Joint Structure With Thin Intermetallic Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The joint structure between electronic components and wiring substrates is brittle and prone to breakage due to the formation of hard intermetallic compounds, which reduces its flexibility and increases the risk of failure under stress.
Innovation Solution
A joint structure is designed with a thin intermetallic compound layer (0.1 μm to 0.5 μm thick) between layers of Sn and metals like Au, Cu, Ni, or Ag, which are ductile, to enhance breakage strength and reliability by preventing bending and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an intermetallic compound layer is formed at the joint interface, then the joint structure becomes harder and more resistant to bending, but the joint structure becomes more brittle and prone to breakage
Solution Approach 1:
The patent changes the thickness parameter of the intermetallic compound layer from conventional thicker dimensions to a controlled range of 0.1-0.5 μm. This parameter modification allows the layer to provide sufficient hardness and bending resistance while minimizing brittleness and breakage risk, thus resolving the technical contradiction between strength and reliability.
Solution Approach 2:
The patent creates a composite joint structure consisting of multiple layers: a first metal layer (Sn-containing), an intermetallic compound layer (0.1-0.5 μm thick), and a second metal layer. This composite structure combines the hardness of the intermetallic compound with the ductility of the metal layers, achieving both bending resistance and breakage resistance simultaneously.
2Reliability
If the intermetallic compound layer is made thinner to reduce brittleness, then the joint structure becomes more flexible, but the ability to resist bending decreases
Solution Approach 1:
The patent identifies and optimizes the critical thickness parameter of the intermetallic compound layer, setting it within the specific range of 0.1-0.5 μm. This precise parameter control ensures the layer is thin enough to maintain flexibility and reduce brittleness, yet thick enough to provide adequate bending resistance, thereby resolving the contradiction between reliability and strength.
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 joint structure achieves high breakage strength and reliability by sandwiching a thin intermetallic compound layer between ductile metals, reducing the likelihood of bending and cracking, and thus minimizing defects during assembly processes like in LED displays.
Implementation Method 1
an intermetallic compound of Au and Sn tends to be formed at a joint interface due to eutectic reaction
Implementation Method 2
the metals are soft materials that are generally ductile since the metals have metallic bonding
Data Source
AI summary
A joint structure, in which an electronic component and a wiring substrate are joined to each other, includes: a first layer being provided on one side of the electronic component and the wiring substrate, and being composed of a first metal containing Sn; a second layer being provided on the other side of the electronic component and the wiring substrate, and being composed of a second metal that forms an intermetallic compound with Sn; and a third layer being provided at a joint interface between the first layer and the second layer, and being composed of an intermetallic compound of the first metal and the second metal. An average thickness of the third layer is 0.1 μm or more to 0.5 μm or less.