| HS Code | 806853 |
| Product Type | Ni/Pd/Au Polishing Slurry |
| Grade | Electronic/EL Grade |
| Abrasive Type | Colloidal Silica / Alumina based |
| Mean Particle Size | 50-120 nm |
| Ph Value | 3-5 (acidic) or 9-11 (alkaline, depending on formulation) |
| Solids Content | 10-30 wt% |
| Density | 1.05-1.15 g/cm³ |
| Viscosity | 2-15 mPa·s |
| Selectivity | High selectivity for Ni, Pd, and Au over underlying dielectrics |
| Surface Roughness Ra | <1 nm after polishing |
| Purity | Metal impurities <1 ppm; particle count <100 particles/ml (≥0.5 µm) |
| Shelf Life | 6-12 months at 5-25°C in sealed container |
| Dilution Ratio | 1:1 to 1:10 with DI water (depending on process) |
| Removal Rate | Ni: 100-300 nm/min; Pd: 50-200 nm/min; Au: 150-400 nm/min |
As an accredited Ni/Pd/Au Polishing Slurry Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Supplied as 1-gallon (3.78 L) quantities in sealed HDPE bottles, ensuring purity for Ni/Pd/Au polishing slurry electronic/EL grade. |
| Container Loading (20′ FCL) | 20′ FCL: UN-approved drums/pails of Ni/Pd/Au polishing slurry, electronic/EL grade, securely palletized and loaded for safe transport. |
| Shipping | Ni/Pd/Au Polishing Slurry Electronic/EL Grade is shipped as an aqueous, nonflammable liquid in sealed, contamination-free HDPE containers or drums. Protect from freezing, extreme heat, and sunlight. It generally requires no dangerous-goods declaration unless pH or metal content exceeds regulatory thresholds; verify SDS and local transport regulations before dispatch. |
| Storage | Store in a tightly sealed original container in a clean, dry, cool area (15–25°C/59–77°F) away from sunlight, heat, and incompatible chemicals. Do not freeze. Shake or roll gently before use to redistribute particles. Avoid contamination by using dedicated clean utensils. Keep container closed when not in use and follow the manufacturer’s Safety Data Sheet for shelf-life guidance. |
| Shelf Life | Shelf life typically 6 months from manufacture when stored sealed at recommended temperature, avoiding freezing and contamination. |
On 300 mm copper pillar plating lines where electroplated Cu/Ni/Au stacks are deposited for fine-pitch flip-chip interconnection, the cap layer height distribution after electroplating commonly shows edge-fast thickness variation exceeding ±0.8 µm, which forces a post-plating planarization step capable of discriminating gold, palladium, and nickel without etching the underlying copper. The slurry is blended at point of use by diluting the 30–35 wt% solids concentrate with ultrapure water at 1:2 to 1:5 volume ratio; for gold-dominant caps, hydrogen peroxide is metered into the delivery line at 0.8–1.5 wt% while the redox potential is held between 450 mV and 650 mV versus Ag/AgCl to avoid pitting of the nickel barrier. Slurry preparation, chemical distribution, and exhaust interlock architecture follow SEMI S2-0718 and SEMI S8-0718; ultrapure water quality is maintained to ASTM D5127-13 Type E-1.2, waste segregation is controlled under REACH Regulation (EC) No 1907/2006 Article 31, and final solder-capped devices are declared under RoHS Directive 2011/65/EU with process-specific exemptions assessed at the packaging level. Polishing is executed on a multizone 300 mm rotary CMP tool with a polyurethane pad of Shore D hardness 52–58, platen speed 70–95 rpm, carrier downforce 2.5–4.5 psi, and slurry flow 200–350 mL/min. Endpoint control uses eddy-current thickness monitoring with an over-polish window limited to 15–25% of the main step because the effective gold-to-nickel selectivity ratio may fall below 10:1 on high-current-density plated films; this selectivity must be re-qualified when the nickel barrier thickness drops below 1 µm. After planarization, the wafers proceed to solder paste printing or ball drop, reflow, and singulation into flip-chip ball-grid-array packages used in automotive radar transceivers and application processors.
Gold bumps electroplated on 200 mm GaAs wafers for RF front-end devices exhibit thickness non-uniformity driven by current shunting across the semi-insulating substrate and J-hook growth at the resist edge. Thermosonic wire bonding requires contact pads with a planarity deviation below 0.5 µm because the bond force window on 25 µm gold wire narrows when the bump surface carries residual ridges or edge spikes. The slurry is applied in a point-of-use blend of 1:3 concentrate-to-ultrapure-water by volume, with potassium hydroxide pH adjustment to 5.5–6.5 and 0.5 wt% hydrogen peroxide for gold removal; nickel and palladium underlayers remain passivated within this pH band. Processing on a single-side CMP tool uses a soft two-layer pad with Shore D hardness 42–48, platen speed 60–80 rpm, downforce 1.5–2.5 psi, and slurry flow 80–150 mL/min. Because GaAs has a fracture toughness below 0.5 MPa·m0.5, the carrier vacuum is reduced to −40 kPa and edge guards are installed to prevent slurry accumulation at the wafer bevel; the removal rate is intentionally kept below 300 nm/min to avoid subsurface damage. Post-polish citric acid cleaning is limited to 5–10 s to remove residual abrasive without dissolving the gold bump. Qualification follows MIL-STD-883 Method 2010.25 for wire-bond shear after encapsulation, and the tool installation operates under SEMI S2-0718; final RF modules are cycled to JEDEC JESD22-A104D to confirm package integrity. The finished wafers supply pHEMT power amplifiers, antenna switch modules, and low-noise amplifiers for mobile handsets.
In optical MEMS fabricated on bonded silicon-on-insulator substrates, sacrificial gold mirrors are deposited by electron-beam evaporation or electroplating to thicknesses of 0.8–1.2 µm, and the mirror surface roughness after deposition frequently reaches Ra 8–15 nm, which increases scattering loss beyond the 0.5% budget for interferometric readout. The slurry is diluted at 1:4 with ultrapure water and adjusted to pH 7.5–9.0 with tetramethylammonium hydroxide to suppress free gold dissolution; abrasive loading at point of use is held between 5 vol% and 10 vol%. Surface texture acceptance is specified by ISO 10110-8:2019 with an Ra target of ≤1 nm over a 50 µm evaluation length; cleanroom assembly follows ISO 14644-1 Class 5, and packaged devices are subjected to JEDEC JESD22-A104D temperature cycling. Polishing is performed on a 200 mm single-side CMP system with low downforce 1.0–1.5 psi, platen speed 40–60 rpm, and slurry flow 60–120 mL/min. A hard polyurethane pad is selected only when the mirror is supported by a full-area SiO₂ sacrificial layer; direct polishing on released structures is avoided because torsional deflection under shear exceeds the 50 nm elastic limit of the hinge layer. Residual slurry films are removed with a dilute ammonium citrate rinse of 15–30 s to prevent gold ion redeposition on exposed silicon dioxide sidewalls. Planarized mirrors are integrated into portable optical interferometers, micro-spectrometers, and LiDAR scanning mirrors.
Metallized 96% alumina and aluminum nitride substrates with sequential thick-film Ni/Pd/Au conductor layers are lapped in a double-side planetary machine to reduce local thickness variation before solder die attach. Edge effects produce a local removal rate increase of 20–40% within the outer 5 mm band when platen hardness and abrasive particle size are not matched; the slurry’s secondary-particle size is controlled to 120–180 nm D50 with a viscosity of 12–18 mPa·s by blending the concentrate 1:4 with deionized water and adding 0.3–0.6 vol% non-ionic polymer suppressant. The process operates under ISO 14644-1 Class 6 cleanroom conditions; surface texture and waviness are measured per ASME B46.1-2019, and end-use ceramic passive components are qualified to AEC-Q200 Rev D. The double-side lapper runs at platen speed 20–35 rpm and applied pressure 0.3–0.6 kg/cm² with a cast-iron platen and diamond conditioning rings; slurry is recirculated through a 10 µm filter and heat exchanger maintaining 22±1 °C. Aluminum nitride substrates require lower downforce and a pH ≥8.0 to prevent hydrolysis and ammonia evolution at exposed edges; for gold-rich top layers, the oxidizer addition is reduced to 0.2 wt% to avoid selective grain-boundary etching. The lapped substrates become RF power amplifier bases, chip attenuator terminations, and high-frequency ceramic packages for 5G base-station front-end modules.
Wafer-level vacuum encapsulation lids for MEMS gyroscopes and pressure sensors use electroplated Ni/Au seal rings around the cavity perimeter. If the as-plated ring protrudes above the cavity spacer by more than 1 µm, solder wetting during Au-Sn eutectic bonding becomes spatially non-uniform and void fractions rise above 5% in scanning acoustic microscopy. The slurry is used in a point-of-use dilution of 1:2 with ultrapure water and a hydrogen peroxide concentration of 0.3–0.8 wt%, with pH held at 6.0–7.0 to balance gold removal against nickel ring sidewall attack. Seal ring co-planarity is verified after polishing by white-light interferometry per ISO 25178-604, and the subsequent bonding process is screened by MIL-STD-883 Method 2014 die shear testing. Polishing is executed on a 200 mm CMP tool with a soft pad, platen speed 55–75 rpm, downforce 1.5–2.0 psi, and slurry flow 100–180 mL/min; endpoint is triggered by motor current change corresponding to a ring height reduction of 0.5–1.0 µm. Published removal-rate data for this specific configuration is limited; the dilution and downforce must be re-qualified when the barrier-to-gold thickness ratio changes by more than 10%. A dilute citric acid dispense step 10–20 s removes residual gold ions and prevents redeposition on the cavity oxide. The planarized lids proceed to wafer-level vacuum bonding for 6-axis inertial measurement units and barometric pressure sensors.
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Designated NPD-EL-7S in supplier documentation, the Ni/Pd/Au Polishing Slurry Electronic/EL Grade is a low-sodium, low-potassium colloidal silica dispersion intended for chemical mechanical planarization of electroless nickel, electroless palladium, and immersion or electroless gold surfaces encountered in wafer-level packaging, redistribution layers, and high-density package substrates. The ready-to-use formulation contains 5.0–7.0 wt% colloidal SiO₂ and 0.5–1.2 wt% hydrogen peroxide, with a chloride-free buffer system holding pH between 7.2 and 7.6 at 25 °C. The electronic/EL designation is defined less by abrasive activity than by contaminant exclusion: total sodium and potassium are each controlled below 100 ppb, total iron below 50 ppb, chloride below 1.0 ppm, and large particle counts at or above 0.56 µm are limited to ≤ 75 particles/mL after point-of-use filtration. These boundaries are appropriate for surfaces that subsequently undergo wire bonding or solder bump attachment, where residual mobile ions, embedded abrasive, and coarse particle deposition can reduce wire pull strength, solder wetting, and intermetallic adhesion.
The lot-release acceptance window for the product is summarized in the following table. Values are determined on the ready-to-use formulation after 24 h equilibration at 25 °C. Because dynamic light scattering is insensitive to low concentrations of coarse particles, the large particle count method is required in addition to the D50 measurement; failure to monitor the coarse tail can allow batch-to-batch shift in microscratch density even when the mean particle size remains within specification.
| Property | Acceptance window | Test method |
|---|---|---|
| Abrasive content as SiO₂ | 5.0–7.0 wt% | Thermogravimetric analysis, 105–1000 °C |
| pH at 25 °C | 7.2–7.6 | ASTM E70-19 glass electrode |
| Mean secondary particle size D50 | 30–45 nm | ASTM E2490-08 photon correlation spectroscopy |
| Particle size D90 | ≤ 80 nm | ASTM E2490-08 |
| Large particle count ≥ 0.56 µm | ≤ 75 particles/mL | Optical particle counter, ISO 21501-1:2009 calibration |
| Viscosity at 25 °C | 1.2–2.0 mPa·s | ASTM D2196-20, Brookfield UL adapter, 60 rpm |
| Density at 25 °C | 1.02–1.05 g/cm³ | ASTM D4052-18 |
| Sodium | ≤ 100 ppb | ICP-MS per ISO 17294-2:2016 after closed-vessel digestion |
| Potassium | ≤ 100 ppb | ICP-MS per ISO 17294-2:2016 |
| Iron | ≤ 50 ppb | ICP-MS per ISO 17294-2:2016 |
| Chloride | ≤ 1.0 ppm | Ion chromatography |
| Shelf life | Ready-to-use: 6 months at 5–10 °C; concentrate: 12 months at 5–25 °C | Supplier stability protocol at 5 °C, 25 °C, and 40 °C |
The specification window should not be interpreted as a universal CMP process guarantee. The required material removal rate, selectivity ratio, and post-clean defect density are stack-dependent. Published data for this specific NPD-EL-7S configuration on every packaged substrate are limited, so qualification on blanket films and patterned test vehicles is required before transfer to a production line.
No header is used here because the process context is apparent from the equipment parameters. On a production-scale 300 mm CMP tool equipped with a polyurethane pad, the slurry is typically dispensed at 100–200 mL/min onto a continuously conditioned pad. Typical process settings are downforce 1.5–3.0 psi, platen speed 60–90 rpm, and head speed 50–80 rpm. Pad temperature should be maintained between 25 °C and 35 °C; sustained operation above 40 °C accelerates hydrogen peroxide decomposition and promotes silica gel formation on the pad surface. Endpoint control is preferably by motor current or optical thickness when the underlying dielectric or barrier layer is exposed. The slurry should not be stored in dead legs or stagnant manifolds because shear-induced agglomeration and local peroxide decomposition can occur. Point-of-use filtration through a 0.5 µm membrane is required. If defect inspection shows residual coarse particles after 0.5 µm filtration, a 0.2 µm membrane may be substituted, but the filter area must be sized to maintain a clean-water pressure drop below 34 kPa at 300 mL/min.
For dilution or rinse operations, only electronic-grade water conforming to ASTM D5127-13(2018) Type E-1.2 should be used. Ordinary deionized water with higher calcium and magnesium content can destabilize the colloidal silica and increase large particle counts. The day tank and recirculation loop should be pre-cleaned with 2% citric acid solution followed by electronic-grade water until rinse conductivity is below 0.5 µS/cm. No inorganic acid should be added to raise removal rate; lowering the slurry pH below 6.0 promotes galvanic attack of electroless nickel and increases surface roughness. Likewise, amine-based pH adjusters should be avoided because they can destabilize the silica dispersion and complex palladium.
The primary difference between this electronic/EL grade and many general-purpose CMP slurries is not abrasive loading but contaminant exclusion and pH design. Generic silica slurries may contain sodium from silicate synthesis at levels above 1 ppm; this product uses high-purity, ion-exchanged colloidal silica with sodium and potassium each held at or below 100 ppb. Chloride is excluded because chloride-containing acidic gold slurries can induce pitting at the Ni–Au interface. The 7.2–7.6 pH window is selected to suppress electroless nickel undercut while avoiding the strong palladium dissolution observed in high-pH formulations above 10. The result is a formulation that polishes gold and palladium at moderate removal rates without generating the mobile ion residue that reduces wire-bond pull strength or the chloride pitting that degrades solder joint reliability.
Compared with conventional alumina-based gold-polishing slurries, the abrasive in this product is colloidal silica with a secondary particle size of 30–45 nm. Alumina has a Mohs hardness near 9, while colloidal silica is generally 6–7. On soft gold and palladium surfaces, harder alumina particles can produce microscratches and embedded-particle defects even when material removal rate remains within target. Because gold removal in CMP is strongly controlled by electrochemical oxidation rather than purely by mechanical abrasion, a lower-hardness abrasive can provide adequate removal rate while reducing scratch density. Compared with high-pH copper barrier slurries, this product operates near neutral pH and does not rely on high alkali content or aggressive copper complexing agents that would be incompatible with Ni/Pd/Au stacks.
The oxidizer concentration is deliberately limited to 0.5–1.2 wt% hydrogen peroxide. Increasing hydrogen peroxide above 1.5 wt% may raise the gold removal rate but can also destabilize colloidal silica, increase large particle counts, and accelerate pad loading. The user should not compensate for low removal rate by adding oxidizer beyond the stated window without supplier evaluation. If higher gold stock-removal is required for a thicker plated gold layer, a separate bulk gold CMP slurry should be used before final planarization with NPD-EL-7S.
Post-CMP cleaning for this slurry is typically a two-step sequence. The first step uses brush cleaning with electronic-grade water containing 0.1–0.5 vol% citric acid at pH 3–4. The second step uses megasonic rinsing in ASTM D5127-13(2018) Type E-1.2 water. Citric acid removes adsorbed silica and trace metal hydroxide residues without aggressively etching the underlying nickel. Ammonium hydroxide or amine-based post-CMP cleaners at pH above 9.0 should not be used immediately after polishing because residual hydrogen peroxide and high pH can roughen gold grain boundaries. Cleaned surfaces can be evaluated with a sessile drop contact angle goniometer at 25 °C and 50% relative humidity; a contact angle below 10° generally indicates removal of organic pad debris, while values above 20° indicate the need for a second dilute citric acid brush step.
Defect density on Ni/Pd/Au surfaces is influenced more by point-of-use filtration and pad conditioning than by the slurry mean particle size alone. The slurry must be recirculated continuously at 5–25 °C and filtered through a 0.5 µm or finer membrane at the tool. Large particle counts should be monitored at the point of use, not only at container opening, because transport and tool transfer can introduce coarse particles. Pad conditioning should use a diamond disk in situ; ex situ conditioning is acceptable only when baseline defect data show no statistically significant increase in scratch density. Post-polish defect inspection should be performed using a laser scanning wafer inspection system calibrated with 0.2 µm latex spheres. If defect density exceeds the stack-specific budget, the first corrective actions should be verification of point-of-use filter integrity, pad conditioning schedule, and rinse water conductivity rather than slurry reformulation.
Each lot is released only after a 24 h accelerated settling test at 40 °C. The acceptance criteria for this test are a D50 shift below 5 nm, pH drift below 0.2 units, and large particle count increase below 25 particles/mL above the initial value. Retention samples are held for 24 months from the date of manufacture. Containers should be stored upright and sealed after each extraction; dried silica residue on closures or container walls is difficult to remove and must be prevented rather than reworked.
