VISVESVARAYA NATIONAL INSTITUTE OF TECHNOLOGY NAGPUR

DEPARTMENT OF MECHANICAL ENGINEERING

SEMINAR ON

“ ”

GUIDED BY:PROF. Y. M. PURICAD/CAD ENGG.

PREPARED BY: BHUPESH D. SARODE CAD/CAM ENGG.FIRST SEM

2012-13

Scope Of Presentation What is MicromachiningTypes of Machines in MicromachiningVarious Micro Machines

Etching Process, Bulk Micromachining,Surface Micromachining,LIGA ProcessEDM

Application

MICRO-MACHINING

• Micromachining is the basic technology for fabrication of micro-components of size in the range of 1 to 500 micrometers

TYPES OF MACHINE IN MICROMACHINING

Tool based

Solid Tool Image ToolIsotropic

Process

Micromachining

Mask based

Anisotropic

Process

Wet etching

Ion beam

machining

LIGA

Laser beam

machining

Laser beam

Electron beam

Ion beam

Excimer laser

Wet etching

Plasma etching

Electroforming

Cutting

Grinding

Milling

EDM

ECM

Punching

Pressing

Injection

Micro-Machining Processes

5

Micro-Machining

ETCHINGBulk

Micro-

Machining

Surface

Micro-

Machining

LIGA EDM

ETCHING PROCESS

Etching process consists of three steps:

Mass transport of reactants (through a boundary layer)

to the surface to be etched

Reaction between reactants and the film(s) to be

etched at the surface

Mass transport of reaction products from the surface

through the boundary layer

ETCHING PROCESS

• Isotropic vs. Anisotropic

• Isotropic– etch rate is same in all directions

• Anisotropic– etch rate is orientation dependent

• Dry vs. Wet

• Dry– uses gas-phase process

• Wet– uses liquid-phase process

WET ETCHING PROCESS DESCRIPTION

The wet etching process involves :

Performed in an immersion tank

Wafers in wafer carrier are lowered into etchant solution

Wafers remain in solution for specified amount of time

.referred to as etch duration

Wafer carrier is removed from solution

Wafers are rinsed in deionized water

Wafers are dried

BULK MICROMACHINING

• Process for producing 3D MEMS structures –older process

• Uses anisotropic etching of single crystal silicon

Example: silicon cantilever beam for atomic force microscope

Dopant Diffusion

Masking

Anisotropic Etching

BULK MICROMACHINING

• Newer process for producing MEMS structures

• Uses etching techniques to pattern micro-scale structures from polycrystalline (poly) silicon, or metal alloys

• Examples: accelerometers, pressure sensors, micro gears and transmissions,micro mirrors etc.

SURFACE MICROMACHINING

SURFACE MICROMACHINING

(a) DEPOSITION OF

POLYSILICON;

(b) ETCHING OF

POLYSILICON;

(c) SELECTIVE WET

ETCHING OF PSG,

LEAVING THE

SILICON

SUBSTRATE AND

DEPOSITED

POLYSILICON

UNAFFECTED

GERMANACRONYM

LITHOGRAPHIE -----------------LITHOGRAPHY

GALVANOFORMUNG -------------- ELECTROFORMING

ABFORMNG -----------------------------MOLDING

LIGA

LIGA

X-ray Irradiation

Resist Development

Electroforming

Resist Removal

VIDEO ON LIGA

workpiece+anode

-cathode

(a) Tool and workpiece immersed in

dielectric liquid.

(b) A spark is generated between tool and

workpiece.

(c) The high temperature causes the melting

and vaporization of electrodes.

(d) At the end of the pulse, the molten

material is ejected from surface, leaving a

shallow crater.

electrode

Material Removal Mechanism of EDM

Micro EDM Equipment

VIDEO ON EDM

1. Machine any conductive materials.

2. Single or medium size production.

3. Slots and Arbitrary 3D micro molds.

Capabilities of Micro EDM

MICRO-LATHE

MICRO-FACTORY

APPLICATIONS

IC Packages with Micro Devices like computer processors

Fuel Injection Nozzle for Automobiles

Biotechnology for micro-needles, drug delivery systems

Medical Applications for tablet camera

Multifunctional Compact Devices like mobile, data storage device,

Micro sensors, actuators, etc

THANK YOU