Obviousness — US Patent 11081503

US Patent 11081503 concerns an array substrate and method for mounting an integrated circuit (IC) that addresses misalignment issues, particularly in flexible display devices, by employing inclined and symmetrically arranged pads and corresponding bumps. An analysis of obviousness under 35 U.S.C. § 103 considers whether the claimed invention would have been obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention, based on combinations of prior art references.

Independent Claim 1 Analysis:

Claim 1 of US11081503 describes an electronic device comprising:

An array substrate, a pad portion on the array substrate, and an integrated circuit with a bump portion on the pad portion.
The pad portion includes a first sub-pad unit with an inclined first pad and a second sub-pad unit with an inclined second pad, where these pads are inclined symmetrically in different directions about an imaginary line dividing the pad portion.
The bump portion includes a first sub-bump unit with an inclined first bump and a second sub-bump unit with an inclined second bump, similarly inclined symmetrically in different directions about the same imaginary line.
The pad and bump portions are electrically connected.

The core innovative aspects of Claim 1 reside in the inclined, symmetrically arranged pads on the array substrate and the corresponding inclined, symmetrically arranged bumps on the integrated circuit, specifically designed to mitigate misalignment.

Prior Art Combination and Obviousness Rationale for Claim 1:

A combination of CN104123902A and KR20130053280A would render Claim 1 obvious to a PHOSITA.

CN104123902A (priority date: 2013-04-29) discloses a display panel featuring a substrate and at least one first connecting terminal group and at least one second connecting terminal group. [cite: CN104123902A Abstract] Each connecting terminal (pad) in these groups has a parallelogram shape, and the first and second connecting terminal groups are bilaterally symmetrical by taking a reference line as a symmetrical axis. [cite: CN104123902A Abstract] This reference directly teaches the key structural elements of Claim 1 related to the pad portion: an array substrate with a pad portion comprising first and second sub-pad units having inclined (parallelogram-shaped) pads that are symmetrically arranged in different directions about an imaginary line.
KR20130053280A (priority date: 2011-11-15) describes a "chip on glass type flexible organic light emitting diodes" and explicitly identifies the technical problem of "alignment deviation of a driver IC, which may be caused by the deformation of a flexible substrate." [cite: KR20130053280A Abstract] This reference provides the clear motivation for a PHOSITA to find solutions for mitigating IC-to-substrate misalignment in flexible display applications.

Motivation for Combination and Rationale:
A PHOSITA, aware of the persistent problem of misalignment in flexible display devices due to substrate deformation (as highlighted by KR20130053280A), would be motivated to seek known solutions that offer increased tolerance to such positional shifts. [cite: KR20130053280A Abstract] CN104123902A provides a suitable solution with its teaching of parallelogram-shaped pads arranged symmetrically, a configuration inherently capable of accommodating planar movement or offset while maintaining electrical contact. [cite: CN104123902A Abstract]

It would be an obvious design choice for a PHOSITA to adapt the pad structure from CN104123902A for use in the flexible display context described by KR20130053280A. Furthermore, to ensure optimal and reliable electrical connection between these parallelogram pads and the integrated circuit, it would be a matter of routine engineering for the PHOSITA to design the corresponding bumps on the integrated circuit to also have a parallelogram shape, inclined and symmetrically arranged to match the pads. This mutual design ensures proper mating and leverages the alignment-tolerant properties of the inclined geometry. The resulting structure, where both pads and bumps are inclined and symmetrically arranged, would be readily understood by a PHOSITA to facilitate alignment by allowing translational adjustment along one axis to compensate for misalignment along another, which is the functional benefit described in US11081503.

Obviousness of Dependent Claims:

Claim 2 (parallelogram shape for pads): Directly taught by CN104123902A. [cite: CN104123902A Abstract]
Claims 3 and 4 (matching inclination angles and shapes of bumps to pads): These are obvious design choices for a PHOSITA when designing an IC with bumps to connect to correspondingly shaped pads, ensuring proper electrical and mechanical mating.
Claim 5 (electrical connection between pads and bumps): This is a fundamental aspect of IC mounting and connection, inherent in the disclosures of both CN104123902A and KR20130053280A.
Claim 6 (pad area greater than bump area): US20030160929A1 (priority date: 2002-02-28) explicitly teaches that a "length in a direction parallel to an arrangement direction of the bumps is set to be longer than a length of the bumps" for connection terminals. [cite: US20030160929A1 Abstract] This concept of oversized pads to improve connection tolerance is a well-known technique that a PHOSITA would routinely incorporate into the pad designs of CN104123902A when addressing the misalignment problem in flexible displays (KR20130053280A).
Claim 7 (bump regions overlapping/not overlapping pad regions): This feature describes the functional outcome of the inclined pads/bumps, designed to tolerate misalignment where some parts of the bump might not overlap the pad. This is an inherent result and intended benefit of the combined structure and the problem it solves.
Claim 8 (quadrangle shape for pads): A parallelogram is a type of quadrangle, so this is inherently disclosed by CN104123902A.
Claims 9 and 10 (central rectangular sub-pad/sub-bump units): While CN104123902A focuses on inclined pads, it does not preclude the inclusion of other pad shapes. In the context of array substrates for displays (KR20130053280A), a PHOSITA would recognize that different regions of the substrate might experience varying degrees of deformation or necessitate different connection characteristics. It would be an obvious design optimization to combine the alignment-tolerant inclined pads (from CN104123902A) for peripheral regions susceptible to greater deformation with simpler, potentially more stable, rectangular pads for central regions that may experience less deformation or where manufacturing simplicity is desired. Consequently, designing a matching rectangular central sub-bump unit (Claim 10) for the IC would be a routine design choice to correspond with the rectangular central sub-pad unit (Claim 9).