Ultra-Thin SMT Tact Button 4.3x4.3 For Portable Devices

Overview

• Ultra-thin, low-profile SMT tactile switch optimized for compact, battery-powered products such as wearables, earbuds/charging cases, trackers, smart remotes, handheld instruments, and other portable devices.
• Crisp, consistent tactile feedback with short travel for power, reset, pairing, mode select, and user interface inputs.
• Top-actuated design with robust metal cover; side-actuated variant available on request.

Key Features

• Compact footprint: 4.3 × 4.3 mm with ultra-low height options (0.80 / 1.00 / 1.20 mm).
• Momentary SPST-NO contact (normally open) with stainless tactile dome.
• Multiple operating forces to match end-user feel (light to firm).
• Long mechanical life up to 1,000,000 cycles (force dependent).
• Pb-free reflow compatible; tape-and-reel for automated SMT assembly.
• RoHS and REACH compliant; halogen-free materials.
• Optional enhanced sealing for improved dust/splash resistance.

Typical Applications

• Power and reset buttons in wearables, trackers, IoT sensors.
• Pairing/mode buttons in earbuds/charging cases and BLE remotes.
• User input keys on slim handheld devices and modules.
• Hidden/flush service buttons in compact enclosures.

Electrical Specifications

• Contact rating (max): 12 VDC, 50 mA.
• Low-level switching capability: down to 1 V, 10 µA.
• Initial contact resistance: ≤100 mΩ (≤200 mΩ after life test).
• Insulation resistance: ≥100 MΩ at 100 VDC.
• Dielectric withstand: 100 VAC for 1 minute.
• Contact bounce: ≤5 ms (typ. 1–3 ms).

Mechanical Specifications

• Function: Momentary, tactile (SPST-NO).
• Operating force options: 120 gf (light), 180 gf (standard), 250 gf (firm); 300 gf on request.
• Total travel: 0.15 ± 0.05 mm (pre-travel typ. 0.10 mm).
• Return force: ≥20 gf.
• Mechanical life (typical):
  • Up to 1,000,000 cycles @ 120 gf
  • Up to 500,000 cycles @ 180 gf
  • Up to 200,000 cycles @ 250 gf
• Terminals: 4 SMT pads (two pairs electrically common).
• Actuation: Top-press; side-actuated variant available.

Materials

• Cover/shield: Stainless steel (SUS).
• Tactile dome: Stainless steel.
• Base: High-temperature LCP or PA9T.
• Terminals/contacts: Copper alloy with nickel underplate; gold (G) or silver (S) plating options.
• Plunger/actuator: High-temperature PPS or LCP.

Environmental and Reliability

• Operating temperature: −40 to +85°C.
• Storage temperature: −55 to +105°C.
• Humidity: 40°C, 90–95% RH, 96 h (no electrical/mechanical damage).
• Thermal shock: −40/+85°C, 100 cycles.
• Vibration: 10–55 Hz, 1.5 mm amplitude, 2 h per axis.
• Mechanical shock: 100 g, 6 ms, 3 axes.
• ESD robustness (typical): 8 kV air, 4 kV contact (system-level performance depends on PCB and enclosure).
• Optional sealing: Consult for IP67-style sealed variant.

Dimensions and Footprint

• Body size: 4.3 × 4.3 mm (L × W).
• Height options above PCB: 0.80 / 1.00 / 1.20 mm nominal.
• Actuation area (center boss): approx. 2.0–2.4 mm diameter.
• Coplanarity: ≤0.10 mm.

Recommended land pattern (top-actuated, 4-pad)

• Corner terminal pads: approx. 1.0 × 0.8 mm each.
• Pad pitch (X and Y): ~3.1 mm between opposing pad centers.
• Solder mask: Non-solder mask defined pads recommended; provide a central keep-out (no copper/no solder mask) of 1.8–2.2 mm diameter beneath the dome to prevent flux entrapment and ensure reliable click.
• Courtyard/assembly keep-out: ≥0.25 mm around body for pick-and-place clearance.

Soldering and Assembly

• Reflow (Pb-free) profile: Peak 250–255°C; 20–40 s above 217°C; preheat 150–200°C for 60–120 s; ramp ≤3°C/s; max 2 reflow cycles.
• Hand rework: Short, localized heating; avoid prolonged exposure. Do not press the actuator while solder is molten or before cool-down.
• Wave soldering: Not recommended.
• Cleaning: Avoid immersion and aggressive solvents; use controlled spray/brush methods. Protect the actuator opening from direct solvent jets.
• Moisture sensitivity: MSL 1 (typical for non-sealed); verify per lot for sealed variants.
• Handling: Use a compliant pick nozzle centered on the metal cover; avoid off-axis loading.

Packaging

• Tape-and-reel: 8 mm embossed carrier tape, 4,000–5,000 pcs/reel (availability per height option).
• Orientation mark on tape for consistent placement; EIA-481 compliant leader/trailer.

Compliance and Safety

• RoHS and REACH compliant; halogen-free.
• UL not typically required for low-voltage signal switches; certification support available on request.

Design Guidelines for Portable Devices

• Place near enclosure interface but away from microphones/cameras if acoustic click is a concern; foam isolators can reduce noise.
• Add ground stitching vias around the switch perimeter if the button is user-accessible to improve ESD discharge to chassis/ground.
• Consider a nearby low-capacitance TVS diode for user-accessible lines.
• Debounce in hardware or firmware (typ. 5–10 ms).
• For button caps or actuator posts, ensure vertical load and allow 0.2–0.3 mm mechanical tolerance; avoid shear loads.
• Maintain enclosure clearance above the actuator; prevent continuous pre-load from gasket or case.
• Avoid conformal coating intrusion under the metal cover; mask the switch area or use coating-compatible variants.

Notes and Cautions

• Do not actuate the switch during pick-and-place or reflow.
• Do not exceed the rated over-travel or apply forces >3 N; avoid prying or side loads.
• Control flux volume; keep central area free of solder/flux to protect the dome.
• Verify tactile feel and enclosure stack-up in the final assembly; tolerance stack can change force/travel.

Availability

• Samples, 3D models (STEP), and recommended footprint files available on request.
• Custom actuator height, force, plating, and packaging options supported for volume programs.