IPC have updated IPC/JEDEC J-STD-609 - May 2007 on marking and labelling of electronics and have included new coding for the second generation of lead-free solders.

A key issue in the implementation of lead-free soldering was the need for a marking standard amidst the significant complexities to inventory control amidst a sudden proliferation of new materials. It was especially important that lead-free products should be clearly distinguishable from leaded products, not only for compliance but also to avoid compatibility issues in assembly. It was further necessary to identify which lead-free solders and finishes had been used to avoid such problems in rework.

J-STD-609 was introduced in 2007 to resolve these issues. It contains a set of e-codes for different lead-free solders, b-codes for lead-free finishes and additional codes for base materials etc. Guidelines were laid out for exactly what sequence the codes should be used in together with where and how the labels should be displayed on boards, components and packaging.

The main amendment in relation to solders is the addition on a new e-code 'e8' for second generation low-silver (or 'alternative') alloys now appearing on the market.  This specifies SAC alloys with 1.5% Ag or less, with or without additions. It excludes Zn and Bi containing alloys which are to be separately identified under e5 and e6 respectively.

The new standard is IPC/JEDEC J-STD-609A-2010 and is available from IPC on the reference link below.