Basic Principles of X-Ray Inspection for BGA’s. Increased Use of BGA’s Ball Grid Arrays - array...
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Transcript of Basic Principles of X-Ray Inspection for BGA’s. Increased Use of BGA’s Ball Grid Arrays - array...
![Page 1: Basic Principles of X-Ray Inspection for BGA’s. Increased Use of BGA’s Ball Grid Arrays - array of solder ball connections underneath component Provides.](https://reader036.fdocuments.us/reader036/viewer/2022070307/551b5f6c5503465c7e8b61c6/html5/thumbnails/1.jpg)
Basic Principles of X-Ray Inspection for BGA’s
![Page 2: Basic Principles of X-Ray Inspection for BGA’s. Increased Use of BGA’s Ball Grid Arrays - array of solder ball connections underneath component Provides.](https://reader036.fdocuments.us/reader036/viewer/2022070307/551b5f6c5503465c7e8b61c6/html5/thumbnails/2.jpg)
Increased Use of BGA’s
Ball Grid Arrays - array of solder ball connections underneath component
Provides many advantages over leaded components– Reduced component size– Increased I/O count– Smaller footprint– Increased performance
characteristics
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The Problem with BGA’s
How to verify a solder bond that cannot be observed?
Hidden joints - touch up not possible
Only way to test integrity of joints – Electrical test– Look Under/Video Scope– X-Ray
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How X-Rays Work
image
Presence or Absence of Material
wedge objectx-rays x-raysdetector
imagedetectorlow density
high density material
x-raysx-rays
Differences in Material Density
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X-ray tube generatesx-ray energy
X-rays absorbed where density exists in sample - remaining x-rays pass through & strike the detector
Detector converts x-rays to visible light, video camera sends image to processor
Image Processor enhances x-ray images for high-resolution viewing
The image you see
How an X-Ray System Works
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Solder Connections Under X-Ray Analysis Main characteristic:
uniformity of the connections
If X-ray shows all connections uniformly circular & equal in area - good indication of complete/proper reflow
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Nearly all Defects have “Signatures”
Bridging, missing balls, large voids obvious
Other defects subtle Look for pattern in distortion of
size/shape of bond image Operator learns to identify
defect signatures, process problems and quickly make adjustments
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May be due to excess paste or flux
Improper rework implicated
Solder splattering due to poor reflow conditions
Defects Identified by X-Ray: Bridging
Look Under Scope Image
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Misregistration
Result of errors in component placement Possible issues with solder mask alignment
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Insufficient Reflow
More difficult to spot If package misplaced,
ball shape may be elliptical (easier to identify)
Bond distribution not consistent
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Can occur in manufacturing process
Usually due to mishandling
Missing Balls
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Cold Solder
More difficult to identify Signified by jagged
irregular edge around the perimeter of the solder ball
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Solder Voids
Result of moisture in BGA package – must be thoroughly baked out
Problems with solder paste
Huge issue with lead-free solder
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Voids a process indicator, not defect unless excessively large
Motorola Study - balls that contain voids up to 24% more reliable than those without voids!
Solder Voids
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At 70 kV
Associated with camera used in many X-ray systems
As voltage increased, void artificially appears to expand (bloom)At 50 kV
Makes void appear larger than it really is
Glenbrook systems not subject to voltage blooming
Solder Voids & Voltage Blooming
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Potato Chipping/Popcorning
BGA’s outside edge lifts up from a pad
Center joints squashed due to compression under die area
Caused by moisture in BGA or excessive topside temperature
Normal
Potato Chipping
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Note distortion/ warpage of ball bonds lower right corner
View through Look-Under scope. Note package peeling away from solder ball
Potato Chipping/Popcorning
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Opens (require angled viewing)
Ball smaller than adjacent balls
Pad shadow seen below indicating no contact between ball & pad
Note two unattached spherical shapes unlike oval shapes adjacent to it– indicate no contact
between pad & solder ball
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RTX-113HV X-Ray Inspection System Features powerful 80 kV
X-ray tube GTI-5000 image processor
with auto-BGA analysis software
Sees through dense multilayer PCBs & metal capped BGAs
Variable Angle Viewing allows for 45 degree viewing
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GTI-5000 Image Processing Software
Provides analysis of BGA defects: bridging, voids, missing balls
Measures BGA ball size, ball roundness & void size
Software identifies any ball outside of set tolerance Includes CPU, Frame Grabber, Software, Color
Monitor
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Variable Angled Viewing
Allows for 45 degree viewing X-Ray source is rotated Allows inspection for full
range of hidden BGA defects:– Missing or mis-registered
solder spheres – Misalignments– Gross solder voids – Non-wetting or non-contact
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Operating voltage: 120V, 50/60 Hz Energy sensitivity: < than 15kV to >160 kV X-Ray Tube – 80 kVA Resolution: >20 line pairs per millimeter; can easily
resolve a 1 mil bond wire Magnification: 4 - 50x Maximum field of view: 1” diameter circle Maximum PCB size: 27” x 27” (685mm x 685mm)
with PCB manipulator
Specifications: RTX-113HV
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Other Real-Time X-Ray Inspection Systems from Glenbrook TechnologiesJewelBox Series
80 or 90kV 5-7, or 10 micron Focal
Spot size 7x-2000x magnification 5 Axis, 360o Positioner
RTX-113
35-52kV 20 line pairs/mm resolution
(up to 100 optional) Variable Angle Viewing
option available
RTX-Mini
40kV 20 line pairs/mm
resolution Truly Portable – can be
hand carried or shipped!
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11 Emery AveRandolph, NJ 07869
Tele: (973) 361-8866Fax: (973) 361-9286
[email protected] www.glenbrooktech.com
Manufacturer’s RepAaron Caplan
1310 E. Maple AveSterling, VA 20164
(703) [email protected]
www.gsaservice.com
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11 Emery AveRandolph, NJ 07869
Tele: (973) 361-8866Fax: (973) 361-9286
[email protected] www.glenbrooktech.com
Manufacturer’s RepAaron Caplan
1310 E. Maple AveSterling, VA 20164
(703) [email protected]
www.gsaservice.com