Guest Blog Post
David Pheteplace, Senior VP, Bishop & Associates
One of the older, widely used contacts, the pogo pin, has long established itself as a reliable and trustworthy technology for many applications. Named after the pogo stick toy over forty years ago, this golden spring-loaded contact has played a vital role in making temporary connections, usually for electronic testing, since it was first created.
More recently, the pogo pin has been used in more “permanent” connections in cell phones, laptops, computers and other electronic devices. Many have come to rely on pogo pins for their durability, relatively small size and their ability to absorb relative large vertical mismatches between the connectors in which they are embedded. In a world where we want to make quick connections with batteries, laptop screens and I/O ports, they have provided a very flexible solution.
As mobile devices began using the USB 3.1 Type C and USB SS, however, the pogo pin design is increasingly challenged. These contacts, although they may be coaxed to operate at these higher speeds, are not intended to operate at higher speeds. For designs that need physical flexibility in high speed applications, it is time to say goodbye to the pogo pin in favor of the Kiss Connector!
What the Pogo Pin was Never Intended to Do
To begin with, the pogo pin was never designed with high-speed data transfer (meaning 5.0 Gbps or higher) in mind. Let’s examine how the pogo pin works. First, the mating end of the contact is usually plated with gold and is often a sharp point. When this sharp point is pressed against the usually softer “mating contact” (typically a gold plated pad), the connection is made.
Since there is no wiping action, as with a standard pin and socket contact, this design is more subject to contamination and corrosion increasing the contact resistance through the connection which makes it more difficult for low voltage, high speed signals to be transmitted.
A second source of design issues is the internal spring. The spring must make good contact with the pogo pin’s plunger and base which can be problematic. The spring also brings inductance into the contact due to its spiral design. Lastly, to overcome issues for using these contacts in matched-impedance systems, each signal circuit must be surrounded by several ground circuits to isolate the contact’s signal path from surrounding signal paths.
For lower frequencies and power transmission, the pogo pin does a great job. When it comes to high speeds circuits, however, the pogo pin shows its inherent design weaknesses.
There are several limiting variables at play that can easily affect a pogo pin’s capacity to function at high speeds. The quality of the materials and the design of the pogo pin are vital to its performance. Poor quality metal, shoddy structural integrity, and cheap construction can cause high levels of contact resistance. Pogo pins rely upon near-perfect contact between the springs and the pin to perform optimally. At higher speeds, the layout of the signal and grounding pins also becomes a critical issue to maintaining the necessary electrical characteristics of the circuit (and requires a significant amount of space).
Is it possible to use pogo pin technology to transmit USB SuperSpeed?…or DisplayPort? Probably not impossible; just not recommended. There’s the issue of cost. High-speed transmission requires high-quality pins, and those run about US$1 each (versus standard contacts at a couple of pennies per mated pair). But more importantly, there’s the issue of reliability and connector real estate usage. You might make it work, but why bother?
It’s time to think about modernizing the technology that enables high-speed connectivity. Fast, sleek, and inherently built for high speeds, the solid-state Kiss Connector removes metal from the connector, eliminates RFI/EMI problems, minimizes alignment issues, drastically reduces the larger footprint required for traditional connectors (and the hole in the side of your device) and operates seamlessly with USB 3.1 Type C and USB SS.
Time to say goodbye to mechanical connectors.