EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: danbr on April 28, 2015, 02:01:12 pm
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Hey,
I'm trying to build up a part in eagle cad using the LPS25H pressure sensor.
The problem I'm having is that the datasheet for the part has a HORRIBLE diagram for trying to figure out the LGA solder pad size and placement. Its a HCLGA-10L package.
Page 43:
http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/DM00066332.pdf (http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/DM00066332.pdf)
Is there something I'm missing here? Or does the diagram really suck. This is pretty much the only thing keeping me from going to the pcb printer.
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its not too bad, annoying not to have the numbers right there on the measurements though.
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The dimensions for placing the pads isn't so bad.
But I'm I missing something, no where do I see the length and width of the pad listed. I know my geometry, and assuming that image is to scale I could figure it out, but that seems like a pain for what should be a simple listed dimension.
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b: 0.25 0.35
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What the hell?!
B = b?
Why couldnt they just use matching notataion |O
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Yep... have fun with that...
You'd think it was drawn in China......maybe it was..
Seems like they're missing a full page: detail "B" is missing; notes 3, 4 and 6 are indicated but missing (no idea about the remaining notes); section A-A is missing; and dimensions b and L are missing from the drawing (likely belonging to detail "B").
b and L are IPC standard symbols for width and length of the pad, in any case, so that should be what you need. Mind that pads 1, 2, 6 and 7 are rotated.
IPC rules are usually pad = pad (nominal zero side fillet), with NSMD (non soldermask defined) preferred.
The product page, http://www.st.com/web/en/catalog/sense_power/FM89/SC1316/PF255230?s_searchtype=keyword# (http://www.st.com/web/en/catalog/sense_power/FM89/SC1316/PF255230?s_searchtype=keyword#) suggests this (Design Resources / TN1198), but sadly doesn't provide the missing drawing sheet!
You can email them about it. You might get a response, which is nice; but in my limited experience with ST, you won't get action.
Tim
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I contacted ST support and they did get back to me!
They suggested that I use the LPS25HB, as both the documentation is better (for dimensional drawings) as well as its a waterproof sensor! The electronics are the same I was told, so I will just go with this new part.
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I'll never understand why component manufacturers don't utilize reference dimensions...The rest of the world has learned to use them.