New-Tech Europe Magazine | Dec 2017

Connectors & Cables Special Edition

Selecting The Best Pin Material and Plating Option For My Connector

Danny Boesing, Samtec, Inc.

What are the major costs to build a connector? Which of these are the bigger costs? In other words, what is the most expensive part of a connector? Excluding cable assemblies, the major costs in most board level connectors are the plastic body, the pins, plating on the pins, the labor to assemble it, and the packaging. Often, the bigger ticket items are the pins and the plating. For example, on a micro pitch, high density interconnect product, the pin and plating may account for up to 30% of the total cost of the connector. But on a basic 2.54 mm centerline terminal strip (“header’), it can account for well over 50% of the total cost of the connector. (See Figure 1) The relative size of the plastic body

on a miniature, mold-to-position micro connector is almost always larger than the body on a basic cut- to-position strip-line connector. In other words, there’s more plastic in most micro-pitch interconnects, compared to bigger pitch strip headers. And, of course, the pins are going to cost more if you’re using gold plating. Therefore, selecting the right pin and plating significantly impacts the cost of the connector system. This article is a quick overview of three different base metals commonly used in terminal pins and sockets, and it discusses different plating options available, what most customers use, and why. Disclaimer: The majority of examples in this article relate to Samtec interconnects, but I assume

the cost principles apply to many other interconnect brands as well. Common Base Metals The three most common base metals for most board-to-board connectors are brass, beryllium copper, and phosphor bronze. Brass Brass is the least expensive of the three metals and has excellent electrical properties. Having said that, brass has low yield strength. Because of this, Samtec recommends not using brass in contacts. The concern is the brass beams on the socket will take a permanent set. Meaning, after cycling, the socket beams will spring back to their original position and the terminal

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