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Overview

General comment

This dataset represents a modern controlled high-purity SF6 producer of the kind operating in Germany and Japan. The geography label GLO is a technology scenario rather than a geographic production average: electricity is taken from the global medium-voltage market. Two alternative supply situations are documented for a user who is not buying from such a producer. Both change the plant-gate emissions rather than the material or energy inputs. A high-purity plant with no abatement vents about 0.5% of its output as SF6, and about 0.06% of it as the carbon tetrafluoride impurity it removes. An uncontrolled supply chain vents about 2.2%, with the same 0.06% of carbon tetrafluoride. The central case shipped here is 0.1% and 0.002% of output respectively. Cylinder-heel venting - the residual gas left in returned cylinders, about 8% of contents on the intergovernmental default, 12-15% where nothing is recovered and 1-2% under a closed-loop return scheme - belongs to the use and distribution phase and is deliberately not in this production dataset. A user reconciling against a reporting rule that books producer-side container venting to production must add it back as a separate use-phase flow.

Technology
Direct fluorination of molten sulfur (S + 3 F2 -> SF6) followed by deep N5.0 cryogenic purification, at a modern controlled producer (emission-free filling, plasma-burner abatement)
Geography
Global

System boundary

System boundary - Sulfur hexafluoride (SF6)System boundary figure: identity, gate in, entering flows, the dashed system boundary and the unit processes inside it, the reference product, emissions and waste, and below it the flows that are recorded but not quantified. No inventory quantities.Sulfur hexafluoride (SF6)DECLARED BOUNDARYGate-to-gate SF6 synthesis + purification(caustic scrub, S2F10 thermal destruction,drying, cryogenic rectification,compression/liquefaction).ENTERING FLOWSElectricityWaterMaterialsSYSTEM BOUNDARYAGGREGATED PRODUCTION MODELModelled as one production operation.This dataset models the production of this material as a single aggregated operation at the supplier plant.Its inputs and outputs are recorded against that operation rather than a step-by-step recipe.REFERENCE PRODUCTSulfur hexafluorideNot stated in the dataset recordEMISSIONS AND WASTEEmissions to airEmissions to waterWaste routesRECORDED BUT NOT QUANTIFIEDIn scope, left out of the quantified inventoryCut off below the significance threshold, or with no background dataset available - each is listed with its reason1FLOWsystem boundaryreference flowentering flowemission / waste

The figure groups this dataset's unit processes by class. It is not a count of manufacturing steps; each process runs over as many passes as the flow requires, and those pass counts ship with the dataset.

Download this figure (SVG)

Data quality and references

Composite DQI 2.5 Good
Reliability
4.0
Completeness
3.0
Temporal
1.0
Geographic
2.0
Technological
4.0

Pedigree scores follow the ecoinvent data-quality matrix: 1 is the best attainable, 5 the weakest. The composite is their aggregate.

Sampling procedure
No plant measurements were available for this product, so nothing here is a sampled primary value. The synthesis route, its stoichiometry and its operating conditions come from producer synthesis and purification patents, gas-supplier product datasheets and the NIST thermochemical tables. The electricity is a mechanistic unit-operation estimate built from those conditions, because no measured energy per kilogram of SF6 synthesis is published. The plant-gate fugitive rate comes from a producer's own published emission-reduction disclosure, cross-checked against intergovernmental greenhouse-gas inventory guidance and an atmospheric top-down study. Documents published between 1978 and 2025.
Coverage status
Complete
Pedigree-scored source files
Not stated
Dataset sources
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
  • Stoichiometric calculation

Technosphere inputs

12 flows. Quantities are not published; they ship with the dataset on Circa.

Elemental fluorine Materialkg · -4.8% / +19%
Derivation basis
  • Quantity from the formulation/production-route recipe; upstream life cycle provenance is carried by the linked upstream unit process (see the technosphere reference)

The sources for this row are listed below.

Source citations (dataset-level)
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
Upstream REEL dataset
Fluorine (F2)
Background dataset
Modelled by REEL; see the upstream dataset above.
Notes
F2 from HF electrolysis - see linked fluorine dataset (count-once)
Uncertainty
-4.8% / +19% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kg
Sulfur Materialkg · -5% / +35.7%
Derivation basis
  • Stoichiometric calculation; ProBas SF6 (hochrein)

The sources for this row are listed below.

Source citations (dataset-level)
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
Background data
ecoinvent 3.12
Background dataset
sulfur
Notes
Elemental sulfur (Claus/petroleum-recovered); net fresh input (unreacted S recycled)
Uncertainty
-5% / +35.7% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kg
Nitrogen (diluent / purge) Materialkg · -60% / +300%
Derivation basis
  • The model specifies this input from the production route, either from the chemistry of the reaction or from the allowance the route sets for it. It also states the excess the route uses and the share it recovers for reuse.

The sources for this row are listed below.

Source citations (dataset-level)
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
Background data
ecoinvent 3.12
Background dataset
nitrogen, liquid
Notes
ESTIMATE (Tier low). Inert diluent to moderate the exothermic fluorination + inerting/purge; NOT incorporated - vented and tracked as an inert N2 emission to air (see emissions to air, closes the N2 balance). Patents confirm dilution but give no kg/kg figure. GWP 0.
Uncertainty
-60% / +300% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kg
Sodium hydroxide (caustic scrubbing makeup) Materialkg · -50% / +400%
Source citations
  • US5639435A (caustic scrub); US4174375 (lime regeneration); engineering estimate
Background data
ecoinvent 3.12
Background dataset
sodium hydroxide, without water, in 50% solution state
Notes
KOH used equivalently; NaOH modelled. Makeup only (caustic regenerated by lime).
Uncertainty
-50% / +400% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kg
Quicklime (lime for fluoride precipitation) Materialkg · -33.3% / +55.6%
Derivation basis
  • Stoichiometric (2 F- + Ca(OH)2 -> CaF2 + 2 OH-); US EPA fluoride precipitation

The sources for this row are listed below.

Source citations (dataset-level)
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
Background data
ecoinvent 3.12
Background dataset
quicklime, milled, loose
Notes
On-site lime precipitation of fluoride wastewater; CaO slaked to Ca(OH)2
Uncertainty
-33.3% / +55.6% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kg
Activated alumina / molecular sieve (adsorbent) Materialkg · -80% / +300%
Derivation basis
  • The model specifies this input from the production route, either from the chemistry of the reaction or from the allowance the route sets for it. It also states the excess the route uses and the share it recovers for reuse.

The sources for this row are listed below.

Source citations (dataset-level)
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
Background data
proxy-mapped
Background dataset
aluminium oxide, metallurgical
Notes
Thermal-swing-adsorption drying bed, multi-year life amortized to per-kg basis. Negligible mass; included for completeness. ESTIMATE (Tier low).
Uncertainty
-80% / +300% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kg
Electricity, reactor island, Global (GLO) ElectricitykWh · -50% / +125%
Derivation basis
  • Energy demand specified by the model.

No source is attached to this row.

Source citations
Not stated
Background data
ecoinvent 3.12
Background dataset
electricity, medium voltage
Notes
Remove the reaction exotherm (the refrigerated fraction, at the chiller's coefficient of performance), blowers, molten-sulfur feed.
Uncertainty
-50% / +125% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kWh
Electricity, scrubbing and drying, Global (GLO) ElectricitykWh · -60% / +140%
Derivation basis
  • Energy demand specified by the model.

No source is attached to this row.

Source citations
Not stated
Background data
ecoinvent 3.12
Background dataset
electricity, medium voltage
Notes
Scrubber recirc; ~400 C S2F10 destruction (electric heater); molecular-sieve regeneration. If the S2F10 pyrolysis is gas-fired rather than electric, this term falls by roughly a quarter; the patents do not say which is used.
Uncertainty
-60% / +140% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kWh
Electricity, cryogenic rectification, Global (GLO) ElectricitykWh · -73.7% / +136.8%
Derivation basis
  • Energy demand specified by the model.

No source is attached to this row.

Source citations
Not stated
Background data
ecoinvent 3.12
Background dataset
electricity, medium voltage
Notes
Low-temp distillation/refrigeration to strip CF4/N2/O2 to N5.0. DOMINANT and most-uncertain term (argon-column analogue + refrig duty / COP). Central nudged above the 1.5 mechanistic point since bottom-up sums undercount integration/part-load; upper band covers a dedicated column (~3.5). This is the largest electricity uncertainty.
Uncertainty
-73.7% / +136.8% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kWh
Electricity, compression and filling, Global (GLO) ElectricitykWh · -75% / +100%
Derivation basis
  • Energy demand specified by the model.

No source is attached to this row.

Source citations
Not stated
Background data
ecoinvent 3.12
Background dataset
electricity, medium voltage
Notes
Compress to ~2.1 MPa (20 C) liquefaction + condensation + filling. Small: SF6 has a low ratio of specific heats and the liquefaction pressure is modest, so the isentropic compression work is a small fraction of this row.
Uncertainty
-75% / +100% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kWh
Electricity, facility overhead, Global (GLO) ElectricitykWh · ±100%
Derivation basis
  • Energy demand specified by the model.

No source is attached to this row.

Source citations
Not stated
Background data
ecoinvent 3.12
Background dataset
electricity, medium voltage
Notes
Plant nonprocess energy allocated to SF6. ~10% uplift on direct process electricity, per DOE 2018 MECS Chemicals (NAICS 325) nonprocess share ~9.5% of onsite energy. NOT a cleanroom/ fab multiplier - this is a chemical plant. Rigorous public chemical gate-to-gate LCI often omits this entirely; included as a small, documented, defensible line (min 0 = omit).
Uncertainty
±100% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kWh
Fresh water WaterL · -41.2% / +76.5%
Derivation basis
  • Water demand specified by the model.

No source is attached to this row.

Source citations
Not stated
Background data
ecoinvent 3.12
Background dataset
tap water
Uncertainty
-41.2% / +76.5% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
L

Outputs and waste

Fluoride precipitation sludge (CaF2 + excess lime) Solid wasteg · -36% / +52%
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Background data
ecoinvent 3.12 treatment route
Background dataset
Landfill or fluorospar recovery
Notes
~118 g CaF2 + ~7 g excess lime. Non-hazardous per project W1.3 convention (CaF2 is fluorspar-equivalent; >90% recoverable to steel-industry flux in TW/KR) - conservatively landfilled (no ecoinvent recovery activity). CAVEAT: real sludge may carry trace sulfur-fluorides; a conditional/leach-test classification could apply per site.
Uncertainty
-36% / +52% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
g
Spent adsorbent (molecular sieve / activated alumina) Solid wasteg · -80% / +300%
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Background data
ecoinvent 3.12 treatment route
Background dataset
treatment of hazardous waste, underground deposit
Notes
Fluoride-contaminated inorganic TSA drying bed, amortized over multi-year life
Uncertainty
-80% / +300% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
g
Purification residue (heavy sulfur-fluorides / spent scrubber solids) Solid wasteg · -80% / +200%
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Background data
ecoinvent 3.12 treatment route
Background dataset
treatment of hazardous waste, underground deposit
Notes
Rectification heavy-ends + spent scrubber solids, DISTINCT from the aqueous CaF2 sludge. Composition ~0.5 g S + ~0.5 g F (trace sulfur-fluorides) + ~4 g inert (Ca/O/moisture) - both the S and F are COUNTED in the mass balances (an output, not internal recycle). Sulfur fluorides are INORGANIC (hazardous inorganic); controlled disposal (underground deposit).
Uncertainty
-80% / +200% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
g
Spent lithium getter (pyrophoric) Solid wasteg · -75% / +400%
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Background data
ecoinvent 3.12 treatment route
Background dataset
treatment of hazardous waste, underground deposit
Notes
Grade-specific N5.0 Li-getter (US5298229A); pyrophoric -> controlled disposal. Negligible mass; included for grade-specific completeness.
Uncertainty
-75% / +400% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
g

Emissions to air

8 elementary flows released to air by this dataset's own operations. Quantities are not published; they ship with the dataset on Circa.

Sulfur hexafluoride Emission to airg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Air (non-urban air or from high stacks)
Formula
SF6
CAS number
2551-62-4
ecoinvent 3.12 elementary flow
Sulfur hexafluoride
Notes
PLANT-GATE PRODUCTION FUGITIVE = 0.1% of output (1 g/kg) - MODERN CONTROLLED high-purity plant (this dataset's central). The DOMINANT GWP contributor of the route; only the mass flow is given, because this is an inventory dataset. Anchored on Solvay Bad Wimpfen's disclosed plant-gate rate (0.51% 2004 -> 0.06% 2010 -> ~0.02% 2013, after emission- free filling + >99.9%-DRE plasma burner), triangulated by the IPCC 0.5% base factor (AFEAS 2004) and Simmonds et Al. 2020 (0.5% developed-country). Band 0.05-0.5% (0.5-5 g/kg). CO-EQUAL SCENARIOS, set out in the general comment: no-abatement high-purity ~0.5%, the top of that band and this row's published maximum; uncontrolled supply ~2.2%. EXCLUDED (use/distribution phase, NOT double-counted here): cylinder-HEEL venting - the IPCC 8% "high-purity" default is PREDOMINANTLY heel venting per IPCC 2006 GL Vol.3 3.10.2.2 (Suizu 1999), a customer/returned-cylinder loss, NOT a plant emission. German 2025 top-down study (PMC12706706) hints real Bad Wimpfen fugitives may exceed disclosure, so the 0.5% band ceiling is retained.
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Carbon tetrafluoride Emission to airg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Air (non-urban air or from high stacks)
Formula
CF4
CAS number
75-73-0
ecoinvent 3.12 elementary flow
Tetrafluoromethane
Notes
GRADE-SPECIFIC to N5.0 and the 2nd GHG lever. Parameters kept SEPARATE: crude_CF4 ~0.1 vol% (~0.6 g/kg removed; single-source US4380532A, LOW confidence; high case 0.5 vol% ~3 g/kg = band max); routing = to plant destructor; DRE = 0.97 (repo PLASMA value, consistent with Solvay's >4000 C SF6 plasma burner which destroys CF4 well; the 0.87 THERMAL value is a fab point-of-use TRANSFER PROXY, not a producer measurement). CF4 (sublimes -128 C) will not condense with SF6, so N5.0 (<0.5 ppmw) requires cryogenic removal that dielectric grade (<75 ppmv) can skip. Carbon source = feed/ electrode carbon IMPURITY (not a tracked input; ~0.08 g C/kg ends up in CF4). CENTRAL residual = 0.6 x (1-0.97) ~ 0.02 g/kg vent. CO-EQUAL no-abatement SCENARIO: CF4 VENTED 0.6 g/kg at 0.1 vol%, up to 3 g/kg at 0.5 vol% (band max). Destroyed CF4 (CF4 + 2 H2O -> CO2 + 4 HF): ~0.58 g -> ~0.29 g CO2 (see CO2 emission below) + ~0.47 g HF (folded into HF emission). Fate is the single largest grade-specific GHG uncertainty (undisclosed).
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Carbon dioxide Emission to airg
Derivation basis
  • Stoichiometry (CF4 destruction); JAWMA 2024 (abatement)

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Air (non-urban air or from high stacks)
Formula
CO2
CAS number
124-38-9
ecoinvent 3.12 elementary flow
Carbon dioxide, fossil
Notes
From destruction of the CF4-air purge + lower fluorides (CF4 + 2 H2O -> CO2 + 4 HF) plus abatement fuel; closes the trace carbon balance (CF4 carbon = feed impurity). Negligible; included for completeness.
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Hydrogen fluoride Emission to airg
Source citations
  • Fugitive estimate (NF3/WF6 analog); US5639435A
Compartment
Air (non-urban air or from high stacks)
Formula
HF
CAS number
7664-39-3
ecoinvent 3.12 elementary flow
Hydrogen fluoride
Notes
Fugitive from handling/scrubber slip; most captured by caustic scrub. GWP~0 but drives AP.
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Sulfur dioxide Emission to airg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.
  • No corresponding ecoinvent dataset or flow was identified for this entry, so it is published with its own quantity and no background link

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Air (non-urban air or from high stacks)
Formula
SO2
CAS number
7446-09-5
ecoinvent 3.12 elementary flow
Not stated
Notes
From trace S-impurity oxidation / SOF2-SO2F2 hydrolysis - NOT a stoichiometric product of the dry elemental route (only forms with moisture/O2 ingress). Negligible as a greenhouse gas, but acidifying.
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Sulfur tetrafluoride Emission to airg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.
  • No corresponding ecoinvent dataset or flow was identified for this entry, so it is published with its own quantity and no background link

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Air (non-urban air or from high stacks)
Formula
SF4
CAS number
7783-60-0
ecoinvent 3.12 elementary flow
Not stated
Notes
Residual lower fluoride after caustic scrubbing (SF4 hydrolyzes readily; mostly captured).
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Disulfur decafluoride Emission to airg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.
  • No corresponding ecoinvent dataset or flow was identified for this entry, so it is published with its own quantity and no background link

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Air (non-urban air or from high stacks)
Formula
S2F10
CAS number
5714-22-7
ecoinvent 3.12 elementary flow
Not stated
Notes
HIGHLY TOXIC lower fluoride; >99% destroyed by ~400 C thermal decomposition + caustic. Trace fugitive only. US5639435A.
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Nitrogen Emission to airg
Derivation basis
  • Mass balance (N2 input = N2 vented)
  • No corresponding ecoinvent dataset or flow was identified for this entry, so it is published with its own quantity and no background link

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Air (non-urban air or from high stacks)
Formula
N2
ecoinvent 3.12 elementary flow
Not stated
Notes
Inert diluent/purge N2, vented (closes the N2 balance; not incorporated in product). GWP 0, benign - included for mass-balance completeness (inert N2 is a valid inventory row).
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g

Emissions to water

3 elementary flows released to water by this dataset's own operations. Quantities are not published; they ship with the dataset on Circa.

Fluoride ion Emission to waterg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Water (surface water)
Formula
F-
CAS number
16984-48-8
ecoinvent 3.12 elementary flow
Fluoride
Notes
POST-treatment RESIDUAL after on-site lime precipitation (CaF2 solubility ~8-15 Mg/L F; ~20 Mg/L in 5 L incl. polishing). Nearly all scrubbed excess-F (~58 g F) leaves as CaF2 sludge, NOT to water (direct-discharge model; no off-site treatment double-count).
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Sulfate Emission to waterg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Water (surface water)
Formula
SO4(2-)
CAS number
14808-79-8
ecoinvent 3.12 elementary flow
Sulfate
Notes
From minor SO2/SF4 neutralization (dry elemental route makes little SOx)
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g
Sodium ion Emission to waterg
Derivation basis
  • The model estimates this flow from the mass balance of the operation and from the share of material the operation loses.

The sources below are this dataset's own bibliography. They are not tied to this row.

Source citations (dataset-level)
Inherited from this dataset's own bibliography, not tied to this row:
  • German UBA ProBas 'SF6 (hochrein)' unit process + LCI result (GEMIS-derived, public)
  • US5639435A - Method for producing SF6
  • US4108967A - Process for preparing SF6 (Solvay-lineage)
  • US6389845B1 / WO2001024913A1 - Separation of SF6 from CF4/air (RECOVERY analogue)
  • AGC Chemicals SF6 product datasheet
  • NIST Chemistry WebBook - SF6
  • IPCC Good Practice Guidance - SF6 industrial processes
  • Billen et al. 2020, Energies 13:1807 (CC-BY)
  • DOE 2018 MECS Chemicals energy/carbon footprint (NAICS 325)
  • Solvay, SF6 Emission Reduction at the Point of Production (2014, EPA-hosted)
  • IPCC 2006 GL Vol.3 Ch.3 Chemical Industry (3.10.2.2, SF6 production)
  • Simmonds et al. 2020, Atmos. Chem. Phys. 20, 7271
  • US4380532A - Fine purification of SF6
  • US5298229A - Purification of SF6 (Li-getter)
  • Performance Evaluation of Commercial-Scale SF6 Thermal Destruction, JAWMA 2024
Compartment
Water (surface water)
Formula
Na+
CAS number
17341-25-2
ecoinvent 3.12 elementary flow
Sodium I
Notes
From the 0.01 kg NaOH scrub makeup (Na leaves as Na2SO4/NaF in effluent); closes the Na balance. Benign (not a regulated pollutant of concern).
Uncertainty
A minimum-maximum range is defined for this flow. Bounds ship with the dataset on Circa.
Unit
g

Flows not quantified

1 flow is recorded for this dataset but carries no quantity: cut off below the significance threshold, or with no background dataset available. It remains inside the declared system boundary; each is listed with its reason.

Not quantified - no background dataset available (1)

Lithium getter (macroreticulate polymer, N5.0 final polish) Materialkg · -75% / +400%
Source citations
  • US5298229A (Li-getter purification of SF6)
Background data
no background dataset
Background dataset
Not applicable: this flow is not quantified in the inventory.
Notes
GRADE-SPECIFIC N5.0 getter (US5298229A) removing O2/H2O to <1 ppm; the bed lasts years and is amortized over its life. Specialty getter - genuinely NOT in ecoinvent (documented gap; negligible mass/GWP). Spent getter is PYROPHORIC hazardous waste, carried as a waste output below. ESTIMATE (Tier low).
Reason
A lithium-based getter polymer for the final oxygen and moisture polish. No dataset in the mapped background answers to it, so the row ships with its quantity disclosed and no upstream link, and the production of the getter stays outside the modelled boundary.
Uncertainty
-75% / +400% around the published quantity. The bounds themselves ship with the dataset on Circa.
Unit
kg

The flows above are this dataset's own records. What follows are the scope rules set once for the whole database in the methodology report, repeated here so every dataset page carries them.

Boundary declared by this dataset

Gate-to-gate SF6 synthesis + purification (caustic scrub, S2F10 thermal destruction, drying, cryogenic rectification, compression/liquefaction). F2 production burden via linked fluorine dataset; sulfur from ecoinvent. Facility overhead (HVAC/lighting/utilities) included as a small explicit electricity line (~10%, DOE MECS chemical-sector nonprocess share), NOT a cleanroom-style multiplier.

Database-wide boundary policy (applies to every REEL dataset)

These boundaries are set once for the whole database, in Chapter 2 of the methodology report, and apply to this dataset wherever they are relevant to it. The excluded flows listed above are specific to this dataset.

Use phase
Product operation is outside the cradle-to-gate scope.
End-of-life treatment
Recycling and disposal are outside the cradle-to-gate scope.
Distribution and retail
The gate is a finished component ready for integration into a higher-level assembly.
Inbound transport of raw materials
Transport of purchased raw materials to the manufacturing facility is already inside the upstream "market for" datasets that users link to a background database, so it is not modelled a second time here. This does not cover freight between REEL production stages, which is modelled where a dataset authors it.
Returnable shipping containers
Where freight between production stages is modelled, the mass moved is the product itself. The shipping container (FOSB, SEMI M31) is returnable capital equipment whose per-trip share is unsourced, so its tare is excluded from the transport effort.
Photomask fabrication
A mask set's embodied burden is amortised across a high-volume production run and is not attributed per wafer. Users assessing low-volume production should add mask fabrication separately; the methodology report gives the basis for the exclusion.
Employee transport, administration and R&D overhead
Employee transportation, facility administration and R&D/pilot-production overhead are outside scope.
Capital goods
Manufacturing equipment, cleanroom construction and facility infrastructure are excluded, on the grounds of absent public data on equipment embodied energy, uncertainty in equipment lifetime and allocation, common practice in electronics LCA, and a focus on the operational inventory. Future versions may include capital goods when sufficient public data becomes available.
Precious metal recovery credits
Scrap recovery credits for precious metals are excluded pending data availability.
Wafer reclaim
Test wafers and scrap are outside the system boundary.

Inside the boundary, linked rather than modelled

Silicon ingot growth and wafer slicing
Inside the cradle-to-gate scope, but treated as upstream material inputs linked to background databases rather than modelled as REEL processes.
Freight between production stages
Where a dataset's product moves between REEL production stages - wafer fabrication to the packaging site, for example - that leg is authored as a transport service and linked to an ecoinvent freight activity. It is measured as a transport effort in tonne-kilometres, not as a mass. Route distances are authored per route class with a stated band; a lower bound of zero is a modelling statement that the two sites can be co-located, not a missing value.

Cut-off criteria

A flow is excluded from a process inventory when it contributes less than 1 % of the total mass of inputs to that unit process, or less than 1 % of its total energy input. The denominator is total process inputs, not product mass. That distinction matters in semiconductor manufacturing, where the input mass of water, chemicals and gases greatly exceeds the product mass, so the threshold removes only genuinely minor flows.

Included regardless of the cut-off

  • Perfluorocarbons (CF4, C2F6, SF6, NF3) - high GWP, EPA regulated
  • Heavy metals (Pb, Cd, Hg, Cr(VI)) - RoHS regulated, high toxicity
  • Volatile organics (photoresist solvents, PGMEA) - air quality
  • Precious metals (Au, Ag, Pd, Pt) - high embodied impacts
  • Ozone-depleting substances (legacy CFCs, HCFCs) - Montreal Protocol