Through-Substrate Interconnects for MEMS Driving Uniformity

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Solution Overview

Problem

The existing MEMS devices, such as inkjet heads, face irregularities in driving characteristics due to high electrical resistance in the through-substrate interconnects, which affects the uniformity of driving signals to the piezoelectric elements.

Innovation Solution

The design incorporates a configuration with a first substrate, a second substrate, driven elements, a drive circuit, and interconnects where the through-substrate interconnection part has a lower electrical resistance than the bump parts, ensuring efficient signal transmission by using a larger cross-sectional area for the through-substrate interconnects and optimizing the connection bumps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If through-substrate interconnects with small cross-sectional area are used, then device structure is simplified, but electrical resistance increases causing irregularities in driving characteristics

Engineering Contradiction:

Improvestructure complexityVSAvoiddriving characteristics uniformity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The electrical connection path is segmented into multiple parallel through-substrate interconnects, each contributing to the total conductance. By dividing the current path into multiple segments (interconnects), the overall resistance is reduced while maintaining structural simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple through-substrate interconnects are merged in parallel to form a composite electrical path with lower resistance. The combined effect of multiple interconnects achieves the desired low resistance while keeping individual interconnect dimensions manageable.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If through-substrate interconnects with small cross-sectional area are used, then manufacturing process is simplified, but electrical resistance becomes high affecting signal transmission

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidelectrical resistance

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The electrical connection is segmented into multiple parallel through-substrate interconnects, reducing the cross-sectional area requirement for each individual interconnect while achieving low total resistance through parallel conduction paths.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrical resistance parameter is optimized by changing the number and arrangement of through-substrate interconnects. By adjusting these parameters, low resistance is achieved without requiring large cross-sectional areas that would complicate manufacturing.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If larger cross-sectional area is used for through-substrate interconnects, then electrical resistance decreases improving driving characteristics, but device dimensions increase

Engineering Contradiction:

Improvedriving characteristics uniformityVSAvoidsubstrate area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The electrical connection path is divided into multiple parallel through-substrate interconnects distributed across the substrate. This segmentation allows achieving low total resistance through parallel conduction without requiring any single interconnect to have a large cross-sectional area.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of increasing the cross-sectional area (two-dimensional approach) of individual interconnects, the solution transitions to a multi-interconnect parallel arrangement (utilizing the number dimension), achieving low resistance without increasing substrate area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11430755B2Electronic device including first substrate having first and second surfaces opposite from each other, second substrate facing first surface, and drive circuit facing second surface

Publication Date: 2022.08.30 BROTHER KOGYO KK

AI summary

An electronic device includes: a first substrate having a first surface and a second surface opposite from the first surface; a second substrate facing the first surface; driven elements provided at the second substrate; a drive circuit facing the second surface; a first interconnect provided at the first surface; a second interconnect provided at the second surface; a through-substrate interconnection part penetrating the first substrate in a thickness direction thereof; a first bump part; and a second bump part. The drive circuit is capable of outputting drive signals for driving the driven elements. The through-substrate interconnection part electrically connects the first interconnect and the second interconnect. The first bump part electrically connects the first interconnect and the driven elements. The second bump part electrically connects the second interconnect and the drive circuit. The through-substrate interconnection part has an electrical resistance lower than an electrical resistance of the second bump part.