Hi All,
I'm trying to make an effort to clean up my companies footprint libraries to get something that looks like IPC compliant footprints using JEDEC package drawings. The JEDEC drawings use a lot of symbols I'm not familiar with and I must admit have probably encountered before but ignored.
Attached is the JEDEC drawing for a 8-SOIC 1.27mm pitch, 3.9mm body width. Here are my many questions.
* In the table of dimensions on page 3, what does BSC mean?
* The BSC dimensions seem to have their tolerances specified with a box with a symbol of a half circle, then 3 letters referring to another table, then another capitol letter. What does this half circle symbol mean? What does the capitol letter refer to, another dimension?
* Some lines have a larger arrow coming off them pointing to another capitol letter. For instance dimension E, the lead span, has a large capitol D above it. D is the body length, what does this have to do with dimension E?
* In the boxes where 3 letters are used to specify a tolerance, there are other symbols. One is two parallel lines, for instance on the side view pointing to the top of the package. Another is a graticule, like near dimension b the pin width, which actually has a min and max specified with it's dimension. What do these symbols mean?
Looking at all these questions, it's amazing my footprints in the past fit the parts! I appreciate any help anyone can provide, I've had trouble googling for this stuff.
Cheers,
Steve