Lead Solder and Lead-Free Solder Standards

Solder is the glue that holds electronics together and often carries information and power as well.
Solder is the glue that holds electronics together and often carries information and power as well. | Source

Introduction

Solder is used to glue electronic components onto circuit card assemblies.

Solder for electronics was originally a lead alloy, but environmental concerns have led to the development of lead-free solder. There are standards for lead and lead-free solder used in the manufacture of cell phones, computers, toys and industrial equipment.

ASTM Lead Solder Standards

ASTM B579 is the standard for electro-deposited tin-lead solder. ASTM B32-08 is the specification for solder metal. ASTM B32 replaced General Motors North America GMNA standard GM6023.

ASTM E46 is the ASTM approved test for determining the chemical composition of lead and tin solder.

ASTM D269 is the test for analyzing the matter in solder rosin. ASTM D509 is the method of sampling the rosin used in soldering fluxes.

SAE Lead Solder Standards

SAE AMS4751 is the standard for tin-lead alloy solder that is 36% tin and 37% lead. SAE AMS4751 is ANSI approved.

SAE AMS4755 was the standard for lead-silver solder alloy. SAE AMS4755 was adopted by the U.S. Department of Defense. It has been replaced by ASTM B32.
SAE AMS4750 is the standard for 45Sn - 55Pb tin-lead solder. This industry standard for lead solder was adopted by the DoD.

Military Solder Standards

MIL-S-46860 was the military standard for soldering with lead-based metallic ribbon. This standard was cancelled in 1995. MIL-S-12204 was the mil-spec for tin-lead alloy solder. It was cancelled in 1993.

ISO Solder Standards

ISO 9453 gives the chemical compositions of different soft solder alloys. ISO 9455 covers soft soldering fluxes. ISO 12224 is the standard for solder wire, both solid and that which has a flux core. ISO 10564 describes the sampling method for soft solders.

Origin of Lead Free Solder Standards

Lead based solder was the standard solder used in the electronics industry for decades. In the mid-1990s, environmentalists focused their attention on the lead solder used in the growing volume of electronics thrown into the trash. While lead is toxic when ingested, there was not any solid evidence that the lead solder in electronics leached lead into the soil or water.

However, a number of industrial organizations have issued standards for lead-free solders. Lead-free solder required changes in the solders used, the heating profiles used to melt the solder, the rosins and fluxes used and the assembly processes used to assemble many electronics.

New solders based on tin-copper, tin-silver and other alloys came into mainstream use, while new repair methods were devised to repair assemblies with these lead-free solders. The European Union sought to outlaw lead based solders but had to grant exceptions to military and high reliability electronics because of the lower reliability of lead-free solder.

Standards for Shifting from Lead to Lead-Free Solder

IEC PAS 62647-21 gives the IEC's guidance for shifting aerospace and defense electronics from lead solder to lead-free solder. IEC PAS 62647-23 gives the recommendations for repairing and reworking assemblies with both lead solder and lead-free solder.

SAE Lead-Free Solder Standards

SAE/TP 2010-01-1728 gives guidance on determining the reliability of nano-silver sinter joints compared to lead-free solder joints when they are used for attaching silicon devices. SAE USCAR-40 is the lead-free solder validation test plan by the SAE.

GEIA Lead Free Solder Standards

GEIA-STD-0005-1 is the performance standard for aerospace electronics with lead free solder. GEIA-STD-0005-1 has been ANSI approved, and it was last revised in 2012.

IEC Lead Free Solder Standards

IEC TR 60068-3-12 describes methods to evaluate lead-free solder reflow temperature profiles, determining the effectiveness of different temperature profiles to reflow solder so that parts can be removed without damaging the board or surrounding components.

IPC Standards for Lead Free Solder

IPC/JEDEC J-STD-609 is the standard for marking lead and lead-free printed circuit cards and components. IPC SPVC-WP-006 outlines the round robin method of testing and analyzing silver, tin and copper lead-free solders.

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