Stacked Structure With Metallic Cores For Fine Pitch Bonding

Solution Overview

Problem

The challenge in assembling components with fine pitch electronic products is the oxidation of copper surfaces during bonding, leading to unreliable connections due to remaining spaces between bonding points, which affects the reliability and performance of microscale or nanoscale electrical connections.

Innovation Solution

A stacked structure is created using a first circuit board with bonding pads and an electronic component, where metallic cores with insulating cladding layers are physically connected through a thermo-compression process, filling the remaining spaces and preventing oxidation, and the insulating cladding layers flow to protect the connection points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If copper-to-copper bonding is used to bond components of fine pitch, then electrical connections can be established, but oxidation of copper surface occurs before bonding which creates remaining spaces between connection points, worsening bonding reliability

Engineering Contradiction:

Improvebonding reliabilityVSAvoidoxidation of copper surface

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-coating the copper bonding pads with a nickel underlayer before the bonding process. This nickel layer is deposited in advance to prevent oxidation of the copper surface during the bonding operation, thereby eliminating the harmful oxidation effect that would otherwise create voids and reduce bonding reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces nickel as an intermediary material between the copper bonding pads. This nickel underlayer acts as a protective mediator that prevents direct exposure of copper to oxygen, thereby preventing oxidation while maintaining electrical conductivity and bonding capability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Length of moving object

If bonding is performed at microscale or nanoscale dimensions, then electrical connections can be made in compact electronic products, but process yield becomes highly sensitive to external factors, worsening manufacturing reliability

Engineering Contradiction:

Improvebonding pad dimensionVSAvoidprocess yield

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-coating the copper bonding pads with a nickel underlayer before the bonding process. This nickel layer is deposited in advance to prevent oxidation of the copper surface during the bonding operation, thereby eliminating the harmful oxidation effect that would otherwise create voids and reduce bonding reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces nickel as an intermediary material between the copper bonding pads. This nickel underlayer acts as a protective mediator that prevents direct exposure of copper to oxygen, thereby preventing oxidation while maintaining electrical conductivity and bonding capability

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 method effectively forms reliable electrical connections by preventing oxidation and filling the spaces between bonding points, enhancing the assembly reliability of fine pitch components by using metallic cores and insulating cladding layers in the thermo-compression bonding process.

Implementation Method 1

bonding a plurality of second bonding pads of an electronic component to the core-shell particles on the first bonding pads using a thermo-compression process such that the metallic cores are physically connected to the second bonding pads and the first bonding pads

Methodology Applied

Scientific EffectThermo-compression:

Implementation Method 2

the insulating cladding layers flow to protect the connection points

Methodology Applied

Scientific EffectFlow:

Data Source

PatentUS10588214B2Stacked structure and method for manufacturing the same

Publication Date: 2020.03.10 UNIMICRON TECH CORP

AI summary

A stacked structure includes a circuit board, an electronic component, metallic cores, and insulating cladding layers. The circuit board includes first bonding pads. The electronic component includes second bonding pads that are opposite to the first bonding pads. Each metallic core is connected to a corresponding first bonding pad and a corresponding second bonding pad. The metallic cores have a curved surface interposed between the corresponding first bonding pad and the corresponding second bonding pad. The insulating cladding layers are separated from each other and cover the curved surfaces of the metallic cores.