LMZ14201: ADJ_NOPB

Hi Saleh,

Can you send a picture of the T&R for the part you are having issues with and also the top marking of the device?

Thanks,

Andrew

Hi Saleh,

I will check with quality.

Thanks,

Andrew

Hi Andrew 
thank you and can you please confirm if we can clean this part or no 

best regards 

Hi Salah,

I think it's ok. The top marking is pretty clear.

Thanks,

Andrew

Hi Andrew, thank you for the reply. If I understand correctly, there is no issue if we clean the PCB with the component on it. This is because he had more than one failure

Hi,

We are observing the 4th of July holiday. Please note that responses will be delayed.

Thanks,
Andrew

Hi Andrew
Happy holiday, no problem appreciate your  support 

Hi Salah,

Can you advise on the cleaning process? Does this involve high temperatures?

Thanks,

Andrew

Hi Andrew, I will get back to you with the process after consulting our PCB assembly supplier. I noticed that all the parts that failed (15 out of 50) had the same issue: a short between pins 3 and 4. The short remains on the component even after removing it from the PCB

Hi Andrew, 

Thank your for reply I will consult the document.

Hi andrew this is the clean process 
- Washing time: 32 minutes
- Washing temperature: 51 degrees Celsius or 125 degrees Fahrenheit
- Type of Zestron: High Precision Cleaning
- Drying: Manual with air blower
- Type of machine used: Aqueous Technologies

Hi Saleh,

What does high precision cleaning mean? Is it like a pressure washer?

Thanks,

Andrew

Hi Andrew , sorry for late reply 

Our PCB supplier has informed us that they do not control the pressure settings of their machinery. The Aqueous machine they use comes with preset pressure settings. Additionally, they have clarified that the high-precision cleaning process does not utilize high pressure

Hi Salah,

Based on the trouble that this part has with reflow temperature I'd say this part is sensitive (not just to cleaning).

What reflow profile are you using?

Thanks,
Andrew

Hi Andrew,

Our PCB supplier mentioned that they are following the profile recommended by Texas based on the application note. However, I cannot confirm this based on the email we received. The issue we're encountering is a short between pins 3 and 4 on the chip, even when it is removed from the PCB.

I have a question: does Texas test each batch of chips during fabrication, or do they conduct sample testing?

Thank you.

Hi Salah,

Thank you for your patience, we test the parts during fabrication on an automated test equipment.

Thanks,
Andrew

Hi Saleh,

See below from quality team:

The cleaning temperature and conditions don’t appear to be such that cause this issue. However, since customer is indicating that the issue started when they introduced the cleaning process, then perhaps it needs to be further looked at by customer. Some questions below:

• Did they test the failing board before cleaning process?
• Are they still seeing failures from the same lot, before or after cleaning?
• Have they tried units from any other lot with the cleaning process to see if they have similar failures?

If they still see failure even before cleaning, then they may want to submit a request to send a unit back to TI via customer return portal (TI web site) for analysis

thanks,

Andrew

Hi Andrew

• Did they test the failing board before the cleaning process?

  We are in the process of testing the boards. We've sent the procedure to our PCB assembler, but they are currently on vacation and will start testing next week.

• Are they still seeing failures from the same lot, before or after cleaning?

  We have not observed any failures from the same lot after cleaning. Out of a batch of 150 parts, we experienced 30 failures, but these issues did not persist post-cleaning.

• Have they tried units from any other lot with the cleaning process to see if they have similar failures?

  Yes, we have built some units from a different lot, applied the same cleaning process, and did not encounter the failure of shorting between pins 3 and 4.

Hi Saleh,

I apologize for the miscommunication. I misread your post. I just spoke with the quality guy. Let's wait on number 1's answer.

Also I have a question on #2. Based on your wording it sounds as though you are able to resolve the issue after cleaning the parts. Is this true?

salah-eddine dahel said:

we experienced 30 failures, but these issues did not persist post-cleaning.

Thanks,

Andrew

No, we have not resolved the issue on our side. What I mean is that from the batches we cleaned, not all PCBs failed; however, there were failures in each batch. In the first batch of 50 PCBs, we had 5 failures. In the next batch of 50 PCBs, we again experienced around 5 failures. In the final batch of 25 PCBs, there were 6 failures. All the PCBs had components from the same batch.

Hi Salah,

Is it possible to send a picture of the reel you used which is causing problematic boards?

Thanks,
Andrew

Hi Andrew,

I don't know if our supplier still has the reel with them. I will ask them when they open next week.

Thanks,
Salah

Hi Andrew this is the reply of our supplier 

The 102 units  were assembled with LMZ14201TZ-ADJ/NOPB – 10864 Texas Instruments date code 2133.

For this batch with date code 2133, we currently have a balance of 50 units on the production floor.

Thankyou I will check.

Thanks,

Andrew

Hi Salah,

Thank you for the lot information.

Can you return one of the problematic units on this portal?

http://www.ti.com/support-quality/resources/customer-returns.html

Thanks,

Andrew

Hi Andrew

Our supplier will remove the faulty part from the PCB, and we will handle the shipping.

Hi Andrew 

we shipped the part 

Hi Andrew,

I received the report from Texas and they confirmed it's a known issue. This is what the report says:

"The non-conforming behavior of the Customer Returned Device (CRD) has been attributed to a known fail mode previously identified for this product. The root cause is attributed to a known issue."

I will close this issue.

Best regards,