TMS320F28335: TMS320F28335 soldering issue

Jimmy,

         All devices are tested (during production) before they are shipped to customers. There are tests that check proper operation of all the I/O pins. I highly doubt if this is a quality issue. Likely happened during de-soldering. Desoldering surface-mount devices is pretty complicated and needs specialized equipment/skills.

Did customer identify the pin function of the missing ball(s)? Does it correspond with the problem they were seeing in their board?

Hi Hareesh,

Yes, customer found pin of 28335 without signal that de-soldering.

Customer just saw that the pin where the ball is missing is officially the place where there is no signal output.

Is there any correct SMD way about BGA?

Jimmy,

                If customer initially observed missing signals and upon device removal those were the exact balls that were missing, the problem cannot be attributed to de-soldering the device.

1. Can you please a photo of the top side of the devices?
2. Is this a new project or one that has been in production for a while?

Please see attached doc for helpful BGA tips.

BGA.pdf

Hi Hareesh,

Do you have soldered properly way?  about 28335 SMD way. thx 

It has been in production. pic provided later.

Jimmy WANG said:

Do you have soldered properly way?  about 28335 SMD way. thx 

www.ti.com/lit/SPRABY1 may be of help. Beyond that, I don’t have anything to offer. 

1. How long has this been in production?
2. What is the DPPM rate?

Hi Hareesh,

1. The product has been 3 years with production.

2. Total:2386 pcs  ok:1649  pcs   NG: 737 pcs

Customer always found  PIO0，PIO3，PIO6, PIO9 that  missing functions and ball of BGA at fail unit

Jimmy,

                That is a failure rate of almost 30%. That doesn’t sound right. You mention this has been in production for 3 years. Is this problem being observed only recently? Did anything (such as stencil, solder paste, reflow profile) change recently? This is a very popular device and we haven’t heard of this issue from any other customer. As explained before, there is a visual inspection step as part of the production process, where something like this should be caught.

Jimmy,

    Considering we are talking about 30% of the devices, is it possible to visually inspect a few dozen devices before they are mounted on the board to ascertain if these balls are missing? 

We have 100% AOI (automated optical inspection) on units as a final step prior to shipment from TI.  It’s not possible for units to ship with missing BGA balls.  This part ships in high-volume to many customers with no similar issues reported from others. 

Hi Hareesh,

The date code is 2130 because the customer's MCU has been stored for one and a half years before starting production

Before SMD, it will be baked at 125 degrees for 8 hours.

What do you think might cause the solder ball to drop?

You have not answered my following questions:

1. You mention this has been in production for 3 years. Is this problem being observed only recently?
2. Did anything (such as stencil, solder paste, reflow profile) change recently?
3. Considering we are talking about 30% of the devices, is it possible to visually inspect a few dozen devices before they are mounted on the board to ascertain if these balls are missing? 

And you are yet to provide a photo of the device.

Jimmy WANG said:

What do you think might cause the solder ball to drop?

I don't know. A device with missing balls would have failed our production tests and also the optical inspection. 

It is unexplainable why only these particular balls are missing after removal.  All balls would be missing at that point.  For any customer returns to TI, we have to re-ball units removed from PCB’s prior to test. Have you identified any missing balls prior to assembly?  Then we would have something to work with.  Once you have reflowed the device onto the board, and subsequently removed the devices, there is nothing left for us to work on. 

Hi Hareesh,

1. You mention this has been in production for 3 years. Is this problem being observed only recently?==> Yes
2. Did anything (such as stencil, solder paste, reflow profile) change recently?==> Customer feedback no change. 
3. Considering we are talking about 30% of the devices, is it possible to visually inspect a few dozen devices before they are mounted on the board to ascertain if these balls are missing? ==>Customer feedback no ball missing. 
5. I provide label as below