Thin Aluminum Alloy Foil Defect Detection via Grain Size Control
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Solution Overview
Problem
Battery packaging materials with thin aluminum alloy foil layers are prone to pinholes and cracks during molding, leading to erroneous defect determination and reduced yield in battery production, as it is difficult to distinguish fine recess and projection patterns from actual defects.
Innovation Solution
A battery packaging material with an aluminum alloy foil layer of 40 μm or less, conforming to JIS A8021 with a maximum crystal grain size of 25 μm or less and an average crystal grain size of 10 μm or less, which prevents pinholes and cracks, ensuring accurate defect determination and improved appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If the aluminum alloy foil layer thickness is reduced to achieve weight reduction and thickness reduction, then weight and thickness are improved, but pinholes and cracks are generated during molding
Solution Approach 1:
The invention changes the crystal grain size parameters of the aluminum alloy foil layer, specifying that the average crystal grain size should be 10 μm or less and the maximum crystal grain size should be 25 μm or less. This parameter change allows the foil to maintain structural integrity at reduced thickness while preventing pinholes and cracks during molding
Solution Approach 2:
The invention uses a laminated structure comprising multiple layers including the aluminum alloy foil layer, base material layer, and heat-weldable resin layer. This composite structure distributes stress during molding and prevents defect formation in the thin aluminum alloy foil layer
2Weight of stationary object
If the aluminum alloy foil layer thickness is reduced to achieve weight reduction, then weight is improved, but fine recess and projection patterns are formed on the surface
Solution Approach 1:
The invention specifies precise crystal grain size parameters (average ≤10 μm, maximum ≤25 μm) that control the surface morphology of the aluminum alloy foil during molding, preventing the formation of fine recess and projection patterns while maintaining reduced thickness
3Ease of manufacture
If conventional aluminum alloy foil is used to achieve ease of manufacture, then manufacturing simplicity is improved, but defect inspection accuracy deteriorates due to difficulty in distinguishing fine patterns from actual defects
Solution Approach 1:
By controlling the crystal grain size parameters (average ≤10 μm, maximum ≤25 μm), the invention creates a surface morphology that does not form fine recess and projection patterns, allowing defect inspection devices to accurately distinguish actual defects from surface features
Data Source
AI summary
A battery packaging material has a very thin aluminum alloy foil with a thickness of not more than 40 μm, in which pinholes or cracks are unlikely to occur during molding, which has excellent moldability and appearance after molding, which is unlikely to be erroneously determined to be a defective product, and which makes highly accurate defect determination possible. The battery packaging material includes a stacked member provided with at least, in this order: a base material layer; an aluminum alloy foil layer; and a heat sealable resin layer, wherein: the aluminum alloy foil layer has a thickness of not more than 40 μm; the aluminum alloy foil layer is an aluminum alloy conforming to JIS standard A8021; and the aluminum alloy has a maximum crystal grain size of not more than 25 μm, and an average crystal grain size of not more than 10 μm.