Unmarked SMD resistors - Page 1
Forum section: electronics / general

author: JohnnyP
author_rank: Regular Contributor
timestamp: September 18, 2020, 01:31:05 pm
content: I received a package of 0805 resistors from Mouser with no marking. I went online and found this document from Vishay:https://www.vishay.com/whatsnew/doc/ff_FastFacts_Marking-discontinuation.pdf"The marking of Vishay’s standard R-chips in the 0603 to 2512 case sizes — i.e. CRCW0603 – CRCW2512 with TCRof ± 200 ppm/K / 5 %, TCR of ± 100 ppm/K / 1 %, and TCR of ± 200 ppm/K / 1 %, 0.0 Ω — will be discontinued to improve the efficiency of the production process."Not good for those of us that do hand assembly.Are all brands phasing out marking?

author: asmi
author_rank: Super Contributor
timestamp: September 18, 2020, 02:04:55 pm
content: A lot of my boards have a ton of 0402, which are all unmarked, and I have no issues manually assembling them. You don't need any markings for hand assembly.

author: ataradov
author_rank: Super Contributor
timestamp: September 18, 2020, 05:30:40 pm
content: Capacitors are already unmarked anyway.This just makes it easier to assemble - now you don't need to think which side is up.

author: SilverSolder
author_rank: Super Contributor
timestamp: September 18, 2020, 06:07:58 pm
content: Quote from: ataradov on September 18, 2020, 05:30:40 pmI already didn't care!

author: PKTKS
author_rank: Super Contributor
timestamp: September 18, 2020, 06:25:01 pm
content: ... 2 cents..well I do care.I remember that classic movie BladeRunner (original)when the folk asked for the markings on piece ofsnake skin...readily the old woman found the markings w/a scope.Nothing can speak better for itselfElectronic parts are way more important thansnake skin and for the sake of responsible issues..The very same folks which care about using lead free.instead of leaded...well they don't care marking critical parts forreplacement and safety.There was a time were schematic was bundledinside the devices and parts were resposiblemarked..That time seems to be long gonePaul

author: ataradov
author_rank: Super Contributor
timestamp: September 18, 2020, 06:29:46 pm
content: Quote from: PKTKS on September 18, 2020, 06:25:01 pmWTF was that rant? What doers it have to do with resistor markings disappearing?

author: PKTKS
author_rank: Super Contributor
timestamp: September 18, 2020, 06:43:50 pm
content: Quote from: ataradov on September 18, 2020, 06:29:46 pmWhen you need to replace them...I do have bricked stuff just because I could notfound a suitable replacement.. for bad SMD parts.A hell of a waste of time and money.Anyone already pissed with that lack of markings already knowPaul

author: SilverSolder
author_rank: Super Contributor
timestamp: September 18, 2020, 07:25:40 pm
content: Quote from: PKTKS on September 18, 2020, 06:43:50 pmI agree about the missing documentation (and leaded solder!), but resistor values don't have to be marked on microscopic parts... as long as there is a schematic and a board layout, and as long as you have a pair of LCR tweezers, losing the resistor markings isn't really an issue to me.

author: JohnnyP
author_rank: Regular Contributor
timestamp: September 18, 2020, 07:48:22 pm
content: It looks like Panasonic is still marking 0402 and above. Refer to page 4 here:file:///Users/jp/Downloads/id_fixed-resistors_e_1.pdf

author: JohnnyP
author_rank: Regular Contributor
timestamp: September 18, 2020, 07:53:32 pm
content: Yes, I need a pair of LCR tweezers. I saw Dave doing a test and tear down on some for less than $80, I think?

author: SilverSolder
author_rank: Super Contributor
timestamp: September 18, 2020, 08:18:00 pm
content: Quote from: JohnnyP on September 18, 2020, 07:53:32 pmYes, that's a whole discussion in its own right. The most reasonably priced ones appear to be the Mastech MS8911. I've got a set of those coming, I like the fact that they can test with a low 100mV voltage to avoid exceeding silicon junction thresholds - so they can be used to measure components in-circuit.

author: asmi
author_rank: Super Contributor
timestamp: September 18, 2020, 08:20:05 pm
content: I never needed any of that. As long as you've got schematics, you don't need any markings.

author: SilverSolder
author_rank: Super Contributor
timestamp: September 18, 2020, 08:58:23 pm
content: Quote from: asmi on September 18, 2020, 08:20:05 pmIf you are talking about LCR tweezers, I think these are a reasonably new invention (at least at a reasonable cost) and may make things more convenient.

author: Rat_Patrol
author_rank: Frequent Contributor
timestamp: September 18, 2020, 10:00:41 pm
content: I run Panasonic resistors (have had excellent results, consistency, available, price, etc), they are still marked. Some resistors I have from other manufacturers are not marked.The only time it is a PITA for unmarked resistors is when you dump a bunch of components on a bench for hand assembly. My advise is to never do that anyway.If there is a silkscreen with component ID, I guess I just don't care either way.

author: tszaboo
author_rank: Super Contributor
timestamp: September 18, 2020, 10:31:22 pm
content: Quote from: ataradov on September 18, 2020, 05:30:40 pmI hope this was a joke. Ones side has the film, the other doesnt. Heat dissipation is different based on orientation.

author: Daixiwen
author_rank: Frequent Contributor
timestamp: September 22, 2020, 06:41:34 am
content: Just restrict yourself to only using 10k and 100n, and the problem is solved

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: September 22, 2020, 10:07:34 am
content: Quote from: PKTKS on September 18, 2020, 06:25:01 pm

author: SMTech
author_rank: Frequent Contributor
timestamp: September 22, 2020, 11:14:39 am
content: AOI systems can also use resistor markings for verification, when neither caps or resistors have distinguishing markings its another push towards SMT lines being fitted with component verification units that test parts to check machine loading. If you can build a complex assembly without losing track using unmarked 0402, well yay for you, I'm not going to make that claim because it would be a lie.We do have one client that uses the marking on a resistor to designate the version of the build so we have to buy a very specific brand to make sure we get the 3 digits they want just for that location.

author: ar__systems
author_rank: Frequent Contributor
timestamp: September 22, 2020, 11:48:43 am
content: Quote from: NANDBlog on September 18, 2020, 10:31:22 pmYour post is a joke. Heat dissipation? For caps? I mean yes it is a thing, but when was the last time you sized a cap for heat dissipation?Also "one side has film" is not how MLCC are built.For resistors majority of heat goes through solder joints anyway, so...

author: free_electron
author_rank: Super Contributor
timestamp: September 22, 2020, 12:23:13 pm
content: Quote from: ataradov on September 18, 2020, 05:30:40 pmNOT TRUE. The electrode on top is different from the electrode on the bottom !

author: Kleinstein
author_rank: Super Contributor
timestamp: September 22, 2020, 01:52:06 pm
content: Usually there is no big deal in soldering the resistors with the other side up. It may protect the numbering from getting damagedIn RF applications it can make a difference to reduce the inductance. Cleaning could be more stress to the film side closer to the board and trapping some fluid thereIt is convenient to have the numbering on hand soldered circuits, so one has it easier to check if there was a misplaced resistors. So one needs to be more careful if they all look the same. In the beginning it would be only a few values with no markings and the old stock still marked. The higher grades still seem to be marked.For 0.5 cent resistors the marking can be a significant part of the costs if there are some looking for the last percent cost savings.There is no need to get to 100 n and 10 K only - there are still different sizes. capacitors can also be different color usually more brown with X7R and more white with the better C0G ones.

author: NorthGuy
author_rank: Super Contributor
timestamp: September 22, 2020, 01:53:19 pm
content: I like the markings. When I do prototypes, I can easily check that I soldered correct resistors at correct places. Measuring resistance in-circuit isn't always possible.

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 22, 2020, 02:32:24 pm
content: long live capitalism!!!they cut costs and eliminate after-market repairing with one bullet.some resistors values are critical.they should be forced to give you the schematics in this case.hope they die eaten by a giant werewolf

author: Kjelt
author_rank: Super Contributor
timestamp: September 22, 2020, 02:44:37 pm
content: Just a big nuisance if you order a sample package of resistors, 100 of each value and you have to remeasure each strip for the correct value.Repairmost resistors that die, are unreadable anyway, browned out hole for the chimney the magic smoke escaped from.Reverse engineering yes, now you really have to desolder the resistors and measure to be sure.

author: TimFox
author_rank: Super Contributor
timestamp: September 22, 2020, 03:03:21 pm
content: I remember when we had a strange problem in the field, with a large set of SMT boards in an array. Some of them were responding differently with a dynamic situation (not at liberty to discuss details). It turns out that the "odd" boards were correct. Somehow, 1 nF and 10 pF capacitors (both values were on the board) had been interchanged during board stuffing (same case size and color, but SMT capacitors are almost never marked). Luckily, there were a couple of the boards from the same lot back at our lab, and a tweezer measurement verified the problem.

author: SMTech
author_rank: Frequent Contributor
timestamp: September 22, 2020, 07:16:48 pm
content: @TimFox There isn't a foolproof way yet of 100% avoiding a machine load error and switching 2 parts that are used on a build is one of the easiest ones to make.

author: TimFox
author_rank: Super Contributor
timestamp: September 22, 2020, 07:30:46 pm
content: Of course. I was just commenting on how unmarked parts make troubleshooting difficult.

author: SilverSolder
author_rank: Super Contributor
timestamp: September 22, 2020, 08:49:51 pm
content: I guess the main thing is to be aware that it can happen, and make sure there are fresh batteries in your LCR tweezers?

author: TimFox
author_rank: Super Contributor
timestamp: September 22, 2020, 09:23:33 pm
content: I am now.

author: tszaboo
author_rank: Super Contributor
timestamp: September 23, 2020, 11:40:23 am
content: Quote from: ar__systems on September 22, 2020, 11:48:43 amThe topic is about resistors.

author: ar__systems
author_rank: Frequent Contributor
timestamp: September 23, 2020, 12:24:41 pm
content: Quote from: NANDBlog on September 23, 2020, 11:40:23 amAnd you replied to the comment about caps. Anyway, even for resistors, your comments is still invalid. RF is probably the only area where orientation of a resistor would matter.FYI small resistors and caps are already being supplied in bulk (without tape). Not a problem.

author: SilverSolder
author_rank: Super Contributor
timestamp: September 23, 2020, 02:27:18 pm
content: Quote from: SMTech on September 22, 2020, 11:14:39 amThat's super clever, especially if the micro reads the resistor value to get the version of the board too?

author: tszaboo
author_rank: Super Contributor
timestamp: September 23, 2020, 02:36:12 pm
content: Quote from: ar__systems on September 23, 2020, 12:24:41 pmYes, I'm wrong and you are right. Now here is a cat wearing a hat for you to celebrate your glorious victory in a pointless internet discussion.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 01, 2020, 11:06:07 pm
content: I once did factory repairs of stuff that failed in the field, and we had a convention to put all resistors we replaced upside down so if a product ever came back for a 2nd time it would be easily recognizable.Long live the SMT tweezers.I Like my Mastech MS8910, even though you need to tweak it's beaks to make them fit properly.

author: Smokey
author_rank: Super Contributor
timestamp: March 04, 2024, 07:16:47 am
content: When hand populating boards, does anyone just take 0402 (or any unmarked) resistors and install them however they fell out of the cut tape with some upside down (black side down on the board)? For some reason I feel like I need to flip them all black side up and install them that way even through there is no value marking on either side. Sometimes it take a few tries to flip them over with the tweezers, but I still feel like I need to do it. Am I the only one that has this particular crazy?