MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第524页

MIL-STD-883F METHOD 3017 29 May 1987 2 3.2 Test proc edure for pac kage t ransmi ssi on charac teri sti cs. Using a s ect ion of c oaxial cable of known, c alibr ated charac teri sti c im pedance (Z Ref ) as a r eferenc …

100%1 / 708
MIL-STD-883F
METHOD 3017
29 May 1987
1
METHOD 3017
MICROELECTRONICS PACKAGE DIGITAL SIGNAL TRANSMISSION
1. PURPOSE
. This method establishes the means of evaluating the characteristic impedance, capacitance, and delay
time of signal lines in packages used for high frequency digital integrated circuits. It is intended to assure a match between
circuit performance and interconnecting wiring to minimize signal degradation.
1.1 Definitions
.
1.1.1 Characteristic impedance
. The impedance that a section of transmission line exhibits due to its ratio of resistance
and inductance to capacitance.
1.1.2 Delay time
. The time delay experienced when a pulse generated by a driver with a particular drive impedance is
propagated through a section of transmission line.
1.2 Symbols
.
R: Resistance
L: Inductance
C: Capacitance
t
pd
: Propagation delay time
2. APPARATUS
. The approaches for transmission performance measurements shall include a suitable time domain
reflectometer (TDR) (see 2.1) and dc resistance measuring equipment (see 2.2).
2.1 Time domain reflectometer
. The TDR used for this test shall have a system rise time for the displayed reflection that
is not less than 5 times and preferably 10 times the rise time (method 3004) for the candidate integrated circuits to be
packaged. Interconnecting cables and fixtures shall be designed such that this ratio is not degraded due to reflections and
ringing in the test setup.
2.2 DC resistance
. DC resistance measuring equipment and probe fixtures shall be capable of measuring the resistance
of the package leads and the chip-to- package interconnect media with an accurancy of no greater than ±10 percent of the
actual value including errors due to the mechanical probing interface contact resistance.
3. PROCEDURE
. The test equipment configuration shall be as shown on figure 3017-1 using a time domain
reflectometer as specified (see 2). The characteristic impedance (Z
o
), propagation time (t
pd
), resistance and load
capacitance (C
L
) shall be measured for all representative configurations as determined by a review of the package drawings,
and the intended applications (see 3.2 through 3.3).
3.1 General considerations
.
3.1.1 TDR measurements
. Accurate measurement of transmission performance of a package pin using a TDR requires
careful design and implementation of adapter fixtures to avoid reflections due to transmission line discontinuities in the
cables and junctions between the TDR and the package being tested. The accuracy of the measurement will be enhanced if
the coaxial cable used to interface to the package is of a characteristic impedance as close as possible to the package pin
impedance. The interface to the package should be a soldered connection and mechanical design of the actual
coax-to-package interface should minimize the length of the uncontrolled impedance section. Stripline interfaces are the
best method for surface mount package styles.
3.1.2 Test configurations
. Obtaining a good high frequency ground is also important. Connection of the package ground
plane (if the package design has one) to the test set-up ground plane should be accomplished with a pin configuration
similar to actual usage in the intended package applications.
Pin selection for testing may vary according to package complexity. For packages with very symmetrical pin configurations
only a few pins need be tested but configurations must include pins adjacent and nonadjacent to the ground pins. Packages
with complex wiring and interconnection media should be tested 100 percent.
MIL-STD-883F
METHOD 3017
29 May 1987
2
3.2 Test procedure for package transmission characteristics. Using a section of coaxial cable of known, calibrated
characteristic impedance (Z
Ref
) as a reference measure the minimum (Z
Min
) maximum (Z
Max
) and average (Z
o
) values of
reflection coefficient (
ρ) for the section of line on the TDR display that has been carefully determined to be the package pin
(locate using zero-length short circuits).
3.2.1 Characteristic impedance
. Calculate characteristic impedance (Z
o
) for each of the cases from the formula:
0Ref
Z
=
Z
x
(1+ )
(1- )
ρ
ρ
3.2.2 Delay time measurement
. From the TDR display of 3.2.1 measure the time difference in picoseconds from the point
identified as the start of the exterior package pin (t
1
) to the chip interface point (t
2
) (t = t
1
-t
2
)
Form the package design drawings, determine the physical length of the package run (L)
Time delay
t
=
t
L
pd
∆
3.2.3 Load capacitance calculation
.
Load capacitance
C
=
t
Z
L
pd
o
3.2.4 Load inductance calculation
.
Load inductance (series) =
(
t
)
C
pd
2
L
3.3. Series resistance measurement
.
Using the test setups of figure 3017-2, separately measure the dc resistance of the chip-to-package interface media (R
M
)
and the package lead (R
L
).
4. SUMMARY
. The following details, when applicable, shall be specified in the applicable acquisition document:
a. Z
Max
.
b. Z
Min
.
c. Z
o
(max).
d. Z
o
(min).
e. t
pd
(max).
f. t
pd
(min).
g. C
L
(max).
*
MIL-STD-883F
METHOD 3017
29 May 1987
3
h. C
L
(min).
i. L
L
(max).
j. L
L
(min).
k. R
M
(max).
l. R
M
(min).
m. R
L
(max).
n. R
L
(min).
o. Package pins to be tested.
p. Package ground configuration.