MLCC Rated Voltage Audit for the Netherlands: 1 of 16 Walsin Series Calls It Impulse Voltage, and 17 of 24,025 Rows Contradict Their Own Part Number

We ran the MLCC rated voltage audit nobody had run: every one of the 24,025 real rows in Walsin’s MLCC export, checked against the voltage code table in its own approval sheet. One of 16 series labels that field impulse voltage. 361 rows carry a code their own sheet never defines. 17 rows contradict themselves.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds 26 Walsin Technology (Walsin) MLCC approval sheets and the 24,026-row combined export 00_ALL_MLCC_parts_combined.xlsx. For a Netherlands engineer specifying a mains-adjacent or DC-link part, the open question since we published the S2 safety finding has been simple: is any other series mislabelled the same way? This post answers it by auditing all 16 export series, not one. We parsed the export and we read all 26 PDFs ourselves. Every part number below is real.

Does any Walsin MLCC series other than S2 label its Rated Voltage column impulse voltage?

No. We read all 26 MLCC PDFs we hold and searched every page. The word “impulse” appears in exactly four of the 26 files: the three safety capacitor sheets — 16_Safety_X1Y2_General_S2.pdf, 17_Safety_X1Y2_Automotive_S2_H.pdf and 18_Safety_X2_S3.pdf — and the 65-page full catalogue that reprints them. On the other 22 sheets the ordering-key field is labelled “Rated voltage”, and 20 of those additionally print the heading “Rated voltage (WVDC)” on their general electrical data page. WVDC is working volts DC. That is the figure a derating calculation needs.

So the mislabel is real, it is confined to the safety capacitor family, and only one of those three safety sheets has any export rows behind it. We have not seen this audited across a whole capacitor catalogue anywhere.

How many of the 16 MLCC export series could we check against a datasheet, and how many could we not?

All 16, and six more we could not check at all. We hold an approval sheet for every series that has export rows — 16 of 16 — and that is the reason this audit was possible. Six further series have a full Walsin approval sheet on file and zero rows in the parametric export: the VT soft-termination automotive series, the RT microwave automotive series, the RH microwave high-reliability series, the S3 X2 safety series, Mega Cap M and Mega Cap V.

Those six cannot be audited, because there is no export column to compare the sheet against. S3 is the sharpest loss for a Netherlands mains-input design: it is the X2 safety series, it holds third-party certification, and the catalogue data for it does not exist on our side. It is on our request list.

How many rows carry a voltage code their own approval sheet does not define?

361 of 24,025. We took the last three characters of every part number — the voltage code position in Walsin’s own ordering key — and looked it up in the code table printed in that series’ sheet. 23,647 rows decode cleanly and agree with the Rated Voltage column. 361 do not decode at all.

Two of these matter to a designer. RF02N0R2A160 and the 153 rows beside it put a 16 V step into a microwave series whose own sheet publishes 6.3, 10, 25, 50, 100, 200, 250, 500 and 1500 V and nothing else. And SG43B332K302 is a 1812 part at 3,000 Vdc in a series whose sheet covers 0603, 0805 and 1206 up to 2,000 V — outside its governing document on two fields at once.

Which rows disagree with the voltage code inside their own part number?

17 of 24,025. These are the rows where the Rated Voltage column and the voltage code printed inside the part number decode to two different voltages. Every code below is defined in that series’ own sheet, so this is not a missing-code problem. It is a contradiction.

Five of the 17 are 10x or more apart. Four are 0201 high-Q parts with an identical specification and four different tolerance codes, so the error travelled with a block of rows rather than a single typing slip. And 2225N103J101 occupies two rows with contradictory voltages — the part number alone does not identify which row you get.

What is the S2 working voltage, and why does it appear nowhere in the export?

Because the export carries the impulse figure in that column instead. We established this on 6 October 2026 and published it in the S2 rated voltage finding: all 173 S2 rows read 5000Vdc or 6000Vdc, and the approval sheet’s ordering key labels that field “Impulse voltage” — “502: 5000V Impulse Voltage”. Page 4 of 16_Safety_X1Y2_General_S2.pdf heads the same figure “Peak impulse voltage 5000V ~ 6000V”.

The working voltage is on the capacitance-range pages and nowhere in the export. For the UL and TUV certified range the sheet prints X1 310 Vac, Y2 250 Vac, and 1500 Vdc on all models. For the CQC range it prints 250 Vac. S242B471K502 and S242N100J502 are real S2 part numbers whose export row shows 5000Vdc; neither row carries the 310 Vac, the 250 Vac or the 1500 Vdc anywhere.

Which Walsin MLCC series reconcile on every single row?

Four of the 16, and 981 rows between them. We checked all 24,025 rows series by series. The MG high-reliability series (788 rows), the Feed Through FT series (8 rows), the High Temperature HT series (128 rows) and the Low Profile TT series (57 rows) return zero undefined codes and zero contradictions — every voltage code decodes against its own sheet and agrees with its own column. That is 4.1% of the catalogue fully reconciled against its governing document, and eleven series each holding at least one row that is not.

The FT series is clean on all eight of its rows, but its sheet tabulates ten part numbers in the rated-value table and the export returns eight, so two documented feed-through parts have no matching row in the export and cannot be quoted at all.

What should a Netherlands engineer do before specifying a voltage from this export?

Three things, and the first takes a minute. Decode the last three characters of the part number against the ordering key in the sheet — if the code and the column disagree, you are on one of the 17 rows above and the voltage is unresolved. For any S2 safety part, ignore the export’s 5000 or 6000 Vdc and work from the sheet’s X1 and Y2 AC figures.

1. Ask for the sheet, not the row. We hold 28 Walsin datasheets, 451 pages. Name your part number and the governing PDF arrives as a file.
2. Cross the whole list in one pass. Paste up to 500 part numbers or drop an Excel or CSV into the free cross reference tool, filter for safety certified, and read every stated difference rather than a claimed match.
3. Check what is physically in Hong Kong on ready stock — a dated snapshot of part numbers as at 23 September 2026, not a live feed.

For the safety classes see X1/Y1 against X1/Y2 safety capacitors, and for what the export files can and cannot answer, what Walsin’s 203 export files can and cannot answer. The full range sits on the Walsin MLCC page.

The short version

One of Walsin’s 16 MLCC export series labels its voltage field impulse voltage, and it is the S2 safety series — 173 rows, already established and published by us. No other series shares that mislabel. What the population audit surfaced is different and larger: 361 of 24,025 rows carry a voltage code their own approval sheet’s ordering key does not define, and 17 rows hold a Rated Voltage value that contradicts the voltage code printed inside their own part number, five of them by a factor of ten or more. Four series — MG, FT, HT and TT, 981 rows — reconcile perfectly. Six further series have a datasheet and no export rows, so they cannot be checked at all. Qualification stays with you.

Send us the Walsin or crossed part numbers off your Netherlands bill of materials and we will decode the voltage code against the governing approval sheet, row by row, and tell you which ones do not reconcile. And a question for anyone who has built a selector on top of a manufacturer export: when the column and the part number disagree, which one does your tool believe?

Frequently asked questions