Micro LED Assembly With Localized Conductive Balls to Prevent Shorts
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Solution Overview
Problem
The challenge in assembling micro LED displays lies in precisely positioning a large number of semiconductor light emitting devices on a wiring board, where conventional methods using conductive balls can lead to electrical disconnection or short circuits, hindering high-resolution display implementation.
Innovation Solution
A method involving localized conductive balls on spaced adhesive layers, with a non-conductive layer covering the adhesive layers, allows direct transfer of light emitting devices from a growth substrate to a thin film transistor substrate, ensuring electrical connectivity and avoiding short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive balls are used to electrically connect light emitting devices to electrodes, then electrical connection is achieved, but adhesive layer flows in peripheral directions causing circuit open
Solution Approach 1:
The patent applies local quality by creating a non-conductive region in the center of the adhesive layer and positioning conductive balls only in peripheral regions. This localized differentiation ensures that conductive balls remain in stable positions for reliable electrical connection while preventing adhesive layer flow from disrupting the connection, thus resolving the contradiction between connection reliability and positioning precision.
Solution Approach 2:
The adhesive layer is segmented into a non-conductive central region and conductive peripheral regions containing conductive balls. This segmentation separates the adhesive function from the conductive function, allowing the adhesive to flow without displacing conductive balls, thereby maintaining both electrical connection reliability and conductive ball positioning precision.
2Reliability
If bonding pressure is applied to connect conductive balls between electrodes, then electrical connection is established, but adhesive layer flows causing conductive balls to move and circuits to open
Solution Approach 1:
By creating a non-conductive central region in the adhesive layer, the patent provides a stable zone that resists flow under bonding pressure. Conductive balls positioned in peripheral regions benefit from this stable environment, preventing displacement during the bonding process while maintaining reliable electrical connections, thus resolving the contradiction between connection reliability and bonding process stability.
3Reliability
If number of conductive balls is increased to improve electrical connection, then connection reliability improves, but short circuit may occur between electrodes
Solution Approach 1:
The patent implements local quality by restricting conductive balls to peripheral regions of the adhesive layer while maintaining a non-conductive central region. This spatial differentiation allows sufficient conductive balls to be used for reliable electrical connection without increasing short circuit risk, as the non-conductive center prevents unintended electrical paths between electrodes.
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 enables reliable, precise, and high-resolution micro LED displays by preventing electrical disconnections and short circuits, enhancing mass productivity and flexibility.
Implementation Method 1
a non-conductive adhesive layer positioned on the conductive adhesive layer
Implementation Method 2
the conductive balls electrically connect the electrode of the light emitting device and the electrode on the thin film transistor substrate
Data Source
AI summary
Discussed is a display device using a light emitting device includes a plurality of anode electrodes, a plurality of cathode electrodes positioned on one side of the anode electrodes, and a plurality of light emitting device assemblies electrically connected to the anode and cathode electrodes to configure individual sub-pixels. The light emitting device assembly includes a light emitting device, a first electrode disposed on the light emitting device and electrically connected to the anode electrode through conductive balls, a second electrode disposed on the light emitting device and electrically connected to the cathode electrode by conductive balls, first adhesive layers disposed on the first electrode and the second electrode to be spaced apart from each other, and a second non-conductive adhesive layer positioned on the first adhesive layers.