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GE
Sensing & Inspection Technologies
A GUIDE TO
THE INSPECTION
AND ANALYSIS
OF ELECTRONIC PACKAGES
with phoenix|x-ray microfocus and nanofocus X-ray systems
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FAQs about X-ray
source
small FOD large FOD
object
FDD
detector
high magnification
insulator
cathode
(filament)
grid
anode
deflection
unit
magnetic
lens
target
electron beam
X-ray beam
low magnification
U
UGU
H
ACC
Why can the collision
protection be deactivated?
phoenix|x-ray systems come standard with
a password-protected, anti-collision feature
to ensure the protection of your samples.
When inspecting certain samples, it might
become necessary to deactivate the collision
protection (e.g. with 25 m bond wires, which,
even for magnifi cations of just 500 x, need
to be as close as 4 mm to the tube head).
phoenix|x-ray provides the user the fl exibility
when dealing with small samples. Unlike
with conventional systems, the X-ray tube is
located above the sample tray allowing the
user to move the sample as close to the tube
head as needed.
FOD = -4 mm: 500 x Sample touching the tube:
How X-ray inspection
works
X-ray starts with a sample being irradiated by an X-ray source and projected onto a
detector. The geometric magnification M of the image is the ratio of focus-detector
distance (FDD), Focus-object distance (FOD): M=FDD/FOD. The smaller the focal spot,
the greater the resolution. With the nanofocus technology a unique detail detectability down to 0.2 microns can be achieved. phoenix|x-ray systems reach geometric
magnifications over 2 000 x resulting in total magnifications beyond 24 000 x.
How X-ray tubes
work
The heart of the X-ray machine is an electrode pair consisting of a cathode, the fi la-
ment, and an anode, that is located inside a
vacuum tube. Current is passed through the
fi lament heating it up, causing the fi lament
to emit electrons. The positively charged
anode draws the electrons across the tube.
Unlike with conventional X-ray tubes, the
electrons pass through the anode into a specifi cally designed set-up of electromagnetic
lenses, where they are bundled and directed
onto a small spot on the target, a fl at metal
disc covered by a layer of tungsten. When
the electrons collide with the target, they interact with the ions in the tungsten, causing
X-rays to be emitted. Key to sharp, crisp
X-ray images at micron or even submicron
resolutions is the size of the focal spot,
meaning the ability to focus the electron
beam in such way that the area on the target
where the electrons hit be as small as possible – an obstacle yet to be overcome by
conventional X-ray machines.
However, phoenix|x-ray has mastered this
challenge with its unique nanofocus tube
providing detail detectabilities as low as 200
nanometers (0.2 microns).
Maximum magnification
What makes an excellent
X-ray?
In addition to resolution, maximum voltage,
and power, stability is very important for
reliable results and highest up-time. One of
phoenix|x-ray’s key techno-logy competencies are tube design and manufacturing.
0.50
0.25
0.00
dose rate variation [%]
-0.25
-0.50
1234
0
• High power nanofocus X-ray tubes up
to 180 kV and unipolar microfocus X-ray
tubes up to 300 kV maximum voltage
• Up to 200 nm (0.2 microns) detail detecta-
bility
• Dose-rate stabilization: the emitted
intensity only varies by less than 0.5 %
within 8 hours (see diagram)
• Anti-arcing: dedicated surface treatment
during fabrication and automated warmup procedures prevent discharges
• Self adjustment: all tube adjustments are
performed automatically during warm-up
to achieve optimum results
• Plug-in cathodes: pre-adjusted spare cath-
odes prevent malfunction due to wrong
filament adjustment and minimize downtime to less than 20 min.
• Target check: target condition is checked
automatically; automatic target wear is
indicated
dose rate stability XS|160 T
0.5%
5678
time [h]
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The View Inside
What can X-ray inspection tell us about package quality?
Electronic packages are sophisticated electronic devices with complex, internal features. In order to meet the quality requirements of the industry, X-ray inspection solutions must be capable of delivering detail detectabilities in the submicron range and
detecting hidden defect fl aws.
phoenix|x-ray o ers automated microfocus and nanofocus X-ray inspection solutions for any package inspection task including,
but not limited to the following:
Standard IC packages: DIP, SOT, VSOP, (P)LCC,
QFP, Flat Pack
Cracked wire
Wire destroyed by overvoltage
IC-package, top-down view
Any internal details such as bond wires, inner and outer bonds, die,
die attach, lead frame and moulding can be examined for defects (e.g.
broken wires, excessive wire sweep, extraneous or crossing wires, die
attach voids and die tilt, die cracks, defective lid seals, moulding voids,
entrapped particles and delaminations).
Wire-bonded area array packages:
PBGA, CSP, etc.
Chip-scale package in top-down view (not balled yet)
The image gives a clear view of the integrity of the vias and lead tracks of
the PCB and the quality of the solder joints.
>
Wedge-bond inspection
>
>
>
Shape deviations and opens
in flip-chip bonds
>
Ball-bond inspection
>
Bridge between flip-chip
bonds
Flip-chip bonded area array packages:
CBGA etc.
FC-bonded IC, top-down view
Applications include the inspection of microscopic solder joints connecting IC and ceramic substrate as well as underfi ll inspection. The most
common defects are open solder joints, missing solder joints, solder
bridges, solder and underfi ll voids.
>
Die attach
voids
Cracked die
>
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