Porous Metal Joining Layer to Suppress Oozing and Voids
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Solution Overview
Problem
Existing techniques for joining two members using a joining material face challenges in suppressing the decrease in joint strength due to oozing of the joining material and generation of voids at the joint interfaces.
Innovation Solution
A joined body configuration where a first member and a second member are joined via a joining layer containing a metal with a surface tension of 1000 mN/m or less at its melting point, and a metal layer with pores impregnated with the joining material, which suppresses oozing and void generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a joining material containing indium is used to join two members, then the joining material can spread over wide regions of joint interfaces, but the joining material may ooze from between the two members causing decreased joint strength
Solution Approach 1:
A porous layer is introduced between the two members in the joining structure. This porous layer acts as a barrier to contain the joining material within the joint interface region, preventing it from oozing out while still allowing it to spread widely across the interface for strong bonding. The porous structure provides capillary action to distribute the joining material evenly without excessive flow.
Solution Approach 2:
The joining structure comprises a composite of multiple layers including the two members, joining material, and porous layer. This composite structure combines the low surface tension properties of indium-based joining material with the containment properties of the porous layer, achieving both wide spread area and prevented oozing simultaneously.
2Strength
If fibers are added to the joining layer to hinder flow of joining material, then oozing is suppressed, but voids are generated at the joint interfaces causing decreased joint strength
Solution Approach 1:
The porous layer provides a controlled porous structure that differs from discrete fibers. The continuous porous network allows the joining material to flow uniformly through capillary action without being blocked by individual fiber obstacles, thereby preventing void formation at interfaces while still suppressing oozing through the overall porous barrier effect.
3Strength
If a mesh member is added to the joining layer to hinder flow of joining material, then oozing is suppressed, but voids are generated at the joint interfaces causing decreased joint strength
Solution Approach 1:
The porous layer provides a fine-grained porous structure with much smaller pore sizes compared to mesh members. This fine porous structure allows uniform distribution of joining material through capillary action without creating large void spaces, whereas mesh members create large open spaces that trap voids at the joint interfaces.
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 suppresses oozing of the joining material and generation of voids, thereby maintaining or increasing the joint strength between the two members.
Implementation Method 1
a metal layer which has a plurality of pores formed therein and in which at least some of the pores are impregnated with the joining material
Data Source
AI summary
A joining layer of a joined body includes a joining material which contains, as a main component, a metal having a surface tension of 1000 mN/m or less at its melting point, and a metal layer which has a plurality of pores formed therein and in which at least some of the pores are impregnated with the joining material.