Semiconductor Unit Wiring Layout to Eliminate Folded Substrate Springback
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Solution Overview
Problem
Flexible display devices experience connection failures due to spring back stress in folded wiring substrates, leading to detachment, breaking, or short circuits, particularly because the thin device substrates and large curvature of wiring substrates increase the likelihood of these issues.
Innovation Solution
A semiconductor unit is designed with a first wiring substrate on the front surface and a second wiring substrate on the back surface of the device substrate, allowing signal transmission without folding, thereby preventing connection failures by eliminating spring back stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a flexible wiring substrate is folded along the outer shape of the device substrate to reduce thickness and frame width, then the display can be contained in a housing and achieve flexible form factor, but spring back stress occurs causing connection failure such as detachment of bonding and breaking or short circuit of wirings
Solution Approach 1:
The wiring substrate is divided into a folded portion (first wiring substrate) and an unfolded portion (second wiring substrate). The folded portion is bent along the outer shape of the device substrate to achieve flexible form factor, while the unfolded portion remains flat to provide stable electrical connection to external circuits, thus avoiding spring back stress at the connection interface.
Solution Approach 2:
The folded wiring substrate acts as an intermediary between the device substrate and the unfolded wiring substrate. It transmits electrical signals from the device substrate to the unfolded portion while absorbing mechanical stress through its folded structure, preventing stress transmission to the bonding interface.
2Adaptability or versatility
If the device substrate is made thin to enable flexible display, then flexibility is improved, but spring back is increased and connection failure is more likely to occur
Solution Approach 1:
The wiring substrate is segmented into folded and unfolded portions. The unfolded portion provides a stable, flat connection interface that is insensitive to the thinness of the device substrate, while the folded portion accommodates the flexibility requirements.
Solution Approach 2:
The wiring substrate extends beyond the plane of the device substrate into a third dimension through folding. This dimensional change allows the connection interface to remain flat and stable even when the device substrate is thin and flexible.
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 enhances the reliability of the semiconductor unit by preventing connection failures and ensuring stable signal transmission between the functional devices and external circuits, even in flexible displays subjected to external forces.
Implementation Method 1
in the folded wiring substrate, stress to return back the folding, that is, spring back occurs
Data Source
AI summary
There are provided a semiconductor unit that prevents connection failure caused by a wiring substrate to improve reliability, a method of manufacturing the semiconductor unit, and an electronic apparatus including the semiconductor unit. The semiconductor unit includes: a device substrate including a functional device and an electrode; a first wiring substrate electrically connected to the functional device through the electrode; and a second wiring substrate electrically connected to the functional device through the first wiring substrate.