topic TFBGA208 footprint in LPC Microcontrollers

TFBGA208 footprint

timbarry — Thu, 08 Feb 2018 16:28:49 GMT

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?

Re: TFBGA208 footprint

jeremyzhou — Sun, 11 Feb 2018 02:03:30 GMT

Hi Tim Barry,

Thank you for your interest in NXP Semiconductor products and 

the opportunity to serve you.

Please referring to the this document.

https://www.nxp.com/docs/en/package-information/SOT950-1.pdf

Hope this is clear.

Have a great day,

TIC

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Re: TFBGA208 footprint

timbarry — Mon, 12 Feb 2018 08:00:15 GMT

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

Re: TFBGA208 footprint

jeremyzhou — Tue, 13 Feb 2018 01:47:06 GMT

Hi Tim Barry,

Thanks for your reply.

It's appropriate to refer to the guide of 1.0 mm and 0.8 mm pitch BGA in the AN10778.

Have a great day,

TIC

Re: TFBGA208 footprint

timbarry — Fri, 16 Feb 2018 14:09:53 GMT

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

Re: TFBGA208 footprint

jeremyzhou — Wed, 20 Jun 2018 10:51:18 GMT

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