Laser Bonding Control for Reflow-Safe LED Die Attachment
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Solution Overview
Problem
Existing laser bonding methods for semiconductor elements on substrates face issues with process defects due to the reflow of bonding members during laser bonding, which can lead to inefficiencies and reliability concerns.
Innovation Solution
A laser bonding device and method that includes a control unit to manage laser power and time based on temperature and pressure sensors, using a table to determine the state of the bonding member, and adjusting laser power and pressure levels to minimize reflow, with a flux application and cleaning process to reduce defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser bonding is performed with high power and pressure to ensure reliable bonding, then bonding strength is improved, but reflow of bonding members occurs causing process defects
Solution Approach 1:
The patent applies dynamics by making the laser power and pressure variable during the bonding process. The control unit dynamically adjusts laser power in stages (first power level, then second power level) and adjusts pressure based on temperature feedback from the bonding member. This dynamic adjustment prevents reflow while ensuring reliable bonding, resolving the contradiction between bonding strength and bonding precision.
Solution Approach 2:
The patent changes physical parameters (laser power, pressure, temperature) in a controlled sequence. Laser power is changed from a first level to a second level during the process, and pressure is adjusted based on temperature measurements. These parameter changes enable achieving strong bonding without causing reflow defects.
2Productivity
If laser power is increased to reduce bonding time, then productivity is improved, but temperature control becomes difficult causing defects
Solution Approach 1:
The patent implements feedback control by using a temperature sensor to measure the temperature of the bonding member in real-time and feeding this information back to the control unit. The control unit adjusts laser power and pressure based on this feedback, maintaining temperature within a safe range while achieving fast bonding, thus improving both productivity and reliability.
Solution Approach 2:
The patent uses periodic action by applying laser irradiation in stages with different power levels. A first laser power level is applied initially, then a second power level is applied subsequently based on temperature conditions. This periodic application of different power levels enables fast bonding while maintaining temperature control for reliability.
3Manufacturing precision
If pressure is increased to improve bonding quality, then manufacturing precision is improved, but the bonding member may deform or reflow
Solution Approach 1:
The patent applies dynamics by making pressure variable rather than constant. The control unit adjusts pressure based on real-time temperature measurements from the bonding member. Pressure is applied at appropriate levels at different stages of the bonding process, ensuring high bonding quality without causing deformation or reflow of the bonding member.
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 effectively reduces process defects in laser bonding by controlling laser power and pressure, ensuring reliable bonding of semiconductor elements to substrates, thereby enhancing the integrity and performance of the bonding process.
Implementation Method 1
a laser generating unit configured to irradiate a laser beam to a bonding member for bonding the light emitting element and the substrate
Implementation Method 2
a temperature sensor configured to measure the temperature of the bonding member
Implementation Method 3
a pressurized head module configured to fix a light emitting element as a bonding object
Data Source
AI summary
A laser bonding device includes: a support unit configured to fix a substrate thereon; a pressurized head module configured to fix a light emitting element as a bonding object; a laser generating unit configured to irradiate a laser beam to a bonding member for bonding the light emitting element and the substrate; a temperature sensor configured to measure the temperature of the bonding member; and a control unit configured to control a power and time of a laser beam irradiated to the light emitting element based on data received from the temperature sensor.