Ion Mobility Spectrometer in LTCC

1
Ion Mobility Spectrometer in LTCC

• Don Plumlee, Amy Moll
• Boise State University
• M. Tam, P. Dwivedi, H.H. Hill Jr
• Washington State University

2
Ground-Rules

• Mechanical Engineer - Aerospace background
• C-MEMS MESO-Electrical Mechanical Systems

3
Overview

• Why LTCC?
• BSU Design/Fabrication Process
• EPA Sensor Project
• IMS Design
• IMS Fabrication
• Test Article Prototype
• Device Images
• Acknowledgements

4
Why we use LTCC?

• Process
• Low Capital Investment
• Quick Prototyping
• Electrical
• Integrated Passive Components
• High circuit density (3D Structure)
• Thermal
• High ambient temperature resistance
• Close match to semiconductor TCE
• Mechanical
• Machineable (Drill, Cut, Punch) in Green State.
• High Mechanical Strength after firing
• Multi-layer Structure
• Hermetically-sealed Package

5
BSU Design Process
Milled Substrate
DXF to HPGL Milling Path
Solid Works Drawings (DXF)
DXF to Printer
Solid Works Part
Screen Pattern
6
BSU Fabrication Process

• Cut Blanks
• First Routing Process
• Use CNC milling machine
• Route vias, registration holes and internal
  cavities
• Fill vias
• Print Conductor/Resistor Patterns
• Collate and Laminate
• Second routing process
• Initial substrate is segmented in the un-fired
  state
• Final Assembly
• Segments aligned
• Segments bonded using Pressure Sensitive Adhesive
• Prevents cavity collapse during lamination
• Co-Fire device

7
C-MEMS Laboratory at BSU
8
CNC Milling Machine
Spindle
Ceramic Vacuum Chuck
9
EPA Sensor Project

• Objective Accurate Time/Space tracking of
  chemical migration in groundwater
• Collaboration between Boise State University
  (BSU) and Washington State University (WSU)
• A sensor is inserted into the soil using ground
  penetrometer.
• The sensor analyzes groundwater chemical
  concentrations.
• Data is broadcast and collected from an array of
  sensors in real-time.

10
Ion Mobility Spectrometer (IMS)

• Detection Accuracy
• Distinguish different species
• Sensitive to ppm range
• Fast
• Small Size
• Fits in insertion tube
• Axial construction
• Robust

11
IMS Schematic
12
IMS Design Requirements

• Constant Electric Field (500V/cm)
• Minimize Radial Diffusion
• Self-Contained Device
• Protection
• Hermetic
• Reliable
• Preliminary Device Dimensions (WSU)
• 4 cm OD maximum
• 2 cm ID preferred
• 12 cm length of Drift Tube
• Operational Temperature
• gt 100ºC

Ion Perturbation in Tube
13
IMS Model Assembly
14
Aperture/Collector Segment
15
Drift Tube Segment
16
Tyndall Gate Segment
17
Ionization Tube Segment
18
Segmented Manufacturing Process
Drift Tube Example
Stack/ Laminate
Route Perimeter
Assemble Segments
PSA Bond
19
Development Direction

• Initial Design Prototype
• 800 layers
• Unproven Process
• Large Material Investment per Device
• Test Article Prototype
• 66 layer construction
• Prove Overall Process
• Smaller Size
• 28mm OD
• 4mm ID
• Reduced Material Investment (11 base sheets)

20
Test Article Prototype - Fabrication
Gold-Sputtered Gate
Tyndall Gate Segment
Segments
Final Assembly
21
Test Article Prototype - Completed
Separation during firing
22
Preliminary Results

• Conductivity achieved to
• Co-Fired Screen Gates
• First Drift Tube Ring
• Separation caused open circuit in Drift Tube
• Dual routing steps successful
• PSA low-pressure bonding partially successful
• 66 layers fired with one separation

23
Future Goals

• IMS Prototype
• Complete 2nd Test Article Prototype
• Test IMS at WSU Analytical Chemistry Laboratory
  (target 10 ppm toluene)
• Optimize IMS Design
• Complete Thesis
• Optimize Fabrication Process
• Add New Fabrication Techniques
• Pursue additional LTCC devices and applications
  using the C-MEMS process.

24
BSU C-MEMS Projects

• Current Work
• Capacitive Pressure Sensor
• Electro-Chemical Cell
• Ion Mobility Spectrometer (IMS)
• Future Work
• Power Scavengers
• Meso-Scale Nozzles (5N Thrust)

25
Acknowledgements

• IMAPS Sidney J. Stein Educational Foundation
  Grant (2002-2003)
• Environmental Protection Agency (EPA)
• DuPont Material Donations
• Agilent Equipment Donations