Underfill Flow Guide Structures for Bubble-Free Electronic Modules

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Solution Overview

Problem

Existing underfill applications in electronic modules face challenges in achieving complete filling without trapped bubbles, particularly in miniaturized power electronic structures, due to thermomechanical and insulation requirements.

Innovation Solution

The use of arc-shaped structural elements within the electronic module gap, designed to guide underfill material effectively and minimize bubble formation, combined with strategic placement and orientation to ensure complete filling and efficient flow management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional underfill application methods are used, then the process is simple, but trapped bubbles and incomplete filling occur at critical points

Engineering Contradiction:
Improvefilling completenessVSAvoidstructural element arrangement
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Guide structures are introduced as intermediary elements within the gap to mediate the flow of underfill material. These structures create defined flow paths that guide the liquid underfill from the application point to all critical areas, preventing trapped bubbles and ensuring complete filling of the gap between substrates and semiconductor components.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The gap space is segmented into multiple flow channels by the guide structures. Instead of allowing random flow, the guide structures divide the filling process into controlled segments, with each channel directing underfill to specific regions, ensuring systematic and complete coverage without air entrapment.

Inventive Principle:
Principle #1Segmentation

2Productivity

If underfill is applied quickly to reduce process time, then productivity increases, but bubble formation and flow defects increase

Engineering Contradiction:
Improveprocess timeVSAvoidbubble formation
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The guide structures serve as flow mediators that control and direct the underfill material during rapid application. By providing predefined flow paths, these structures enable fast dispensing while maintaining orderly flow that prevents bubble entrapment, thus allowing high productivity without sacrificing filling quality.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The guide structures are pre-positioned in the gap before underfill application. This preliminary arrangement of flow paths ensures that when underfill is rapidly applied, the material immediately follows the predetermined channels, preventing random flow patterns and bubble formation even during quick processing.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the gap is completely filled to ensure insulation and stability, then reliability improves, but air inclusions and outgassing defects occur

Engineering Contradiction:
Improveinsulation and stabilityVSAvoidtrapped air and outgassing
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

Guide structures act as intermediary flow directors that enable complete gap filling while systematically expelling air. The structures create flow paths that push air bubbles toward escape routes at the periphery, allowing the gap to be completely filled with underfill material without trapping air inclusions that would compromise insulation and stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Manufacturing precision

If structural elements are added to guide underfill flow, then filling quality improves, but device complexity and manufacturing steps increase

Engineering Contradiction:
Improveunderfill distributionVSAvoidmanufacturing process
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The guide structures serve multiple functions simultaneously: they guide underfill flow, define flow channels, prevent bubble formation, and remain as part of the final module structure. This multi-functionality justifies the additional manufacturing steps by providing comprehensive benefits in filling quality and device performance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The guide structures are integrated into the module assembly, merging the flow guidance function with the structural components of the electronic module. Rather than being temporary fixtures removed after filling, the guide structures become permanent parts of the module, combining structural support with flow guidance functionality.

Inventive Principle:
Principle #5Merging (Combining)

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 approach ensures complete underfilling with minimal bubble formation, enhancing insulation and stability in electronic modules by optimizing the flow and distribution of underfill material.

Implementation Method 1

The invention is based on underfills for capillary flow underfill applications

Methodology Applied
Scientific EffectCapillary flow: Capillary Action

Data Source

PatentEP4340005A1Underfilled electronic module with flow direction guide structures
Publication Date: 2024.03.20 SIEMENS AG
  • EP4340005A1 patent drawingFigure 1~2
  • EP4340005A1 patent drawingFigure 3~4
  • EP4340005A1 patent drawingFigure 5~6

AI summary

The invention relates to an electronic module (100) comprising at least a first substrate (10), a second substrate (20) and semiconductor components (30) arranged between the first and the second substrate (10, 20), which are attached to the first substrate (10) and to the second substrate (20), further comprising a subfill (50) which at least partially fills a gap (40) between the semiconductor components (30) and substrates (10, 20) and structural elements (60,...,65) which are arranged in the gap (40) and are at least partially surrounded by the subfill (50).