Low Melt Solder Paste
Precision Soldering at Lower Temperatures – Sn42 / Bi58 • 138°C Melting Point
Precision low-temperature solder paste engineered for professional electronics repair and rework.
Lower Temperature.
More Control.
Heat management is an important part of electronics repair. Excessive or prolonged heat can place unnecessary thermal stress on circuit boards, pads, connectors, and nearby components. PolarTronix Sn42/Bi58 solder melts at approximately 138°C, making it especially useful for controlled rework, component removal, and applications where reducing processing temperature is beneficial.
A low-temperature eutectic solder alloy designed for specialized electronics rework and applications where reduced heat exposure is preferred.
A common eutectic tin-lead solder alloy used for general electronics soldering and board-level repair at a higher melting temperature.
Melting point is the temperature at which the solder alloy transitions to liquid. Actual hot-air, soldering iron, or reflow settings may be higher and will vary depending on PCB thermal mass, component size, airflow, equipment, and the repair process.
Designed for Controlled
Electronics Rework.
PolarTronix Low Melt Solder Paste is designed for technicians who need greater control over heat during board-level repair and rework. Its 138°C melting point makes it especially useful in applications where reducing unnecessary thermal exposure is beneficial.
Component Removal
Lower-temperature solder can assist during component removal and rework by reducing the temperature required to reach a molten solder state, helping technicians work with greater control.
Heat-Sensitive Rework
Useful for repair procedures where limiting unnecessary thermal exposure to the PCB, solder pads, connectors, or nearby components is an important consideration.
Connectors & Ports
Well suited for controlled rework involving PCB-mounted connectors, ports, and other components with multiple solder joints where careful heat management is required.
Microsoldering & PCB Repair
A practical option for professional technicians performing detailed board-level repairs on smartphones, game consoles, laptops, tablets, and other modern electronics.
Low-melt solder is a specialized material and should be selected according to the component, original solder alloy, operating conditions, and requirements of the repair.
What Makes Sn42/Bi58
Different?
PolarTronix Low Melt Solder Paste uses a eutectic Sn42/Bi58 alloy composed of 42% tin and 58% bismuth. This specific composition provides a defined melting point of approximately 138°C, making it well suited for specialized low-temperature electronics rework.
What Does “Eutectic” Mean?
A eutectic solder alloy transitions between solid and liquid at a defined temperature rather than softening gradually across a broad temperature range. For Sn42/Bi58, that transition occurs at approximately 138°C.
Why It Matters
The lower melting point allows technicians to perform certain soldering and rework procedures with reduced processing temperatures compared with many conventional electronics solder alloys.
The lower melting temperature of Sn42/Bi58 can be advantageous during controlled rework, but solder selection should always consider the original alloy, operating temperature, mechanical requirements, and intended use of the repaired assembly.
Low-Melt Solder Is a
Specialized Material.
The lower melting temperature of Sn42/Bi58 can provide important advantages during certain electronics repair and rework procedures, but low-melt solder should not automatically be treated as a direct replacement for every conventional solder alloy.
Select the Alloy for the Application
Tin-bismuth solder alloys have different thermal and mechanical characteristics than conventional tin-lead and higher-temperature lead-free solder alloys. Before using Sn42/Bi58 as part of a permanent solder joint, consider the original solder alloy, operating temperature, mechanical requirements, and expected service conditions of the assembly.
Consider the End Use
Evaluate whether a low-temperature Sn42/Bi58 solder joint is appropriate for the device’s expected operating conditions and intended application.
Know the Existing Solder
Consider the original solder alloy already present on the assembly when selecting a material for repair, rework, or component replacement.
Avoid Excessive Paste
Apply only the amount required for the soldering area. Controlled application can help reduce bridging, excess residue, and inconsistent solder joint formation.
Control the Process
Adjust temperature, airflow, heating time, and technique according to the PCB, component size, thermal mass, and equipment being used.
PolarTronix Low Melt Solder Paste is intended for controlled electronics soldering and rework. Proper material selection, surface preparation, application, and process control remain essential to achieving consistent results.
Built for
Professional Repair.
PolarTronix Low Melt Solder Paste combines a lead-free Sn42/Bi58 alloy with a 138°C melting point for controlled low-temperature soldering and professional electronics rework.
Technical
Specifications.
Key product information for PolarTronix Low Melt Solder Paste, a lead-free Sn42/Bi58 solder paste designed around a 138°C melting-point alloy.
Storage & Handling
Follow the product SDS and applicable workplace procedures when storing and handling Low Melt Solder Paste.
Keep Below 30°C
Store in a cool, ventilated location where the temperature does not exceed 30°C.
Keep Sealed
Keep the product container properly sealed when not in use.
Avoid Direct Sunlight
Protect the product from direct sunlight during storage.
Cool & Ventilated
Store in an appropriately ventilated area and away from incompatible materials identified in the SDS.
Always review the current Safety Data Sheet before use. Product specifications describe the material and should not be interpreted as universal soldering, hot-air, or reflow equipment settings.