Walsin’s Five Special-Requirement MLCC Filters Share Zero Part Numbers

We counted all ten pairwise overlaps between the five special-requirement filters. Every single one is zero. An MLCC soft termination search returns 1,671 part numbers. Add high temperature, safety certification, high Q or low profile to it and you get nothing at all. Five filters, 3,726 parts, never two on one part number.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 of Walsin Technology (Walsin) parametric export files and 28 Walsin datasheets. This post is measured from the per-series MLCC exports in that set — 18_SoftTerm_SG.xlsx, 20_SoftTerm_SH.xlsx, 04_Automotive_SoftTerm_ST.xlsx, 09_High_Temperature_HT.xlsx, 15_Safety_X1Y2_S2.xlsx, 08_High_Q_Low_ESR_HH.xlsx and 11_Low_Profile_TT.xlsx — and every part number below is real. Every count is a count of part numbers, not pieces.

The five filters on the free cross-reference tool are soft termination, high temperature, safety certified, high Q / low ESR, and low profile. They are the most useful thing on the page and the least documented. So we counted what each one can return before you try it.

How many MLCC part numbers do the five special-requirement filters reach?

Three thousand seven hundred and twenty-six of 23,601, which is 15.8% of the MLCC catalogue. We took the distinct part numbers behind each filter and added them up — and the sum of the five is exactly the size of the union, because no part number appears twice.

Filter	Walsin series behind it	Distinct part numbers	Case sizes present	Voltage range	Dielectrics
Soft termination	SG, SH, ST	1,671	0402 → 2225	6.3 – 3,000 Vdc	X7R 1,215 · NPO 463 · X5R 27 · X7T 2
High Q / low ESR	HH	1,706	0201 → 0805	10 – 630 Vdc	NPO only, all 1,709 rows
Safety certified	S2	165	1808 → 2220	5,000 – 6,000 Vdc	NPO 87 · X7R 86
High temperature	HT	128	0402 → 1210	50 and 100 Vdc only	X8G 102 · X8R 26
Low profile	TT	56	0402 → 1210	6.3 – 100 Vdc	X5R 52 · X7R 5
Union of all five	—	3,726	—	—	—
Pairwise overlap, all ten pairs	—	0	—	—	—

We have not seen this counted anywhere. It is the figure that tells you whether the tool can serve your requirement before you spend an afternoon pasting part numbers into it, and it is also the figure that tells you when a zero-result screen is the catalogue speaking rather than the tool failing.

What does an MLCC soft termination search return, and where does it stop?

One thousand six hundred and seventy-one part numbers across three series, and it stops at 0402. We counted the case-size distribution across all three soft-termination exports: 82 rows at 0402, 299 at 0603, 388 at 0805, 523 at 1206, 177 at 1210, then 24 at 1808, 133 at 1812, 19 at 1825, 46 at 2220 and 16 at 2225. There is no 0201 soft-terminated part in Walsin’s catalogue at all, which is consistent with the physics — the polymer layer needs room — but it is not something any selector tells you before you filter.

Soft termination is also the only one of the five filters that goes high. It is the only filter reaching 3,000 Vdc, and it carries 18 distinct rated voltages against the safety filter’s two. If your reason for wanting soft termination is board flex on a large, high-voltage part, the shelf is genuinely deep. If your reason is a 0402 under a BGA, the shelf is 82 parts, and if your footprint is 0201 it is empty.

Part number	Series	Size	Dielectric	Capacitance	Voltage	Match / mismatch vs 100 nF 0603 X7R 50 V, soft-terminated
ST18B473K500	ST, automotive, AEC-Q200	0603	X7R	47 nF	50 Vdc	Match on size, dielectric, voltage; mismatch — 47 nF, not 100 nF
ST21B104K500	ST, automotive, AEC-Q200	0805	X7R	100 nF	50 Vdc	Match on capacitance, dielectric, voltage; mismatch — 0805 footprint
ST18B223K500	ST, automotive, AEC-Q200	0603	X7R	22 nF	50 Vdc	Match on size, dielectric, voltage; mismatch — 22 nF
ST18B152K500	ST, automotive, AEC-Q200	0603	X7R	1,500 pF	50 Vdc	Match on size, dielectric, voltage; mismatch — two decades low

We will not tell you a part is interchangeable. We will show you where it differs, and here the difference is capacitance at the footprint you asked for. Confirm against the Walsin datasheet and qualify in your own circuit.

Why does combining two special-requirement filters return nothing?

Because the five filters are five separate series families, and Walsin builds each special requirement into its own series rather than as an option on another. We checked all ten pairs and every intersection is empty: soft termination against high temperature, 0. Soft termination against safety, 0. Soft termination against high Q, 0. Soft termination against low profile, 0. High temperature against safety, high Q, low profile — 0, 0, 0. Safety against high Q and low profile — 0, 0. High Q against low profile, 0.

So the practical rule is harder than it looks on a filter panel with five checkboxes: the checkboxes are mutually exclusive, and a user interface that lets you tick two of them is offering a combination the catalogue does not contain. That is not a criticism of the tool, which is reporting the shelf accurately. It is the thing we would rather you knew in advance.

There is one near-exception worth naming precisely, because it is the combination most often asked for. Soft termination and automotive qualification do coexist, in the ST series — 118 part numbers, AEC-Q200 qualified, 0402 through 2220. Automotive is not one of the five special-requirement filters; it is the grade filter, and the grade filter does combine. If your requirement is “soft-terminated and automotive”, you have 118 candidates. If it is “soft-terminated and high temperature”, you have none.

Which of the five filters reaches 0201, and what is its ceiling there?

Only high Q / low ESR, and its ceiling at 0201 is 9.1 pF. We checked every case-size column in all five filter sets. High Q holds 217 rows at 0201; soft termination, high temperature, safety certified and low profile hold none, and the smallest size any of the other four reaches is 0402 — 82 rows for soft termination, 7 for high temperature, 4 for low profile, and 1808 for safety.

Then read the capacitance column, because the 0201 door opens onto a small room. All 1,709 high Q rows are NPO, with no X7R, X5R or X8R anywhere in the series, and at 0201 the published values run from 0.1 pF to 9.1 pF. HH03N0R1B500 at 0.1 pF is the bottom of it. So the only special-requirement filter that reaches 0201 is one that cannot give you more than about 9 pF there, and cannot give you a Class II dielectric at any size. For an RF matching network that is exactly right. For decoupling it is no use at all, and you will find that out faster from this paragraph than from the tool.

Why is there no high-temperature Walsin MLCC above 100 Vdc?

Because the HT series holds 128 part numbers and every one of them is rated 50 Vdc or 100 Vdc. We read the rated-voltage column across the whole file: two distinct values, nothing else. The dielectric split is X8G on 102 rows and X8R on 26, and the case sizes run 0402, 0603, 0805, 1206 and 1210 — so there is no high-temperature part at 0201 and none at 1812 or above either.

That shapes the design decision in a way a brochure line about 150 °C operation does not. A high-temperature rail above 100 V has no high-temperature part behind it in this catalogue, and the honest answer is to look at the Middle to High Voltage series and accept its temperature grade, or ask Walsin directly. One more thing we found while counting, and we are flagging rather than asserting: all 26 X8R rows sit in the HT series, whose approval sheet documents X8G only and never defines the R code.

Which six Walsin MLCC series return zero parts on Walsin’s own product search?

Six, and we can name them because each one ships as a two-row stub rather than a parts list. We opened all 22 per-series MLCC export files. Sixteen carry parts. Six carry a single line reading “Parts listed on Walsin product search: 0” and a note, and they are the Automotive Soft Termination (VT) series, Low Inductance 0612, Open-mode (OP), Safety Certificated X2/Y3 (S3), Soft Termination SG High Voltage, and Soft Termination SH High Voltage.

Series with a stub file	What it would serve	Parts listed on Walsin’s product search
VT — automotive soft termination, AEC-Q200 and VW80808	The automotive soft-term requirement above ST’s ceiling	0
S3 — safety certificated X2/Y3	X2/Y3 safety, the class below S2	0
SG High Voltage — Cu-poly soft termination	Soft termination above the standard SG range	0
SH High Voltage — Ag-poly soft termination	Soft termination above the standard SH range	0
0612 — low inductance	Reverse-geometry decoupling	0
OP — open-mode design	Failure-mode-constrained line filtering	0

This is why the per-series files total 24,038 rows and the combined export totals 24,026: twelve of those rows are the six stubs. And it explains three of the empty filter combinations above rather than leaving them mysterious — “soft terminated and high voltage” and “soft terminated and automotive beyond ST” are not missing from the tool, they are series with nothing listed behind them.

The S3 line deserves one sentence on its own. We hold a CQC certificate issued against the S3 series, CQC20001280136, and Walsin’s product search lists zero S3 parts. We are not going to tell you what that means, because we do not know. We are going to tell you we found it, and that it is on our list to Walsin.

What should a buyer in the Netherlands do with this?

Rank your special requirements before you cross, because you are picking one. The trade press reported MLCC lead times of 26 to 32 weeks on high-grade series through 2026 as AI server and EV build-outs drew on the same capacity, so a second source is worth finding early — and the fastest way to waste that effort is to search for a combination of two special requirements that no series contains.

1. Decide which single special requirement is non-negotiable. Soft termination for board flex, high Q for RF, X8-grade for temperature, 5 kV for safety, sub-millimetre for height. You will get one of them, plus the grade filter.
2. Cross the whole BOM in one pass. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool. It decodes 18 manufacturers’ part numbers and matches against 800,000+ crossable Walsin part numbers, returning candidates field by field with every difference from your original stated rather than hidden.
3. Treat a zero-result screen as information. If soft termination plus high temperature returns nothing, that is the catalogue, not a bug. Send us the requirement and we will tell you which single filter gets you closest and what you give up.
4. Check what is physically in Hong Kong on ready stock before you commit to a production slot. That page is a dated snapshot as at 23 September 2026, not a live feed.

Check us while you are here. UL file E182369 is searchable in UL’s own public database in about thirty seconds, and the TUV certificates R50381780 and R50195920 are named and numbered for the same reason. We also hold 28 Walsin datasheets, 451 pages — ask for the one covering your part number and it will be in your inbox rather than in a brochure.

For the soft-termination decision itself, see Soft termination MLCC: SH, SG, ST and VT and Flex cracking and board bend: why soft termination exists. For the high Q end of the same catalogue, see High Q and low ESR MLCC for RF. The full range is on the Walsin MLCC range page.

The short version

Walsin’s five special-requirement MLCC filters reach 3,726 of 23,601 part numbers and share not one part number between them — all ten pairwise overlaps are zero. An MLCC soft termination search returns 1,671 parts, reaches 3,000 Vdc and stops at 0402. High Q / low ESR is the only filter that reaches 0201, is entirely NPO, and tops out around 9.1 pF there. High temperature is 128 parts at 50 and 100 Vdc only. Safety certified is 165 parts at 1808 and above. Low profile is 56 parts. And six further MLCC series return zero parts on Walsin’s own product search, which is why three of the empty filter combinations are empty.

Send us your MLCC lines with the one special requirement that cannot move, and we will come back with Walsin candidates field by field, differences included — then tell you which of them was in Hong Kong on 23 September 2026. If you think two of those five filters ought to combine, tell us which two: that is the question we most want to put to Walsin, and your enquiry is what gets it asked.

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Frequently asked questions

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