IPC-TM-650 EN 2022 试验方法-- - 第469页

Note: Material in this T est M ethods Manual was voluntarily establis hed by T echni cal Committees of IPC. Thi s mat erial is a dvisory only and its use or adaptation is entirely voluntary . IPC disclaims all lia bility…

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IPC-TM-650
Page 11 of 11
Number
2.5.5.5.1
Revision
Subject
Stripline
Test
for
Complex
Relative
Permittivity
of
Circuit
Board
Materials
to
14
GHz
Date
3/98
8.7
The
temperature
of
the
test
fixture,
if
not
in
the
21
to
23℃
range.
8.8
Any
conditioning
prior
to
measurement.
8.9
The
orientation
of
the
resonator
with
respect
to
X
or
Y
axis
of
the
specimen.
8.10
For
each
resonance,
show
8.10.1
through
8.10.9.
8.10.1
The
node
number
n.
8.10.2
The
calculated
effective
stripline
permittivity.
8.10.3
The
calculated
effective
dielectric
loss
tangent.
8.10.4
The
resonant
frequency,
fr,
at
maximum
transmis¬
sion.
8.10.5
The
insertion
loss
at
resonance,
dBr,
at
maximum
transmission.
8.10.6
The
Q|Oaded.
(optional).
8.10.7
The
calculated
Qunioaded
(optional).
8.10.8
If
the
three
point
method
of
6.3, 6.4,
or
6.5.1
is
used,
report
the
frequency
and
dB
value
of
the
two
points
either
side
of
the
peak
(optional).
8.10.9
If
the
non-linear
regression
(NLR)
method
of
6.5.2
is
used,
report
the
number
of
data
points
used,
NLR
uncertainty
values
(for
fr,
Q|Oaded,
dBr)
and
the
standard
deviation
of
the
fit
in
dB
units
(optional).
9
.0
Notes
9.1
Permittivity
The
dielectric
of
a
stripline
circuit
affects
the
electrical
response
of
all
the
circuits
printed
on
it.
Velocity
of
propagation,
wavelength,
and
characteristic
impedance
all
vary
with
permittivity.
If
the
permittivity
varies
from
the
design
value,
the
performance
of
such
circuits
is
degraded.
Throughout
this
document,
the
term
u
permittivity"
refers
to
relative
permittivity
of
the
dielectric
material,
a
dimensionless
ratio
of
the
absolute
permittivity
of
the
material
to
that
of
a
9.2
Loss
Tangent
The
attenuation
and
Q
(figure
of
merit)
of
stripline
circuits
are
a
function
of
combined
copper
and
dielec¬
tric
loss.
An
excessively
high
loss
tangent
leads
to
loss
in
sig¬
nal
strength
and
to
degraded
performance
of
frequency
selec¬
tive
circuits
such
as
filters.
9.3
Dielectrics
Clad
with
Thick
Metal
on
One
Side
This
method
can
be
used
for
measurements
of
dielectric
sub¬
strates
with
thin
foil
on
one
side
and
thick
cladding
such
as
aluminum
sheet
on
the
other
by
using
the
Type
C
specimen
configuration.
In
some
cases,
with
very
thick
metal
cladding
it
may
be
necessary
to
use
a
modified
part
5.1
.2
(Figure
4)
with
a
reduced
thickness
dimension.
9.4
Anisotropic
Materials
For
anisotropic
materials,
test
methods
in
which
the
electric
field
is
not
imposed
on
the
dielectric
in
a
stripline
configuration
can
give
misleading
values
of
effective
stripline
permittivity
and
loss
tangent.
This
test
method
measures
an
effective
stripline
permittivity
when
the
specimen
configuration
is
close
to
that
of
the
application.
10
.0
References
1
.
Electrical
Performance
of
Microwave
Boards,
IEEE
Trans.
Components,
Packaging
&
Manufacturing
Technology,
Part
B,
vol.
18,
no.
7,
Traut,
G.
R,
Feb.
1995.
2.
The
Complex
Permittivity
of
RF
Circuit
Board
Materials
by
Resonances
of
a
Stripline
Section
in
the
0.2
to
15
GHZ
Range,
Traut,
G.
Robert,
Preprints
of
the
Measurement
Science
Conference
1997
January
23
&
24,
Pasadena
Convention
Center,
Pasadena,
CA
3.
Complex
Permittivity
Over
a
Wide
Frequency
Range
by
Adjustable
Air
Gap
Probing
a
Stripline
Resonator,
Traut,
G.
Robert,
Proceedings
of
the
Technical
Conference,
IPO
Printed
Circuits
Expo,
March
9-13,
1997,
San
Jose
Con¬
vention
Center,
San
Jose,
CA.
4.
The
NIST
60-Millimeter
Diameter
Cylindrical
Cavity
斤
eso-
nator:
Performance
Evaluation
for
Permittivity
Measure¬
ments,
Vanzura,
E.
J.,
Geyer,
R.
G.
and
Janezic,
M.D.,
NIST
Technical
Note
1354,
August
1993,
National
Insti¬
tute
of
Standards
and
Technology,
Boulder,
CO
80303-
3328.
5.
Characteristic
Impedance
of
the
Shielded-Strip
Transmis¬
sion
Line,
Cohn,
S.
B.,
IRE
Trans
MTT,
(July
1954):
pp.
52
-
57.
vacuum.
6.
Problems
而
Strip
Transmission
Lines,
Cohn,
S.
B.,
IRE
Transactions
MTT
3
(March
1955):
pp.
119-126.
Note:
Material in this Test Methods Manual was voluntarily established by Technical Committees of IPC. This material is advisory only
and its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this
material. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement.
Equipment referenced is for the convenience of the user and does not imply endorsement by IPC.
Page 1 of 23
r
ASSOCIATION
CONNECTING
/
ELECTRONICS
INDUSTRIES
®
221
5
Sanders
Road
Northbrook,
IL
60062-6135
IPC-TM-650
TEST
METHODS
MANUAL
1
Scope
This
document
describes
time
domain
reflectom-
etry
(TDR)
methods
for
measuring
and
calculating
the
charac¬
teristic
impedance,
Zo,
of
a
transmission
line
on
a
printed
cir¬
cuit
board
(PCB).
In
TDR,
a
signal,
usually
a
step
pulse,
is
injected
onto
a
transmission
line
and
the
Zo
of
the
transmis¬
sion
line
is
determined
from
the
amplitude
of
the
pulse
reflected
at
the
TDR/transmission
line
interface.
The
incident
step
and
the
time
delayed
reflected
step
are
superimposed
at
the
point
of
measurement
to
produce
a
voltage
versus
time
waveform.
This
waveform
is
the
TDR
waveform
and
contains
information
on
the
Zo
of
the
transmission
line
connected
to
the
TDR
unit.
The
signals
used
in
the
TDR
system
are
actually
rect¬
angular
pulses
but,
because
the
duration
of
the
TDR
wave¬
form
is
much
less
than
pulse
duration,
the
TDR
pulse
appears
to
be
a
step.
1.1
Applicability
The
observed
voltage
or
reflection
coeffi¬
cient
change
in
the
TDR
waveform
is
related
to
the
difference
between
Zo
of
the
transmission
line
and
the
impedance
of
the
TDR.
If
the
impedance
of
the
TDR
unit
is
known
via
proper
calibration,
then
the
Zo
of
the
transmission
line
attached
to
the
TDR
unit
may
be
determined.
Thus,
the
TDR
method
is
use¬
ful
for
measuring
Zo
and
changes
in
Zo
of
a
transmission
line.
These
impedance
values
thus
determined
can
be
used
to
verify
transmission
line
design
(engineering
development),
measure
production
repeatability,
and
qualify
manufacturers
via
transfer
or
artifact
standards.
Engineering
development
requires
detailed
information
on
the
electrical
performance
of
prototype
units
to
assure
the
trans¬
mission
line
design
yields
the
expected
performance
charac¬
teristics.
Detailed
laboratory
analysis
of
the
effect
of
variations
in
design
features
expected
in
actual
manufacture
can
be
done
to
assure
the
proposed
design
can
be
manufactured
at
a
useful
quality
level.
1.2
Measurement
System
Limitations
Measurements
of
Zo
often
vary
greatly,
depending
on
equipment
used
and
how
the
tests
were
performed.
Following
a
specified
method
helps
assure
accurate
and
consistent
results.
Both
single-ended
and
differential
line
measurements
have
limitations
in
com¬
mon,
including
the
following:
a.
The
Zo
measured
units
are
derived
and
not
directly
mea¬
sured.
Number
2.5.5.7
Subject
Characteristic
Impedance
of
Lines
on
Printed
Boards
by
TDR
Date
Revision
03/04
A
Originating
Task
Group
TDR
Test
Method
Task
Group
(D-24a)
b.
The
value
of
characteristic
impedance
obtained
from
TDR
measurements
is
traceable
to
a
national
metrology
insti¬
tute,
such
as
the
National
Institute
of
Standards
and
Tech¬
nology
(NIST),
through
coaxial
air
line
standards.
The
char¬
acteristic
impedance
of
these
transmission
line
standards
is
calculated
from
their
measured
dimensional
and
material
parameters.
c.
A
variety
of
methods
for
TDR
measurements
each
have
different
accuracies
and
repeatabilities.
d.
If
the
nominal
impedance
of
the
line(s)
being
measured
is
significantly
different
from
the
nominal
impedance
of
the
measurement
system
(typically
50
Q),
the
accuracy
and
repeatability
of
the
measured
numerical
valued
will
be
degraded.
The
greater
the
difference
between
the
nominal
impedance
of
the
line
being
measured
and
50
Q,
the
less
reliable
the
numerical
value
of
the
measured
impedance
will
be.
e.
Measurement
variation
(repeatability,
reproducibility)
may
only
be
a
small
component
of
the
total
uncertainty
in
the
value
of
the
characteristic
impedance.
For
example,
if
the
uncertainty
in
the
characteristic
impedance
of
the
reference
air
line
is
±
0.5
Q
(for
a
95
%
confidence
interval),
then
the
uncertainty
in
the
measured
characteristic
impedance
of
the
test
line
can
be
no
better
than
土
0.5
Q
even
if
measure¬
ment
variation
is
much
less.
f.
The
particular
TDR
methods
described
herein
are
not
suited
for
measuring
the
characteristic
impedance
as
a
function
of
position
along
the
transmission
line
(impedance
profiling)
because
signal
reflections
within
the
transmission
line
under
test
and
between
the
TDR
unit
and
transmission
line
under
test
may
adversely
affect
measurement
results.
g.
The
requirements
for
the
length
of
the
transmission
line
under
test
given
in
Section
3
of
this
test
method
as
well
the
IPC-2141
must
be
met.
Further
measurement
considerations
and
notes
are
provided
in
Section
6.
1
.3
Sample
Limitations
The
type
of
test
sample
used
may
also
impact
Zo
values
(see
IPC-2141).
The
sample-based
limi¬
tations
include:
IPC-2141
IPC-TM-650
IPC-TM-650
Page 2 of 23
Number
2.5.5.7
Subject
Characteristic
Impedance
of
Lines
on
Printed
Boards
by
TDR
Date
03/04
Revision
A
a.
The
transmission
line
under
test
varies
along
its
length
whereas
the
value
ofZo
obtained
assumes
a
uniform
trans¬
mission
line.
Therefore,
the
measured
Zo
only
approxi¬
mates
the
characteristic
impedance
of
an
ideal
line
that
is
representative
of
the
line
under
test.
b.
Lines
on
a
printed
circuit
board
may
deviate
significantly
from
design.
For
example,
microstrip
lines
longer
than
15
cm
[5.91
in]
on
boards
with
plated-through
holes
often
have
variations
in
line
width;
this
variation
is
due
to
plating
and/or
etching
variations.
c.
If
the
transmission
line
is
too
short,
the
accuracy
of
the
cal¬
culated
impedance
value
may
be
degraded
(see
4.1.2).
If
the
transmission
line
is
too
long,
skin
effect
and
dielectric
loss
may
cause
a
bias
in
the
impedance
measurement.
d.
Depending
on
where
the
measurements
are
made,
the
value
of
Zo
obtained
may
be
affected
by
dielectric
and
conductor
loss
and
other
effects.
The
farther
away
from
the
interface
between
the
probe
and
the
transmission
line
under
test,
the
worse
these
effects
will
be.
e.
Duration
of
the
measurement
window
(waveform
epoch)
may
need
to
be
adjusted
for
sample
length
and
location
of
midpoint
vias
along
the
transmission
line.
2
Reference/Applicable
Documents
Controlled
Impedance
Circuit
Boards
and
High
Speed
Logic
Design
IPC
Test
Methods
Manual
1
.9
Measurement
Precision
Estimation
for
Variables
Data
3
Test
Specimens
The
test
specimen
can
take
one
of
sev¬
eral
forms,
depending
on
the
application,
but
contains
at
least
one
transmission
(or
interconnect)
test
structure.
As
examples,
four
types
are
mentioned
in
3.1
.1
through
3.1
.4.
The
transmission
lines
to
be
measured
may
be
of
either
strip¬
line
or
microstrip
construction
and
configured
as
either
single-
ended
or
differential.
See
IPC-2141
for
a
recommended
test
coupon
design.
3.1
Test
Specimen
Examples
3.1.1
Example
1
Representative
samples
of
the
actual
PCB
being
manufactured
are
selected.
In
some
cases,
this
sample
set
may
contain
all
of
the
boards.
Agreed
upon
func¬
tional
or
nonfunctional
transmission
lines
within
the
sample
are
used
for
the
measurement.
Criteria
for
selection
of
such
lines
includes:
a.
Inclusion
of
the
PCB's
critical
features.
b.
Accessibility
of
terminations
for
the
line.
c.
Absence
of
branching.
d.
Absence
of
impedance
changes
within
the
transmission
line
under
test.
e.
Representation
of
controlled
Zo
signal
layers
in
a
multi-layer
board.
3.1.2
Example
2
Representative
samples
should
be
as
in
3.1
.1
,
except
that
the
test
lines
are
nonfunctional
lines
designed
into
the
board
for
easy
termination
for
TDR
mea¬
surements.
Such
test
lines
should
be
planned
to
include
criti¬
cal
features
typical
of
functional
lines
and
should
lie
in
con¬
trolled
Zo
signal
layers.
3.1.3
Example
3
Representative
samples
should
be
as
in
3.1
.1
,
except
test
coupons
are
cut
from
the
master
board
at
the
time
the
individual
PCBs
are
separated.
Such
test
cou¬
pons
will
have
one
or
more
sample
transmission
lines
with
termination
suited
for
testing.
Such
test
lines
should
include
critical
features
typical
of
functional
lines
and
will
be
fabricated
in
the
same
configuration
and
structure
as
the
master
board
on
the
same
controlled
Zo
layers.
3.1.4
Example
4
A
sample
of
the
substrate
laminate
to
be
characterized
before
use
in
manufacturing
PCBs
is
fabricated
with
test
transmission
lines.
The
fabrication
may
involve
lami¬
nating
several
board
layers
together
in
the
same
manner
anticipated
for
PCB
manufacture.
3.2
Identification
of
Test
Specimen
For
specimens
of
types
called
out
in
3.1.1
,
3.1
.2,
or
3.1
.3,
a
board
serial
num¬
ber,
part
number,
and
date
code
should
be
adequate.
Speci¬
mens
from
3.1
.4
should
include
whatever
lot
or
panel
identifi¬
cation
is
available
for
the
substrate
laminate
being
evaluated.
3.3
Conditioning
If
conditioning
is
required,
test
speci¬
mens
shall
be
stored
before
testing
at
23
(+1/-5)
[73.4
°F
(+
1
.8/-0
°F)]
and
50
%
RH
±
5
%
RH
for
no
less
than
16
hours.
If
a
different
conditioning
procedure
is
used,
it
must
be
specified
by
the
user.
4
Equipment
and
Instrumentation
The
TDR
measure¬
ment
system
contains
a
step
generator,
a
high-speed
sam¬
pling
oscilloscope,
and
all
the
necessary
accessories
for
con¬
necting
the
TDR
unit
to
the
device
under
test.
IPC-2141
provides
a
short
discussion
of
the
TDR
system
architecture,
system
considerations,
and
the
TDR
measurement
process.