Passive Component Cross Reference: Only 2 of 90 Columns Join Across All Eight Walsin Families, Measured for US Engineers

We treated a passive component cross reference as a join problem and measured it. Across the 114 Walsin export files that hold parts, 90 distinct column names appear. Exactly two exist in every file of all eight families and are populated on every row: Part Number and Series. Everything that actually decides a cross is family-local.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 Walsin Technology (Walsin) parametric export files and built a free cross-reference tool on top of them. This post is the join-key analysis behind that tool: for each of the eight product families we opened every file, listed every column, and counted how many rows actually carry a value in it. Every part number below is real and every one is in Walsin’s published catalogue. We have published the file census separately; this is the different question of what a single engine can work from.

What can a passive component cross reference actually join on across all eight Walsin families?

Two columns, and only one of them is a key. We opened all 203 export files, kept the 114 that hold at least one part number, and intersected the column sets family by family. Part Number and Series are the only two of 90 column names present in every file of all eight families and populated on 100% of rows. Size and Tolerance reach six families each. Nothing else reaches more than three. Series is a label, not a key — so a single engine has one join column and one grouping column, and that is the whole shared foundation.

Family	Files holding parts	Rows	Distinct column names	Columns in every file of the family and 100% populated	Match / mismatch vs the eight-family common denominator
MLCC	18	48,225	26	6	Match — carries both, plus dielectric, voltage, size, tolerance
Chip resistor	64	234,815	10	10	Match — every declared column is fully populated
Thin film	11	93,914	9	9	Match — same ten-column schema minus series group
Inductor	2	10,822	14	13	Match — richest family; only saturation current is partial
MOV	2	758	10	7	Mismatch — packing, pack quantity and order quantity all empty
Disc capacitor	1	929	11	6	Mismatch — publishes no Size column at all
RF	14	914	38	4	Mismatch — declares 38 names, 4 survive the test
Antenna	2	88	10	4	Mismatch — no Size, no Tolerance

75 of the 90 column names are declared by exactly one family. That is the number that decides how a cross-reference engine has to be built: there is no shared specification schema to normalise into. There are eight schemas with a common identifier bolted across them. We have not seen this counted anywhere.

How many of Walsin’s 203 export files actually hold a part number?

114, not 120. We have published that 83 of the 203 files return zero rows, leaving 120 non-empty files holding 390,477 rows. We re-opened all 120 for this post and found something the row count hides: six of those 120 files are non-empty but hold no Part Number column at all. Each holds exactly two rows, and the second row is a note stating that the series has a datasheet but no individual part numbers in Walsin’s searchable database.

File	Rows	Columns	What it actually holds
03_Automotive_SoftTerm_VT.xlsx	2	Series plus a series description	A note, no parts
10_Low_Inductance_0612.xlsx	2	Series plus a series description	A note, no parts
14_Open_Mode_OP.xlsx	2	Series plus a series description	A note, no parts
16_Safety_X2Y3_S3.xlsx	2	Series plus a series description	A note, no parts
17_SoftTerm_SG_HighVoltage.xlsx	2	Series plus a series description	A note, no parts
19_SoftTerm_SH_HighVoltage.xlsx	2	Series plus a series description	A note, no parts

So the honest figures are 114 files holding 390,465 part rows, and 89 of 203 files — 43.8% — carry no part number at all. Those twelve note rows also explain a result that looks like a defect: Series is the only column present in all 203 files, and the reason Part Number is not is these six files and nothing else. Remove them and the universal set becomes two columns. We counted 359,136 distinct values in the Part Number columns; one of them is the known QA test row in the inductor export, so the real figure is 359,135 part numbers.

Which fields does each family publish, and how many of them are populated?

It ranges from 13 down to 4, and the spread is not about family complexity. We counted, per family, the columns present in every file of that family and filled on every row. Inductor publishes 13 fully populated fields on 10,822 rows. RF publishes 4 on 914 rows while declaring 38 column names across its 14 files. The RF export is the most column-rich and the least usable in the same breath.

Family	Fully populated fields a cross can rely on	The fields themselves
Inductor	13	size, size in millimetres, thickness, inductance, unit, tolerance, impedance at 100 megahertz, minimum Q, self-resonant frequency, direct-current resistance, rated current, part number, series
Chip resistor	10	size, resistance, tolerance, temperature coefficient, rated power, packaging, termination, series group, part number, series
Thin film	9	as chip resistor, without series group
MOV	7	size, maximum working voltage, varistor voltage, tolerance, peak current, part number, series
MLCC	6	size, dielectric, rated voltage, tolerance, part number, series
Disc capacitor	6	dielectric, capacitance, tolerance, rated voltage class, part number, series
RF	4	size, pin description, part number, series
Antenna	4	dimension, working frequency range, part number, series

The MLCC result deserves a line of its own, because it is counter-intuitive. Capacitance is declared in every one of the 18 MLCC files that hold parts and is not populated on all of them — which is why it does not appear in the six. Four rows carry a datasheet path or a stray capital letter where the capacitance belongs, a defect we have published before. A column that is 99.98% populated is still a column an automated join has to handle as nullable, and that is the difference between a selector and a suggestion.

What does a two-column common denominator cost you, family by family?

It costs you the field you most wanted to filter on, and a different one in each family. We checked what each family does not publish: Size is absent entirely from the disc capacitor and antenna exports, and Tolerance is absent entirely from the RF and antenna exports. So the four things an engineer needs for any cross — the value, the tolerance, the rating and the footprint — are never all four available on the same basis across the eight families.

What a cross needs	Families that publish it, of 8	Where it goes missing
A unique identifier	8	nowhere — Part Number is clean
A family or series label	8	nowhere — Series is on every row
A footprint (Size)	6	disc capacitor, antenna
A tolerance	6	RF, antenna
A rated voltage	2	six families, including every resistor line
A rated power	2	six families, including every capacitor line

Two header defects make even the shared fields harder to script than the counts suggest. We read every column header as raw characters: two different Unicode ohm symbols appear, the Greek capital omega at code point U+03A9 on 2 headers and the dedicated ohm sign at U+2126 on 26. A string comparison between those two fails silently. And in the RF export the same quantity is spelled two ways by a single space — Insertion Loss (dB) against Insertion Loss(dB), and Impedance for Frequency 1 (Ω) against Impedance for Frequency 1(Ω) — so a join on header text splits one field into two.

Why can an engine not route a part to a family from its prefix?

Because eight two-letter prefixes are shared between families, and they cover most of the catalogue. We grouped all 359,136 distinct part numbers by their first two characters and checked which family each belongs to. No part number appears in two families — zero of 359,136 — so the full code is a clean key. But 214,903 part numbers, 59.8% of the catalogue, carry a two-letter prefix that more than one family uses.

Prefix	Families using it	Part numbers per family	Match / mismatch vs a prefix-based router
WF	chip resistor, thin film, inductor	76,554 / 58,314 / 109	Mismatch — 134,977 codes, three families, one prefix
MF	thin film, chip resistor	20,520 / 14,791	Mismatch — MF12Q10R0ATL is thin film, MF04H1R00DTL is thick film
SF	thin film, chip resistor, RF	15,080 / 10,690 / 3	Mismatch — SF12T1R00ATL is a resistor, SF11091582GC2T is a SAW filter
SR	chip resistor, MOV	12,871 / 379	Mismatch — SR25W1R00FTL is a resistor, SR180K05D is a varistor
RF	MLCC, RF, antenna	3,615 / 410 / 42	Mismatch — RF03N0R1A250 is a 0201 capacitor, RFASWA630PTF0E is a switch
MA	chip resistor, inductor	1,386 / 6	Mismatch — MA06X10R0FTL is an array, MAP1608STR24MMPK is an inductor
WT	chip resistor, inductor	98 / 28	Mismatch — WTCF2012Z0M670PB is an inductor
RG	RF, antenna	5 / 2	Mismatch — RGBLN1608070A1T is a balun, RGFRA1903041A1T is an antenna

RF is the one that bites hardest, because the prefix names a product family and an MLCC series at the same time: 3,615 Microwave Caps carry it, and so do 410 RF devices and 42 antennas. An engine that guesses the family from the first two characters gets a capacitor when it wanted a filter. That is why our tool indexes the whole code rather than the stem, and why MF04H1R00DTL and MF12Q10R0ATL return different field sets even though they look like siblings.

For the file-level census behind these counts, see what Walsin’s 203 export files can and cannot answer. For the columns that exist and discriminate nothing, see columns that look like selectors and select nothing. The RF line is on the Walsin RF page.

What should a US engineer send us instead of a filtered list?

The part number, and the one field you will not compromise on. With two universal columns and 75 single-family columns, a filter built across families will mislead you; a join on the exact code will not. Give us the code and the constraint, and we will tell you which of the eight schemas your candidate lives in and which fields that schema simply does not publish.

1. Paste the codes, not your filter criteria. Up to 500 part numbers, or drop your Excel or CSV, into the free cross-reference tool. It matches against Walsin’s published catalogue and states every difference rather than hiding it.
2. Name the field that must not move. If it is tolerance and your candidate is RF or antenna, we will tell you the export does not publish it rather than guess.
3. Check what is physically in Hong Kong on ready stock — a live public page showing a dated snapshot as at 23 September 2026, not a feed. Ask us for the current position.

The short version

We measured a passive component cross reference as a join problem across all eight Walsin families. 114 of 203 export files hold parts, carrying 390,465 rows and 359,135 real part numbers; six non-empty files hold a two-row note instead, and they are the only reason Part Number is not universal. Of 90 column names, two are present and fully populated across all eight families, Size and Tolerance reach six, and 75 belong to one family alone. Fully populated field counts run from 13 for inductor to 4 for RF and antenna. No part number appears in two families, but 214,903 of 359,136 share a prefix with another family, WF alone spanning three. We will not tell you a part matches. We will show you which fields the export never published. Qualification stays with you.

Send us a bill of materials that crosses two or three of these families and we will show you, column by column, where the data runs out and what we had to ask you for instead. Then tell us this: when a distributor’s selector returns a clean result across capacitors, resistors and filters at once, which of those 90 columns do you think it filtered on?

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Frequently asked questions

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