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Overview
VHDM* (Very High Density Metric)
 The Very High Density Metric (VHDM) connector system is designed for applications that require high interconnect density and high speed signal integrity. It is available in both 6 row and 8 row configurations with ground planes between columns. The grid of the mating face is 2 mm between columns and 2.25 mm between rows. The ground planes are interstitial to the signal grid. Standard VHDM connectors support data rates of 2.5Gb/s with less than 5% crosstalk.
The daughter card connector is made from wafers. Each wafer has a column of signal contacts plus a ground plane. The wafers are then mounted onto a stiffener to make a monoblock connector. The connector can include signal wafers, guide blocks, and power modules.
On the backplane side, headers are available in lengths of 10 and 25 columns. There are open and guide pin versions available. Extremely robust free standing guide pins are also available These are mounted directly into the backplane PCB and can accommodate heavier daughter cards.
For additional information on VHDM products, contact: vhdm@molex.com
Power Strategy
- Power modules
for 8 row connectors can have 3 blades
- Power modules
for 6 row connectors can have 2 blades
- A power module
only occupies 6.00mm (.236") of board edge
- Up to 4 different
mating levels are available for power allowing sequenced mating
during hot swap operations
- All power levels
mate before the signal pins
- Multiple power
modules provide up to 120A per 25.00mm (.984") of board edge
Enable Pin
- A 4.25mm (.167")
mating pin, generally used as a last-mate enable pin, is available.
Please contact Inside Sales if you need this pin length.
Guidance Strategy
- For smaller
connectors on smaller boards, guidepins may not be needed.
- For larger
PCBs, guidepins are recommended - Generally spaced 1/3rd from
each end of the PCB for best guidance.
Spaces In the Connector
- Spaces can
allow a large board stiffener even with low signal density connectors
- Wherever there
is a space, end blocks are recommended (or power or guidance to
act as "book ends" for the stackup of wafers)
- Spaces allow
for more efficient routing of backplanes with clear "highways"
to allow very high speed signals to pass with minimum discontinuity
Mating PIN
lengths
| Signal
Pin |
Pin Length |
Wipe |
| Short Signal |
4.25 (.167) |
1.15 (.045) |
| Medium Signal |
4.75 (.187) |
1.65 (.065) |
| Long Signal |
5.15 (.203) |
2.05 (.070) |
| Extra Long Signal |
6.25 (.246) |
3.15 (.124) |
| Power
Pin |
Pin Length |
Wipe |
| Short Power |
7.50 (.295) |
4.25 (.167) |
| Medium |
9.00 (.354) |
5.75 (.226) |
| Long |
10.50 (.413) |
7.25 (.285) |
| Extra Long |
12.00 (.472) |
8.75 (.344) |
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