# Electroless nickel bath formulations

Supplied electroless nickel components, disclosed ingredients, coating families, measurement bases, and limits of manufacturer claims.

Reviewed: 2026-10-30

Tags: chemicals, electroless-nickel, formulations, reference

## Identity and boundaries

Caswell’s SDSs list **45% nickel(II) sulfate in Part A**, **25% sodium hypophosphite in Part B**, and **30% sodium hypophosphite in Part C**. The **5–10% NH₃** in the Part B entry is the strength of the ammonium hydroxide ingredient solution. The SDS lists that ingredient at 1% of Part B. [Part A SDS][a] [Part B SDS][b] [Part C SDS][c] Electroless deposition uses chemical reduction without an external plating current. [ASTM B733-22(2026), public scope][astm]

Caswell describes A and B as make-up components and A and C for replenishment. The supplied components, circulating bath and deposited alloy have separate compositions. [Caswell tutorial, make-up and replenishment sections][tutorial]

Electroless nickel-boron, Ni-B, is another coating family. Uyemura identifies BEL-801 as boron electroless nickel for metallized ceramic substrates. Its palladium activators are separate products that initiate plating. Electrolytic nickel is also a separate chemistry category on the same page. A nickel-containing product name alone does not identify an electroless formulation. [Uyemura US product page][uyemura]

## Disclosed supplied components

The following examples are the Caswell Inc US SDS identities ELECA, ELECB, and ELECC. Each served document is version 1.1, issued 27 January 2020. These are ingredient disclosures for separate supplied liquids, not a combined bath formula. The concentration fields print "%" without explicitly identifying mass or volume basis. [Part A, sections 1 and 3][a], [Part B, sections 1 and 3][b], [Part C, sections 1 and 3][c]

| Supplied identity | Section 3 ingredient entries | Disclosure limit |
| --- | --- | --- |
| Electroless Nickel Plating Solution Part A, ELECA | Nickel(II) sulfate, CAS 7786-81-4, 45%; water or other non-reportable ingredients, CAS 7732-18-5, 55% | The nickel-salt percentage is not an elemental-nickel assay. [SDS, page 2][a] |
| Electroless Nickel Part B, ELECB | Sodium hypophosphite, CAS 7681-53-0, 25–25%; ammonium hydroxide solution identified as 5–10% NH₃, CAS 1336-21-6, 1–1%; other non-reportable ingredients, 74–74% | The ammonia strength belongs to the named ingredient solution. It is not the ammonia percentage of Part B. [SDS, page 2][b] |
| Electroless Nickel Part C, ELECC | Sodium hypophosphite, CAS 7681-53-0, 30–30%; sodium hydroxide liquid, CAS 1310-73-2, 2–2%; other non-reportable ingredients, 68–68% | "Liquid" does not specify the strength of that sodium-hydroxide ingredient. [SDS, page 2][c] |

B and C explicitly omit specific names and formulas as trade secrets. Their section 1 aliases also mention electroless cobalt and nickel/cobalt. Those aliases do not disclose a cobalt concentration or establish a deposited alloy composition. The B footer says version 1.1 supersedes 1.2, an unresolved revision inconsistency. [B SDS][b], [C SDS][c]

Synthesis: an SDS table that totals 100% can still contain undisclosed formulation constituents. Non-reportable material is not necessarily water alone. Absence from these tables does not establish absence of a complexant, buffer, stabilizer, contaminant, or other additive. The disclosures do not establish interchangeability between B and C.

## Ingredient functions and composition bases

MacDermid Acumen's patent EP 3 030 688 B1 describes constituent functions in its electroless-nickel technology. It is primary evidence for the distinctions below, not evidence that Caswell, Atotech, or Uyemura uses the patented formulation. [Patent, paragraphs 0017–0026][patent]

| Constituent role | Supported distinction |
| --- | --- |
| Nickel source | Soluble nickel salts supply nickel ions. Salt identity includes its counterion and, where applicable, hydration state. |
| Reducing agent | The reducing agent is oxidized as nickel ions become nickel metal. The patent associates hypophosphite with Ni-P and soluble boranes with Ni-B. |
| Complexant | Complex formation helps keep nickel soluble and retards precipitation of insoluble nickel compounds. |
| Buffer | Buffers resist changes in acidity. Some compounds can have both buffering and complexing functions. |
| Stabilizer | Stabilizers influence bath lifetime and alloy content. A stabilizer is not synonymous with the nickel source or reducing agent. |

Source: [patent description, paragraphs 0017–0026][patent]. The patent identifies bismuth-based stabilizers in its own invention. It does not establish a universal stabilizer chemistry or the composition of a named commercial product.

Synthesis: weight percent, wt%, means mass per hundred units of total mass. A supplied ingredient wt%, an elemental-nickel equivalent, a working-bath concentration in g/L, and a deposited-alloy phosphorus or boron percentage have different denominators. A hydrated nickel salt includes crystal water in its formula mass. A salt percentage cannot become elemental-nickel content without a defined salt/hydrate basis and percentage basis. The inspected Caswell sheets do not supply enough information for that conversion. Their sodium-hypophosphite entries are not deposit-phosphorus measurements.

## Supplied-liquid properties and missing conditions

These section 9 entries belong to the named Caswell supplied products. They are not working-bath control values. [A, page 4][a], [B, pages 3–4][b], [C, page 4][c]

| Product | Appearance and odor | Reported pH | Reported relative density |
| --- | --- | --- | --- |
| ELECA | Green liquid; odor field blank | 3.5 | 1.34 |
| ELECB | Clear liquid; strong ammonia odor | 5.5 | 1.18 |
| ELECC | Clear liquid; odorless | 5.4–5.8 | 1.195 |

The sheets do not specify pH sample preparation, measurement temperature, or method. They do not identify the relative-density reference temperature or reference material. Relative density is a ratio, distinct from density expressed in g/mL. None of the three section 9 tables gives a measured solids or active-content value. A blank property field means unreported, not zero. [A][a], [B][b], [C][c]

Synthesis: these incomplete measurement conditions prevent a rigorous comparison with a value measured on a diluted sample or at another temperature. Solubility in water does not establish solids content, active content, or an approved dilution. Appearance and odor do not identify the undisclosed ingredients.

## Named coating families and property context

The Atotech examples are English-language global product flyers, not regional component SDSs. The flyers report deposited phosphorus percentages without explicitly stating mass versus atomic percentage. Their low-, mid-, and high-phosphorus labels apply to the named products. [LP 1124][lp], [MP 400][mp], [HP 1151][hp]

| Named process and edition | Manufacturer's deposit claim | Property context and limits |
| --- | --- | --- |
| Nichem LP 1124, ©04/26 | Low phosphorus, 2–4% P | As-plated hardness 650–750 HV; heat-treated hardness 800–1000 HV. Test force, dwell, specimen preparation, and treatment details are absent. [Two-page flyer][lp] |
| Nichem MP 400, ©08/22 | Mid phosphorus, 7–9% P | As-plated hardness 550–650 HV₀.₁. The flyer retains a load designation but supplies no complete hardness method or dwell. Its 300–600 GU gloss claim lacks a stated measurement angle. [Two-page flyer][mp] |
| Nichem HP 1151, ©08/22 | High phosphorus, 10–12% P | Manufacturer describes the deposit as nonmagnetic and pit-free at high thicknesses. The flyer gives no magnetic test protocol or numerical thickness for that claim, and no hardness value. [Two-page flyer][hp] |
| Uyemura BEL-801, undated US page | Boron electroless nickel; nickel purity over 99% | Approximately 800 Hv as plated. The page does not state a test force, dwell, exact boron percentage, or purity measurement basis. [Product description][uyemura] |

Synthesis: HV identifies Vickers hardness. A bare HV range and a load-designated HV₀.₁ range are not a matched test comparison. As-plated and heat-treated values describe different coating states. The BEL-801 nickel-purity claim does not by itself yield a boron percentage because the balance and analytical basis are unspecified.

Atotech's LP flyer compares its product with an unnamed conventional low-P process. That comparison does not establish every competing formulation's properties. MP 400's gloss graph lacks a complete test protocol. Its medical-device flange photograph is an application illustration, not medical approval. [LP flyer, page 2][lp], [MP flyer, page 2][mp]

## Free-of claims and standards scope

Atotech describes LP 1124 as free from ammonia, lead, cadmium, EDTA, and boric acid. Its MP 400 and HP 1151 flyers state lead- and cadmium-free chemistry. All three make ELV, RoHS, and WEEE claims. These are manufacturer statements for the identified products and document editions. They provide no lot-specific detection limits, analytical results, or complete jurisdiction-specific conformity evidence. [LP][lp], [MP][mp], [HP][hp]

Atotech separately describes ELeVEN products as free of toxic heavy-metal stabilizers. That narrower wording concerns the stabilizer system. It does not mean that a nickel-plating chemistry contains no metals. [Atotech portfolio][portfolio]

ASTM B733-22(2026)'s public scope concerns autocatalytic nickel-phosphorus coatings on metallic products for engineering uses. It distinguishes deposited-alloy properties from plating-solution chemistry and identifies subsequent heat treatment as influential. It is a coating specification, not a supplier concentrate identity or a Ni-B specification. Only the public scope is used here. No paid acceptance criteria are reproduced. [ASTM public scope][astm]

Synthesis: a product's free-of label, coating family, or cited standard does not establish current-lot compliance or customer acceptance. Corrosion, wear, solderability, magnetic behavior, and adhesion claims require their own substrate, coating-state, exposure, and test context. These sources establish no universal food-contact, medical, or aerospace approval.

## Source versions and coverage limits

Reviewed 30 October 2026 PDT. Caswell's complete US SDSs are publicly served 2020 editions, not certificates of analysis. The undated tutorial describes its multipart system. No revision history establishes continued regional equivalence or equivalence to newer single-component products. The three Atotech flyers are product literature dated April 2026 or August 2022. They do not disclose the supplied make-up and replenisher part compositions. Uyemura's US page is undated and directs technical-data requests separately.

The MacDermid patent was published as B1 on 30 October 2019. Its description supports ingredient-role terminology, not a reconstruction of a current proprietary formula. The evidence leaves undisclosed components, present regional grades, current-lot assays, and fully conditioned performance tests unresolved. This reference contains no bath formula, component ratios, or operating recipe and establishes no customer's process capability.

Related references cover [Surface-finishing processes](../../processes/finishing/index.md), [nickel sulfate](../substances/nickel-sulfate.md), and [sodium hypophosphite](../substances/sodium-hypophosphite.md). The latter two remain separate substance subjects, not complete formulated products.

[a]: https://caswellplating.com/content/sds/Electroless%20Nickel%20A.pdf
[b]: https://caswellplating.com/content/sds/Electroless%20Nickel%20B.pdf
[c]: https://caswellplating.com/content/sds/Electroless%20Nickel%20C.pdf
[tutorial]: https://caswellplating.com/electroless_tutorial.html
[patent]: https://data.epo.org/publication-server/rest/v1.2/patents/EP3030688NWB1/document.pdf
[lp]: https://www.atotech.com/wp-content/uploads/2026/04/Flyer26_03_EN_Nichem_LP_1124_low_res.pdf
[mp]: https://www.atotech.com/wp-content/uploads/2022/10/Flyer_EN_Nichem_MP_400_2022.pdf
[hp]: https://www.atotech.com/wp-content/uploads/2022/10/Flyer_EN_Nichem_HP_1151_2022.pdf
[uyemura]: https://www.uyemura.com/images/pcb-finishes/electroless-nickel.html
[portfolio]: https://www.atotech.com/products/general-metal-finishing/wear-resistance/electroless-nickel-coatings/
[astm]: https://store.astm.org/b0733-22r26.html