MLCC DC Bias Derating: Four Columns With Headers and Zero Data

DC Bias 25, TCC, Packing and SPQ are four column headers in Walsin’s enriched MLCC export, and zero of 173 rows fill any of them. MLCC DC bias derating is decided by whichever column was meant to carry it, and it carries nothing. We will not invent a derating percentage to fill the gap.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds 00_ALL_MLCC_combined.xlsx, the 24,026-row main MLCC export, and Walsin Technology (Walsin)’s own 12-page 00_MLCC_Application_Guide.pdf. Every count below came from opening those three files ourselves, cell by cell and page by page, and every part number is real.

How many of the 173 enriched MLCC rows fill their DC Bias, TCC, Packing or SPQ column?

Zero. We checked all 173 rows of 00_ALL_MLCC_combined.xlsx against all four columns: TCC, DC Bias 25, Packing and SPQ are declared headers with not one filled cell between them.

Column	Rows filled out of 173	What it would decide
Dimensions, Capacitance, Rated Voltage	173 (100%)	Baseline selection
IR, DF	18 (10.4%)	Leakage current, self-heating
TCC	0 (0%)	Temperature coefficient of capacitance
DC Bias 25	0 (0%)	Capacitance loss at 25 V or 25 °C, header does not say which
Packing	0 (0%)	Reel size, tape or bulk
SPQ	0 (0%)	Standard pack quantity, order rounding

This is the file Walsin’s own export already labels “enriched” with seven fields the main 24,026-row export does not carry at all. Four of those seven arrived as headers only. We have not seen that measured anywhere before.

Which rows actually need a DC bias figure, and which do not?

A hundred and one of 173. We split the 173 rows by dielectric: NP0 and X8G are Class I ceramics whose capacitance does not fall under applied DC voltage, while X7R, X5R and X6S are Class II and do. We counted 101 Class II rows (58.4%) against 72 Class I rows (41.6%). The DC Bias 25 column is empty on every single one of the 101 rows where the figure would actually matter.

Part number	Dielectric	Capacitance	DC Bias 25 published?	Match / mismatch vs “Class II rows need a DC bias figure”
MT15N0R5C500	NPO	0.5 pF	No	Match — Class I, figure correctly not needed
HH15N0R5C500	NPO	0.5 pF	No	Match — Class I, figure correctly not needed
01R5N100J160	NPO	10 pF	No	Match — Class I, figure correctly not needed
MG15B101J160	X7R	100 pF	No	Mismatch — Class II, no figure published
ST18B473K500	X7R	47 nF	No	Mismatch — Class II, no figure published
0201X101K160	X5R	100 pF	No	Mismatch — Class II, no figure published
TT31X225K100	X5R	2.2 µF	No	Mismatch — Class II, no figure published

The column is not simply incomplete — it is uninformative in a specific way. A buyer filtering on “DC Bias 25” cannot tell a Class I part that correctly has nothing to report from a Class II part that needs the figure and does not have it.

Does Walsin’s own application guide publish a DC bias derating curve?

No. We opened 00_MLCC_Application_Guide.pdf and searched the full extracted text of all 12 pages, 15,611 characters, for the word “bias”. It appears zero times. “Derating” appears once, in a sentence about reliability: “Voltage derating will greatly reduce the failure rate, since the failure rate follows the 3 power law.” That is a lifetime-versus-voltage statement, not a capacitance-versus-voltage curve.

What is the honest method for DC bias derating without a published figure?

Treat rated capacitance as a ceiling, not a working value, on any Class II part — and go to the manufacturer for the number rather than a rule of thumb. Class II dielectrics (X7R, X5R, X6S) are ferroelectric: their permittivity falls as the electric field across the dielectric rises, so applying DC voltage reduces real capacitance below the marked value, more on a thin dielectric at high field than on a thick one at the same voltage. NP0 and X8G do not do this.

We are not going to give you a percentage, because we checked for one in the two files we hold that could carry it — the export and the application guide — and found neither. We have not seen this absence stated plainly before, and the honest version of the method is:

1. Identify whether the part is Class I or Class II from the dielectric code — see NP0 vs X7R vs X5R: which MLCC dielectric. Only Class II needs the next steps.
2. Request the bias curve for the exact part number from Walsin, not a series-level estimate. Case size, dielectric and rated voltage all move the curve.
3. Measure at your working voltage if the curve is not available, rather than trust the marked value at your working point.
4. Specify headroom on rated voltage as a separate decision from bias, because reliability derating and DC bias derating are two different reductions for two different reasons — confusing them is how a design ends up with enough voltage margin and too little real capacitance, or the other way round.

Why are Packing and SPQ empty on every one of the 173 rows too?

Because the gap is not specific to DC bias. We checked Packing and SPQ the same way: zero of 173 rows carry either. Both already read empty on all 24,026 rows of the main MLCC export, a defect banked elsewhere in this corpus — what we are adding here is that the 173-row file built specifically to enrich the export with extra fields inherited the same two blanks rather than fixing them. Packing decides whether a part ships on 7-inch or 13-inch reel, paper or plastic carrier, or in bulk; SPQ decides the quantity your order rounds up to. Neither is answerable from any export we hold, for any of the 23,601 distinct MLCC part numbers.

What should you request from Walsin before you specify a Class II MLCC?

The part-specific DC bias curve, in writing, before the part goes on a BOM that cannot tolerate a capacitance shortfall. Everything else in this file — dimensions, tolerance, rated voltage, even insulation resistance on 18 rows — is a published, checkable figure. DC bias derating on a Class II part is not, and treating a blank cell as “no derating” is the error this post exists to head off.

1. Tell us the dielectric and case size and we will tell you honestly whether we hold any bias data for it — on the current evidence, we do not, for any Walsin MLCC part.
2. Cross the rest of your BOM while you wait on the curve. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool, which decodes 18 manufacturers’ part numbers against 800,000+ crossable Walsin part numbers and states every difference field by field, blanks included.
3. Check Hong Kong stock on ready stock, a dated snapshot as at 23 September 2026, before committing a production slot to a part whose bias behaviour is still unconfirmed.

The short version

Four column headers in Walsin’s enriched MLCC export — TCC, DC Bias 25, Packing, SPQ — carry zero filled cells across all 173 rows, and 101 of those rows are Class II dielectrics for which a DC bias figure is not optional. Walsin’s own 12-page application guide does not contain the word “bias” once. We will teach the method — identify Class I versus Class II, request the part-specific curve, measure if you must — and we will not invent the number that fills the gap.

Send us the dielectric, case size and rated voltage on your Class II positions, and we will tell you plainly whether a bias curve exists for that part — then cross the rest of the BOM with us while you wait on the answer. For the general derating framework, see MLCC DC bias and voltage derating. The full range is on the Walsin MLCC page.

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Frequently asked questions

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