Disc Capacitor Lead Spacing: The Column Is Empty on All 929 Rows, and on 350 of Them the Published Fields Do Not Fix the Footprint

Walsin’s ceramic disc capacitor export declares a Lead Spacing column and fills it zero times in 929 rows. We then tested whether the fields it does fill pin the footprint down. On 350 of the 929 part numbers they do not: the same capacitance, tolerance and rated voltage is published on parts with two or three different body sizes.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the ceramic disc capacitor parametric export published by Walsin Technology (Walsin) — Walsin_DiscCap_ALL.xlsx, 929 rows — and no disc capacitor datasheet of any kind. None of the 28 Walsin datasheets we hold, 451 pages, covers this line, so every mechanical statement below is read out of the export and flagged, and we link only to Walsin’s own site for specifications. Every part number is real. A through-hole part that does not fit the footprint already on the board is a respin, not a substitution, which is why we went looking for this.

Does Walsin publish a lead spacing for any of its 929 disc capacitors?

No. Not one row. We opened Walsin_DiscCap_ALL.xlsx and counted the non-empty cells in every one of its eleven columns. Lead Spacing is empty on all 929 rows, and so are T.C., Packing, SPQ and MOQ — five of eleven columns carry nothing at all. Six columns do the entire job of describing a leaded, through-hole, mains-rated part, and none of the six is a dimension.

Column in Walsin_DiscCap_ALL.xlsx	Rows with a value, of 929	Distinct values	Match / mismatch against what a footprint decision needs
Part Number	929	929	Match — the only unique key
Series	929	14	Mismatch — a free-text label, not a dimension
Dielectric	929	11	Mismatch — electrical, and 11 strings for 7 dielectrics
Capacitance	929	59	Mismatch — electrical
Tolerance	929	4	Mismatch — electrical
UR	929	15	Mismatch — electrical, and two rating systems in one column
T.C.	0	0	Mismatch — declared, never filled
Lead Spacing	0	0	Mismatch — the one mechanical column, declared and never filled
Packing	0	0	Mismatch — declared, never filled
SPQ	0	0	Mismatch — declared, never filled
MOQ	0	0	Mismatch — declared, never filled

We also checked whether any other Walsin family fills these headers. Across all eight product directories, MOQ is declared in three files and only in the varistor and disc capacitor exports; SPQ is declared in 21 files; both are empty everywhere. The two lines that bothered to declare a minimum order quantity are the two lines that publish no quantity at all.

Where does the only per-part mechanical figure actually live?

In the last three characters of the part number. All 929 disc capacitor codes are exactly twelve characters long, and characters ten to twelve are a three-digit body code taking twelve distinct values: 040, 050, 060, 070, 080, 090, 100, 110, 120, 130, 140 and 190. There is no 150, 160, 170 or 180 anywhere in the file. We counted every one.

The code is not decorative. We grouped all 929 rows by it and took the median capacitance in each group, and the ladder climbs without a single reversal from 040 to 140.

Body code	Part numbers	Median capacitance in that group	Lowest in group	Highest in group	Match / mismatch against reading the code as a size
040	95	200 pF	15 pF	4,700 pF	Match — smallest group, smallest median
050	163	470 pF	15 pF	5,000 pF	Match
060	269	120 pF	10 pF	10,000 pF	Mismatch on median — the busiest code, and it spans the whole range
080	100	1,000 pF	47 pF	22,000 pF	Match
100	57	3,300 pF	360 pF	10,000 pF	Match
120	26	4,700 pF	1,800 pF	10,000 pF	Match
140	7	10,000 pF	4,700 pF	10,000 pF	Match — largest published body, highest median
190	1	1,000 pF	1,000 pF	1,000 pF	Mismatch — one part, and its own capacitance is in dispute

The single 190 part is YU0AS103M190, and it is the one row in 929 whose capacitance code disagrees with its Capacitance column — we published that count separately in the disc capacitor capacitance code. The largest body size in the entire range exists on exactly one part number, and that part number is also the file’s only capacitance defect.

Do capacitance, tolerance and rated voltage decide the body size?

Not on more than a third of the range. We grouped all 929 rows by the three electrical fields the export actually fills — Capacitance, Tolerance and UR — and counted how many distinct body codes sat inside each group. 691 signatures exist. 147 of them span more than one body code, and those 147 signatures hold 350 of the 929 part numbers. The worst span three different body sizes for one published electrical specification. We have not seen this counted anywhere.

Part number	Dielectric	Capacitance	Tolerance	UR	Body code	Match / mismatch against YU0AH152M080
YU0AH152M080	YU (Y5U)	1500 pF	±20%	X1-400Vac / Y1-250Vac	080	the reference
YV0AH152M070	YV (Y5V)	1500 pF	±20%	X1-400Vac / Y1-250Vac	070	Match on all four published electrical fields, mismatch on dielectric and body code
YU0AH152M060	YU (Y5U)	1500 pF	±20%	X1-400Vac / Y1-250Vac	060	Match on every published field including dielectric, mismatch on body code
YU1AC222M080	YU (Y5U)	2200 pF	±20%	X1-440Vac / Y2-300Vac	080	different rating; shown for the same three-way split
YU1AC222M070	YU (Y5U)	2200 pF	±20%	X1-440Vac / Y2-300Vac	070	Match on every published field, mismatch on body code
YV1AC222M060	YV (Y5V)	2200 pF	±20%	X1-440Vac / Y2-300Vac	060	Match on the four electrical fields, mismatch on dielectric and body code

Look at the third row. YU0AH152M080 and YU0AH152M060 agree on every single field the export publishes — dielectric, capacitance, tolerance and rating — and differ only in the three characters the export never explains. A selector built on the published columns returns both and cannot tell you which one fits the holes you already have.

Which body sizes exist, and which half of the range can a safety part reach?

Not the small half. We split the 929 into the 367 safety certificated rows and the 562 commercial rows and tabulated the body code for each. All 95 parts carrying the smallest body code 040 are commercial. Not one safety certificated disc capacitor in the file reaches it. The safety range starts at 050, and only 25 of 367 safety parts sit there.

Body code	Commercial parts	Safety certificated parts	Match / mismatch for a designer moving a commercial part to a Y position
040	95	0	Mismatch — no safety part exists at the smallest body
050	138	25	Mismatch — 6.8% of the safety range
060	118	151	Match — the busiest body code on both sides
080	51	49	Match
120	7	19	Mismatch — the safety range outweighs the commercial one here
190	0	1	Mismatch — safety only, and a single part

That is the practical consequence. A commercial Class II disc at 040 has no safety certificated counterpart at the same body size anywhere in Walsin’s range, so moving a part across the isolation barrier is a layout change before it is a specification change. The class split itself is set out in Class I against Class II disc capacitors, and the X1 rating that decides the Y class is in X1/Y1 against X1/Y2 safety capacitors. The line sits on the Walsin disc capacitor page.

Does the word small size in the series name close the gap?

Only partly, and only for safety parts. 199 of the 929 Series strings contain the words “small size”, and all 199 are safety certificated rows. That is the only other mechanical token anywhere in the export, and it is binary: a part is either flagged small or it is not. It does not tell you how small, it does not appear on a single one of the 562 commercial rows, and it does not separate 050 from 060.

So the full mechanical content of Walsin’s 929-row disc capacitor export is one unexplained three-digit code and one adjective on 21.4% of the rows. We measured it, and that is everything there is.

What do you have to ask for before you commit a through-hole footprint?

A drawing, for the exact part number, from Walsin. We will say that plainly rather than hand you a body code and let you infer a lead pitch from it. We hold 28 Walsin datasheets, 451 pages — ask for the one covering your part number and it will be in your inbox, and if the answer for this line is that none exists, you get that answer the same day instead of at layout freeze.

We will not tell you a part is equivalent. We will show you where it differs — and on a leaded disc the field we cannot show you is the one that decides whether it goes on the board.

1. Cross the electrical specification first, then settle the mechanics separately. Paste 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. Send us the existing lead pitch in millimetres, not the body code. We will come back with which Walsin codes are candidates and which ones we cannot confirm without a drawing.
3. 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. No disc capacitor appears in it.

The short version

We counted every cell in Walsin_DiscCap_ALL.xlsx. Five of eleven columns are empty on all 929 rows, and the only mechanical column among them, Lead Spacing, is one of the five. The only per-part mechanical figure in the whole file is a three-digit code in the last three characters of the part number, taking twelve values from 040 to 190, with 190 on a single part that is also the file’s only capacitance defect. Then we tested the fields that are filled: 147 of 691 electrical signatures span more than one body code, putting 350 of 929 part numbers in a position where capacitance, tolerance and rated voltage do not determine the footprint. No safety certificated part reaches the smallest body code, and 199 rows carry the word “small size” as their only size statement. We hold zero disc capacitor datasheets and we are not going to guess a dimension.

Send us the Y capacitor and decoupling lines off your bill of materials with the lead pitch your board is already cut for, and we will tell you which Walsin codes are candidates and which ones we cannot confirm without a drawing from Walsin. Qualification stays with you. And a question back: when your last through-hole capacitor was second-sourced on a parametric match, who checked the hole spacing?

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Frequently asked questions

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