Circuit Substrate Coating to Prevent Electrode Pad Separation

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Solution Overview

Problem

Existing circuit boards with projecting electrodes on large electrode pads are prone to separation at their outer peripheries due to thermal or drop impacts, especially when the electrode pads are at the corners.

Innovation Solution

The circuit board design includes electrode pads that are larger than the projecting electrodes, with a coating layer covering at least a portion of the outer periphery of the electrode pads, particularly at the corners, to prevent separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the electrode pad area is made large to accommodate projecting electrodes, then the electrical connection area is improved, but the electrode pad becomes prone to separation from the circuit board under thermal or drop impact

Engineering Contradiction:

Improveelectrode pad areaVSAvoidelectrode pad separation resistance

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

A coating layer is applied over the electrode pad to provide a protective shell that prevents separation. This thin film structure reinforces the electrode pad edges and maintains bonding to the circuit board under thermal or mechanical impact while preserving the large electrode pad area for electrical connection.

Inventive Principle:

Principle #30Flexible shells and thin films

2Area of stationary object

If the electrode pad is positioned at the corner of the circuit board, then space utilization is improved, but the electrode pad is most susceptible to impact separation

Engineering Contradiction:

Improvespace utilizationVSAvoidimpact susceptibility

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The coating layer is selectively applied to the electrode pad areas most susceptible to impact, particularly at corner positions. This localized treatment provides enhanced protection where it is most needed while maintaining the overall compact layout and space utilization of the circuit board.

Inventive Principle:

Principle #3Local quality

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 design effectively prevents electrode pad separation from the circuit board under impact by enhancing the structural integrity of the electrode pads, especially at corners, using a coating layer that matches thermal expansion coefficients with the substrate.

Implementation Method 1

using a coating layer that matches thermal expansion coefficients with the substrate

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS12396094B2Circuit substrate and module

Publication Date: 2025.08.19 MURATA MFG CO LTD

AI summary

A circuit board 1 including: a substrate; an electrode pad on a surface of the substrate; and a projecting electrode on the electrode pad, wherein the electrode pad on which the projecting electrode is disposed is larger than the projecting electrode when viewed from above, and a coating layer covers at least a portion of an outer periphery of the electrode pad on which the projecting electrode is disposed.