SMT007 Magazine

SMT007-Oct2020

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10 SMT007 MAGAZINE I OCTOBER 2020 Requirements for Electronic-Grade Solder Alloys and Fluxed and Non-Fluxed Solid Solders for Electronic Soldering Applications This writing is a follow-up to the Part 1 col- umn published in January 2020 that addressed the questions that had been raised regard- ing the joint industry standard. The specific questions were related to the lead-free alloy designations (a naming system) adopted in IPC J-STD-006 and the alloy designations expressed in Table A-1 of the standard, enti- tled "Composition and Temperature Charac- teristics of Lead-Free Solder Alloys." At the time of the revision, Table 1-A was essentially intended to be dedicated to new and existing lead-free alloys. As the mid-year IPC Standard Committees meeting (SummerCom) was canceled as a result of the COVID-19 pandemic, I am using this space to address the questions. I will pri- marily summarize relevant background infor- mation, the options for plausible naming sys- tems, and the logic behind the decision to adopt the current naming system. Background of Alloy Designation or Naming System The revision J-STD-006B, published in Janu- ary 2006, was the first industry-wide effort to include lead-free solder alloys in the J-STD-006 document. I was tasked to draft many parts of this revision, including Table A-1, by consider- ing all available test data, opinions, comments, and historical and current information, as well as scientific principles and judgment. We relied on several fundamental under- standings and definitions: 1. A solder alloy is a mixture of elements in which the primary constituent is a metal. 2. The primary metal in an alloy is regarded as the base metal or the matrix. Joint Industry Standard IPC J-STD-006: Electronic Solder Alloys, Part 2 SMT Prospects & Perspectives by Dr. Jennie S. Hwang, CEO, H-TECHNOLOGIES GROUP

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