Lead (Pb) Free Program Status
Matte Tin is our standard terminal finish. Devices with Lead Free terminal plating have the same basic part numbers with the suffix #PBF for #TRPBF on the container labels. A summary of the Matte Tin reliability data is presented in Attachment 1. A summary of the board level surface mount evaluation results in presented in Attachment 2 (6.57MB).
Some of our packages, for example the TO-220, TO-247, SOT-223 and DD-Pak packages, are currently assembled with a soft die attach material that contains Pb (lead). These packages are exempt from Article 4 of the European Union Directive 2002/95/EC, “Restriction of the use of certain Hazardous Substances (RoHS)”. These packages use high melting point solders (>85% LEAD) to attach the die to the die paddle, and are therefore exempt from the restrictions and controls of WEEE and RoHS. For these packages, a lead-free die attach material is being evaluated, but there are no plans to change this die attach in the near future.
In anticipation of the lead-free requirements of our customers, Linear Technology Corporation began evaluating lead-free plating in 1997. A lead-free nickel-palladium (NiPd) terminal plating was qualified in June 1998. However, due to the cost volatility of this alternative plating finish coupled with concerns related to possible interruptions in the supply of raw palladium, Linear Technology decided to evaluate other alternatives.
Several alternative lead-free plating finishes were evaluated. Linear Technology settled on qualifying a matte tin plate terminal finish. Linear Technology had previously used a matte tin terminal finish on surface mount SOIC packages between the years 1983 – 1988, with excellent quality and reliability performance in the field. In the 3rd quarter of 2001, Linear Technology successfully qualified matte tin terminal finish and started to offer the product to customers in the 4th quarter of 2001 under Special Flows. In addition to in-house qualification testing, Linear Technology has worked closely with end customers and a major CEM (Contract Electronic Manufacture) on the matte-tin terminal finish with regards to ensuring acceptable and reliable re-flow soldering at the board level.
Current lead-free solder paste alternatives, which have a 25oC to 50oC higher melting temperature than tin-lead solder, push the performance limit of the systems used in printed circuit board assembly. In addition, the 260oC peak re-flow temperature used on lead-free alternatives will adversely impact the moisture performance of our packages. To date, moisture sensitivity testing conducted at a peak re-flow temperature of 260oC has confirmed this drop in moisture performance, but results to date indicate that our matte-tin plate packages are still reliable after exposure to these more stringent re-flow conditions.
Should you need additional information on our Lead-Free Program, please contact the following:
(408) 432-1900 ext. 2427