Semiconductor Light Emitting Chip Electrodes for Lower Thermal Resistance
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Solution Overview
Problem
CSP type semiconductor light emitting devices face issues with increased thermal resistance and assembly tolerance due to smaller pad electrodes, and the adhesion between encapsulation layers and electrodes is compromised during high-temperature processes, leading to potential short-circuits and peeling off of electrodes.
Innovation Solution
The semiconductor light emitting device features first electrodes with larger planar areas than the chip, with exposed lower surfaces and an insulating material filled between their inner lateral surfaces, and a method involving a sacrificial substrate for manufacturing, where the sacrificial substrate is removed to expose the electrodes externally, reducing thermal resistance and improving adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the pad electrode size is reduced to achieve smaller CSP package size, then the device size is reduced, but the thermal resistance increases and assembly tolerance deteriorates
Solution Approach 1:
The patent extends the electrode structure vertically by forming protruding portions that extend downward from the encapsulation layer. This dimensional extension allows the electrode to make contact with the substrate at a lower position, effectively increasing the thermal conduction path length without increasing the horizontal package footprint, thus resolving the contradiction between small package size and thermal management.
Solution Approach 2:
The electrode structure is segmented into multiple functional portions: a first portion within the encapsulation layer for electrical connection, and protruding portions extending downward for thermal conduction and mechanical anchoring. This segmentation allows each portion to optimize its function independently, improving overall reliability without increasing package size.
2Ease of manufacture
If high-temperature processes are used during manufacturing, then the encapsulation layer is formed, but the adhesion between encapsulation layer and electrode deteriorates causing peeling and short-circuits
Solution Approach 1:
The electrode protruding portions are formed to extend below the encapsulation layer before or during the encapsulation process. This preliminary structural preparation ensures that the electrode has mechanical anchoring points established before high-temperature processing occurs, preventing adhesion deterioration and peeling during subsequent manufacturing steps.
Solution Approach 2:
The downward-extending protruding portions act as a cushioning mechanism that compensates for the adhesion weakness caused by high-temperature processing. By providing mechanical interlocking below the encapsulation layer, the structure preemptively counteracts the potential for peeling and short-circuits that would otherwise occur during or after high-temperature encapsulation.
Data Source
AI summary
The semiconductor light emitting device comprises a semiconductor light emitting chip, and first electrodes electrically connected to the semiconductor light emitting chip, with the first electrodes each having a planar area larger than that of the semiconductor light emitting chip, wherein lower surfaces of the first electrodes are exposed externally, and an insulating material is filled in-between inner lateral surfaces of the first electrodes.