This case study is intended to assist the reader in identifying HDD IC part markings. Our example will be a Seagate ST313021A HDD.
Seagate Barracuda 7200.10 ST3320620A hires PCB photos:
The attachments show the MCU, motor controller, and read channel ICs:
The IC manufacturers are identified by their logos - STMicroelectronics and Infineon Technologies. Infineon was created when Siemens spun off its semiconductor division into a new company, hence the Siemens copyright notice.
The next most obvious markings are the countries of manufacture (Taiwan, France, Malaysia). Often one will find that US HDD manufacturers will source their ICs from US or European chip makers whereas the Japanese usually source from other Japanese companies, often their own.
ICs will generally have date codes and/or batch codes. Most often these will be in YWW or YYWW (Year / Week) format. The photos show that the ICs were manufactured during weeks 05 and 07 of 2000.
The Infineon MCU has a Siemens/Infineon part number of MAB-M3005-8D. The "MAB" prefix is and was used by Siemens/Infineon and Philips/NXP for their range of microcontrollers.
For example, a search for "MAB* microcontroller Siemens" at http://www.datasheetarchive.com will produce numerous hits such as "MAB8049" which is an old 8-bit microcontroller.
All three ICs appear to have Seagate internal part numbers:
"ATLANTIS" appears to be the code name for the MCU, probably Seagate's.
The other markings could be batch codes or serial numbers.
The following examples (from Google Images) show that the "EC" marking code is ordered alphanumerically by date:
Code: Select all
This would suggest that the marking may be a serial number.
The markings on the motor controller also appear to be ordered by date in some way. However the variation seems to be too small for a serial number. Instead I suspect that the first 5 characters may reflect a batch code. I believe the same would apply for the read channel IC.
- 1A81S 9929