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SMTnet featured article

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#53071

SMTnet featured article | 4 January, 2008

Can someone explain me what the table in the featuerd article "Developing a Reliable Lead-free SMT Assembly Process" is about? I know it has something to do with MSL, but how should these values be interpreted?

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#53073

SMTnet featured article | 4 January, 2008

Here's a link to the article that Loco references in the above post: http://www.smtnet.com/library/files/upload/DevelopingaReliable.pdf

The table seems to be taking a simplistic approach. J-STD-020C, Table 4-2 lists nine catagories of MSL classification, as compared with the three listed in the table you reference.

IPC/JEDEC J-STD-020C states "Engineering studies have shown that thin, small volume SMD packages reach higher body temperatures during reflow soldering to boards that have been profiled for larger packages. Therefore, technical and/or business issues normally require thin, small volume SMD packages (reference Table 4-1, 4-2) to be classified at higher reflow temperatures." So, J-STD-020C, Table 4-2 defines higher temperature catagories for thin, low volume components than thick, higher volume components. A copy of the standard is here: http://www.jedec.org/download/search/jstd020c.pdf

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