Sheet Metal Fabrication Technical Tips for Soldering

TECHNICAL TIPS FOR SOLDERING

Common Solder Alloys and Their Uses in Roofing

Solder is a fusible metal alloy (combination of metals) used to join together metal work pieces which has a melting point Soldering Iron Types below that of the work piece(s). Solder is a low-melting alloy commonly based on lead and tin used for joining less fusible metals such as copper and zinc.

Alloys of lead (chemical symbol Pb) and tin (chemical symbol Sn) have been universally used in the past, and are still readily

available; they are particularly convenient for hand-soldering. The tin/lead solders or “soft solder” is typically the materials STANDARD SOLDERING IRONS USE LP GAS, IGNITE that are thought of when solder or soldering is mentioned. MANUALLY WITH A STRIKER AND CONNECT WITH A These soft solders have a typical melting range between 90 and STANDARD POL CONNECTION TO ANY DOT 450 °C (190 to 840 °F). They are commonly used in electronics, PROPANE TANK OR WITH A WORTHINGTON plumbing, and assembly of sheet metal parts. REGULATOR TO ANY WORTHINGTON TANK

Tin/lead solders are commercially available with tin concentrations between 5% and 70% by weight. The 63/37 lead/tin alloy is most commonly used for roofing work in Europe, the 50/50 alloys are more common in North America. Both alloys are “eutectic alloys” which means:

PREMIUM IRONS USE LP GAS, HAVE A BUILT IN PIEZO IGNITERS AND CONNECT WITH A STANDARD • They have lower melting points, between 360 and 370 °F POL CONNECTION TO ANY DOT PROPANE TANK OR and WITH A WORTHINGTON REGULATOR TO ANY WORTHINGTON TANK • The melting point is truly a point — not a range

When a higher proportion of lead is used (67/33 versus 50/50) the higher proportion of lead creates the advantage of making the alloy solidify more slowly, so that it can be “wiped” over the joint to ensure water tightness, the joints being

physically fitted together before soldering. The greater the tin concentration, the greater the solder’s tensile and shear SELF CONTAINED PREMIUM IRONS USE A strengths. Higher proportions of tin—more expensive than PROPANE/PROPENE GAS MIXTURE, HAVE A BUILT lead, also improve the wetting properties of the alloy as IN PIEZO IGNITER AND A SMALL PROPANE/PROPENE lead itself has poor wetting characteristics. GAS CANISTER IN THE HANDLE

SHEET METAL FABRICATION TECHNICAL TIPS FOR SOLDERING

Common Solder Alloys

Common Lead Tin Other Description Solder Alloys

Pb75Sn25 75 25 Crude solders AKA "Plumber’s solder" for construction plumbing works, flame- Pb70Sn30 70 30 melted. Used for soldering car engine radiators. Also used for machine, dip and hand soldering of plumbing fixtures and fittings. Superior body solder (auto) Pb68Sn32 68 32

Sn30Pb50Zn2 50 30 20% Zinc Zinc containing solders ( such as Kapp Galvrepair®) are economical solders for 0 repairing & joining most metals including Zinc, Galvanized Steel, Galvanized Sn33Pb40Zn2 40 32 28% Zinc Aluminum, Aluminum and cast Iron. 8 Crude solder for construction plumbing and roofing – more frequently used by Pb67Sn33 67 33 Europeans than 50/50. Ordinary solder for soldering of brass, coper and zinc. General purpose, for Sn Pb 50 50 50 50 standard tinning and sheet metal work. More common in North America.

Lead-free solders

Lead-free solder is somewhat less convenient for hand-soldering and is often used to avoid the environmental effect of lead. Lead Free Solders for roofing are typically a minimum of 95.5% Tin with small amounts of Silver, Antimony and/or Copper.

The reason lead free solders have been introduced into the roofing industry is that the electrochemical couple of copper and lead promotes corrosion of the lead. Since even small amounts of lead have been found detrimental to health, lead in solders can be replaced by silver or antimony, often with small amounts of copper included.

When using lead free solders, be aware that these solders are prone to forming microscopic cavities in the solder called “Kirkendall voids”. When two different types of metal that are in contact are heated, dispersion of the soldering metal occurs (called the Kirkendall effect). Repeated thermal cycling causes the formation of voids which may lead to solder cracks. Lead-free solders can lead to shorter life cycles of the finished products.

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