Capped Metal Sintering Powder for Low-Pressure Joint Formation

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Solution Overview

Problem

Current sintering technologies for electronics applications face challenges such as high sintering temperatures, mechanical stress, and difficulty in automation due to the need for high external pressures, which can damage work pieces and result in inconsistent joint formation.

Innovation Solution

A sintering powder comprising metal particles with a mean longest dimension of 100 nm to 50 μm, partially coated with a capping agent, allowing for low-temperature sintering with minimal pressure, reducing agglomeration and residual organics, and enhancing mechanical properties of the sintered joint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If high external pressure is applied during sintering to reduce sintering temperature, then sintering temperature is reduced, but automation becomes difficult and work pieces may be damaged

Engineering Contradiction:

Improvesintering temperatureVSAvoidautomation difficulty

Core Design Contradiction:

TemperatureVSEase of operation

Solution Approach 1:

The patent changes the particle size parameter of the metal powder from conventional larger sizes to nanoscale (1-100 nm diameter), which fundamentally alters the sintering behavior. This parameter change enables sintering to occur at lower temperatures without requiring high external pressure, thereby resolving the contradiction between temperature reduction and ease of operation/automation

Inventive Principle:

Principle #35Parameter changes

2Temperature

If high external pressure is applied during sintering to reduce sintering temperature, then sintering temperature is reduced, but work pieces may be damaged

Engineering Contradiction:

Improvesintering temperatureVSAvoidwork piece damage

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

By changing the particle size parameter to nanoscale dimensions, the patent enables sintering at lower temperatures without the need for high external pressure. This eliminates the harmful effect of work piece damage while achieving the beneficial effect of reduced sintering temperature

Inventive Principle:

Principle #35Parameter changes

3Temperature

If nanomaterials are used to form sintered joints, then sintering temperature is reduced, but residual organics increase

Engineering Contradiction:

Improvesintering temperatureVSAvoidresidual organics

Core Design Contradiction:

TemperatureVSLoss of substance

Solution Approach 1:

The patent optimizes the particle size parameter within the nanoscale range (1-100 nm) and controls the heating rate during sintering. This allows sufficient time for organic binder decomposition and volatilization at the reduced sintering temperature, thereby minimizing residual organics while maintaining the advantage of lower processing temperature

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a controlled heating process that maintains sintering conditions continuously, allowing complete decomposition and removal of organic binders. This continuous heating action ensures thorough elimination of residual organics while achieving dense sintered joints at lower temperatures

Inventive Principle:

Principle #20Continuity of useful action

4Temperature

If smaller metal particles are used to reduce sintering temperature, then sintering temperature is reduced, but agglomeration increases

Engineering Contradiction:

Improvesintering temperatureVSAvoidparticle agglomeration

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The patent introduces an organic binder as an intermediary substance that coats and separates the nanoscale metal particles. This binder prevents direct particle-to-particle contact and agglomeration during handling and sintering, enabling the use of small particle sizes for low-temperature sintering while maintaining particle dispersion stability

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

The solution enables the formation of strong, high-conductivity sintered joints with reduced thermal and mechanical stress, improved automation, and lower residual organics, suitable for die attachment and microelectronic packaging with high thermal cycling stability.

Implementation Method 1

A typical method of forming a sintered joint involves placing a metal powder, often in the form of a powder compact, between two work pieces to be joined and then sintering the metal powder. The resulting atomic diffusion of the metal atoms forms a bond between the two work pieces.

Methodology Applied

Scientific EffectAtomic diffusion: Diffusion