I'm creating a PCB design using LPC4088 in the TFBGA208 (SOT950-1) package. There is no recommended PCB footprint on the datasheet and there is conflicting information between NXP documents.
This document states that the PCB pads should be 0.475mm diameter, and the solder paste should be 0.425mm diameter:
https://www.nxp.com/docs/en/package-information/SOT950-1.pdf
This document states that the PCB pads and solder paste should both be 0.35mm diameter:
https://www.nxp.com/docs/en/application-note/AN10778.pdf
Which is correct?
Hi Jeremy,
Thanks for your reply. If I use the pad sizes in the document you suggest, what via sizes and track and gap sizes should I use, as the ones in the application note (https://www.nxp.com/docs/en/application-note/AN10778.pdf) are not valid for those pad sizes?
Thanks
Tim
TIC
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Hi Jeremy,
It is not possible to follow both SOT950-1 and AN10778. This is the reason for my original question. If I use the recommended pad size from https://www.nxp.com/docs/en/package-information/SOT950-1.pdf and the via and track size from AN10778, the via-to-pad spacing will be 0.0857mm, which less than the clearance specified in both documents, and is too small for most PCB manufacturers. So should I be using a smaller pad than specified in SOT950-1, or a smaller via than specified in AN10778?
Tim
Hi Tim Barry,
1) So should I be using a smaller pad than specified in SOT950-1, or a smaller via than specified in AN10778?
You can consider to use a smaller pad than specified in SOT950-1.
Hope it helps.
Have a great day,
TIC
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