanism rather than melting-point-limited soldering
Solution Approach 2:
The invention replaces the thermal-mechanical soldering process (which relies on melting and solidification) with a sintering process that uses diffusion bonding at lower temperatures. The sintering paste forms a metallurgical bond through copper diffusion and oxidation-reduction reactions, eliminating the melting point constraint of traditional solders
2Reliability
If noble metal surfaces are used for joining semiconductor chips to substrates and substrates to metal baseplates, then the joining strength and reliability are improved, but the manufacturing cost increases significantly
Solution Approach 1:
The invention replaces expensive noble metals (such as Au, Ag, Pd plating) with a cost-effective copper-based sintering paste. The paste contains Cu powder and organic binders that are consumed during the sintering process to form strong copper-to-copper bonds, eliminating the need for costly noble metal layers while maintaining joining reliability
Solution Approach 2:
The invention uses copper surfaces on both the substrate and the semiconductor chip mounting surface, creating homogeneous copper-to-copper joints. This eliminates the need for dissimilar metal bonding (e.g., solder to copper, or noble metal to copper) and enables direct metallurgical bonding through the sintering process, reducing material costs and process complexity
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 solution enhances the thermal cycling reliability and reduces costs by eliminating the need for noble metals, enabling power electronic modules to operate reliably at high temperatures while maintaining structural integrity and preventing oxidation during the sintering process.
Implementation Method 1
a first sintered joint bonding the semiconductor chip directly to the first copper surface
Implementation Method 2
a non-oxidizing atmosphere to prevent oxidation and ensure strong, cost-effective connections
Data Source
AI summary
A module includes a substrate including a first copper surface and a semiconductor chip. The module includes a first sintered joint bonding the semiconductor chip directly to the first copper surface.