Micro LED Package Structure for Flat Thin Direct Bonding
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Solution Overview
Problem
The inconsistency in wafer dimensions between semiconductor and light-emitting diode factories leads to dimension mismatch issues, resulting in excessive height differences between IC dies and driving substrates, which complicates exposure processes and increases waste due to the need for wire bonding.
Innovation Solution
A micro light-emitting diode package structure with a containing groove defined by a first and second base layer, where the display unit, including a control circuit board and micro light-emitting diode assembly, is disposed, reducing height differences and eliminating the need for wire bonding by ensuring better flatness and thinner package thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding method is used to connect IC die and driving substrate, then electrical connection is achieved, but package thickness increases and flatness deteriorates
Solution Approach 1:
The patent extracts and eliminates the wire bonding process from the manufacturing flow. By designing the IC die and driving substrate to be directly bonded through aligned contact pads, the intermediate wire bonding step is removed, thereby reducing package thickness and improving flatness while maintaining electrical connection reliability
Solution Approach 2:
The patent employs asymmetric thickness design where the IC die thickness is intentionally made smaller than the driving substrate thickness. This asymmetry, combined with direct bonding, eliminates the need for wire bonding and achieves both thin package profile and good flatness by allowing the thinner die to sit flush on the substrate surface
2Manufacturing precision
If IC die is directly bonded to driving substrate, then exposure flatness is improved, but height difference exceeds 550 μm causing exposure difficulty
Solution Approach 1:
The patent changes the thickness parameter of the IC die, designing it to be smaller than the driving substrate (e.g., die thickness 100-300 μm while substrate is thicker). This parameter change enables direct bonding without excessive height difference, improving exposure flatness while keeping the height difference within acceptable limits for exposure processes
Solution Approach 2:
The patent performs preliminary thickness matching design before the bonding process. By pre-designing the IC die with appropriate thickness and contact pad alignment, the height difference is controlled within 550 μm before bonding occurs, ensuring exposure flatness is achieved without requiring post-bonding correction
3Productivity
If light-emitting diodes are transferred to 8-inch wafer factory equipment in batches, then processing capacity is improved, but dimension inconsistency causes connection failure
Solution Approach 1:
The patent designs the IC die with standardized contact pad dimensions and positioning that are universally compatible with both 4-inch/6-inch LED wafers and 8-inch CMOS wafers. This universal interface design allows direct connection across different wafer size platforms, enabling batch processing on 8-inch equipment while maintaining dimension consistency and connection reliability
Data Source
AI summary
A micro light-emitting diode package structure including a first base layer, a second base layer and a display unit is provided. The second base layer is disposed on the first base layer and has an opening. The opening exposes a part of the first base layer, and the opening and the exposed first base layer define a containing groove. The display unit is disposed in the containing groove, and the display unit includes a control circuit board and a micro light-emitting diode assembly. The micro light-emitting diode assembly is disposed on the control circuit board and electrically connected to the control circuit board.