2.5 First Article & Golden Board
Verification routines that catch polarity, height, and offset issues before volume—then freeze what “good” looks like so every shift can repeat it.
First Article (FA) is the short, focused trial run that proves a new or revised build is ready for volume. In one controlled pass through printing, placement, and reflow, it confirms that your CAD data, machine programs, feeders, paste, and support setup produce clean solder prints, correct part orientations, and accurate, coplanar placements. During FA, you place a small set of “witness” parts from each package family near board edges so they can be quickly inspected for polarity, X/Y offset, rotation, and height. SPI checks verify paste volume and transfer efficiency on risk apertures, while microscope and AOI reviews catch tombstones, bridges, or float before they hit full production. If you have AXI, you can also spot-check BGA collapse and QFN voiding. When every check passes, you capture a Golden Board—photos of critical features after reflow, plus AOI/AXI screenshots—and a Golden Recipe containing locked printer, placement, oven, and inspection settings. These become the reference for every shift, so first panels match tenth panels, and volume runs start without surprises.
2.5.1 What First Article (FA) really is
FA isn’t a ceremony—it’s a gate your line must pass to prove:
- the data (CAD/centroid, orientations, programs),
- the mechanics (support, clamping, nozzle picks), and
- 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)
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
Bottom line: run a short, scripted FA that proves prints, placements, and reflow on this rev, then freeze the evidence as a Golden Board and Golden Recipe. When every shift loads those, first panels look like tenth panels—and volume starts without surprises.