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June, 2016
A Solution for Press-Fit Pin and Receptacle Applications
By Stephen Capitelli, Manager of Product Engineering, Mill-Max Mfg.
nents for electrical and electronic applications. As with other types of pins and fasteners, they play an inte- gral role in product quality, but are easily taken for granted. For exam- ple, the fasteners that secure an air- craft’s skin to its airframe are criti- cal, as failure could be catastrophic. The press-fit pins and receptacles designed for interconnect electronic modules are another such example. Electronic circuitry intercon-
P
nected by press-fit pins and recepta- cles is so broad in application that their role in system performance can- not be taken lightly. Mill-Max has approached the design and manufac- ture of press-fit pins and receptacles with an uncompromising attention to detail. Individual pins and recepta- cles can be used for the transmission of signals ranging from logic-level to power and are available in sizes suit- ed to particular form factors.
Press-Fit Applications Pins or receptacles, used individ-
ually or in pairs, are useful when ter- minating single wires to PCBs. Used in groups, press-fit pins and recepta- cles are useful for applications includ- ing daughterboard to motherboard; component, module, or cable to PCB; cable to cable; and in fuses.
Compliant press-fit before and after insertion.
offering multiple advantages over stamped-and-formed connectors. The machined pin technology allows for a seamless construction, which pre- vents contact contamination from wave or reflow soldering. This spe- cialized process enables press-fit geometries, which include triangu- lar, square, hexagonal, and octagonal shapes, to meet the hole size require- ments of specific applications. Lead- in countersinks on the pin recepta- cles aid in the alignment of the pins. The pins and receptacles are
Standard solder tail for interconnect socket.
Applications for the technology
include power, control functions, sig- nal data, and RF. The company takes a special approach to press-fit pins and receptacles by applying preci- sion-machined pin technology —
made of brass alloy for strength, as well as for conductivity and the mate- rial’s thermal properties. A multi-fin- ger beryllium-copper contact clip scores the mating device lead for a gas-tight electrical connection and provides power and force distribution. In addition, a two-piece receptacle construction of a shell and contact clip allows for cost-efficient plating combi- nations and aids the solderability and conductivity of the application. Press-fit pins and receptacles
fall into two distinct categories: those for plated through-holes (solderless press-fit) and those for non-plated through-holes, such as bare PCB holes, plastic housings and insula- tors. Press-fitting makes use of mate-
ress-fit pins and receptacles are among the most versatile types of interconnection compo-
rial displacement, where the pin deforms both the mating hole’s shape and diameter, though one exception is the compliant press-fit pin, as it conforms to the hole size as it is pressed in. Solderless press-fit pins and
receptacles are used in applications where soldering is not reliable or eco- nomical, such as thick PCBs and back- planes. Often, press-fitting is a more efficient manufacturing solution for bringing power or control signals onto SMT boards by cable, discrete wires or a daughter card, board stacking appli- cations, and for adapter boards for footprint translation — useful when a chip is converted from through-hole to an SMT package. When pressed into plated holes
on circuit boards, a properly-sized hole and press-fit will form a gas- tight connection. This kind of connec- tion provides a reliable electrical interface, characterized by stable impedance and no oxidization. Because the applications are so var- ied, the physical configurations of how the pins and receptacles mount and function also vary.
Press-Fit Solutions Mill-Max offers a selection of
press-fit pins and receptacles in many configurations for a broad vari- ety of applications. The company offers a press-fit barb for non-plated through-holes, which is designed for retention purposes in insulators or plastic housings. Also available is a press-fit
knurl for non-plated through-holes. This design has vertical serrations around the diameter of the intercon- nect pin, which provides a retention feature for press-fitting in a non- plated PCB hole or insulator, and also prevents the pin from rotating. Press-fit polygons for plated through- hole are offered to provide a solder- less press-fit interconnect for PCBs. These are especially useful for trou- blesome, hard-to-solder, thick PCBs and backplanes. With the company’s press-fit-
compliant tail for plated through- holes, a drilled and slotted receptacle or pin tail can be pressed into a plat- ed 0.04 in. (1.02 mm), ±0.003 in. (0.076 mm) PCB through-hole. This is useful for mounting an intercon- nect component to a PCB without
Press-fit knurl for non-plated through-holes.
as ±0.0005 in. (0.013 mm), and even tighter if necessary. The company’s pins and recepta-
cles are available in different shapes and configurations to best match the intended application and assembly technique. All are precision-machined, not stamped. This approach allows customers to have the highest degree of flexibility and performance without
paying for tooling costs. Contact: Mill-Max Mfg. Corp.,
190 Pine Hollow Road, Oyster Bay, NY 11771 % 516-922-6000 fax: 516-922-9253 E-mail:
rritter@mill-max.com Web:
www.mill-max.com r
damaging the hole and no post- assembly soldering is required. Finally, Mill-Max offers a press-fit- compliant body for plated through- holes which can be pressed into non- plated or plated through-holes. Sol - der ing is optional for plated through- holes. One important benefit of this design is that it allows the receptacle to have a low profile, only 0.03 in. (0.76 mm) above the PCB.
Quality is Critical The quality and construction of
pins and receptacles can vary consid- erably by manufacturer. For the high- est quality and reliability, press-fit pins and receptacles should be mach - ined to tight tolerances and plated with metals that provide the highest conductivity and corrosion protection. Mill-Max designs and manufactures its press-fit pins and receptacles to a high standard; each one is high-speed turned to precision tolerances as tight
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