Introduction to x-rays and x-ray inspection, Safety Operating X-Ray Cabinet Systems, Size and Weight of X-Ray Inspection Systems, How do we image the X-rays?, Magnification, Resolution, Field of View, X-Ray Inspection Area, Power of X-Ray Tube, X-Ray Sensor, Sample Positioning, x-ray applications, LED Packaging and Assembly, Semiconductor Failure Analysis, Component Counterfeit Detection, Electronic Component Manufacturing, PCB / PTH (barrel fill) Analysis, Smart Phone Design and Manufacturing, BGA Void and Head – in Pillow Analysis, RF Components and Systems, Automotive Parts, Non Destructive Testing and Evaluation, Parts – Presents- Placement, Plastic / Aluminum Molding, Medical Device Design and Manufacturing, Small Animal Imaging, Seed and Agricultural Imaging, Identification of defects in soldered components – excess voiding or excess solder, Quality control of medical temperature sensors. X-Ray images taken with TruView X-Ray Inspection systems.

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LED, BGA, and QFN
Assembly and Inspection Tutorial

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Medical
Contract-
Electronics
Semi
Research
Consumer
Automotive
Industrial
Avionics
Introduction to X-Ray Inspection

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10 Basic Principles of X-Ray Inspection
Safety Operating X-Ray Cabinet Systems
Size andWeight of X-Ray Inspection Systems
How do we image the X-rays?
Magnification
Resolution
Field ofView
X-Ray Inspection Area
Power of X-Ray Tube
X-Ray Sensor
Sample Positioning

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Safety Operating X-Ray Cabinet Systems
The Food and Drug
Administration regulates all
cabinet x-ray systems:
Redundant interlocks
Warning lights
Maximum radiation allowed.
FDA 21 CFR
1020.40(c)(1)(i) specifies
“radiation emitted from the
cabinet x-ray system shall
not exceed an exposure of
0.5 mR/h at 5cm from the
external surface”
Operators can safely work
on the x-ray inspection
system in a full time capacity
with no danger to their
health.

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Size and Weight of X-Ray Inspection Systems
• The size of the x-ray cabinet is a direct function to the
maximum sample size that can be inspected and the
amount of manipulation that can be achieved.
• The weight of the x-ray cabinet is also a function of
the size of the cabinet. Larger cabinets often weight
more than smaller cabinets.
• Another important parameter that determines the
weight of a cabinet is the maximum power of the x-
ray source. More powerful x-ray sources need more
shielding material – lead and steel – to keep radiation
inside the cabinet. As a result, systems with very
powerful x-ray sources tend to be very heavy.

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Introduction to X-rays
Why use microfocus X-ray sources?
Microfocus means that the size of the X-ray source is only a few microns across
(1 micron or 1µm is 1/1000th of one millimeter).
Using a small X-ray source means that we can magnify the X-ray images on to
the detector and thus see more detail.
Microfocus source
(~33µm to 5µm)
Typical medical
X-ray source
(~1mm)
Large sharp imageLarge blurred image
Object

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How do we image the X-rays?
When X-rays hit certain materials, they cause them to fluoresce. In this process, the
energy of the X-ray is absorbed and re-emitted as visible light. Usually this light is very
faint and needs to be amplified, else very sensitive detectors need to be used.
Flat Panel Detector standard in
all TruView X-Ray inspection
systems. Photo byTeledyne
Technologies.
Image intensifier available for
TruView X-Ray inspection
systems. Photo by Hamamatsu
Corporation

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How do we get a magnified image?
10
Just like light,X-rays travel in
straight lines.
Unlike light,we cannot use a
lens, so we use geometric
magnification.
The magnification is increased
by moving the sample closer to
the X-ray source (and vice
versa).

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Resolution
The X-ray source size can be measured with a resolution test pattern, as shown here
Electron microscopy image of test pattern
5µm
1µm
Outer bar width = 5 mm
Inner bar width = 1 mm
Thickness 1 mm gold

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Field of View
The electron beam generated by the
cathode is rapidly accelerated against
the anode. Upon colliding with the
anode, a cone-shaped beam of x-rays is
generated
As the x-ray beam moves farther from
the anode target, the diameter of the
beam increases proportionally.The angle
of the x-ray cone beam, α, is determined
by the angle of the anode target
Diameter of the x-ray beam increases as
it moves away from the source
Magnification is a function of the
distances between source, sample, and
detector

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X-Ray Inspection Area
Inspection area is the
total size of the x-ray
chamber. In other words,
the size of the largest
object that can be placed
inside the x-ray machine.
Viewable area, on the
other hand, accounts for
the maximum area of the
object that can be seen
in the x-ray machine.
TruView Prime
TruView Elite

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Power of the x-ray tube
The power of the x-ray tube is composed of
two parameters: voltage (rated in kilovolts, or
kV) and current (rated in milliamperes, or mA).
The voltage determines the maximum energy of
the x-ray photon produced by the source.
Higher energies have more penetrating power,
so x-ray sources with higher kV can penetrate
denser materials.
The proper determination of how many kV you
need for your application is critical: price goes
up fast with kVs!
The current of the source is a measure of how
many x-ray photons are being produced in a
certain amount of time.As a result, increasing
the current of the x-ray source produces a
brighter image – at the same penetration level.

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Sample positioning
Modern x-ray inspection
systems have migrated to
semi or fully automated
manipulation of samples
inside the cabinet.
With these systems the
user can safely manipulate
the sample inside the
machine without a direct
contact with the sample.
Multiple degrees of freedom
are available to allow the
user to image the sample.

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Applications include…
• Semiconductor and passive electronics component
Inspection
• Surface mount and through hole PCB solder joint
Inspection
• Ball Grid Array (BGA) inspection
• IC Wire bond and Die Attach inspection

15. LED(Packaging(and(Assembly Semiconductor(Failure(Analysis

16. Electronic(Component(
Manufacturing
Component(Counterfeit(Detection

17. PCB(/(PTH(Analysis Smart(Phone(Design(and(Manufacturing

18. BGA(Void(and(Head(– in(Pillow(Analysis

19. RF(Components(and(Systems Automotive(Parts

20. Parts(– PresentsL PlacementNon(Destructive(Testing(and(Evaluation

21. Plastic(/(Aluminum(Molding( Medical(Device(Design(and(Manufacturing(

22. Small(Animal(Imaging Seed(and(Agricultural(Imaging(

23. Identification of defects in soldered
components – excess voiding or excess solder

24. PCB – Sample Image 1
At a medium magnification it is useful to look for PCB level
quality. This PCB shows good via to pad registration. It is a
useful image to look for die attach level quality issues.

25. PCB – Sample Image 2
Higher magnification to expose the large BGApart under the heavy heat sink.
Even with the heavy heat sink, the high definition flat panel camera show details of each ball to
assess potential shorts and opens under the BGA.

26. PCB – Sample Image 3
This image shows some excess voiding on the
pads of this surface mount component. This is a
possible indication of manufacturing issues.

27. PCB(– Sample(Image(4
Higher magnification shows inner details of several
components, allowing us to verify any processing
potential problems like wrong temperature cycles
and defective stencils.

28. A high magnification image of surface mount devices allow us to
inspect the quality of solders and other voiding.
It would be possible to see lifted pins, shorts, opens, and
misplaced parts. The detail of the imaging system allows us to see
the details inside the parts, including the wire bonds inside this
SMT component.
PCB – Sample Image 5

29. Inspection of wirebonds
TruView’s resolution
allows for inspection
of metal layers on the
ASIC

30. Inspection of PCBs with EMI shields, when
optical is no longer an option – TV, cell phones,
RF boxes
FAIL: Short on
SMD part
Detail

31. Quality Control

32. Defect inspection of BGA and QFN
Damaged balls
during assembly

33. Close up of wire bonds

34. Quality control of medical temperature sensors
FAIL: Electrodes are too close, which may
lead to a catastrophic fail during use in a
critical medical monitoring application

35. Inspection of microwire connections inside
components