SOT-23-5 PCB Footprint: Dimensions, DFM, and Assembly Guide

SOT-23-5 is a gull wing package used for surface mount assembly, also seen labeled TSOT-23-5, SOT-25, SC-74A variants. A dependable footprint follows the exact orderable-device drawing rather than the family name: nominal body About 2.9 × 1.6 mm nominal, overall span About 2.8–3.0 mm lead span, seated height Typically 0.9–1.45 mm; TSOT can be thinner, pitch 0.95 mm, pin count 5, and exposed pad Normally none.

Match the exact five-lead package drawing; SOT-23-5, TSOT, and SC-70 families are not interchangeable.

Typical uses include LDO regulators, op-amps, load switches. Names such as SOT-23-5 and TSOT-23-5 describe related but not universally identical outlines; use the MPN drawing.

• Three leads sit on one side and two on the other, leaving a missing center lead position that helps identify orientation.
• Many LDOs rely on board copper for heat despite the small body; allowable dissipation falls quickly without the datasheet test land.

Place input and output capacitors at their respective pins with a short shared return that does not carry noisy load current through a feedback node.

• Keep enable and feedback nets away from fast edges and route thermal copper according to the lead that carries the die paddle internally.

Hand assembly is rated moderate. Fluxed drag soldering or stencil reflow. Watch for bridging adjacent pins and using the wrong sot-23-5 pin convention.

• Use a real pin-one mark; the asymmetric lead count is not always obvious in an assembly preview.
• Check toe extension and mask web at 0.95 mm pitch rather than widening every pad for hand soldering.
• Treat thin TSOT height as a separate mechanical variant when clearance under a shield matters.

Inspection focus:

• Inspect all five toe fillets and check for a bridge hidden near the center three-lead side.
• Power up current-limited and verify regulator input, output, and enable states before loading the rail.

Common mistakes:

• Substituting a pin-compatible-looking LDO whose input, ground, and output pins differ.
• Placing both capacitors nearby visually but connecting them through a long shared trace.

1. Before approving SOT-23-5, compare the exact orderable-device drawing with the library item: body range (About 2.9 × 1.6 mm nominal), terminal or lead span (About 2.8–3.0 mm lead span), pitch (0.95 mm), pin count (5), height (Typically 0.9–1.45 mm; TSOT can be thinner), and exposed-pad definition (Normally none). Record the source drawing revision and every intentional courtyard, toe, heel, side, mask, or paste adjustment.
2. Treat the moderate hand-solder rating as a prototype-planning input, not proof of production yield. Review bridging adjacent pins and using the wrong sot-23-5 pin convention with the assembler, confirm that fluxed drag soldering or stencil reflow is compatible with the build, and require the S1 connectivity gate plus relevant S2 geometry checks to pass against the released footprint and selected fabrication profile.

Manufacturing gate checks:

1. S1Pad count, numbering, and schematic parity. Five-pin analog parts frequently differ in enable, ground, feedback, and output mapping.
2. S2Solder-mask web and pad opening. Three adjacent 0.95 mm leads need a consistent mask web and paste print.
3. S2Courtyard and body clearance. Capacitors must be close electrically without overlapping rework access.