A PCB relay is a board-mounted electromechanical relay designed to sit directly on a printed circuit board rather than in a panel-mounted socket or DIN rail holder. It is the standard switching component wherever a low-power control signal — from a microcontroller, logic circuit or automation controller — needs to switch a separate, often higher-power load while keeping the two circuits electrically isolated. The defining characteristics of a PCB relay are a small footprint, a coil voltage compatible with common control electronics, and a dielectric barrier between coil and contact circuits that general purpose or automotive relays are not specifically optimized to provide at this scale.
PCB relays are typically available with coil voltages from 5V to 48V DC, which covers most control electronics used in automation and electronics assemblies. Logic-level coil options sit at the low end of that range and are intended to interface more directly with transistor or driver-IC output stages common in microcontroller-based designs. When specifying coil voltage, confirm not just the voltage figure but the coil current draw against what your driver circuit can actually source — a coil rated for 12V but drawing more current than your driver transistor can switch will not operate reliably even though the voltage matches on paper.
On the output side, PCB relays commonly carry rated currents from 5A to 30A depending on the model, which is enough to switch small motors, solenoids, heating elements or lighting circuits directly from the board. As with any relay, the rated current on the datasheet should be read against the actual load current with margin, and inductive loads such as motors or solenoids may need additional protection components (such as a flyback diode or snubber) depending on the design — a detail that sits outside the relay specification itself but affects relay life in service.
PCB relays are available in through-hole (THT) and surface-mount (SMD) packages, and the choice affects more than board layout. THT relays are inserted through plated holes and typically soldered on a wave or hand-solder line; they tend to offer stronger mechanical retention, which matters in designs subject to vibration or where the relay sees physical handling during assembly or field service. SMD relays are placed and reflow-soldered alongside other surface-mount components, which suits high-volume automated assembly lines where board density and placement speed are priorities. Some product lines offer the same electrical specification in both packages, which lets a design carry over an established contact rating and coil voltage while changing only the assembly process — worth checking during RFQ if your production line is standardized on one soldering process.
Because PCB relays frequently sit between a low-voltage control board and a higher-voltage or higher-current load circuit on the same board, the isolation between coil and contact circuits is a safety-relevant spec, not a secondary detail. Dielectric strength figures are model-specific and should be confirmed against the datasheet for the exact part number, particularly if the end design is itself certified under UL or VDE. Typical certifications referenced for PCB relays include UL, VDE and RoHS, with dielectric strength and creepage/clearance distances confirmed per datasheet rather than assumed from a general product family description.
| Parameter | Typical Range | Selection Note |
|---|---|---|
| Coil voltage | 5V–48V DC | Logic-level options available for microcontroller interfacing |
| Rated current | 5A–30A | Confirm against actual load with margin |
| Mounting | THT / SMD | Match to your assembly process (wave/hand vs. reflow) |
| Isolation | Coil-to-contact dielectric barrier | Dielectric strength confirmed per datasheet |
| Typical certification | UL, VDE, RoHS | Required set depends on end-product certification |
| Typical application | Electronics, automation, instrumentation | Control-signal to load-circuit switching |
Before requesting a quote, gather four things: the coil voltage and driver circuit's available current, the contact current and voltage of the load being switched, the mounting preference (THT or SMD) matched to your assembly line, and any certification requirement tied to your end product's own compliance marks. With those four confirmed, Relayon can match the requirement to a partner factory in its network, attach the documentation for the selected part number, and consolidate PCB relays with any other relay types on the same purchase order into a single shipment — rather than running a separate sourcing process for each relay family.
Send coil voltage, contact rating, mounting type and certification requirement — we match the factory and consolidate with the rest of your order.
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A buyer's comparison of switching speed, lifespan, noise and cost.
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