Fuzz Buttons®

Fuzz Buttons® are a high performance proprietary trademarked contact pin available only
from
Custom Interconnects.  Fuzz Buttons® offer superior value to other contact technologies
such as Pogo Pins, Spring Probes, Hyberboloid contacts or even soldering.  This becomes
especially evident when requirements such as low signal distortion, high frequency, low
insertion force, planarity, shock/vibration resistance, weight and/or extended life come into play.
Fuzz Buttons® are available in a wide variety of diameters and lengths, with diameters ranging
from .010" to .500" and lengths ranging from .040" to as long as .500".   
Most Fuzz Buttons® we manufacture are intended to address fine pitch contact requirements at
the .5mm or 1mm level, but we also can serve applications with as small as .4mm pitch.  Fuzz
Buttons® can mate to virtually any packaging type used in the market today - including BGA,,
LGA, PGA, CGA, QFN and MCM, as well as any custom packaging that a customer may be
employing.  This makes them ideal for use in PCB/PWB interposers, connectors, Test Sockets
and chip packaging - especially as high frequency interconnects or high frequency contacts.
We also manufacture many large format Fuzz Buttons® that can resemble cylinders, slugs,
discs, doughnuts and washers.  These are typically utilized for specialized EMI Shielding and/or
for compliant high current capable ground pads.  It is also possible to lay small or large Fuzz
Buttons® on their sides individually or in an end-to-end configuration to emulate a compliant
EMI "bead" or to make a long X-axis or Y-axis connection.

History
Fuzz Buttons® were first introduced to the electronics marketplace in 1959 and were mainly
used in grounding applications.  A later example includes their use as static dissipation pads
for IBM computer chassis in the 1980s.  Additional customers and applications began to
emerge as Fuzz Buttons® gained popularity in the marketas a highly flexible interconnect
design solution.  Soon the military sector took notice and began to utilize them in shock-
resistant PCB connectors for missile and satellites.  In the early 1990s, Fuzz Buttons were
miniaturized to address the growing semiconductor test market.  Fuzz Button test sockets were
highly regarded by customers such as Qualcomm, AMD and Texas Instruments, when low
signal distortion was especially important during development testing, but also for the high
mating cycles required for production testing.
Today Fuzz Buttons® still serve the military and commercial markets in many surprising
applications.  You will find them in weaponry, satellites, space probes, aircraft, test floors,
laboratories, radar arrays, antennas, supercomputers, crash test dummies, automotive
production, communications and even packaged inside high-end RF products such as
attenuators and amplifiers.

Making a Fuzz Button®
Fuzz Buttons® are a simple, yet elegant structure - whereby, the signal element and the spring
are one and the same.  There are no other moving parts that can cause failure or degrade
signal integrity, the Fuzz Button® is the direct mating point.
They are manufactured from a long strand of highly specialized very fine wire (often as fine as
human hair) that offers high levels of conductivity, strength and oxidation resistance.  There are
several wire material types available, most are Gold-plated, primarily for the properties of
conductivity and prevention of oxidation.
A very thin Nickel flash ensures superior Gold-plating
adhesion.
The most common wire materials used are either a Gold-plated Beryllium Copper
alloy (Au/BeCu) or a Gold-plated Molybdenum (Au/Mo).  While Au/BeCu offers the lowest signal
distortion levels and high mating cycle repeatability, Au/Mo is utilized commonly also because of
its high level of structural stability at temperature extremes.
Fuzz Buttons® are also available in specialty high temp materials, such as Gold-plated
Tungsten (Au/W) or Gold-plated Nickel Chromium (Au/NiCr).  These are used in special cases -
such as operating states at extremely high current or space-qualified temperature ranges.
Fuzz Buttons® are fashioned from these wires using a highly-guarded process that forms them
into individual units of certain diameter and length specs.  The manufacturing process causes
the wire to be randomized throughout the Fuzz Button® structure.
This randomization results in some very desirable effects, such as
  • Preventing internal inductance that otherwise forms from a coiled spring configuration
  • Reduced signal path length and skin effect levels
  • Increasing the overall structural integrity and strength of the Fuzz Button®
  • Creating multiple points of contact within the Fuzz Button® itself, a built-in "redundancy"

Fuzz Button® Specs
Applications: LGA, BGA, PGA, CGA, QFN and more
Pitch Capability: .4mm and above
Compliance/Travel: 15 - 30% of length / 20% nominal
Compression Force: 34 grams
Current Capability: 5 Amps Continuous
Operating Temperature: -60°C to 150°C
Mating Cycles: Fuzz Buttons alone up to 5000 cycles/ with Hardhats up to 500,000 cycles
Frequency Capability: to 40 GHz in natural state, to 100 GHz with design optimization
Cross Talk/Bandwidth: -20dB@10Ghz
Insertion Loss S21: -1dB@26GHz
Return Loss S11: -20dB@10GHz
Inductance: 0.19nH Self / 0.03nH Mutual
Capacitance: 0.16pF Ground / 0.008pF Mutual
Resistance: <10mΩ
Rise/Fall TIme: 50ps / 50ps
Note: Representative values above are for .020" diameter/1mm Pitch, see Technical Data
page for more information on other configurations.

Contact Technology Comparison
Fuzz Buttons® ...Making Connections


Custom Interconnects, LLC
7790 E. Arapahoe Rd, Suite 250
Centennial, CO  80112
Phone: 303.934.6600
Fax: 303.934.6606
Email:
sales@custominterconnects.com
Click here for Fuzz Button Datasheet
For Fuzz Button® Datasheet,
please click on the picture below:
Technology
Areas of Consideration
Pogo Pins
The signal travels on the outside of the structure,
increasing signal path length and distortion. Many
component parts mean more points of potential failure.
Spring Probes
Known to be a somewhat expensive approach.  Often
a longer contact height than is optimal.  Have a very
complex structure meaning more potential points of
failure.
Hyperboloid SuperButton®
Challenging to assemble into carriers.  Component
wires sometimes separate from body during usage.  
Size is limited to larger pitch/pad configurations.  Not
intended for high mating cycle applications.
CIN:APSE®
The annealed wire structure often  limits mating
cycles. Only offered in a single material choice which
limits possible applications.  Have just two diameter
choices which limits pitch/pad matching.
Solder
Fragile in harsh environments such as shock,
vibration and high temperatures, prone to cracking.  
Precision placement equipment is very expensive.  
Very difficult to remove for part replacement.  Often not
RoHS compliant due to lead content contamination..
Fuzz Buttons®
Signal travels via shortest path within the Fuzz Button®
structure; diminishing distortion, resistance and
inductance.  Simple single piece architecture means a
more reliable contact.  When used in conjunction with
Hardhats, high mating cycles can be achieved with
little signal degradation.  Always Lead-Free and RoHS.
Small Format Fuzz Buttons®
Applications: PCB Interposers, Device
Interposers, Production Sockets, Test
Sockets, Connectors, RF / Coaxial
Interconnects, compliant grounding/shorting
plates and internal packaging grounds.
Large Format Fuzz Buttons®
Applications: Compliant grounding,
specialized EMI Shielding and as Static
Dissipation Pads.
Fuzz Button® Part Numbering

WW-DDDLLL

WW = Wire Type
DDD = Diameter (in inches)
LLL = Length (in inches)

Wire Types
80 = Au/BeCu (Gold-plated Beryllium Copper)
Most commonly used due to best S-parameters,
lowest resistance values

81 = Au/Mo (Gold-plated Molybdenum)
Excellent dimensional stability

82 = Au/W (Gold-plated Tungsten)
Higher temperature but at premium cost

83 = Au/NiCr (Gold-plated Nickel Chromium)
High temperature, low resistance, premium cost

For custom wire, please contact factory

Diameters
.010", .015", .020", .025", .030", .040", .045", .050",
.062", .075", .080", .090", .125", .
150", .170", .200",
.280"
For custom diameters, please contact factory

Lengths
Available ranges shown for each diameter
.010" = .040" to .080"
.015" = .040" to .110"
.020" = .040" to .200"
.025" = .040" to .200"
.030" = .030" to .250"
.040" = .040" to .250"
.045" = .045" to .250"
.050" = .050" to .250"
.062" = .062" to .300"
.075" = .075" to .300"
.080" = .080" to .300"
.090" = .090" to .400"
.125" = .060" to .400"
.150" = .060" to .500"
.170" = .060" to .500"
.200" = .060" to .500"
.280" = .060" to .500"
For custom lengths, please contact factory

Fill Rate
.010" and .015" diameters = 38%
.020" and greater diameters = 25%
For custom fill rate, please contact factory

Tolerances
Diameter +/-5% (exceptions are .010"/.015" dia)
Length +20/-0%
Fill +/-2%
For custom tolerances, please contact factory
Tolerances are measured in the free,
uncompressed state and measurements are
made using the main structural elements.  What
counts most is AFTER the Fuzz Button® has been
compressed during usage, whereby the amount
of material filling the holes remains very
consistent across the array.  Secondly, Fuzz
Buttons® have a large range of acceptable travel
and compliance, they can solve many stackup
tolerance and board/packaging planarity issues.