Sublimable Sacrificial Structures for Hollow 3D Printing

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Solution Overview

Problem

Existing layer-by-layer 3D printing techniques face issues with sacrificial materials that require solvent-based or high-temperature removal, leading to stiction and residue problems due to capillary forces and decomposition.

Innovation Solution

The use of sublimable materials like cyclododecane, which can be removed through sublimation at low temperatures and low pressures, eliminating the need for solvents and high-temperature decomposition, and allowing for the formation of hollow spaces within 3D structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If solvent-based removal procedures are used to remove sacrificial materials, then the sacrificial materials can be dissolved and removed, but stiction results from capillary force during washing

Engineering Contradiction:

Improvesacrificial material removalVSAvoidstiction from capillary force

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies phase transition by using sublimation to remove sacrificial materials. The sacrificial material transitions directly from solid to vapor phase, eliminating the need for solvent washing and avoiding capillary forces that cause stiction. This is achieved by heating the structure to a temperature above the sublimation point of the sacrificial material while maintaining a vacuum or low-pressure environment.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The patent replaces the mechanical/chemical removal process (solvent washing) with a thermal process (sublimation). Instead of using solvents to dissolve and wash away sacrificial materials, the invention uses heat to directly transform the sacrificial material into vapor, which is then removed by vacuum pumping or pressure differential.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of substance

If high-temperature annealing is used to decompose sacrificial materials, then the sacrificial materials can be broken down, but decomposition residues are left behind

Engineering Contradiction:

Improvesacrificial material decompositionVSAvoiddecomposition residues

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent uses sublimation, a phase transition from solid directly to vapor, to remove sacrificial materials without decomposition. This occurs at temperatures below the decomposition point of the sacrificial material, typically in the range of 50-150°C depending on the material chosen, preventing residue formation while still enabling complete removal through vaporization.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The patent changes the temperature and pressure parameters to enable sublimation rather than decomposition. By controlling the temperature to be above the sublimation point but below the decomposition point, and maintaining low pressure to facilitate vaporization, the sacrificial material is removed cleanly without generating residues.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If sublimable materials are used as sacrificial structures, then the removal process is simplified and residues are avoided, but additional process steps for sublimation are required

Engineering Contradiction:

Improveremoval process simplicityVSAvoidprocess steps for sublimation

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent integrates the sublimation removal process with the existing manufacturing workflow by using the same vacuum chamber or heating infrastructure that may already be present in the fabrication process. The sublimation step can be combined with other thermal processing steps, reducing the need for separate dedicated removal equipment and minimizing additional process complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 method simplifies the removal process, avoids residue issues, and enables the creation of complex 3D structures with multiple hollow spaces by using phase-change materials that sublimate at low temperatures, reducing the risk of stiction and decomposition residues.

Implementation Method 1

The use of sublimable materials like cyclododecane, which can be removed through sublimation at low temperatures and low pressures

Methodology Applied

Scientific EffectSublimation: Sublimation

Implementation Method 2

The phase-change material may be deposited as a liquid, and the liquid state may fill in empty spaces and subsequently solidify to enable temporary planarization

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentUS10245820B2Forming sacrificial structures using phase-change materials that sublimate

Publication Date: 2019.04.02 XEROX CORP

AI summary

A structure can include a first layer of a polymer material and a second layer of the polymer material on the first layer, the first and second layers of the polymer material defining a hollow space that was formed by way of a temporary sacrificial structure that was made of a sublimable material.