Micro-LED Module Fabrication with Circuit Board Flatness Control
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Solution Overview
Problem
The poor flatness of circuit boards in micro-LED module fabrication makes it difficult to precisely mount micro-LED chips in their correct positions, leading to defects and reliability issues in displays.
Innovation Solution
A method is introduced where micro-LED chips are first bonded to a circuit board with enhanced flatness using solder bumps, and then driver ICs are attached to the opposite surface, utilizing a vacuum chuck to maintain high flatness and ensuring precise chip placement. The method involves forming solder bumps on one surface of the circuit board, bonding micro-LED chips to these bumps, and subsequently bonding driver ICs to the other surface using solders with a lower melting point to prevent re-melting of the solder bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If driver ICs are attached to the circuit board first, then the circuit board can be assembled with electronic components, but the flatness of the circuit board deteriorates making it difficult to precisely mount micro-LED chips
Solution Approach 1:
The patent applies preliminary action by enhancing the flatness of the circuit board before mounting the micro-LED chips. The flatness enhancement process is performed in advance to ensure the board surface is sufficiently flat for precise chip placement, while driver ICs are attached after this preparation step to avoid compromising the enhanced flatness.
Solution Approach 2:
The patent segments the assembly process into distinct stages: first enhancing flatness, then mounting micro-LED chips, and finally attaching driver ICs. This segmentation allows each operation to be optimized independently, preventing the driver IC attachment from affecting the flatness required for precise chip mounting.
2Productivity
If micro-LED chips are mounted on a circuit board with poor flatness, then the assembly process can proceed, but the chips cannot be mounted in correct positions leading to defects
Solution Approach 1:
The patent performs flatness enhancement as a preliminary action before chip mounting, ensuring the circuit board has sufficient flatness to accommodate precise micro-LED chip placement. This pre-preparation eliminates position accuracy issues that would otherwise result from mounting on a warped surface.
3Strength
If solders with high melting point are used to bond driver ICs, then strong bonding is achieved, but the solder bumps bonding micro-LED chips may re-melt causing defects
Solution Approach 1:
The patent applies local quality by using different solder materials with different melting points for different bonding locations. Low melting point solder is used specifically for bonding micro-LED chips to prevent re-melting, while high melting point solder is used for bonding driver ICs to achieve strong bonding. This location-specific material selection resolves the contradiction between bonding strength and reliability.
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 ensures accurate and precise mounting of micro-LED chips, enhancing the reliability and quality of micro-LED modules by maintaining the flatness of the circuit board during the attachment process, thereby reducing defects and improving display performance.
Implementation Method 1
a vacuum chuck formed with through-holes is brought into contact with the other surface of the circuit board and the circuit board is then adsorbed to the vacuum chuck by vacuum suction through the through-holes
Implementation Method 2
heating the solder bumps to bond the micro-LED chips to the one surface of the circuit board through the solder bumps
Implementation Method 3
heating the solders to bond the driver ICs to the other surface of the circuit board through the solders
Data Source
AI summary
Disclosed is a method for fabricating a micro-LED module. The method includes: preparing a circuit board; forming solder bumps on one surface of the circuit board; arranging micro-LED chips on the one surface of the circuit board such that the micro-LED chips are in contact with the solder bumps; heating the solder bumps to bond the micro-LED chips to the one surface of the circuit board through the solder bumps; arranging driver ICs on the other surface of the circuit board such that the driver ICs are in contact with solders on the other surface of the circuit board in a state in which the micro-LED chips are bonded to the circuit board; and heating the solders to bond the driver ICs to the other surface of the circuit board through the solders. The micro-LED chips are arranged on the one surface of the circuit board after the flatness of the circuit board is enhanced.