1.4 Wave Solder Setup

Wave soldering is the original mass soldering process, and its reliability depends on every stage doing its job in sequence. The fluxer and preheater set the conditions, the chip wave scrubs solder into tight gaps, the main wave builds clean fillets, and the peel-off trims the joint without disturbance. When conveyor angle, wave height, and dwell times are tuned to the board’s mass, the flow looks more like a calm river than chaotic whitewater.

1.4.1 What the wave must do (in factory words)

Carry fluxed copper into clean solder,
Wet every barrel and lead,
Leave quietly—no bridges, no icicles, no burns.
Everything you set—fingers/rails, flux & preheat, chip wave → main wave, peel-off/air knives, pallets—either helps that quiet exit or fights it.

1.4.2 The hardware pieces (know your actors)

Conveyor & fingers: titanium/stainless fingers hold the panel (or pallet) at a fixed angle and speed. Finger health = surface quality.
Fluxer: foam or spray (see 13.2). Flux coverage + preheat makes the wave predictable.
Preheaters: IR/hot air zones raise top-side into the right band before solder.
Chip wave (turbulent): scrubs between tight leads, pushes solder upstream into holes.
Main/Lambda wave (laminar): smooth “sheet” that finishes fillets and gives the clean peel.
Peel control: mechanical peel-off bar, air knife, or nitrogen knife breaks the solder film on exit.
Pallets (composite): expose only THT windows; protect SMT and mask splash.

Think: turbulence to enter, laminar to leave.

1.4.3 Starter settings (tune from here)

Parameter	Lead-free (SAC)	SnPb	Notes
Pot temp	260–275 °C	245–255 °C	Go hotter only if design demands—fix prep first
Conveyor angle	6–8°	6–8°	Helps drainage and peel; too flat → bridges
Contact time (total in solder)	2.0–4.0 s	1.5–3.0 s	Thicker/heavier = longer
Chip wave dwell	0.5–1.5 s	0.5–1.0 s	Enough scrub; don’t overcook
Main wave dwell	1.0–2.5 s	1.0–2.0 s	Where fillets are finished
Wave height	1–2 mm rise above board	same	Just kiss the bottom; flooding splashes
Top-side temp at entry	110–140 °C (VOC-free) / 90–120 °C (alcohol)	100–130 °C	See 12.2 for flux-specific bands

Orientation: Put fine-pitch & dense rows leading into the chip wave first (so the scrub does its job) and long rows exit last (so peel is clean).

1.4.4 Fingers, rails & support (bridges start here)

Finger spacing: close enough to keep panels flat; add center support pins for thin or heavy-copper panels.
Cleanliness: brown, sticky fingers → solder won’t wet uniformly under them. Wipe and run finger-cleaner coupons as scheduled.
Edge clearance: leave ≥ 3–4 mm from copper to conveyor finger path; avoid solder wicking along copper right to the finger.
Lubrication: use approved high-temp minimal films if required; over-lube = flux contamination.

1.4.5 Peelers, air knives & the quiet exit

Peel-off bar: small bar (often titanium) just downstream of the main wave that lightly wipes/deflects the solder film as the board exits.
- Set height to just touch the fresh fillet meniscus; too high = gouges, too low = useless.
Air/N₂ knife: narrow jet blowing along the direction of travel right after the main wave.
- Low, even flow trims icicles; too much creates ripples → bridges.
Timing: a brief dwell after the main wave before the knife lets fillets finish; then a short, sharp assist.

Use the smallest intervention that gives a clean peel—don’t sandblast your joints.

1.4.6 Chip vs main wave (how they work together)

Chip wave: high-energy, small crest throws solder upstream into gaps and holes—great for 0.8–2.0 mm pitches, DIP rows, and uneven masses.
Main wave: smooth sheet that levels and drains.

Tuning sequence

Prove flux & preheat (13.2).
Set chip wave height & dwell until bridges between fine pins disappear.
Set main wave height & dwell until exit icicles disappear and fillets look even.
Add peel-off/knife only if small tails persist.

If you try to make the main wave do chip wave’s job, you’ll crank it too high and invite splash/bridges.

1.4.7 Pallet aperture tricks (cheap geometry, big wins)

Dams: leave 2.5–3.0 mm mask/pallet land around openings—seals stop leaks and wave undercut.
Directional windows: taper the entry edge slightly (ramp) so solder meets copper gently; keep exit edge sharp to encourage peel.
Labyrinths: for tight, parallel rows, add a narrow throat at entry and a wider exit—reduces local turbulence but lets solder drain.
Built-in thieves: a tiny downstream island after fine-pitch rows pulls bridges off the last pin.
Step-downs: thinning pallet locally around hungry pins lets them see a bit more wave height without flooding neighbors.
Titanium fences/inserts: drop-in guards near tall SMT as a reversible trial before you cut a new pallet.

1.4.8 Fast symptom → small fix (don’t turn five knobs)

Symptom	First move	If still there…
Bridging in fine rows	Raise chip wave 0.2–0.5 mm or dwell +0.3 s	Increase conveyor angle 1–2°; add thief / pallet throat
Bridging at exit	Add peel-off contact or light air/N₂ knife	Lower main wave 0.2–0.5 mm; shorten main dwell
Icicles/spears	Slightly faster exit + small knife	+5 °C pot; trim dwell; check lead protrusion (12.1)
Poor top-side fill	Verify flux & top-side temp; slow belt (longer contact)	Raise chip wave or pot +5 °C; second pass on stubborn rows
Solder balls/spitting	More preheat dry (not hotter last zone)	Lower chip wave a touch; confirm flux dose uniform
Dull joints/de-wet	+5 °C pot or +0.3 s main dwell	Check finish age/oxidation; consider N₂ over waves
Shadow non-fill (under shields)	Angle board to wave; add micro flux access or second attack	Pallet step-down or partial re-route so wave sees the pins

Always re-check flux UV pattern and top-side temp before you crank pot temperature.

1.4.9 First-article setup (10–15 minutes that saves a day)

Flux proof: UV or weight coupon—coverage even on exposed THT windows.
Preheat profile: TCs near the densest THT; hit your top-side band.
Waves idle: set chip and main to starter heights; verify angle and conveyor speed.
Single pass: run one panel; watch contact lines and peel.
Inspect: bridges, icicles, top-side fill at the worst rows.
Adjust one knob: chip dwell/height → main dwell/height → peel/knife.
Lock recipe with a comment (“chip +0.3 s dwell; main −0.2 mm; knife 10%”).

Take two clear photos (before/after) of the same row—add to the Golden Recipe.

1.4.10 Maintenance & health (waves go bad slowly)

Dross & level: skim on schedule; keep solder level in spec—low level fakes a short wave.
Pumps/impellers: worn pumps pulse → random bridges; listen/feel each start of shift.
Nozzles: nicks change flow; dress or replace.
Heaters & sensors: calibrate; a lying thermocouple drives “mystery” defects.
Flux system: clean spray heads/foam stones; log °Bé / acid number; keep lids closed.
Finger cleaner: run a cleaner coupon; wipe rails; grime = de-wet lines.

1.4.11 Pocket checklists

Setup (per product)

Flux pattern even; dose logged
Top-side temp at entry in band (per flux)
Angle 6–8°; conveyor speed to meet 2–4 s contact
Chip wave height/dwell set; main wave set; waves centered to pallet windows
Peel-off/knife off (start clean), enable only if needed

First article

No bridges after chip tuning; clean peel after main
Top-side fill on test header/critical holes
Photos saved; recipe rev + notes updated

If defects rise mid-run

Re-check flux & preheat before touching pot
Change one of: chip dwell/height, main dwell/height, peel/knife
Record change; verify on next panel

Daily care

Skim dross; verify solder level
Inspect nozzles & pumps; finger path clean
Flux °Bé/acid number within band; spray pattern verified

With disciplined setup and small, targeted adjustments, wave soldering delivers uniform joints without splatter or rework. The process rewards consistency: clean hardware, measured tweaks, and pallets that guide the solder stream make every pass stable and repeatable.