Microwave MLCC Compared: Walsin UF vs RF vs HH Series

Walsin’s UF series is a narrow-tolerance microwave MLCC line, offering ±0.02 pF and ±0.03 pF
tolerances that neither the RF nor the HH microwave series publish. All three are NP0, high-Q,
low-ESR MLCC built for RF and microwave circuits, and share one data quirk: 38 of the 24,025
MLCC rows in Walsin’s export write the Tolerance field with a unicode ± symbol instead of the
catalogue’s standard +- text, and every one of those 38 belongs to either RF or UF.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the full MLCC parametric
extract from Walsin Technology (Walsin) — 24,025 real parts across 16 series — and the UF, RF and
HH datasheet PDFs. Every part number below is real.

What is Walsin’s UF series, and how does it differ from RF and HH?

UF (“Microwave MLCC with Narrow-Tolerance”) is 285 real parts, 0201 and 0402 only, NP0 only,
25V-100V. Its defining feature, stated on the datasheet’s own cover page, is “ultra-narrow
tolerance of capacitance” down to ±0.02 pF. RF and HH are Walsin’s other two NP0 microwave lines
— larger in part count and case-size range, but neither publishes a tolerance tighter than
±0.05 pF.

UF is the smallest of the three by part count and the narrowest by case-size range, but it is the
only one of the three whose ordering key defines a P (±0.02 pF) or Q (±0.03 pF) tolerance
code at all.

Field by field, where do UF, RF and HH actually match or mismatch?

At a shared electrical point — 0402, 1.0 pF, ±0.05 pF, 50Vdc — all three series publish a part,
and the published dimensions are identical.

The three parts are identical on every field the parametric export carries at this capacitance
point. What separates them is not in this table at all — it is how far each series’ tolerance and
voltage range extends beyond this one shared point, which only shows up once you look at the
full series rather than a single row.

Is there a formatting quirk shared across the three microwave series?

Yes. 38 of the 24,025 MLCC rows in Walsin’s export write the Tolerance field using a unicode
± character instead of the catalogue’s standard +- ASCII pair — and all 38 sit in RF (26) or
UF (12). HH carries none.

Example rows: UF03N1R2Q101 and UF03N1R2Q500 both read ±0.03pF, where every other UF row
reads +-0.05pF, +-0.1pF or similar with the ASCII pair. On the RF side, RF03N1R1D500 and
RF03N2R2D500 show the same pattern, reading ±0.5pF. A text filter searching for +- as a
literal string would silently skip all 38 of these otherwise-normal rows.

What case sizes and voltages does UF actually cover?

Two case sizes only — 0201 (206 parts) and 0402 (79 parts) — and three voltage steps: 25Vdc
(60 parts), 50Vdc (147) and 100Vdc (78). RF and HH both reach larger case sizes and wider voltage
ranges.

If a design needs this narrow-tolerance capability beyond 0402, or beyond 100V, UF does not have
it — the next step up is RF or HH in the same NP0 dielectric, at a wider but less precise
tolerance. See
High Q, low ESR MLCC for RF for the broader RF-design
selection criteria across all three of Walsin’s microwave MLCC series.

Which of the three should I specify for a narrow-tolerance RF design?

Start from the tolerance you actually need, then check whether the case size and voltage fit.

• Capacitance must hold within ±0.02 pF or ±0.03 pF. UF only — neither RF nor HH publishes a
  P or Q tolerance code. Limited to 0201/0402 and 25V-100V.
• Standard RF tolerance, ±0.05 pF or looser, and a case size or voltage UF does not cover.
  RF or HH. RF reaches down to 01R5 and up to 1111, and up to 1,500Vdc; HH tops out at 0805 and
  630Vdc.
• X8G dielectric for stable high-reliability RF. RF only — it is the sole one of the three
  that offers an X8G option (104 of its 3,615 parts), alongside its NP0 majority.
• Second-sourcing an existing RF design against an incumbent narrow-tolerance part. Compare
  the incumbent’s datasheet against all three series field by field; a tolerance and case size
  match does not guarantee Q, ESR or other RF-specific figures match, and those are not in the
  parametric export at all.

For general tolerance and dielectric code decoding across Walsin’s MLCC range, see
Tolerance, TCR and dielectric codes decoded.

Can I substitute a UF part with an RF or HH part at the same capacitance?

Not without checking tolerance and the fields outside the parametric export. At 0402, 1.0 pF,
±0.05 pF, 50Vdc the three series publish identical dimensions, so a substitution at that specific
point is supported by the data we hold. Move to a tighter tolerance and only UF answers it; move
to a case size or voltage outside UF’s range and only RF or HH answers it.

None of the three parametric exports carries Q factor or ESR directly — both are in the
datasheets, not the export — so a substitution based on the five selection fields alone does not
confirm RF performance. Read the specific datasheet page for Q and ESR before substituting across
series.

The short version

UF, RF and HH are Walsin’s three NP0 microwave MLCC series. UF is the narrowest by tolerance
(down to ±0.02 pF) and the smallest by case-size range (0201/0402 only, 25V-100V); RF is the
largest by part count and case-size span; HH sits between them. All three publish identical
dimensions at a shared electrical point like 0402/1.0 pF/±0.05 pF/50Vdc, and RF and UF together
carry 38 rows where the Tolerance field uses a unicode ± symbol instead of the catalogue’s
standard text — a pattern HH does not share.

Send us your tolerance, case size and voltage requirement, and we will tell you which of UF,
RF or HH actually answers it, with the part number and datasheet page. Or give us one part
number and ask us to cross it. The full range is on the
Walsin MLCC range page.

Two things you can do without waiting for a reply. Cross your part — paste a single number or drop in an Excel or CSV of the whole line, and each result names what matches and what does not. And ready stock lists the ceramic capacitor part numbers held in Hong Kong, with an RFQ against any of them.

Frequently asked questions