Thermosetting Adhesive Slope Control for Electronic Device Bonding

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Solution Overview

Problem

Conventional methods for bonding substrates in electronic devices with piezoelectric elements result in insufficient bonding reliability and hinder the miniaturization of devices due to the formation of slopes in photosensitive adhesive agents, which impede close proximity to structural features.

Innovation Solution

A manufacturing method that applies thermosetting adhesive agents to substrates in a way that minimizes the slope distance from the adhesive to the structural features, allowing for closer proximity and higher density arrangement, thereby enhancing bonding reliability and enabling smaller device sizes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If photosensitive adhesive agent is applied to cover the structure on substrate, then bonding area is increased, but slope formation reduces bonding reliability

Engineering Contradiction:

Improvebonding reliabilityVSAvoidadhesive agent slope

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention changes the physical state of the adhesive agent from photosensitive to thermosetting, and modifies the application method by controlling the thickness parameter. By applying the adhesive agent in a thin layer that does not cover the entire structure, the slope formation is prevented while maintaining sufficient bonding area. The thermosetting process then cures the adhesive to achieve strong bonding.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of applying adhesive agent to completely cover the structure (excessive action), the invention applies it only to the necessary bonding regions (partial action). The adhesive agent is applied to the substrate surface but stops before covering the protruding structure, thereby eliminating slope formation at the edges while providing adequate bonding coverage in the critical areas.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If adhesive agent is patterned to remove slope, then bonding reliability is improved, but device size increases

Engineering Contradiction:

Improvebonding reliabilityVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The invention applies adhesive agent only to the necessary extent - covering the substrate surface up to the base of the structure without over-extending. This partial application eliminates the need for subsequent patterning to remove excess adhesive, thereby maintaining compact device dimensions while ensuring reliable bonding in the critical regions.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The adhesive agent is applied in a controlled thin layer from the beginning, preventing slope formation before it occurs. This preliminary controlled application eliminates the need for later corrective patterning steps, thereby maintaining smaller device size while achieving the desired bonding reliability.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If adhesive agent is located distant from structure, then slope is eliminated, but bonding area is reduced

Engineering Contradiction:

Improveslope eliminationVSAvoidbonding area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The invention changes the application parameter from thick coverage to thin layer application. By controlling the adhesive agent thickness to be thin, it can extend closer to the structure base without forming a slope, thereby maximizing the bonding area while eliminating the harmful slope effect.

Inventive Principle:

Principle #35Parameter changes

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 approach improves bonding reliability and allows for the production of smaller, more reliable electronic devices with increased chip density from silicon monocrystalline substrates, reducing costs and enhancing yield.

Implementation Method 1

bonding the first substrate and the second substrate together, with the structure and the adhesive agent interposed between the first and second substrates

Methodology Applied

Scientific EffectThermosetting:

Implementation Method 2

a piezoelectric element (a kind of drive element) that generates pressure fluctuation in the liquid in the pressure chamber

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS9889629B2Electronic device manufacturing method and electronic device

Publication Date: 2018.02.13 SEIKO EPSON CORP

AI summary

An electronic device is manufactured by a method including applying a photosensitive adhesive agent either to a pressure chamber forming substrate and a vibrating plate or to a sealing plate having a structure of a lower height from a bonding surface, precuring the photosensitive adhesive agent by heating, patterning the precured photosensitive adhesive agent, and bonding the substrates together with the structure (bump electrode) and the photosensitive adhesive agent interposed therebetween.