Christopher Associates' Jasbir Bath to Present on Low Silver Pb-Free Alloy Solder at SMTAI
September 2011 - Christopher Associates/Koki Solder announce that Jasbir Bath, Consulting Engineer, co-authored the paper titled “An Investigation into Low Silver Lead-Free Alloy Solder Paste for Electronics Manufacturing Applications,” to be presented at the upcoming SMTA International Conference & Exhibition, scheduled to take place October 16-20, 2011 at the Fort Worth Convention Center in Fort Worth, TX. The presentation will be held during Session MFX4, titled “Alternate Lead-Free Alloys: Materials and Processes,” which will take place Wednesday, October 19, 2011 from 10:30 a.m.-12p.m. in Room 202D.
The electronics industry has widely adopted Sn3Ag0.5Cu solder alloys for lead-free reflow soldering applications. One of the challenges with this alloy is the use of the three percent silver that has caused rapid price increases in solder alloys because of the limited global availability of silver metal.
Low silver containing alloys have been developed to address the cost issue, but they have been mainly found to have reduced thermal cycling reliability performance compared with Sn3Ag0.5Cu. Development was performed on a new lead-free solder alloy (Sn0.1Ag0.7Cu0.03Co) as a potential replacement for Sn3Ag0.5Cu. Bulk alloy mechanical testing was performed for Sn0.1Ag0.7Cu0.03Co, Sn3Ag0.5Cu, Sn0.3Ag0.7Cu and SnCuNi solder alloys. Solder joint thermal cycling tests showed equivalent or better reliability for the Sn0.1Ag0.7Cu0.03Co alloy compared with Sn3Ag0.5Cu. Additionally, copper erosion tests were performed with the low silver cobalt containing alloy showing reduced copper erosion versus Sn3Ag0.5Cu.
Reflow profile development also was performed with the 227°C melting point Sn0.1Ag0.7Cu0.03Co alloy to understand peak temperature and time above liquidus guidelines during board assembly. The presentation will report on the results of these tests.
Jasbir is a Consulting Engineer for Christopher Associates/ Koki Solder in the Americas. He was the Corporate Lead Engineer with Solectron Corporation and Flextronics International for ten years with a role involving tin-lead and lead-free solder process development.