Chip Inductor Q Factor: 1,082 of 5,410 Walsin Rows Publish Zero, and No Column States the Test Frequency

Chip inductor Q factor is the one field an RF matching network cannot be designed without, and we counted how often it is actually published. 1,082 of Walsin’s 5,410 real inductor rows carry a literal zero in Q Min. No column anywhere in that export states the frequency at which any Q was measured.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 Walsin Technology (Walsin) parametric export files and 28 Walsin datasheets running to 451 pages — of which zero cover the inductor line. Everything below is measured from Walsin_Inductor_ALL.xlsx, with the QA row Test123999 excluded from every count, so the denominator is 5,410 and not 5,411. Every part number is real. For specifications beyond what that file publishes, go to Walsin’s own site at passivecomponent.com and ask us for the sheet in writing.

How many of Walsin’s 5,410 chip inductors publish a minimum Q at all?

4,328 of 5,410. We parsed the Q Min column on every real row and found it is never blank — it is an integer column with no empty cells at all, which is exactly why a selector reads it as fully populated. It is not. 1,082 rows carry a literal 0, and a Q of zero is not a specification, it is an absence written in a numeric field. The split is not random either.

What the Q Min column holds	Part numbers	Share of 5,410	Match / mismatch against “Q is published”
A positive minimum Q, 4 to 130	4,328	80.0%	Match — a usable figure, frequency still unstated
A literal 0, on a ferrite bead (Unit = Ω)	641	11.8%	Mismatch — Q is not the right parameter for a bead; impedance is
A literal 0, on a genuine nH or µH inductor	441	8.2%	Mismatch — the part is an inductor and the field is empty in all but form
Blank or null	0	0%	—

The middle row is defensible. A ferrite bead is specified by impedance at a frequency, not by Q, and all 641 Ω-unit rows read zero on Q without exception — we checked every one. The bottom row is the problem: 441 parts that are sold as inductors, measured in nanohenries or microhenries, publish nothing where the loss figure belongs. We have not seen this counted anywhere.

At what frequency was the Q measured, and does the export say?

It does not. There are fourteen columns in the inductor export and we read all of them. The impedance column names its own test condition in the header — Impedance (100MHz[Ω]) — so Walsin clearly does state a test frequency where the data owner thought it mattered. Q Min carries no frequency in its header, no companion column, and no footnote row anywhere in the file.

That is not a small omission. Q on a chip inductor rises and then falls with frequency, so a bare number such as 21 is only actionable once you know whether it was taken at 100 MHz, 500 MHz or 1.8 GHz. A 0402 part quoted at 100 MHz and the same part quoted at 1 GHz are two different design decisions with one number between them.

Which inductor series publish a Q, and which publish nothing?

30 of Walsin’s 47 inductor series publish a zero on every single row. We grouped all 5,410 rows by Series and counted. 11 series publish a positive Q on every row and hold 4,163 part numbers between them. 30 series publish nothing at all and hold 927. Six series are mixed, 320 parts, and those are the ones that will quietly break a filter written at series level.

Series	Rows	Rows with a positive Q	Positive Q range	Match / mismatch against a Q-led shortlist
WLCW	791	791	13 to 98	Match — safe to filter at series level
WCI	720	720	15 to 85	Match
WCA	622	622	15 to 85	Match
WQCW	569	569	15 to 85	Match
WLCM	559	559	4 to 14	Match on publication, mismatch on magnitude — the whole series sits under 15
MCI	501	501	4 to 14	Match on publication, mismatch on magnitude
WLFW/WFI	197	141	10 to 50	Mismatch — 56 of 197 rows publish zero inside one series name
WQBD	45	4	7 to 9	Mismatch — 41 of 45 publish zero
MCB / MHC Automotive	150	0	none	Mismatch — the largest series in the catalogue with no Q at all
CSME	89	0	none	Mismatch
AIP	71	0	none	Mismatch

Two rows deserve a sentence. WLFW/WFI Series holds 197 parts and 56 of them publish zero, so a script that accepts the series and then trusts the field will carry 56 unspecified parts into a shortlist. And the 150-row MCB / MHC Automotive Series is the single largest block in the catalogue with no Q on any row — these are bead-type parts, so impedance is the right field, but an automotive RF front end still needs a loss figure and this export does not hold one. The impedance side of that trade is counted in ferrite bead against inductor at 100 MHz.

Does the same inductance at the same case size give you the same Q?

No — it varies by a factor of 2.6 at one point we checked in detail. We pulled every 10 nH part in a 1005(0402) case: 21 part numbers across seven series. The wirewound families publish Q Min 21. The multilayer families publish 8. Same inductance, same nominal case code, same board area, and a loss figure that differs by 13 points with no test frequency stated on either.

Part number	Series	Construction family	Q Min	RDC	Rated current	SRF(min) as printed	Match / mismatch against WLCW1005Z0J10NTB
WLCW1005Z0J10NTB	WLCW	wirewound	21	0.2 Ω	480mA	3.9	reference part
WQCW1005Z0J10NTB	WQCW	wirewound	21	0.2 Ω	480mA	3.9	Match on Q, RDC, current and SRF; mismatch on measured body — 1.19 × 0.64 mm against 1.0 × 0.5 mm
WCI1005CP10NJ	WCI	wirewound	21	0.2 Ω	480mA	3.9	Match on every electrical field; mismatch on series name and part-number format only
WCA1005CP10NJ	WCA	wirewound	21	0.2 Ω	480mA	3.9	Match on every electrical field; mismatch on series name only
WLCM1005Z0J10NTB	WLCM	multilayer	8	0.3 Ω	0.5A	3400	Mismatch — Q 2.6x lower, RDC 50% higher, current written in a different unit
MCI1005HQ10NJHBP	MCI	multilayer	8	0.3 Ω	0.5A	3400	Mismatch on Q and RDC; matches WLCM1005Z0J10NTB field for field
MCI1005HZ10NJHBP	MCI Automotive	multilayer	8	0.3 Ω	500mA	3400	Mismatch on Q; rated current written as 500mA where its commercial twin writes 0.5A

Read the last two columns together, because they are the whole argument. The SRF figure reads 3.9 on the wirewound rows and 3400 on the multilayer rows for the same 10 nH part — those cannot be the same unit, and we counted that separation across the whole file in self-resonant frequency in Walsin inductors. The rated current reads 480mA, 0.5A and 500mA in one column on three rows of one table. We will not tell you these parts are equivalent. We will show you where they differ, and here they differ in a field that is not even written in one unit.

What is the highest Q in the catalogue, and how many parts hold it?

130, on seven part numbers. We sorted all 5,410 rows by Q Min descending. The ceiling is 130 and every part that reaches it sits in the 20-part WQQC Series, including WQQC0908Z0J8N1PB at 8.1 nH and WQQC0908Z0J12NPB at 12.1 nH. Only 12 of 5,410 rows publish a Q of 100 or more, and 544 publish 60 or more. The floor on the positive side is 4, in the WLCM and MCI multilayer families.

WQQC is also the series with no case-size code: its Size column repeats the millimetre dimensions, so WQQC0806Z0J5N5PB reads 1.346*1.829 where every other series reads something like 1005(0402). If you shortlist by case code you will never see the highest-Q parts Walsin publishes, because they have no case code to match on. That is a selector failure, not a product failure, and it is worth ninety seconds of your time to check by hand.

For the full high-Q and tight-tolerance intersection across the catalogue, we have already counted it in choosing an RF matching inductor. This post is about whether the field is populated at all; that one is about what clears a threshold.

What has to arrive from Walsin before a Q figure can settle a matching network?

Three things, and we hold none of them today. We hold 28 Walsin datasheets and 451 pages, and not one page covers an inductor — so on this line we are reading the same export you can read, and we will say that rather than imply a depth of documentation we do not have.

1. The Q test frequency, per series. Without it, 21 and 8 are labels, not measurements.
2. Whether 0 means not characterised or measured as zero. 441 nH and µH parts turn on this answer.
3. A published tolerance or distribution on Q, because Q Min is a minimum and a matching network is designed against a range.

Until those land, do the thing the data does support. Cross your incumbent part through the free cross-reference tool — paste up to 500 part numbers or drop your Excel or CSV — and read every stated difference rather than a claimed match. Then check what is physically in Hong Kong on ready stock, 1,125 part numbers as at 23 September 2026, a dated snapshot and not a live feed. The full line sits on the Walsin inductor page. Our locations are Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation, and nowhere else: Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong. (852) 2628 4777.

The short version

4,328 of 5,410 Walsin inductor rows publish a positive minimum Q and 1,082 publish a literal zero — 641 of those are ferrite beads, where Q is the wrong parameter, and 441 are genuine nH or µH inductors where it is not. 30 of 47 series publish zero on every row; six mix populated and empty rows under one series name, which is where a series-level filter breaks. No column states the frequency any Q was measured at, while the impedance column states its own in the header. At 10 nH in a 0402 case the figure is 21 on four wirewound series and 8 on three multilayer series, and in the same table the rated current is written three ways. We hold no inductor datasheet, we say so, and qualification stays with you.

Send us the inductor lines off your bill of materials and we will return the published row for each one, with the empty fields marked empty rather than filled in with a plausible number. And a question back: when your selector last returned a Q of 21, did it tell you the frequency — or did you assume one?

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Frequently asked questions

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