Semiconductor Light Emitting Device Electrode Pad Extension
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Solution Overview
Problem
Conventional semiconductor light emitting devices face challenges in reducing thickness due to short-circuit issues caused by silver paste rising onto the LED chip when thin LED chips are used, leading to increased device thickness.
Innovation Solution
A semiconductor light emitting device design featuring a substrate with electrodes and a die bonding pad where the outer edge of the pad is positioned inside the LED chip, and extensions on the electrodes to contain the electrically conductive paste, preventing it from rising onto the chip's surface, allowing for a thinner LED chip and reduced device thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the LED chip thickness is reduced to achieve device thickness reduction, then the device thickness is reduced, but the silver paste may rise onto the upper surface of the LED chip causing a short-circuit
Solution Approach 1:
The die bonding pad is designed with an extension that protrudes beyond the LED chip in the planar direction (horizontal dimension), creating a dimensional extension that provides a containment area for excess silver paste. This prevents the paste from rising vertically onto the LED chip surface, thus resolving the short-circuit risk while maintaining thin LED chip design.
Solution Approach 2:
The extension of the die bonding pad acts as an intermediary structure between the silver paste and the LED chip. It provides a designated area for the paste to spread into, serving as a buffer zone that prevents direct contact between the paste and the LED chip upper surface, thereby eliminating the short-circuit hazard.
2Length of stationary object
If a thin LED chip is employed, then the device thickness is reduced, but the electrically conductive paste spreads out of control and rises onto the chip surface
Solution Approach 1:
The die bonding pad extends in the horizontal plane beyond the LED chip boundaries, providing a two-dimensional containment area. This planar extension creates a physical boundary that guides and limits the spread of silver paste, preventing uncontrolled vertical rise onto the chip surface while accommodating thin LED chip designs.
3Manufacturing precision
If the outer edge of the die bonding pad is positioned inside the LED chip, then paste spread is suppressed, but the electrode structure becomes more complex
Solution Approach 1:
The die bonding pad is segmented into two functional zones: a main bonding area within the LED chip boundaries for primary electrical connection, and an extension area protruding beyond the chip for paste containment. This segmentation allows the electrode structure to serve dual purposes - electrical bonding and paste management - without requiring entirely separate components.
Solution Approach 2:
The extended die bonding pad structure performs multiple functions simultaneously: it provides the electrical bonding function within the LED chip area and serves as a paste containment barrier extending beyond the chip. This multi-functionality reduces the need for additional separate structures, thereby managing complexity while achieving paste control.
Data Source
AI summary
A semiconductor light emitting device (A1) includes a substrate (1) and two electrodes (2A, 2B) formed on the substrate (1). The electrode (2A) is formed with a die bonding pad (2Aa), to which an LED chip (3) is bonded by silver paste (6). The outer edge of the die bonding pad (2Aa) is positioned on the inner side of the outer edge of the LED chip (3) as viewed in the thickness direction of the substrate (1). The electrode (2A) is formed with an extension (21) extending from the die bonding pad (2Aa) to the outside of the LED chip (3).