We were just asked the SN62 question yesterday by a subcomponent supplier! So, more than just you questioning the need. Here's what we said: The 2% silver was added to reduce silver leaching from thick film conductor pads. Since hybrid manufacturing was our start and remains half our business, it makes sense to have only one type of solder paste in the building. Avoids confusion, even though there is a cost factor. There are some other benefits as well. Overall advantages: 1) Reduce silver leaching from thickfilm conductor pads. 2) Higher shear strength. 3) Higher creep resistance. 4) Better cosmetic appearance (shiny joint, especially if gold on solder pad) 5) Process considers SN62 the same as SN63. Disadvantages: 1) Higher cost. Glenn Reference: "Soldering in Electronics," R.J. Klein Wassink -----Original Message----- From: Alan Kreplick [mailto:[log in to unmask]] Sent: Wednesday, October 03, 2001 12:27 PM To: [log in to unmask] Subject: [TN] Sn62 vs. Sn63 Hello Technet: We're currently using a water-soluble Sn62 solder paste, in which the formulation is five plus years old. We're beginning a solder paste evaluation using the current solder paste, a newer formulation from that manufacturer plus a half dozen other solder pastes from other leading paste manufacturers. Many of the paste manufacturers have asked why we're using Sn62, and we're now asking ourselves the same question, "Why not make the switch to Sn63 during the paste evaluation?". So, two questions: What are the major Pro's & Con's of Sn62 vs. Sn63 (mechanical, electrical, processing, etc.)? Anybody willing to share their solder paste evaluation/qualification (techniques, results, lessons learned, etc.) As, always, thanks in advance for your responses. Al Kreplick Sr. Mfg. Eng. Teradyne, Inc. 500 Riverpark Drive North Reading, MA Tel: 978-370-1726 Fax: 734-661-5352