My guess is that the TSOP packages do have Alloy 42 lead Steve, My guess is that the TSOP packages do have Alloy 42 leads and that you may be seeing a failure that has gotten the name "Double Reflow" I hate that name almost as much as I hate the name "Black pad". What do the solder fillets look like on your TSOP packages? If they look good but your testing is indicating an intermittent and you can pass test by pushing down on a TSOP lead I think you most likely have a brittle interface solder joint fracture. It will look like a perfect surface mount solder joint with nice feathered solder fillets like it is wet well to the PCB pad, and it probably was when it was formed. However, then the temperature is elevated and there is any mechanical stress the solder joint can facture at the IMC bulk solder interface. You won't be able to see the fracture unless you view it at a low angle under high magnification. The "Double Reflow" name was coined by IBM Austin back in 1979 presentation at NEPCON. They called it "Double Reflow" because their surface mount solder joints look great after surface mount reflow soldering but failed (fractured) after the boards were wave soldered (i.e., failed at the second reflow). I've attached their NEPCON paper as well as one we did describing a solder joint fracture we had using QFPs with Alloy 42 leads. We also saw similar failures on another product on corner leads after the initial surface mount reflow. Those failures occurred during the first reflow and had nothing to do with double reflow. The solder joint fractures occurred on corner leads during the surface mount reflow cooling process. Regards, George George M. Wenger Senior Principle FMA / Reliability Engineer Wireless network Solutions Andrew Corporation, 40 Technology Drive, Warren, NJ 07059 (908) 546-4531 [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory Sent: Thursday, May 24, 2007 8:45 AM To: [log in to unmask] Subject: [TN] Silver Embrittlement? Mornin' all! I know this subject has been talked about before, but my memory is getting rusty. I was wondering if it was possible to get solder joint embrittlement on a board that has immersion silver finish and components that have a flash gold finish? As you might have guessed, it's those pesky Samtec SMT connectors... We're experiencing another issue on that board as well. We're seeing solder joint problems with some TSOP-66 DDR SDRAM that are on the topside of the board. They're arranged close around two XILINX 1152-ball BGA's that get very hot when the assembly is under power. Both BGA's have large finned heatsinks mounted to the top of them. The BGA's get so hot that if you power the board up without the heatsinks, and touch one of the BGA's, you will burn your finger. There have been some cases that during testing the board will fail and the failure points to one of the SDRAM TSOP's. If you take something like the end of a wooden Q-Tip and press on a suspect lead, the board passes test. The solder joint looks fine upon initial inspection, but there's obviously an open connection. I remember at one time TSOP leadframe material used to be made of Alloy-42, is that still the case? These are parts from Micron (MT46V16M16TG-6T), and I haven't yet found what the leadframes are made of. I'm wondering if the stiffness of the leads may be contributing to the solder joint failures that we're seeing. My theory is that because the BGA's run so hot, they heat the PCB and cause board to expand in the area around them (where the SDRAM are mounted). If the leads on the SDRAM are stiff and non-compliant, the solder joints might fracture. Crazy theory I know, but I'm trying to figure what's going on with these boards... 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