Polymer Molding Compound for PoP Warpage Control

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Solution Overview

Problem

Conventional package-on-package (PoP) techniques face challenges in eliminating warpage caused by thermal stress and expansion mismatch between components, despite the use of underfills and interposers.

Innovation Solution

The introduction of a molding compound to provide mechanical stiffness and strength, surrounding conductive elements and encapsulating components, along with the use of underfills to reinforce conductive elements and enhance thermal conductivity, helps control warpage and improve structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional package-on-package techniques are used with underfills and interposers, then component mounting is achieved, but warpage caused by thermal stress and expansion mismatch cannot be entirely eliminated

Engineering Contradiction:

Improvestructural integrityVSAvoidwarpage

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The patent modifies the material composition and physical properties of the molding compound to achieve optimal thermal expansion characteristics. By adjusting the polymer matrix composition, filler content, and crosslinking density, the molding compound's thermal expansion coefficient is tuned to better match the semiconductor chip and interposer, reducing thermal stress and warpage during temperature cycling

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite molding compound consisting of a polymer matrix combined with specific fillers and additives. This composite structure provides both mechanical support and controlled thermal expansion properties, creating a multi-functional material that simultaneously addresses structural integrity and warpage control requirements

Inventive Principle:

Principle #40Composite materials

2Shape

If molding compound is added to provide mechanical stiffness, then warpage control improves, but device complexity increases

Engineering Contradiction:

Improvewarpage controlVSAvoidstructure complexity

Core Design Contradiction:

ShapeVSDevice complexity

Solution Approach 1:

The patent integrates multiple functions into the molding compound itself. The molding compound simultaneously provides mechanical support, warpage control through controlled thermal expansion, encapsulation of conductive elements, and structural integration with the package substrate and interposer. This consolidation eliminates the need for separate components, reducing overall device complexity while maintaining warpage control

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If underfill is used to prevent cracks in solder bumps, then reliability improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvesolder bump integrityVSAvoidunderfill dispensing precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent positions the molding compound as an intermediary structure that provides mechanical support and stress distribution before underfill application. This preliminary structural support reduces the stress concentration on solder bumps, allowing the underfill to work more effectively with relaxed precision requirements for its dispensing and curing process

Inventive Principle:

Principle #24Intermediary (Mediator)

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 reduces the severity of warpage and improves mechanical strength and thermal conductivity, effectively addressing thermal expansion mismatch issues while reducing manufacturing costs.

Implementation Method 1

The thermal stress and warpage are caused by thermal expansion mismatch between the components of a package-on-package structure

Methodology Applied

Scientific EffectThermal expansion mismatch: Thermal Expansion

Implementation Method 2

The thermal stress and warpage are caused by thermal expansion mismatch between the components of a package-on-package structure

Methodology Applied

Scientific EffectThermal stress: Thermal Expansion

Implementation Method 3

along with the use of underfills to reinforce conductive elements and enhance thermal conductivity

Methodology Applied

Scientific EffectThermal conductivity: Conduction (thermal)

Data Source

PatentUS11133285B2Package-on-package structure having polymer-based material for warpage control

Publication Date: 2021.09.28 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure, in some embodiments, relates to a method of forming a package. The method includes coupling a first package component to a second package component using a first set of conductive elements. A first polymer-comprising material is formed over the second package component and surrounding the first set of conductive elements. The first polymer-comprising material is cured to solidify the first polymer-comprising material. A part of the first polymer-comprising material is removed to expose an upper surface of the second package component. The second package component is coupled to a third package component using a second set of conductive elements that are formed onto the upper surface of the second package component.