IPC-TM-650 EN 2022 试验方法-- - 第533页
IPC-TM-650 Number Subject Date Revision Page 2 of 2 2.5.27 Surface Insulation Resistance of Raw Printed Wiring Board Material 3/79 5.2.5 After allowing the meter to "charge” for 60 seconds, switch to "measure” …
4.4.11 TDR ESD Protection
TDR equipment pro-
vide ESD protection commensurate with the test environment.
It is recommended that samples be grounded to remove any
residual static to protect against static discharge with in the
test environments.
Static can be built up on samples prior to test and can dam-
age the sampling heads in the TDR/TDT equipment. There-
fore, it is recommended that ESD protection be used. Such
protection must be supplied internally to the TDR system.
Samples should be grounded to remove any residual static
and/or passed through some type of deionization device prior
to testing. This can be done by shorting each line to ground
with a simple connection between one end of the lines and
the instrument ground. Keeping the relative humidity in the
test area between 45% and 55% may minimize the buildup of
static. Operators are always required to have a grounding
strap around one wrist having a 1 MΩ resistor in series with it.
Special waxing can be used on the lab floor to prevent body
charge build-up. Always use a grounded, conductive table
mat. Always wear a heel strap. Always ground the center con-
ductor of a test cable before making a connection to static-
sensitive equipment.
4.5 SPP Test Apparatus
4.5.1 Other SPP Equipment Requirements
An LCR
meter is required that can measure capacitance at 1 MHz.
4.5.2 SPP Software
The following software is required for
implementation of the SPP technique:
a) Gamma-Z software for signal processing or equivalent
b) 2D field solver such as CZ2D, which can be downloaded
from: www.alphaworks.ibm.com/tech/gammazandcz2d,
or equivalent
4.6 FD Test Apparatus
The measurement equipment
needed includes a VNA, cabling, a probing solution, and a
calibration structure and calibration coefficients that are
acquired from the probe or connector manufacturer. The
probing solution should match the test sample chosen from
the above described samples. High performance connectors
and cables are recommended in performing VNA measure-
ments. Optionally, a TDT system may be used in place of a
VNA to acquire frequency domain attenuation and loss data.
5 Procedures
5.1 EBW Measurements Procedure
5.1.1 Measurement Process
This procedure will measure
the maximum slope of the rise time of the combined measure-
ment system and DUT and determine a loss factor. Recom-
mended resolution is 4000 points with a horizontal scale of
200 ps/div.
Probe the interconnect (see Figure 5-1) and measure
the maximum slope of the step response in Megavolts/second
(e.g., 430 Megavolts/second). The maximum slope may be
directly acquired from TDR equipment with that capability.
Report the Loss Factor at the test system bandwidth
(as measured within 4.4.5.1) (e.g., 430 Megavolts/second @
14.5 GHz).
5.2 RIE Measurement Procedures
Figure 5-2 summa-
rizes the RIE measurement procedure.
The RIE method utilizes a comparison between a reference
loss (line) measurement and a test conductor (line) measure-
ment. The reference measurement may be a calibration stan-
dard or short length of conductor in the neighborhood and on
the same layer as the conductor to be measured.
5.2.1 TDR – Open or Unterminated Line Requirement
The RIE method requires a measurement of lines where one
end is a probe launch and the other end is left unterminated
or open. The probe injects a fast step at the launch point in
much the same manner specified in IPC-TM-650, Method
2.5.5.7. The injected step causes a wave to propagate down
the line; most of the wave is reflected by the open end of the
line and travels back to the source where it is measured as the
superposition of the incident wave and all the reflections.
IPC-25512-5-1
TDR Instrument
probe
SIU
Maximum
risetime
DUT
(interconnect)
Time
Number
2.5.5.12
Subject
Test Methods to Determine the Amount of Signal Loss on
Printed Boards
Date
07/12
Revision
A
IPC-TM-650
—
shall
Step
1
-
Step
2
-
Figure
5-1
Measurement
of
Maximum
Slope
of
Step
Rise
Time
at
Open
end
of
DUT
Page
12
of
24
IPC-TM-650
Number
Subject Date
Revision
Page 2 of 2
2.5.27
Surface
Insulation
Resistance
of
Raw
Printed
Wiring
Board
Material
3/79
5.2.5
After
allowing
the
meter
to
"charge”
for
60
seconds,
switch
to
"measure”
and
read
the
meter
in
megohms
after
the
indicator
settles
down
(usually
within
60
seconds).
5.3
Evaluation
Readings
shall
be
recorded
to
two
signifi¬
cant
digits
in
megohms.
6
Notes
6.1
This
method
can
be
used
in
substitution
for
surface
resistance.
Volume
resistivity
cannot
be
replaced
by
this
method,
but
other
tests
such
as
dielectric
strength,
dissipa¬
tion
factor,
and
dielectric
constant
will
give
a
better
indication
of
the
electrical
properties
than
volume
resistivity.
Figure 1 Resistive Matching Network for Unbalanced Cables
For Z System Z Cable:
Z System
R
1
R
2
For Z System Z Cable:
Z System
Z Cable
R
1
R
2
R =
1
Z (Z - Z )
C
C
S
R = Z
2
(Z - Z )
C
S
S
Z
S
R =
1
Z (Z - Z )
C
R = Z
2
(Z - Z )
C
S
Z
S
Z Cable
S
S
C
IPC-TM-650
Number
Subject Date
Revision
Page 2 of 4
I
PC-2-5-30-1
2.5.30
Balanced
and
Unbalanced
Cable
Attenuation
Measurements
12/87
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