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Slide 1ITC Board Test Tutorial Part 1, Last revised: September, 2003
Agenda
Introduction- Definitions, Defect levels, etc
Electrical test - MDA, ICT, FTP, & FT
Inspection - MVI, SPI, AOI, & AXI
Other test issues - DFT, DFM, Economics
Slide 2ITC Board Test Tutorial Part 1, Last revised: September, 2003
Inspection - Topics
IPC 610 Electronic Acceptability Standard
Manual Visual Inspection (MVI)
Solder Paste Inspection (SPI)
Automated Optical Inspection (AOI)
Automated X-ray Inspection (AXI)
Slide 3ITC Board Test Tutorial Part 1, Last revised: September, 2003
IPC-A-610C
IPC-A-610C illustrates industry-accepted workmanship criteria for electronics assemblies through full-color photographs and illustrations.
The topics include component orientation and soldering criteria for through-hole, SMT and discrete wiring assemblies, etc.
Now available in Chinese, Finnish, French, Portuguese, Spanish and Swedish.Translation work is continuing for other languages
372 pages, released January 2000
Additional information: http://www.ipc.org
Acceptability of Electronic Assemblies
Slide 4ITC Board Test Tutorial Part 1, Last revised: September, 2003
IPC-A-610C
Three classes:
Class 1 - General Electronic ProductsTypically consumer products, some computer and computer peripherals of consumer type
Class 2 - Dedicated Service Electronic ProductsTypically Communication equipment, sophisticated business machines, and instruments
Class 3 - High Performance Electronic ProductsTypically Medical life support, Aero-space and military equipment
The contract between the CM and the OEM may say that quality levels should be according to IPC-A-610 Class 2.
Slide 5ITC Board Test Tutorial Part 1, Last revised: September, 2003
Slide 6ITC Board Test Tutorial Part 1, Last revised: September, 2003
Slide 7ITC Board Test Tutorial Part 1, Last revised: September, 2003
IPC-A-610C
AOI and AXI systems do NOT measure directly to the IPC-A-610C
Some cases it is very clearMissing componentsOpensBridging
Some cases is not so clearInsufficientMisalignmentVoidsSolder balls
In most of those cases the AOI or AXI calls the joints and the Repair Operator makes the call
In some cases AOI and/or AXI does not call IPC-A-610C violations
Slide 8ITC Board Test Tutorial Part 1, Last revised: September, 2003
Inspection - Topics
IPC 610 Electronic Acceptability Standard
Manual Visual Inspection (MVI)
Solder Paste Inspection (SPI)
Automated Optical Inspection (AOI)
Automated X-ray Inspection (AXI)
Slide 9ITC Board Test Tutorial Part 1, Last revised: September, 2003
MVI and MXI
Manual Visual InspectionPros and Cons
Manual X-ray InspectionPros and Cons
Slide 10ITC Board Test Tutorial Part 1, Last revised: September, 2003
Manual Visual Inspection (MVI)
• Naked eye
• Magnifying glasses
• Microscope
Slide 11ITC Board Test Tutorial Part 1, Last revised: September, 2003
Manual Visual Inspection (MVI)
Inexpensive, easy to implement, flexible,finding defects
Advantages:
Slide 12ITC Board Test Tutorial Part 1, Last revised: September, 2003
Manual Visual Inspection (MVI)
1Inspector
2Inspectors
3Inspectors
4Inspectors
Green: % of AgreementBlue: % of Disagreement
6%12%28%44%
How Often Do Different Visual Inspectors Agree?
AT&T study
Slide 13ITC Board Test Tutorial Part 1, Last revised: September, 2003
Hidden Solder Joints
BGA RF shields
These Solder Joints Can Not Be Inspected Visually
Slide 14ITC Board Test Tutorial Part 1, Last revised: September, 2003
Manual Visual Inspection (MVI)
Disadvantages: SubjectiveInconsistentHard to inspect small componentsTypically no process monitoringCan not see hidden joints
Advantages: InexpensiveEasy to implementFlexible
Slide 15ITC Board Test Tutorial Part 1, Last revised: September, 2003
Can see hidden jointsCan tilt the board in differentdirections
Manual X-ray
Slide 16ITC Board Test Tutorial Part 1, Last revised: September, 2003
Can see hidden jointsCan tilt the board in differentdirections
Manual X-ray
Not always that easy
Can you see the open BGA?
Slide 17ITC Board Test Tutorial Part 1, Last revised: September, 2003
Manual X-ray Inspection (MXI)
Disadvantages: SlowTypically no process monitoringCan not be in-line
Advantages: Relative InexpensiveCan see hidden jointsGood for failure analysis anddiagnostic help
Slide 18ITC Board Test Tutorial Part 1, Last revised: September, 2003
What is Driving Automated Inspection?
• Continuing miniaturization• Higher volumes• Increasing complexity• Decreasing quality
Slide 19ITC Board Test Tutorial Part 1, Last revised: September, 2003
Inspection - Topics
IPC 610 Electronic Acceptability Standard
Manual Visual Inspection (MVI)
Solder Paste Inspection (SPI)
Automated Optical Inspection (AOI)
Automated X-ray Inspection (AXI)
Slide 20ITC Board Test Tutorial Part 1, Last revised: September, 2003
SPI (Solder Paste Inspection)
Introduction2D3DLaser TriangulationPotential defects and possible causesPros and Cons
Slide 21ITC Board Test Tutorial Part 1, Last revised: September, 2003
Paste P&P Reflow Paste P&P Reflow Hand-load
Wave
Side 1 Side 2
Defectsintroduced
Defectsintroduced
Defectsintroduced
&Defectsremoved Defects
introducedDefects
introduced
Defectsintroduced
&Defectsremoved
ManyDefects
introduced
For higher defect coverage.
For processcontrol with shorterfeedback loop.
Also defects introduced to side 1 Also defects introduced to SMT side 1&2
or Selective Wave
Where should test inspection be deployed?
Slide 22ITC Board Test Tutorial Part 1, Last revised: September, 2003
Main reasons for Solder Paste Inspection
• Many solder joint defects are caused by paste printingFor 0201s and CCGAs, paste volume and registration very important
• Defects are prevented at the most cost-effective stage
• Components are becoming more and more difficult and expensive to rework
• Repair costs are minimal since the board is unpopulated
• Can be used real time as a process control and process indicatortool
Slide 23ITC Board Test Tutorial Part 1, Last revised: September, 2003
• Vision alignment is used for precise stencil to board
registration, X-Y and Theta
also….
• 2D Paste Inspection Systems available on most machines.
Adds to cycle time and is limited.
•This part will focus on dedicated Paste Inspection Machines
Printers have vision too
Printing Equipment
Slide 24ITC Board Test Tutorial Part 1, Last revised: September, 2003
• High Speed Paste Inspection
- Enable the system to scan all deposits for volume, at line speeds
• Repeatability
- GR&R of less than 10%
• Board Warpage Compensation - Ability to handle large warp in double sided SMT boards
Important features of SPI
Slide 25ITC Board Test Tutorial Part 1, Last revised: September, 2003
Technology SPI 2D
• Camera
• Light
Slide 26ITC Board Test Tutorial Part 1, Last revised: September, 2003
Laser Line Generatorsor light
Light Ring Illumination for Fiducial Inspection
Camera LensCamera
Lighting Head & Camera 3D
Z-Axis
2nd Laser or light
Slide 27ITC Board Test Tutorial Part 1, Last revised: September, 2003
Laser Line Generatorsor light
Light Ring Illumination for Fiducial Inspection
Camera LensCamera
Lighting Head & Camera 3D
Z-Axis
2nd Laser or light
Laser or light
Camera
Camera
Slide 28ITC Board Test Tutorial Part 1, Last revised: September, 2003
Laser
Sheet of light
Paste deposit
PCB
2nd Laser
2nd Sheet oflight notshown
Beams fromtwo lasers
Laser Beam Head
Camera
Slide 29ITC Board Test Tutorial Part 1, Last revised: September, 2003
Laser beamD
Solder paste
Hα PCB
H = D * tan(a)
Laser Triangulation
Deflection of laser beam (D), is directly proportional to the height of the solder paste
Slide 30ITC Board Test Tutorial Part 1, Last revised: September, 2003
View with Laser 'A'
Laser A Laser B
No data 'shadow'
View with Laser 'B'
3D Height Data
Scan Direction
Scanning with 2 Lasers
Slide 31ITC Board Test Tutorial Part 1, Last revised: September, 2003
Combined Laser View
Laser A Laser B
Removed all'shadowing'
3D Height Data for allpoints
Combining Images from 2 LasersScan Direction
Slide 32ITC Board Test Tutorial Part 1, Last revised: September, 2003
1. Height Measurement on rigid PCB
2. Warped PCB throws off results
3. Z-axis compensation restores accurate results.
Z-Axis Compensation
Typically the laser and camera move
Slide 33ITC Board Test Tutorial Part 1, Last revised: September, 2003
Paste to Pad Offset / Misaligned Print
2DOffset defectPotential area defect
3DPotential volume defectPotential height defect
Adjust screen printerMeasure stencil and
boards
Mis-aligned stencilBad stencil or boards
Paste to Pad Offset
ActionPossible CauseSPI Measurement
Slide 34ITC Board Test Tutorial Part 1, Last revised: September, 2003
Bridge
2D Offset goodPotential area defect if bridge area is large
3DVolume defectPotential height defect
Collect 3D dataInspect stencil
Excess pasteDamaged apertures
Bridge
ActionPossible CauseSPI Measurement
Slide 35ITC Board Test Tutorial Part 1, Last revised: September, 2003
Smear
2D Offset goodPotential area defect if smear area is large
3DPotential volume defectHeight defect
Clean stencilPoor handlingPaste on back on stencil Snap-off height too high
Smear
ActionPossible CauseSPI Measurement
Slide 36ITC Board Test Tutorial Part 1, Last revised: September, 2003
Small Area / Large Area
2D Offset goodArea defect
3DVolume defectPotential height defect
Adjust printerClean stencil and board
Inspect stencil
Poor aperture gasketing due to excessive squeegee pressure
Debris on boarDamaged aperture
Large Area
Clean stencilAdd fresh paste
Adjust printer
Dried paste on stencil aperaturePaste volume on printer too low
Squeegee speed too fast
Small Area
ActionPossible CauseSPI Measurement
Slide 37ITC Board Test Tutorial Part 1, Last revised: September, 2003
Volume High or Low / Height High or Low
2D Offset goodArea good
3DVolume defectHeight defect
Adjust printerPolymer blades scoop out pasteSqueegee speed too fast
Volume LowHeight Low
Clean stencil and boardInspect stencil
Contamination at board/stencil interfaceWarped stencil
Volume HighHeight High
ActionPossible CauseSPI Measurement
Slide 38ITC Board Test Tutorial Part 1, Last revised: September, 2003
Slump / Large Height Variation
2D Offset goodPotential area defect
3DVolume defectHeight defect
Inspect stencilAdjust printer
Warped stencil Separation control speed too fast
Squeegee speed too fast
Large Height Variation
Adjust printerSqueegee speed too fastPaste temperature to high
Paste has absorbed moisture
Slump
ActionPossible CauseSPI Measurement
Dog Ear
Slide 39ITC Board Test Tutorial Part 1, Last revised: September, 2003
Defect Identification
Paste to pad offset/ Misaligned print
Small area/ Large area
BridgeSlump/ Large height variation
Volume high or low/ Height high or low
Smear
Both 2D and 3D provide valuable process informationSome overlap exists between 2D defect calls and 3D defect callsOnly 3D inspection provides volume measurements.
We know from case studies and publications that the solder paste volume information is a good predictor of finished board quality.
Slide 40ITC Board Test Tutorial Part 1, Last revised: September, 2003
Advantages
Both 2D and 3D SPI provide valueProcess control
Finding defects (potential defects)
3D inspection provides the added value of volume information, which is important producing robust jointsCatching defects early, pre-placement saves money, easy repair
Slide 41ITC Board Test Tutorial Part 1, Last revised: September, 2003
Disadvantages
Defect introduced after paste will not be caughtA balance between repairing “potential defects” and letting them passLimited value if not enough attention to process information is used.
Slide 42ITC Board Test Tutorial Part 1, Last revised: September, 2003
Inspection - Topics
IPC 610 Electronic Acceptability Standard
Manual Visual Inspection (MVI)
Solder Paste Inspection (SPI)
Automated Optical Inspection (AOI)
Automated X-ray Inspection (AXI)
Slide 43ITC Board Test Tutorial Part 1, Last revised: September, 2003
AOI (Automated Optical Inspection)
LaserTechnologyPros and cons
CameraCameraLighting sourceColor - MonochromeAlgorithmWarp compensation
Pre-reflow - Post-reflowPros and Cons
Slide 44ITC Board Test Tutorial Part 1, Last revised: September, 2003
Component Position Test
SensorsLaser Source
Laser
Slide 45ITC Board Test Tutorial Part 1, Last revised: September, 2003
Sensors
Laser Source
Solder Joint Test
Laser
Slide 46ITC Board Test Tutorial Part 1, Last revised: September, 2003
Disadvantages:• Limited Polarity• Limited Curvature• Speed
Advantages:• High Accuracy
Laser
Slide 47ITC Board Test Tutorial Part 1, Last revised: September, 2003
Top Camera Only
CCD Camera, typical area CCDnot line scanner
Visible LightSource
Top Camera Only
Limited J-lead
Slide 48ITC Board Test Tutorial Part 1, Last revised: September, 2003
Top Camera Only
CCD Camera, typical area CCDnot line scanner
Visible LightSource
Possibility for several Camera
Top Camera Only
Limited J-lead
Slide 49ITC Board Test Tutorial Part 1, Last revised: September, 2003
CCD Cameras
Visible LightSource
Angled Cameras
Focus point, warpage problem
Angled Cameras
Slide 50ITC Board Test Tutorial Part 1, Last revised: September, 2003
“Penta” Optical Head
CCD Cameras
Visible LightSource
Focus point, warpage problem
Slide 51ITC Board Test Tutorial Part 1, Last revised: September, 2003
Advantages:• “Everything Visible”
Disadvantages:• No Hidden Joints• Limited J-lead
Single Camera Multiple Camera
Advantages:• “Everything Visible”
Disadvantages:• No Hidden Joints• Calibration
Camera
Slide 52ITC Board Test Tutorial Part 1, Last revised: September, 2003
Typical Illumination Systems
C C
C
C
C
C
C
C
C
C
Fluorescent Ring Lighting LED lighting Flash tube
lightingLED
Ring Lighting
Slide 53ITC Board Test Tutorial Part 1, Last revised: September, 2003
Visible Light Source:• Halogen light• LED• High frequency fluorescent• Flashes
Disadvantages:• Lifetime & calibration• Intensity• Lifetime & calibration• Lifetime
Lighting Sources
Slide 54ITC Board Test Tutorial Part 1, Last revised: September, 2003
Technologies: Disadvantages:• Diffuse light No curvature information• Directed light Different specula reflections• 3D Lighting Possible speed impact
Lighting Technologies
•
•
•
Slide 55ITC Board Test Tutorial Part 1, Last revised: September, 2003
Color and Monochrome Systems
Why is color used?Used to get solder fault coverage in 2D systemsProvide choices for optimizing contrast between item of interest and backgroundAngled, colored lighting substitutes for angled camerasRead laser marks
Pros and Cons of colorMay induce unwanted “noise” into images• Color is sometimes a non-controlled process variable on PC assemblies.
• Manufacturers usually don’t spec or care about color of packages or boardsAdded processing may impact throughputSome solutions have trouble with lead-free solder inspection
Can either be color camera or color lighting
Slide 56ITC Board Test Tutorial Part 1, Last revised: September, 2003
ChipLength
ChipWidth
CorrelationProgramming: no programming, uses images from camera as search template.Advantages: zero programmingDisadvantages: sensitive to background, high false calls, multiple boards to program
Feature ExtractionProgramming: Manually input device dimensions or edit from similar deviceAdvantages: robust algorithms with low false fails. Good on jointsDisadvantages: more complex programs, sensitive to component changes
Geometric Pattern Matching (GPM)Programming: Draw (or link to) models based on device shapeAdvantages: Simple intuitive programming, scales and rotates with deviceDisadvantages: can not model joints, grayscale only
3 Major Algorithm Types
Slide 57ITC Board Test Tutorial Part 1, Last revised: September, 2003
Warp Correction
To achieve low false flag and escape rates, warp correction is a mustBoard warp causes the image to move within inspection windowsWarp correction system digitally or mechanically compensates for it during
inspection
Angled Cameras and Lighting Systems Require Warp Correction
Slide 58ITC Board Test Tutorial Part 1, Last revised: September, 2003
AOI Pre-reflow - Post-reflow
Post-reflow + Catching more defects- Not as efficient for process control
SPI
AOI pre-reflow
AOI post-reflow
Pre-reflow - Catching fewer defects+ Efficient for process control
Slide 59ITC Board Test Tutorial Part 1, Last revised: September, 2003
AOI
Disadvantages:“Hidden joints” (BGA, RF-shields) Can have high false callsNot the highest defect coverage
Advantages:High throughputGood defect coverageRelative low costNo fixtures
Slide 60ITC Board Test Tutorial Part 1, Last revised: September, 2003
Inspection - Topics
IPC 610 Electronic Acceptability Standard
Manual Visual Inspection (MVI)
Solder Paste Inspection (SPI)
Automated Optical Inspection (AOI)
Automated X-ray Inspection (AXI)
Slide 61ITC Board Test Tutorial Part 1, Last revised: September, 2003
AXI (Automated X-ray Inspection)
IntroductionAutomated and Manual
High end Manual X-rayPros and Cons
2D AXI -TransmissionTechnologyPros and Cons
3D AXI - Cross sectionalLaminography - TechnologyTomosynthesis - TechnologyPros and cons
Combo - Pros and Cons
Lead-free and x-ray
Slide 62ITC Board Test Tutorial Part 1, Last revised: September, 2003
General X-Ray Overview
X-ray beam
X-ray sensitive material
Attenuation
Light created x-ray attenuation
BGAs Under Direct Transmission 2D X-ray
Slide 63ITC Board Test Tutorial Part 1, Last revised: September, 2003
Types of AXI
Transmission AXI “2D”Cross-section AXI “3D”
LaminographyDigital Tomosynthesis
Combo AXI (2D and 3D)
Transmission MXI “2D”
ManualAutomatic
Slide 64ITC Board Test Tutorial Part 1, Last revised: September, 2003
Manual 2D X-Ray Systems
Continued product segmentation between very low cost/limited capability systems and higher cost/higher capability systems.
For higher end products there is increased use of multiple axis manipulation for better inspection capability and in some cases the ability to “capture” images at different angles to provide a “pseudo” 3D image.
Increased use of software to automated” defect calls - especially for BGA/area array packages
These systems do NOT use laminography or Tomosynthesis and are not suitable where in-line or automated handling are required.
High End Manual 2D X-Ray Systems Continue to Increase Capability
Slide 65ITC Board Test Tutorial Part 1, Last revised: September, 2003
Manual 2D Transmission x-ray
Disadvantages:Marginal accuracyFalse call potential increasesOperator oriented (fulltime)Slower than automated systemsOperator must manually move DUT to area of interestCan’t be used for highly populated double sided boards
Advantages:No ProgrammingSystem will not shut down line if failure occursLower support costs than automated systemsEasy to use
Slide 66ITC Board Test Tutorial Part 1, Last revised: September, 2003
Defect coverage AXI
AOI
• Poor wetting• Marginal Joints• Voids• Excess
• Shorts• Opens• Hidden
parts
• Missing• Gross Shorts• Lifted Leads• Bent Leads
•Bridging• Insufficient•Tombstone•Misalignment•Bypass Caps
•Orientation• Missing non-
electrical parts•Mark Inspection•Paste Deposition
Defects
•Polarity•Inverted
• Dead part• Wrong part• Bad part• PCB short/open • Functionally bad
ICT AXI
This is a conceptual
diagram!
Slide 67ITC Board Test Tutorial Part 1, Last revised: September, 2003
2D - Transmission AXI
Bridge
The entire solder volume is inspected by transmission AXI
Slide 68ITC Board Test Tutorial Part 1, Last revised: September, 2003
2D - Transmission AXI
2D AXI finds “out-of-slice” defects
Finds defects that 3D AXI cannot typically detect
Slide 69ITC Board Test Tutorial Part 1, Last revised: September, 2003
Physical Layout of Double-sided Board
2D X-ray Imageof Double-sided Board
What About AXI Test Access?
J-lead
Resistor
PCB
Non or Partially Testable Joints
Slide 70ITC Board Test Tutorial Part 1, Last revised: September, 2003
COMPLEXITY BOARD SIZE [IN]
TOTAL # COMP.
TOTAL # JOINTS
% ACCESS
Low 12x2.7 454 2036 79% Medium 14x7 1,071 7112 55% High 13 x 16.5 1,710 11,115 72% High 14.5 x 16 2375 13,904 73% High 13.5 x 17 2918 24,758 79%
2D AXI Provides Good Test Access on Double Sided Boards
2D - Transmission AXI
Your “mileage” may vary
Slide 71ITC Board Test Tutorial Part 1, Last revised: September, 2003
2D - Transmission AXI
Disadvantages:Must have qualified programmerLimited applicability on double sided boardsLearning curve to program systemSeveral Algorithms to learn and understand
Advantages:High ThroughputAccurateReliable calls (if programmed properly)No operator Intervention required for inspection
Slide 72ITC Board Test Tutorial Part 1, Last revised: September, 2003
2D vs 3D X-Ray Inspection
Under 2DInspection
Bottom
Top
Under 3DInspection
Slide 73ITC Board Test Tutorial Part 1, Last revised: September, 2003
3D Cross-Section AXI
Laminography• Mechanical Image Integration
• Z-Axis Mappingrequired
RotatingDetector
Rotating X-ray Beam
Focal plane
Slide 74ITC Board Test Tutorial Part 1, Last revised: September, 2003
3D Cross-Section AXI Laminography
PCB
~ 60 mils
Majority of solder joints 3-4 mils
BGA, CCGA solder joints 15-70 mils
Through hole pin
Only solder joints and PCB thickness to scale
Slice 1Slice 2
Slice 4
Slice 3
Focal depth of each slice 3-4 mils
Slide 75ITC Board Test Tutorial Part 1, Last revised: September, 2003
X-Ray Measurements
Sensor
CalibrationData
ImageProcessor
20.0
00.0
X-ray image with 5 gullwing pins
Gullwing pin IC
Solder
Slide 76ITC Board Test Tutorial Part 1, Last revised: September, 2003
3D Cross Section AXI Technology
Image Acquisition
Digital Tomosynthesis
Cross-section Formation
Cross-section Height Definition
Laminography
Digitally computed
Electro-mechanically initialized via
laser surface map
Independent off-axis
transmission images
Software focal plane
shift
Synchronous mechanical rotation and
movement of x-ray beam,
detector and Z table
Slide 77ITC Board Test Tutorial Part 1, Last revised: September, 2003
3D Cross-Section AXI
Tomosynthesis• Digital Image Synthesis
StationaryDetector
• No Z-Axis Mappingrequired
• Computational intensive
Slide 78ITC Board Test Tutorial Part 1, Last revised: September, 2003
Principle of Digital Tomosynthesis
Individual transmission images are acquiredLater digitally synthesized to produce x-section views or “slices”Image acquisition and image synthesis are independent stages
A
HGF
D CE
B
C
EB
AH G F
D
Large AreaDetector
SteerableX-Ray Source
Inspection Plane
Slide 79ITC Board Test Tutorial Part 1, Last revised: September, 2003
Physical Layout of Double-sided Board
Transmission (2D) X-ray Imageof Double-sided Board
AXI Test Access
QFP
Resistor
PCB
Non or Partially Testable Joints
Slide 80ITC Board Test Tutorial Part 1, Last revised: September, 2003
Digital Tomosynthesis - Slices
Multiple off-axis Transmission X-ray images are used to separate the top and bottom board side. Thereby, separating overlapping or obscured solder connections
Top Side
Bottom Side
3D X-ray provides the capability to generate
separate views of top and bottom side joints
A Method for separating and analyzing data on opposite sides of a PCBA
Off-Axis Transmission Images
JLead
ResistorPCB
Slide 81ITC Board Test Tutorial Part 1, Last revised: September, 2003
Digital Tomosynthesis
Digital Tomosynthesis is aComputational Technique
Objects at different elevations move by different horizontal distances
Z= X / tan Z
X
Slide 82ITC Board Test Tutorial Part 1, Last revised: September, 2003
InspectionPlane
EA
Image E Image A
Large Area Detector
Digital Tomosynthesis
Slide 83ITC Board Test Tutorial Part 1, Last revised: September, 2003
Tomosynthesis
TomosynthesisMultiple Cross-sections per Acquisition: ‘infinite slicing’
1
Slide 84ITC Board Test Tutorial Part 1, Last revised: September, 2003
Digital Tomosynthesis and Combo
De-coupling capacitors are increasingly placed directly below otherinterconnections to deliver controlled impedance and higher frequencies Tomosynthesis can completely remove ‘shading effects’ from the
opposite of the board
1 of 8 off-axis views of BGA Tomosynthesis view of BGA
Slide 85ITC Board Test Tutorial Part 1, Last revised: September, 2003
3D Cross-Section AXI
Disadvantages:Must have qualified programmerLonger learning curve to program systemSeveral Algorithms to learn and understand
Advantages:AccurateReliable calls (if programmed properly)No operator Intervention required for inspectionMultiple Slices on any solder joint
Slide 86ITC Board Test Tutorial Part 1, Last revised: September, 2003
Combo AXI
A combination of 2D transmission and 3D cross-section automatic x-ray
Slide 87ITC Board Test Tutorial Part 1, Last revised: September, 2003
Combo AXI
Disadvantages:Longer Programming TimesSlower Inspection Speed in 3D mode
Advantages:Apply transmission and cross-section where they are best suitedCan remove shading effects to delivery high quality x-ray images
Slide 88ITC Board Test Tutorial Part 1, Last revised: September, 2003
Lead-Free Solder -- X-ray Images
Tin/Lead Joint
Tin/Silver/Copper Joint Tin/Silver/Copper paste
Tin/Lead coated Lead
Implication:
Slide 89ITC Board Test Tutorial Part 1, Last revised: September, 2003
Paste P&P Reflow Paste P&P Reflow Hand-load
Wave
Side 1 Side 2
Defectsintroduced
Defectsintroduced
Defectsintroduced
&Defectsremoved Defects
introducedDefects
introduced
Defectsintroduced
&Defectsremoved
ManyDefects
introduced
For higher defect coverage.
For processcontrol with shorterfeedback loop.
Also defects introduced to side 1 Also defects introduced to SMT side 1&2
or Selective Wave
Where should test inspection be deployed?
Slide 90ITC Board Test Tutorial Part 1, Last revised: September, 2003
Inspection - Topics
IPC 610 Electronic Acceptability Standard
Manual Visual Inspection (MVI)
Solder Paste Inspection (SPI)
Automated Optical Inspection (AOI)
Automated X-ray Inspection (AXI)
