Alloy 42 is simliar to Kovar and is used as a "controlled expansion" alloy, typically where a low CTE metal is needed (e.g. lead sealing). The material is 42% Ni with the balance iron and has a CTE of ~ 5.2 ppm/C. Solderability-wise alloy42, like most nickel alloys, is hard to solder if given a chance to oxidize. My guess would be either a) the lead frame was oxidized prior to application of plating and therefore the plating reflows leaving a non-solderable surface exposed and/or b) the "sides" of the leads are "punched out" and not plated (or incompletely plated) and the exposed lead material oxidized (e.g. during burn in) and is non-solderable. ______________________________ Reply Separator _________________________________ Subject: Alloy 42 Author: [log in to unmask] at esdigate Date: 4/16/96 4:28 PM We have a customer who says that a previous supplier had problems soldering some fine pitch components (15 mil) because the lead material was "Alloy 42". They had a tin/lead coating (85/15). They were also told that many component mfgrs are going to be using this material. We are not familiar with this lead material but since it is solder coated do not hink it should be a problem. Anyone have any knowledge or experience in this area? Thanks in advance for your consideration. Leo Reynolds Electronic Systems, Inc.