3D Electrode Layout in LED Packages to Block Solder Intrusion
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Solution Overview
Problem
Semiconductor light emitting devices face challenges in minimizing size while preventing unwanted electrical connections due to solder intrusion, which is often addressed by using insulating films that increase the device's size.
Innovation Solution
The semiconductor light emitting device features a board with a first electrode comprising a first bonding portion, a first portion, and a second portion on the principal surface, and a third portion on a different surface, ensuring electrical continuity without the need for insulating films, thereby preventing solder intrusion and reducing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating films are formed on the principal surface to prevent solder intrusion, then reliability is improved, but the device size increases
Solution Approach 1:
The patent moves the electrode structure from a two-dimensional planar configuration to a three-dimensional configuration by extending portions of the electrode to the back surface of the board. This dimensional change allows the electrode to achieve both solder protection and electrical continuity without requiring additional insulating films that would increase the device's planar area.
Solution Approach 2:
The electrode is segmented into multiple functional portions: a first bonding portion on the front surface for mounting the light emitting element, second and third portions extending to the back surface for solder connection, and a fourth portion for electrical continuity. This segmentation allows each portion to perform its specific function efficiently, achieving solder intrusion prevention while maintaining compact size.
2Area of stationary object
If the electrode structure is extended to ensure electrical continuity without insulating films, then device size is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into the single electrode structure: mounting function (first bonding portion), solder connection function (second and third portions), and electrical continuity function (fourth portion). By merging these functions into one integrated electrode rather than using separate components and insulating films, the overall device complexity is reduced despite the extended geometry.
3Reliability
If portions of the electrode are disposed apart from each other on the principal surface, then solder intrusion is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The patent resolves the positioning precision challenge by extending electrode portions from the front surface to the back surface of the board. This three-dimensional arrangement naturally separates the electrode segments in space, preventing solder intrusion paths while maintaining manufacturable precision requirements through the board's thickness dimension.
Data Source
AI summary
A semiconductor light emitting device includes a board including a first principal surface facing a first side in a thickness direction thereof, a first electrode provided on the board, a semiconductor light emitting element, and a light-transmitting resin that covers the element. The first electrode includes a first bonding portion and first, second, and third portions. The first bonding portion is formed on the first principal surface and is joined and electrically connected to the element. The first and second portions are each formed on the first principal surface and disposed on a first side in a first direction. The first portion is connected to the first bonding portion. The second portion is apart from the first bonding portion, and from the first portion in a second direction. The third portion is formed on a place different from the first principal surface, electrically connecting the first and second portions to each other.