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Soldiers Travel Lighter With
Spring/Probe
Connector Design Advancements
By David Impett, Product
Manager, ITT Interconnect
Solutions
 Harsh
environment and mission-critical
systems require connector
solutions that deliver superior
performance, reliability, and
durability. Technology
trends in military applications
also call for highly dependable
materials, reduced size and
weight, and greater
functionality. Spring/probe
connectors meet these needs
well, and we now see these
systems deployed in a variety of
modern military and “future
soldier” applications, such as
sophisticated command, control,
communication, computer, and
intelligence (C4I)
systems. Rugged spring/probe
interconnects offer a
high-density signal packaging
approach within a confined
space, enabling soldiers to
become more mobile and their
advanced equipment to become
more portable.
Materials
Military and defense
applications require component
solutions that are highly
reliable, as there is no room
for in-field failure.
Material selection is critical
for applications that experience
shock, vibration, high pressure,
and/or extreme temperatures. But
current interconnects currently
available do not offer design
engineers a solution that
increases signal functionality
while meeting confined size
constraints, high-temperature
requirements, and sealing
ratings necessary for today’s
military applications. Plastic
connectors, even those with
metalized plating, are unable to
meet the military’s reliability
and performance standards.
Connector shells made of
stainless steel material meet
stringent requirements for
corrosion resistance under
MIL-spec “P”-grade standards,
while at the same time meeting
JEDEC standards for RoHS
compliance. Other connector
designs are constructed with
high-temperature LCP dielectric
materials, which allow them to
be employed in applications with
temperatures as high as 200°C,
such as military vehicles and
space and avionics.
While materials such as
stainless steel are highly
reliable, they affect a
connector’s weight. Soldiers
often carry gear weighing in
excess of 100 lbs, so
components for soldier
applications need to be
extremely robust, yet as
lightweight and small as
possible. These are conflicting
demands — robustness often
requires the use of stainless
steel, as it is extremely
durable and allows for a
significant number of mating and unmating cycles; however, it’s
not lightweight. Manganese is
also an option in terms of
robustness, but it is more
expensive. Stainless steel is
typically implemented due to its
robustness, but the additional
weight is a burden to soldiers.
Size and
Weight
In terms of size, spring/probe
contact spacing as low as
0.635mm provides high-signal
density in minimal space,
whereas other designs feature
size 23 pin-and-socket contacts
that have the equivalent
electrical performance of size
22 contacts, reducing contact
spacing to as little as 0.193mm.
In some designs, the use of size
23 contacts for the
interconnection of the cable
also allows for the use of less
stainless steel, thus decreasing
both cost and weight.
Future
Soldiers
Designed for
“future soldier” applications,
highly reliable pogo pin/pad and
quick breakaway technologies
provide a “ripaway” decoupling
action for rugged, wearable
military communications
equipment that requires
interconnects that combine
power, data, and audio. This
spring/probe connector
technology increases the number
of mating cycles and enables the
connectors to be cleaned in the
field. In addition, the
lightweight, small form factor
design offers significant space
savings for handheld devices.
ITT’s Nemesis Series, for
example, incorporates a simple
push/pull mating mechanism to
mate and un-mate the connector
system quickly. The connector’s
“blind mating” ability provides
reliable and fast connection
without the need for visual or
mechanical keying. The internal
clip mechanism also maintains
constant connection with the
contact itself, reducing
electrical resistance and
accommodating misalignment
issues. The typical pull force
is five to eight pounds, but may
be adjusted based on specific
connector design considerations.
The patented breakaway pogo pin
contact technology guarantees
more than 10,000 mating cycles.
The pogo pin/pad connectors are
fully sealed in the unmated
state (watertight to over 20m)
and weigh less than 25g, which
is critical for on-soldier
applications. The unique spring
probe system allows the
connector receptacle to house
individual touch-pad contact
areas. This design allows for a
very effective electrical
engagement point of contact.
Further, the spring probe
contact system and touch pads
allow for easy cleaning in the
field, where dirt, moisture,
mud, sand, and other
contaminants may be present. The
individual touch-pad contacts
have no crevices for
contaminants to accumulate, a
desirable feature in harsh
environment field conditions.
Standard termination options
include PCB tails, solder cups,
and pin contacts.
The miniature pogo pin/pad
circular connectors provide full
360-degree EMI shielding and are
fully sealed to IP67/IP68
specifications for harsh
environments, such as C4I
(command, control,
communications, computer, and
intelligence) military
equipment. In addition, the
rugged stainless steel
construction provides
durability, while an enhanced
strain relief design eliminates
cable overstressing.
Anti-reflective salt
spray-resistant plating on the
connector shells protects the
vital cable interface and
assists soldier camouflage in
marine environment maneuvers,
while the seamless ribbed
overmolding provides a non-slip
grip in damp conditions.
The number of contact positions
range from 4 through 48. The
shells for these mini circulars
are manufactured using either
aluminum or stainless steel with
nickel plating. These materials
exhibit superior mechanical
performance properties under
extreme environments. Multiple
keyway options are incorporated
into this interconnect family
and prevent any instance of
mismating.
 Inserts
for breakaway connectors utilize
high-grade thermoplastics such
as PEEK or PPS dielectric
materials. Using innovative mold
tool designs, the connectors
provide very tight tolerance
insert packages. The tight pitch
contact spacing may address
pitches ranging from 0.050 to
0.085. Special pitch
configurations may be
accommodated, pending pin count
and electrical performance
requirements. The ITT tight
pitch contact spacing allows for
the highest density electrical
signal package possible in a
very confined space. Tight
tolerances allow for higher
reliability interconnects,
manufactured within a
cost-effective system design.
Compared with the nearest
equivalent
MIL-DTL-38999
connectors,
pogo pin/pad connectors are
50% lighter, 60% smaller, and
100% sealed, all requirements
for soldier modernization
programs.
Today’s military electronic
system designers are challenged
to create electronic systems
that perform well in the most
extreme harsh environments.
Furthermore, these systems must
also be smaller and lighter. Not
only must designers ensure that
their system modules (LRM) and
boxes perform in demanding
elements, they must ensure that
the interconnect link for their
systems survive and maintain
signal fidelity. Electronic
interconnects designed and
integrated into electronic
equipment for harsh conditions
must be able to withstand severe
shock, vibration, and thermal
dynamics.
The spring probe contact
connectors offer the highest
reliability for interconnects
challenged to meet the toughest
performance standards in harsh
environments. The pogo pin/pad
spring/probe contact/connector
systems have been tested through
extensive military and
customer-specific test programs
to ensure that design and
manufacturability features have
indeed met all reliability and
field performance requirements.
Designed and manufactured to
exceed various thermal shock,
vibration, random shock, and
signal performance spectrums,
the pogo pin/pad is one of the
technologies of choice in
military electronic systems.
David Impett is a product
manager at ITT Interconnect
Solutions. He can be reached at
david.impett@uk.itt.com. |
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