A spring-loaded pin or a Pogo pin is a specific type of electrical connector used in the case of electronics testing and in many modern electronic applications. Pogo pins are primarily used due to their increased level of durability compared to all other electrical contacts. Pogo pins are also very resilient to vibration and mechanical shock.
The name Pogo has been derived from the resemblance of the pin to that of a Pogo stick. The helical spring present in the pin is responsible for applying a constant normal force to the back of the mating receptacle. This counteracts any undesirable movement that may lead to an intermittent connection. The presence of the helical spring makes the Pogo pin is unique since all other pin mechanisms generally use expansion sleeve or cantilever springs.
A complete connection requires the mating receptacle of the pin to engage. The target of a Pogo pin comprises of a concave or flat metal surface that has no moving parts. The target may be separate components in a part of a complete connector assembly, or it may be a plated area of the board in the case of printed circuit boards.
Structure of a pogo pin
A basic Pogo pin comprises of three main parts
- A plunger
- A barrel
- A spring
When the pen receives Air Force, the spring gets compressed, and the plunger then moves into the barrel. The barrel has been designed in a way that its shape will retain the plungers. This stops the spring from pushing the plunger out if the pin is not logged in place.
In the case of electrical contacts, a certain level of friction is needed to hold the connection in place and maintain the contact finish. However, the friction only needs to be of a certain level. High friction is undesirable as it leads to increased levels of stress and wear on the housings and contact springs. Therefore, a precise normal force of around 1N is needed to generate the friction. In the case of the spring-loaded pin, there must be a slight gap present between the barrel and the plunger so that it can slide easily. If there is a movement or vibration, there may be momentary disconnections. Therefore, the plunger has a small tilt to ensure continuous connection and counteract the vibration.
Materials used for making Pogo pins
- The plunger and the barrel are usually made of brass or copper as base material. A thin layer of nickel is applied on the top.
- Gold plating has been observed to improve contact resistance and durability.
- The springs are made of steel or copper alloys.
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Application of Pogo pins
- Battery terminals on laptops
- Printed circuit board testing
- In-circuit testing
- Board to board connectors
- Integrated circuit testing
- Testing of other electronic devices.
