No Option For Pad Round-off In V2021 Edition? |
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sot23
New User Joined: 30 Jun 2022 Status: Offline Points: 9 |
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I must agree with what is said about the lack of place & size round off. I understand that it is not IPC compliant but it sure was handy to match grid ! Another issue I see with the lack of this functionality : different part manufacturer often describe slightly different tolerances for the same packages. With lands rounded to 0.01mm, we will end up with a lot of different footprints for the same package. One for the (let's say) Infineon Part, one for the On Semi part... For exemple : The demo SOD package in Footprint Expert has a pin width (b dimension) between 0.55mm and 0.75mm. It gives this padstack : r77_87m97_107r19 If I change the pin dimension to 0.56mm-0.74mm (0.01mm difference on both dimensions), the padstack now is : r77_86m97_106r19 I think that this will create a lot of duplicates in our footprint library because unattentive designers will not take the 2 seconds needed to check if the first padstack could acomodate the second pin size (smaller in all it's dimensions). I don't know if I am easily understandable. It is great that we can change it using the "Use mfr. recommended pattern" option though. But I know some designers that will not take the 30 seconds needed to do the change. We sold them an "automatic footprint creation software", they will want it to be fully automated :p Another slight issue I have found with the way values are rounded (using the Decimal Place Accuracy option) is in the naming of the padstacks. If we use the demo QFN (with thermal tab) with a Decimal Place Accuracy of min:2; max:2, the name given to the padstack is r73_30m93_50r7. But the padstack is actually a 0.74mmx0.30mm rectangle (not 0.73mmx0.30mm). I think this is due to the fact that, when Decimal Place Accuracy is set to min:2, max:3, the actual length of the padstacks is 0.737mm. That gives the r73_30m93_50r7 naming. But that naming isn't updated when using min:2, max:2 accuracy. I rebooted the software but the issue is still there. Anyway, thank you for that great software. It offers tremendous flexibility and the user interface is great in my opinion.
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718 |
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You can round off the pad stacks any way you want using the "Mfr. Recommended Pattern" panel in the Calculators.
Round up or down whatever you want. Also, the "Tools > Options > Console > Pad Size > 2 Places" with round all pad sizes to 0.01 mm increments. If you want 0.05 mm increments us the "Mfr. Recommended Pattern" panel. |
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daniel.lange
New User Joined: 12 Jul 2023 Status: Offline Points: 3 |
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can you explain that more?
If you want 0.05 mm increments use the "Mfr. Recommended Pattern" panel. I don't get that. In the end I would like to have a calculation where everything is roundoff to 0.05 mm Pad sizes and Positions. only so I can reuse Pad Stacks and have a small Padstacklib and all my cells follow some grids. In old Library Expert version it was easy to config and now ... I don't know. My entry. Is that the calculation now? if so, I need that in roundoff 0.05 (to do manual it wouldn't be correct) Here I did my best. Is there really no other way to calculate with roundoff 0.05 in the first place, like it did in old version? |
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718 |
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Then you should stay with the old version of V2020.03 Library Expert.
Footprint Expert follows the IPC-7351 for the mathematical model for pad stack calculation. The IPC-7351 mathematical calculation includes the Fabrication & Assembly Tolerances, the Package and Terminal Lead Tolerances, the Toe, Heel and Side solder joint goals and everything is rounded to the nearest 0.01 mm increment. If you round the pad stack dimensions up or down to 0.05 mm increments for pad size, then it's not IPC-7351 compliant. Also, if you round the pad stack dimension up or down, do you really want to round Down? Or just round everything Up? If you can answer this question then you should be able to open the Mfr. Recommended Footprint panel and manually round all values up to 0.05 increments and you will not get a Density Level suffix of L, N or M in the Footprint Name because it's your pad stack dimensions and not the IPC-7351 calculation. |
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daniel.lange
New User Joined: 12 Jul 2023 Status: Offline Points: 3 |
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You say if you round the calculated values its not compliant to IPC-7351. But the V2020.03 did round it, so that means that the old version isnt IPC-7351 compliant. But you suggest that I should use the old version. Sorry thats not logical for me.
Of course its compliant to round up padsizes and round up or down pin positions and gaps between pads. the goal is to have less padstack geometries and nice pin postiongrid for easier fanout and routing. A good librarian and a skilled layouter will like that. All our lib is in 0.05mm steps (only some big CPUs will have 0.001mm accuracy, but for them i dont need that tool) Interesting that I am not the only one who miss that feature for clean library build up. I am disappointed that the feature is gone and that you dont understand why its important. the manual input for manufacturer recommendation will not help with that topic, becasue you can type in every value But yes I will go back to the old version of the tool, thanks for that advice. thats the solution for that. |
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Tom H
Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718 |
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Many companies are still using V2020.03 Library Expert and will be for years to come.
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daniel.lange
New User Joined: 12 Jul 2023 Status: Offline Points: 3 |
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Would you please provide an official download link? my local distributor cskl only provide the last 2023 version, thanks
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Nick B
Admin Group Joined: 02 Jan 2012 Status: Offline Points: 1908 |
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I will send you an email.
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