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VHDM® FAQs
Electrical
Mechanical
Electrical
What is the current rating
of the signal pins?
1 amp
What is the current rating
of the shields?
3 amps for the 8-row; 2 amps for the 6-row
What is the current rating
of the power blade?
10 amps/blade. 30 amps total for an 8-row module; 20 amps
for the 6-row module
Can the guide pins be used for
first-mate ground?
A unique grounded guide module and mating guide pin are now
available
What is meant by the term
'real' signal pins?
The maximum number of pins usable for signal transmission
while providing less than 5% backward and forward crosstalk,
and less than 5% reflection at the desired risetime.
What electrical models
are available for VHDM connectors?
Both 6-row and 8-row single-line and multi-line simulation
models.
What is the difference in the
bulk resistance between the 'A' row and the 'H' row contacts
(for the 8-row version)?
8 to 10 milliohms
At what risetime do I have to consider
grounding some of my signal pins?
Below 250 picoseconds (single-ended) and 200 picoseconds (differential-pair).
Performance for other patterns is available.
What is the contact resistance
between the compliant pin and the plated-through hole?
1 milliohm, maximum.
Are there unique connector
options for running differential architecture?
Yes. The VHDM product family has both an 8-row differential-pair
configuration as well as a new 5-row differential-pair version.
These are identified as VHDM-HSD (high-speed-differential)
derivatives.
Mechanical
What is the per-pin insertion/mating
force?
40 grams per signal and 40 grams per each beam on the backplane
shield
What is the
normal force per contact beam?
60 grams per contact beam and 60 grams per contact point on
the backplane shield
What mating forces should
I expect with the 8-row?
Approximately 16 pounds per linear inch of connector.
What kind of compliant press-in
forces should I expect with the 8-row?
750 pounds per inch (backplane and daughterboard)
Do the 6-row and 8-row connectors
share the same datum on the daughterboard?
No. They were independently designed to ensure minimal noise
and delay.
How much wipe under load do I get with
the 4.75mm-long signal pin?
0.068" (1,5mm) minimum.
How long can my daughtercard
connector assembly be before I need to split it and use a
joiner module?
Over 304mm (12 inches) long.
Do I have to use end-caps or guide
pins in my configuration?
End caps must be used in a connector pattern that does not
have power or guide modules at the ends. This is done in order
to cover up the exposed metal on the wafer. Guide pins are
strongly recommended at both ends, with a design guideline
of one guide module minimum for assemblies under 150mm (six
inches) long, and two guide modules for assemblies 150mm and
longer.
The daughtercard connector is
press-fit. Do I still need screws through my daughtercard?
Yes, for joiners and guide modules.
The connector does not look
symmetrical. Do I need special right-hand and left-hand polarizing/guidance
modules on the backplane?
Yes. There are right-hand and left-hand polarizing/guidance
modules for the 6-row and 8-row 10- and 25-column backplane
shrouds.
What is the minimum card-slot
pitch for the 6-row and 8-row connectors?
18mm for the 6-row and 22mm for the 8-row. See the customer-use
drawings for board offset.
How long are the press-fit tails?
0.110" (2,79mm) long.
What are the minimum and
maximum printed board thicknesses required for VHDM connectors?
0.070" (1,78mm) minimum. There really is no stated maximum
since the board fabricator is restricted by the manufacturing
aspect ratio for the daughterboard & backplane.
Will there be a different drilled
and finished hole specification for the different surface
finishes that we want to use?
Yes. For finishes of Bare Copper with OSP, Immersion Silver,
Immersion Tin, Tin-Lead and Nickel-Gold, the drill size is
0.026" (# 71 Drill) and the finished hole size is 0,61mm
(0.024") - 0,51mm (0.020"). For Hot Air Solder Level
finishes (HASL) the drill size is 0.026" (#71 Drill)
with a finished hole size of 0,61mm (0.024")
to 0,495mm (0.195").
What product verification testing
is available?
Full characterization testing is listed in Teradyne's Technical
Bulletin TB2033 which can be found in the Technical
Bulletin section of this site. Testing includes: Central
Office Bellcore Testing per GR-1217-CORE; internal signal
integrity characterization and process verification.
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