Circuit Substrate Flattening Layer for Bubble-Free Display Reliability
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Solution Overview
Problem
Traditional circuit substrate structures face issues with uneven surfaces and bubble formation due to the liquid sealant not uniformly infiltrating, leading to reliability concerns in display devices.
Innovation Solution
A circuit substrate structure incorporating a flattening material layer that covers the flexible printed circuit board and has openings surrounding the integrated circuit chip, eliminating the need for a sealant and preventing bubble formation by ensuring a flat surface through direct coverage by the passivation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid sealant is used to fill the space between passivation layer and pixel array layer, then the sealing function is achieved, but the surface becomes uneven and bubbles are formed
Solution Approach 1:
The patent removes the liquid sealant from the structure entirely. Instead of using sealant to fill the space between the passivation layer and pixel array layer, the invention creates a sealed cavity structure where the sealant is eliminated, thus avoiding surface unevenness and bubble formation while maintaining the sealing function through the structural design of the protrusion and recess portions.
Solution Approach 2:
The pixel array layer is divided into multiple regions with protrusion portions that create segmented recess spaces. This segmentation allows the cavity to be filled with gas or vacuum instead of liquid sealant, achieving both sealing and surface flatness requirements through the distributed structural design.
2Reliability
If liquid sealant is infiltrated into the space between passivation layer and pixel array layer, then sealing is achieved, but bubbles are generated due to blind angles
Solution Approach 1:
The patent extracts and removes the liquid sealant from the sealing process. The sealing function is achieved through the structural design of protrusion and recess portions that create a sealed cavity, eliminating the source of bubble generation associated with liquid sealant infiltration and curing.
Solution Approach 2:
The patent changes the physical state parameter of the sealing medium from liquid (sealant) to gas or vacuum. This parameter change eliminates the harmful effects of liquid sealant such as bubbles and surface unevenness, while the sealing function is maintained through the mechanical structure of the cavity.
3Reliability
If heat curing is applied to the sealant, then the sealant is cured, but bubbles are expanded and lift off the passivation layer
Solution Approach 1:
The patent removes the sealant from the structure, thereby eliminating the need for heat curing. The sealing function is achieved through the structural design of the protrusion and recess portions, which create a mechanically stable sealed cavity without requiring chemical curing that would expand bubbles and reduce adhesion.
Solution Approach 2:
The patent prevents the bubble expansion problem beforehand by eliminating the liquid sealant that would otherwise expand during curing. The structural design of the sealed cavity provides inherent stability without requiring subsequent heat treatment that could cause damage.
Data Source
AI summary
The invention provides a circuit substrate structure and a method for manufacturing thereof. The circuit substrate structure includes a substrate, a pixel array layer, a display unit, a peripheral circuit layer, at least one integrated circuit chip, a flexible printed circuit board, at least one flattening material layer and a passivation layer. In the circuit substrate structure, the flattening material layer is positioned on the peripheral circuit layer, and possesses at least one opening corresponded to and around the integrated circuit chip. By positioning the flattening material layer, the circuit substrate structure possesses a flat surface, and prevents producing air bubbles, so as to enhance the reliability of the display device.