Solder Joint Electrical Connection Sealed with Ceramic Cement

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Solution Overview

Problem

Existing electrical connections for high-temperature applications, such as those using surface elastic wave temperature sensors, face challenges with crimping techniques that are not suitable for monocrystalline substrates and result in thermal differential stresses, and silver paste contacts that suffer from excessive electrical losses and mechanical resistance issues above 500°C.

Innovation Solution

An electrical device with a conductive connection using platinum or gold wires connected by a solder joint on an alumina plate, sealed with a ceramic cement that maintains the connection even when the solder is in a liquid state, ensuring mechanical retention and electrical integrity at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If crimping techniques are used to connect components, then electrical connection is achieved, but the connection cannot be used on monocrystalline substrates at high temperatures and induces thermal differential stresses

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidcompatibility with monocrystalline substrates
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces an intermediary material (solder joint) between the metal elements that can accommodate thermal expansion differences. This solder joint acts as a buffer that absorbs thermal differential stresses while maintaining electrical connection, enabling compatibility with monocrystalline substrates at high temperatures where crimping fails.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the connection method from mechanical crimping to thermal soldering, fundamentally altering the joining parameters. This parameter change enables the connection to withstand high temperatures (above 230°C) and be compatible with monocrystalline substrates, resolving both the reliability and adaptability issues simultaneously.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If crimping techniques are used to connect components, then electrical connection is achieved, but rigid connection induces thermal differential stresses prohibitive for device integrity

Engineering Contradiction:
Improveelectrical connection stabilityVSAvoiddevice integrity under thermal stress
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by making the solder joint material different from the metal elements it connects. The solder material is specifically chosen to have properties that provide both electrical conductivity and thermal stress absorption, creating a localized zone that manages thermal differential stresses while maintaining overall connection stability.

Inventive Principle:
Principle #3Local quality

3Reliability

If silver paste type contacts are used, then electrical connection is achieved, but excessive electrical losses and lack of mechanical resistance occur above 500°C

Engineering Contradiction:
Improveelectrical connection functionalityVSAvoidelectrical losses
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the short-lived silver paste contact (which degrades above 500°C) with a more durable solder joint connection. The solder joint is designed to maintain both electrical conductivity and mechanical strength at high temperatures, eliminating the excessive electrical losses and mechanical resistance issues that plague silver paste contacts in high-temperature environments.

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

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 provides a reliable and durable electrical connection resistant to high temperatures, maintaining mechanical and electrical integrity even when the solder joint is in a liquid state, allowing operation beyond 600°C without significant disturbance or failure.

Implementation Method 1

connecting the second end of the first metal element and the fourth end of the second metal element by a solder joint deposited on the support plate

Methodology Applied
Scientific EffectSoldering: Soldering

Implementation Method 2

sealed with a ceramic cement that maintains the connection even when the solder is in a liquid state

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2839259B1Electrical device and method for producing the same
Publication Date: 2019.11.20 CENT NAT DE LA RECH SCI (C N R S)
  • EP2839259B1 patent drawingFigure 1~2
  • EP2839259B1 patent drawingFigure 3~4
  • EP2839259B1 patent drawingFigure 5~6

AI summary

An electrical device and method for producing same. The electrical device (2, 202) comprises a first electrical component (4) and a second electrical component (6) connected to each other via an electrical connection means (26) having an electrically insulating support plate (24), and a weld joint (22) deposited on the support plate (24). The weld joint (22) has a melting temperature (Tf) significantly lower than an ambient operating temperature (Ta) to which at least one of the two electrical components and the electrical connection means (26) are expected to be subjected. The electrical device (2) comprises a cement (28) which completely covers the exposed weld joint (22), the cement material (28) being chosen to maintain the adhesion and sealing of same with regard to the weld joint (22) when the ambient operating temperature (Ta) is applied. The electrical device (2, 202) comprises a first electrical component (4) and a second electrical component (6) connected to each other via an electrical connection means (26) having an electrically insulating support plate (24), and a weld joint (22) deposited on the support plate (24). The weld joint (22) has a melting temperature (Tf) significantly lower than an ambient operating temperature (Ta) to which at least one of the two electrical components and the electrical connection means (26) are expected to be subjected. The electrical device (2) comprises a cement (28) which completely covers the exposed weld joint (22), the cement material (28) being chosen to maintain the adhesion and sealing of same with regard to the weld joint (22) when the ambient operating temperature (Ta) is applied.