Walsin MLCC Customized Part: 432 of 24,026 Rows Are Flagged and the Part Number Does Not Say So

We counted the Remark column across all 24,026 rows of Walsin’s combined MLCC export. 432 rows, 1.8%, are flagged as a customized product or a customize part number. Nothing in the twelve-character part number marks a walsin mlcc customized part, so a buyer selecting from the export can land on one without knowing.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 parametric export files published by Walsin Technology (Walsin) and 28 Walsin datasheets, 451 pages, sent on request. This post is measured from 00_ALL_MLCC_parts_combined.xlsx, cross-checked against the 26 MLCC approval sheets indexed in INDEX_MLCC_series.csv. Every part number below is real and appears in that export. Every count is of part numbers, not pieces.

How many Walsin MLCC rows are flagged as customized?

432 of 24,026. We read every non-empty value in the Remark column and found it filled on 435 rows holding 8 distinct strings. 420 of those rows say the part is a customized product and to contact a local representative. A further 12 read “It is for customize part no.” The remaining 3 read a single asterisk with nothing to explain it. So the column is populated on 1.8% of the file and that 1.8% is the only place this information appears.

Remark value, as it appears	Rows
Customized product. then a line break, then Please contact WTC local representative.	311
Customized product.Please contact WTC local representative. — no space after the stop	45
The same sentence wrapped in literal double quotes	41
Customized product. Please contact WTC local representative. — the clean form	22
It is for customize part no.	11
Customized product — no second sentence at all	1
It is for customize part no — no full stop	1
*	3

We have not seen this counted anywhere. The three asterisk rows are all 1808 parts in the S2 safety series, and two of them are the same part number, S242N390J502, appearing twice on identical data. An asterisk is a footnote marker with no footnote in the file.

How many different ways is the same sentence spelled?

Five for one sentence and two for the other. We grouped the 420 customized-product rows and the variation is entirely punctuation and whitespace: an embedded newline on 311, a missing space after the full stop on 45, literal quotation marks around the whole string on 41, the clean sentence on 22, and the truncated Customized product with no instruction on 1.

This is not cosmetic. A buyer who filters a BOM against this column with an exact-match rule on the clean sentence catches 22 of 420 rows and misses 398. A rule that splits on the full stop breaks differently on the 45 rows with no space. The newline inside a cell on 311 rows is the worst of them, because it survives into a CSV as a quoted multi-line field and will split a naive import into two rows. The 12 “customize part no.” rows would not be caught by any of those filters, because they do not contain the word “product”.

Which series and case sizes are affected?

Ten of the sixteen series, concentrated in two case sizes. We counted the 432 rows by series: Middle to High Voltage holds 236, General Purpose 132, the SH soft termination series 36, the 1825/2220/2225 big sizes 10, the AEC-Q200 qualified MT series 5, the S2 safety series 4, MG 3, the HH high Q low ESR series 3, the automotive soft-term ST series 2 and the low profile TT series 1.

Case size	Flagged rows	Share of the 432
1206	194	44.9%
0805	129	29.9%
1210	48	11.1%
1808	19	4.4%
1812	15	3.5%
0603	9	2.1%
0402	8	1.9%
2220	5	1.2%
1825	3	0.7%
2225	2	0.5%

1206 and 0805 together are 323 of 432, which is 74.8%. By dielectric the split is X7R 288, NP0 119, X5R 17, X6S 6 and Y5V 2. The concentration follows the Middle to High Voltage series, where 1206 and 0805 are the working case sizes for 200 V to 4 kV parts — the Walsin approval sheet for that series, 04_Middle_and_High_Voltage.pdf, covers 0402 to 1812 sizes across 13 pages and is dated September 2026.

Can you tell from the part number that a part is customized?

No, and the reason is sharper than it first looks. We counted 411 distinct part numbers across the 432 flagged rows, then checked each one against the rest of the file. 373 of the 411 also appear on an unflagged row of the same export. Only 38 are flagged and nowhere else. So for 373 part numbers, the same twelve characters are simultaneously a catalogue part and a customized part, depending on which row you read.

The export holds 23,601 distinct part numbers across 24,026 rows, so 425 rows are duplicates by part number — and 373 of those duplicates are exactly this flagged-and-unflagged pairing. Nearly all the duplication in Walsin’s MLCC export is this one phenomenon.

Part number	Series, size, dielectric	Flagged row thickness	Unflagged row thickness	Match / mismatch between the two rows
MT21B104K500	MT, 0805 X7R 100 nF 50 Vdc	1.25±0.10	0.80±0.10	Match on all eight electrical fields; mismatch — 0.45 mm taller, and only the tall one is flagged
MG21B102K500	MG, 0805 X7R 1000 pF 50 Vdc	0.60±0.10	0.80±0.10	Match on all eight electrical fields; mismatch — 0.20 mm thinner, and only the thin one is flagged
0402X104K500	General Purpose, 0402 X5R 100 nF 50 Vdc	0.50±0.20	0.50±0.05	Match on nominal thickness; mismatch — the tolerance is 4x wider on the flagged row
0402S474K6R3	General Purpose, 0402 X6S 470 nF 6.3 Vdc	0.50±0.20	0.50±0.05	Match on nominal thickness; mismatch — 4x wider tolerance on the flagged row
0603X225K160	General Purpose, 0603 X5R 2200 nF 16 Vdc	0.80+0.15/-0.10	0.80+0.15/-0.10	Match on every field we hold — and one row is flagged, the other is not
1210B334K401	Middle to High Voltage, 1210 X7R 330 nF 400 Vdc	2.50±0.30	2.50±0.30	Match on every field we hold — and one row is flagged, the other is not
MT18B224K100	MT, 0603 X7R 220 nF 10 Vdc	0.80+0.15/-0.10	no unflagged row in the export	Mismatch — one of the 38 that exist only as a flagged row

We will not tell you a part is equivalent to another. We will show you where it differs — and on two of those seven rows we have to tell you that nothing in the data differs at all.

What is the difference between the flagged row and its twin?

The thickness, on 361 of the 373. We compared all nine specification fields on each pair. The T column differs on every one of the 361: alone on 271 pairs, together with L and W on 75, with W on 11, with L on 1, with the tolerance on 2 and with the rated voltage on 1. On the remaining 12 pairs nothing differs in any field we hold.

Those 12 are not a random residue. They are exactly the 12 rows carrying “It is for customize part no.” — 0603S475K4R0, 0603S475K6R3, 0603S475M4R0, 0603S475M6R3, 0603X225K160, 0603X225K250, 0603X225M160, 0603X225M250, 1210B334K401, 1210B334K451, 1210B334M401 and 1210B334M451. Each is a byte-identical duplicate of a standard row with a different remark attached.

So the practical reading is this: on 361 part numbers the flag marks a non-standard height, which is a real engineering difference your board clearance cares about. On 12 part numbers the flag marks nothing we can see, and only Walsin can say what. The MT automotive datasheet we hold, 11_Automotive_MT.pdf, carries a Size Thickness (mm)/Symbol table on page 13 of 29, and the soft-termination datasheet 19_Soft_Term_SH.pdf carries the same table on page 18 of 27 — so the height question is answerable from a document even where the export leaves two rows arguing. For why thickness is the field a cross tool keeps handing back to you, see thickness and tolerance, the two fields every cross tool asks you to check. For the series split behind the flagged MT and MG rows, see AEC-Q200 MLCC: MT vs MG series.

Is a customized-product remark the same as a discontinuation notice?

No, and conflating the two is the error to avoid. A customized-product remark says the part is made to a specific arrangement rather than held as a standard catalogue line. It says nothing about whether a standard part has been withdrawn. We hold no affected-part list for any manufacturer, we will not assert that any specific part is discontinued or obsolete, and nothing in these 432 rows supports such a claim.

What the remark does carry is a commercial consequence worth planning around: 373 of the 411 flagged part numbers have an unflagged twin in the same export, which means in most cases there is a standard-thickness version of the same electrical part available under the identical part number. The 38 that do not include MT18B224K100 and MT31B474K160 in the AEC-Q200 compliant MT series, ST21B103K500 and ST21B104K500 in the automotive soft-term ST series, three SH soft-termination parts including SH21B102M501, and 31 General Purpose and Middle to High Voltage codes such as 1206B102J102, 1206B334K101, 0805B472M251 and 1206F474Z500. Those 38 are the ones to raise early.

What should a buyer selecting from this export actually do?

Three things, in this order, and the first one takes a minute. We hold 26 MLCC approval sheets covering all 16 export series, listed with their source URLs in INDEX_MLCC_series.csv, and we will send the one covering your part number as a PDF rather than a brochure. Against 432 flagged rows out of 24,026, the odds of hitting one at random are low — but 44.9% of them are 1206 and 74.8% are 1206 or 0805, which are exactly the case sizes a 200 V to 4 kV design lands on, and the Middle to High Voltage series carries 236 of the 432 on its own.

1. Check the thickness against the datasheet, not the remark. On 361 of 373 pairs the flag marks a non-standard T value. If your board clearance is tight, the flagged row may be the one you want — and if it is not, the unflagged twin carries the same part number. Ask us for the Walsin approval sheet covering your series and the thickness-by-size table settles it. See middle and high voltage MLCC, 200 V to 4 kV.
2. Cross the whole list in one pass and read the differences. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool. It is matched against Walsin’s published catalogue and returns candidates field by field, with every difference from your original stated rather than hidden. Filter by commercial or automotive grade, or for soft termination, high temperature, safety certified, high Q / low ESR or low profile.
3. Ask us to confirm orderable status before design-in, and check what is physically in Hong Kong on ready stock. That page is a dated snapshot as at 23 September 2026, not a live feed, and 864 of its 1,125 codes are MLCC. A part number appearing in the snapshot is the strongest evidence available to us that it is held as a standard line.

The full range sits on the Walsin MLCC page. Check us while you are at it: UL file E182369 covers the safety capacitor line and is searchable in UL’s own public database in about thirty seconds.

The short version

432 of the 24,026 rows in Walsin’s combined MLCC export are flagged as customized, 1.8% of the file, across 10 of the 16 series and concentrated at 1206 with 194 rows and 0805 with 129. The flag is written five ways for one sentence and two ways for the other, including 311 rows with a line break inside the cell, so no single exact-match filter catches more than 311 of them. 411 distinct part numbers carry it and 373 of those 411 also appear on an unflagged row, differing on the thickness column in 361 cases and on nothing at all in 12. Only 38 part numbers exist as a flagged row alone, among them MT18B224K100, ST21B104K500 and SH21B102M501. The part number is twelve characters and none of them tells you which row you are reading. The thickness answer is in the Walsin approval sheet; the stock answer is in the snapshot as at 23 September 2026. A customized-product remark is not a withdrawal notice. Qualification stays with you.

Send us the capacitor lines off your BOM and we will tell you which part numbers carry a customized flag, whether an unflagged twin exists at a different thickness, and which of them was in Hong Kong on 23 September 2026. If a selector has ever quoted you one of the 38 flagged-only codes as a stock item, tell us which — that is the case we most want to put in front of Walsin.

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Frequently asked questions

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