Daily Brief No.1 · Optoelectronics and Semiconductor Wet Chemicals

Admixor Research now aggregates public-domain information on optoelectronics and semiconductor wet chemicals on a daily basis. This first issue focuses on two fronts: electronic-grade solvents used in wafer and display cleaning (isopropyl alcohol, acetone and acetate esters), and aromatic-free diluents for LED encapsulants. What follows consolidates facts and definitions visible in public sources — it contains no forecasts.

SEMI grades, stated correctly

SEMI has published a unified grading system for wet chemicals since 1975, built on two axes: metallic impurity content and controlled particle size. The familiar designations C1, C7, C8 and C12 are grade codes, not identifiers of any particular chemical — a point that is widely misread. Hydrochloric acid, for instance, carries the standard number SEMI C27-0918 while its grades are again expressed as C7, C8 and C12. The claim that a given solvent "corresponds to SEMI C7" therefore does not hold.

The five tiers, with metallic impurities expressed as mass fraction:

C1 (Grade 1): metallic impurities ≤1000 ppb, controlled particle size ≤1.0 μm, particles ≤25/mL, applicable line width >1.2 μm
C7 (Grade 2): ≤10 ppb, ≤0.5 μm, applicable line width 0.8–1.2 μm
C8 (Grade 3): ≤1 ppb, ≤0.5 μm, particles ≤5/mL, applicable line width 0.2–0.6 μm
C12 (Grade 4): ≤0.1 ppb, ≤0.2 μm, applicable line width 0.09–0.2 μm
Grade 5: ≤0.01 ppb (10 ppt), applicable line width <0.09 μm

The real difficulty is that three naming conventions coexist. Chinese reagent labels use the EL / UP / UPS / UPSS / UPSSS ladder, with single-metal limits of ≤100 ppb, ≤10 ppb, ≤1 ppb, ≤0.1 ppb and ≤0.01 ppb respectively. Vendor disclosures map G5 to UP-SSS, G4 to UP-SS, G3 to UP-S (some vendors use their own SL and UL names instead), G2 to UP and G1 to EL; others state the metallic ion limit directly. When comparing offers across suppliers, do not convert by label name — work backwards from the individual ICP-MS metal limits.

The application decides the grade

Requirements differ sharply by process step, and over-specifying is the most common form of waste:

Semiconductor manufacturing: typically G4–G5, for wafer cleaning, etching and photoresist development
Flat panel display: G3–G4, for glass substrate cleaning, thin-film etching and ITO patterning
Photovoltaics: G1–G2
LED encapsulation: relatively low cleanliness requirement, also in the G1–G2 range

Buying SEMI G5 solvent for an LED encapsulation line does not buy reliability. It buys redundancy nobody will use.

Qualification: which pages of the COA matter

The same sulphuric acid can differ tenfold in unit price between reagent grade and electronic G5 grade. The entire difference sits in ppb-level impurity control, not in nominal purity — so focusing on "99.999% purity" tells you nothing.

The certificate of analysis must list individual ICP-MS results for sodium, potassium, iron, calcium and other key ions. A certificate that states only nominal purity almost certainly does not meet the claimed grade.
Ultrapure water loses resistivity quickly on contact with air; use it soon after opening rather than storing it for repeated sampling.
Packaging matters equally: high-purity polyethylene or fluorinated bottles are required, as glass containers leach sodium.
Ask whether ppb figures are expressed as mass fraction or as ion count — solvents of different density are not directly comparable.

European practice: what REACH actually restricts

The regulatory levers behind the aromatic-free shift sit in Annex XVII of the EU REACH Regulation. Four entries matter most for this product group:

Entry 48 · Toluene: the restriction applies only where the substance or mixture is used in adhesives or spray paints supplied to the general public, at a concentration of 0.1% or more by weight. Industrial and professional uses fall outside this entry — it is the one most often misread as a blanket ban.
Entry 50 · Polycyclic aromatic hydrocarbons (PAH): for plastic or rubber components that come into prolonged or repeated short-term contact with human skin or the oral cavity, any of eight PAHs must not exceed 1 mg/kg; for toys and childcare articles the limit is 0.5 mg/kg. Materials containing carbon black, processing oils or softeners carry the highest risk, and are exactly what aromatic-free formulations replace.
Entry 71 · N-methylpyrrolidone (NMP): listed in Annex XVII in 2018 as reproductive toxicant category 1B; since 9 May 2020 mixtures containing 0.3% or more may not be placed on the market for consumer use, and industrial use must meet DNEL requirements.
Entry 76 · N,N-dimethylformamide (DMF): also reproductive toxicant category 1B, restricted since 12 December 2023, with specific exemptions for polyurethane coatings and synthetic fibre spinning.

A proposal worth scheduling for

On 29 June 2026 the European Commission opened a six-week public consultation on a draft amendment to Annex XVII that would lower the NMP concentration limit in integrated circuit cleaning solvents from the current 8% to 0.1%, with a full ban proposed from 2027.

To be precise: the measure is at the public consultation stage and is not yet an adopted restriction; the final wording and timeline rest with the official EU text. Even so, it is a rare legislative signal aimed squarely at the IC cleaning solvent category. Set against the 2030 target for fully replacing NMP already stated by a leading foundry, it warrants an exposure mapping across three dimensions: which products are affected, which customers depend on them, and which destination markets are served.

Substitution: two routes, run in parallel

Replacing aromatics. Hydrogenation of toluene yields methylcyclohexane (MCH) at purities above 99%, retaining comparable solvency and evaporation rate while removing the toxicity and regulatory profile that come with the aromatic ring. That route transfers directly to LED encapsulant diluent formulation.

Replacing NMP. Candidates include dihydrolevoglucosenone (Cyrene), ethyl lactate, N-butylpyrrolidone (NBP), gamma-valerolactone (GVL), 2-methyltetrahydrofuran and cyclopentyl methyl ether. Fraunhofer IPMS, working on lift-off and photoresist stripping in cleanroom environments, has published a set of criteria that can be used directly as screening thresholds:

Flash point above 60 °C — determines whether the shop floor needs explosion-proof upgrading
Boiling point above 90 °C — determines whether the solvent fits existing cleaning processes
No corrosion of silicon, silicon dioxide, aluminium, alumina or tantalum
Rinsable with isopropyl alcohol or deionised water

China: national standards are a separate dimension

Holding a SEMI grade does not by itself make a product tradable in China. Two mandatory national standards govern market access and must be checked separately:

GB 38508-2020, which limits volatile organic compound content in cleaning agents, applies whenever the product is traded as a cleaning agent. It controls total VOC, the sum of halogenated hydrocarbons such as dichloromethane, formaldehyde, and the sum of benzene, toluene, ethylbenzene and xylene.
GB 30981.1-2025 and GB 30981.2-2025, limits of harmful substances in coatings, were issued on 30 May 2025 and take effect in June 2026. The key changes tighten the VOC limit from ≤670 g/L to ≤420 g/L and bring ancillary materials — putties, hardeners, colour pastes, thinners and sealants — into mandatory scope for the first time, under the same limits and test methods as the base coating.

Bringing thinners into mandatory scope has the most direct effect on LED encapsulant diluents: benzene content, total halogenated hydrocarbons, PAH and formaldehyde in solvent-based ancillary materials all become mandatory test items. Quote to the current version of the standard, not to an older one.

What this means in practice

Build an internal three-column mapping — SEMI grade, metallic impurity limit, vendor label — and compare offers only on individual ICP-MS metal data.
Self-check aromatic content before customers ask. GB 30981.1-2025 has put thinners into mandatory scope, and June 2026 is the dividing line.
Start NMP and DMF substitution programmes early. Even while the proposal is unadopted, switching a qualified system takes years, not months.

What decides whether you stay on the compliant list is not how well you clean up afterwards, but what you prepared eighteen months earlier.

How this issue was assembled

This issue was compiled automatically from public sources: 19 candidate items, all of which passed topical relevance screening, were consolidated into 11 events. Scoring in this batch follows a heuristic method and serves only to order the items.

Eighteen sources carried no publication date. Their recency weight was treated as neutral and no dates were inferred. Standard numbers, limits and dates cited here come from the public sources listed below; before relying on any figure, verify it against the current version of the standard and against the official EU text.

Primary sources for this issue include: Modern Chemical Industry, the IC Materials Industry Technology Innovation Alliance (ICMtia), Chemical Reagents, IPO disclosure filings on the Sci-Tech Innovation Board, Membrane Solutions, ChemSafetyPro, CTI Testing, Sinolook Chem, Fraunhofer IPMS, TotalEnergies, SGS, Zhongke Testing and Global Trade Draft.