Custom Interconnects

Custom Interconnects, LLC
7790 E. Arapahoe Rd, Suite 250
Centennial, CO  80112
Phone: 303.934.6600
Fax: 303.934.6606
General Design Rules

Universal Applications
1. Contact Pitch for each Fuzz Button diameter:  .010" diameter = .4mm/.5mm,
.015" diameter = .65mm, .020" diameter = .8mm/1mm, .030" diameter = 1.27mm
2. Fuzz Button Compliance/Travel: 15 - 30% of length / 20% nominal
3. Minimum wall spacing between holes = .010"
4. Minimum spacing of hole wall to body edge = .010"
5, Recommended PCB pad plating: Hard gold over electroless nickel, 80 micro-inch gold over
200 micro-inch nickel over 0.5 to 1.0 ounce copper.
6. PCB pads should be larger than Fuzz Button diameter, round or rectangular in shape, with
maximum via size filled.
7. Lead traces are recommended to be buried with the PCB layers. If necessary, traces may
run on top side if covered by solder mask,  which will eliminate shorting.
8. Solder mask must stay a minimum of .002" away from the perimeter of the PCB pads.
9. Recommended PCB minimum thickness is .062".

Interposers with Fuzz Buttons only
1. We recommend the Fuzz Button protrude on either side at .005" to .012" each in the
uncompressed state. This allows for easier alignment while also guarding against  Fuzz
Button "fall-over" causing a short between two adjacent PCB pads. When the interposer is
sandwiched between 2 opposing PCBs, the Fuzz Buttons become flush to the surface plane.
2. Optimal travel for a Fuzz Button is 15 - 30% of its length in the uncompressed state, but
values outside of this range are usually acceptable, especially if only a single mating is
3. The holes in the interposer body should be just slightly larger than the Fuzz Button diameter.
Examples: For .020" Fuzz Button, holes should be .0215" to .0225" (depending on the carrier
thickness), while for a .010" Fuzz Button, the holes should be ~.0110" and for a .015" Fuzz
Button, the holes should be ~.016". This allows for easier insertion while also ensuring the
Fuzz Buttons remains in place during handling and assembly. These numbers are just
guidelines and it is recommended that customers do some local testing since there could be
variations due to carrier material characteristics and thicknesses.
4. To aid insertion of the Fuzz Buttons, we recommend a 45 - 60 degree hole chamfer.
5. Minimum body thickness is .030" which supports the other stated design rules.

Test Sockets & Interposers with Fuzz Buttons & Hardhats
1. The body requires a 2 drill counterbore operation, whereby the bottom hole portion is larger
than the top portion. This ensures the Hardhat shoulder is stopped by the smaller hole
diameter, so the Hardhat does not come out of the top side.
2. The recommended Fuzz Button pre-load on the bottom side is .010", while the Hardhat on
the topside should be designed to protrude by .010" in the uncompressed state. Once
compressed, the Hardhat becomes flush to the surface plane.
3, The minimum recommended Fuzz Button length for this type of stack-up is .060", however, a
length of .080" to .100" would be more ideal to provide greater durability and travel.
Interposer/Socket Material Choices
Ultem® Ultem 1000 is our go-to material offering low out-gassing, superior
isolation, high structural strength and very light weight.
Techtron PPS
Teflon® PTFE
FR4 / G-10
Other dielectric plastics
Aluminum Alloys (many coatings/platings available)
Brass (commonly gold-plated)

RoHS Compliance Statement

Industry Publications and Resources
Microwave Journal
Microwaves & RF
Microwave Product Digest
High Frequency Electronics
Chip Scale Review
Semiconductor Packaging News
Global SMT & Packaging
Electronic Design
Military & Aerospace Electronics
Aerospace & Defense Technology
Tech Briefs
JED - The Journal of Electronic Defense
Intelligent Aerospace
Connector Supplier
Association of Old Crows
Electrical Characterization Data

40GHz RF Test Reports at 50 Ohm Impedance
Fuzz Buttons in a Coaxial Structure
.010" diameter RF Fuzz Buttons only
.020" diameter RF Fuzz Buttons only

40GHz S-Parameter Test Reports at 50 Ohm Impedance
Fuzz Buttons in an Array
.010" diameter .4mm / .5mm pitch Fuzz Buttons only
.020" diameter .8mm / 1mm pitch Fuzz Buttons only

40GHz S-Parameter Test Reports at 50 Ohm Impedance
Fuzz Buttons with Hardhats in an Array
.010" diameter .5mm pitch Fuzz Buttons and Hardhats
.020" diameter 1mm pitch Fuzz Buttons and Hardhats

Legacy 10GHz/30GHz S-Parameter Test Reports
Fuzz Buttons arranged in an Array
.010" diameter / .5mm pitch Fuzz Buttons only
.010" diameter / .5mm pitch Fuzz Buttons and Hardhats
.020" diameter / 1mm pitch Fuzz Buttons only
.020" diameter / 1mm pitch Fuzz Buttons and Hardhats
.030" diameter / 1.27mm pitch Fuzz Buttons only

Resistance & Force vs Deflection Curves

.010 Diameter

.020" Diameter

.030" Diameter

.020" Diameter Au/BeCu Deflection Curve

Current Carrying Capability

.010" Diameter = 2 Amps Continuous
.015" Diameter = 3 Amps Continuous
.020" Diameter = 5 Amps Continuous
.030" Diameter = 6 Amps Continuous

Fuzz Buttons work in DC, UHF, L, C, X, Ku, Ka
and Q Band applications.

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