Solderability of Aavid Thermalloy Standard Catalog Products with
RoHS Compliant Plating
Background
Aavid Thermalloy is in the process of converting all standard heat sink products to make them
RoHS compliant. Although two-thirds of our most popular standard products have always been
compliant, heat sinks that have solderable mounting features such as tabs or pins have
traditionally been plated with tin-lead to maintain solderability until use. Due to the RoHS
limitations on lead content in electrical and electric products, we are releasing new versions of our
products that specify lead free solderable platings. Changing the plating requires testing to insure
that solderability shelf life of the mounting features is maintained relative to the non-compliant
plating and that the new plating is both forward and backward compatible with both tin/lead and
lead-free solders.
Approach
Based on reviews of research and testing performed by leading electronic industry corporations,
Aavid Thermalloy has selected 100% matte tin with nickel underplating as the standard
specification for lead free solderable components. The Aavid Thermalloy specification calls for 75
to 150 micro inches (1.8 to 3.8 microns) nickel underplating followed by 160 to 350 micro inches
(4 to 8.9 microns) 100% matte tin. 100% matte tin was chosen in part for its compatibility with
both tin-lead and lead free (tin/silver/copper) solders.
Test Method/Observations
Solderability testing of the compliant plating has been conducted in Aavid Thermalloy’s thermal
lab to IPC/EIA/JEDEC J-STD-002 (category 1, dip -and-look) for both eutectic tin-lead (63/37) and
tin/silver/copper (96.5/3/0.5) solder. To make the testing more representative of current soldering
practices, a mild no-clean liquid flux (Kester 959) was used instead of the rosin flux specified in J-
STD-002. All samples tested, including the latest at approximately 11.5 months after plating,
pass the visual accept/reject criteria of J-STD-002. See photos below.
Bare test pin Test pin dipped in Test pin dipped in
Sn/Pb 63/37 Sn/Ag/Cu (96.5/3/0.5)
Conclusions
After nearly one year of storage, Aavid Thermalloy standard parts with RoHS-compliant plating
continue to show acceptable solderability when tested with tin/lead (backward compatible) and
tin/silver/copper (forward compatible) solders. As always, Aavid recommends that our customers
test for acceptability in their process.
Reference
Elmgren, et al, “Pure Tin-The Finish of Choice for Connectors”, Proceedings of IPC/JEDEC
Conference, Frankfort, Germany, Oct., 2003.
Rev 8/04/05