SiP Conductive Post Assembly for High-Density Component Spacing

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Solution Overview

Problem

The existing system-in-package (SiP) semiconductor devices face challenges in achieving high density electrical components due to the leakage of solder paste during reflow, leading to unintended electrical connections and the need for increased spacing to avoid short circuits, which reduces layout density.

Innovation Solution

The use of flux material deposited on conductive posts within the SiP allows for narrow spacing between electrical components by vaporizing during reflow, preventing material leakage and enabling self-alignment, thus eliminating the need for solder paste and reducing the risk of short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solder paste is used to make electrical connection between components and substrate, then electrical connection is achieved, but solder paste leaks out during reflow causing unintended electrical connections and requiring greater spacing between components

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidspacing between components

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent extracts and removes the harmful solder paste material from the connection process, replacing it with flux material that vaporizes during reflow. This eliminates the leakage problem while maintaining electrical connection functionality, allowing components to be placed closer together without risk of unintended connections.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the physical and chemical parameters of the connection material from solder paste (which remains as solid residue) to flux material (which vaporizes completely). This parameter change in material behavior during reflow eliminates the spacing requirement needed to prevent solder paste leakage, thereby reducing component spacing.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If greater spacing is provided between electrical components to avoid short circuits from solder paste leakage, then electrical short circuit risk is reduced, but layout density of electrical components decreases

Engineering Contradiction:

Improveshort circuit preventionVSAvoidlayout density of components

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

By removing solder paste from the process and using flux material that vaporizes instead, the patent eliminates the source of leakage that causes short circuits. This allows components to be densely packed without the safety margin spacing previously required, thereby increasing layout density while maintaining short circuit prevention.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potential harm of material leakage during reflow into a benefit by using flux material that is designed to vaporize completely. The vaporization process provides beneficial self-alignment of components while eliminating the harmful leakage effect, enabling higher density layouts.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Quantity of substance

If flux material is used instead of solder paste, then component spacing can be reduced for higher density, but new material deposition process is required

Engineering Contradiction:

Improvecomponent densityVSAvoidmaterial deposition process

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent introduces flux material as an intermediary substance that performs the function of temporary bonding during assembly, then vaporizes to leave no residue. This intermediary material enables the reduced spacing and higher density while the deposition process, though new, is simplified by the material's complete vaporization eliminating cleanup requirements.

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 allows for higher density electrical components per unit area with reduced spacing, minimizing defects and process costs, while maintaining mechanical and electrical attachment of components.

Implementation Method 1

The use of flux material deposited on conductive posts within the SiP allows for narrow spacing between electrical components by vaporizing during reflow

Methodology Applied

Scientific EffectVaporization: Evaporation

Data Source

PatentUS20230402383A1Semiconductor Device and Method of Providing High Density Component Spacing

Publication Date: 2023.12.14 STATS CHIPPAC LTD

AI summary

A semiconductor device has a substrate and a first conductive layer formed over the substrate. A second conductive layer is formed over the first conductive layer. The first conductive layer can be copper, and the second conductive layer can be nickel. A thickness of the second conductive layer is greater than a thickness of the first conductive layer. A flux material is deposited over the second conductive layer by a printing process. An electrical component is disposed over the flux material, and the flux material is reflowed to make electrical connection between the electrical component and second conductive layer. The flux material substantially vaporizes during the reflow to reduce the occurrence of short circuits. The electrical components can be placed over the substrate with narrow spacing and higher density given the use of the flux material to make electrical connection. An encapsulant is deposited over the electrical component.