A smartwatch settles into its charging dock. Two metal contacts compress slightly, charging begins, and the contacts spring back when the watch is lifted away. The parts making that connection are often pogo pins.
Pogo pins are used in wearable devices, handheld terminals, removable control panels and other products that need a compact connection between parts that meet repeatedly. Their small size is useful, but it can make selection deceptively difficult. A pin that fits the available space may still have too little working travel, apply too much force to its pad or run too hot at the required current.
Shenzhen Yongtan Electronics develops pogo pins and connector assemblies for these applications. The starting point for a suitable design is the way the two halves of the product meet, not the appearance of an individual pin.
How does a pogo pin work?
A pogo pin is a spring loaded electrical contact. In a common design, a movable plunger sits inside a barrel with a spring behind it. When the mating surface presses on the plunger, it moves into the barrel. The spring pushes back, keeping the tip against its mating pad. Once the surfaces separate, the plunger returns toward its free position.
The main parts have different jobs:
| Part | Function | What to check |
|---|---|---|
| Plunger and tip | Move under compression and meet the mating contact | Tip shape, alignment, plating and freedom of movement |
| Barrel | Guide the plunger and provide a mounting or termination surface | Dimensions, internal fit and electrical resistance |
| Spring | Provide force throughout the working travel | Force at the installed height, fatigue and temperature performance |
| Tail or termination | Connect the pin to a PCB, wire or other conductor | Soldering method, positioning and mechanical support |
The electrical path depends on the pin's construction. It is incorrect to assume that all current passes through the spring. In many designs, contact between the plunger and barrel forms an important part of the path; some designs use additional features to control that internal connection. Spring force and electrical resistance must both be evaluated at the height the finished product will actually use.
A pogo pin makes electrical contact through compression. It does not, by itself, align two devices, hold them together or seal the interface. Those jobs belong to the surrounding housing, guides, latch, magnets or gasket.
Common pogo pin types
Pogo pins can be described by how they mount, which direction they contact, or what the application demands. The descriptions overlap: a low profile pin may also be an SMT part, for example.
Surface mount (SMT or SMD). The pin solders to a pad on the PCB surface. This can suit compact board layouts and automated assembly. The part and its packaging must be compatible with the intended placement and reflow process. Pad design, solder joint quality and coplanarity also matter.
Through hole. A tail passes through a plated PCB hole and is soldered as specified for the assembly. The hole can help locate the part, although the finished housing may still need to support forces from repeated mating.
Solder cup or wire termination. The tail accepts a wire connection. Wire size, insulation and strain relief need as much attention as the pin itself; a moving cable should not repeatedly pull on the soldered joint.
Right angle or side contact. These arrangements serve products where the available contact face is beside the PCB. The plunger must still be loaded in the direction intended by its design.
Double ended. Spring contact is provided at both ends for certain board or module arrangements. Both mating heights and their combined tolerances have to be checked.
Mechanically mounted and application specific designs. Threaded bodies, miniature pins, extended travel designs and pins intended for higher current address different packaging needs. A description such as "high current" is only useful when it comes with conditions for its rating.
Tip geometry varies too. A rounded tip can suit repeated contact with a flat pad, while a test probe may use a shape chosen to contact a particular test point. Production connectors and test fixture probes can look similar, but their operating conditions and maintenance requirements may differ.
Pogo pin, pogo pin connector and magnetic connector
A single pogo pin is one contact. A pogo pin connector places several contacts in an insulating body at defined positions and spacing. A magnetic connector adds magnets and a mating structure to help the two halves find and hold their intended position.
Magnetic attraction does not replace contact force. Each pin still needs enough compression to make a reliable electrical connection. Pin count also says little about capability by itself. A four pin interface might carry power and ground with two signal lines, but its functions depend on the actual pin assignment and circuit design. Neither pin count nor the presence of magnets establishes a charging power, data protocol or waterproof rating.
SMT or through hole: which mounting method fits?
Choose between SMT and through hole based on the PCB and assembly process. SMT may be attractive when board space is tight or the connector needs to enter an existing surface mount production flow. Through hole mounting can help with positioning when the PCB layout and available space allow it. Neither method automatically gives a stronger finished interface.
Consider what happens when someone presses a device into its dock at an angle. That force travels through the contact, solder joint, PCB and housing. A locating feature or housing stop can carry much of the mechanical load before it reaches a small solder joint. The same principle applies to a cable that might be pulled sideways. It is easier to solve these loads in the connector layout than after solder joints begin failing in service.
For SMT, check the recommended land pattern, soldering surface, part stability during placement and reflow compatibility. For through hole designs, check the hole and tail dimensions, board thickness, solder access and space beneath the PCB.
The specifications that decide whether a pin will work
Working travel and installed height
Start with the pin's free height and the height available after the product is fully assembled. Their difference is the intended compression. This must remain within the recommended working travel across the full tolerance range of the housing, PCB and mating pad.
At one tolerance extreme, the pin still has to reach the pad with adequate force. At the other, it must not be driven beyond its intended travel. The maximum mechanical stroke is not necessarily the recommended operating position, so using the pin's end stop as a housing stop is a poor starting assumption.
Contact force
A force value only makes sense when its compression position is stated. Too little force may allow an intermittent connection under movement or vibration. Too much increases the load on the pad and makes the product harder to mate.
For a connector with several pins, add the forces at their installed positions. That combined force affects the magnet arrangement, latch or weight needed to hold the halves together. The opposing mating pad and its support must withstand it as well.
Current, resistance and heat
Pin diameter alone cannot establish a current rating. The internal current path, tip-to-pad contact, termination, PCB traces and wires all contribute resistance. Voltage drop follows \(V = IR\), while heat generated in a resistive part of the path follows \(P = I^2R\). A modest increase in resistance becomes more consequential as current rises.
Specify whether the requirement is continuous current or a short peak. Then measure voltage drop and temperature on an assembled sample at the intended working height and ambient temperature. If several pins carry the same supply, do not assume they share current equally; small differences in compression and resistance can change the load on each pin.
Materials and surface finish
The plunger and barrel need a suitable balance of conductivity, strength and manufacturability. The spring needs to retain the specified force over the expected travel and temperature range. Material choices depend on the pin design, particularly on whether the spring carries a significant share of the current.
Gold plating is common at mating contacts because it resists the formation of insulating surface oxides. Its color does not reveal its thickness, underplate or suitability for repeated mating. The pad that meets the pin needs its own finish specification. Where the product faces sweat, humidity or frequent cleaning, assess corrosion and wear on the complete contact pair rather than choosing a finish by appearance.
Alignment and pin assignment
The tip must land within the usable area of its pad, even when the product approaches with the permitted offset or tilt. Show pin positions, pad sizes, polarity and assembly direction clearly on the drawing.
For magnetic interfaces, consider how the two halves align before the contacts touch. Housing keys and electrical protection may be needed to address reversed or misplaced mating. If the interface carries data as well as power, its pin assignment, return path and cable layout must suit the intended signal. Higher speed signals call for assessment at the actual data rate and protocol.
Operating environment
A wearable charger may face skin oils and daily connection cycles. An industrial terminal may face vibration and dust. A personal care product may be wiped frequently. These conditions influence contact placement, cleaning access, material choice and the housing design.
A gasket can help seal an assembled interface, but a pogo pin does not confer a waterproof rating. Any claimed protection level must be checked on the relevant assembly in its specified state.
From drawing to a workable connector
A useful custom request includes the product drawing or 3D model, mating layout, installed height and available space. Add the required current and signals, expected connection cycles, operating environment, preferred PCB or wire termination, and any limits on mating force.
From those inputs, we can develop a pogo pin or magnetic connector arrangement around the customer's drawing, including pin geometry, layout, mounting and mating structure. Samples should be checked for fit and travel before electrical and reliability testing. That sequence can reveal a tolerance or alignment problem early, when it is still practical to adjust the design.
FAQ
Is a thicker pogo pin always suitable for more current?
No. A larger body may provide more room for a conductive path, but the current rating depends on the complete pin, its mating pad, termination and temperature under load.
Which is stronger, an SMT or a through hole pogo pin?
The mounting name alone cannot answer that. PCB design, soldering quality and housing support determine how the finished assembly handles mating force.
Does a gold plated pogo pin last longer?
Gold can help maintain a stable contact surface, but durability also depends on plating specification, pad finish, alignment, force and the number of mating cycles. Test the contact pair under its intended use conditions.
What is the most important dimension to provide for a custom pogo pin?
Provide both the free height and the required height when the product is fully mated, along with the tolerance range. Those values establish the working compression and allow the contact force and available travel to be assessed.
