February, 2019


www.us-tech.com


Advantages of Micro and Nano Pins and Sockets


By Greg Jones and John Buzoianu, Ulti-Mate Connector, Inc.


to reduce the size and weight of their equipment. The use of traditional high-reliability connectors is becoming too large for future designs. Engineers are turning toward micro and nano miniature con- nectors to fulfill design requirements. With this comes a new set of challenges, beginning with the heart of any connector — the contact system. There are four main types of pin and socket


A


contacts used by micro and nano connector manu- facturers. Both MIL-SPEC-style micro and nano connectors use a male pin that is the compliant gender, which engages with a socket contact. Sockets are typically screw-machined, drawn- metal or stamped and formed. While there are advantages to each, the best choice depends on the specific application. For example, a screw-machined or drawn-


metal socket is suitable for crimping stranded or solid wire. Crimped solid round wire is also com- monly used to form through-hole or surface mount terminations. It is these terminations that begin to accentuate the differences between stamped and machined contact.


Stamped and Formed Contacts Stamped and formed contacts are created


from copper alloy that has been selected for its spe- cific conductivity, strength and temper. It then goes through complex progressive stamping dies that form its specific geometry. This process pro- duces a very consistent result which includes an integral contact tail that does not have to be added in a secondary operation, unlike crimping to a solid round wire to create the same surface mount or


s new electronics systems deliver more fea- tures and higher performance, and demand higher reliability, designers are struggling


through-hole contact tail termination. The integral contact tail eliminates any contact resistance as well.


The result is excellent true position and


coplanarity to the bottom surface of the insulator or metal shell, in relation to the plane of the solder pad. This process also enables highly consistent


erations and steps that must be applied during the manufacturing process to ensure reliability and compliance with both specifications, during a mat- ing cycle. For example, a stamped and formed nano socket contact is split from back to front. It is important to realize that as beryllium copper is formed, the molecular structure of the material changes as well, and that this copper alloy itself will not have any memory of its past form. The only way it can be unformed from its new round shape would be to coin the material or use an over- sized gage pin. To further ensure the seam is not expanded,


Integrated flat contact leads compared with standard round leads.


manufacturing repeatability. By comparison, indi- vidual contacts, such as screw-machined or drawn sockets are bulk packaged and handled individual- ly with placement into vibratory bowls leading to a less consistent assembly result. Military specifications M83513 and M32139


require the use of a male compliant pin, which takes on many shapes. The common element is a compliant section of the contact that engages with and compresses inside a mating socket contact. There are obvious advantages to using a stamped and formed socket with a flat tail on the termina- tion end, particularly in surface mount applica- tions.


That being said, there are additional consid-


the back end of the contact is embedded in the plastic molded insulator with a tight tolerance and minimal clearance. This makes it impossible for the seam of the formed socket to unroll and open up. The maximum mating/unmating force allowed by the nano spec MIL-DTL-32139 is 7 oz (198g). In reality, it is typically much less than that. Given Ulti-Mate’s refined manufacturing processes, the tines of the male compliant pin


Even the maximum force allowed by the MIL-SPEC is significantly


less than the strength required to open the seam of a stamped contact, proven by the use of tens of millions of these exact socket contacts in the field.


never touch the seam of the socket barrel and are positioned to consistently make contact with a solid portion of the inner surface of the plated sock- et. Even the maximum force allowed by the MIL-


Continued on page 77


Page 75


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