SMD part marking - why? - Page 1
Forum section: electronics / general

author: fzabkar
author_rank: Super Contributor
timestamp: July 03, 2024, 05:23:24 pm
content: The image says it all.LM10507, 3x Programmable Buck + 2.5V 250mA LDO Power Management IC (PMIC), marking V087, DSBGA (34):http://www.ti.com/lit/ds/symlink/lm10507.pdf

author: Siwastaja
author_rank: Super Contributor
timestamp: July 03, 2024, 05:34:31 pm
content: The question is loaded.The reason could be anything, possibly something unimportant. The key takeaway is, there is not much role for complete markings in modern days, because SMD parts are automatically picked and placed from reels; human placement is not used, so part identification is made onreel level: reel labeling is important, not part laser marking. Also products are not repaired by looking at what components happen to be used and buying replacements; ICs rarely fail anyway, and if they do, complete PCB assemblies are replaced. In rare cases where component level repair is being done, manufacturers assume that schematics and layout pictures are available to repair personnel. In any case, de- and resoldering such parts is specialized and difficult work anyway.Someform of marking, which varies between ICs, is useful for automatic optical inspection to catch differences between a board and a reference golden standard board, but fuller part number does not add much value. Also any text makes it easy to visually confirm the orientation.Many parts are available in both very tiny and larger packages, so it would be logical to use same typographical choices for both.None of these are reasons not to add fuller marking, but are reasons why it isn't very important. So instead of explaining why not exactly, I'm pointing out they could ask you a counter question, why should they?

author: thm_w
author_rank: Super Contributor
timestamp: July 03, 2024, 08:44:33 pm
content: Multiple reasons:- LM means the part was originally designed by National Semiconductor (= linear monolithic), so they would have had their own marking system that might not match up with TI's.- All of the LM105xx parts follow the same marking scheme, "Vnnn". So maybe some initial part was too small to fit the full part number, and they started off with that shorter code, and just continued using it for the whole lineup.You can read more here:https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/151/devicemarkingconventions.pdfhttps://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/2004JUN17_5F00_DA_5F00_ICP_5F00_AN.PDF

author: EPAIII
author_rank: Super Contributor
timestamp: July 04, 2024, 06:16:55 am
content: And yet, some of us still want to use the chips in small numbers, even onzies. And want to do repairs at the component level.Ever been stuck with a mission essential piece of equipment that costs tens or even hundreds of thousands of dollars and it has failed. And then when you call the OEM, they just say that support ended for that item. They aren't even sure that the schematics and other drawings haven't gone to the incinerator, but they will look when they get a chance. So for want of a $1 chip you will need to buy a new, multi-thousand dollar item?Really, have you ever been THERE? I HAVE, and it is NO FUN. It happens all too often.I know that marking the ID on the chips is no guarantee that they will be available when that happens. But it is also no guarantee that they won't.And as the chips are getting smaller, there are people out there (obviously not in your experience) who develop ways to handle the job of replacing them.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 04, 2024, 06:46:55 am
content: More marking = a few more milliseconds of laser time on the production line. Time is money.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 04, 2024, 12:31:09 pm
content: Quote from: EPAIII on July 04, 2024, 06:16:55 amMe included, but I don't need part markings for that. I store the parts in the supplier packages I bought them in (which have full part number, description and supplier order code printed), it's not like I empty all the packages into one large drawer and mix them up. Your mileage may vary.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: July 04, 2024, 04:55:32 pm
content: Maybe so, but the parts on the defective board I'm trying to repair are not in their supplier packages. I would say the approach makes sense for parts where just replacing them in a repair scenario may not be sufficient (micros with onboard Flash, for example) but these are often the ones with clear markings.

author: fzabkar
author_rank: Super Contributor
timestamp: July 04, 2024, 06:18:50 pm
content: Quote from: Siwastaja on July 04, 2024, 12:31:09 pmIt seems to me that you are out of touch with what goes on in the repair world. Supplier packages? The whole point of sensible, logical part markings is so that we can identify the IC after it has left its package.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 04, 2024, 06:21:05 pm
content: Ask them. Don't be surprised if there's no answer though... it's just not important.Tim