Stack Semiconductor Package Filler Stress Relief

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Solution Overview

Problem

Stack type semiconductor packages face issues with warping, twisting, or distortion during processing due to mechanical and thermal stress, which compromises the reliability of inter-package connectors and overall package stability.

Innovation Solution

A stack type semiconductor package design that includes a lower and upper package substrate with inter-package connectors, where a filler material, such as an epoxy resin or polymer-based material, is used to fill the gap between the substrates, surrounding the connectors to alleviate stress and enhance reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If stack type semiconductor packages are used to improve integration degree and miniaturization, then the degree of integration increases and device size decreases, but the packages warp, twist, or distort during subsequent processing

Engineering Contradiction:

Improvedevice sizeVSAvoidpackage stability

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

A filler material is introduced as an intermediary substance between the lower and upper package substrates. This filler surrounds the inter-package connector and fills the gap between substrates, acting as a mediator that prevents warping and twisting while maintaining the compact stack structure. The filler material provides mechanical support and stress distribution without compromising the miniaturized form factor.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs composite material construction by combining different materials with complementary properties: the package substrates, semiconductor chips, inter-package connectors, and filler materials form a multi-material composite structure. This composite approach allows optimization of each component for its specific function while achieving overall structural stability in the miniaturized package.

Inventive Principle:

Principle #40Composite materials

2Reliability

If inter-package connectors are used to connect upper and lower packages, then electrical connection is achieved, but the connectors are susceptible to shock and thermal cycle stress causing cracked solder joints

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidshock and thermal cycle stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The filler material is positioned beforehand to surround the inter-package connector, creating a protective cushion against upcoming shock and thermal cycle stresses. This prior cushioning prevents direct transmission of mechanical shocks and thermal expansion/contraction forces to the solder joints, preventing cracked solder joints before they can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The filler acts as an intermediary protective layer between the external environment (shock, thermal cycles) and the inter-package connector. It absorbs and distributes harmful stresses, preventing them from reaching the vulnerable solder joints while maintaining electrical connectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the upper package substrate is larger than the lower package substrate, then stacking is enabled, but stress is concentrated on the inter-package connector

Engineering Contradiction:

Improvestacking capabilityVSAvoidstress on inter-package connector

Core Design Contradiction:

Adaptability or versatilityVSStress or pressure

Solution Approach 1:

The filler material serves as a stress-distributing intermediary between the upper and lower package substrates. It fills the gap created by the size difference and surrounds the inter-package connector, distributing the stress over a larger area and preventing concentration on the connector itself.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical parameters of the interface between substrates by introducing filler material with different mechanical properties. This alters the stress distribution characteristics, transforming the stress concentration problem into a distributed stress state that the connector can withstand.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9171827B2Stack type semiconductor package

Publication Date: 2015.10.27 SAMSUNG ELECTRONICS CO LTD

AI summary

A stack type semiconductor package includes a lower semiconductor package including a lower package substrate and at least one lower semiconductor chip disposed on the lower package substrate; an upper semiconductor package including an upper package substrate larger than the lower package substrate and at least one upper semiconductor chip disposed on the upper package substrate; an inter-package connector connecting an upper surface of the lower package substrate to a lower surface of the upper package substrate; and a filler filling in between the lower package substrate and the upper package substrate while substantially surrounding the inter-package connector.