Display Pad Bonding With Lattice Conductive Balls
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Solution Overview
Problem
In display devices, the narrow spacing of pad electrodes and the irregular arrangement of conductive balls in anisotropic conductive films lead to uneven density and potential short-circuiting, making it difficult to maintain electrical connections between pad electrodes and bump electrodes.
Innovation Solution
A conductive film member with conductive balls arranged in a lattice shape and a film package with different thickness areas, where the conductive balls in one area are exposed and in another area are covered, allowing for uniform density and preventing short-circuiting, along with a method involving a non-cured resin layer and pressure application to ensure proper contact and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively thick anisotropic conductive film with irregularly arranged conductive balls is used, then the film can cover the pad electrodes and provide electrical connection, but the density of conductive balls becomes uneven and adjacent electrodes may short-circuit
Solution Approach 1:
The patent applies local quality by having different film thicknesses in different regions: a first thickness in the first area (overlapping pad electrodes) and a second thickness in the second area (not overlapping pad electrodes). This localized differentiation ensures uniform conductive ball density where needed while preventing short-circuits in non-overlapping regions.
Solution Approach 2:
The patent changes the thickness parameter of the anisotropic conductive film across different regions. By controlling the film thickness to be smaller in areas overlapping pad electrodes and larger in areas not overlapping them, the patent achieves uniform conductive ball distribution and prevents short-circuiting while maintaining reliable electrical connections.
2Strength
If the resin layer thickness is increased to ensure coverage, then adhesion improves, but conductive ball density becomes uneven during curing
Solution Approach 1:
The patent implements local quality by varying the resin layer thickness locally: thinner in regions overlapping pad electrodes to maintain uniform conductive ball density, and thicker in regions not overlapping pad electrodes to ensure adequate coverage and adhesion. This localized thickness control resolves the contradiction between adhesion strength and uniformity.
3Reliability
If pressure is applied during curing to improve contact, then electrical connection reliability improves, but conductive balls may overlap and cause short-circuits
Solution Approach 1:
The patent applies local quality by creating regions with different film thicknesses: thinner regions over pad electrodes that accommodate pressure application without causing conductive ball overlap, and thicker regions in non-overlapping areas that provide buffer space. This localized structure allows pressure to be applied for reliable contact while preventing short-circuits.
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 configuration ensures uniform density of conductive balls and prevents short-circuiting between pad and bump electrodes, facilitating reliable electrical connections and increased adhesive strength between the film package and conductive film member.
Implementation Method 1
when the flexible printed circuit board applies a pressure to the anisotropic conductive film in the depth direction, a relatively large amount of the resin layer may be reflowed
Implementation Method 2
A conductive film member including conductive balls disposed on the pad electrodes
Implementation Method 3
an adhesive layer disposed between the film package and the conductive film member
Data Source
AI summary
A method of manufacturing a display device including the steps of providing a lower substrate having a display area and a pad area, forming a display structure in the display area of the lower substrate, forming pad electrodes in the pad area of the lower substrate to be spaced apart from each other in a first direction parallel to a top surface of the lower substrate, forming an upper substrate on the display structure to face the lower substrate in the display area, forming a conductive film member including a non-cured resin layer and conductive balls arranged in a lattice shape on the pad electrodes, the non-cured resin layer overlapping the pad electrodes, and forming a film package on the non-cured resin layer, the film package including bump electrodes overlapping the pad electrodes.