Semiconductor Device NSMD Conductor Aperture Stress Reduction

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Solution Overview

Problem

The reliability of semiconductor devices is compromised due to the breakdown of solder balls connected between the conductor pattern for heat dissipation and the mounting substrate under temperature cyclic loading, primarily due to stress concentration at inflection points caused by the shape defined by the solder resist apertures.

Innovation Solution

The semiconductor device employs a conductor pattern with overlapping apertures and conductor apertures, forming an NSMD structure to prevent inflection points and reduce stress concentration, thereby enhancing the coupling reliability and heat dissipation efficiency by using an NSMD structure that separates the solder ball from the solder resist film, reducing the likelihood of breakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the conductor pattern and terminals are coupled through solder material to improve heat dissipation, then heat dissipation characteristics are improved, but reliability deteriorates due to stress concentration at inflection points

Engineering Contradiction:

Improveheat dissipation characteristicsVSAvoidreliability of semiconductor device

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent extracts the harmful inflection points from the solder ball shape by implementing an NSMD structure where the conductor aperture is positioned such that the solder ball does not contact the solder resist film, eliminating the source of stress concentration while maintaining heat dissipation functionality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potential harm of solder ball deformation into benefit by designing the conductor aperture to control solder ball formation, ensuring that the solder ball maintains a spherical shape without inflection points, thereby improving both reliability and heat dissipation

Inventive Principle:

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

2Ease of manufacture

If apertures are formed in solder resist to expose conductor pattern, then solder coupling is enabled, but inflection points are created causing stress concentration

Engineering Contradiction:

Improvesolder coupling capabilityVSAvoidstress resistance of solder ball

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent applies local quality by creating a specific NSMD structure where the conductor aperture is positioned to expose the conductor pattern while the solder ball formation area is controlled to avoid contact with solder resist film, providing different functional qualities in different regions of the aperture structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional SMD approach by using NSMD structure where the conductor aperture is designed such that the solder ball does not contact the solder resist film, reversing the typical interaction between solder and resist to eliminate inflection points

Inventive Principle:

Principle #13The other way round (Inversion)

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 configuration improves the operational reliability and heat dissipation characteristics by minimizing solder ball breakage and maintaining electrical integrity under temperature fluctuations, ensuring stable performance and extended device lifespan.

Implementation Method 1

conductor pattern for heat dissipation and terminals of a mounting substrate are coupled together through a conductive coupling material, such as a solder material

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

coupled together through a conductive coupling material, such as a solder material

Methodology Applied

Scientific EffectSoldering: Soldering

Implementation Method 3

breakdown of solder balls connected between the conductor pattern for heat dissipation and the mounting substrate under temperature cyclic loading, primarily due to stress concentration at inflection points

Methodology Applied

Scientific EffectStress concentration: Fracture Mechanics

Data Source

PatentUS9331036B2Semiconductor device

Publication Date: 2016.05.03 RENESAS ELECTRONICS CORP

AI summary

In a semiconductor device, a conductor pattern is disposed in a position overlapped by a semiconductor chip in a thickness direction over the mounting surface (lower surface) of a wiring board. A solder resist film (insulating layer) covering the lower surface of the wiring board has apertures formed such that multiple portions of the conductor pattern are exposed. The conductor pattern has conductor apertures. The outlines of the apertures and the conductor apertures overlap with each other, in a plan view, respectively.