Capillary Underfill for Microelectronics Gap Filling

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Solution Overview

Problem

Conventional capillary underfill methods struggle with filling gaps between electronic devices and substrates with pitches less than 100 micrometers and gaps less than 50 micrometers, leading to back pack phenomenon, bubble formation, and reliability issues, which hinder electronic device miniaturization.

Innovation Solution

A method involving applying capillary underfill to multiple sides of electronic devices, followed by controlled temperature and pressure adjustments in a processing chamber to reduce and eliminate bubbles, using a multi-stage pressure and temperature modulation to ensure effective filling and protection of conductive bumps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If capillary underfill is applied to one single side of the electronic device to prevent back pack phenomenon, then back pack phenomenon is reduced, but filling rate becomes slow and control of creeping speed becomes difficult

Engineering Contradiction:

Improveback pack phenomenon preventionVSAvoidfilling rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The underfill application is divided into multiple sides (at least two sides) of the electronic device, allowing simultaneous filling from multiple directions. This segmentation enables faster overall filling while distributing the complexity of controlling creeping speed across multiple controlled interfaces, resolving the contradiction between preventing back pack phenomenon and maintaining high filling rate.

Inventive Principle:

Principle #1Segmentation

2Length of moving object

If pitch between conductive bumps is reduced to enable miniaturization, then electronic device size is reduced, but gap filling becomes more difficult and back pack phenomenon increases

Engineering Contradiction:

Improveelectronic device sizeVSAvoidgap filling precision

Core Design Contradiction:

Length of moving objectVSManufacturing precision

Solution Approach 1:

The filling approach transitions from one-dimensional (single side) to multi-dimensional (multiple sides) underfill application. By applying underfill to at least two sides simultaneously, the patent achieves effective gap filling in miniaturized devices with reduced pitch while preventing back pack phenomenon through multi-directional creeping control, thus resolving the contradiction between miniaturization and manufacturing precision.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If capillary underfill is applied to multiple sides of the electronic device to improve filling rate, then filling speed increases, but bubble formation and back pack phenomenon increase

Engineering Contradiction:

Improvefilling rateVSAvoidbubble formation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements a multi-stage pressure and temperature control process with real-time monitoring and adjustment. By controlling pressure to transition from negative to positive and adjusting temperature accordingly, the system provides feedback control that manages underfill creeping speed and direction, enabling multi-side application that increases filling rate while preventing bubble formation and back pack phenomenon through controlled parameter modulation.

Inventive Principle:

Principle #23Feedback

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 enables reliable filling of small gaps, reduces bubble formation, and promotes electronic device miniaturization by ensuring proper capillary underfill application and bubble elimination, enhancing the reliability and efficiency of the manufacturing process.

Implementation Method 1

a capillary underfill is applied to one or more sides of the electronic devices, enabling the underfill to creep along the gaps between the electronic devices and the substrate

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

raising the temperature in the chamber to a first predetermined temperature; reducing the pressure in the chamber to a first predetermined pressure of vacuum pressure

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

raising the pressure in the chamber to a second predetermined pressure higher than 1 atm, and maintaining the second predetermined pressure for a predetermined time period

Methodology Applied

Scientific EffectCompression: Compression

Data Source

PatentUS10251281B2Method for manufacturing electronic devices

Publication Date: 2019.04.02 ABLEGO TECHNOLOGY CO LTD

AI summary

This invention provides a method and apparatus for manufacturing electronic devices. The method includes: providing a substrate having a first surface; providing an electronic device having bumps; mounting the bumps to the first surface to form an integrated unit; applying a capillary underfill to multiple sides of the electronic device, enabling the underfill to creep along and fill the gap between the electronic device and the substrate; placing the integrated unit into a processing chamber; raising the temperature in the chamber to a first predetermined temperature; reducing the pressure in the chamber to a first predetermined pressure of a vacuum pressure, and maintaining the vacuum pressure for a predetermined time period; raising the pressure in the chamber to a second predetermined pressure higher than 1 atm, and maintaining the second predetermined pressure for a predetermined time period; and adjusting the temperature in the chamber to a second predetermined temperature.