Cobar 390-RX-HT Flux
High-Reliability No-Clean Wave Soldering Flux
Cobar 390-RX-HT is a high-performance, alcohol-based liquid wave soldering flux engineered for high-reliability and lead-free electronics assembly. Formulated as a true No-Clean solution with a synthetic filmformer, it leaves behind safe, non-corrosive residues while actively reducing soldering defects like bridging and solder balling during high-temperature operations.
Process Optimisation
No-Clean Chemistry
Classified under IPC-ANSI-J-STD-004 as REL0. Halide-free formulation eliminates the need for post-solder aqueous or chemical cleaning steps.
Thermal Stability
Excellent performance across ambient and nitrogen (N2) lead-free processes. Specially qualified for multi-layer boards and wave soldering machines. An excellent choice for SN100C
Yield Maximisation
Chemically engineered to reduce skipped joints, eliminate solder balling, prevent bridging, and promote optimal hole wicking.
390-RX-HT Technical Specifications
| Specification Parameter | Data Value / Compliance |
|---|---|
| Flux Classification | IPC/ANSI J-STD-004: REL0 | ISO 9454-1: 1.2.3.A |
| Specific Gravity (20 °C) | 0.813 kg/dm³ (+/- 0.5%) |
| Solids Content | 2.20% w/w |
| Acid Number | 15.80 mgKOH (+/- 2.5%) |
| VOC Content | 92.00% w/w |
| Filmformer Base | Synthetic |
| Flashpoint (COC) | 12.4 °C |
| Compatible Thinner | Cobar Thinner 425-00 |
Application & Compatibility
Application Methods +
Foam & Nozzle Spray: This flux is ideally suited for both foam fluxing and automated nozzle-spray fluxing systems. It accommodates a moderate preheat cycle and a short contact time with molten solder.
PCB Surface Finishes +
Broad Compatibility: Fully compatible with industry-standard pad finishes including Immersion Tin (Sn), Organic Solderability Preservatives (OSP), Ni/Au (ENIG), Ni/Pd, and Immersion Silver (Ag).
Industry & Testing Compliance +
Hi-Rel Electronics: Qualified under Telcordia/Bellcore TR-NWT-000078/3 standards. It is completely compatible with In-Circuit Compatibility Testing (ICCT) and post-reflow conformal coating processes.
Cobar 390-RX-HT Flux FAQ
Is Cobar 390-RX-HT suitable for lead-free selective soldering lines? +
No, Cobar 390-RX-HT is engineered specifically for automated wave soldering applications. It is not recommended for selective soldering equipment. For selective lines, a low-VOC drop-jet flux like Cobar 94-SEL should be used to ensure controlled deposition and avoid nozzle blockages or unsafe residue spreading.
Does a REL0 classified flux require post-solder cleaning? +
No, post-solder cleaning is not recommended. Under the IPC J-STD-004 standard, a REL0 classification identifies a resin-based, halide-free formulation. The remaining synthetic residue forms a benign, non-conductive, and non-corrosive barrier that should be left on the PCB. Attempting to wash it with standard water processes can actually degrade the film properties.
How do you prevent solder ball defects during high temperature wave processes? +
Preventing solder balls requires maintaining stable flux density and strict preheat management. Cobar 390-RX-HT is chemically balanced with a 92% VOC alcohol carrier that vaporises smoothly under preheaters. This leaves a uniform solids layer before the PCB contacts the molten wave, reducing the explosive outgassing that drives solder ball creation.
What thinner should be used with Cobar 390-RX-HT to maintain specific gravity? +
Cobar Thinner 425-00 is the factory-recommended solvent formulated specifically for this liquid flux line. During extended wave soldering production cycles, the alcohol vehicle naturally evaporates, causing the specific gravity to climb above the nominal 0.813 kg/dm³. Regularly adding Thinner 425-00 safely restores the required 2.20% solids concentration without disrupting or destabilising the underlying synthetic resin chemistry. Note: This thinner is not supplied directly on our store and should be purchases directly from Balver Zinn.