Photosensitive Adhesive Layering for Substrate Bonding
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Solution Overview
Problem
The existing bonding methods using photosensitive adhesives in electronic devices, such as liquid ejecting apparatuses, face challenges in achieving strong adhesion between substrates, especially when the substrate surfaces are rough, leading to decreased bonding strength due to the adhesive's patterning and curing processes.
Innovation Solution
A manufacturing method involving multiple layers of photosensitive adhesives with varying degrees of cure is employed, where a second photosensitive adhesive with a lower degree of cure is used to enhance bonding strength by overlapping and curing between substrates, and optionally a third adhesive with a higher degree of cure is used to further ensure adhesion, expanding beyond the first adhesive's boundaries for increased contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photosensitive adhesive is cured to a certain degree to prevent shape collapse, then patterning accuracy is improved, but bonding strength between substrates decreases
Solution Approach 1:
The adhesive layer is divided into multiple layers with different cure degrees. The first adhesive layer is cured to a higher degree to maintain shape and prevent collapse, while the second adhesive layer is cured to a lower degree to provide flexibility and strong bonding. This segmentation allows each layer to fulfill its specific function without compromising the other.
Solution Approach 2:
Different regions of the adhesive structure are given different cure degrees according to their functional requirements. The first adhesive layer (closer to the substrate) has a higher degree of cure for shape stability, while the second adhesive layer (outer layer) has a lower degree of cure for enhanced bonding and flexibility. This local differentiation resolves the contradiction between shape maintenance and bonding strength.
2Ease of manufacture
If the substrate surface is rough, then manufacturing ease is improved, but adhesion by the adhesive decreases remarkably
Solution Approach 1:
The invention uses a composite adhesive structure consisting of two adhesive layers with different properties. The first layer provides shape stability and can adhere to rough surfaces, while the second layer provides enhanced bonding strength and flexibility. This composite approach allows the system to overcome the adverse effects of surface roughness that would normally reduce adhesion.
Solution Approach 2:
The first adhesive layer, cured to a higher degree, acts as a cushioning layer that compensates for surface irregularities. By establishing a stable, shape-retaining base layer first, the system creates a foundation that mitigates the negative impact of rough substrate surfaces on overall adhesion performance.
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 method effectively increases the bonding strength between substrates while maintaining patterning accuracy and preventing adhesive collapse, even on rough surfaces, by utilizing the second adhesive's lower cure state to ensure adhesion and the third adhesive's higher cure state for additional bonding reliability.
Implementation Method 1
an adhesive (photosensitive adhesive) configured by a resin or the like with photosensitivity is used for the above adhesive. If such an adhesive is used, one substrate is first coated with an adhesive of liquid type by using a spin coater or the like, and the adhesive is cured to a certain degree by heating. Then, by performing exposure and development, the adhesive is patterned in a predetermined position.
Implementation Method 2
the adhesive is cured to a certain degree by heating. Thereafter, by attaching the other substrate so as to face the one substrate, curing the adhesive by heating again, and thereby both the substrates are bonded together.
Data Source
AI summary
A manufacturing method of an electronic device includes a first stacking process of forming a first photosensitive adhesive on a surface on a second substrate side in a first substrate; and a second stacking process of forming a second photosensitive adhesive, which overlaps the first photosensitive adhesive, having a lower degree of cure than that of the first photosensitive adhesive; and a bonding process of bonding together the first substrate and the second substrate by curing the second photosensitive adhesive by heating, in a state in which the first photosensitive adhesive and the second photosensitive adhesive are interposed between the first substrate and the second substrate.