Display Device Circuit Board Alignment Holes for Pad Bonding
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Solution Overview
Problem
In high-resolution display devices, aligning a large number of input pad electrodes with lead electrodes is challenging, leading to potential screen driving failures due to misalignment and lifting of lead electrodes on the printed circuit board.
Innovation Solution
The display device incorporates alignment marks on the substrate that match corresponding alignment mark holes in the circuit board, ensuring precise alignment and preventing lead electrode lifting by using anisotropic conductive films for electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of input pad electrodes is increased to achieve high resolution, then the display resolution is improved, but the alignment difficulty between pad electrodes and lead electrodes increases
Solution Approach 1:
The patent introduces alignment marks as intermediary elements between the pad electrodes and lead electrodes. These alignment marks serve as reference points that facilitate precise alignment during the bonding process, acting as a mediator that simplifies the alignment task for the numerous electrodes required for high resolution displays.
Solution Approach 2:
The patent creates a simplified copy or representation of the electrode arrangement through alignment marks. Instead of directly aligning numerous electrodes, the alignment marks provide a reduced-complexity template that guides the positioning, making the alignment process more manageable while maintaining the precision needed for high resolution.
2Reliability
If the circuit board is attached to the pad area, then electrical connection is established, but lead electrode lifting occurs causing screen driving failure
Solution Approach 1:
The patent applies preliminary anti-action by designing the alignment marks to protrude beyond the pad electrodes in the thickness direction. This protruding structure creates a mechanical constraint that prevents the lead electrodes from lifting during the bonding process, counteracting the harmful effect before it can occur.
Solution Approach 2:
The alignment marks are prepared in advance with a specific protruding structure that will prevent electrode lifting during subsequent bonding operations. This preliminary structural preparation ensures that when the circuit board is attached, the lead electrodes are already constrained and cannot lift, preventing screen driving failure.
3Manufacturing precision
If alignment marks protrude more than pad electrodes in thickness direction, then alignment tolerance is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by making only specific portions of the structure (the alignment marks) protrude beyond the pad electrodes, rather than increasing the thickness of the entire circuit board or substrate. This localized structural modification achieves the alignment tolerance improvement without globally increasing device 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
This solution reduces alignment tolerance and prevents lead electrode lifting, ensuring reliable electrical connections and preventing screen driving failures.
Implementation Method 1
using anisotropic conductive films for electrical connection
Data Source
AI summary
A display device includes a substrate including a display area including pixels and a non-display area around the display area and including a pad area, and a circuit board attached to the pad area. Pad electrodes arranged along a first direction and a first alignment mark located at a side of the pad electrodes in the first direction and protruding more than the pad electrodes are disposed on the substrate in the pad area. The circuit board includes a base portion, and lead electrodes disposed on the base portion and respectively facing the pad electrodes. A first alignment mark hole is defined through the base portion at a side of the lead electrodes in the first direction, the first alignment mark and the first alignment mark hole have a same shape as each other, and the first alignment mark is accommodated in the first alignment mark hole.