SO vs SOIC packages - Do they differ between manufacturers? - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 21, 2021, 07:24:09 am
content: I recently ordered a Texas Instruments CD40106 in a SO14 package,thinking and assuming it is equivalent to a Nexperia SO14 package.It is not.The TI part is wider, and should have been in a SOIC14 package.Am I mistaken here,or are package names not always equivalent between manufacturers?

author: Mecanix
author_rank: Frequent Contributor
timestamp: February 21, 2021, 07:59:36 am
content: You are correct. I've spent quite a fewhoursdays populating an EDA library of so-called 'common' components last spring and one thing I've learn from doing that is; always (always) order a sample part and measure it prior doing anything to it. Occasionally way off tolerances (not often but, you know... some). The only consistency between pckg & their mfg that I've appreciated so far is the pitch :/

author: ataradov
author_rank: Super Contributor
timestamp: February 21, 2021, 08:06:04 am
content: There are narrow and wide body versions. It is not dependent on a manufacturer, they are just different packages. And more often than not there is no distinction in the name used in the datasheet. Sometimes drawing will mention the body type. Often only if both versions are available.Package naming is nuts. And unfortunately it gets progressively worse. You can't rely on the name, you just have to check the dimensions every single time.

author: exe
author_rank: Unknown
timestamp: February 21, 2021, 08:53:28 am
content: I have two techniques to minimize problems with footprints.1) I try to buy parts before ordering pcb. I print a picture of pcb in 1:1 scale and the put components to see if they fit.2) I compare dimensions of spacing of pads on pcb with what datasheet provides.In general, I try to use exact same component from my EDA database with what I buy (that's not bullet-proof, at least once I had wrong pin assignment). Alternatively, I try to download components from the manufacturers website. Mouser often provides models, check this:https://nl.mouser.com/ProductDetail/Texas-Instruments/CD40106BE/?qs=YhsVCygOPE1CyKyInx%252Bh3Q%3D%3D(in "ECAD Model" row). Not sure how accurate what they provide.

author: AndersJ
author_rank: Frequent Contributor
timestamp: February 21, 2021, 09:09:19 am
content: Quote from: ataradov on February 21, 2021, 08:06:04 amYes,I realize there are narrow and wide packages.My issue/question is whether it is correct that a Nexperia SO14 differs from a TI SO14,or if I am wrong, drawing that conclusion.

author: ataradov
author_rank: Super Contributor
timestamp: February 21, 2021, 09:12:43 am
content: SO14 is not a complete description of the package. So yes, they can be different yes still be called SO14.

author: exe
author_rank: Unknown
timestamp: February 21, 2021, 10:14:49 am
content: Quote from: AndersJ on February 21, 2021, 09:09:19 amWell, if we are talking about CD40106, then in datasheets for CD40106 from Nexperia and TI have same dimensions and pitch.My experience with SO(IC) is that they are compatible between manufacturers with some minor dimensional differences and slightly different tolerance (except for wide/narrow body, that's a bummer). They may also have slightly different recommended pads. In same rare cases SOIC can come with thermal pad.Speaking of dimensional differences, this one has slightly different size than the one from TI:https://www.allegromicro.com/-/media/files/datasheets/a8498-datasheet.ashx. But I bet 0.2mm difference won't prevent soldering, at least not soldering by hands.If you need to be absolutely certain then check the drawings in datasheets.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 21, 2021, 02:24:43 pm
content: SO14 and SOIC14 are not the distinctive names of two different packages as you seem to think. They mean the same. "IC" is just for "integrated circuit" which is obvious anyway.Either the wide or narrow type can be called SO14, or SOIC14. So neither of the names fully describe a package. These two types, wide and narrow body, are most typical, but I wouldn't be surprised to find out about yet again different type. Also thermal pads mix things up.You need additional identifier to tell you whether it's about the wide or narrow type. For this, no universal naming standard exist, depends on the chip manufacturer what they call them. Magical words like JEDEC, EIAJ, JEITA, "wide", "narrow" exist, in addition to any manufacturer-specific extra letters and so on. Read the datasheets carefully and look at the part numbers you order carefully to match them to the exact part in datasheet. Always refer to the datasheet drawings. Don't make assumptions related to "common" package types.

author: coppice
author_rank: Super Contributor
timestamp: February 21, 2021, 02:34:53 pm
content: Quote from: exe on February 21, 2021, 10:14:49 amHave you checked the exact suffix on the parts you have against their datasheets? Many commodity multi-sourced parts are made in multiple width packages, so manufacturers can grab each other's business during production runs. You need to check the suffix carefully against what is in the datasheet's dimensions page.

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 21, 2021, 03:23:29 pm
content: To me, SO and SOIC is the same thing.(SO = "small outline", SOIC = "small outline integrated circuit")There is a "wide version" that is usually called SOICW, but naming varies unfortunately. You may see SOICW14, SOICW-14, SOIC14, SOIC14-W, SO14W... A "wide" version without the W letter in the packaging name is wrong, though. Unfortunately, package names are not always very precise and you need to check datasheets. Every vendor tends to have their own convention.https://www.ti.com/lit/ds/symlink/cd40106b.pdfhttps://assets.nexperia.com/documents/data-sheet/HEF40106B.pdfTI's package body is wider indeed, but not as wide as a 'wide' SOIC package. I agree this sucks and all I can tell you again is to check datasheets when looking for equivalent parts.In TI's datasheet, you'll see that they actually have a package similar to Nexperia's one. BUT. Nexperia's "SO14" is a 3.9mm-wide body. TI actually calls "SO" in their packaging tables (for short, they have a longer internal name for packages) - part suffix 'NS' - the wider body (5mm+), and "SOIC" the 3.9mm body - part suffix 'D'.So definitely do not expect 'SO' and 'SOIC' to help. Always check datasheets. Yes this bites.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 21, 2021, 04:07:39 pm
content: I have seen with some packages a clear difference between manufacturers, e.g, SOIC-8. As a rule, I always check the package footprint in the datasheet. In some instances, manufacturers do not include the footprint, but refer to a compendium of their footprints.Of course, they are usually similar enough not to make a difference. That would be no comfort when they are different, and I didn't check.

author: Renate
author_rank: Super Contributor
timestamp: February 21, 2021, 04:17:37 pm
content: Quote from: ataradov on February 21, 2021, 08:06:04 amNot as bad as display names!Oh, yeah, a WQXIASVGA is a wide, quad, inverted, anamorphic stereoscopic VGA!

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 21, 2021, 04:19:42 pm
content: Quote from: jpanhalt on February 21, 2021, 04:07:39 pmUnfortunately, this 3.9mm vs 5mm width difference is enough to make them not footprint-compatible, unless you design a specific footprint to accomodate that (which would be OK for hand soldering but may not be ideal for automated reflow.)

author: tooki
author_rank: Super Contributor
timestamp: February 21, 2021, 04:22:40 pm
content: Quote from: AndersJ on February 21, 2021, 07:24:09 amYou know that a simple Wikipedia search would have told you that there are multiple widths of SO/SOP/SOIC packages, and that they depend on the standards body and specific standard, not manufacturer. See:https://en.wikipedia.org/wiki/Small_outline_integrated_circuitWith SMD components in general, it’s never a bad idea to verify package and pin dimensions, since they can vary, and images don’t always give any scale which could tip off about a difference.

author: tooki
author_rank: Super Contributor
timestamp: February 21, 2021, 04:36:22 pm
content: Quote from: SiliconWizard on February 21, 2021, 03:23:29 pmNo, you can’t say that “SO14” without W is “wrong”: TI’s convention (which closely follows the standards bodies) is to useSOICto refer to JEDEC standards, andSOto refer to JEITA standards. As it happens, JEITA’s narrowest is wider than JEDEC’s narrowest.Nexperia is following JEDEC but calling itSO, notSOIC. Not as faithful to the conventions of the standards bodies, but still not outright wrong.Both are perfectly clear in terms of prominently printing the body width on the datasheet.Also, note that you mixed up the part suffixes and the package drawing codes. D (SOIC) and NS (SO) are the package drawing codes, NOT the part suffixes! M is the part suffix for SOIC, NS for SO. But just to be clear for the OP, these are just TI’s codes, not any kind of industry standard. Each drawing, however, does cite the relevant industry standard.

author: exe
author_rank: Unknown
timestamp: February 21, 2021, 04:42:04 pm
content: Quote from: coppice on February 21, 2021, 02:34:53 pmNot sure I understand you, I only checked "box" dimensions for what I'd call soic-14. Fortunately, they have non-overlapping suffixes, so it's impossible to get a part in unexpected package. Both have ordering information on the very first page, which super helpful to me.Btw, LCSC provides photos of actual parts, so it's easy to do some at least some sanity check:https://lcsc.com/product-detail/4000-Series_HGSEMI-CD40106BMTR_C194331.html.

author: nctnico
author_rank: Super Contributor
timestamp: February 21, 2021, 04:50:39 pm
content: Quote from: exe on February 21, 2021, 04:42:04 pmUntil they don't. Never ever rely on pictures in catalogs or datasheets. Always use the dimensional drawing which matches the package / order code and check that against the footprint in your PCB design program. It helps to have a part database which stores the manufacturer's order code together with the symbol and the footprint. That way you have to do this thourough check only once.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 21, 2021, 05:02:56 pm
content: Yes, a distributor picture can warn you about a possible mismatch but that's the last line of defence, don't trust it alone, always check properly.Also be very careful to verify that,1) distributor datasheet pdf link really opened the right file2) datasheets relevant to multiple different part numbers, read the correct sections.Drawing / verifying correct footprints is somewhat time-consuming and feels like a daunting task first but once you make it your default process, you'll see it isn't too bad, even a single fuck-up costs more time than verifying 1000 footprints.

author: jmelson
author_rank: Super Contributor
timestamp: February 21, 2021, 05:08:16 pm
content: SO is NOT the same as SOIC. I think SO is a Japanese standard that came out about the same time as the US SOIC dimensions. SO uses the same lead pitch, but the body is wider. The SO body is about 5.3 mm wide, SOIC body is 3.8mm. The outer tips of the SO leads are 8mm, for SOIC they are 6.0Digi-Key stocks both, I've ordered the wrong size several times in the past.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 21, 2021, 05:12:45 pm
content: Basically, the process goes like this,1) You find the best part ever you want to use from a distributor parametric search. The part is ABC123. You opened the pdf, looked at the specs. Great.2) Now look carefully, the datasheet talks about ABC123XYZ56. It lists three different packages; look at all the drawings, decide which package you want. It's called a package QWE with a drawing code RTY.3) Still the same pdf open, reference to the table which lists the available part codes. Look at the column that shows this QWE or RTY package. Now you have the full part number, it's magically ABC123XYZ56GHJ.4) Still the QWE aka RTY package drawing open, create a new footprint in your PCB EDA. Draw it! If this takes too much time or requires tedious initialization ritual steps, learn another PCB EDA which does this right. To be extra sure, you can name this ABC123XYZ56GHJ, then this footprint is for this part only, preventing reuse, but at least you have a 100% correct footprint every time. Or you can name the footprint "manufacturer_x_qwe_aka_rty_package". Or you can try to find more generic patterns like calling it "soic14-narrow" but the more generic you go, the more risk you have.5) Be sure to buy ABC123XYZ56GHJ, nothing else.6) Double-check the footprint once more against the datasheet drawings.7) Safety-check against the distributor photo, or another competitor part drawing youexpectto be same. If non-match, your original footprint based on the correct datasheet is still likely the correct one, but a difference could set off alarm bells; be careful!

author: Siwastaja
author_rank: Super Contributor
timestamp: February 21, 2021, 05:13:40 pm
content: Quote from: jmelson on February 21, 2021, 05:08:16 pmThis is your definition. Someone else may also follow it but by no means is it any kind of universal standard to be trusted. Do not try to signify between the wide and narrow (JEDEC) SOIC by just using "SOIC" and "SO" respectively, confusion guaranteed.

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 21, 2021, 05:21:40 pm
content: Quote from: tooki on February 21, 2021, 04:36:22 pmI can. As I clearly said, the SOIC 5-mm body is NOT a SOIC-wide. SOIC wide bodies are 7.5mm wide (and 10mm with the pins.)Quote from: tooki on February 21, 2021, 04:36:22 pmWhatever, they are using the same abbreviations to refer to different packages. This is what is confusing to customers.Quote from: tooki on February 21, 2021, 04:36:22 pmYes, as I said, always refer to the datasheets. And as I said, TI actually has the two different widths, whereas Nexperia only offers one.The point was exactly that. Each vendor does a different thing, and you need to be aware of it.Quote from: tooki on February 21, 2021, 04:36:22 pmTI is very nice for that. Ahem. The "NS" package can be found in the suffix for the "CD40106BNSR", the "PW" package in "CD40106BPW" and "CD40106BPWR", but not for "N", "J" and "D".Same thing for most of their parts. The "package drawing" suffix can be found in some of their parts' ordering suffixes, but not all. So that you pretty much always have to consult the full "PACKAGING INFORMATION" tables.

author: exe
author_rank: Unknown
timestamp: February 21, 2021, 06:19:04 pm
content: Ideally, I'd like to have parts database integrated right into my EDA. This way there is no confusion between part number and foot-print. May be even one-click purchase. I heard major EDAs support parts datatabe, often at extra price. My EDA (diptrace) doesn't offer any integrationsI have to draw quite a few parts by myself. The most trouble-some for me are mosfet with weird polygons.

author: tooki
author_rank: Super Contributor
timestamp: February 21, 2021, 06:36:13 pm
content: Quote from: SiliconWizard on February 21, 2021, 05:21:40 pm:::whoosh::: <— the sound of the point going right over your head.The point is that SOIC (JEDEC) and SO/SOP (JEITA)aren't the same thing.JEDEC SOIC narrow: 3.9mmJEITA SO: 5mmJEDEC SOIC wide: 7.5mmSo you can't say that "SO  without W is wrong"because it's not a wide version, it's the narrowest within its standard.Quote from: SiliconWizard on February 21, 2021, 05:21:40 pmNobody was claiming otherwise. I was adding info toclarify.Quote from: SiliconWizard on February 21, 2021, 05:21:40 pmBut it's not vendor-specific sizes (the OP's suspicion), it's that there are various industry standards that vendors use.Quote from: SiliconWizard on February 21, 2021, 05:21:40 pmWrong. The fact that some of the part suffixes are the same as their package codes does NOT mean they're the same thing! If you'd finished reading the paragraph you cropped at "…NOT the part suffixes", you'd have understood this.Everypart has a part suffix, not just some of them!! It's just that the part suffixes and the package codes may be the same, but also may not be. (Thanks to TI having acquired many other semiconductor manufacturers over the years, whose part numbers they had to keep, the TI package codes and the part number suffixes aren't consistent.)For this part, the N, J, and Dpackage codescorrespond to the E, F, and Mpart suffixes, for plastic DIP, ceramic DIP, and SOIC, respectively.If one doesn't care how the IC's are wrapped (i.e. tube, tray, reel size, etc), then referring to the Device Information table on page 1 of the datasheet is sufficient to ensure you order the IC in the correct package.

author: tooki
author_rank: Super Contributor
timestamp: February 21, 2021, 06:53:08 pm
content: Quote from: exe on February 21, 2021, 06:19:04 pmMany of them do, such as EasyEDA and Altium.But moreover, component vendors often supply the footprints, schematic symbols, and 3D models via component footprint services like UltraLibrarian, SnapEDA, or SamacSys. For example, you can go to Digi-Key, and for many parts they have a link to the footprint download. And if they don't, check the manufacturer: they often have it.For example, if you go to TI'sproduct pagefor the IC which is the subject of this thread, then scroll down to Design and Development and click CAD/CAE symbols. When you click the link for the package you want, it takes you to the correct page on UltraLibrarian, where you can choose a variant if applicable, then download it. It offers a gazillion formats. Diptrace appears to be able to import Eagle footprints, so you'd download in Eagle format and then import it.(A post I saw appears to indicate that SamacSys has native Diptrace export, so that might be an easier go-to for you. Mouser, for example, uses SamacSys.)

author: exe
author_rank: Unknown
timestamp: February 23, 2021, 09:53:02 am
content: Quote from: tooki on February 21, 2021, 06:53:08 pmI just did that and it worked, thank you.

author: exe
author_rank: Unknown
timestamp: February 26, 2021, 09:39:48 pm
content: Oh boy, I just used ultralibrarian for max6226, and it has wrong pinout. The pin 8 marked as GND, but it really is "Do not connect anything to this pin" (c) datasheet. You can check it here:https://app.ultralibrarian.com/details/4f419cec-7cff-11e9-ab3a-0a3560a4cccc/Maxim-Integrated-Products/MAX6226ALA25-T.It's funny that they claim "Built to the Highest Standards" and "all of our available components have gone through a rigorous verification process". Worst part of it is I don't see how I can report this. They have a contact form on the website, but they want my company name and phone number. Nonetheless, I submitted them a comment, but all I got back is "The website that you're trying to reach is having technical difficulties and is currently unavailable".Moral of the story: do not trust component libraries.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 27, 2021, 07:29:04 am
content: Quote from: exe on February 26, 2021, 09:39:48 pmThis, this, this! Always, no exception. Whenever you think you finally found that really professional library service youreallycan trust, the next day you are reordering your PCBs because the footprints are wrong, again.It's not a good idea to repeat the same mistakes all over again.Just draw the footprints from the component datasheets. For additional security, cross-check against supposedly similar competitor part datasheet drawing and see what the differences are.Once you get into this habit, it won't take long with any proper CAD tool.

author: exe
author_rank: Unknown
timestamp: February 27, 2021, 09:58:46 am
content: Quote from: Siwastaja on February 27, 2021, 07:29:04 amWell, I did mistakes while drawing them. Sometimes drawings require a lot of calculation because they specify only "required" dimensions.Verifying dimensions against the datasheet is easier because there is a ruler in my EDA. It takes me less time.Anecdote story: datasheet for a push button lacked drawings for exact part number that I bought. I had to measure the actual device.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 27, 2021, 12:59:22 pm
content: Quote from: exe on February 27, 2021, 09:58:46 amExactly, and this is why library parts are risky: someone did draw them, making mistakes in the process!The difference is: you are a professional / a hobbyist designer who's project's success depends on the suitability of the footprints. You are motivated to get them right, possibly even well paid for your time. You re-check for just that particular part. Often you even have the physical part to check against. So it's to be expected you are better on average than some anonymous intern somewhere who was just tasked to draw 1000 footprints. Or worse, someone just combined some re-re-re-labeled footprints that have been lurking around for decades under different names, from different EDA tools. If your success rate in creating a correct footprint is like 99%, some library may have just 90%, which is a disaster.In either case, it's best to recheck the footprints at a different design stage than when the footprints were first drawn. For example, measure from the Gerber output, comparing to a physical part you ordered for prototypes. Fresh set of eyes help.

author: phil from seattle
author_rank: Super Contributor
timestamp: February 27, 2021, 07:08:36 pm
content: Quote from: Siwastaja on February 27, 2021, 07:29:04 amDitto. Essential skill for a PCB designer. Just do it.Back in the old days of Eagle there were so many bad footprints out there that I got in the habit of making my own. Footprint editor on one screen, datasheet on another. Pretty easy and fast once you do it a couple of times.Drawing a good footprint from a datasheet is not very hard at all. You just need to get creative with grid size and be smart about picking your origin. For complex ones, have a spreadsheet open on another screen. Eagle has a user definable alternate grid available - hold alt down and get it. Works pretty well. In Kicad, I use property sheets to set exact size, location. Even big, complex parts are pretty fast.The point about checking competitive offerings is a good one. I will tweak a given footprint to make sure it will support alternate chips so I can use them without PCB redesign.

author: gnuarm
author_rank: Super Contributor
timestamp: February 27, 2021, 07:34:10 pm
content: Quote from: nctnico on February 21, 2021, 04:50:39 pmThe LCSC photos are often wrong as are their descriptions (although they are mostly just incomplete). I've always wondered who provides the inputs for the disti's data bases. I suspect it is from the manufacturer rather than the disti. In the case of LCSC I suspect it is LCSC and they seem to put little effort into it. Digikey and Mouser are much, much better. The both also have a link on every web page for you to report errors which I frequently use. They both are very responsive in fixing problems even fixing common problems across a product line rather than the single item you might report. Digikey rocks!

author: gnuarm
author_rank: Super Contributor
timestamp: February 27, 2021, 07:39:55 pm
content: Quote from: Siwastaja on February 21, 2021, 05:02:56 pmAll great advice. The sort of thing normally learned the hard way.One of the things that is hard to get hobbyists to accept is that they should just bite the bullet and enter their own footprints and thoroughly check them. As you say, do you want to deal with your own mistakes or deal with other's mistakes? The time spent vetting someone else's footprint is nearly as bad as just doing it yourself.I wish there was more reliable info on how to turn package dimensions into a footprint. There are recommendations, but they even vary depending on mode of assembly and your "process". So in other words, no real standard. I was surprised to learn manufacturer recommendations are different between capacitor and resistors of the same size!

author: gnuarm
author_rank: Super Contributor
timestamp: February 27, 2021, 07:48:29 pm
content: Quote from: exe on February 27, 2021, 09:58:46 amYeah, companies who can't be bothered to publish a proper data sheet don't get my business. I'm just not going to risk a design success for a part that may or may not match a datasheet if they can't be bothered to provide the datasheet data that the part may or may not match on any given day.