Elastic Flip-Chip Contacts for Reflow-Free Semiconductor Packaging

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing flip-chip packaging technologies for semiconductor devices face challenges in ensuring reliable connections between the device die and the substrate, as the connections are vulnerable and can be compromised by high-temperature reflow processes, which also risk damaging the device.

Innovation Solution

The use of elastic and conductive polymer contacts with conformal profiles, such as doped graphene-polyethylene terephthalate or polyvinyl alcohol, and substrate contacts with matching concave or convex shapes, allows for direct and deformable connections that eliminate the need for reflow processes, enhancing connection reliability and reducing manufacturing complexities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional flip-chip packaging with solder bumps and reflow process is used, then electrical connections between device die and substrate are established, but the connections are vulnerable and reliability is hard to control

Engineering Contradiction:

Improveconnection reliabilityVSAvoidpackaging process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the physical state and material properties of contacts from rigid solder bumps to elastic conductive polymer contacts. This parameter change allows the contacts to deform elastically during attachment, ensuring reliable electrical connection without requiring precise reflow processing, thus improving connection reliability while simplifying the packaging process

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials - specifically conductive polymer contacts that combine elasticity and electrical conductivity. These composite contacts integrate both mechanical compliance for reliable attachment and electrical functionality, eliminating the need for separate solder bump structures and reflow processes

Inventive Principle:

Principle #40Composite materials

2Reliability

If high temperature reflow process is used to join solder bumps, then electrical connections are formed, but the device die may be harmed

Engineering Contradiction:

Improveelectrical connectionVSAvoidthermal damage to device die

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the thermal-based reflow joining process with a mechanical elastic deformation mechanism. The elastic conductive polymer contacts deform under compression to establish electrical connection, substituting the high-temperature thermal field with a low-stress mechanical field that does not damage the device die

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent converts the potential harm of high-temperature processing into benefit by using room-temperature or low-temperature elastic deformation. The elastic contacts provide self-aligning and self-adjusting capabilities during attachment, achieving reliable electrical connection without exposing the device die to harmful thermal conditions

Inventive Principle:

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

3Reliability

If conformal profile contacts with elastic materials are used, then connection reliability is enhanced and reflow process is eliminated, but manufacturing precision requirements increase

Engineering Contradiction:

Improveconnection reliabilityVSAvoidprofile conformity precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic elasticity to the contact structure, allowing the contacts to adapt their shape during attachment. The elastic conductive polymer contacts can deform to match conformal profiles, providing self-aligning capability that reduces the stringency of manufacturing precision requirements while ensuring reliable electrical connection

Inventive Principle:

Principle #15Dynamics

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 provides robust, high-density electrical connections without the need for reflow, reducing manufacturing difficulties and avoiding vulnerabilities associated with traditional flip-chip packaging, while enabling fine-pitch bump technologies and improved I/O density.

Implementation Method 1

Either or both of the at least one device contact and the at least one substrate contact are elastic

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The at least one device contact is in direct contact with a corresponding one of the at least one substrate contact

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS20250385173A1Packaged semiconductor device and method for packaging

Publication Date: 2025.12.18 NXP USA INC

AI summary

A packaged semiconductor device includes a device die, at least one device contact, a substrate, and at least one substrate contact. The device die has a first device side and a second device side opposite to the first device side. The at least one device contact is arranged on the first device side of the device die. The substrate has a first substrate side and a second substrate side opposite to the first substrate side. The at least one substrate contact is arranged on the first substrate side of the substrate. The device die is attached to the substrate with the first device side facing the first substrate side. The at least one device contact is in direct contact with a corresponding one of the at least one substrate contact. Either or both of the at least one device contact and the at least one substrate contact are elastic.