We are using CY14E256LA-SZ45XI NVSRAM as a replacement for STK15C88-NF45I SIMTEK which got obsolete. We did not have any problem with prototypes but now for the TRUN that we made 30 pcs 11 pcs have failed due to NVRAM corruption. The MCU cannot boot. The PCBA vendor is usinghttps://www.xeltek.com/production-programmers/superpro-7500/SUPERPRO 7500 to program the NVRAMs prior to assembly process.
We had a test on 20 NVRAM chips so we programmed all of them and then read the content and all were okay then all of them have been placed on a board and went through reflow and then we read the content back. the content 5 out of 20 have changed (corrupted). The reflow profile is very close to cypress recommendation (http://www.cypress.com/documentation/other-resources/cypress-reflow-profile ) the peak temperature is 240 degree C and the whole process is getting about 4.5 min (It has been attached here).
Is anybody have any suggestion that can help.