LED Carrier Assembly Embedded Alignment Magnet
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Solution Overview
Problem
The existing methods for mounting LEDs onto carriers using solder face challenges such as limited junction temperature, thermal shock reliability, misalignment, and coefficient of thermal expansion mismatches between LEDs and PCBs, leading to potential detachment and reduced product lifetime.
Innovation Solution
A method employing a carrier with embedded magnets to align and securely hold magnetic die pads of LEDs in place, establishing a solderless electrical and thermal connection through magnetic forces, allowing for precise alignment and reduced stress from thermal expansion mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If solder is used to bond LED die to PCB, then electrical and thermal connection is achieved, but junction temperature is limited and thermal shock reliability decreases
Solution Approach 1:
The patent extracts the solder bonding function and replaces it with a magnetic bonding system. The LED carrier assembly includes a magnet that magnetically attracts the LED die, eliminating the need for solder. This allows the LED to operate at higher junction temperatures without solder melting, and prevents thermal shock reliability issues since there is no solder joint to crack during temperature cycling.
Solution Approach 2:
The patent replaces the mechanical solder bonding system with a magnetic field-based bonding system. Instead of using molten solder that solidifies to create a rigid mechanical bond, the invention uses magnetic attraction forces to hold the LED die in place. This substitution eliminates the thermal and mechanical limitations of solder while maintaining the electrical and thermal connection functions.
2Manufacturing precision
If solder bonding is used for LED mounting, then electrical connection is established, but misalignment occurs in X, Y, and Z dimensions
Solution Approach 1:
The patent applies preliminary action by pre-magnetizing the LED die or the carrier before the bonding process. The magnet is already in place on the carrier, and the LED die is pre-prepared with magnetic properties. When the LED die is placed near the carrier, the magnetic attraction immediately pulls it into precise alignment with the intended position, eliminating the alignment uncertainties inherent in soldering processes.
3Reliability
If rigid solder bond is used to connect LED to PCB, then electrical connection is achieved, but CTE mismatch causes physical stress and reduced lifetime
Solution Approach 1:
The patent changes the fundamental parameter of the bonding mechanism from rigid mechanical solder bonding to flexible magnetic attraction. The magnetic bond allows for relative movement between the LED die and carrier due to CTE mismatch, as magnetic force can accommodate positional changes without creating stress concentrations. This parameter change from rigid to flexible bonding preserves bond strength while eliminating the stress caused by differential thermal expansion.
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
This approach eliminates solder-related issues, enabling higher junction temperature tolerance, improved thermal shock reliability, precise alignment, and reduced material costs by using cheaper LEDs, while simplifying the assembly process and enhancing the accuracy of LED placement.
Implementation Method 1
embedding a magnet below the mounting surface of the carrier; aligning the magnetic die pads of an LED die to mounting pads by arranging the LED die on the mounting surface of the carrier within magnetic range of a magnet
Data Source
AI summary
The invention describes a method of manufacturing an LED carrier assembly, which method comprises the steps of providing a carrier comprising a mounting surface with mounting pads arranged to receive a number of LED dies; embedding an alignment magnet in the carrier; providing a number of LED dies, wherein an LED die comprises a number of magnetic die pads; and aligning the magnetic die pads to the mounting pads by arranging the LED dies over the mounting surface of the carrier within magnetic range of the alignment magnet. The invention also describes an LED carrier assembly.