0402 PCB Footprint: Dimensions, DFM, and Assembly Guide

0402 is a chip component package used for surface mount assembly, also seen labeled 1005 Metric, R_0402, C_0402. A dependable footprint follows the exact orderable-device drawing rather than the family name: nominal body 1.0 × 0.5 mm nominal, overall span Terminations included in the 1.0 mm body length, seated height Typically 0.35–0.55 mm; component-specific, pitch No lead pitch; two end terminations, pin count 2, and exposed pad None.

Use the exact component drawing or an IPC-7351 density variant; do not scale a 0603 footprint.

Typical uses include dense decoupling, compact pull resistors, wearable electronics. Nominal body size follows the common EIA imperial designation; termination and land dimensions remain part-specific.

• The imperial 0402 code corresponds to metric 1005. Confusing it with metric 0402 creates a footprint roughly four times too small in area.
• Pad length controls both toe fillet and tombstone balance; equal copper and thermal connection on both ends matter more than generous pad area.

For decoupling, place the capacitor beside the power pin and route directly into the plane or local return rather than using the small body merely to save board area.

• Avoid a via touching only one pad unless both ends see comparable copper; unequal heat sinking is a frequent tombstone trigger.

Hand assembly is rated hard. Stencil paste and reflow; microscope-assisted fine-tip work for rework. Watch for tombstoning, part loss on the iron, and excess paste bridging beneath the body.

• Confirm the assembler supports 0402 placement, stencil thickness, and inspection at the selected volume.
• Use reduced or otherwise tuned paste apertures from the assembler instead of assuming a one-to-one paste opening.
• Keep silkscreen out of the tiny courtyard; a body outline is usually less useful than clear reference polarity elsewhere.

Inspection focus:

• AOI needs visible, reasonably symmetric end fillets; a package centered over unequal pads may still pass connectivity while having weak solder volume.
• Inspect tombstones and skew under magnification before electrical test, especially near large copper pours or board edges.

Common mistakes:

• Selecting metric 0402 instead of imperial 0402/metric 1005.
• Using hand-solder-extended pads in a production stencil without checking paste volume.

1. Before approving 0402, compare the exact orderable-device drawing with the library item: body range (1.0 × 0.5 mm nominal), terminal or lead span (Terminations included in the 1.0 mm body length), pitch (No lead pitch; two end terminations), pin count (2), height (Typically 0.35–0.55 mm; component-specific), and exposed-pad definition (None). Record the source drawing revision and every intentional courtyard, toe, heel, side, mask, or paste adjustment.
2. Treat the hard hand-solder rating as a prototype-planning input, not proof of production yield. Review tombstoning, part loss on the iron, and excess paste bridging beneath the body with the assembler, confirm that stencil paste and reflow; microscope-assisted fine-tip work for rework 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. S2Solder-mask web and pad opening. Small pad gaps can leave no manufacturable mask dam at the chosen fab.
2. S2Courtyard and body clearance. Pick-and-place and rework access need more room than the 1.0 × 0.5 mm body suggests.
3. S1Pad count, numbering, and schematic parity. A passive with swapped or missing pad numbers can hide a schematic-to-PCB mismatch.