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R‑TECH cored solder wire offers a comprehensive selection of both lead-free and leaded options designed for industrial use. Each product in the range is chosen to deliver consistent, high‑quality soldering performance. Multiple flux formulations are available to suit different applications, including low‑residue, halide‑free and rosin‑free variants.
The rosin‑free solder contains no resin acids, pine derivatives or similar natural substances, helping to minimise the risk of occupational asthma in industrial settings. As with all R‑TECH solutions, support is available for selecting the most suitable product, including recommendations, guidance and sample provision. Rapid’s support team can also supply tailored pricing packages.
Standards
Fluxes used in cored solder wire and solder paste are governed by IPC standard J‑STD‑004B, widely used across the UK and Europe and comparable to DIN EN 61190‑1‑1. Flux types are identified by a four‑character code (two letters, one letter, then a number), which indicates the flux base, its activity level and whether halides are present.
Virgin material
All solder in the R‑TECH J‑STD series is manufactured exclusively from 100% virgin metal. This ensures reliable performance, especially in demanding environments or applications where safety and durability are critical.
Metallic compounds
SC100e
Advantages:
More cost‑effective than alloys containing silver
Offers good performance for general‑purpose, non–mission‑critical soldering where extreme mechanical strength isn’t required
Limitations::
Reduced wetting performance compared to alternative alloys
Slower joint formation
When soldering onto gold‑plated pads, the extended formation time can result in a noticeably dull finish
SAC305
Advantages:
Silver content enhances joint strength
Better resistance to thermal fatigue
Superior wetting and faster joint formation
Limitations:
Silver levels above 3% (e.g., premium lead‑free alloys) can lead to cracking and reduced drop/shock resistance
Increased oxidation and dross formation, which shortens solder tip life (dross is particularly problematic in wave soldering, less so when soldering by hand)
Flux types
The flux contained within the core of solder wire removes surface oxidation, improves wetting and supports proper joint formation. Without effective flux, achieving a reliable solder joint becomes difficult. It also helps protect the joint area from re‑oxidising during heating, ensuring cleaner, stronger and more consistent results.
Lead‑free solders operate at higher temperatures and generally wet less readily than traditional leaded alloys, so they require more active flux formulations. As a result, choosing the right flux type is just as important as selecting the correct alloy, especially for demanding applications or environments where joint reliability is critical.
Flux identification codes
First two letters – Flux base:
RO = rosin
RE = resin
OR = organic
IN = inorganic
Third letter - Activity level:
L = low
M = moderate
H = high
Final number - Halide content:
0 = <0.05% halides (“halide‑free”)
1 = halide content varies by activity level:
Any combination is possible, including ROL0, REM1 or ORH0.
Flux bases
Rosin fluxes
The terms rosin and resin are often used interchangeably, with manufacturers applying their own distinctions. Typically, a flux is described as rosin-based if it uses natural rosin as the primary vehicle. Some suppliers reserve the term for traditional military‑grade compositions (R, RMA, RA), labelling others simply as resin.
Fumes from rosin during soldering can trigger occupational asthma in sensitive individuals, though the specific trigger component is not fully understood.
Synthetic resin fluxes
Synthetic resin fluxes are formulated from engineered resins - commonly esters of polyols and fatty acids. These blends usually produce less odour and leave less tacky residue, although their activity and solubility are generally lower compared to natural rosin‑based fluxes.
Flux activity levels
LO:
Used mainly for Class 3 (high‑reliability / harsh environment) and Class 2 (dedicated service) electronics.
L1:
Contains small amounts of halide (up to 0.5%). Commonly used in Class 2 assemblies.
M1:
Used mainly for Class 3 (high‑reliability / harsh environment) and Class 2 (dedicated service) electronics.
What this means for your workflow
R‑TECH solder wire combines reliable metallurgy, consistent flux performance and compliance with industry standards, making it suitable for a wide range of industrial soldering tasks. Whether you need lead‑free, rosin‑free or specialist alloys, the R‑TECH range provides options to support both general‑purpose and high‑reliability applications. If you’re looking to improve technique, our soldering tips guide and ultimate guide to soldering can help you get the best results. Or simply explore the products below to find the formulation that best fits your requirements.
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