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 Post subject: SMD 0805 Resistor pad size
PostPosted: 08 Nov 2016, 15:10 
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Joined: 03 Nov 2016, 05:30
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Sorry if this have been brought up before, but i can't find any replies answering this.

I'm a bit confused on what pad size to use for my 0805 resistors. Vishay/Yageo/Panasonic all have different sized measures in their datasheets, and i dont want to be forced to use only one brand.
The included footprint in DipTrace probably works fine, and it covers all brands, I'm just worried it's too big if i ever want my design manufactured.

Any insight on this? Am i just being silly?


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 Post subject: Re: SMD 0805 Resistor pad size
PostPosted: 08 Nov 2016, 15:55 
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Joined: 20 Jun 2015, 14:39
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Here are some land pattern recommendations for reflow soldering of various SMD resistor sizes (scroll down some after loading) - http://www.resistorguide.com/resistor-sizes-and-packages/
Here is a Tom Hausherr blog that explains the "ABCs" (Maximum, Nominal, Least) of pad sizes - https://blogs.mentor.com/tom-hausherr/blog/2011/01/28/pcb-design-perfection-starts-in-the-cad-library-part-12

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 Post subject: Re: SMD 0805 Resistor pad size
PostPosted: 08 Nov 2016, 16:46 
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Thanks! Those measures are very close to the Yageo ones, which is what I've been using so far. Untested however.

Will add the numbers from the "ABC's" and go with that i suppose then. Hope the gap between pads (1.2mm) will fit other brands too, even though their datasheets recommend about 0.6mm.


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 Post subject: Re: SMD 0805 Resistor pad size
PostPosted: 08 Nov 2016, 17:10 
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The illustration below shows the difference between the "Nominal" footprint (linked to above), the standard DipTrace "RES_0805" footprint and a couple of Vishay recommendations found here - http://www.vishay.com/docs/28745/soldpads.pdf...


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 Post subject: Re: SMD 0805 Resistor pad size
PostPosted: 08 Nov 2016, 18:10 
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Joined: 22 Aug 2011, 05:29
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In general Diptrace tries to stick to IPC-SM-782A standard regarding pad sizing, but in the end it is up to you to determine how dense you want your layouts - that mentor blog link gives a good insight.
I know a guy who makes smallest possible footprints and gets away with it because he runs a SMT fab house.

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 Post subject: Re: SMD 0805 Resistor pad size
PostPosted: 09 Nov 2016, 06:04 
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Joined: 03 Nov 2016, 05:30
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Thanks everyone for chipping in, i really appreciate it!

I got inspired by the footprints above and made my own out of the datasheet's for the parts i might use. Both the patterns and components are based on these sheets, just to illustrate where it all lands.
My own version using the Panasonic resistor is the bottom one if it isnt obvious. :)


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