In the past few years, electronic products have gone through a rapid change. A general trend towards light-weighted and small products, paired with an appealing design, has driven the market. Smaller, thinner, better: This poses challenges to the engineers and product designer as more and more functionality has to be fitted into less and less space. Standard connectors were using a lot of space and were less reliable.
Pogo-Pin connectors became one of the answers to size constraints and customer complaints because of a short life cycle. Due to their unique design, Pogo-Pin connectors are less prone to conductivity losses, use less space and have an extended durability as compared to classical spring connectors.
The pogo pin connector consists of three parts: Plunger, Spring, and Barrel. Pogo-Pins can also be fitted into a housing and can be delivered with a cap to protect them from damage during the assembly process. Form and size are usually customized and can be adjusted based on the client's requirements.
|Back Drill||Bias Tail||Ball|
The drilled tail increases the space for the spring and allows a shorter pogo pin.
The biased tail of the plunger creates a lateral force and improves the contact.
The ball inside stabilizes the contacting areas resulting in a more reliable connection.
Pin Length: ≈ 2.5 mm
Current: 1 A
Pin Length: ≈ 3.5 mm
Current: 2 A
Pin Length: ≈ 4.5 mm
Current: 3~5 A
Beryllium Copper is a good choice for electrical performances but faces regulatory issues in some regions. Nickel Silver is sometimes chosen for very small or thin barrels. For some applications such as high-frequency applications, an unplated phosphor-bronze alloy is the best choice. Barrels generally cannot be heat-treated, as this would interfere with the crimping during the probe assembly process. Selective hardening is an option to improve the hardness of the alloy but can increase the cost of the finished probe.
The basic material choices for the plunger are the same as the barrel materials above, except for the tool steel SK4 which has an advantage on the hardness over the others. SK4 is very hard and can avoid structural damages. It is always heat-treated to lend structural strength and sharp edge integrity to the material. All materials can be easily used by CNC or CAM lathe machines for tooling.
The Spring is usually made with high-carbon steel better known as Music Wire. Music Wire has a very high tensile strength and can tolerate strong forces while having a long mechanical life. Music Wire easily corrodes and stress-relax if exposed to great heat. For this reason, Music wire must be plated to keep its properties also over an extended period of time. An alternative to Music Wire is stainless steel, which is less magnetic and offers a higher temperature rating. Beryllium copper has an excellent fatigue-strength, low resistance, and lower tensile strength. The smaller the Pogo-Pin the smaller is the force value which always results in a trade-off between possible force and Pogo-Pin size.
The Barrel is a deep-drawn tube and usually needs to be plated twice. The first plating is a nickel-plating with a normal thickness of 1 to 2 microns. The second plating is a gold plating which is the final layer with a thickness between 0.1 to 1 microns. A relatively long tube with a small diameter can pose a challenge to the conventional barrel plating techniques. A deep hole must be created at each end of the barrel to allow the plating solution to flow inside the tube and ligate the gold and nickel ions appropriately. The barrel must have an extremely limited scale-length to diameter.
The plunger is usually plated with Gold. Gold is the preferred plating because it provides an excellent conductivity and a high resistance to corrosion. The thickness of the gold plating significantly improves the durability of the product. Depending on the application and financial need, customers can also choose to omit the gold plating or increase its thickness. Alternative plating materials are rhodium, palladium and other noble metals.