Are my new smd electrolytic caps rejects? - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: May 07, 2025, 11:07:16 pm
content: I brought some smd electrolytic caps from ebay , I find normaly tthe cap legs (looking down from the top) stick out about 1mm from the edge of the square plastic base so they can be soldered using a fine tip iron ,on my new caps the legs are totaly flush with the edge of the plastic base leaving nothing to solder onto with a fine tipped iron , Are they supposed to be that way or have i been sold rejects?.

author: thm_w
author_rank: Super Contributor
timestamp: May 08, 2025, 12:29:31 am
content: Part number or link?Some will have longer leads than others. Some are incredibly short but I haven't seen them flush:https://www.elfadistrelec.no/en/smd-electrolytic-capacitor-wcap-asll-10uf-50v-20-wuerth-elektronik-865060643005/p/30228196

author: JustMeHere
author_rank: Frequent Contributor
timestamp: May 08, 2025, 12:34:00 am
content: Don't use a fine tipped iron. Use a bevel or knife tip. Use the largest one that will fit into your work area. For SMT you really should be using hot air.

author: ME
author_rank: Frequent Contributor
timestamp: May 08, 2025, 12:35:46 am
content: this is what i got :https://www.ebay.co.uk/itm/265246503250

author: radiolistener
author_rank: Super Contributor
timestamp: May 08, 2025, 02:23:25 am
content: yes, most of things on aliexpress and ebay are factory reject or very bad quality. Good one will cost much more expensive.

author: wraper
author_rank: Unknown
timestamp: May 08, 2025, 02:38:06 am
content: Quote from: radiolistener on May 08, 2025, 02:23:25 amFactory rejects is a stupid myth. Parts are either what they say they are, counterfeits (including relabeled genuine parts), or salvaged e-waste sold as new. Chance of stumbling on actual factory rejects is lower than being hit by a car. Anyway, don't buy components on ebay or aliexpress unless you cannot reasonably get them anywhere else.

author: radiolistener
author_rank: Super Contributor
timestamp: May 08, 2025, 02:44:22 am
content: Quote from: wraper on May 08, 2025, 02:35:15 amFactory rejects are not myth and should be considered as a main risk. However, they are not the only concern, buyers may also encounter low-quality counterfeits or genuine components that were factory rejected due to improper storage conditions, such as oxidized or corroded contacts. While it is possible to find authentic, high-quality components on platforms like ebay or aliexpress, their prices are significantly inflated due to marketplace fees, Chinese import taxes, and seller margin.The main issue with these platforms is that even if you have already received a batch of good-quality components from a seller, it does not guarantee that the same seller will deliver components of the same quality in future orders.Quote from: wraper on May 08, 2025, 02:38:06 amApproximately 70-80% of my orders consisted of factory rejects - typically usable but often with some defects. Around 15-20% were of poor quality/not working at all and generally unusable. Only a small portion met acceptable quality standards, usually from lesser-known Chinese brands, but its a very low chance to get good one.For certain components, the likelihood of receiving counterfeits is extremely high, making factory rejects a comparatively better option. However, when purchasing items like transistors, there's a 99% chance of receiving remarked waste - at best, a lower-grade factory reject, at worst, random salvaged parts extracted from old equipment and re-encapsulated with markings that match your requested specifications.

author: wraper
author_rank: Unknown
timestamp: May 08, 2025, 03:28:04 am
content: Quote from: radiolistener on May 08, 2025, 02:44:22 amI'd like to see these ever eluding mysterious factory rejects at least once.

author: radiolistener
author_rank: Super Contributor
timestamp: May 08, 2025, 03:36:37 am
content: Quote from: wraper on May 08, 2025, 03:28:04 amjust put the order for some electronics components on ebay/aliexpress and you will get it.Upon receiving the components, perform a thorough inspection - you may discover mechanical or chemical defects, deviations from datasheet specifications, or unstable and malfunctioning behavior. This is pretty common issue on platforms like ebay/aliexpress.The defects are usually minor, and such components are generally suitable for hobby projects. However, they are not appropriate for standard production. For example, an assembly company may refuse to solder these chips after visual inspection, as doing so could involve additional risks or complications.

author: wraper
author_rank: Unknown
timestamp: May 08, 2025, 04:16:21 am
content: Quote from: radiolistener on May 08, 2025, 03:36:37 amThey are counterfeits, not rejects.. One part sold as another with fake marking. Factory reject means they come from original factory, they are not, they don't have the same silicon die inside them unless they are e-waste salvage. The only real rejects you can buy are low grade NAND FLASH chips sold by original manufacturer with marking applied afterwards by someone else to make them look like normal quality chips.

author: radiolistener
author_rank: Super Contributor
timestamp: May 08, 2025, 06:46:46 am
content: Quote from: wraper on May 08, 2025, 04:16:21 amYes, this is what I refer to as factory rejects - genuine components that were rejected during manufacturing and later resold. These components are typically either stolen or recovered from waste at the original manufacturing facilities. Some retain their original markings, appearing identical to standard parts and containing authentic dies, but they may have defects or just doesn't fit specification. Others exhibit more serious issues and are often remarked or repackaged as different components.In addition, it's quite common to encounter otherwise genuine components that were stored under improper conditions - such as high humidity - and subsequently rejected during incoming inspection at production facilities. These parts may exhibit soldering issues or corrosion-related defects that can impair their functionality, making them unsuitable for industrial use.For example, you can buy factory genuine branded ultra-high Q RF capacitors that were stored in poor conditions and subsequently rejected during incoming inspection at production facilities. This is usually not mentioned in the listing description, but you may notice indirect signs - such as visible corrosion or indications of long-term storage. While these components may still perform well and meet specifications, they can present challenges during soldering.This is how the component market operates - defective parts are resold to hobbyists on platforms like ebay/aliexpress, sometimes at prices comparable to high-quality components from reputable suppliers. However, while reputable suppliers typically require bulk orders, Chinese sellers on ebay/aliexpress allows purchasing in small quantities, making it more accessible for individual buyers despite the quality risks.You can also find high-quality branded components, but their prices are typically 1.5 - 2 times higher than those from EU distributors. This is due to import duties imposed on Western-brand electronic components entering China, along with marketplace fee and seller profit. Any lower-priced options are typically factory rejects or, in worse cases, low-quality counterfeits.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 08, 2025, 04:01:02 pm
content: Getting factory rejects is rare. The parts found on the platforms are more like NOS part and left-overs at manufacturers. So like 1/3 roll of capacitors that are left over or parts that where stored too long and than sold of for a bargin as they would need extra testing and little regular market.The parts may be perfectly fine, but they could also be bad (like oxidized, need bake out because of humidity levels, old electrolytics) - usually not bad from the factory, but more like bad from storage.With some parts, especially hyped audio parts, there are counterfits - especially send directly from China.The prices vary a lot - from higher than regular suppliers to really cheap. The good offers are often with more exotic parts (e.g. odd value resistors, obsolete RF chips) with a very limited market.

author: thm_w
author_rank: Super Contributor
timestamp: May 08, 2025, 10:06:52 pm
content: Quote from: ME on May 08, 2025, 12:35:46 amLooks OK, can see the leads are a bit short in the photo. In the future I would recommend ordering from digikey or LCSC, and order something with longer leads if that is what you need. Or switch to a through hole cap, better soldering iron, etc.Maybe these are longer:https://www.lcsc.com/product-detail/Aluminum-Electrolytic-Capacitors-SMD_KNSCHA-RST47UF16V034_C4747957.html?s_z=n_47uf

author: Haenk
author_rank: Super Contributor
timestamp: May 09, 2025, 10:29:44 am
content: Quote from: Kleinstein on May 08, 2025, 04:01:02 pmI purchased quite a few parts from Taobao. There *is* junk or plain fakes, that's without question, but mostly it is a overstock. Remember: They make a billion electronic devices in China per year, and certainly order a couple of percent extra parts. E.g. I got some nice branded caps, made by Nichicon, for Onkyo and Yamaha. Not in "mint" condition, but I don't care about a couple of minor scratches. Too cheap to be fakes (even by chinese standards), but way cheaper than similar Nichicon parts. When Onkyo or Yamaha makes 50000 devices, they don't order 50000x2 of those caps, but maybe 1000 extra, just to make sure, they have some extra stock for repairs, or to replace damaged-during-assembly ones and so on. After a while, these just end being sold to a broker, then sold on the market.Similar with resistors, ICs and so on - all these parts do have a rather short shelf life, and will not be used by assembly houses any more, once shelf life is expired. Plus, the overstock is usually a fraction of a roll/box - they would have to count parts, keep track on the inventory and so on - it's just cheaper to clear the inventory.

author: Psi
author_rank: Super Contributor
timestamp: May 09, 2025, 10:50:49 am
content: Quote from: wraper on May 08, 2025, 02:38:06 amFactory e-waste and Factory rejects are the same thing.The failed items get put into e-waste by the factory and sent to be destroyed/recycled unless someone in the chain decides to break the rules by taking them out and recycling them back onto the market as-is.A lot of the time they are supposed to get shredded when going into e-waste to prevent this but not all factories are as careful and sometimes steps get intentionally forgotten

author: wraper
author_rank: Unknown
timestamp: May 09, 2025, 11:08:14 am
content: Quote from: Psi on May 09, 2025, 10:50:49 amWho said it's a factory e-waste? Those are parts desoldered from discarded devices. Often with terminals cut off and new ones welded to make them look like brand new.

author: Seekonk
author_rank: Super Contributor
timestamp: May 09, 2025, 01:05:00 pm
content: I bought some electrolytics once and the leads were what I believe were aluminum. They couldn't be soldered to! These must have been intended to be spot welded.

author: UnijunctionTransistor
author_rank: Frequent Contributor
timestamp: May 09, 2025, 01:24:38 pm
content: 10 pcs for £2.79 ?Purchasing from a legitimate company would have cost you similarly.SMT lo-voltage electro-caps are ubiquitous and thus inexpensive.

author: wraper
author_rank: Unknown
timestamp: May 09, 2025, 01:33:01 pm
content: Quote from: ME on May 08, 2025, 12:35:46 amThis seller seems to be selling film and electrolytic caps exclusively from jb Capacitors and actually provides series in the descriptionhttps://www.jbcapacitors.com/wp-content/uploads/pdf/JCK-1000H-to-2000H-at-105-SMD-Aluminum-Electrolytic-Capacitor.pdf(yes, terminals should normally be this short).So apparently a pretty decent seller, not as Chinese sellers selling random crap. But still it's better to get parts from LCSC. If you order enough stuff as once to get decent goods cost/shipping rate, it will be cheaper and way more certain of what you get.

author: JohanH
author_rank: Frequent Contributor
timestamp: May 09, 2025, 01:37:20 pm
content: For an experiment I bought a batch of 50 SMD tantalum capacitors from Aliexpress, all 1000 µF 6.3V, supposedly Kyocera AVX 7343E, 10%. I knew they couldn't be as good as genuine, because they were so cheap. I measured them all.Lowest capacitance 679 µF (32% under nominal)Highest capacitance 902 µF (9.8%)Average capacitance 816 µF (18.2%)Only three capacitors out of the 50 were at the limit of the 10% tolerance, or if we are picky, only one at 902 µF. The rest were between 12% and 32%.These were either clones of some sort or rejected due to bad tolerance. I've no idea. But they still worked for my purpose.

author: CaptDon
author_rank: Super Contributor
timestamp: May 09, 2025, 01:52:30 pm
content: During the days of vacuum tubes and the time frame of early '60s to mid 70's some of the major manufacturers sold their 'fall-outs' to resellers that rebranded them. These defects were various like poor gettering action leaving trace gas, improper filament current draw for series controlled warm up tubes or batches incorrectly assembled. These re-branded dubious quality tubes often were sold at the drugstore tube testing machines with names like RAD-TEL vs. TELRAD vs. KENRAD and so forth. Note that in GE's Ham Radio News there was an article about GE crushing all of their non-conforming tubes and never releasing sub-standard tubes to resellers. In the I.C. world we see factory fallouts (rejects) being sold or stolen for resale. These usually are functional but fail read/write speed specs or output current specs or they fail those specs near the rated temperature extremes. At ISSC in York Pennsylvania we were doing 100% incoming inspection using specially designed equipment from Fluke. At GE Locomotive we had to do 100% QA/QC testing on our chinese contract manufactured boards. They were 'supposed' to be temperature cycled and burned in at the factory as well as electrically tested and each process had a 'stamp'. We received boards that could have never worked containing wrong parts and counterfit failed components!! We destroyed the boards locally, why you ask? Because we sent them back to the CM to be repaired and we got the exact same failed boards back in the next shipment!! Buyers Beware!!!

author: CaptDon
author_rank: Super Contributor
timestamp: May 09, 2025, 01:58:21 pm
content: As a side note to your post, SMD tantalum capacitors are almost never up to their rated capacitance when testing at their rated voltage. I learned that the hard way when I was seeing about 50% capacitance in a project that ran them very close to their 'rated' working voltage. I believe this is a well understood phenomena.

author: MissionCompleted
author_rank: Newbie
timestamp: May 09, 2025, 02:01:39 pm
content: Hi everyone, I’m new here!I’ve been reading this thread and I think the truth is somewhere in the middle. Sure there’s a lot of junk on eBay and Aliexpress, but you can also find decent leftover or extra parts if you know what to look for.In my opinion, the real problem isn’t "factory rejects" but the fact that you just never know what quality you’re getting on these sites. It’s a bit of a gamble. For serious projects I’d always buy from trusted stores like Digikey or Mouser. But for hobby stuff or experiments, cheap AliExpress parts can work fine - you just need to expect some bad ones and check everything yourself.I think in the future we’ll see more demand for better-rated sellers and more control over quality. For now, we mostly have to rely on experience and helpful forum talks like this.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 09, 2025, 06:05:35 pm
content: Quote from: MissionCompleted on May 09, 2025, 02:01:39 pmI never understood this argument. Hobbyists areoften(not always of course) beginners or less experienced than professional designers, so less able to understand what is wrong with their circuits. Trying to troubleshoot all day thinking that something is wrong in your schematic or construction, assuming that your components are good, is horrible and demotivating.So I suggest that hobbyistsespeciallytry to buy from well known distributors. Professionals may have better understanding and chances to do risk analysis and component testing.Of course the real issue is with shipping costs. If you want to buy $5 worth of components at once and not pay $20 or whatever for shipping, then you go to Ebay and I understand that, but let's not kid ourselves with rationalizations like "they are good enough for hobbyists".Then again, when it was a new thing to buy Chinese counterfeit crap from Ebay (circa 2008 or so) I realized I had wasted over $500 on crap within less than a year. With that money, would have made free shipping minimum order to Digikey or others once a month!

author: JohanH
author_rank: Frequent Contributor
timestamp: May 09, 2025, 07:27:20 pm
content: I'm only a hobbyist (with electrical engineering background), but I've also realized there's no point in wasting money on cheap and unknown components, except for experiments. When I build a device that I intend to use, then I order most components from Mouser or similar.

author: radiolistener
author_rank: Super Contributor
timestamp: May 10, 2025, 03:15:46 am
content: Quote from: Siwastaja on May 09, 2025, 06:05:35 pmthat's true, but aliexpress sometimes allows you to buy something at cheaper price and acceptable quality. Counterfeit and factory reject doesn't not means that its always very bad, some things are good enough for their price. And you have option to open dispute and return the money if they send you complete crap.

author: wraper
author_rank: Unknown
timestamp: May 10, 2025, 11:33:59 am
content: Quote from: radiolistener on May 10, 2025, 03:15:46 amAliexpress allows you to be an idiot. If you want cheap parts, buy honest Chinese parts with known spec, not a cat in a sack. Also it's false economy. What a point of buying a lot of 50 counterfeit parts for the price of 10 genuine if you won't use more than 5 anyway? Collecting a stockpile of junk?

author: Fflint
author_rank: Frequent Contributor
timestamp: May 10, 2025, 12:58:26 pm
content: Quote from: wraper on May 10, 2025, 11:33:59 amGood luck buying certain parts anywhere else than Aliexpress. For example Mitsubishi RF transistors like RD01MUS2 or MUS1. And many other older parts that are cheap and pretty good for hobby projects. They are all "deprecated" and unavailable anywhere else.Samegoes for older bigger ldmos like mrf186.Then there is cost of parts. Hi Q RF SMD caps were mentioned. These cost up to a couple EUR each in small quantities. It is perfectly fine in my book to buy "recycled" ones like these I ordered a month ago:This is about $10 shipped for 20.It really depends on the parts and project. My first choice is Mouser, but if prices are too bad or it hasn't got the parts... Aliexpress for the rescue.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 11, 2025, 07:21:07 am
content: Yes, sometimes you just have to buy from Aliexpress/Ebay due to lack of better sources (or difficulty of buying, super expensive shipping etc.).But do yourself a favor and don't buy any of the following:* Normal ICs (voltage regulators, opamps, etc.)* Transistors like usual MOSFETs* LEDs* Electrolytic capacitorsThis is all easily available at proper distributors (and if you want Chinese, there is LCSC) at approximately the same cost.I have seen >90% unusable crap rate on those. Voltage regulators that output wrong voltage, MOSFETs with 5x the rated Rds_on, broken LEDs or some that work for a while and die. Electrolytic capacitors I never bought hearing from experience of others.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: May 11, 2025, 09:04:33 am
content: Quote from: ME on May 08, 2025, 12:35:46 amThe guys at Switch Electronics are pretty honest and reliable, I have bought many items from them with no problems at all. Rapid sell the same capacitors, which are listed as discontinued, hence why Switch Electronics are selling them cheaply. This is the data sheet, which shows the capacitors and their very short "tabs". They are listed as designed for reflow soldering, not hand soldering.https://static.rapidonline.com/pdf/565677_v1.pdf

author: factory
author_rank: Super Contributor
timestamp: May 11, 2025, 12:55:50 pm
content: Quote from: UnijunctionTransistor on May 09, 2025, 01:24:38 pmPrice will include feeBay sellers fees, not free for UK business sellers and UK postage/packing costs, again not free for the seller, seller still has to make a living too, cost of the capacitors is probably the smallest percentage of all that.