Light Emitting Device Multi-Layer Conductive Patterns
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Solution Overview
Problem
The existing light emitting devices face reliability issues due to poor connections between light emitting elements and external power feed members, particularly under high electrical power applications, caused by the combination of conductive patterns and power feed members.
Innovation Solution
A light emitting device design featuring a mounting board with conductive patterns comprising multiple layers of different materials, where the first conductive layers are exposed at the element mounting areas and the second conductive layers are used for external connectors, ensuring secure connections and improved reliability by using materials like gold for the first layers and aluminum for the second layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive patterns are used as external electrodes with wire or power feed member connected, then electrical connection is established, but long-term application of high levels of electrical power may result in poor connection
Solution Approach 1:
The conductive pattern is segmented into multiple layers with different materials: a first conductive layer (e.g., aluminum) for electrical conduction and a second conductive layer (e.g., gold) for reliable external connection. This segmentation allows each layer to perform its optimal function, preventing connection degradation under high power application.
Solution Approach 2:
The conductive pattern uses composite material structure combining different conductive materials in layers. The first conductive layer provides cost-effective bulk conduction while the second conductive layer provides oxidation-resistant, reliable external connection surfaces, together solving the long-term reliability issue under high electrical power.
2Ease of operation
If conductive patterns extend outside scaling member for external connection, then external power supply connection is enabled, but connection quality deteriorates under high electrical power
Solution Approach 1:
Different regions of the conductive pattern have different material compositions: the first conductive layer extends throughout for conduction, while the second conductive layer is applied specifically at the external connection regions. This local quality differentiation ensures reliable connections where needed while maintaining overall electrical performance.
Data Source
AI summary
A light emitting device includes an element mounting board including a base, a set of conductive patterns, one or more light emitting elements, and a cover member. The set of conductive patterns includes one or more first conductive layers and one or more second conductive layers made of a different material. The second conductive layers partially cover the first conductive layers. The set of conductive patterns defines one or more element mounting areas each including a part of the first conductive layers not covered by the second conductive layers, and external connectors each including one or more outer edge exposed parts where a part of an outer edge of a corresponding one of the first conductive layers is exposed from the second conductive layers. The cover member covers the light emitting elements and the element mounting areas. The cover member is spaced apart from the outer edge exposed parts.