FORMING SACRIFICIAL STRUCTURES USING PHASE-CHANGE MATERIALS THAT SUBLIMATE
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.
The disclosed technology relates generally to the field of forming sacrificial structures and, more particularly, to forming sacrificial structures using phase-change materials that sublimate.
BACKGROUNDIn today's layer-by-layer printing techniques for forming three-dimensional (3D) structures, sacrificial materials are generally needed to form temporary support structures that are later removed to leave behind voids or channels. Typical sacrificial materials include polymers or waxes that are dissolvable by solvents or can be decomposed by high-temperature annealing. However, such removal procedures can disadvantageously cause problems arising from stiction (e.g., static friction that needs to be overcome to enable relative motion of stationary objects in contact) resulting from capillary force during washing. These removal procedures may also undesirably cause decomposition residues to be left behind.
SUMMARYAccording to aspects illustrated herein, there is provided a structure comprising 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 such as cyclododecane and then removed. This process may be repeated any of a number of times, e.g., to build up layered structures having multiple hollow spaces.
Embodiments of the disclosed technology generally pertain to the use of a sacrificial material that can be removed by sublimation, accelerated by heat and/or a low pressure environment. Such embodiments generally do not rely on the use of solvents to wash off the sacrificial materials, thus simplifying the removal process as compared to the decomposition of polymers that requires high temperature burning, for example,
Certain embodiments of the disclosed technology generally include the use of materials that can be sublimated at low temperature (e.g., less than 160 degrees C.) as the sacrificial structures. Use of such materials may advantageously avoid the use of a solvent or high temperature decomposition during the removal process. 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.
Certain embodiments of the disclosed technology may include the use of cyclododecane, which is a hydrocarbon having a melting point around 58-60 degrees C. and high vapor pressure that allows sublimation thereof at low temperature. The phase-change material may be heated to its liquid state for deposition, and then solidify upon contacting a surface below its melting point.
As cyclododecane has high vapor pressure (e.g., approximately 10 Pa), it may typically be sublimated at room temperature, though generally at slow rate. In certain embodiments, material removal may be accelerated by heating the structure in a low vacuum oven (e.g., 1 millitorr or mTorr) at a certain temperature (e.g., approximately 55 degrees C.). In such embodiments, the sacrificial cyclododecane may be sublimated within minutes, depending on the volume of materials.
The entire structure illustrated by
The sacrificial ink used in the example illustrated by
At 602, a first layer of a polymer material, such as the ultraviolet (UV)-curable polymer material 102 illustrated by
At 604, a sublimable material, such as the sacrificial material 204 illustrated by
At 606, a second layer of the polymer material, such as the UV-curable polymer material 306 illustrated by
At 608, the sublimable material may be removed, e.g., by a sublimation process, to form a hollow space, such as the channel 408 illustrated by
Materials having different vapor pressure may be chosen to form sacrificial structures that are sequentially removed. For example, if a certain structural part is to be released before another, the first part may be patterned by a sacrificial material having a certain vapor pressure and the second part to be released may be patterned using a sacrificial material having a vapor pressure that is lower than that of the first sacrificial material.
In addition to patterning a sacrificial material in a layer-by-layer manner, the material may also be deposited into a well structure in order to fill in the empty space and hence provide temporary structural support.
It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
Claims
1. A structure, comprising:
- 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.
2. The structure of claim 1, wherein the sublimable material includes cyclododecane and/or other phase-change composites.
3. The structure of claim 1, wherein the sacrificial structure has been removed by way of sublimation.
4. The structure of claim 3, wherein the sublimation was performed at a pressure of approximately 1 millitorr.
5. The structure of claim 3, wherein the sublimation was performed at a temperature less than 160 degrees C.
6. The structure of claim 5, wherein the temperature was approximately 55 degrees C.
7. The structure of claim 1, wherein the polymer material is an ultraviolet-curable polymer material.
8. The structure of claim 1, wherein the hollow space is a cavity or a channel.
9. The structure of claim 1, the first and second layers of the polymer material defining another hollow space that was formed by way of another temporary sacrificial structure that was made of the sublimable material.
10. The structure of claim 1, further comprising a third layer of the polymer material on the second layer, the third and second layers of the polymer material defining another hollow space that was formed by way of another temporary sacrificial structure that was made of the sublimable material.
11. A method, comprising:
- depositing a first layer of a polymer material;
- depositing a first amount of sublimable material on the first layer of the polymer material to form a first sacrificial structure;
- depositing a second layer of the polymer material on the first amount of sublimable material and first layer of the polymer material; and
- removing the sublimable material to form a first hollow space defined by the first and second layers of the polymer material.
12. The method of claim 11, wherein the removing includes performing sublimation.
13. The method of claim 12, wherein the sublimation includes heating at a certain temperature and at a certain pressure.
14. The method of claim 13, wherein the certain pressure is approximately 1 millitorr.
15. The method of claim 13, wherein the certain temperature is less than 160 degrees C.
16. The method of claim 15, wherein the certain temperature is approximately 55 degrees C.
17. The method of claim 11, wherein the sublimable material includes cyclododecane and/or other phase-change composites.
18. The method of claim 11, wherein the hollow space is a cavity or a channel.
19. The method of claim 11, further comprising to build multiple layered structures. depositing a second amount of sublimable material on the first layer of the polymer material to form a second sacrificial structure;
- depositing a third layer of the polymer material on the second amount of sublimable material and first layer of the polymer material; and
- removing the sublimable material to form a second hollow space defined by the first and third layers of the polymer material.
20. The method of claim 11, further comprising to build multiple layered structures.
- depositing a second amount of sublimable material on the second layer of the polymer material to form a second sacrificial structure;
- depositing a third layer of the polymer material on the second amount of sublimable material and second layer of the polymer material; and
- removing the second amount of sublimable material to form a second hollow space defined by the second and third layers of the polymer material.
Type: Application
Filed: Dec 11, 2014
Publication Date: Jun 16, 2016
Inventors: Tse Nga Ng (Sunnyvale, CA), Bing R. Hsieh (Pleasanton, CA), Steven E. Ready (Los Altos, CA)
Application Number: 14/567,010