Counterfeit IC's? - Page 1
Forum section: electronics / general

author: invzim
author_rank: Contributor
timestamp: January 20, 2020, 12:10:39 am
content: Any experienced eyes here that can spot a counterfeit? I've had 100 boards produced, with PCB, sourcing of components and assembly. One them had issues and I traced the error back to one of these - not sure which, as I replaced them both at the same time. I've used this company about 7 times before with no issues, so it's a little strange.Edit: link to pictures,https://imgur.com/a/YG4HRf3Things I found suspicious- different markings on bottom of chip, if they were sourced from a reputable source I presume they would have the same markings- looks like one of them are 'sanded'

author: Yansi
author_rank: Super Contributor
timestamp: January 20, 2020, 12:18:26 am
content: You better tell us what electrical malfunction you have found.Style of the bottom letters looks identical, and their meaning is meaningless for the purpose of identifying a fake. The code may as well be for example a code of an encapsulation mold, etc...

author: invzim
author_rank: Contributor
timestamp: January 20, 2020, 12:24:21 am
content: The IC is an analog switch, the fault was degradation with either higher higher resistance on one channel, or leakage to GND.

author: wraper
author_rank: Unknown
timestamp: January 20, 2020, 12:28:22 am
content: Might be ESD damage.

author: invzim
author_rank: Contributor
timestamp: January 20, 2020, 12:33:30 am
content: ..or moisture/lack of baking. So the different appearance of the same IC from the same PCB is normal and not indicative of anything fishy?

author: wraper
author_rank: Unknown
timestamp: January 20, 2020, 12:35:11 am
content: Quote from: invzim on January 20, 2020, 12:10:39 amThat depends on IC. If it also was different laser marking on the bottom it would be suspicious. For example laser marked date code on top and bottom of Atmel MCU should match. In this particular case IMHO Yansi is right. This code is embedded during molding process. Thus not something you could easily change every batch.QuoteIMHO it isn't.

author: wraper
author_rank: Unknown
timestamp: January 20, 2020, 12:38:46 am
content: Quote from: invzim on January 20, 2020, 12:33:30 amThey look the same on the bottom photo. Maybe surface is a bit contaminated. Or depending on particular mold surface may be a bit more rough or glossy. Thus under different observing/lighting angle may look a bit different.

author: invzim
author_rank: Contributor
timestamp: January 20, 2020, 12:42:28 am
content: Yeah, it's the top finish/marking/texture I find strange that is different - I replaced them with parts from digi-key, and they look identical. If they are from different batches/packaged in different factories it may explain it.Got 25 more boards to QA, and I'll pay extra close attention to this on the rest.

author: wraper
author_rank: Unknown
timestamp: January 20, 2020, 12:44:04 am
content: Quote from: invzim on January 20, 2020, 12:33:30 amTSSOP package according to datasheet is MSL level 1 thus does not require baking.

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: January 20, 2020, 12:47:05 am
content: Couple of questions:1. Who supplied the original IC's? If it's someone reputable like DigiKey/Elemenr14/Mouser then you are very unlikely to run into counterfeit components2. Did replacing the IC with one from DigiKey help, or could this be a circuit issue?Also CTI & SMT have a couple of really good presentations on how to spot counterfeit components:https://www.cti-us.com/pdf/CCAP-101InspectExamplesA6.pdfhttps://www.smta.org/chapters/files/Uppermidwest_VendorExpo_SMTAI-Upper-Midwest-Presentation-06-09-11.pdf

author: wraper
author_rank: Unknown
timestamp: January 20, 2020, 12:48:47 am
content: Quote from: invzim on January 20, 2020, 12:42:28 amAs example I use AD8293 in sot23-8. Even in the same tape some have perfectly flat surface, some concave. Some are perfectly glossy, some like a bit sanded. Noticed this in every batch from every reputable supplier I ever ordered. In your case surface difference is minuscule and packaging is exactly the same.

author: wraper
author_rank: Unknown
timestamp: January 20, 2020, 12:54:58 am
content: I just grabbed a random tube of ICs from TI in TSSOP package. First 3 characters are the same, 3 last characters are different. Another tube of different ICs has the same 3 character difference.

author: invzim
author_rank: Contributor
timestamp: January 20, 2020, 01:15:03 am
content: Quote from: ANTALIFE on January 20, 2020, 12:47:05 amAssembly house did the sourcing, China, they say it's reputable and that they've used them forever - but didn't disclose the name. This is just one board out of a 100, others so far have worked fine (in this respect - but that's another story), when replaced with parts from digi-key, they behave like they should.Thanks for the presentations, much better than the ones google served me!

author: forrestc
author_rank: Unknown
timestamp: January 20, 2020, 01:24:06 am
content: Quote from: invzim on January 20, 2020, 12:33:30 amI can't tell if this is a TSSOP or just a SSOP from the pictures. FYI the TS5V330CPWR currently has a MSL rating of level 1 (unlimited) for the tssop and level 2 (1 year) for the SSOP package.On the bottom markings: These allow TI to trace this back to a specific mold die and the exact cavity in the mold. Apparently this decodes to mold ID 05, Chase C, Positions 98 and 00. This is a standard TI marking.On the top markings: starting with the TI, this appears to be a standard 7 Digit date code, 6BMA9HD. This means that this is likely and old part, manufactured in 2016, November (see MSL issue above if this is a SSOP). MA9H is the lot code. D is the Site Code.G4 on the bottom row typically means lead free.In my opinion these are both from the same batch, and seem to be from TI. I'd be a little worried about the date code, but some parts move so slowly that a 3 year old part isn't unheard of.