『Product Highlight』Kinghelm Screw Terminal KH-A2508-03AB: A Compact and Reliable 2.5mm Pitch Connector

As electronic devices continue to trend toward miniaturization and higher integration, connectors that bridge PCBs with external wiring must provide stable and secure connections within limited space. Screw terminals are widely adopted in industrial control, smart home appliances, power modules, and similar fields because they offer easy wiring, reliable locking, and no need for specialized crimping tools. The Kinghelm KH-A2508-03AB vertical SMT screw terminal is precisely such a product, balancing compact layout with robust performance.

Product Positioning and Basic Structure

The KH-A2508-03AB belongs to the wire-to-board header family of screw terminals. It features a 1x3P pin configuration (single row, three positions), with a total of 3 pins. The pitch between adjacent pins is 2.5 mm, which is considered a compact spacing. Compared to traditional 5.0 mm or 3.81 mm terminals, the 2.5 mm pitch allows more connection points on the same PCB area, helping to meet high‑density routing requirements.

The mounting style is “vertical SMT” (vertical surface mount). After soldering, the terminal body stands perpendicular to the circuit board, with its pins directly attached to the PCB pads for reflow or hand soldering. This vertical SMT approach avoids consuming space on the back side of the board (unlike through‑hole components) and is compatible with automated pick‑and‑place assembly, improving manufacturing efficiency. In terms of dimensions, the height above the board (Z‑axis) is 9.5 mm, and the width at the board edge (Y‑axis) is 8 mm. These two key dimensions provide precise clearance and enclosure design guidance for mechanical engineers, ensuring no interference between the terminal and the product housing.

Electrical Performance: Meeting Standard Low‑Voltage Requirements

Electrical ratings are the primary criterion for judging a terminal’s usability. The Kinghelm KH-A2508-03AB is rated at 3A AC/DC and 250V AC/DC. These ratings cover the vast majority of low‑voltage control signal transmission and low‑power power connection scenarios, such as sensor signal acquisition, PLC I/O expansion modules, LED driver power inputs, and auxiliary windings of small switching power supplies. When selecting this terminal, users simply need to ensure that the maximum continuous current in the circuit does not exceed 3A and the highest working voltage stays within 250V.

Contact resistance and insulation resistance reflect the terminal’s own conduction quality and isolation capability. The KH-A2508-03AB specifies a maximum contact resistance of 20 mΩ – a very low value. Low contact resistance means negligible voltage drop and heat generation at the contact interface between the terminal, the wire, and the PCB pad, thus reducing energy loss and extending product life. For insulation resistance, the product guarantees a minimum of 1000 MΩ (i.e., 1 GΩ). This ensures extremely high isolation between adjacent pins and between pins and the surrounding ground plane, effectively preventing leakage current cross‑talk – especially valuable for analog or low‑voltage signal transmission.

Dielectric strength is an important measure of the safety margin of the insulation system. This terminal withstands 1000V AC applied for one minute without breakdown or flashover. Although the rated working voltage is only 250V, the 1000V withstanding test proves that the insulation material and structural design provide ample safety headroom to handle short‑term overvoltage or surge events.

Material Selection: Balancing Conductivity, Heat Resistance, and Flame Retardancy

Connector materials directly determine solderability, environmental endurance, and service life. For the KH-A2508-03AB, Kinghelm uses brass as the base material for the contacts, followed by a tin plating on the surface. Brass offers good electrical conductivity and adequate mechanical strength, maintaining elastic contact even after repeated insertions or screw locking. The tin plating significantly improves solderability – whether for reflow or hand soldering, it forms a good solder joint quickly – and also provides oxidation and corrosion resistance for long‑term use in typical indoor environments.

The insulating housing is made of PA6T plastic. PA6T is a high‑performance polyamide known for its high heat deflection temperature (typically >260°C) and low moisture absorption. This allows the KH-A2508-03AB to withstand lead‑free reflow soldering peak temperatures (typically 245–260°C) without softening, deformation, or dimensional instability. Compared to ordinary nylons (e.g., PA66), PA6T offers superior dimensional stability at high temperatures.

For flame retardancy, the terminal housing achieves UL94 V‑0 rating. This is a demanding level for plastic materials. The vertical burn test requires that after two 10‑second ignitions, the flame self‑extinguishes within 10 seconds and no flaming drips ignite the underlying cotton. A V‑0 rating means that even in the event of electrical overload or an external fire source, the housing material self‑extinguishes quickly, greatly reducing the risk of fire spread.

Operating Temperature and Usage Boundaries

According to the specifications, the KH-A2508-03AB has a rated operating temperature range of -25°C to +85°C. This range covers the vast majority of commercial and industrial indoor applications, such as ordinary factory floors, distribution cabinets, household appliances, and office equipment. It is worth noting that when the terminal operates for extended periods near the upper temperature limit while carrying the full 3A current, the internal temperature rise may add to the ambient temperature. Therefore, designers should consider derating appropriately based on actual heat dissipation conditions or leave ventilation gaps in high‑density layouts.

Typical Application Scenarios

Based on the parameters above, several typical application directions can be identified:

• Industrial automation equipment: Such as I/O expansion modules for small PLCs, solid‑state relay modules, and stepper motor driver control interfaces. The screw‑type structure firmly locks multi‑strand flexible wires connected in the field and resists moderate vibration.

• Smart home and appliance control boards: Examples include main control boards for air conditioners, display panels for washing machines, and control boxes for smart toilets. The 2.5 mm pitch helps reduce board size, while the vertical SMT form factor suits single‑side layouts.

• LED lighting power supplies: Connections between the input power line and output LED board in constant‑current drivers or dimming modules. The 3A/250V rating is sufficient for most residential and commercial lighting applications.

• Instrumentation: Signal terminals for data acquisition modules, sensor transmitters, and power meters – applications that require convenient wiring and reliable contact.

• Battery management systems: Balance lines or sense lines on some low‑voltage BMS protection boards.
  
  

  Kinghelm KH-A2508-03AB Specification

  
  

Usage Precautions

To fully realize the performance of the KH-A2508-03AB, several practical points deserve attention:

1. Wire selection: For 3A current, copper‑core wires of AWG 24–28 (cross‑section approximately 0.2–0.8 mm²) are recommended. The strip length should generally be 5–7 mm, taking care not to nick the copper strands.

2. Screw tightening torque: Do not apply excessive torque, which could crush the wire or strip the threads. A torque range of 0.2–0.4 N·m is suggested – in practical terms, tighten until snug plus a light extra turn.

3. Soldering process: For hand soldering, keep the soldering iron tip temperature ≤350°C and heating time per joint ≤3 seconds. For reflow soldering, follow the heat resistance rating of PA6T material; peak temperature should not exceed 260°C.

4. Environmental protection: Although the product’s operating temperature goes down to -25°C, pay attention to thermal expansion matching between the housing and solder joints in long‑term low‑temperature or large‑temperature‑swing environments. Avoid direct use in strongly corrosive atmospheres or locations with condensation.
   
   

Conclusion

The Kinghelm KH-A2508-03AB screw terminal offers a compact 1x3P, 2.5mm pitch structure while delivering reliable electrical transmission at 3A/250V. Brass contacts with tin plating ensure low contact resistance and good solderability, while the PA6T housing with UL94 V‑0 flame retardancy provides high heat resistance and fire safety. The vertical SMT mounting style and 9.5mm height above the board give it a clear advantage for space‑constrained PCB layouts. Whether in industrial settings, smart home electronics, or power supply modules, this terminal provides stable and reliable wire‑to‑board connections in tight spaces. If you are looking for a screw terminal that saves board space without compromising reliability, the Kinghelm KH-A2508-03AB is well worth considering.

About Kinghelm

Shenzhen Kinghelm Electronics Co., Ltd.（www.kinghelm.net）has technical backbones from Tsinghua University and UESTC, and has introduced overseas returnee professionals. Kinghelm is able to develop highly reliable and high-performance antenna and connector products.KH series products of "Kinghelm" brand include Beidou/GPS antennas, RF adapter connectors, plug connector, electrical data connectors, terminals, and customized vehicle harnesses, industrial / medical connectors, and special antenna connectors."Kinghelm connects world", Kinghelm has grown with the development of China's Beidou industry. Starting from supplying Beidou/GPS dual mode antennas, IPEX terminals, and RF adapter cables for automotive manufacturers, Kinghelm has continuously developed products. Currently, it has a series of WiFi, Bluetooth, NB-loT, LoRa, Zigbee, UWB, and GSM antennas, RFID tags, RF adapter cables, standard microwave antennas, vehicle grade SMA, SMB, FAKRA holders, coaxial cables, and can customize non-standard antenna connectors based on customer drawings or samples.

KH-A2508-03ABView Product Details