What is the effect of wave soldering on the data retention of F-RAM?
There are three aspects to be considered, each leading to the next.
- Data retention through soldering:
The Cypress F-RAM data retention specification is applicable to data written into F-RAM within the specified temperature ranges, including write temperature, storage temperature, and read temperature. Retention of the data written in F-RAM pre-soldering is not specified because the soldering temperature is out of these temperature ranges.
- Retention time of data surviving soldering:
Because the soldering temperature is beyond the specified temperature ranges for write, read, and storage, Cypress doesn’t specify the retention time of those data that survives soldering. Rewriting this data post soldering will provide full retention life-time.
- Retention time of post-soldering data:
Post-soldering data is the data (regardless of 1 or 0) in any bit if accessed after soldering (regardless of writing or reading). The retention specification is applicable to all post-soldering data cumulatively. The two cases stated earlier (data retention through soldering and retention time of data surviving soldering) do not change the data retention specifications. Thus, Cypress specifies only the data retention time of post-soldering data.