High density, Low profile connectors benefit from new breed of spring-loaded pin

April 27, 2017 // By Jeff Elliott
Connector manufacturers are turning to more affordable H-Pins over traditional pogo-style options without sacrificing performance. For decades, connector manufacturers have relied on traditional spring-loaded, or pogo-style pins, to provide highly compliant, reliable interconnections.

Although expensive, these highly compliant pins are used to connect batteries to docking stations, antennas to PCBs, for rugged, high-shock and vibration applications, or to compensate for floating heights and uneven mating surfaces.

However, with the market drive to continually pack more electronics into ever-thinner, shrinking packages, spring-loaded connectors are playing a new role: as space-saving device to reduce the real estate occupied by the connector itself. Even when miniaturized, connectors with traditional male pins and female receptacles take up valuable space.  This is opening the door for compression-style board-to-board and board-to-device connectors that utilize spring-loaded pins mounted against pads or gold-plated lands on the PCB.  This approach can be used to create mezzanine-tiered board modules as well.

Trouble is, with hundreds of millions of spring-loaded pins required to produce these connectors, the high cost of traditional pogo-style pins remains a considerable barrier. As a result, connector manufacturers are turning to a new breed of miniaturized spring-loaded pins as small as 0.2mm that reduces costs by 30-50%.  These new pins deliver high performance in a highly compliant contact that – unlike pogo-style pins – are manufactured in a fully automated, high-speed production process.

 

Pogo-style pins

For decades the spring-loaded probe, also known as the pogo-style pin, has delivered excellent mechanical and electrical performance.  However, this often came at a high cost. Although designed and manufactured in subtly different ways, the pogo-style pin is typically constructed of 4-5 components that includes a drawn barrel, a wound spring, two screw machined plungers, and some means to bias the plunger to the barrel. Depending on volume, the traditional pogo pin is either assembled completely by hand or with semiautomatic process steps with pins hand-shuttled from process to process. 

As a result, the market stopped using pogo pins for all applications other than the most critical applications that could afford the premium costs. 

Instead, many connector manufacturers turned to alternatives such as bend, buckle, or cantilever-style contacts that require additional space between pins during compression. However, this approach is not viable for fine pitch applications – defined as the number of pins in a small area or the distance between pin centers – required for today’s high density electronics.

Spring-loaded pins, on the other hand, operate in a purely vertical or horizontal fashion, so the maximum space occupied at any time is defined by its diameter. This allows for placement of spring-loaded pins in fine pitch distances as low as 0.2mm.