Microfabrication And Nanomanufacturing In York: Quality Characteristics And Manufacturing Processes

Output Geometry Measurements for Cantilever-beam MEMS Accelerometer

Question:

Discuss About The Microfabrication And Nanomanufacturing York?

This research paper discusses quality characteristics of products, principle determinants of the geometry of the parts, how the components are made, key process parameters, variables used to control the business processes, variables expected to cause variation in the output, how the processes are controlled, and discussion of the advanced topics in manufacturing processes.

The key quality characteristics of the fuselage skin panel are a major consideration and the key measurements of the output geometry that should be considered include the diameter and the output constituent properties.

Some of the output geometry measurements that would be considered when dealing with cantilever-beam MEMS accelerometer include:

• Side angles
• Thickness
• Length
• Width

These properties are the function of mass and stiffness which are functions above constitutive properties and geometry. The output constitutive properties that should be considered by the customer when dealing with fuselage skin panel and cantilever-beam MEMS accelerometer include:

• Resonant frequency
• Density
• Young’s modulus

Some of the output geometry measurements that would be considered when dealing with fuselage skin panel include:

• Strength
• Thickness
• Weight
• Length
• Width

These properties are the function of mass and stiffness which are functions above constitutive properties and geometry. The output constitutive properties that should be considered by the customer when dealing with fuselage skin panel include:

• Density
• Tensile strength
• Ductility
• Brittleness
• Young’s modulus
• Tension

Cantilever-beam MEMs accelerometer

Photolithography: Chrome mask is used in this case which is a patterned wafer with photoresist and then applying Ultra Violet light to harden the resist. The resist mask is then used to pattern the oxide mask. The oxide mask is used to wet the etch silicon in the next stage. The process of lithography is used in determining the top planer dimension of the sections mainly the length and width.

Wet chemical etching: Etch with Potassium Hydroxide (KOH) for anisotropic etching of silicon is used in this case. The endpoint is then determined during the release of the cantilever, over-etching can still apply due to anisotropic. The wet etch contributes basically to the z-direction geometry of the section since angles of the sidewall are determined by the etchant used and the orientation through crystallography of the silicon substrate.

The Young’s modulus and density are functions of the bulk silicon and also independent of the process. However, since density and stiffness are also functions of the volume, and are therefore geometry, they are affected by etching chemical/time and lithography.

Sheet forming: This process is done by working the material into thin and flat pieces. Normally the sheets are rectangular and flat and they need to be designed into the shapes required according to the quality characteristics of the component. The processes that are undertaken during the sheet forming include shearing process, forming process, and finishing process.

Edge trimming: This method is applied to bonded wafer assemblies and is performed to remove a small amount of diameter on the component wafer but not the carrier wafer. This removes the narrow edge area of the component wafer where bonding voids may normally happen thus reducing the area that is most likely to suffer chipping.

Output Geometry Measurements for Fuselage Skin Panel

Rivet hole drilling: This process is done by a standard twist drill this prevents binding of the rivet in the hole. The position of the rivet holes should be centre punched and the drilling performed by the use of power drill either pneumatic or electric.

The ductility, brittleness, Young’s modulus, and tension are functions of the bulk silicon and also independent of the process. However, since density and stiffness are also functions of the volume, and are therefore geometry, they are affected by rivet hole drilling and edge trimming processes.

The process parameters used to make both the components are listed below:

Cantilever-beam MEMS accelerometer

Wet chemical etching

Equipment state: Time of KOH, temperature, concentration

Equipment properties: KOH etch rate a function of time, temperature, and concertation.

Material states: KOH product, silicon, Bulk silicon

Material properties: Mask material, the silicon type, crystallographic

Photolithography

Equipment state: Time of exposure, power density tool, UV on/off

Equipment properties: UV power density dependence on time/temperature

Material states: Cured/developed polymer, exposed polymer, the prepolymer

Material properties: Catalytic density, viscosity

Fuselage skin panel

Sheet forming

Equipment state: shape changes, thinning, cracking,

Equipment properties: Ductility, tensile strength, temperature, flexibility

Material states: Aluminium alloy, steel, titanium

Material properties: Brittleness, ductility, shear strength

Edge trimming

Equipment state: Tolerance, deep drawing, bending, cutting, bending

Equipment properties: Strasbaugh 7AF, Strasbaugh 7AA and Disco 850 back grinders.

Material states: Semiconductor substrates, SiC, Sapphire

Material properties: Sharp edge, slightly misaligned,

Rivet hole drilling

Equipment state: Rivet size, drill number, drill size,

Equipment properties: Tensile strength, size, chuck size

Material states: Semiconductor substrates, SiC, Sapphire

Material properties: Strength, texture, density, dimension

Control Variables

 Cantilever-beam MEMS accelerometer

Photolithography: Develop spic speed. Develop time, softbake temperature, softbake time, exposure time

Wet chemical etching: Etch time, chemical bath temperature, etchant concentration, the chemical etchant

Fuselage skin panel

Sheet forming: Shearing forces, required shapes, fracture,

Edge trimming: Diameter, wafer breakage, size of the edge

Rivet hole drilling: Rivet diameter, drill number, drill size

Output sensitivity to control variables

Cantilever-beam MEMS accelerometer

Photolithography: Develop spin speed, develop time, softbake temperature, softbake time, exposure time, all these affect the length and width of the oxide mask used to etch the cantilever. The Cantilever alignment to the orientation of crystallography also affects the length and width due to the sensitivity of each plane.

Wet chemical etching: Etch time, chemical bath temperature, etchant concentration, the chemical etchant, all change the thickness of the cantilever and to a cantilever of smaller degree.

Fuselage skin panel

Sheet forming: Perforation, slitting, slitting, notching, and lancing all effects the shapes of the final sheet that would be used in the manufacturing the component.

Edge trimming: Substrate edge, edge trim, wafer assemblies           

Rivet hole drilling: The rivet diameter, drill number and drill size affects the speed of the gun

Process control

Photolithography: The coupling of the mechanical kinematic with wafer flat is used for process control by ensuring that mask is aligned with the orientation of the crystal that is desired, checking the process history for the best recipe for develop time/speed, bake time/speed, and exposure time.

Manufacturing Processes: Photolithography

Wet chemical etching: Etch time, chemical bath temperature, etchant concentration, and chemical etchant.

Sheet forming: Mechanical behaviour and plastic deformation are used in the process control by ensuring that the sheet is at required dimensions according to the required component.

Edge trimming: edge trim, edge chopping and wafer breakage are used in the process control by ensuring that the edge to be trimmed has attained the required component edge.

Rivet hole drilling: The rivet diameter, drill number and drill size affects the speed of the gun

Three-dimensional refers to the process by which material is solidified or joined under computer control to form an object in three dimensions, with the addition of materials together like fusing together powder grains or liquid molecules. Three-dimensional printing is used in both additive manufacturing (AM) and rapid prototyping. The objects can be of any geometry or shape and normally are produced by the use of digital model data from a model of 3D or another source of electronic data such as Additive Manufacturing File. The following are the general principles of 3D Printing:

Modelling: The models of three-dimension can be produced by the use of photogrammetry software, digital camera, 3D scanner and a Computer Aided Design package. Printed models of 3D generated by the use of CAD result in fewer errors and can be rectified before printing, enabling verification in the object design before printing (Busnaina, 2014). The manual process of modelling of preparation of geometric data from 3D graphics of computer has some similarities with the arts like sculpting. The scanning of 3D can be defined as the process of digital data collection on the appearance and shape of an actual object, producing a model that is digital based on it.

Printing: Before a 3D model is printed from stereolithography file, it should initially be examined with errors. Majority of applications of CAD generates errors in output STL files, these errors include noise shells, face normal, and holes.  There is a step in generation of STL known as repair which fixes the errors in the actual model. After the completion, there is need of the STL file to be processed by a slicer which is a piece of software that converts the model into series of layers that are thin and generates a file of G-code which has instructions directed to a give 3D printer type.  

Fishing: Despite a resolution produced by the printer being enough for numerous applications, printing a slightly a version that is oversized of the object desired in standard resolution and then removing material with a substrate process of higher resolution may attain a greater accuracy (Evans, 2016). Some polymers like ABS enable the fishing of the surface to be improved and smoothed by the use of process of chemical vapor based on acetone or other solvents similar to it. Some techniques of additive manufacturing have the ability of utilizing numerous materials in the process of constructing sections. These methods have the ability to print colour combinations and multiple colours simultaneously and would not need painting necessarily.

Manufacturing Processes: Wet Chemical Etching

There are numerous available additive processes. The major difference between the processes are in the manner in of layer deposition and in the materials used. Every method has its own drawbacks and advantages, which is why the majority of the companies provided of polymer and powder for the material selection when building the object. The 3D printing is currently being used in sociocultural, industry, medical, manufacturing sectors which enable 3D printing to become an effective technology (Huang, 2015).

Nanomanufacturing can be defined as the manufacturing of parts top-down or bottom-up from materials that are nanoscaled on the production of nanoscaled materials which can be fluids or powders in minute stages of high precision, used in numerous technologies like etching and laser ablation. These manufacturing processes results in nanotechnology, systems, features, structures, and extreme devices that have uses in physics, aerospace engineering, molecular biology, and organic chemistry (Huang, 2015).

Nanomanufacturing facilitates the production of new products and material that are applied in lithography, electrostatic coating, medical devices, device assembly, and material removal processes. National Nanomanufacturing Network is a Nanomanufacturing program that works to expedite the transition of nanotechnologies from the research in the laboratory to manufacturing in production and it undertakes this by roadmap development, strategic workshops, and information exchange (Jackson, 2012). The organization of National Nanomanufacturing Network works to speed up the transition of nanotechnology from the research in laboratory to production manufacturing and this is attained by roadmap development, marketing strategy workshop, and information exchange.

Atomic Layer Deposition which is abbreviated as (ALD) is a technology of Nano-scale manufacturing by the use of chemical vapour deposition and bottom-up methods of manufacturing for sustainability point of view. The Atomic Layer Deposition replaced silicon oxide dielectric film with aluminium oxide dielectric film. The Atomic Layer Deposition industry is currently using semiconductor industry and promising in polymer, sensor, medical devices, fuel cells, and solar cells. The technology of Nanomanufacturing has enabled the improvement in packaging of food by improving the barrier in plastic material which enables the identification of relevant information by customers.

The performance of the traditional materials for construction namely concrete and steel has been improved through nanotechnology. The reinforcement of concrete with metal oxide nanoparticles increases the strength minimizes the permeability of the construction material. The Property of Young’s modulus and tensile strength of Nanocarbon additives like Carbon nanofibers and Carbon nanotubes has led to the creation of materials that are porous and denser (Lipson, 2011).

Nanomanufacturing is normally divided into two groups namely bottom-up and top-down approaches. Nanoscale Offset Printing System which is abbreviated as NanoOps is an example of such technologies which is a form of directed assembly that is more economical and faster than outdated 3D nanosystem printing. A template that is etched with nanowires is dipped in a solution with nanoparticles which acts as the ink for the press. Nanoparticles adhere to the template due to the application of electricity to the solution. A template joined with nanoparticles may then be removed from the solution and pressed onto any choice of material (Lipson, 2011). 

The transition of nanotechnology from the demonstrations in the laboratory to the manufacturing in the industries has led to numerous challenges such as ethical and social impacts to the environment, difficulty in maintaining quality of nano-system and nano-scale properties during high volume and high rate production, difficulty in testing reliability and determining ways of controlling defects, difficulty in controlling accuracy of nanostructure assembly, and also difficulty in developing techniques of production that are economical and produce yields that are viable.

References

Busnaina, A. (2014). Nanomanufacturing Handbook. Colorado: management.

Evans, B. (2016). Practical 3D Printers: The Science and Art of 3D Printing. Michigan: Apress.

Huang, W. (2015). Nano papers: From Nanochemistry and Nanomanufacturing to Advanced Applications. California: Elsevier Science.

Jackson, M. (2012). Microfabrication and Nanomanufacturing. New York: CRC Press.

Kelly, J. (2013). 3D Printing: Build Your Own 3D Printer and Print Your Own 3D Objects. London: Que Publishing.

Lipson, H. (2011). Fabricated: The New World of 3D Printing. New York: John Wiley & Sons.