MEMS Package Sidewall Metallization for Solder Joint Reliability

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Solution Overview

Problem

Solder connections in microelectromechanical systems (MEMS) packages are a weakness in extreme temperature conditions, affecting Board Level Reliability during thermal cycle tests.

Innovation Solution

Incorporating a metallic surface on the outside of the side walls of the bottom package, which is soldered to the external printed circuit board along with the solder bumps, increasing the solder area and height for improved reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional solder bumps are used for connecting the package to the external circuit board, then the connection is simple and straightforward, but the reliability deteriorates under extreme temperature conditions

Engineering Contradiction:

ImproveBoard Level ReliabilityVSAvoidpackage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The bottom package is divided into distinct functional regions: a non-metallic portion providing electrical isolation and a metallic surface portion providing enhanced soldering. This segmentation allows each region to perform its specialized function, improving overall reliability without excessive complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bottom package incorporates a localized metallic surface portion with different properties (higher thermal and electrical conductivity) than the surrounding non-metallic material. This local quality change concentrates the reliability enhancement exactly where solder connections are needed, while maintaining simplicity elsewhere

Inventive Principle:

Principle #3Local quality

2Reliability

If the solder bump area is increased to improve reliability, then the thermal and mechanical stress distribution improves, but the package size increases

Engineering Contradiction:

Improvesolder connection reliabilityVSAvoidpackage footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The bottom package uses a composite structure combining non-metallic material (for electrical isolation and mechanical support) with a metallic surface portion (for enhanced soldering). This composite approach increases the effective solder area and improves stress distribution without requiring a larger overall package footprint

Inventive Principle:

Principle #40Composite materials

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 solution enhances Board Level Reliability by providing additional solder connections that withstand extreme temperatures, reducing stress on existing solder bumps and improving the overall performance of MEMS packages.

Implementation Method 1

the metallic surface is also soldered to the external board which results in an increase of the solder area and height

Methodology Applied

Scientific EffectSoldering: Soldering

Data Source

PatentEP4471844A1Electronic component with improved board level reliability

Publication Date: 2024.12.04 MURATA MFG CO LTD

Figure 1a~1b
Figure 2a~2b
Figure 2c~2d

AI summary

The disclosure describes an arrangement that allows Board Level Reliability improvement of microelectromechanical components. The result is achieved by including an outer metallic surface to at least one of the walls of the bottom package. During the process of soldering the electronic component to an external printed circuit board the metallic surface is also soldered to the external board which results in an increase of the solder area and height.