# Date code in components marking

In some datasheet (two example in links below) I see only this information, about production date, in marking code explanation:

Date code (A : 1997.1)


If there was a further value I could think per induction but only with this information I can't figure out how to interpret the letters.

My capacitor (Matsuo type 553) have the second row: 63VM. The "63V" means rating 63V but the M what date mean? Maybe it is one date among 1998.1, 2000.3, 2002.5, 2004.7, 2006.9, 2008.11, 2011.1, 2013.3 and so on?
Or there is another way to count?

This is what say the datasheet:

(from: NCC-Matsuo metallized pet film capacitor - My capacitor)

And there it's another example:

(from: Jaro Components Tantalum Cap)

• Unless it is specified otherwise one would assume an increment of one year Jun 10 '16 at 10:38
• Thanks @PlasmaHH, often this is true, but in the datasheet is specified the month (1997.1). ...or the "one" is the week, like EIA-476-A? This make me confused. P.S: Thanks JRE for subject correction. Jun 10 '16 at 10:45
• For the capacitors letters usually have nothing to do with production date. It's a marking of tolerance, M stands for +/-20%. Jun 10 '16 at 16:42
• @lustful-rat, this isn't the case; I know capacitor code, my capacitor has 104J as value (and J is the tolerance) but in datasheet is mentioned date code as in the original question. You must see my first link to see what I say. Jun 10 '16 at 17:11

The Matsuo date code is explained in more detail in their other datasheets, such as p. 2 of the Matsuo Tantalum Solid Electrolytic Capacitors datasheet.

The codes repeat every 4 years:

The 12 uppercase letters A through M (minus "I") represent the 12 months Jan through December for one of the years 1997, 2001, 2005, 2009, 2013, 2017, ...

The 12 uppercase letters N through Z (minus "O") represent the 12 months Jan through December for one of the years 1998, 2002, 2006, 2010, 2014, 2018, ...

The 12 lowercase letters a through m (minus "i") represent the 12 months Jan through December for one of the years 1999, 2003, 2007, 2011, 2015, 2019, ...

The 12 lowercase letters n through z (minus "o") represent the 12 months Jan through December for one of the years 2000, 2004, 2008, 2012, 2016, 2020, ...

The capacitor you have with date code "M" was apparently manufactured in December in one of the years 1997, 2001, 2005, 2009, or 2013. (Since you had it in your hands June 2016 we can rule out any later years).

The Jaro date code looks like it might be exactly the same as the Matsuo date code.

• Thanks. I searched online but I don't found this datasheet. I tried to edit your reply, to add table and standard info and accept it, but my edit was rejected telling me to post this as answer. :-( I'll upvote your answer. Jul 12 '16 at 15:26

This coding standard is defined according to Japanese Industrial Standard JIS 5101, table 12 (as stated in the datasheet linked by davidcary) and in the Corresponding International Standards IEC 60384-1:2008 that refers, for the coding method, to IEC-60062, section 6.3.1 – Four-year cycle (small components, SM and THM only).

IEC-60062: Table 12 – One-character code – 4-year cycle

N.B.: The letters "O","o", "I" and "i" are omitted to avoid ambiguity. For the same reason, IEC-60062 stated that:

If there is a possibility that a single lower-case letter could be read as an upper-case letter, for example, v for V, the lower-case letter could be marked with a cross bar above it.

### Example (from the Original Question)

The capacitor Matsuo 553 with date code "M" was manufactured in December in one of the years 1997, 2001, 2005, 2009, or 2013. (I know the PCB came from '90, then the year is 1997).

The Jaro date code looks like it might be exactly the same as the Matsuo date code.

(Thanks to davidcary)

I think the "M" is not a data code but a failure rate of 1%/1000hrs. It's on the data sheet. Could possibly be an error in the translation.

I assume you do not have the original bag/packaging the cap arrived in? The packaging usually tells you what the date of manufacture was.

• Thanks for trying but this isn't the correct answer. The "code M" means that "Failure rate level code", i.e. failure rate level as encoded in the catalog number, is represented by letter M (at fourth position). See the table at end of datasheet; all the capacitors are numbered as 553 *M* 5002 .... As corroboration, you can see here, in Matsuo's capacitor type 204, that there's two differents code for failure rate, M and N, and thus catalog numbers are, for example, 204 *X* 3151 ... ,where X will be M or N (see note ¹). Jun 29 '16 at 12:55