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Datasheet missing dimensions

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DerStrom8

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Hi all,

I am preparing to start work on designing a board that uses a component in a PowerFLAT 5x6 package (the component is a power Schottky rectifier, part STPS30M100DJF from STMicroelectronics). The datasheet is here:

http://www.st.com/web/en/resource/technical/document/datasheet/CD00255467.pdf

Altium Designer (the software I am using to design the board) does not have a land pattern for the PowerFLAT 5x6 package so I am having to create it from scratch. However, looking at the footprint in the datasheet I am still missing a few critical dimensions. I contacted STMicroelectronics but have not received a response. I'm wondering if anyone has the information shown in red in the below image?

Dimension query.png

Thanks,
Matt
 

tunedwolf

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Interestingly, those dimensions also seem to be missing from the mechanical data section of every datasheet for their other devices using the same package that I have looked at :)
 

DerStrom8

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Interestingly, those dimensions also seem to be missing from the mechanical data section of every datasheet for their other devices using the same package that I have looked at :)
I noticed the same thing. I ended up cross-referencing some datasheets (I found this one which looked much closer to what I had, meaning the measurements were scaled more accurately: Datasheet) and had to guess a couple of bits, but here's what I came up with:

upload_2015-2-27_9-48-37.png


I'm thinking that should be accurate enough. The parts that I am given dimensions for are accurate down to a micrometer. I will also have one of my coworkers check the work before I start putting it on actual boards.

Thanks,
Matt
 

DerStrom8

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ronsimpson

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Where on earth did you find that??
I did a search for "PowerFLAT 5x6" and found:
1)Nothing just like you.
2)You looking for information on another forum.
3)Other companies data sheets.
4)Then I looked for other parts from ST in the same package. (dual fets, fet+diode)
 

DerStrom8

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I dug through about a dozen (maybe more) other components in the PowerFLAT 5x6 package from ST and kept getting practically identical diagrams. Anyway, thanks very much Ron, that helped a LOT! :D
 

DerStrom8

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Just thought I'd post a follow-up, the 3-D model fits it beautifully!

upload_2015-2-27_12-19-11.png


I would be concerned about the pad lengths (normally I'd want them to extend out from the pins a bit further) but since we really only do reflow soldering that should be enough. I might extend it by half a millimeter or so, but I'll wait and see what the general consensus around the office is.

Thanks again,
Matt
 

DerStrom8

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Hi all, just a quick update:

I heard back from STMicroelectronics and they have graciously provided me with a much more detailed land pattern. I thought I would post it here in case someone might get some use out of it in the future. Here it is:

land pattern.png

Regards,
Matt
 

tunedwolf

Well-Known Member
Like you Matt, I must have dug through a couple of dozen different datasheets only to be greeted with the same mechanical drawings, and not just from ST, but Rohm also. I guess the one Ron found must have escaped out the back door. It is good to see ST step up and update their information, perhaps they will roll it out on their datasheets now that it has come to their attention. I like the 3D model, fits very well indeed :)
 

Inquisitive

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I have to ask. What is the unit of measurement on the drawing?
 

Inquisitive

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I did not open the original drawing again. Thanks, Ron
 

atferrari

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How bigger than the minium could you make one of these pads in a design like this? Intrigued.
 

DerStrom8

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I have to ask. What is the unit of measurement on the drawing?
Sorry Inq. Measurements are in millimeters.

How bigger than the minium could you make one of these pads in a design like this? Intrigued.
That all depends on your application, type of soldering (wave, reflow, hand), the component itself, and the density of your board. The main thing is to avoid solder bridges between pads. You can often get away with a 10% deviation on either side of the nominal value, but again it greatly depends on what exactly you are doing. For pads, I generally look at the datasheet to find the max width of each pin on the device and give it an extra 10% on each side for the pad. However, IPC has standards for this and I often use the IPC Footprint Expert tool to calculate the pad sizes automatically. Unfortunately IPC doesn't have standards for the PowerFLAT packages (they're not very common at this point) so I had to look at the land pattern in the datasheet instead. Many datasheets show the dimensions of the component AND of the recommended land pattern, which is very useful and saves me a lot of time. I just need to check that if it is a common package, it complies with the IPC standards.

Regards,
Matt
 
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