Stacking Balls Package Fabrication Prevents Underfill Contamination

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Solution Overview

Problem

The existing methods for forming electronic component packages restrict the size of flip chip mounted components due to the need for sufficient spacing between ball terminals and the component to prevent underfill bleeding and contamination, limiting the minimal size of the component that can be placed within a fixed pattern of ball terminals.

Innovation Solution

The formation of stacking balls on the ball terminals before applying underfill allows for minimal spacing between the ball terminals and the electronic component, preventing underfill contamination and enabling a larger component size within the fixed pattern, as the underfill directly contacts and encloses the inner row of stacking balls closest to the component.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ball terminals are spaced a sufficient distance from the flip chip mounted electronic component to prevent underfill bleeding and contamination, then underfill contamination is prevented, but the allowable size of the electronic component is fundamentally limited

Engineering Contradiction:

Improveprevention of underfill contaminationVSAvoidsize of electronic component

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

Stacking balls are formed on ball terminals prior to the application of underfill material. This preliminary action creates a protective structure that prevents underfill from contacting and contaminating the ball terminals, allowing the underfill to be applied closer to the electronic component without causing contamination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The stacking balls serve as an intermediary structure between the underfill material and the ball terminals. They physically block the underfill from reaching the ball terminals while allowing the underfill to enclose the stacking balls, thus preventing contamination without requiring large spacing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of moving object

If ball terminals are spaced closer to the flip chip mounted electronic component to increase component size, then the allowable component size is increased, but underfill will bleed onto and contaminate the ball terminals

Engineering Contradiction:

Improvesize of electronic componentVSAvoidunderfill contamination

Core Design Contradiction:

Area of moving objectVSObject-affected harmful factors

Solution Approach 1:

The stacking balls are formed on the ball terminals before underfill application, creating a pre-established barrier that prevents underfill contamination even when terminals are spaced closely to the electronic component.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Stacking balls act as an intermediary barrier that allows close spacing between ball terminals and the electronic component while preventing underfill from contacting the ball terminals, thus enabling larger component sizes without contamination risk.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If sufficient spacing is maintained between ball terminals and the electronic component, then underfill contamination is prevented, but the overall package size increases

Engineering Contradiction:

Improveprevention of underfill contaminationVSAvoidoverall package size

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

By forming stacking balls before underfill application, the patent eliminates the need for excessive spacing, thereby minimizing the overall package size while maintaining contamination prevention.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The stacking balls serve as a compact intermediary structure that prevents underfill contamination without requiring large spacing, thus minimizing the overall package volume while maintaining reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8890337B1Column and stacking balls package fabrication method and structure

Publication Date: 2014.11.18 AMKOR TECH SINGAPORE HLDG PTE LTD

AI summary

Stacking balls are formed on ball terminals prior to application of an underfill under a flip chip mounted electronic component. The underfill is then applied and directly contacts and at least partially encloses an inner row of the stacking balls closest to and directly adjacent the flip chip mounted electronic component. By forming the stacking balls prior to the application of the underfill, contamination of the ball terminals by the underfill is avoided. This allows the spacing between the ball terminals and the electronic component to be minimized.