5.1 Cleaning and Cosmetic Inspection

ShinyFinal hardware and sharp electronics mean little if the final product looks careless. Cleaningcleaning and cosmetic inspection formare the bridge between technical buildfinal quality checkpoints performed just before packaging. This stage ensures the product not only functions correctly but also meets the customer's aesthetic standards (Grade-A surface integrity) and is free of contaminants that could cause long-term reliability issues (e.g., flux residue, fingerprints). This is the last opportunity to address flaws that can result in customer perception, where residues, smears,rejection or liftedfield labelsfailure candue undoto the trust earned by precision assembly. This step is more than presentation: it safeguards optics, protects surfaces, and ensures every unit communicates competence the moment it’s unboxed. Consistent methods, approved materials, and honest inspection lighting turn finishing work into a controlled, repeatable process rather than an afterthought.degradation.

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5.1.1 WhyCleaning thisProtocol stepand mattersContaminant (the one-liner)Removal

CustomersCleaning judgemust withbe theirtargeted eyesto remove manufacturing residues without damaging sensitive components or cosmetic finishes.

A) Target Contaminants and hands. Clean, even, fingerprint-free surfaces reduce returns and make the rest of your build look competent.

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5.1.2 What “clean” means here

Tools

• No loose stuff:Contaminants: Loose particulates (dust, fibers, metal finesfines, fibers - FOD), films (FOD).
• No films: flux haze, adhesive smear, gasketthermal crumbs, TIM/grease mist.
• Nomist), marks:and handling marks (fingerprints, water spots, label squeegee lines.spots).
• NoMandatory damage:Tools: scratches, rubs, lifted paint, light leaks around windows.
• Ready to ship: protective caps on, films removed where required, labels stuck hard.
  

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5.1.3 Tools & consumables (use the right ones)

• Gloves: powder-Powder-free nitrile gloves (no silicone).,
• Wipes: low-lint microfiber or cellulose-poly (class: lens-safe).
• Swabs:wipes, foam-tip,and ESD-safe handlesfoam-tip swabs for tight spots. Air must be filtered and dry.

B) Cleaning Playbook

1. Dry Clean First: Remove loose material using filtered air and a soft ESD-safe brush. Use a tack wipe on seams/vents.
2. Air:Wet Clean (Surface): Dampen a low-lint wipe with filtered, dry blow-off; ionizer on for plastics/lenses.
5. Brush: ESD-safe soft bristle for vents/knurls.
6. Chemicals (plant-approved only):
7. • IPA 70–70%–99% (general degrease; avoid on some polycarbonate/anti-glare)
   • DI waterdegrease) or neutral aqueous cleaner (for salts/smears). Wipe in one direction, flipping the cloth for each pass.
   • Detail: Use swabs for bezel corners, screw heads, and logo relief.
     • Lenses/Windows: aqueousProhibited: Neat IPA on anti-glare coatings. Use the approved lens cleaner (smears/salts)specified by the vendor.
   • AdhesiveSpecials (Residue Removal): Use dry lift first, then minimal adhesive remover (citrus/acetone-free grade) for label bleed—testbleed; first
   • Panel/lens cleaner specified by the display/paint vendor
   • No silicone polishes unless customer spec says so (label fish-eye risk)

Rule: if the finish is unknown, spot test on a hidden area.




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5.1.4 Cleaning playbook (fast, safe sequence)

1. Prep the area: bright diffuse light, clean mat, ionizer on, fresh gloves.
2. Dry clean first: filtered air → soft brush → tack wipe on seams/vents.
3. Wet clean next (smallest effective amount): dampen wipe (don’t flood), wipe in one direction, flip to a clean face each pass.
4. Detail: swabs for bezel corners, screw heads, logo relief, connector shells.
5. Specials:
6. • Lenses/windows: use the approved lens cleaner, not IPA if coating is anti-glare/hard-coat sensitive.
   • Labels: roll with a clean squeegee; if edges lift, re-press with heat per spec or replace—never glue.
   • Adhesive ooze: remove carefully with approved remover; re-wiperinse with IPA/DI to de-scent.water.
   • TIM/threadlocker smearFixes:: liftThreadlocker stain or TIM smudge must be lifted with a dry wipe first, then minimal solvent; keep solvent away from seals.seals and labels.
   • Dry & de-staticFinalize:: finalFinal microfiber wipe; short burst of ionized air burst.
   • Final touch: fit dust caps, port plugs, and protective films only where the customer expects them (don’tfor hideplastics) defects).to dissipate static.
     




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5.1.52 MaterialsCosmetic &Inspection what they like (and hate)Acceptance Cues

Surface	OK cleaners	Avoid	Notes
Powder coat / paint	IPA, aqueous neutral	Strong ketones	Light pressure; circular then straight pass
Anodized AL / bare metal	IPA, mild degreaser	Acidic/alkaline	Watch water spots—DI final wipe
Polycarbonate / acrylic windows	Vendor lens cleaner, DI	Neat IPA/acetone	Use microfiber only; no paper towels
Rubber gaskets/foams	DI wipe	Solvents	Don’t swell; keep cleaners off edges
Labels/PSA	IPA edge wipe	Soaking	After 24 h dwell, edges should not lift
Stainless/EMI fingers	IPA	Oily polishes	Brush along grain; avoid lint caught in fingers




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5.1.6 Cosmetic inspection setupverifies (makethat itthe repeatable)

final assembly meets the aesthetic specification, categorized by surface visibility.

A) Inspection Setup

• Lighting: brightInspection must be performed under bright, diffuse overhead lighting (~1000–1000 – 1500 lx)lx). +Optional optional grazing light can be used to reveal scratches.
• Distance/angle:Distance: Inspection is performed at arm’s length (≈ 500–500 – 600 mm)mm) for Grade-A;A closer only for Grade-B internals.
• Background: matte neutral; cut reflections.surfaces.
• Reference: A golden sample or photo card must be present at the station.




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5.1.7

B) Acceptance cuesCriteria (starterGrade criteria—tuneA toMandates)

your

• Grade-A spec)Faces:

 Mandate: Zero scratches or rubs visible at arm’s length. Color/gloss must be uniform.
2. Windows/Lenses: Must be clear; zero lint under film; no wipes streaks or dust specks.
3. Ports/Shields: Clean, centered; no burr/dust; no fingerprints on shells.

ZoneFeature	Accept	Reject
Grade-A faces (bezels, lids)	No scratches visible at arm’s length; color/gloss uniform	Obvious scratches, rubs, paint chips, swirl haze
Windows/lenses	Clear, no lint under film, no light leaks	Dust specks under lens, edge light leaks, wipes streaks
LabelsLabeling	Aligned to map ±± 0.5–5 – 1.0 mm,; no bubbles,bubbles; edges sealedsealed.	Skew >1°, bubbles,1˚; bubbles; lifted corners,corners smears
Portsnear & shields	Clean, centered, no burr/dust	Metal lip in port, debris, fingerprints on shellsradii.
Seals	Even compression imprint,imprint; no squeeze-out on faceface.	Crushed foam,foam; visible glue/grease on gasket lineline.
Hardware	Heads even,even; witness marks tidy tidy.	Scuffed heads,heads; paint shear,shear; tool tracks around holes.

Light leaks check:Leaks

 dim room, backlight on max—noNo glowing seams at windows/bezel joints.joints (check dim room, backlight max).

Visible


light leak or specks under the lens.

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5.1.83 WhatLabeling, to record (shortRework, and useful)Traceability

Final inspection verifies the permanence of identification and logs any necessary exceptions.

A) Label Application Final Check

• Adhesion:If yourLabels customer/specmust demands:be checked for full adhesion. If the label is new, roll with a clean squeegee for 3 – 5 seconds (per spec). If edges lift, the label must be replaced, not glued.
• Protection: Protective films must be removed only where required; protective caps and port plugs must be fitted for shipping.

B) Traceability and Rework Record

• Data Capture: The final cosmetic release tick (Grade-A/labels/windows)PASS/FAIL) must be recorded by the inspector. Any exceptions (e.g., photoGrade ofB frontblemishes) panel,must andbe any exceptionsnoted with the location.
• ForRework rework: note method/chemicalRecord: If rework is performed (e.g., using adhesive remover), the method/chemical, area, and final PASS check.check Attachmust be logged and attached to the SNSerial Number (SN). record.
  




Final

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5.1.9 Common residues → best removalChecklist

ResidueMandate	SourceCriteria	FixVerification Action
FOD Removal	Fingerprints/oilsInterior enclosure vacuumed; zero metal chips/snippings remain.	Handling	IPAFinal orinspection lensusing cleaner;filtered freshair glovesconfirms no loose material.
Grade A Standard	Dust/fibersNo scratches, gouges, or rubs visible at arm's length.	Packaging,Inspection clothperformed under	bright, diffuse overhead lightingIonized air + microfiber; avoid paper wipes.
Cleaning Integrity	AdhesiveExterior bleedsurfaces wiped with approved solvent; zero adhesive residue.	Labels/foamAudit tapeconfirms	Edgeno with adhesive remover →neat IPA rinse;used replaceon ifanti-glare/sensitive edge won’t sealcoatings.
Label Adhesion	FluxExternal hazelabels verified for full adhesion; alignment ± 1.0 mm.	Clean squeegeeLate solderused touch-ups	IPAto withpress lightlabels; brush;no avoidbubbles floodingor nearlifted sealscorners.
Functional Cleanliness	TIM/pasteFlux smudgeresidue, thermal grease, and fingerprints removed.	HeatInterior sinkvisual install	Drycheck liftconfirms →no minimalprocess solvent; keep off gaskets/labelscontamination.
Cosmetic Final	ThreadlockerProtective staincaps/plugs fitted; labels adhered; no light leaks.	TorqueFinal opsrelease requires inspector sign-off on	Dry wipe quickly; if cured, leave ifGrade-A cosmetic spec allows—don’t smearstatus.




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5.1.10 Common traps → smallest reliable fix

Trap	Symptom	First move
“Polish” with silicone	Later label lift/fish-eye	Ban silicone polish; re-clean with IPA; re-label
Over-wet cleaning	Streaks, seep under bezels	Damp, not dripping; edge-wipe only
IPA on coated lens	Crazing/film damage	Use vendor lens cleaner; replace if damaged
Paper towels	Micro-scratches, lint	Switch to low-lint microfiber
Cleaning before film peel	Trapped dust	Peel late, ionize, then final clean
Ignoring dwell on PSA	Edges lift in pack	Respect 24 h dwell; warm press if spec’d




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5.1.11 Pocket checklists

Before

• Ionizer on; bright diffuse light; clean mat
• Approved wipes/chemicals at hand; fresh nitrile gloves
• Label map & golden photo card visible

Clean

• Dry: filtered air → brush → tack wipe
• Wet: minimal solvent; one-direction strokes; swap faces often
• Lenses with approved cleaner only; labels rolled and sealed

Inspect

• Grade-A faces: no visible scratches at arm’s length
• Windows: no dust/leaks; LEDs clean; light-leak check
• Labels: position ±0.5–1.0 mm, no bubbles, edges sealed
• Hardware & seals tidy; witness marks clean

Closeout

• Caps/plugs fitted; required films applied/removed per spec
• Cosmetic release ticked; photos (if required) bound to SN
• Place on clean rack or straight to pack cell




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A disciplined approach to cleaning and cosmetic inspection keeps defects from slipping through and prevents costly rework or returns. By respecting materials, following a structured playbook, and inspecting with rigor, products leave the line polished, protected, and ready to represent the brand at its best.