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Is there a to-scale image available somewhere that shows SOT23, SOT323, SOT523, etc. packages used typically for discrete transistors or diodes, so that someone without access to a PCB layout program could compare them?

All I could find is https://www.centralsemi.com/PDFs/literature/Diodes_SF_English_PDF_Version.pdf which is helpful for comparing the larger packages (D2PAK, DPAK, etc.) but not the smaller ones.

(And https://www.mccsemi.com/pdf/SMDDimensionSelectionGuide.pdf where the displayed images are not accurate in relative size)

For example, here is one from ON Semi covering 6-pin packages

enter image description here

Jason S
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  • Maybe here: https://electronics.stackexchange.com/questions/334128/how-do-i-identify-smd-components-or-how-do-i-identify-any-component/334129#334129 – Voltage Spike Mar 12 '21 at 15:53
  • what do you mean with "to scale"? A digital photo is never "to scale", it's always as much to scale as you scale it; physical size is not a property of digital images. Someone comparing footprints with design tools wants a *dimensional drawing*, so the second link is actually what you're looking for. – Marcus Müller Mar 12 '21 at 15:55
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    If you have CAD models of these packages, e.g. in Inventor, as well as a functional printer that doesn't have print scale issues, printing a 1:1 scale drawing of top/side/front views is a perfectly well-supported functionality. On that note, if you are OK with just the PCB footprint layers (pads, maybe mask + silk), you can do the same thing but print the PDF plot of a PCB with the relevant footprints. – nanofarad Mar 12 '21 at 15:56
  • No, I do not want a dimensional drawing, that is not enough. I want a drawing where each package has the same scale, so if one part X is twice as big as another part Y, then X shows up in the image twice as big as Y. The MCC Semi PDF does not have that property. – Jason S Mar 12 '21 at 16:08
  • @nanofarad I have no access to CAD software; I work with people who do but they are all busy, and I'm just looking for a reference image that shows relative package sizes. – Jason S Mar 12 '21 at 16:09
  • @MarcusMüller to scale just means that the drawing and the real objects in that drawing have dimensions related by a single constant of proportionality. – Jason S Mar 12 '21 at 16:12
  • @VoltageSpike no -- that NXP graphic does not maintain the same scale ratio across all packages (see for example SOT23 and Power-SO8 -- a SOT23's dimensions are smaller but in the image it is larger) – Jason S Mar 12 '21 at 16:15
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    @JasonS Install KiCAD, it's free and easy. Otherwise, something like [this](https://www.digikey.com/en/products/detail/digi-key-electronics/PCB-RULER-12INCH/5767550) is very handy to have; it's a ruler with a bunch of common transistor/diode/passive/IC packages on it as well as a bunch of other things that are handy for making circuit boards. – Hearth Mar 12 '21 at 16:57

2 Answers2

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When in doubt, make one.

enter image description here

Using KiCad to place the desired components and then plotting the fab layer (with pad sketch) to produce the required PDF, which should print 1:1

https://smallpdf.com/shared#st=36d0795c-1b5a-4e5b-9dd6-5fab619e0258&fn=-F_Fab.pdf&ct=1615566497945&tl=share-document&rf=link

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There aren't images with all smt packages just some of them, here are a few examples.

enter image description here Source: https://passive-components.eu/good-things-come-in-small-packages-a-capacitor-technology-update/

enter image description here Source: https://upload.wikimedia.org/wikipedia/commons/3/34/SMT_sizes%2C_based_on_original_by_Zureks.svg

Voltage Spike
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  • thanks, that's along the lines I'm looking for, but particularly for small discrete diodes and transistors. (i've clarified in the question) – Jason S Mar 12 '21 at 16:28