Dragging soldering SMD: lots of damaged chips?! - Page 1
Forum section: electronics / projects

author: Alteregoxxx
author_rank: Contributor
timestamp: November 13, 2020, 07:37:33 pm
content: Hello,for a couple of projects, I need to test out various smd ic (opamps, muxes, instrumentation opamps) on a breadboard; it's just to speed up things, avoiding designing a pcb, waiting for the production and shipment times required by a pcb farm, waiting for the customs times etc etc, just for a couple of tests.So, I bought a bunch of SOP/TSSOP/MSOP( 8 and 16 pins) to PDIP adapters and started to soldering on them various chips: TMUX1208, TMUX1108, TSH82IDT, OPA365AIDR, AD8237With my great surprise, testing on a total of about ten soldered IC, just a couple of them, one TMUX1108 and one OPA365AIDR, were correctly functioning: the remaing ICs were all behaving or in a randomly way or in a "momentary stable way" (in the sense that some of them were stable just for 10-30 seconds from the power on then also them have becoming unstable)!!I already checked the following aspects:Triple checking of all the datasheets for assuring the correctness of the pinout/connectionsTriple checking of the value and stability of all the involved power supply (+5V and +3.3V)Soldering station temperature accuracy using thermocouple: triple checking using three different thermocouples, stable and spot on 285 °CReliable grounding of the soldering tip: triple checking, working perfectly, resistance to earth ground less than 5 Ohms.All the hand soldering work has been performed as fast as possible to avoid overheating, using rosin flux, a T12 BCM3 soldering type tip at 285°C, using dragging soldering, hence remaining surely less than 1 seconds on each pin of the chip.Cleaning of the flux residual using F-02 Anti-flux made by "DUE CI ELECTRONIC", then waiting for the complete and perfect evaporation of the solvant before turning on the chip.Before turning on the ICs, test of all the pins with multimeter for short and/or open circuit: triple checking, all soldering joints were perfectly working, no short circuit between the pins.I'm going mad of what could be causing such an high failure rate!Any expert hint that is going to save my mental healt ?!

author: Yansi
author_rank: Super Contributor
timestamp: November 13, 2020, 07:39:44 pm
content: Your soldering is probably the failure cause. To get more help from us, show us a detailed macro photo of how the pins got soldered.

author: E-Design
author_rank: Regular Contributor
timestamp: November 13, 2020, 07:44:21 pm
content: Show a pic of one of your misbehaving setups..Could be any number of things... I will include some ideas.1) Bad connections from your dip module to your what? Breadboard below? Check those power supply voltages. You soldered chips on carrier boards but how are you powering them?2) oscillations on opamps due to big loop areas / noise pickup etc... again where that pic3) Are the parts you purchased from a good source? i.e. are they suspect grey market / aliexpress bottom barrel chinese specials?Focus on troubleshooting ONE particular intermittent instance.. when you find that root cause, likely it will be the same story for your others.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 13, 2020, 08:16:46 pm
content: any hint on the circuit's schematics, pictures of the setup etc to save our mental health?

author: Alteregoxxx
author_rank: Contributor
timestamp: November 13, 2020, 09:12:02 pm
content: Hello guys,thanks for the very fast feedbacks, really appreciated!Just to answers some of your questions:Parts comes from a very respectable source: MouserI was not trying to implement any particular complex circuit, yet: I was just testing the ICs one by one in their respective simplest possible configurations, examples:Opamps (TSH82, OPA365AIDR), tested as unity gain buffer: Supply +5V and ground, non inverting pin at +3.3V --> checking for the output being +3.3VMuxes (TMUX1108/1208), simple channel testing for muxes: Supply + 5V and ground, address pins A0,A1,A2 at ground, all Sn channels pins pulled up at +3.3V, alternating+3.3V and 0V signal on pin D--> checking that S1 channel was following the signal on D (same test repeated for all the other A0,A1,A2 address combinations)Find attached the only soldering joints macro picture I made today in the morning (here in Italy now its late evening, I need some good light to make other pictures, macro photography ask for a lot of light unfortunately)Find attached also another picture showing how the adapter is tyipically mounted on the breadboard (on this specific picture on the adapter is soldered an OPA365AIDR, single channel opamp)I have tested also on other breadboards that I have (brand new): same story.Power supplies, +5V and +3.3V, comes from two LDO regulators (AMS1117): triple checked them for stability, noise etc etc using a scope, their current capability tested too, perfect.

author: WattsThat
author_rank: Frequent Contributor
timestamp: November 13, 2020, 10:40:22 pm
content: 1) Pin 1 at the ic package appears to be unsoldered.2) Those round molded end jumper wires are absolute crap. Use solid #22 hookup wire for breadboard connections. Even when good, they’re very high resistance due to the very fine strands of what I doubt is copper. They tend to be intermittent with very little use. Save the headaches and throw them away, they’re that bad.3) 1/4 watt Chinese resistor leads are many times too small for the breadboard terminals.4) The leads from the Analog Discovery are fine as are square pin “DuPont” jumpers. But those very thin gauge round molded end jumpers are very problematic as already mentioned.

author: Mechatrommer
author_rank: Super Contributor
timestamp: November 14, 2020, 08:47:06 am
content: Quote from: WattsThat on November 13, 2020, 10:40:22 pmi've used that for years. the only issue that i need to understand is rusted end connection in storage, so when in use i'll clean them off first. to OP, we still cant figure out what exactly problem, still too broad case and many possibilities, maybe explaining one case problem may help us to help you.

author: Miti
author_rank: Super Contributor
timestamp: November 14, 2020, 10:49:33 am
content: Most likely the adapters and the chips are fine. It’s your breadboard or the wires that are trouble. Those are total crap, I gave up on breadboards long time ago. And those wires, I thought I’d go mad trying to make an LCD work with Arduino using wires bought on ebay. Then I replaced them with some better ones, plugged directly into the adapter pins, and everything worked as intended.

author: Alteregoxxx
author_rank: Contributor
timestamp: November 14, 2020, 03:05:46 pm
content: Ok, I'll try to give you more clear information.Find belowA picture that is a collage of pictures of 4 of the non working ICs for soldering inspection: there are 2 TSH82 opamps (distinguished by the added postfix "instance1" and "instance2") and 2 TMUX1208 (same as before, instance1 and instance2)A picture of the circuit made on the breadboard using TMUX1208_instance1: as you can see from the picture, A0, A1 and A2 address pins are all at +3.3V, hence the only selected channel of the mux is S8, all the other remaing channels, from S1 to S7, are unselected and pulled up at +3.3V.Oscilloscope probe C1 is attached to the mux S8, oscilloscope probe C2 is attached to mux S5: find attached a video (gif) of the scope acquisition.As you will see from the video, the S5 mux channel really is unstable despite being pulled up at +3.3V from the 6.8K resistor: this behaviour I captured comes and goes at irregular times; right after I did capture the video, in fact, it has been stable for about a couple of minutes...than it becoming unstable again for maybe 1-2 minutes...or ten..who knows......and so on...Moreover, the remaining inactive channels, also are doing "bizarre" things: for example S6 and S7, tend to "follow" the value of S8 signal, not perfectly equal to S8 however, while they should stay stable and pulled up at +3.3V, S1 and S2 seemes to be dc stable, but not at +3.3V like they should be, instead they are, more or less, at 2.7V one, 2.9V the other...I have to emphasize that, despite I agree with all of you that have said that jumper wires are really bad evil ( I really learnt that lesson lots of years ago, I know, hence for more "sensible" stuff I always use solid core and/ore make my own dupont cables), I've checked for goodness of all the jumper wires you can see in the pictures: all of them have a resistance slightly below about 300mOhm. Moreover I've checked also for continuity after having them inserted in the breadboard hence I can assure at 99.999999% that we're not looking at a bad cables/bad breadboard case study.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 14, 2020, 03:11:36 pm
content: Soldering looks mostly OK. It doesn't need to be perfect. Heat damage especially requires horrible abuse like setting the iron at 400 degC and wasting a minute doing a solder joint.Definitely not the cause:* heat damageLikely not the cause:* ESD (you are seeing too high failure rate; ESD damage tends to be awkwardly rare and ruin your day once a year, or 1 out of 1000 production units; not all the time)Possible causes:* Unsoldered pins that look soldered* Any shorted pins (easy to check with multimeter)The most likely causes:* Using solderless breadboards. Do not use. Solder everything.* Using cheap jumper wires. Do not use. Solder everything. Use normal hookup wire, you can scavenge this from old ethernet cables.Get rid of all the excessive parts like the adapters, solderless breadboards etc., they are wasting all the time you think you are saving on less soldering. Instead, just solder everything, when needed, just dead-bug the chips, use hookup wire, and so on. As a side effect, you get better and quicker on soldering. Finally soldering is some 5% of the time in your prototyping; most goes into thinking what to do next, measuring, analysing results etc.

author: akimpowerscr
author_rank: Regular Contributor
timestamp: November 14, 2020, 03:44:13 pm
content: I never use breadboard, I'd rather waste a little more time soldering the components and jumpers on my testboard than looking for bad contacts.For integrated circuits, I install good quality sockets.

author: Alteregoxxx
author_rank: Contributor
timestamp: November 14, 2020, 03:45:34 pm
content: Quote from: Siwastaja on November 14, 2020, 03:11:36 pmAssuming you are right on the latter, it could not explain why if I swap, I've tried right now, the damaged TMUX1208_instance1 visible in the gif video with another one, the only TMUX1208 that seems to have "survived" to my soldering process, it works wonderfully: same breadboard, more precisely same position on the same breadboard, same jumper wires, same all, I've simply removed from the breadboard the TMUX1208_instance1 you've seen in the gif video and put in the other one, the one that I call affectionately "the strong survivor".

author: Vovk_Z
author_rank: Super Contributor
timestamp: November 14, 2020, 04:00:24 pm
content: I have resoldered small SMD (SOIC-8 and similar opamps) chips several times, and all of them where fine. So there is possibly some mistake in TS technology.

author: rstofer
author_rank: Super Contributor
timestamp: November 14, 2020, 04:21:16 pm
content: If you doubt the soldering, run a stripe of flux perpendicular across the pins and reheat the joints. The trick to drag soldering is the use of flux.ETA:I buy my flux in a syringe with dispensing needle. Applying a thin stripe is pretty easy.While I'm thinking about it, SolderWick is your friend. If the pads are shorted, apply some flux and use SolderWick to pull out the excess solder. Again, flux is the key!

author: Siwastaja
author_rank: Super Contributor
timestamp: November 14, 2020, 04:39:50 pm
content: Quote from: Alteregoxxx on November 14, 2020, 03:45:34 pmSound really odd, I don't know.The only way to go forward IMHO is to take the "failed" one, desolder the "failed" chip, and use it to build a new one (this time with minimized number of connectors, test leads etc.) See if it "surprisingly" comes back to life. If not, it really might be damaged, but I'd be surprised.Maybe somereallystrong ESD? Do you have an environment (typically dry and with suitable combination of flooring material and textiles) where you actually get static nuisance sparks?

author: Siwastaja
author_rank: Super Contributor
timestamp: November 14, 2020, 04:44:16 pm
content: Lack of power supply bypass capsnext to ICsseems a clear omission, so before you do anything else, fix that: add some 100nF ceramics right at the chip. The caps at the solderless breadboard won't cut it, they are too far down relatively high-impedance connections.Though, even this isn't necessarily the cause. Worth fixing anyway to bring number of unknowns down.

author: Alteregoxxx
author_rank: Contributor
timestamp: November 14, 2020, 06:34:53 pm
content: Quote from: Vovk_Z on November 14, 2020, 04:00:24 pmWhat do you mean with "TS technology" ?

author: Alteregoxxx
author_rank: Contributor
timestamp: November 14, 2020, 06:47:51 pm
content: Quote from: Siwastaja on November 14, 2020, 04:44:16 pmI appreciate your suggestions, thank you :-)Nevertheless, even if I agree with you on the fact that cap bypass is largely more effective if placed right at the chip, consider also that1)here I'm not applying any strong switched signal, instead, a "smooth" sinusoidal signal at a very low freq, 1Khz, hence I don't think bypass caps2) Ineffective as it can be, there is, however, a 100nF film cap on the breadboardFinally and more important than the previous points, I still ask the same question: why, in the same identical conditions, "the strong survivor" TMUX1208 works perfectly while the TMUX1208_instance1 behavior is completely wrong ?This is really the reason I'm more than confident that breadboard and jumpers are clearly not the culprit....Do you agree?

author: Siwastaja
author_rank: Super Contributor
timestamp: November 14, 2020, 06:52:03 pm
content: Yes I kinda agree with what you say, but in my experience soldering damage is so freaking rare - I have never damaged, or seen anyone damage an IC without there being clearvisiblephysical damage like broken-off legs - this includes myself desoldering gate drive ICs off motherboards with 450degC heat gun so that the FR4 actually catches fire and the ICs drop to the floor, then happily reuse those ICs. And given your description of your soldering temperatures you already verified, I have hard time believing it's the problem either.Very strong ESDcouldbe, but I'm still suspicious.So I would like to see a confirmation that the ICreallyis dead. If nothing else, desolder both the working and "broken" chip, swap the carrier boards, resolder, and see if the problem moves to the another board. This shouldn't take too many minutes to test.Bad Ebay specials would be an easy explanation but you are saying they are from Mouser...One possible surprising cause would be an excessive, non-current limited voltage on your soldering iron tip: you often see LEDs light up a tiny bit when soldering them. If the current is excessive, it can damage the hot ICs. But there would need to be a return path for this current somehow...

author: Alteregoxxx
author_rank: Contributor
timestamp: November 15, 2020, 09:56:01 am
content: Quote from: rstofer on November 14, 2020, 04:21:16 pmAlready did that, flux + reheat of the joints: same story, the ICs that did appear as they were "damaged" did stay "damaged", even after the reheat.Quote from: Siwastaja on November 14, 2020, 04:39:50 pm"Unfortunately" never experienced any static nuisance sparks...The idea do desolder the apparently bad chip, desoldering "the strong survivor" and resoldering both after having swapped the adapters on which they were soldered coul surely be a good one, just to exclude that the culprit could be the pcb adapter....still, as I have previously said, for all the chips I have soldered, after having soldered them, I have checked for continuity between the adapter pins header and the smd chip leads and, "unfortunately" all of them were (and are) perfectly good, despite the chips behaving very bad when turned on....By the way, I've already ordered from Mouser some soldering past (with lead, just to minimize required temperature nedeed for the reflow) and no clean flux (the one I have is very very old flux, years old, rosin based...I don't know...maybe it the culprit?) and lots of TMUX1208: I'm going to solder 5 of them on the adapters using hot air soldering, solder past and the new flux, then other 5 of them using hot air, solder paste and my old rosin based flux, then other 5 of them using solder paste, no clean flux but using drag soldering etc etc, considering all the possible combinations...I'm mad, I know, but know it has become a matter of principleMaybe a little bit of statistics will emerge to help us in slving the mistery...who knows.... what do you think?

author: Wolfram
author_rank: Frequent Contributor
timestamp: November 15, 2020, 10:32:38 am
content: Do you have any resistance in series with the 3.3 V rail being fed to the IC inputs? Connecting IC pins directly to a different voltage rail than they are powered from is a bad idea, unless you can absolutely guarantee that this rail powers up after the IC supply rail. For the TMUX1208 for example, the absolute maximum voltage rating for the S pins is Vdd + 0.5 V, this can be exceeded in your circuit if the 3.3 V rail is 0.5 V higher than the 5 V rail, which could happen during start-up depending on the regulators used and the amount of capacitance on each rail.

author: Alteregoxxx
author_rank: Contributor
timestamp: November 15, 2020, 10:57:42 am
content: Quote from: Wolfram on November 15, 2020, 10:32:38 amS pins are all pulled up to +3.3V using 6.8 KOhm resistors, no direct connection to +3.3V. Only the following pins -> EN, A0,A1 and A2 <- have direct connections (with direct I mean no trough pull up resistors) with +3.3V, but, as stated in the datasheet, TMUS1208 is guaranted to be a "Fail safe logic" mux type, meaning you can have those digital control pins "turned on" even befor applying power supply to the chip; quoting the datasheet here:QuoteHave I correctly interpreted your question?

author: Siwastaja
author_rank: Super Contributor
timestamp: November 15, 2020, 12:50:06 pm
content: Statistics seldom help solving such deep mystery, it's not a very good use of time IMHO. Instead, going for as deep down as possible to try to find the root cause, by stripping away excess parts one after one may provide you with something we all have overlooked.Yourlogicis correct in that if you have measured for continuity for all pins, and absence of shorts, swapping the ICs between the carriers should not change anything, and the logical conclusion is that the "faulty" chip indeed must be faulty.But being such mystery case, it would be nice to have thatconfirmedbecause we all may be missing something, and by definition, we can't know what we are missing.

author: Vovk_Z
author_rank: Super Contributor
timestamp: November 15, 2020, 02:16:49 pm
content: Quote from: Alteregoxxx on November 14, 2020, 06:34:53 pmI mean "Topicstarter soldering technology".

author: E-Design
author_rank: Regular Contributor
timestamp: November 15, 2020, 02:44:12 pm
content: In my 30 years experience dealing with soldering IC's... the chances that you purchased defective ones or damaged so many while soldering is pretty much ZERO.You should re verify any assumptions you still have about how you already verified.Swap out a defective chop with another and then swap it back again. Dont reheat joints... rebuild on eof you intermittent setups again completely. Get off that solderless breadboard to for testing purposes - eliminating one more possible failure cause..(if you hadnt done this already)

author: SilverSolder
author_rank: Super Contributor
timestamp: November 15, 2020, 03:05:21 pm
content: Not sure why everyone is so negative on breadboards... They usually work first time for me, I can't recall being "had" by a bad connection. I do avoid using "too thin" wires, though. Many components are SMD parts soldered to a 2 pin header, for example.My problem is usually a design that needs more thought!

author: Siwastaja
author_rank: Super Contributor
timestamp: November 15, 2020, 03:45:09 pm
content: Quote from: SilverSolder on November 15, 2020, 03:05:21 pmBecause of bad experience, of course. For me, both personal and overseeing others.You can buy proper ones (from 3M, for example), use high-quality jumpers (not Chinese Ebay Dupont) with them, and be careful not to ever damage them with TO220 leads or similar, and always use the correct wire size. Many do this professionally with no problems.In reality, non-professionals who use themoftenfail in some of the mentioned aspects, resulting inintermittentproblems. This doesn't always happen, and as a result, the experience varies, and the same discussion goes on.Please do not derail it this time. Thank you in advance.In this case, process of elimination is the only way to proceed, so eliminating the breadboard is obvious, regardless whether the probability of it beingthecause for the problem is 1% or 99% or something inbetween (I'd assume everybody here agrees it falls within this range. I'd say 42%). Even SilverSolder's quote says they "usually" work, so isn't it obvious it's one of the first things to eliminate? You know, when you have tried almost everything already, you need to be absolute 100% sure something works to decidenotto eliminate it, no?

author: fourfathom
author_rank: Super Contributor
timestamp: November 15, 2020, 03:54:44 pm
content: Quote from: SilverSolder on November 15, 2020, 03:05:21 pmAgreed. I use those breadboards for trying out circuits or throwing together a quick test fixture, and really have no problems. Sometimes I use those molded-pin jumpers, and have indeed found a few bad ones (open circuit), but that's easy enough to find and I throw out any bad ones.I've used breadboards to build quick 10 MHz L/C oscillators, and connect digital signals up to 150 MHz (with short jumpers) with no trouble. I wouldn't attempt to use them for precision designs where a few pF of stray capacitance or a few milli-Ohms of resistance would make a difference, but otherwise they work well for me.I recently prototyped a 48-pin SAMD controller, 8-pin SPI memory chip, and 100-pin LCC FPGA (with internal 200 MHz PLL) using similar boards as the OP, stuffed into a solderless breadboard, and it all worked well. I then had circuit-boards fabbed.Back to the OP's problem, I do suspect open solder joints. The first photo did look questionable. I often test my surface-mount chip connections with a DVM in the diode-test mode. I probe between Vdd or Gnd and each pin, and if I can't see the protection diode I touch up the solder on that pin. I then probe all adjacent pin-pairs, looking for shorts. Solder-wick cleans those up. I usually use my toaster-oven to reflow my boards, with solder paste applied by hand or with a stencil, but I also occasionally drag-solder. Drag-soldering a QFN part with (no exposed leads, just a small pad under the device) can be difficult, and it does sometimes take me a few tries before I can get the solder to bridge the joint.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 15, 2020, 03:55:59 pm
content: Quote from: fourfathom on November 15, 2020, 03:54:44 pmBut now there IS a problem, and almost everything has already been tried! This isn't about the probability of getting ten '6' when throwing a dice ten times in succession; it's about getting another '6' after nine '6' have already realized. If the probability of breadboard issue is 1% and the probability of soldering heat damage with properly adjusted soldering iron is 0.001%, you know how to proceed.Your comment is off-topic and totally unhelpful and only contributing to derailing this to yet another fight about solderless breadboards.

author: fourfathom
author_rank: Super Contributor
timestamp: November 15, 2020, 04:08:28 pm
content: Quote from: Siwastaja on November 15, 2020, 03:55:59 pmWhatever you say. While you were complaining, I was editing my response to include (I hope) more some helpful advice.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 15, 2020, 04:58:59 pm
content: I can't recall ever seeing a fight break out over a breadboard, LOL!Hey, we totally get that the breadboard is one of the suspects here.If it was me, I'd try to ascertain whether the chips really are blown or not by lashing up the simplest possible test fixture on a different board just to do a sanity check, powered by batteries only (to eliminate possible PSU issues).If the chips don't even pass the simplest test, order some new ones and do the same thing, being super careful about wrist straps etc. when soldering.

author: tooki
author_rank: Super Contributor
timestamp: November 15, 2020, 06:04:19 pm
content: Quote from: Siwastaja on November 15, 2020, 03:45:09 pmLife hack: use flat jaw pliers to twist the (thin part of) TO-220 leads by 90°, so they run parallel to the contact strip inside the breadboard. This makes them effectively thin enough to not distort the breadboard contacts.

author: 2N3055
author_rank: Super Contributor
timestamp: November 15, 2020, 06:23:41 pm
content: Quote from: Siwastaja on November 14, 2020, 04:44:16 pmThose are 100MHz and 50Mhz video amplifiers..They are GUARANTEED to oscillate without proper ground plane,decoupling and other precautions.They will OSCILLATE on breadboard with no decoupling and connected with 50 mm wires for power, guaranteed.They will oscillate regardless what signal is connected.You need to connect oscilloscope to output of amplifier and you will see oscillation..

author: bson
author_rank: Unknown
timestamp: November 15, 2020, 09:19:28 pm
content: Quote from: SilverSolder on November 15, 2020, 03:05:21 pmJamming square header pins into a breadboard is a good way to damage it.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 16, 2020, 01:29:02 am
content: Quote from: bson on November 15, 2020, 09:19:28 pmI guess I'm just lucky. Thankfully, luck counts as much as skill in life!

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 16, 2020, 02:17:48 am
content: Quote from: bson on November 15, 2020, 09:19:28 pmMaybe if you tried to force them in at a 45 degree angle, the width is about the same as the diameter of 22AWG solid wire often used for breadboard jumpers. Also note that most "breadboard friendly" modules use header pins to plug into the breadboard.

author: Alteregoxxx
author_rank: Contributor
timestamp: November 16, 2020, 09:03:04 am
content: Quote from: 2N3055 on November 15, 2020, 06:23:41 pmOk, so we are talking of the opamps now: I guess someone asked to restrict the filed of investigation, hence we were concentrating on TMUX1208.However, coming back to opamps just for a moment: TSH82 are for sure very fast opamp (GBW 100MHz) but OPA365 are too (50Mhz), right?Well, I soldered on adapters 3 opamps in total, 2 TSH82 and 1 OPA365: both TSH82 behaviour is "randomic", OPA365 is rock solid stable. Same breadboard same all.

author: thinkfat
author_rank: Unknown
timestamp: November 16, 2020, 09:46:07 am
content: What soldering station do you use? Is it mains isolated? Is it properly grounded? Is the tip properly grounded?If it's not mains isolated and not properly grounded (like a TS80 on a cheap USB QC3 charger), your tip will have significant potential against earth. Enough to damage the components you solder. You mentioned a "T12" tip, but not what station you actually use, hence my question.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 16, 2020, 09:51:01 am
content: It's also typical for such weird systematic problems that there is no single cause even though you are sure there is!For example, the high BW opamp might misbehave due to the circuit parasitics, the TMUX might be damaged by ungrounded soldering iron tip with Vmains/2 Y capacitor leakage voltage, and so on.Don't try to apply too much logiccomparingthings no matter how good that detective strategyfeels; instead, simplify and eliminate, like the misbehaving TMUX part was the only one you have! I once made a batch of 30 PCBs with the exact same accelerometer IC, and I thinktwomisbehaved weirdly. I was 100% sure it is either soldering issue, or bad ICs. It can't be my code, it's the same in all units! Finally, the problem was with my code and nothing else. 28 chips out of 30 worked with the slightly wrong code, two did not. Same IC batch.

author: 2N3055
author_rank: Super Contributor
timestamp: November 16, 2020, 10:29:59 am
content: Quote from: Alteregoxxx on November 16, 2020, 09:03:04 amOPA is 4x slower, it has 25V/us slew rate, and ths82 has 100V/us slew rate.. Fact that OPA365 seems not to oscillate is pure luck. If you go and change anything, rearange wires, hold hand close to it, change load etc. it might start oscillating too. It is probably very marginal..Breadboards can work for slow opamps, and slower logic (because logic is very resilient to crap). But if you look at logic signals with a scope, you will se all kinds of over and undershoots (that violate max specs for logic chips) resonances and ringing...It is good for quick proof of concept, but to see how the circuit will work in real world, you should commit it to real PCB as soon as possible.PCB is also component of your circuit. People keep forgeting that...In RF it might be THE component that defines how (or if at all) it works..Not to mention whole discipline of planar microwave circuits, that create capacitors, inductors, transformers baluns, filters, mixers, whole circuits, etc by using PCB layout...From datasheet (those are meant to be read):Layout precautionsTo make the best use of the TSH8x circuits at high frequencies, some precautions have tobe taken with regard to the power supplies.• In high-speed circuit applications, the implementation of a proper ground plane on bothsides of the PCB is mandatory to ensure low inductance and low resistance commonreturn.• Power supply bypass capacitors (4.7 µF and ceramic 100 pF) should be placed asclose as possible to the IC pins in order to improve high frequency bypassing andreduce harmonic distortion. The power supply capacitors must be incorporated for boththe negative and positive pins.• All inputs and outputs must be properly terminated with output resistors. Thus, theamplifier load is resistive only and the stability of the amplifier is improved.All leads must be wide and must be as short as possible, especially for op-amp inputsand outputs, in order to decrease parasitic capacitance and inductance.• Time constants result from parasitic capacitance. To reduce time constants in lower-gain applications, use a low feedback resistance (under 1 kΩ).• Choose the smallest component size possible (SMD).• On the output, the load capacitance must be negligible to maintain good stability. Placeca serial resistance as close as possible to the output pin to minimize the effect of theload capacitance.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 16, 2020, 01:44:08 pm
content: Quote from: Siwastaja on November 16, 2020, 09:51:01 amThat kind of black magic stuff can really waste a lot of time!

author: E-Design
author_rank: Regular Contributor
timestamp: November 16, 2020, 03:09:46 pm
content: It was suggested the OP RE-build his intermittent circuit off of the breadboard and put a scope on it.. not sure if he ever did.For these types of things: Simplify, Simplify, SimplifyIts the first thing I would do.

author: MarkR42
author_rank: Regular Contributor
timestamp: November 17, 2020, 12:38:04 pm
content: I think it's a good idea to prototype the circuit with breadboard and soic breakout boards, I've done that myself.One thing which did confuse me - some chips behave very badly if you don't put decoupling capacitors on them. Make sure there are suitable decoupling caps close to the chip on the breadboard, or perhaps add them to the breakout board if you can.I had a motor driver chip which would only run in one direction until I added a decoupling cap, then it was fine.

author: Alteregoxxx
author_rank: Contributor
timestamp: November 17, 2020, 03:02:02 pm
content: Finally back from some long checks for confirming stability of the results after having (probably) found the root cause for the muxes misbehaving.At the moment, after prolonged, in use, check of the chips, IT SEEMS that 5 out of the 6 muxes I had soldered on the adapters are correctly working, the only one not working seems to get really hot from time to time, hence it is, with a good amount o f probability, REALLY damaged.This result seems to lead to the conclusion, like a lot of you guys did firmly believe, that almost all the chips I did solder had not been damaged by my soldering: probably the only one that seemes really damaged, the one that gets hot, has been damaged by me, doing some improper connection, as a result of getting tired due to the great dose of frustration I was experiencing.Now, back to the root cause of the misbehaviour: the male dc power plug (a cable mount type one, like this :https://www.mouser.it/datasheet/2/670/pp_050b-1778524.pdf) of my power supply had the solder joint that join the ground wire to its crimp contact, slightly "cracked". This probably leaded to intermittent/high resistance ground path, hence causing the "getting me mad" problems.Now, how I've been so "lucky" to have just a couple of chips that, strangely, despite having that cracked solder joint, did work "good and stable", still remains a mistery to me...By the way, as I've already said, after reflowing that solder joint, no more strange and weird behaviour have manifested, hence it's enough for me....So, after having reflowed that cracked solder joint and checked for a day that the MUXs maddness was resolved, next day I switched to the opamps analysis.On the latter, the suggestions given by the user@2N3055were completely and absolutely spot on, the TSH82 opamps did really need very very special care for having them "working" on a breadboard: with careful (good ceramic caps) decoupling capacitors placement and avoiding even the smallest capacitive loading at the opamp outputs (interposing a 100 Ohm resistor between their outputs and the oscilloscope probe, in fact just the probe input capacitance of my oscilloscope , summed to the already very high stray/paraxite capacitance of the breadboard, was enough to having them badly oscillating) the opamps are stable enough for some very preliminay and rough tests: no way these opamps can work reliably and at their full potential on a breadboard, that's for sure. Shame on me for not having tought about their super large speed and bandwidth as a potential cause of my headaches.Nevertheless, the reason why I was not suspecting a misbehaviour caused by opamp instabilty, was because I couldn't see any oscillating signal on its outputs: I saw just a "wrong" dc value (compared to the DC value I was expecting to measure, I mean) that here and there went up, then down, then "stable" for 10-20 seconds, then again down, then up etc etc...but the reason I was not seeing the hidden instability oscillations is that I was using "only" 5-10MHz as sampling frquency on my oscilloscope (after all I was expecting a DC signal, no need for high sampling rate, right?) : the moment I rised it up to 50-100Mhz, all the infamous, bastard, evil instability oscillations have shown in all their glory. Shame on me again for such a big superficiality.Finally, I want to thank you guys all and the userSiwastajaand2N3055in particular, for all the precious hints, all very appreciated, no suggestion excluded: this is a very active and supportive community, thank you for your help!Have a really nice day!

author: 2N3055
author_rank: Super Contributor
timestamp: November 17, 2020, 03:12:51 pm
content: I'm really glad you found both problems..Take care!Sinisa

author: Siwastaja
author_rank: Super Contributor
timestamp: November 17, 2020, 06:37:09 pm
content: Wow, congratulations!Not surprised at the result. Hence the usual advice, simplify, rebuild. And: multiple separate causes!I could guess the one chip getting hot might be damaged by accidental shorting of outputs, or injecting voltage to some pins that arenotlatch-up tolerant before powering up. Happens easily if ground is breaking.

author: tooki
author_rank: Super Contributor
timestamp: November 18, 2020, 11:13:17 pm
content: Quote from: bson on November 15, 2020, 09:19:28 pmIndeed. The machined header pins are FAR better for breadboarding. (And those, too, need to be soldered in correctly: the thicker side gets soldered, the thinner side are the pins themselves.)

author: SilverSolder
author_rank: Super Contributor
timestamp: November 19, 2020, 02:17:03 am
content: Quote from: tooki on November 18, 2020, 11:13:17 pmI have never had an issue with the square header pins, maybe mine are thinner than average? I'm going to have to measure them now...

author: SilverSolder
author_rank: Super Contributor
timestamp: November 19, 2020, 07:27:30 pm
content: Quote from: tooki on November 18, 2020, 11:13:17 pmOK, so I just measured the square header pins that I use. They measure as 0.64mm from face to face.For comparison, #22 hook-up wire (recommended for breadboards) is 0.645mm in diameter.Coincidence? I think we should be told!

author: 2N3055
author_rank: Super Contributor
timestamp: November 19, 2020, 08:20:54 pm
content: Quote from: SilverSolder on November 19, 2020, 07:27:30 pmWire is then 0,645 mm max dimension, while square pin will be 0,912mm diagonally....If you shove it at an angle, you might damage contacts in a breadboard. Plus edges are sharp.With header pin connectors, connector layout forces proper direction... With individual pins, all bets are off...

author: exe
author_rank: Unknown
timestamp: November 19, 2020, 09:04:39 pm
content: Quote from: Alteregoxxx on November 17, 2020, 03:02:02 pmMany scopes have "peak detect" mode, helping with this issue.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 19, 2020, 10:19:36 pm
content: Quote from: 2N3055 on November 19, 2020, 08:20:54 pmThink about it... if there is more than 1 pin on the header.... how are you going to shove it in at an angle? Maybe this is what is causing the problems, not the pin size!

author: 2N3055
author_rank: Super Contributor
timestamp: November 19, 2020, 10:31:47 pm
content: Quote from: SilverSolder on November 19, 2020, 10:19:36 pmIsn't that what I just said...?

author: Howardlong
author_rank: Super Contributor
timestamp: November 19, 2020, 10:45:30 pm
content: Quote from: exe on November 19, 2020, 09:04:39 pmI think it's called Min/Max sample mode on the Analog Discovery. I love these ADs to bits, and the analog bandwidth even without BNC adapter is about 25MHz or so, the bandwidth in the specs isn't using a standard 3dB bandwidth measurement. Irrsepective, it's not great if your op amp has a 100MHz GBW product and it's mounted on solderless breadboard. I am quite the fan of solderless breadboarding, but also thanks to my own experiences of learnign the hard way I know when trouble's likely to brew.And of course W2AEW has a vid on this...

author: SilverSolder
author_rank: Super Contributor
timestamp: November 19, 2020, 10:56:19 pm
content: Quote from: 2N3055 on November 19, 2020, 10:31:47 pmI'm not sure what you are saying - surely nobody other than a complete n00b could be inept enough to try to force a header into a board at a 45 degree angle?The pin distance would be sqrt(2) too wide, it would take extreme force!

author: fourfathom
author_rank: Super Contributor
timestamp: November 20, 2020, 03:24:28 am
content: Quote from: SilverSolder on November 19, 2020, 10:56:19 pmSometimes 45 degrees works, like with my 3.5mm pitch terminal blocks. I can put a short one in at 45 deg and they fit in a 0.1" *solder* perfboard. I would never try this with a solderless breadboard -- the pins are too fat. Hey, I have a big bag of these terminal blocks, so I'm going to use them!

author: 2N3055
author_rank: Super Contributor
timestamp: November 20, 2020, 07:30:00 am
content: Quote from: SilverSolder on November 19, 2020, 10:56:19 pmSure. An nobody ever "plugged in" USB or micro USB ports upside down, or similar ..Of course they do.. Nooby thing to do, yes, but I w'e seen it all. Including pins in solderless breadboards. And guy didn't even use force. He simply heated pins with soldering iron...

author: Howardlong
author_rank: Super Contributor
timestamp: November 20, 2020, 10:36:40 am
content: FWIW, for device adapters and multi way interconnects on solderless breadboard, I very strongly recommend keeping a stock of turned pin headers rather than the more brutal square headers.While branded Harwin D01-992 series are possibly the epitome of header nirvana, they're horrendously expensive: you can find satisfactory turned pin alternatives reasonably easily, for example I keep a generous stock of these for general usehttps://www.amazon.co.uk/gp/product/B00FFY2OGY, leaving the Harwins for virgin unicorn eventualities on especially rainy days.Just make sure you mount them in the right way around, soldering the shorter end, and leaving the longer end to mate with the solderless breadboard: the shorter end typically isn't long enough to gain sufficient purchase into the solderless breadboard.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 20, 2020, 02:34:02 pm
content: Quote from: 2N3055 on November 20, 2020, 07:30:00 amCome on, @2N3055. I just tried to plug a header in at a 45 degree angle on a scrap breadboard here, and it is totally impossible if there are more than 2 pins, and very difficult with 2 pins.Bottom line, the risk of breaking your breadboard with a square header pin is negligible unless you are intentionally trying to break something, or so mechanically insensitive that you are probably breaking everything you touch anyway!Certainly there is no convincing reason for a "normal" electronics hobbyist or professional to worry about square header pins.

author: 2N3055
author_rank: Super Contributor
timestamp: November 20, 2020, 04:11:51 pm
content: You cannot if you have few connected together.. obviously..With individual wires, no problem...

author: SilverSolder
author_rank: Super Contributor
timestamp: November 20, 2020, 04:21:00 pm
content: Quote from: 2N3055 on November 20, 2020, 04:11:51 pmWe are talking about a header with square pins, for example like this, right? :

author: 2N3055
author_rank: Super Contributor
timestamp: November 20, 2020, 05:42:35 pm
content: No, these with square pins...

author: bson
author_rank: Unknown
timestamp: November 20, 2020, 05:57:59 pm
content: Quote from: SilverSolder on November 19, 2020, 02:17:03 amAlthough as pointed out they're the same dimension across as 22 awg copper wire. Still, they do damage breadboards... Not sure why. Could be the point is sharp, hard steel, and when pushing the long side in it goes all the way to the bottom and deforms the contact? All I know is I've ruined more than one nice 3M breadboard with them... I do have a supply of cheap small chinese knockoffs for destructive use like that though since sometimes it's simply too convenient not to. I also sometimes use the cheap stuff to hold things in alignment while soldering.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 20, 2020, 08:30:59 pm
content: Quote from: 2N3055 on November 20, 2020, 05:42:35 pmAh, premises, premises!Yes, I can see those being inserted wrong with square pins. I don't have any of those though, so I don't know how easy it is to do.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 20, 2020, 08:39:06 pm
content: Quote from: bson on November 20, 2020, 05:57:59 pmAlmost all of the connections I make on a breadboard use the square header pins - it is just super convenient to make little re-usable "legos" out of soldering SMD components onto 2-pin header strips, or make little reusable RC filters out of a 3 pin header strip. Time and space saver if you often use the same RC filter for whatever reason. Saves me keeping an inventory of through-hole parts just for breadboard use. Of course, I use the breadboard as an extra pair of hands when soldering these things together... it works very well for that!I have not managed to break a breadboard yet, maybe I'm just not trying hard enough!

author: Howardlong
author_rank: Super Contributor
timestamp: November 20, 2020, 09:46:54 pm
content: Quote from: SilverSolder on November 20, 2020, 08:39:06 pmOne problem with multi way square pins is that they become very stiff, making adapter boards difficult to insert and extract. You can get away with them for six or eight pin break outs, but much more they become a right royal PITA, which is why I strongly recommend using turned pin headers instead for pretty much all breakouts beyond a handful of pins.

author: SilverSolder
author_rank: Super Contributor
timestamp: November 20, 2020, 11:18:47 pm
content: Quote from: Howardlong on November 20, 2020, 09:46:54 pmThis kind of thing?

author: Howardlong
author_rank: Super Contributor
timestamp: November 21, 2020, 01:22:20 am
content: Quote from: SilverSolder on November 20, 2020, 11:18:47 pmYes.

author: tooki
author_rank: Super Contributor
timestamp: November 21, 2020, 10:05:55 pm
content: Quote from: 2N3055 on November 20, 2020, 05:42:35 pmThat’s not a header. A header means pins on a PCB.

author: tooki
author_rank: Super Contributor
timestamp: November 21, 2020, 10:09:05 pm
content: Quote from: SilverSolder on November 20, 2020, 08:30:59 pmThey go in readily at varying angles because they’re not truly square. They’re not round, either. They’re sheet metal rolled into a sort of U shape. But the sheet metal is so thin that it’s easily deformed away from its initial profile of a hollow squarish U. In a good quality breadboard, those pins will deform more easily than the breadboard contacts.

author: Wendy_Preston
author_rank: Contributor
timestamp: December 04, 2020, 10:44:00 am
content: Quote from: Howardlong on November 20, 2020, 10:36:40 amOK, that's a first - we do pride ourselves on quality (which may unfortunately sometimes translate to a pricetag not so suitable for the hobbyist market). But "header nirvana"!That's honestly made my day. Thank-you!

author: thinkfat
author_rank: Unknown
timestamp: December 04, 2020, 03:42:49 pm
content: Actually, I've used Harwin M20 and M50 series connectors in the past for hobby projects. They're expensive, yes, but not prohibitively expensive, even in single quantities via a distributor. For my hobby stuff I rarely need more than one or two at a time so cost isn't that big a factor.