Display Stack Warping Reduction via Flexible LOCA and Thermal Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronic display stacks experience warping due to differences in thermal expansion coefficients of substrates, leading to stress and potential damage, which affects user experience and device reliability.
Innovation Solution
A liquid optically clear adhesive (LOCA) with a modulus of elasticity below a threshold is used to couple substrates, combined with an external force and controlled heating/cooling to minimize warping by providing a flexible layer that reduces stress and stabilizes adhesive bonds across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid adhesives are used to couple substrates, then bonding strength is improved, but substrate warping increases due to thermal expansion differences
Solution Approach 1:
The patent changes the mechanical parameter of the adhesive by using a two-part adhesive system where Part A has a lower modulus of elasticity (more flexible) and Part B has a higher modulus of elasticity (stiffer). By controlling the ratio of Part A to Part B, the adhesive achieves optimal balance between flexibility to accommodate thermal expansion differences and bonding strength to hold substrates together, thereby reducing substrate warping while maintaining strong bonds.
2Reliability
If high bonding strength is achieved through rigid adhesive, then adhesive bond stability is improved, but stress accumulation increases leading to potential damage
Solution Approach 1:
The patent modifies the adhesive's mechanical properties by adjusting the ratio of two adhesive parts with different modulus of elasticity values. This parameter change allows the adhesive to provide sufficient bonding strength for stability while simultaneously reducing stress accumulation by accommodating thermal expansion differences between substrates, preventing potential damage.
Solution Approach 2:
The patent uses a composite adhesive system consisting of two distinct adhesive parts mixed together. Part A provides flexibility with lower modulus of elasticity to reduce stress, while Part B provides bonding strength with higher modulus of elasticity. The combination creates a composite adhesive material that achieves both reliable bonding and stress reduction, preventing substrate damage.
3Ease of manufacture
If uniform adhesive properties are used, then manufacturing simplicity is improved, but adaptability to thermal expansion differences deteriorates
Solution Approach 1:
The patent employs a composite adhesive material made by mixing two adhesive parts with different mechanical properties. This composite approach maintains ease of manufacture through a simple two-part mixing process while achieving adaptability to thermal expansion differences, as the flexible component (Part A) accommodates expansion/contraction cycles without compromising bond integrity.
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 effectively minimizes substrate warping and associated damage, enhancing the reliability and user experience of electronic devices by maintaining the display stack's integrity under temperature fluctuations.
Implementation Method 1
differences in thermal expansion coefficients of substrates
Implementation Method 2
modulus of elasticity below a threshold is used to couple substrates
Implementation Method 3
controlled heating/cooling to minimize warping
Data Source
AI summary
In some implementations, an electronic device includes a display stack to display content. The display stack can include a number of substrates coupled using a liquid optically clear adhesive (LOCA). In some implementations, the LOCA can have a modulus of elasticity of no greater than 80,000 Pa. Additionally, the display stack can be formed using a process that includes applying an external force to the display stack by placing the display stack between two fixtures. In an implementation, the external force can be applied while heating the display stack at a temperature of at least 60° C. and cooling the display stack according to a particular cooling rate.