Copper Paste Connection Pattern for Void-Free Member Joining

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Solution Overview

Problem

Conventional member connection methods using copper sintered compacts often result in voids within the sintered compact or between the compact and the connected members due to air penetration, which leads to structural defects and reduced connectivity.

Innovation Solution

A member connection method involving a print pattern with both coating film-formed and non-formed regions, where the non-formed regions act as air release portions, ensuring uniform application of the copper paste and minimizing voids by expanding during lamination and sintering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coating film is formed in the entire connection region, then the connection coverage is improved, but air penetration increases causing voids in the sintered compact

Engineering Contradiction:

ImproveconnectivityVSAvoidair penetration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The connection region is divided into multiple coating film-formed regions separated by coating film non-formed regions. This segmentation allows air to escape through the non-formed regions during lamination while maintaining adequate copper paste coverage in the formed regions for reliable electrical connection after sintering.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Coating film non-formed regions are intentionally created to extract air from the connection region during the lamination process. These regions act as air release channels, removing the harmful air that would otherwise become voids in the sintered compact, while the coating film-formed regions maintain the necessary electrical connectivity.

Inventive Principle:

Principle #2Taking out (Extraction)

2Area of stationary object

If the coating film area is increased to cover the entire connection region, then connection coverage is improved, but void formation increases due to air entrapment

Engineering Contradiction:

Improvecoating film areaVSAvoidvoid suppression

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The coating film area is segmented into multiple discrete coating film-formed regions rather than a continuous full-coverage film. This segmentation reduces the total air-trapping volume while maintaining sufficient copper paste coverage in each region for reliable post-sintering connectivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coating film non-formed regions, which reduce overall coating coverage, are strategically positioned to convert the harmful effect of air entrapment into a beneficial air release mechanism. During lamination, air escapes through these non-formed regions, preventing void formation in the final sintered product while the formed regions ensure adequate electrical connection.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If surface unevenness is present on connecting surfaces, then manufacturing variability increases, but air penetration between coating film and members worsens void formation

Engineering Contradiction:

Improvesurface toleranceVSAvoidair penetration at interface

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

Coating film non-formed regions are created to extract air that penetrates between the coating film and members due to surface unevenness. These regions serve as air release channels, allowing air to escape laterally rather than being trapped at the interface, thereby reducing void formation even when surface tolerance is loose.

Inventive Principle:

Principle #2Taking out (Extraction)

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 suppresses voids within the copper sintered compact and between the compact and the members, enhancing connectivity and reliability of the connection.

Implementation Method 1

the coating film non-formed region functions as a release portion that releases air out of the connection region

Methodology Applied

Scientific EffectAir release:

Implementation Method 2

a sintering step of sintering the coating film to form the copper sintered compact and connecting the first member and the second member by means of this copper sintered compact

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS11887960B2Member connection method

Publication Date: 2024.01.30 RESONAC CORP

AI summary

This member connection method includes a printing step. In the printing step, a coating film-formed region in which the coating film is formed, and a coating film non-formed region in which the coating film is not formed are formed in the print pattern, and the coating film-formed region is divided into a plurality of concentric regions and a plurality of radial regions by means of a plurality of line-shaped regions provided so as to connect various points, which are separated apart from one another in the marginal part of the connection region.