| HS Code | 897543 |
| Product | MacDermid SMB-100 Solder Mask Bridge Agent (Electronic/EL Grade) |
| Physical Form | Liquid |
| Appearance | Clear, colorless to pale yellow homogeneous liquid |
| Grade | Electronic/EL Grade |
| Odor | Mild, low odor |
| Ph | 7.0–8.5 |
| Specific Gravity | 1.00 ± 0.02 at 25°C |
| Viscosity | 10–30 cP at 25°C |
| Flash Point | > 100°C |
| Water Solubility | Fully miscible in water |
| Shelf Life | 12 months from date of manufacture |
| Recommended Storage Temperature | 5–35°C |
As an accredited Solder Mask Bridge Agent (MacDermid SMB-100) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Packaged in a 1-gallon leak-proof HDPE bottle with tamper-evident cap and safety labeling. Quantity: one gallon. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Solder Mask Bridge Agent (MacDermid SMB-100), Electronic/EL Grade, packed and secured per regulations. |
| Shipping | Ship as regulated chemical in UN-approved, leak-proof, corrosion-resistant containers with complete hazmat documentation and hazard labels. Keep upright, protected from damage, and segregated from incompatible materials per DOT/IATA/IMDG. Verify current shipping restrictions for MacDermid SMB-100 Electronic/EL Grade before dispatch. Use trained hazmat personnel and follow all applicable regulations. |
| Storage | Store in tightly sealed original containers in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, and oxidizing agents. Maintain temperatures between 15–30°C and avoid freezing. Keep containers upright to prevent leakage. Ensure good ventilation, prohibit smoking, and separate from incompatible chemicals. Always follow manufacturer expiration and handling guidelines. |
| Shelf Life | The shelf life is generally 6 months when stored in the original sealed container under recommended conditions, below 25°C. |
On HDI smartphone main-board production lines where solder mask dams are printed between 0.4 mm pitch chip-scale package lands and 0.3 mm pitch microvia arrays, MacDermid SMB-100 is introduced as a pre-dispersed electronic/EL-grade additive at 1.0–2.5 wt% of total LPI ink weight. Loadings above 2.5 wt% in production lots raise Brookfield viscosity at 10 rpm from 180 Pa·s to 240 Pa·s and reduce sidewall undercut after developing to 8–12 µm. Qualification for this segment is governed by IPC-SM-840E adhesion and thermal stress methods, UL 94V-0, RoHS 2011/65/EU Annex II, and REACH SVHC screening. Cross-hatch adhesion is measured according to IPC-TM-650 2.4.28.1, thermal stress at 288 °C for 10 s, and surface insulation resistance after 85 °C/85% RH for 1,000 h is tested under IPC-TM-650 2.6.3.7. The downstream production process begins with double-sided screen printing using 77–120 threads/cm stainless steel mesh, a one-pass wet film thickness of 18–25 µm, and an oven pre-bake at 75 °C for 40 min to achieve touch-dry tack; if shop-floor relative humidity exceeds 60%, the panels are pre-baked at 80 °C for 20 min to prevent microvoid formation. Imaging proceeds on laser direct imaging equipment with 405 nm output and 120–180 mJ/cm² exposure dose. Development in a three-chamber spray conveyor using 0.8–1.0 wt% sodium carbonate at 30 °C clears unexposed regions while the bridge agent reduces polymer swelling in the exposed network. Final cure in a forced-air convection oven at 150 °C for 60 min produces a crosslinked film with pencil hardness 6H and adhesion 4B per ASTM D3359-17. Finished assemblies are rigid FR-4 HDI smartphone main boards and carrier modules for application processors, where the cured film must survive reflow peaks at 260 °C per J-STD-020E and maintain SIR above 1 × 10⁸ Ω.
In fine-line FC-BGA package substrate manufacturing, the bridge agent is compounded into high-resolution LPI ink at 2.0–3.5 wt% of total formulation. Viscosity is adjusted to 90–130 Pa·s at 25 °C on a rheometer with 25 mm parallel plates at 10 s⁻¹; excess loading increases yield stress above 45 Pa and slows levelling on ABF build-up surfaces. The compliance framework includes IPC-SM-840E, UL 94V-0, and IATF 16949:2016 process control for automotive-qualified substrates, with package-level thermal shock evaluated by IEC 60068-2-14:2009. Downstream processing begins with spray or curtain coating onto 10–18 µm copper-clad ABF build-up films at conveyor speeds of 1.2–1.8 m/min, followed by vacuum pre-bake at 80 °C for 30 min. LDI exposure at 405 nm with dose 180–250 mJ/cm² defines 15–20 µm line/space openings over bump pad metallization. Development is performed in a horizontal conveyorized spray chamber using 0.7–0.9 wt% Na₂CO₃ at 28 °C with 45 s contact time and a post-develop DI rinse at 0.15 MPa; via openings are verified by scanning electron microscopy before plasma descum at 200 W in argon/oxygen for 2 min. Final thermal cure is 170 °C for 30 min under nitrogen to reduce copper oxidation. The resulting film thickness of 8–12 µm over circuits passes IPC-TM-650 2.4.28.1 tape adhesion and shows no delamination after 288 °C / 10 s solder float. Terminal products are FC-BGA substrates for graphics processors and network switch ASICs with solder mask dams between 60 µm pitch flip-chip bump pads; post-cure outgassing must remain below 0.1% mass loss by ASTM E595-15 to avoid underfill voiding.
Production of engine-control and transmission-control modules requires solder mask that resists thermal shock from -40 °C to 150 °C under IEC 60068-2-14:2009, test Na, with 30 min dwell and 1,000 cycles; the bridge agent is compounded at 1.5–3.0 wt% of wet LPI ink to preserve adhesion after repeated thermal cycling. Qualification follows IPC-SM-840E, UL 94V-0, RoHS 2011/65/EU, and IATF 16949:2016, with chemical resistance assessed by blistering ratings per ISO 4628-1 after 5 wt% NaCl neutral salt spray at 35 °C for 500 h per ISO 9227:2017. The downstream process begins with double-sided screen printing on 1.6 mm FR-4 laminates using 100–150 mesh stainless screens and 65–75 Shore A squeegees, producing 20–30 µm wet film thickness. Panels are pre-baked at 75 °C for 45 min, exposed through glass photomasks with 365 nm UV at 300–400 mJ/cm², and developed in 0.9–1.1 wt% Na₂CO₃ at 30 °C for 50 s. Mixed ink is used within 8 h at screen feed lines to avoid viscosity drift beyond 5%. The final cure at 150 °C for 60 min is followed by electrical test and conformal coating with polyurethane or silicone. Cured films show cross-hatch adhesion 4B per ASTM D3359-17 and pencil hardness 6H, with no visual cracks or blisters after thermal shock. Terminal products are engine control units and transmission control modules mounted in under-hood environments, where exposed solder mask areas adjacent to high-density connectors and press-fit pins must withstand immersion in automatic transmission fluid at 125 °C for 1,000 h without surface softening.
When polyimide flex carriers are processed in reel-to-reel solder mask lines for folded camera modules, the bridge agent is metered into flexible LPI ink at 2.0–3.0 wt% to maintain post-cure elongation of 8–15% measured by ASTM D638-14 on free films and a mandrel bend crack radius below 2.0 mm per ASTM D522-17. The compliance framework includes IPC-SM-840E flexible solder mask, UL 94V-0, REACH SVHC, and IEC 61249-2-21 halogen-free material declaration. Downstream processing uses roll-to-roll screen printing or slot-die coating on 25 µm and 50 µm polyimide films, with wet thickness controlled to 12–20 µm and a pre-bake at 80 °C for 20 min in a conveyorized IR oven. UV exposure through a phototool at 365 nm and 150–250 mJ/cm² is followed by development in 0.8 wt% Na₂CO₃ at 28 °C and final thermal cure at 145 °C for 40 min; cure temperature above 180 °C oxidizes polyimide, and published data for this specific configuration is limited below 135 °C. The bridge agent reduces brittle crosslink density in the cured film, permitting repeated flexing at 106 cycles with 2.5 mm radius in a flexural endurance tester without cracking. Terminal products are flexible printed circuits for compact camera actuators, OLED display interconnects, and dynamic hinges, where solder mask is printed over copper traces with 100 µm pitch and folded at 180°.
In RF power amplifier and antenna-in-package board processes, the additive is used at 1.0–2.0 wt% to minimize attack of cured solder mask by electroless nickel immersion gold plating solutions held at 82–88 °C and pH 4.6–5.2; compliance is verified by IPC-SM-840E chemical resistance and ASTM B735-16 porosity testing after 30 min immersion. The production sequence includes screen printing on low-loss hydrocarbon ceramic laminates, pre-bake at 70 °C for 30 min, UV imaging, developing with 0.8 wt% Na₂CO₃, and final cure at 155 °C for 60 min before ENIG plating. Premix handling excludes amine-based latent catalysts because the system shows viscosity increase above 25% within 4 h of ambient storage. Terminal products are RF power amplifier boards and antenna modules with solder mask dams separating 0.5 mm pitch QFN pads.
When outdoor LED lighting modules are built on aluminum metal-core laminates with thermal conductivity of 2.0–3.0 W/m·K, the bridge agent is added at 1.0–2.5 wt% to maintain white solder mask reflectivity above 85% at 450 nm after 1,000 h of damp heat at 85 °C/85% RH, measured by integrating sphere reflectance per CIE 130-1998. The compliance framework includes IPC-SM-840E, UL 94V-0, RoHS 2011/65/EU, and photobiological safety evaluation under IEC 62471. Downstream processing consists of screen printing on anodized aluminum substrates with 120 mesh screens and 25–35 µm wet film thickness, pre-baking at 75 °C for 30 min, UV exposure at 365 nm with 250–350 mJ/cm², development in 0.8 wt% Na₂CO₃ at 28 °C, and final thermal cure at 150 °C for 45 min. The bridge agent suppresses yellowing by stabilizing the acrylic network during repeated thermal cycles from -20 °C to 100 °C. Terminal products are outdoor LED street-lamp arrays and architectural linear fixtures with die-cast aluminum housings, where the cured white solder mask serves both as reflective layer and electrical isolation.
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In high-density interconnect fabrication, the term solder mask bridging describes the retention of a continuous LPI dam between adjacent pads or between pad and trace after alkaline development and final cure. MacDermid SMB-100 Electronic/EL Grade is supplied as a liquid bridge-control additive for liquid photoimageable solder mask formulations; it is added to the ink before coating rather than applied as a post-develop repair. Published independent data for this specific formulation are limited, and the manufacturer’s certificate of analysis is the controlling document for batch-specific viscosity, density, and ionic residue values. The product is positioned as an electronics-grade processing aid intended to alter the balance among low-shear structure, surface tension, and alkaline developer solubility that determines whether a narrow solder mask dam survives development without leaving residual webs in unintended locations.
Electronic/EL grade in LPI processing is primarily a residue and purity classification. After cure, residual ionic contamination from solder mask and flux systems is commonly extracted in a 75/25 isopropanol/deionized water solution and measured by resistivity using IPC-TM-650 2.3.25. Acceptance targets referenced in J-STD-001 for high-reliability assemblies are 1.56 µg NaCl equivalent/cm². A bridge additive qualified for this application must not contribute mobile halide, alkali metal, or conductive surfactant residues above that assembled-board allowance. The grade therefore avoids hydrochloric acid salts, sodium-based buffers, and non-volatile ionic surfactants in the formulation. Batch-specific ionic cleanliness for SMB-100 should be verified from the certificate of analysis rather than inferred from commodity surface-tension reducers.
In the coating path, SMB-100 is blended into the finished LPI ink after pigment dispersion is complete. A high-shear cowles disperser or planetary mixer is operated until the additive is fully incorporated; entrained air is then removed by vacuum degassing below 100 mbar absolute pressure to prevent bubbles from forming pinholes during screen printing. The pre-dry step, typically run between 35 °C and 75 °C with a tunnel residence of 30–90 min depending on panel thickness and rack loading, controls the solvent-free tack and the oxygen concentration at the photopolymer surface. SMB-100 does not remove the need for tack-dry control; retained solvent above the base resist supplier’s limit can cause photomask sticking and poor resolution.
The functional requirement for a solder mask bridge agent is not a single viscosity increase. A material that only raises low-shear viscosity can preserve intentional bridges but may increase sidewall residue if developer spray pressure is not adjusted. A material that only lowers surface tension can improve wetting but floods narrow gaps and destroys the dam. SMB-100 is described in product literature as a bridge-control agent, placing it in the class of additives designed to shift developer solubility and surface energy together. The numerical split between rheological and surface energy contributions is not disclosed in publicly available technical bulletins, so the product’s response must be characterized on the target resist and board finish.
Surface-active additives containing polydimethylsiloxane can migrate to the cured mask surface and create local dewetting or skip plating in electroless nickel immersion gold and electroless nickel electroless palladium immersion gold process trains. On fine-pitch QFP and 01005 component footprints, palladium activation and nickel deposition are sensitive to sub-monolayer organic contamination. For this reason, bridge-control additives intended for ENIG-compatible LPI processing are often formulated without PDMS. The silicone status of SMB-100 should be confirmed by the supplier’s batch documentation or by Fourier-transform infrared spectroscopy and time-of-flight secondary ion mass spectrometry if the manufacturing line maintains a strict no-silicone policy.
Compared with fumed silica thixotropes used for anti-settling and bridging, SMB-100 is not listed as a particulate thixotrope. Fumed silica builds low-shear viscosity through hydrogen-bonded networks; at high shear during screen printing, those networks break down only partially, and mesh openings below 180 µm can exhibit plugging. A liquid bridge-control additive reduces the required thickener loading and helps preserve filtration behavior. The limitation is that liquid additives can plasticize the cured film if overdosed, lowering glass transition temperature and solvent resistance. Therefore the supplier’s recommended loading window is narrow and should be verified by differential scanning calorimetry and solvent rub testing on the final cured film.
| Additive class | Primary mechanism | Typical process risk | Reference method |
|---|---|---|---|
| Fumed silica thixotrope | Hydrogen-bonded network build at low shear | High-shear viscosity retention and screen mesh plugging | ASTM D2196 |
| Silicone surface tension reducer | Surface energy lowering and flow into narrow gaps | Surface migration, ENIG skip plating, adhesion loss | Water break-free; IPC-TM-650 2.4.1.6; XPS/TOF-SIMS |
| SMB-100 Electronic/EL Grade | Product literature lists bridge-control function; mechanism inferred as combined rheology and solubility modification | Overdosage can plasticize cured film; underdosage may not retain narrow webs | Product certificate; ASTM D2196; IPC-SM-840 |
For production-scale low-shear viscosity measurement, rotational viscometry at 25 °C with a defined spindle and speed, typically 10–50 rpm, is used to monitor batch-to-batch consistency after SMB-100 addition. A viscosity shift outside the base resist control limits should not be compensated with solvent beyond the supplier’s stated maximum, because this changes pre-drying kinetics and final film thickness. High-shear response is evaluated by cone-and-plate rheometry or capillary methods; this data supports screen printer setup and confirms whether the additive has introduced unwanted dilatancy that could reduce open area transfer.
The cured solder mask must survive a lead-free reflow thermal profile with a peak temperature of 245–250 °C without blistering, discoloration, or loss of surface insulation. Solder mask formulations are qualified under IPC-SM-840 for thermal stress, dielectric strength, and moisture and insulation resistance. A bridge additive that reduces crosslink density or introduces hydrophilic moieties may pass the initial cure check but fail post-HAST insulation resistance at 85 °C/85% RH with 55 V DC bias. The Electronic/EL grade is therefore selected for low moisture uptake and minimal extractable alkaline ions.
During UV exposure, the solder mask crosslinks through free-radical polymerization of acrylate monomers in the exposed areas; the unexposed dam between fine-pitch features remains soluble in the alkaline developer. A bridge agent that carries strongly absorbing chromophores can reduce photospeed at the bottom of the film, leading to undercut or to incomplete development in narrow channels. For this reason, materials in this class are designed with minimal absorbance in the 365–405 nm range. Actual photospeed for SMB-100 is not independently published; the effect should be evaluated with an exposure energy matrix on a photoresist film thickness step wedge before production commitment.
Developer spray parameters are determined by the base resist system. A bridge-control additive can shift the development time by modifying the solubility of the unexposed dam. The correct response is not to apply a uniform increase in conveyor speed; rather, the development window is mapped by checking the minimum and maximum development times that produce clean channels without removing intended dams. This mapping is conducted with the target spray manifold pressure and developer concentration, commonly 0.8–1.2% sodium carbonate by weight for carbonate developers, but the exact chemistry depends on the resist supplier.
Post-cure thermal crosslinking is affected by the additive’s reactive or non-reactive character. If the additive is non-reactive and remains in the film as a plasticizer, it can lower glass transition temperature and increase moisture absorption. If it is reactive and consumes crosslinking sites, it can reduce solvent resistance when over-dosed. Differential scanning calorimetry on the cured film can be used to confirm glass transition temperature is within the base resist supplier’s acceptance band. The supplier’s loading range for SMB-100 should be treated as a process specification, not a starting point for experimentation.
| Qualification attribute | Reference method or standard | Control requirement |
|---|---|---|
| Low-shear viscosity after mixing | ASTM D2196 | Log shift from base ink |
| Ionic contamination after cure | IPC-TM-650 2.3.25 | J-STD-001 threshold 1.56 µg NaCl equivalent/cm² |
| Tape adhesion after thermal stress | IPC-TM-650 2.4.1.6 | No peel beyond control |
| Moisture and insulation resistance | IPC-SM-840 | Pass after 85 °C/85% RH |
| Surface silicone detection | FTIR or TOF-SIMS | Batch documentation if no-silicone line |
On automatic screen printers, the effective viscosity under squeegee shear depends on squeegee durometer, flood pressure, and snap-off. A bridge agent that lowers high-shear viscosity too much can cause the wet film to flow back into the gap after screen separation. A bridge agent that leaves the wet film too structured can create edge peaks and air entrapment. For fine-pitch solder dams, process engineering uses a multifactorial design of experiments that includes SMB-100 concentration, squeegee speed, mesh count, and pre-dry temperature. Published data for this specific configuration are limited; process-of-record development on the target panel finish is required.
Bridge-control additives should not be confused with mineral oil defoamers or mercapto-based adhesion promoters. A mineral oil defoamer can reduce bubbles during screen printing but may migrate to the surface and create wetting defects during ENIG. A mercapto-based adhesion promoter can improve copper-resist adhesion but does not address inter-pad webs. SMB-100 is supplied for bridge-control function specifically; use outside that application class requires separate validation under the acting process specification.
Solvent resistance is commonly checked by a solvent rub test using a defined solvent and a 500 g weight; the number of rubs to breakthrough is compared against the base resist control. If SMB-100 reduces the rub count relative to the control by more than the supplier’s specified margin, the concentration should be reduced within the allowed range. This test is a practical screening tool; it does not replace qualification under IPC-SM-840.
Production-scale failure modes observed with bridge-control additives in LPI include partial web retention after developing, developer scum in narrow channels, post-solder mask adhesion loss measured by tape pull, and skip plating in ENIG when surface-active species migrate. The first two are assessed on first article panels before volume coating; the third is monitored by tape adhesion per IPC-TM-650 2.4.1.6; the fourth is best detected by a water break-free test on the cured mask and by selective ENIG deposition checks on a solder dam panel.
The material should be handled in accordance with the safety data sheet. Because it is a liquid organic additive, it should be stored away from open flames, oxidizers, and moisture. If the product freezes or undergoes phase separation, the manufacturer’s rework procedure should be followed; mechanical mixing must not be used to cover a phase split that indicates chemical instability. Storage should be in a dry, cool environment, typically below 35 °C, and away from UV and visible light sources that could initiate photopolymerization. Product packaging, container size, and shelf life are not specified in this bulletin; the supplier’s logistics documentation should be consulted.
SMB-100 is not a replacement for correct exposure dose, developer nozzle pressure, or cleanroom humidity. In ultra-fine-line applications below 50 µm line/space, published performance data for this specific product are limited. The product should not be combined with strong amine-containing additives without first confirming compatibility, because amine groups can accelerate carboxylate-resin interactions and shift the alkaline development window.
