Why this is a high-vacuum fabricated chamber, not a painted steel tank

• High-Purity Stainless (SUS304/316L) Outgasses Orders Of Magnitude Below Carbon Steel.​ A carbon-steel vessel rusts, traps oil, and releases H₂O/HC at 10⁻⁴ Pa floor; 316L low-sulfur stainless with controlled ferrite has a specific outgassing rate near 1×10⁻¹⁰ Pa·m/s after bake-out, letting the chamber settle at 10⁻⁷ Pa . Runwo’s announcement page states the chamber “adopts high-purity stainless steel materials to ensure internal cleanliness” and must hold 10⁻³–10⁻⁷ Pa — that is not a decorative sentence: material purity is the first outgassing gate. For a semiconductor transfer chamber, the wall metal is part of the process atmosphere.
• Electron-Beam Welding Gives A Seamless Root; TIG Leaves A Penetration Dip That Outgasses.​ TIG welding a 6 mm 316L seam penetrates 3–4 mm from each side, leaving a 1–2 mm unwelded root that traps oxide and pumps forever. Electron-beam welding (EBW) in vacuum melts the full joint in one pass, no filler, no oxidation, seam width 1–2 mm, post-weld delta-ferrite controlled . Runwo’s technical note “utilizing advanced electron beam welding technology to achieve seamless sealing” is the root-integrity statement—same logic as the submerged-arc root on the prior Base Beam article, lifted from 200 h vibration fatigue to 10⁻⁷ Pa outgassing. A TIG chamber can be He-tight at 10⁻⁶ but never settles at 10⁻⁷ because the root keeps talking.
• Mirror Polishing (Ra ≤0.4 μm) Cuts Particle Shedding Versus Shot-Blast Finish.​ A shot-blast inner wall (Sa2.5) has micro-pits that trap abrasive grit and shed particles onto the wafer path; mirror polishing (mechanical + electropolish option) closes the pits, drops particle count, and lowers surface area for adsorption . Runwo specifies “achieving mirror-level smoothness on the inner walls through precision polishing processes”—the 0.4 μm Ra number is the cleanroom gate, not a shine preference. A transfer chamber with Ra 1.6 μm fails Class 100 particulate audit; Ra 0.4 passes.
• ISO/CF Flange-Face Flatness (≤0.05 mm) Is The Leak Driver, Not Wall Thickness.​ A 10 mm wall with a warped CF flange leaks; a 6 mm wall with a CNC-machined flange flat to 0.05 mm and a 1.5 mm knife-edge holds 10⁻⁷ Pa on a copper gasket. Runwo CNC-machines flange faces on a gantry center after stress-relief, so the knife-edge seats evenly and the He-leak rate lands <1×10⁻⁹ Pa·m³/s on a helium mass spectrometer . “CNC Machined Flange ISO CF Connection” in the long-tail is the tolerance-chain statement, exactly like the undercarriage-interface point on the Base Beam piece.
• Runwo/Cdwl Vertical Integration Closes The Semiconductor-Chamber PO.​ Changzhou Runwo Environmental Protection Technology (czrunwo.com, Cdwl brand, ISO 9001, 10,000–30,000 m² plant, gantry machining + automated welding + NDT in-house) moved from metallurgical equipment into semiconductor vacuum hardware in 2026 . For a semi OEM the path is: send chamber dwg → Runwo nests 316L plate/forging → EBW seam → stress relieve → mirror polish inner → CNC flange + CF ports → He-leak test + cleanroom wipe → ship. One PO covers chamber + flange adapter + viewport collar + pump port stub. Same closure logic as the Base Beam article, translated from paving-frame fabrication to high-vacuum semiconductor fabrication.

Runwo / czrunwo.com supply context

• Maker:​ Runwo Environmental Protection Technology Co., Ltd. (Changzhou Runwo), brand code Cdwl
• Site:​ czrunwo.com
• Product:​ Vacuum Chamber (semiconductor / vacuum equipment)
• Material:​ High-purity SUS304 or SUS316L stainless steel, low sulfur, ferrite-controlled
• Weld:​ Electron-beam welding (seamless root), optional TIG cosmetic pass
• Inner finish:​ Mirror polish Ra ≤0.4 μm, electropolish optional
• Flange:​ ISO-K / CF (ConFlat) standard, CNC machined face, flatness ≤0.05 mm, knife-edge per ASTM F139
• Rating:​ 10⁻³ Pa to 10⁻⁷ Pa operating, He-leak <1×10⁻⁹ Pa·m³/s (helium mass spectrometer)
• Options:​ Viewport collar, pump port stub, RF/electrical feedthrough flange, water-jacket shell, load-lock door
• Process chain:​ Plate/forging → CNC pre-machine → EBW → stress relief → mirror polish → final CNC flange → He-leak + cleanroom wipe → pack
• Cert:​ ISO 9001, material mill cert, He-leak report, dimensional inspection
• URL:​ https://www.czrunwo.com/product/vacuum-chamber/

Key characteristics and application scope

• Product Name:​ Vacuum Chamber
• Alternate Terms:​ Runwo Cdwl semiconductor vacuum chamber high purity 316L EB welded mirror polish 10⁻⁷ Pa, ISO CF flange vacuum vessel for transfer reaction load lock chamber czrunwo, Changzhou Runwo Environmental Protection vacuum equipment chamber fabrication
• Chamber class:​ High-vacuum fabricated stainless chamber (not carbon-steel tank, not acrylic bell jar, not cast-aluminum vessel)
• Core Applications:
  • Semiconductor transfer / load-lock chamber​ — 10⁻⁷ Pa, CF flanges, robot port, viewport, He-leak certified
  • Vacuum coating / PVD chamber​ — mirror inner wall, pump port stub, RF feedthrough flange
  • Photovoltaic pilot-line process vessel​ — 316L, bake-out capable, cleanroom wiped
  • Equipment OEM sub-supply​ — Runwo fabricates to OEM dwg, machines flanges, ships He-leak tested
  • Non-use cases:​ atmospheric-pressure housing (no flange flatness needed), food-grade tank (different polish spec), cast iron vacuum pump body (different material/outgassing class)
• Companion logic:​ Same Runwo PO pairs vacuum chamber + single crystal furnace base & shell + base beam for a full semiconductor-equipment structural crate.

Application logic by buyer type

• Semiconductor OEM (East China, etch tool):​ Runwo Cdwl transfer chamber, 316L, 800 mm dia, EB welded, Ra 0.4 inner, CF250 + CF160 ports, He-leak <1e-9, cleanroom Class 1000 wipe, 6-week lead, 4-pc batch.
• PV Pilot Line (EU):​ Mirror-polished 304 chamber for ALD demo, ISO-K flanges, bake-out to 150 ℃, Runwo supplies flange adapters to existing pump set.
• Vacuum Coating Shop (SE Asia):​ Replace TIG-welded 304 chamber that stalls at 10⁻⁵ Pa with Runwo EBW 316L, reaches 10⁻⁷, coating defect rate drops.
• Equipment Refurbisher (US):​ Buy Runwo bare chamber, fit own CF flanges/feedthroughs, half the cost of brand-name replacement.

Procurement and spec checklist

Conclusion: The chamber is only as clean as its worst seam