Submount-free LED Components Direct PCB Soldering
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Solution Overview
Problem
Conventional Light Emitting Diodes (LEDs) require a submount or interposer to connect to a printed circuit board, which increases cost, size, and complexity, and alters contact configurations, while also necessitating additional components like submounts for phosphor layers or encapsulation.
Innovation Solution
The use of a solder mask on the LED chip's contacts to create a larger gap for improved compatibility with printed circuit board pads, eliminating the need for a submount by directly soldering the LED chip to the board without an intervening submount, and applying a phosphor layer and transparent layer on the chip before soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a submount or interposer is used to connect LED to printed circuit board, then connection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the submount or interposer component from the LED assembly, eliminating the intermediate connection layer. The LED chip is directly soldered to the printed circuit board pads, extracting the unnecessary submount element that added complexity and cost while not providing essential functional benefits.
Solution Approach 2:
The patent merges the LED chip mounting function directly with the printed circuit board by establishing direct solder connections between the LED contacts and board pads. This combines what were previously separate functions (submount support and electrical connection) into a single integrated structure, reducing overall device complexity.
2Stability of the object's composition
If a submount is used to support phosphor layer or encapsulation, then structural stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent eliminates the submount component that was previously required to support the phosphor layer and encapsulation structure. By redesigning the contact configuration and solder mask pattern, the LED chip can be directly mounted on the PCB while maintaining proper support for optical components, removing an unnecessary manufacturing step.
Solution Approach 2:
The patent applies the solder mask pattern and designs the contact configuration in advance to ensure proper structural support and alignment before mounting. The solder mask extends onto the contact surfaces to provide mechanical support and define precise solder joint locations, eliminating the need for post-mounting submount attachment.
3Adaptability or versatility
If submount is used, then contact configuration flexibility is improved, but cost increases
Solution Approach 1:
The patent replaces the expensive submount component with a simpler, more cost-effective direct solder connection approach. The solder mask and contact pattern design provide the necessary configuration flexibility without requiring additional expensive intermediate components, reducing material costs while maintaining adaptability.
Solution Approach 2:
The patent designs the solder mask and contact configuration to serve multiple functions simultaneously: providing electrical connection, defining mechanical alignment, supporting the phosphor layer, and enabling various contact patterns (anode-cathode spacing variations). This multi-functionality eliminates the need for separate submount components that would add cost.
4Manufacturing precision
If solder mask extends onto contact outer faces, then soldering precision is improved, but manufacturing complexity increases
Solution Approach 1:
The solder mask is applied in advance during the LED chip fabrication process, extending onto the outer faces of the contacts before mounting. This pre-application of the solder mask defines precise solder joint locations and protects non-solder areas, improving soldering precision while integrating the masking step into the existing manufacturing flow rather than adding a separate complex process.
Solution Approach 2:
The patent combines the solder mask function with the contact structure itself by extending the mask onto the contact outer faces. This integration merges the protective and precision-defining functions of the solder mask with the electrical contact structure, eliminating the need for separate alignment and masking steps that would increase device complexity.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Light emitting devices include a Light Emitting Diode (LED) chip having an anode contact and a cathode contact on a face thereof. A solder mask extends from the gap between the contacts onto one or both of the contacts. The LED chip may be mounted on a printed circuit board without an intervening submount. Related fabrication methods are also described.