Display Panel Pad Layout for Stable Thermo-Compression Bonding
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Solution Overview
Problem
The reliability of electrical connections in electronic devices is compromised due to manufacturing errors, thermal expansion, and differences in resilience between electronic components, leading to delamination and misalignment during the bonding process.
Innovation Solution
An electronic device design incorporating a display panel with a base substrate, insulation layers, panel pads, and a flexible circuit board with output pads and stress relaxation pads, along with an adhesive interconnect layer, to enhance electrical connectivity and stability by managing thermal stress and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermo-compression bonding is used to connect pad portions of electronic components, then electrical connection is achieved, but delamination and misalignment occur due to thermal expansion and resilience differences
Solution Approach 1:
The patent changes the physical state and material properties of the adhesive layer by selecting specific resin systems (epoxy, polyimide, polyester) and adjusting their molecular weight, glass transition temperature, and crosslinking density to match the thermal expansion coefficients of bonded components, thereby maintaining bonding stability under thermal stress
Solution Approach 2:
The patent uses composite adhesive materials combining organic resins with inorganic fillers (silica, alumina) and coupling agents (silane) to create an adhesive layer with tailored thermal expansion properties that bridge the gap between components with different resilience, preventing delamination while maintaining electrical connection reliability
2Reliability
If pad portions are bonded through alignment step, then electrical connection is established, but manufacturing errors cause size deviations from design specifications
Solution Approach 1:
The patent adjusts the viscosity and curing characteristics of the adhesive layer to compensate for pad size variations, allowing the adhesive to flow and conform to slightly misaligned or non-uniform pad surfaces while maintaining reliable electrical connection
Solution Approach 2:
The adhesive layer acts as an intermediary substance between pad portions, absorbing dimensional deviations and alignment errors through its viscoelastic properties, thereby ensuring continuous electrical connection despite manufacturing tolerances in pad size and position
3Ease of manufacture
If electronic components are shrunk or expanded due to heat in bonding process, then bonding is completed, but electrical connection reliability is lowered
Solution Approach 1:
The patent selects adhesive materials with thermal expansion coefficients matched to the average of the bonded components, allowing the adhesive layer to expand and contract harmoniously with the components during thermal cycling, preventing stress concentration and maintaining electrical connection reliability
Solution Approach 2:
The patent designs the adhesive layer with predetermined damping characteristics and shock-absorbing properties to preemptively cushion against thermal expansion and contraction forces that occur during bonding and operation, preventing damage to electrical connections before they can occur
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
The solution improves the reliability of electrical connections by reducing delamination and maintaining stability during thermal expansion, ensuring consistent alignment and efficient electrical communication between components.
Implementation Method 1
Two electronic components are electrically connected through the connection of pads. The pad portions of the two electronic components are bonded through an alignment step, and may be bonded by using a thermo-compression bonding tool and the like.
Implementation Method 2
an adhesive interconnect layer disposed between the display panel and the circuit board and electrically connecting the display panel and the circuit board
Data Source
AI summary
Provided is an electronic device including a display panel including a base substrate, pixels, a first insulation layer, and panel pads spaced along a first direction from pixels and each arranged along a second direction crossing the first direction, a circuit board disposed on the display panel and connected to panel pads, and an adhesive interconnect layer disposed between the display panel and the circuit board and electrically connecting the display panel and the circuit board. The circuit board includes a flexible substrate including a top surface facing the base substrate, output pads disposed on the flexible substrate and connected to panel pads, each obliquely extending in the first and second directions and arranged along the second direction, an alignment pad spaced along the second direction from output pads, and a stress relaxation pad disposed between output pads and alignment pads and electrically insulated from panel pads.