how large to make surface mount pad?

[Michael Noone]

Hi - I'm making a board with a slightly odd sized part. In it's datasheet
there is no reccomendation for pad size - though they do give the size of
the contact. (datasheet here:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/vapubfiles/F3102T520/
$file/F3102T520.pdf)

The part is a tantalum in a kemet B case size. The contacts are 2.2x0.8mm.
How much bigger should I make the pads? Thanks!

-M. Noone

 

[PeteS]

Take this link

http://www.avxcorp.com/docs/Catalogs/techsum.pdf

Towards the end of the app note, you'll find the EIA recommended pad
sizes for each case size

If for some reason that doesn't come up, take the links in this order

www.avxcorp.com

Browse by products
Capacitors
Tantalum
TAJ series
In the related information area, you'll see a link for 'technical
summary and application guidelines'. That should take you to the PDF.

Cheers

PeteS

 

[legg]

Hi - I'm making a board with a slightly odd sized part. In it's datasheet
there is no reccomendation for pad size - though they do give the size of
the contact. (datasheet here:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/vapubfiles/F3102T520/
$file/F3102T520.pdf)

The part is a tantalum in a kemet B case size. The contacts are 2.2x0.8mm.
How much bigger should I make the pads? Thanks!

Check mfrs data, or google for 'IPC Calculator'. The latter references

IPC-SM-782A - Surface Mount Design & Land Pattern Standard

The standard is drawn from typical practice, it did not initially
define it.

RL

 

[qrk]

Hi - I'm making a board with a slightly odd sized part. In it's datasheet
there is no reccomendation for pad size - though they do give the size of
the contact. (datasheet here:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/vapubfiles/F3102T520/
$file/F3102T520.pdf)

The part is a tantalum in a kemet B case size. The contacts are 2.2x0.8mm.
How much bigger should I make the pads? Thanks!

-M. Noone

The "B" case size can be matched to a standard EIA case size. The data
sheet shows the EIA case size as 3528. This has been a standard case
size for SMT tantalums for the past 15+ years. Search for a 3528
footprint on the web. IPC-SM-782A is a good starting place. I like
using the recommendations that AVX gives over IPC.