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2.5 First Article & Golden Board

First Article is the checkpoint where preparation becomes proof. In a controlled trial, it validates that CAD data, machine programs, feeders, materials, and board support all align to produce accurate prints and placements. By placing witness parts, checking offsets, polarity, and coplanarity, then confirming solder performance through AOI or AXI, issues are caught before they spread into volume. The captured Golden Board and Golden Recipe then lock in the “known good” state, providing a repeatable reference for every shift and every lot.

2.5.1 What First Article (FA) really is

FA isn’t a ceremony—it’s a gate your line must pass to prove:

  1. the data (CAD/centroid, orientations, programs),
  2. the mechanics (support, clamping, nozzle picks), and
  3. the consumables (paste, stencil, cleaning cadence)
    produce known-good prints and placements on this rev. When FA is green, you take photos, export settings, and bless a Golden Board and Golden Recipe for the build.



2.5.2 The FA run (one side, one small lot, one tight script)

Scope: 1 panel (or 3 single boards) per side is enough—if you measure the right things.

A) Printer FA (before a single part is placed)

  • Support & gasket: verify support pins/vac tooling under large paste fields; confirm full stencil contact at fiducials and tight areas.
  • First print: one pass → SPI review of the risk features you tagged in 7.4 (fine-pitch, QFN edges/thermal pads, BGA pads).
  • Actions: adjust one knob at a time (angle/pressure/speed, separation, clean cycle), reprint, re-SPI. When TE/height/area are inside limits, freeze printer recipe.

B) Placement FA (place only what you can inspect fast)

  • Witness parts: for each package family (chips, SOT/SOIC, QFN, QFP, BGA/CSP, power pads), place 2–3 parts near a board edge.
  • Checks at the microscope (or height camera):
    • Orientation & polarity: Pin-1/A1, diode/cap polarity, connector keying.
    • X/Y offset: within your machine spec (e.g., ≤±50 µm for fine pitch, ≤±100 µm for chips).
    • Rotation: visually square; log any 90/180 traps and fix the library, not the placement.
    • Z/height & coplanarity: part sits flat; no “see-saw” on QFN corners; BGA ball collapse expected after reflow.
  • Pickup logs: first 20–50 picks per high-runner feeder show near-zero miss/retry; fix peel angle/feeder tension or vision/nozzle now.

C) Reflow spot-check (1st pass through oven)

  • AOI quick-teach with the FA placements; run the board and review:
    • Chips: tombstone/skew ≤ target (ideally zero).
    • QFN/DFN: no float/tilt; edges wetted.
    • QFP/gull-wing: no bridges; heel fillets visible.
    • BGA/CSP: no obvious HIP indicators (dull, non-collapsed balls).
  • AXI sampling (if available): confirm BGA collapse/voiding trend; QFN thermal pad voids inside limit.
  • Test smoke-check (optional now, mandatory before volume): power-safe, programming connector pinned right, boundary-scan chain enumerates.

When all greens are met, complete the rest of the placements and finish the FA lot.



2.5.3 Acceptance matrix (print this on the FA traveler)

Category

What we check

Pass (typical starting limits)

If not, do this

SPI

TE/height/area on risk apertures

Within recipe limits per family (7.6)

Tweak blade/clean/separation; update stencil notes if geometry is the root cause

Orientation/Polarity

Pin-1/A1; diode/cap; connectors

100% correct on witness parts

Fix CAD library + PnP rotation table; re-import centroid if needed

Placement offsets

X/Y, rotation

≤±50 µm (fine); ≤±100 µm (chips); rotations at 0/90/180/270 as expected

Re-teach vision; verify package/nozzle mapping

Heights/flatness

Sit-down/coplanarity

No visible tilt; Z within spec

Add board support; review paste volumes

AOI after reflow

Bridges, tombstones, fillet form

Zero bridges/tombstones on witness set

Adjust stencil apertures or reflow profile; confirm paste health

AXI (spot)

BGA collapse/voids; QFN voids

HIP none; voids ≤ internal/customer limit

Tune profile/atmosphere; consider paste change for voiding

Test hooks

Power on; programming; BSCAN

Enumerates; current within guard; programming connects

Fix connector/keying; complete DFT notes; adjust limits

Accept once everything is inside band and the fix is baked into the recipe/data—not just in someone’s head.



2.5.4 The Golden Board & Golden Recipe (freeze the win)

Golden Board (do not ship):

  • One top-side photo set and one bottom-side, after reflow, covering: overall, tight features, and reference corners.
  • AOI/AXI screenshots for critical parts (e.g., BGA collapse map, QFN thermal).
  • Labels: project/rev/date/line, recipe IDs (printer, PnP, oven), and who signed.

Golden Recipe (rev-locked with the build):

  • Printer: blade angle/pressure/speed, separation/dwell, cleaning interval, bead policy, support map.
  • PnP: program rev, vision versions, rotation table, feeder map (with permanent banks), nozzle map.
  • Oven: profile name and actual time/temperature plot for this board/panel mass.
  • AOI/AXI: library revs; tightened FA thresholds if applied.
  • Test: fixture IDs, boundary-scan device order, smoke-check results.
    Store both with the Golden Data Pack for this rev; stations load by ID, not by memory.



2.5.5 How to keep FA fast (and useful) every time

  • Script it to 15–30 minutes of focused checks; no fishing expeditions.
  • Put witness placements for every package family near board edges in the program—easy to inspect, zero hunting.
  • Use check boxes, not paragraphs on the traveler; require names/time on each row.
  • If a fix changes the outcome (e.g., new squeegee pressure), update the recipe immediately and re-run the affected check—then sign.



2.5.6 Pocket checklists

FA start (printer)

  • Support/gasket good · [ ] First print → SPI green on risk apertures · [ ] Recipe saved

FA placement

  • Witness parts placed per family · [ ] Orientation/polarity correct · [ ] Offsets & heights in band · [ ] Pickup logs clean

FA reflow/AOI/AXI

  • Zero bridges/tombstones (witness set) · [ ] BGA collapse OK · [ ] QFN voids in band

Freeze & publish

  • Golden Board photo set captured (top/bottom, AOI/AXI)
  • Golden Recipe saved (printer/PnP/oven/AOI/test)
  • Traveler signed; MES route released to Volume



By treating FA as a disciplined gate and preserving its results, production avoids false starts and creeping drift. The line launches into volume runs with confidence—stable, consistent, and ready to sustain quality at scale.

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