We captured some failed boards with the “Spare Parts final” failure step on 15235 model at FT.
1.1. Device Name:IC,FPGAxEP4CGX50DF27I7N SMCBGA
1.2. Full Part Number[Jimmy Peng] : EP4CGX50DF27I7N
1.3. Date code[Jimmy Peng] :2013
1.4. Lot Number[Jimmy Peng] :3P9GE0G00
1.5. Trace Code[Jimmy Peng] :S014AK59
1.6. Distributor name:[Jimmy Peng] :Arrow
[RR: in user mode]
[RR:20 pcs out of 100 pcs]
[RR: Firstly: The failure occurs in FT station and test program indicates that no packet received from DUT. And the test principle of FT station is the signal goes into #1 optical, and via #2,3 and finally goes out from #4 optical port of DUT. So FT station only test the series loop signal. Also the LED are intermittent blinking which all LED light on means communication is ok or else miss the communication. Pls see below picture.
Secondly, all boards passed FCT station. But the FCT is bit different from FT station for this traffic test which this board contains 4 optical ports and the last 2 test items are traffic test which test principle is the signal goes into #1 optical port and goes out from #2 optical port. (#1 and #2 optical port connects with Smartbit test equipment #1 port). And the other signal goes into #3 optical port and goes out from #4 optical port(#3 and #4 optical port connects with Smartbit test equipment #2 port). So FCT station contains 2 groups signals test.]
[RR: It happened in final test station (FT station). The test program shows the error that no packet received from DUT]
[RR: Yes , I swapped. And the failure followed the chip but not the board.]
[RR: It comes from my side to dig root cause.]
[RR: Already mass run production]
[RR: 1. checked the related components no soldering issue and cosmetic issue no found.
2.Take 3pcs failed boards to x-ray, no open or short issue found.
3.Reheat the failed U18 BGAs, test still failed.
4.Re-mounted the failed U18 BGAs ,test still failed.
5.Remove the failed u18 and remount it in the passed board, the fail step and information is same.
Suspected the U18 BGA working abnormal. After replaced the suspect BGAs , the boards passed test process. So confirm that the fail symptom will follow the suspect BGAs]
[RR: NA. There is no spec for final test which just no packet received from DUT.]