Display Device Output Pads with Varying Heights
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Solution Overview
Problem
Conventional display devices face image quality deterioration due to contact failures between output and input pads and bumps, caused by the flow phenomenon of protective films and adhesive layers with low Young's modulus, especially when heated, leading to misalignment and increased distances between pads and bumps in output areas.
Innovation Solution
The display device incorporates a substrate with distinct output pads of varying heights, conductive films with differently sized conductive balls, and a specific arrangement of output bumps to maintain contact integrity, even under thermal stress, ensuring the first output pads have a larger height and the second output pads a smaller height, with conductive balls connecting bumps to pads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If protective films and adhesive layers with low Young's modulus are used to protect the substrate bottom surface, then substrate protection is improved, but contact failures occur between pads and bumps due to flow phenomenon under thermal stress
Solution Approach 1:
The patent applies different heights to different output pads (first output pads with greater height than second output pads) to locally adapt to the flow phenomenon in different areas. This local quality differentiation ensures that each pad maintains proper contact with its corresponding bump despite the overall substrate deformation caused by the protective films and adhesive layers flowing under thermal stress.
Solution Approach 2:
The patent changes the height parameter of output pads based on their location and the expected flow magnitude. By varying the pad height parameter, the invention compensates for the displacement caused by the flow phenomenon, maintaining reliable electrical contact between pads and bumps even when the protective films and adhesive layers deform under heating conditions.
2Productivity
If heating is applied during manufacturing or operation, then manufacturing or display performance is improved, but thermal-induced flow phenomenon causes misalignment between pads and bumps
Solution Approach 1:
The patent implements preliminary action by pre-adjusting the heights of output pads before the heating process occurs. The first output pads are designed with greater heights in advance to compensate for the expected flow phenomenon that will occur during subsequent heating steps in manufacturing or operation, thereby maintaining alignment precision despite thermal effects.
Solution Approach 2:
The patent applies parameter changes by varying the height dimension of output pads based on their position and the anticipated thermal flow. This parameter adjustment is made beforehand to counteract the misalignment that would otherwise occur during heating, ensuring manufacturing precision is maintained even when thermal-induced flow happens.
3Ease of manufacture
If uniform pad heights are used across all output areas, then manufacturing simplicity is improved, but contact failures occur in areas with greater flow phenomenon
Solution Approach 1:
The patent transitions from uniform pad heights to local quality differentiation, where first output pads have greater heights than second output pads. This local adaptation ensures that pads in areas experiencing greater flow phenomenon maintain proper contact, improving reliability while the overall structure remains relatively simple to manufacture.
Solution Approach 2:
The patent introduces height variation as an additional dimensional parameter to solve the contact reliability problem. By varying the height dimension of pads rather than changing their planar position, the invention maintains manufacturing simplicity while achieving reliable contact in areas with different flow characteristics.
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 prevents contact failures between upper output bumps and first output pads, maintaining image quality by ensuring consistent electrical connections despite thermal-induced flow phenomena in the protective films and adhesive layers.
Implementation Method 1
The conductive film may include a film layer, first conductive balls, and second conductive balls... at least one of the first conductive balls may electrically connect at least one of the first output pads to at least one first output bump... and at least one of the second conductive balls may electrically connect at least one of the second output pads to at least one of the second output bumps
Implementation Method 2
the display device may further include a lower protective film and an adhesive layer configured to bond the substrate to the lower protective film
Data Source
AI summary
A display device includes a substrate including a display area and a pad area, a display structure disposed in the display area on the substrate, and a driving integrated circuit disposed in the pad area on the substrate and including a circuit part including an input area, a first output area adjacent to the display area, and a second output area between the input area and the first output area, upper output bumps disposed in the first output area on a bottom surface of the circuit part, and lower output bumps disposed in the second output area on the bottom surface of the circuit part. First output pads are disposed between the substrate and the upper output bumps, and have a first height. Second output pads are disposed between the substrate and the lower output bumps, and have a second height smaller than the first height.