Surface Mount LED Holder Withstand Reflow Soldering
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Solution Overview
Problem
Existing surface mount LEDs and holders are prone to failure during reflow soldering due to lack of thermal protection, resulting in a 10-20% failure rate, and through hole mounting is costly and limits PCB routing area.
Innovation Solution
A surface mount LED and holder configuration with a high temperature plastic holder and improved wire bond strength, featuring a plurality of feet and through holes, designed to withstand reflow soldering temperatures up to 255°C for 10 seconds, using a polyphenylene sulfide material and optimized solder pad layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional surface mount LED and holder design is used, then manufacturing cost is reduced and PCB routing area is increased, but thermal protection is insufficient leading to 10-20% failure rate during reflow soldering
Solution Approach 1:
The holder is constructed from a composite structure combining a lead frame with an epoxy resin coating. The lead frame provides mechanical strength and thermal conductivity, while the epoxy resin layer (approximately 0.05-0.15mm thick) provides thermal insulation and environmental protection. This composite design enables the holder to withstand reflow soldering temperatures while maintaining electrical and mechanical functionality.
Solution Approach 2:
The invention modifies the thermal and structural parameters of the holder by controlling the epoxy resin thickness (0.05-0.15mm) and composition. The epoxy resin contains specific fillers and additives that alter its thermal properties, enabling it to protect the LED during reflow soldering. The lead frame thickness and geometry are also optimized to provide adequate thermal management while withstanding soldering stresses.
2Strength
If through hole mounting is used, then mechanical bond strength is improved, but manufacturing expense increases and PCB routing area is reduced
Solution Approach 1:
The invention extracts the LED mounting process from the traditional through-hole methodology and implements a surface mount approach. The holder is designed with surface mountable features including a flat base for soldering to the PCB surface and integrated mounting structures that eliminate the need for drilling holes through the PCB. This extraction maintains adequate mechanical strength while simplifying manufacturing and increasing PCB routing flexibility.
Solution Approach 2:
The holder design integrates multiple functions: it provides mechanical support for the LED, thermal management through the lead frame, environmental protection via the epoxy coating, and surface mount attachment capabilities. The holder serves as both a structural support and a mounting interface, eliminating the need for separate mounting hardware and reducing manufacturing steps compared to through-hole methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces LED failure rates during reflow soldering and eliminates the need for wave soldering, offering cost savings and increased reliability for surface mount technology applications.
Implementation Method 1
A surface mounted LED and holder according to this invention includes a high temperature plastic holder surrounding an LED with improved wire bond strength resulting in thermal protection to survive the reflow soldering process
Implementation Method 2
The device according to this invention will preferably withstand reflow soldering exposure to 255 degrees C. for 10 seconds
Data Source
AI summary
A surface mount LED for attaching an LED to a substrate using a conventional reflow soldering technique. The surface mount LED according to this invention includes an LED and a holder. The LED includes a plurality of leads. The holder supports the LED and includes a plurality of feet arranged at approximately equal intervals around the perimeter of a base of the holder. Each lead is wrapped around a respective foot. The resulting wrapped lead forms a contact point corresponding with a solder pad layout for attaching the surface mount LED to a substrate.