Y Capacitor Safety Selection: Disc Covers 400-760 Vac, Chip S2 Stops at 310

We measured Walsin’s two Y capacitor safety selection shelves field by field: 367 leaded disc rows and 173 surface-mount chip S2 rows. They share 26 of 36 capacitance values, and they share zero X1 voltage ratings — the chip shelf’s real ceiling, 310 Vac, sits below the disc shelf’s floor of 400 Vac.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin Technology (Walsin)’s disc capacitor export (Walsin_DiscCap_ALL.xlsx, 929 rows) and its chip safety export (15_Safety_X1Y2_S2.xlsx, 173 rows), plus the 14-page S2 approval sheet, 16_Safety_X1Y2_General_S2.pdf. This post is measured from those three files and from the Venatech Hong Kong ready stock snapshot as at 23 September 2026. Every part number below is real, and every count is a count of part numbers, not pieces.

What does a Y capacitor safety selection actually compare across two Walsin shelves?

Ten fields, and we checked all of them on both shelves. The disc shelf (367 of Walsin’s 929 disc rows) and the chip S2 shelf (173 of 24,026 MLCC rows) are the two places a Y capacitor lives in Walsin’s catalogue, and a selection between them is not a drop-in choice — it is a field-by-field trade.

Field	Disc safety shelf (367 rows)	Chip S2 shelf (173 rows)	Match / mismatch
Mounting	Leaded, through-hole	Surface mount, 1808/1812/2211/2220	Mismatch — different assembly process
Y class offered	Y1 (181 rows) and Y2 (186 rows)	Y2 only, 173 of 173 rows	Mismatch — no Y1 chip option exists
X1 rating range	400, 440, 500, 760 Vac	310 Vac (UL/TUV), 250 Vac (CQC)	Mismatch — no shared value, see below
Capacitance range	10 pF to 10,000 pF	3 pF to 10,000 pF	Partial match, see next section
Dielectric	SL, YP(Y5P), YU(Y5U), YV(Y5V)	NPO, X7R	Mismatch — no shared dielectric code
Dimensional data (L/W/T)	0 of 367 rows	170 of 173 rows	Mismatch — disc carries none
Termination data	Not applicable, leaded	7 of 173 rows, and all 7 hold a tolerance value, not a finish	Mismatch — neither side states a finish cleanly
Datasheet on file	0 pages	14 pages, 16_Safety_X1Y2_General_S2.pdf	Mismatch
Certificate named in a held document	None	TUV R50381780, UL E182369, CQC20001280137, printed on the approval sheet’s electrical-data page	Mismatch
Hong Kong stock, 23 Sep 2026 snapshot	0 part numbers	3 part numbers	Mismatch

Nine of ten fields mismatch outright. We will not tell you a part is equivalent across these two shelves. We will show you where it differs, and the voltage field is the one that decides whether either shelf is even eligible.

Where do the disc and chip S2 shelves overlap on capacitance, and by how much?

More than most engineers would guess. We matched the two shelves by nominal capacitance value: the disc safety shelf carries 36 distinct values and the chip S2 shelf carries 36 distinct values, and 26 of those 36 values appear on both shelves — 309 of the 367 disc rows and 150 of the 173 chip rows sit at a shared capacitance. We have not seen this cross-shelf overlap counted anywhere.

That is the good news for a bill of materials that only states a capacitance. It is also the trap, because a tool that matches on capacitance alone will offer you both shelves at, say, 100 pF — YP0AC101K060 on the disc side and S242N101K502 on the chip side — and capacitance is the one field where they agree.

Which requirement can only be met by a disc capacitor?

Any X1 classification above 310 Vac, and the entire Y1 class. We read the chip S2 approval sheet’s General Electrical Data table ourselves: it states “UL & TUV: X1 310Vac & Y2 250Vac & All model 1500Vdc” and “CQC: 250Vac” as the working rating, against an export column that shows only the 5000/6000 Vdc impulse figure. The disc safety shelf’s lowest X1 rating is 400 Vac, on 112 AH rows — already 90 Vac above the chip ceiling.

X1 rating	Disc rows	Chip S2 rows	Y class available
400 Vac	112	0	Y1 only
440 Vac	137	0	Y2 only
500 Vac	103	0	Both Y1 (54) and Y2 (49)
760 Vac	15	0	Y1 only
310 Vac (UL/TUV) or 250 Vac (CQC)	0	173	Y2 only

So a design calling for X1 400 Vac or higher, or for Y1 at any voltage, has exactly one shelf to look at. We have flagged this gap before at series level; measuring it against the chip shelf’s own datasheet figure, side by side, is new.

Which requirement can only be met by a chip S2 capacitor?

A reflow-solderable footprint, and a certificate number you can trace to a page we actually hold. The chip S2 shelf publishes L, W and T on 170 of its 173 rows in four SMD case sizes — 1808, 1812, 2211 and 2220 — which is what an automated line needs. The disc shelf publishes zero body dimensions on any of its 929 rows, safety or otherwise, so it cannot be specified for a reflow process from our data at all; it is leaded by construction.

The second gap is documentary. We searched every cell of Walsin_DiscCap_ALL.xlsx for the words TUV, CQC, UL and the standard number 60384, and for all five certificate numbers — TUV R50381780 and R50195920, UL file E182369, CQC20001280137 and CQC20001280136. Zero of 929 disc rows contain any of them, and we hold zero pages of disc datasheet to fill the gap. The chip S2 shelf’s own export is equally silent — zero hits there too — but we hold the 14-page approval sheet, and on its electrical-data page the certificate numbers are printed in black and white. A certificate you can point to a page for exists only on the chip side.

What does one 100 pF line look like across both shelves?

Fifteen candidates and zero that match on every field. We pulled every row at exactly 100 pF from both exports — 15 disc rows and 8 chip rows — and the two families never converge past capacitance.

Part number	Shelf	Dielectric	Tolerance	X1 / Y rating	Match / mismatch vs a 440 Vac Y2 line
YP0AC101K060	Disc	YP(Y5P)	±10%	X1-440Vac/Y2-250Vac	Match on class and X1 voltage; mismatch — leaded, no datasheet on file
SL0AC101J090	Disc	SL	±5%	X1-440Vac/Y2-250Vac	Match on class and voltage; mismatch — SL dielectric, tighter tolerance
YP0AH101K060	Disc	YP(Y5P)	±10%	X1-400Vac/Y1-250Vac	Mismatch — Y1 class, lower X1 rating
YP0AS101K070	Disc	YP(Y5P)	±10%	X1-760Vac/Y1-500Vac	Mismatch — Y1 class, highest X1 on either shelf
S242B101K502	Chip S2	X7R	±10%	X1-310Vac/Y2-250Vac (datasheet)	Match on Y2 class and 250 Vac Y side; mismatch — X1 well below 440, SMD 1808
S243N101K502	Chip S2	NPO	±10%	X1-310Vac/Y2-250Vac (datasheet)	Match on Y2 and Y-side voltage; mismatch — NP0 at 1812, X1 shortfall
S252N101J502	Chip S2	NPO	±5%	X1-310Vac/Y2-250Vac (datasheet)	Match on Y2 and Y-side voltage; mismatch — 2211, X1 shortfall
S252N101J602	Chip S2	NPO	±5%	X1-310Vac/Y2-250Vac (datasheet)	Match on Y2 and Y-side voltage; mismatch — 6000 Vdc impulse variant, X1 shortfall

Every chip S2 row matches the Y-side voltage of a 440 Vac disc line and mismatches on the X1 side. Qualification stays with you — confirm against both the disc export and the S2 approval sheet before either part enters a technical file.

Is either shelf actually sitting in Hong Kong stock today?

Only the chip shelf, and only barely. We checked the Venatech ready stock snapshot as at 23 September 2026: of its 1,125 catalogue codes, three are chip safety capacitors — S242B102K502, S252B222K502 and S252B471K502ZT — and none is a disc capacitor. The entire 367-row disc safety range is an order-in line.

That is a dated snapshot, not a live feed, and it moves. We hold no disc capacitor datasheet and no disc capacitor stock on the date we last checked, which is exactly why we say so rather than imply a shelf that is not there.

What should a buyer in the Netherlands do about two shelves that never overlap?

Specify the X1 voltage before the capacitance, because the capacitance is the field that misleads you. A 230 V Dutch mains design most often calls for Y2 at 250 Vac on the Y side, which both shelves can technically carry — but only the disc shelf can reach the 440 Vac X1 rating that many mains filter designs specify, and only the chip shelf can go into a reflow oven. The trade press has reported passive component lead times stretching through 2026 as AI server and electric vehicle programmes draw on the same ceramic capacity, so identifying the right shelf early, rather than after a BOM import fails silently, is worth the ten minutes.

1. Write down the X1 voltage and the Y class separately before you search. “250 Vac Y2” is a requirement; “100 pF” is not.
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, and use the safety-certified filter to see both shelves’ candidates stated field by field, differences included.
3. Check what is physically in Hong Kong on ready stock before you commit to a slot — 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 certificate sits on a page of a datasheet we will send you, not behind an adjective.

For the class distinction behind this post, see X1/Y1 vs X1/Y2 safety capacitors. For what the disc export’s own rating column does and does not parse, see the disc capacitor UR column holds two incompatible rating systems. The ranges sit on the Walsin disc capacitor and Walsin MLCC pages.

The short version

A Y capacitor safety selection between Walsin’s disc shelf and chip S2 shelf mismatches on nine of ten fields we checked. The two shelves share 26 of 36 capacitance values, which is more overlap than most selectors assume, but they share zero X1 voltage ratings — the chip ceiling of 310 Vac sits below the disc floor of 400 Vac, and Y1 class exists only on the disc side. The chip shelf gives you a reflow footprint and a certificate on a page we hold; the disc shelf gives you every X1 rating from 400 to 760 Vac and the only Y1 option in the catalogue. Neither shelf is complete on its own. Qualification stays with you.

Send us your Y capacitor requirement with the X1 voltage and the Y class stated separately, and we will come back with candidates from both shelves, field by field, blanks included — and tell you plainly which one is actually in Hong Kong today.

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Frequently asked questions

<!– wp:rank-math/faq-block {"questions":[{"id":"faq-question-01","title":"Can a chip S2 safety capacitor replace a disc safety capacitor at 440 Vac X1?","content":"No. The chip S2 shelf's real working rating, per Walsin's own approval sheet, is X1 310 Vac under UL and TUV and 250 Vac under CQC — below every X1 rating the disc shelf offers, which starts at 400 Vac. We read this directly from 16_Safety_X1Y2_General_S2.pdf rather than from the export, which only states the impulse voltage.”,”visible”:true},{“id”:”faq-question-02″,”title”:”How much do the disc and chip S2 shelves overlap on capacitance?”,”content”:”26 of 36 distinct capacitance values appear on both shelves, covering 309 of the 367 disc safety rows and 150 of the 173 chip rows. We matched the two exports value by value to get this figure, and we have not seen it counted anywhere else.”,”visible”:true},{“id”:”faq-question-03″,”title”:”Does Walsin offer a Y1-class chip safety capacitor?”,”content”:”Not in anything we hold. All 173 rows of the chip S2 export are Y2 class. The Y1 class exists only on the disc shelf, across 181 of its 367 safety rows, in the AH and AS series.”,”visible”:true},{“id”:”faq-question-04″,”title”:”Why does the chip S2 export show 5000 Vdc instead of a working voltage?”,”content”:”Because that field is the impulse voltage, not the working voltage. The approval sheet states the real rating as X1 310 Vac, Y2 250 Vac and 1500 Vdc under UL and TUV, and 250 Vac under CQC — figures that appear nowhere in the 173-row export.”,”visible”:true},{“id”:”faq-question-05″,”title”:”Does Venatech hold a disc capacitor datasheet?”,”content”:”No. We hold 28 Walsin datasheets, 451 pages, covering 26 MLCC series and 2 chip resistor series. None of them is a disc capacitor sheet, so every disc figure in this post is the export’s own text, not a datasheet-confirmed rating.”,”visible”:true},{“id”:”faq-question-06″,”title”:”Are either of these safety capacitor shelves in Hong Kong stock right now?”,”content”:”Only the chip shelf, and only three part numbers — S242B102K502, S252B222K502 and S252B471K502ZT — as at the 23 September 2026 snapshot. None of the 367 disc safety rows is on that snapshot, so the disc shelf is an order-in line today.”,”visible”:true},{“id”:”faq-question-07″,”title”:”What is the fastest way to cross a Y capacitor requirement across both shelves?”,”content”:”State the X1 voltage and the Y class before the capacitance, then paste your BOM into the free cross-reference tool and filter for safety certified. It is matched against Walsin’s published catalogue and returns candidates from both shelves with every difference stated, not hidden.”,”visible”:true}],”listStyle”:””,”titleWrapper”:”h3″,”titleCssClasses”:””,”contentCssClasses”:””,”sizeSlug”:””} –>

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