ssnyder
Newbie level 2
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
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
