CO2 Composite Spray Technology for Probe Card Cleaning
David Jackson Cool Clean Technologies Contributors Roger Caldwell, Vitesse Semiconductor Andy Hoyle, Vitesse Semiconductor
ResistiveResistive SurfaceSurface ContaminationContamination
• Metal Oxides (Sn, Pb, Al) • Passivation • Silicon Nitride • Polymers (plasticizers/fibers) • Lapping Compounds • Adhesive Residues • Outgas Compounds • Metals (solder, Al) • Human Contaminants • Cleaning Residues • Solder Flux
June 8 to 11, 2008 IEEE SW Test Workshop 2 CleaningCleaning andand CleanlinessCleanliness IssuesIssues
Contamination tends to Contaminations: bond/adhere in cohesive • A mix of transferred metals, organics, layers… inorganics, ionics and adsorbed films • Thin and thick layers/films
Contact Surfaces: • Surface area (contact zone) changes over time • Small/complex topography (curved, pointed, crowned)
Cleaning Processes: • Incompatibilities (damage/efficacy) Contamination generates • Variability/Quality more contamination. • Long cleaning times (manual methods)
June 8 to 11, 2008 IEEE SW Test Workshop 3 CleaningCleaning MethodsMethods (probe/socket)(probe/socket) Method M T C Manual 1. WC Plate x 9 Direct Contact 2. Lapping Films x 9 Low Capital 9 High Labor 3. Metal/Polymer Brush x 4. Ceramic Block x 5. Polymer Sheets x 6. Microabrasive Spray x 7. Camel Hair Brushing x 8. IPA Wet Brushing x x Automated 9. Weak Acid Cleaning x x x 9 Non-Contact 9 High Capital 10. Ultrasonic Cleaning x x x 9 Low Labor 11. Plasma Cleaning x x x M – Mechanical Energy T – Thermal Energy C - Chemical Energy June 8 to 11, 2008 IEEE SW Test Workshop 4
CleaningCleaning ProcessProcess ChallengeChallenge
Applying insufficient cleaning
energy increases cleaning time. Applying excessive cleaning 2
energy is wasteful, may increase 1
cleaning time and/or may damage 0 CONTAMINATION 1 surfaces. 0
C LE E A IM N T IN G G N E I N N E A R LE G C Y 1 0 9 Adapted from “Theory of Cleaning”, B.N.Ellis, June 8 to 11, 2008 IEEE SW Test Workshop Circuit World, Vol.12 No.1, 1985 5 CleaningCleaning ProcessProcess ChallengeChallenge Cleaning Energy >= ∑Contaminant-Surface Adhesion Energies
Method 3 Method 4
Method 8 Method 1
Method 5
Method 9 Method 10 Method 2
Method 7 Method 6 Best Practice Combination of Optimal
June 8 to 11, 2008 Chemical-MechanicalIEEE SW Test Workshop Effects 6 CleaningCleaning ProcessProcess ChallengeChallenge
The most desirable cleaning process:
9 Non-destructive (contact surface/peripheral surfaces) 9 Minimal or no human contact 9 Robust (in terms of energy control) 9 Both mechanical and chemical cleaning actions 9 Ability to clean dense and complex surfaces 9 Fast (less cleaning labor/time) 9 Low cost-per-clean 9 Minimal or no cleaning agent by-products 9 Acceptable ROI
June 8 to 11, 2008 IEEE SW Test Workshop 7 COCO2 CleaningCleaning TechnologyTechnology
CO2 technology has been used to produce consistently
clean surfaces for high-tech products such as spacecraft devices, optical devices, sensors, lasers, disk drives, air bags, medical devices and probe cards… Treatment Schemes • Composite CO2 Spray *
• Immersion Solvent (Liquid) • Extraction Solvent (Supercritical) • Atmospheric Plasma * • Low Pressure Plasma • UV-CO2 Treatment • Plasma-CO2 * Hybrid Processes 2 • Laser-CO * • Microabrasive-CO2 * * - Probe cleaning candidates June 8 to 11, 2008 IEEE SW Test Workshop 8 COCO2 isis AbundantAbundant
South Pole - Mars
A recycled by-product from industrial and natural sources such as refineries, CaCO3 wells,
and bakeries. A recyclable and renewable resource.
Major commercial uses include beverage carbonation, fire extinguishing and welding.
June 8 to 11, 2008 IEEE SW Test Workshop 9 COCO2 isis SafeSafe
Ozone Depleting OSHA Solvent Potential PEL VOC (ODP) (ppm) Carbon Dioxide None 5,000 No Isopropyl Alcohol ~0 400 Yes Acetone ~0 1000 No Trichloroethylene ~0 50 Yes 1,1,1-Trichloroethane 0.15 350 Yes n-Propyl Bromide ~0 100 Yes
CO2 is non-toxic, non-flammable and non-corrosive.
2 Recycled CO is exempt from the EPA Global
Warming legislation. June 8 to 11, 2008 IEEE SW Test Workshop 10 COCO2 isis InexpensiveInexpensive
Bulk Price Range Solvent $/kg Carbon Dioxide 0.10 - 0.25 Acetone 0.44 - 0.49 Isopropyl Alcohol 0.75 - 0.88 Methylene Chloride 0.80 - 1.25 1,1,1-Trichloroethane 1.25 - 2.00 n-Propyl Bromide 3.00 - 5.00
Just pennies of CO2 are used in composite spray
formulations for a cleaning operation…
June 8 to 11, 2008 IEEE SW Test Workshop 11 COCO2 CleaningCleaning AgentsAgents CLEANING PROCESS 4 Extraction PHASE DIAGRAM
FOR CO2 SCF Immersion 73 ATM SOLID LIQUID 2 Spray GAS
H.P. PRESSURE 5b 3 PLASMA 1 1 ATM L.P. 5a PLASMA
-80 C TEMPERATURE 32 C
June 8 to 11, 2008 IEEE SW Test Workshop 12 COCO2 SolventSolvent PropertiesProperties Carbon Dioxide Acetone DENSITY Solid Liquid Supercritical g/ml 1.6 0.8 0.5 0.8
VISCOSITY - 0.07 0.03 0.32 mN-s/m2
SURFACE TENSION 5-10 5 0 24 dynes/cm
SOLUBILITY 22 22 14 20 MPa1/2
June 8 to 11, 2008 IEEE SW Test Workshop 13 SolidSolid CarbonCarbon DioxideDioxide
SEM Photomicrograph • Structure - molecular crystal, angular, octahedron • Solvency – hydrocarbon-like, 22 MPa1/2 • Impact Phenomenon – ablation and phase change (solid->gas, solid->liquid- >gas) • Chemistry – can be modified with 1 μm plasmas, liquids, solids, vapor-phase additives • Compressibility - incompressible 3 • Density - 1.6 g/cm • Hardness – 0.3 Hm (8 Hv) • Particle Size – < 0.5 microns to > 500 microns, range adjustable (coarse/fine) • Impact Stress - up to 60 MPa (8,700 psi) June 8 to 11, 2008 IEEE SW Test Workshop 14 ConventionalConventional SnowSnow CleaningCleaning
9 CO2 “snow” particles are too small and can’t deliver the shear stress required to dislodge resistive contaminants.
9 CO2 snow sprays are too dense and cold (- 80 F), which tends to shield/freeze surface contamination (“Igloo Effect”).
9 CO2 snow sprays discharge at a high pressure (800+ psi) that can damage structures at close proximity (needed for cleaning effectiveness with small particles).
CO2 composite spray technology is better suited to the contact cleaning task…Why ? June 8 to 11, 2008 IEEE SW Test Workshop 15 FirstFirst……VariableVariable ParticleParticle SizeSize andand DensityDensity
Adjustable compositions of lean (high freq. impacts) energetic CO2 particles (size control) and heated propellant gas…at low spray pressures (10 -120 psi).
CO2 COMPOSITE SPRAY CLEANING ENERGY ∆v Shaved Ice and F = m x Pellets ∆t (100 - 500 MPa)
COARSE CO2 Composite Sprays Impact ! 500 (0.01 - 60 MPa)
MEDIUM Control Parameters
100 CO2 Particle Size CO2 Particle Density FINE Propellant Pressure (microns) Snow Propellant Temperature 10 Sprays (0.01 - 2 MPa) PARTICLE RANGE ULTRAFINE 1
0.1 1 10 60 IMPACT SHEAR STRESS (MPa)
June 8 to 11, 2008 IEEE SW Test Workshop 16 SecondSecond……SpraySpray CompositionComposition ControlControl Additive(s) Gas (Chemical/ (Propulsion/ Physical) Heating)
Chemical Thermal Mechanical Particle Size Chemistry
CO2 Spray Density Temperature
CO2 Spray Cleaning Parameters Pressure Spray Pressure/Temp: 40 psi / 120 C Cleaning Time/Distance: 30 seconds / 1.5 inches Chemistry: CDA, Fine CO2 Particles Distance/Angle Time June 8 to 11, 2008 IEEE SW Test Workshop 17 ThirdThird……ProcessProcess EnhancementEnhancement ToolTool
CO2 composite sprays easily
adapt to and augment an existing probe maintenance program to increase overall cleaning process efficiency and effectiveness ….
Existing Cleaning and Inspection Process
Composite sprays are additive without being mechanically destructive (energy control)…
June 8 to 11, 2008 IEEE SW Test Workshop 18 COCO2 CompositeComposite SpraySpray TechnologyTechnology
Hybrid
Coanda
Coaxial
• Capillary condensation for particle size control • Micro-metered mass flow for precise spray density control • Clean hot propellant gas for pressure and temperature control • Coaxial and Coanda composite spray nozzles • Chemical co-solvents easily employed • Hybrid CO2 composite spray treatments - Microabrasives, Laser, Atmospheric Plasma, Chemical Adjuncts, Brush
June 8 to 11, 2008 IEEE SW Test Workshop 19 COCO2 CompositeComposite SpraySpray TechnologyTechnology
Lean Composite CO2 Sprays, used in cooperation.
June 8 to 11, 2008 IEEE SW Test Workshop 20 COCO2 CompositeComposite SpraySpray TechnologyTechnology
SNOW SPRAYS (Conventional) Convergent-Divergent FINE SOLIDS Nozzle ENTRAINED Liquid IN COLD CO2 HIGH VELOCITY CO2 GAS COMPOSITE SPRAYS Liquid Coaxial or Coanda CO2 Mixing Nozzle SIZE-CONTROLLED Hot SOLIDS ENTRAINED CDA IN HEATED, Additive(s) VELOCITY- CONTROLLED
June 8 to 11, 2008 IEEE SW Test Workshop AIR 21 COCO2 CompositeComposite SpraySpray TechnologyTechnology
Mechanical and Tribo-Chemical Cleaning Actions
CO2 composite spray cleaning process
effectiveness and efficiency is controlled by:
9 Particle velocity 9 Particle mass/size 9 Spray chemistry 9 Particle hardness (fine Æ coarse) 9 Particle shape (angular is better (stress conc.)) 9 Impact frequency 9 Spray distance 9 Time
June 8 to 11, 2008 IEEE SW Test Workshop 22 COCO2 CompositeComposite SpraySpray TechnologyTechnology
Peak Impact Stress v. Propellant Pressure
65 120 psi 60 Increasing propellant pressure and working closer to the surface increases impact energy. 55
50 206 kPa 45 414 kPa 483 kPa 40 621 kPa 35 827 kPa Impact Stress/MPa 30 30 psi Coanda M 25 100 Deg. C (378 K)
20 0 5 10 15 20 25 30 35 Distance/cm
CO2 composite spray cleaning energy varies with pressure, temperature, particle size and additive energy…
June 8 to 11, 2008 IEEE SW Test Workshop 23 COCO2 CompositeComposite SpraySpray TechnologyTechnology
Surface Impact
Adjustable Particle Size,Velocity, and Spray Density
Lean sprays create (2-Phase Flow) more energetic impacts/time… CO2
AIR
Metal Oxides, Particles, Fibers, 75-300 m/s Thin Films
DIRTY CONTACT SURFACE
June 8 to 11, 2008 IEEE SW Test Workshop 24 COCO2 CompositeComposite SpraySpray TechnologyTechnology
Contamination Removal
Contaminants Filtered from Air Scrubs complex surfaces…
Mechanical Ablation Chemical Solubility
CLEAN CONTACT SURFACE
June 8 to 11, 2008 IEEE SW Test Workshop 25 COCO2 CompositeComposite SpraySpray CleaningCleaning SystemSystem
Several CO2 composite spray
cleaning methods and processes under development for probe cards (and test sockets)…
Manual – Automated - Hybrids
June 8 to 11, 2008 IEEE SW Test Workshop 26 CleaningCleaning ProcessProcess DevelopmentDevelopment
R&D System at customer site
June 8 to 11, 2008 IEEE SW Test Workshop 27 CleaningCleaning ProcessProcess DevelopmentDevelopment
Goal: Minimize or eliminate direct contact cleaning.
Clean-during-Inspection
CO2 Manual Pretreatment Mechanical (no additives)
As much as As little as possible possible
June 8 to 11, 2008 IEEE SW Test Workshop 28 CleaningCleaning ProcessProcess DevelopmentDevelopment For a given spray cleaning composition: 1. Scan rate 2. Distance 3. Spray angle y 4. Time x
z
June 8 to 11, 2008 IEEE SW Test Workshop 29 CleaningCleaning ProcessProcess DevelopmentDevelopment What should be cleaned ? Best Practice: Contacts plus Peripheral Surfaces
Contamination migrates through ES-Fields, thermal gradients, physical transfer modes…
Not cleaning the entire surface creates the potential for cross-contamination… June 8 to 11, 2008 IEEE SW Test Workshop 30 CleaningCleaning ProcessProcess DevelopmentDevelopment Pre-Cleaning 1 Pre-Cleaning 2 CO2 Composite Spray Cleaning Post Cleaning 70.0000
60.0000
Pad 90 50.0000 (outlier)
40.0000
Ohms 30 30.0000
20.0000 15 second Spray Treatment 10.0000 1.5
0.0000 Pad
June 8 to 11, 2008 IEEE SW Test Workshop 31 CleaningCleaning ProcessProcess DevelopmentDevelopment
Pad Cres
5
4 Cres Preclean 1 3 Cres Preclean 2
Ohms 2 CO2 Composite Spray 1 82% reduction in pad 0 1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 Cres failures/ 15 sec spray treatment. Contact Pad 33Æ6 Outlier data (Pad 90) removed from data set
June 8 to 11, 2008 IEEE SW Test Workshop 32 CleaningCleaning ProcessProcess DevelopmentDevelopment
Average Cres Reduction
28% reduction/15 sec. 2.0000 Cres Preclean 1 1.5000 Cres Preclean 2 Ohms 1.0000
0.5000 15 second Spray Treatment 0.0000
Outlier data (Pad 90) removed from data set.
June 8 to 11, 2008 IEEE SW Test Workshop 33 CleaningCleaning ActionAction Before After
Metal Oxides/Solder Cleaning Spray Parameters: Spray Pressure/Temp: 80 psi/120 C Cleaning Time/Distance: 1 minute/1 inch Chemistry: CDA, Coarse CO2 Particles June 8 to 11, 2008 IEEE SW Test Workshop 34
CleaningCleaning ActionAction Before
After
Aluminum/Al203
Cleaning Spray Parameters: Spray Pressure/Temp: 70 psi/120 C Cleaning Time/Distance: 3 minutes/2 inches (robotic process) Chemistry: CDA, Fine CO2 Particles June 8 to 11, 2008 IEEE SW Test Workshop 35
CleaningCleaning ActionAction
Metal Oxides and Solder Flux
Cleaning Spray Parameters: Spray Pressure/Temp: 40 psi/120 C Cleaning Time/Distance: 30 seconds/1.5 inches Chemistry: CDA, Fine CO2 Particles June 8 to 11, 2008 IEEE SW Test Workshop 36
CleaningCleaning CostCost ReductionReduction
Existing Process: • Easy to get lost under scope
• Surface contamination remains in complex topography (crevices)
• Potential physical damage to surfaces with brush
• Time intensive
June 8 to 11, 2008 IEEE SW Test Workshop 37 CleaningCleaning CostCost ReductionReduction
New Process:
In combination with CO2 pretreatment: 9 Significant reduction in maintenance labor 9 Cleaner surfaces…faster 9 Much less direct contact 9 Much less physical damage
June 8 to 11, 2008 IEEE SW Test Workshop 38 WrapWrap--upup
• Composite CO2 sprays are fully adjustable and provide quick, clean, and non-
destructive contact cleaning. • Worker- and equipment-safe cleaning process.
• Adaptable to existing cleaning processes. Minimizes manual cleaning, potential to replace mechanical contact treatments.
• Low cost-per-clean with a significant contact maintenance labor (time) reduction potential.
June 8 to 11, 2008 IEEE SW Test Workshop 39 QuestionsQuestions ??
For more information:
David Jackson [email protected] 661-803-0546 http://www.purco2.com
June 8 to 11, 2008 IEEE SW Test Workshop 40