Integrated Circuit Packaging With Underfill Barrier

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Solution Overview

Problem

Current package-on-package (PoP) structures face challenges with inadequate mechanical robustness, thermal performance, and inefficient underfill processes, leading to issues such as insufficient solder joint reliability, excessive material waste, and complex dispensing times in integrated circuit packaging.

Innovation Solution

The proposed integrated circuit packaging system includes a base substrate with a barrier to prevent underfill overflow, a stack substrate with an aperture for connector underfill dispensing, and a thermal interface layer to enhance mechanical and thermal performance, using a connector underfill to encapsulate inter-substrate connectors and improve warpage control and thermal dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If connector underfill is dispensed without a barrier structure, then the underfill process is simpler, but underfill material overflows and causes waste and contamination

Engineering Contradiction:

Improveunderfill material wasteVSAvoidbarrier structure complexity

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The base substrate is segmented by introducing a barrier structure that divides the substrate surface into a dispensing region and a barrier region. This segmentation contains the underfill material within the dispensing region during dispensing, preventing overflow onto other components while allowing simple dispensing operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The barrier structure acts as an intermediary element between the underfill dispensing process and the rest of the substrate. It mediates the flow of underfill material, allowing controlled dispensing while blocking unwanted overflow, thus eliminating the need for complex dispensing control mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If traditional PoP structures are used without enhanced barrier design, then manufacturing is simpler, but solder joint reliability is insufficient

Engineering Contradiction:

Improvesolder joint reliabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The barrier structure is formed on the base substrate before the underfill dispensing step. This preliminary action pre-establishes the containment boundaries, ensuring that when underfill is dispensed, it automatically flows only to the intended area. This prevents solder joint contamination and improves reliability without requiring complex real-time control during dispensing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The barrier structure creates local quality differentiation on the base substrate surface, with the barrier region having different properties (acting as a wall) from the dispensing region. This local modification ensures proper underfill containment only where needed, maintaining simplicity in other areas while improving solder joint reliability.

Inventive Principle:

Principle #3Local quality

3Productivity

If underfill dispensing is performed without regional differentiation, then the process is faster, but underfill overflows causing contamination and waste

Engineering Contradiction:

Improveunderfill dispensing speedVSAvoidunderfill material waste

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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 mechanical integrity, improves solder joint reliability, reduces material waste, and simplifies the underfill process, while also improving thermal performance and reliability under temperature cycling and mechanical impact tests.

Implementation Method 1

dispensing a connector underfill through the stack substrate aperture encapsulating the inter-substrate connector

Methodology Applied

Scientific EffectEncapsulation:

Implementation Method 2

overflow of the connector underfill prevented by the base barrier

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 3

a thermal interface layer to enhance mechanical and thermal performance, using a connector underfill to encapsulate inter-substrate connectors and improve warpage control and thermal dissipation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS8624364B2Integrated circuit packaging system with encapsulation connector and method of manufacture thereof

Publication Date: 2014.01.07 STATS CHIPPAC LTD

AI summary

An integrated circuit packaging system includes: a base integrated circuit package having a base integrated circuit on a base substrate thereof; a base barrier on the base substrate adjacent a base perimeter of the base substrate; a stack substrate over the base substrate, the stack substrate having a stack substrate aperture with the stack substrate having an inter-substrate connector thereon; a connector underfill through the stack substrate aperture encapsulating the inter-substrate connector, overflow of the connector underfill prevented by the base barrier; and a cavity formed of the stack substrate, the base integrated circuit package, and the connector underfill, the cavity horizontally offset from the base barrier.