SMT007 Magazine

SMT-Mar2014

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18 SMT Magazine • March 2014 by Jennifer Nguyen, ranilo aranda, David Geiger, and murad kurwa FlexTroniCS inTernaTional SummarY: many alternative low/no silver solder pastes are available today. this article will present the performance and process capability of various low/no silver alloy solder pastes, along with a variety of benefits and concerns. abstract Sn3.0Ag0.5Cu (SAC305) is the most popular near-eutectic lead-free alloy used in the manu- facturing processes. Over the last several years, the price of silver has dramatically increased, driving a desire for lower-silver alloy alterna- tives. As a result, there is a significant increase in the number of alternative low/no silver lead-free solder alloys available in the industry recently. In this paper, we'll present the performance and process capability of various low/no silver alloy solder pastes. Data from printability, wetting test, slump test, solder ball test, voiding, etc., will be discussed and compared with the con- trol SAC305 solder paste. Benefits and concerns of using low/no silver alloy solder paste materi- als will also be addressed. Introduction Sn3.0Ag0.5 solder paste is currently the common alloy for lead-free solder paste in the PCB assembly industry. However, the price of silver has kept increasing over the last several years. The silver price chart within the last five years is shown in Figure 1. This drives the desire for alternative low/no silver alloy materials and leads to the development of many alternative alloys. Today, many alternative low/no silver alloy solder pastes are available in the market. There are publications on the alternative lead- free alloys 1–3 . However, most of the studies fo- cus on the alternative alloys of the BGA solder balls and their reliability. There is very limited published information on the performance of Feasibility of Low/No Silver Alloy Solder Paste Materials feaTure

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