Thursday, May 26, 2016
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Nihon Superior Intros Ultra Low Voiding Solder Paste
Lead-free solder paste.
Osaka, Japan — Nihon Superior Co. Ltd., a supplier of advanced soldering materials to the global market, is introducing a newly developed solder paste for low voiding in soldering processes and materials. Called SN100C P810 D4, the new paste is especially designed for use in vacuum reflow with nitrogen.

The high-reliability no-clean lead-free solder paste is optimized to deliver excellent reflow characteristics while reducing voiding. The vacuum reflow process reduces voiding compared to the traditional reflow process; however, the new paste further reduces voiding to less than one percent in measured void area.

In developing the new paste, the company took a new approach to the design of a solder paste that would minimize voiding in the large solder joints that provide a critical thermal path for heat dissipation from power semiconductors. While optimizing the balance of low boiling and high boiling solvents, the company's scientists looked specifically at the effect of the flux medium on the surface tension of the solder. High surface tension inhibits the escape of flux volatiles by limiting the size of the bubble formed by a given amount of volatile material.

Formulating the flux system to reduce surface tension, the bubble size is increased and bigger bubbles are more likely to escape than small ones even with the benefit of vacuum reflow.

The likelihood of bubble entrapment is further reduced by the eutectic solidification of the SN100C alloy, now in its 13th year of use in high volume lead-free assembly. In the two-stage non-eutectic solidification of SAC alloys the primary tin dendrites form a network that can block the escape of gas bubbles. SN100C P810 D4 generally can be reflowed with a profile similar to that commonly used with SAC305 and SAC405 with 245°C peak. In the extended time above liquidus (TAL) that some joints in complex high thermal mass assemblies sometimes experience during reflow, the proven very low tendency of the SN100C alloy to dissolve copper from the pad provides an additional reliability benefit.

Contact: Nihon Superior Co. Ltd., NS Bldg., 1-16-15 Esaka-Cho, Suita City, Osaka, 564-0063 Japan 81-(0)6-6380-1121 fax: 81-(0)6-6380-1262 Web:
http://www.nihonsuperior.co.jp


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