Flexible Heat Conduction Braid Joints That Block Solder Wicking

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Solution Overview

Problem

Existing thermal conduction devices in aerospace and aeronautics face challenges with inflexible metal braids due to solder migration and oxidation during flame brazing, making them inefficient for heat dissipation in satellites.

Innovation Solution

The use of electrically compacted metal braids with crimped tubes to prevent solder migration, combined with furnace brazing (diffusion brazing) to maintain flexibility and avoid oxidation, ensuring effective heat conduction without stiffening the braids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If flame brazing is used to secure metal braids to thermally conductive parts, then the braids can be connected to the parts, but the braids become stiffened and lose flexibility due to solder migration

Engineering Contradiction:

Improveconnection strengthVSAvoidflexibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The free ends of the metal braids are electrically compacted before the brazing operation to reduce porosity and prevent solder migration during subsequent flame brazing, thereby preserving braid flexibility while ensuring strong connections

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A flux composition is used as an intermediary substance during brazing that facilitates solder flow and wetting while controlling migration into the braids, allowing strong connections without sacrificing flexibility

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If flame brazing is used to connect metal braids, then the connection can be formed, but oxidation occurs on the braid yarns and parts during the process

Engineering Contradiction:

Improveconnection strengthVSAvoidoxidation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

A flux composition is applied to create a protective atmosphere during flame brazing that prevents oxidation of the metal braids and thermally conductive parts while allowing the brazing process to proceed effectively

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

3Strength

If flame brazing is used to secure the braids, then the connection can be made, but the process becomes difficult and inefficient due to the circular shape and small dimensions of the braids

Engineering Contradiction:

Improveconnection strengthVSAvoidbrazing ease

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The free ends of the metal braids are electrically compacted before brazing to create a more manageable structure that is easier to position and secure in the small circular holes, simplifying the overall manufacturing process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Electrical compaction is used to replace or supplement the mechanical brazing process, providing a more effective and easier method for preparing the braid ends before connection

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 flexible thermal conduction devices with no oxidation traces, suitable for aerospace applications, by preventing solder migration and maintaining braids' flexibility through crimped tubes and controlled brazing processes.

Implementation Method 1

a thermal conduction device comprising at least two thermally conductive parts (1a, 1b) provided with holes (2a, 2b) and a plurality of thermally conductive metal braids (3)

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The free ends of the braids (3) are electrically compacted

Methodology Applied

Scientific EffectElectrical compaction:

Implementation Method 3

furnace brazing (diffusion brazing) to maintain flexibility and avoid oxidation

Methodology Applied

Scientific EffectFurnace brazing: Brazing

Implementation Method 4

furnace brazing (diffusion brazing)

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 5

The tubes crimped to the free ends of the metal braids (3) provide a barrier against the filler metal during brazing

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Implementation Method 6

a large part of the solder rises in the braids by capillarity

Methodology Applied

Scientific EffectCapillarity: Capillary Action

Implementation Method 7

the time of exposure to the flame deteriorates the wires of the braid and the parts on which the braids are welded. This deterioration essentially consists of oxidation of the braid yarns

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentEP2781454B1Heat-conduction device and method for manufacturing same

Publication Date: 2019.01.02 TRESSE METALLIQUE J FORISSIER

Figure 1~2
Figure 3A~3F

AI summary

The device has two thermally conductive parts (1a, 1b) provided with holes (2a, 2b) and thermally conductive metal braids (3) whose free ends are welded in the holes of the parts. The free ends of the metal braids are electrically compacted, where each free end includes a crimped tube having an outer diameter just lower than an inner diameter of the holes of the parts, so as to prevent the solder from rising by capillarity into the braids during welding. The crimped tubes cover the holes of the conductive parts. An independent claim is also included for a method for manufacturing a thermal conduction device.