Chip Electrode Paste Coating Uniformity

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Solution Overview

Problem

The existing method for manufacturing chip-like electronic components results in uneven thickness of electrically conductive paste on ridge portions, leading to reduced reliability and increased risk of solder leach, plating penetration, and tombstone phenomenon during surface mounting.

Innovation Solution

A method involving the application of an electrically conductive paste and a sheet to the chip element such that the sheet overlaps the ridge portions, ensuring the paste covers them, which is then dried and sintered to form external electrodes with increased thickness and flat surfaces, preventing adhesive strength reduction and tombstone phenomenon.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the end surface is dipped into electrically conductive paste by gravity, then the paste is applied to the chip element, but the thickness of paste on ridge portions becomes less than on end surface

Engineering Contradiction:

Improvepaste applicationVSAvoidpaste thickness uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by coating the electrically conductive paste onto the ridge portions before dipping the end surface into the paste. This pre-coating ensures that the ridge portions have sufficient paste thickness before the dipping process, preventing the paste from being depleted at the ridges during immersion. The end surface is then dipped into the paste to complete the coating, ensuring uniform and sufficient paste coverage on all surfaces including the ridges.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If paste thickness on ridge portions is small, then the application process is simpler, but adhesive strength decreases and solder leach occurs

Engineering Contradiction:

Improveapplication processVSAvoidadhesive strength

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-coating the ridge portions with electrically conductive paste before the end surface dipping process. This ensures that the ridge portions have sufficient paste thickness from the beginning, maintaining high adhesive strength and preventing solder leach during subsequent processing, while keeping the overall application process simple and efficient.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If paste thickness on ridge portions is small, then the coating process is faster, but plating liquid penetrates into chip element

Engineering Contradiction:

Improvecoating speedVSAvoidplating liquid penetration

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-coating the ridge portions with electrically conductive paste before the end surface dipping process. This creates a sufficient paste barrier on the ridge portions that prevents plating liquid from penetrating into the chip element during subsequent plating operations, while maintaining efficient coating speed through the streamlined two-step process.

Inventive Principle:

Principle #10Preliminary action

4Ease of manufacture

If end surface assumes convex curved shape, then paste is applied by gravity, but R of corner portions increases causing tombstone phenomenon

Engineering Contradiction:

Improvepaste application methodVSAvoidcorner curvature radius

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

The patent applies preliminary action by pre-coating the ridge portions with electrically conductive paste before dipping the end surface. This ensures that the paste is properly distributed on the ridges first, preventing the formation of convex curved shapes at the corners during the dipping process. As a result, the corner portions maintain appropriate curvature radius that prevents tombstone phenomenon during reflow soldering, while still using the simple gravity-based dipping method.

Inventive Principle:

Principle #10Preliminary action

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 method enhances the reliability of electronic components by ensuring uniform thickness and flat surfaces on external electrodes, reducing solder leach and tombstone defects during mounting.

Implementation Method 1

a drying step of drying the electrically conductive paste and the sheet to form a layer including the electrically conductive material

Methodology Applied

Scientific EffectDrying:

Implementation Method 2

a formation step of sintering the layer and forming the external electrodes

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS8291585B2Method for manufacturing electronic component

Publication Date: 2012.10.23 TDK CORP

AI summary

A chip element in the form of a substantially rectangular parallelepiped having end surfaces and side surfaces is formed (step of forming chip element). An electrically conductive green sheet is formed (step of forming electrically conductive green sheet). An electrically conductive paste is applied to the end surfaces of the chip element (step of application electrically conductive paste). A chip element is formed in which the electrically conductive green sheet is attached to the end surface via the electrically conductive paste applied to the end surface of the chip element (step of attaching electrically conductive sheet). In the step of attaching, the end surface of the electrically conductive green sheet on the side of the side surfaces is positioned on the outside of the side surfaces, and the electrically conductive paste applied to the end surface is pressed out into a space between the electrically conductive green sheet and ridge portions.