LED Die-Bonding Spraying Device for Uniform Light Mixing
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Solution Overview
Problem
The traditional solder paste coating method in LED die-bonding fails to precisely control the amount of solder paste, causing the solid crystal wafer to tilt during the reflow process, which alters the light-emitting direction and deteriorates the uniformity of the surface light source.
Innovation Solution
A die-bonding method using a spraying device with a liquid circulation unit, pressurization flow-control unit, and nozzle to form a solder paste film layer on the substrate, followed by a reflow process, which includes spraying soldering flux and anti-oxidant layers to prevent tilting and improve adhesion and oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional solder paste coating method is used, then the coating process is simple, but the amount of solder paste cannot be precisely controlled causing wafer tilting
Solution Approach 1:
The patent replaces the traditional mechanical screen printing coating system with a spraying system that uses pressurized gas to atomize and deposit solder paste. This substitution enables precise control of solder paste amount through pressure and flow control, while avoiding the mechanical complexity of screen meshes and alignment mechanisms.
Solution Approach 2:
The patent employs pneumatic principles by using pressurized gas to drive the solder paste through a circulation system and nozzle for spraying. The gas pressure controls the flow rate and atomization of the solder paste, enabling precise dosage control without complex mechanical positioning systems.
2Reliability
If solder paste coating method is used, then the process is straightforward, but the solder paste pulls and drags the wafer during reflow causing light-emitting direction change
Solution Approach 1:
The patent applies preliminary action by pre-heating the substrate before spraying the solder paste. This pre-heating activates the flux and creates a receptive surface that prevents solder paste from pulling the wafer during reflow. The steel mesh is also pre-positioned to define the exact solder deposition area before the paste is applied.
Solution Approach 2:
The patent introduces a steel mesh as an intermediary element that defines the solder paste deposition area and prevents direct contact between the solder paste and the wafer during application. The mesh acts as a temporary barrier that is removed after soldering, eliminating the pulling and dragging effect on the wafer.
3Manufacturing precision
If traditional coating method is used, then the equipment is simple, but the uniformity of light mixing of the surface light source is deteriorated
Solution Approach 1:
The patent employs dynamic control of the spraying process by adjusting gas pressure, flow rate, and nozzle positioning during deposition. This dynamic adjustment ensures uniform solder paste distribution across the substrate surface, which in turn ensures uniform light mixing. The system can adapt spraying parameters in real-time to maintain consistency.
Solution Approach 2:
The patent changes multiple parameters including gas pressure, spray distance, nozzle angle, and substrate temperature to achieve uniform solder paste deposition. By optimizing these parameters, the system ensures consistent solder layer thickness and composition, which directly improves light mixing uniformity despite the increased system complexity.
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
Prevents wafer tilting and faulty soldered joints, enhancing the luminous efficiency and yield of the die-bonding operation by precisely controlling the solder paste application and ensuring uniform light mixing.
Implementation Method 1
a pressurization flow-control unit connected to the liquid circulation unit
Implementation Method 2
the pressurization flow-control unit to control an amount of spraying of the nozzle
Implementation Method 3
spraying the suspension on the pad, to form a solder paste film layer
Implementation Method 4
introducing gas into both ends of the U-shaped tube to uniformly mix the suspension
Implementation Method 5
carrying out the substrate, on which the LED is placed, to a reflow process for the solder
Data Source
AI summary
A die-bonding method and a spraying device for an LED include: providing a substrate provided with a pad and a white oil layer covering wiring, placing a steel mesh on the substrate, and then spraying suspension containing solder paste on the pad by the spraying device, to form a solder paste film layer. Finally, a reflow process for the solder is performed. The solder paste is prepared on the pad by spraying, so that a crystal wafer is prevented from being tilted or short-circuited due to pulling or dragging of the solder paste during the reflow process for the solder, thereby improving uneven brightness of the surface light source.