Hollow Metal Inserts for Face-to-Face Hybridization

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Solution Overview

Problem

Current methods for 'flip chip' hybridization using metal-in-metal insertion face challenges in reducing interconnection pitch due to complex manufacturing processes and limitations in etching precision, leading to poor electrical connections and high costs.

Innovation Solution

The method involves creating hollow metal inserts with a stainless metal layer covering only the internal surface, using a first sub-layer with higher plasticity and a second sub-layer with lower plasticity to facilitate insertion and electrical connection without noble metals, allowing for reduced interconnection pitch and cost-effective manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a layer of noble metal is deposited on the entire plate and then etched between inserts, then the electrical connection quality is improved, but the interconnection pitch cannot be reduced and manufacturing complexity increases

Engineering Contradiction:
Improveelectrical connection qualityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by depositing the noble metal layer only on the internal surface of the inserts where it is needed for electrical contact, rather than coating the entire insert surface. This selective localization eliminates the need for complex etching processes to remove metal between inserts, as the metal simply isn't deposited in those areas to begin with.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses preliminary action by forming the inserts as hollow structures before depositing the noble metal layer. This preliminary hollow structure creation allows the subsequent metal deposition to occur only on the internal surface, preventing metal accumulation between inserts and eliminating the need for post-deposition etching operations.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If noble metals are used to cover inserts, then oxidation is prevented and electrical connections are improved, but costs increase and sensitivity to inter-diffusion and contamination increases

Engineering Contradiction:
Improveoxidation resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent reduces material cost by applying the expensive noble metal layer only where it is functionally necessary - on the internal surface of the inserts that contacts the pad - rather than coating the entire external surface. This localized application significantly reduces the quantity of noble metal required while maintaining oxidation resistance at the critical interface.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent replaces expensive noble metal coatings on the entire insert surface with a more economical approach: a thin noble metal layer only on the internal surface. The external surface can use cheaper materials or remain uncoated, effectively substituting expensive materials with cheaper alternatives where the expensive material is not functionally required.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Productivity

If the interconnection pitch is reduced, then the manufacturing efficiency is improved, but the etching precision requirements increase and manufacturing complexity increases

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidetching precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent extracts the problematic etching operation from the manufacturing process entirely. By depositing the noble metal layer only on the internal surface of pre-formed hollow inserts, the method eliminates the need for precision etching to remove metal between inserts, thereby removing the constraint on interconnection pitch reduction.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent inverts the conventional sequence and approach: instead of coating the entire surface and then etching away excess material, it directly deposits material only where needed on the internal surface. This inverted approach transforms a precision-subtractive process into a controlled additive process that is less sensitive to pitch reduction.

Inventive Principle:
Principle #13The other way round (Inversion)

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 enables the reduction of interconnection pitch to less than 10 micrometers, improving electrical connection quality and manufacturing efficiency while avoiding the use of noble metals, thus reducing costs and sensitivity to inter-diffusion and contamination.

Implementation Method 1

The first sub-layer has a plasticity greater than that of the core, and the second sub-layer has a plasticity lower than that of the first sub-layer

Methodology Applied
Scientific EffectPlasticity: Plasticity

Implementation Method 2

the first sub-layer with higher plasticity and a second sub-layer with lower plasticity to facilitate insertion and electrical connection

Methodology Applied
Scientific EffectDeformation: Deformation

Data Source

PatentEP2727144B1Method for connecting a component equipped with hollow inserts
Publication Date: 2020.08.05 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP2727144B1 patent drawingFigure 1~2
  • EP2727144B1 patent drawingFigure 3~6
  • EP2727144B1 patent drawingFigure 7~10

AI summary

The invention relates to an electromechanical connecting component (10) equipped, on a connecting face, with conductive inserts (72) intended to be inserted into respective conductive pads (18) arranged on a face of another connecting component (12) for face-to-face hybridization. Each insert (72) of the component (10) comprises: a hollow metal core (50) formed by a base placed on the connecting face (14), and a sidewall protruding from said base and defining an internal surface of the insert (72), at least one portion of said internal surface being unoxidized; and a metal layer (70) covering substantially only the internal surface of the metal core (50). According to one embodiment, the metal layer (70) comprises a first underlayer (80) of an oxidizable metal and a second underlayer (82) of a native oxide of the metal forming the first underlayer (80).