Walsin’s soft termination MLCCs put a conductive polymer layer between the ceramic and
the outer termination to absorb board flex. SH uses silver-polymer and is the broadest
range at 1,524 parts. SG uses copper-polymer, 65 parts. ST is the AEC-Q200 automotive
soft-termination series, 118 parts. VT is datasheet-only.
What is a soft termination MLCC and when do I need one?
A soft termination MLCC has a compliant conductive polymer layer inside the termination
stack. Board bending transfers stress into the termination rather than into the ceramic
body. That prevents flex cracks, which are the dominant mechanical failure mode for
ceramic capacitors on large boards.
You need one when the board moves. Depanelling, connector insertion, press-fit operations,
screw-down mounting, a large board with mounting points far apart, or a module that sees
vibration in service. All of these bend the PCB under the capacitor. A standard
termination transmits that bend straight into a brittle dielectric.
Flex cracks are unpleasant because they often do not fail open. They fail as a leakage
path that grows, so the board passes test and fails in the field. That is why many
automotive and industrial programmes specify soft termination by policy rather than
assessing it board by board.
What is the difference between SH, SG, ST and VT?
Termination chemistry and qualification. SH is silver-polymer and is the general-purpose
soft termination line. SG is copper-polymer. ST is soft termination qualified to AEC-Q200
for automotive. VT is the soft-termination series built against VW80808 and exists only as
a datasheet in Walsin’s published data.
| Series | Termination | Qualification | Parts in our data | Datasheet |
|---|---|---|---|---|
| SH | Silver-polymer (Ag-poly) | General purpose | 1,524 | SH datasheet |
| SG | Copper-polymer (Cu-poly) | General purpose | 65 | SG datasheet |
| ST | Soft term, automotive | AEC-Q200 | 118 | ST datasheet |
| VT | Soft term, automotive | VW80808 | 0 in the parametric data | VT datasheet |
The part count column is the one that changes a sourcing decision. SH is more than twenty
times the size of SG. If you have written “soft termination” on a BOM line without naming
a series, SH is where the value and voltage combination you need is most likely to exist.
Compare five real soft termination parts field by field
All five are 0603 or 0805 X7R. The reference is SH18B101K101. The right-hand column states
what matches and what does not, field by field.
| Walsin part number | Series | Size | Capacitance | Tolerance | Rated voltage | L × W × T (mm) | Match / mismatch vs SH18B101K101 |
|---|---|---|---|---|---|---|---|
| SH18B101K101 | SH, Ag-poly | 0603 | 100 pF | ±10% | 100 Vdc | 1.60 ±0.20 · 0.80 ±0.10 · 0.80 ±0.07 | reference part |
| SH18B101K160 | SH, Ag-poly | 0603 | 100 pF | ±10% | 16 Vdc | 1.60 ±0.20 · 0.80 ±0.10 · 0.80 ±0.07 | match: series, size, capacitance, tolerance, all three dimensions · mismatch: 16 Vdc not 100 Vdc |
| SG18B102K500 | SG, Cu-poly | 0603 | 1000 pF | ±10% | 50 Vdc | 1.60 ±0.20 · 0.80 ±0.10 · 0.80 ±0.07 | match: size, tolerance, all three dimensions · mismatch: copper-polymer not silver-polymer, 1000 pF, 50 Vdc |
| SG18B104K500 | SG, Cu-poly | 0603 | 100 nF | ±10% | 50 Vdc | 1.60 ±0.30 · 0.80 ±0.30 · 0.80 ±0.30 | match: size, tolerance, nominal dimensions · mismatch: copper-polymer, 100 nF, 50 Vdc, wider ±0.30 tolerance on all three dimensions |
| ST18B152K500 | ST, AEC-Q200 | 0603 | 1500 pF | ±10% | 50 Vdc | 1.60 ±0.20 · 0.80 ±0.10 · 0.80 ±0.07 | match: size, tolerance, all three dimensions · mismatch: AEC-Q200 qualified, 1500 pF, 50 Vdc |
| ST21B104K500 | ST, AEC-Q200 | 0805 | 100 nF | ±10% | 50 Vdc | 2.00 ±0.20 · 1.25 ±0.10 · 1.25 ±0.10 | match: tolerance, X7R · mismatch: 0805 footprint, AEC-Q200 qualified, 100 nF, 50 Vdc, 1.25 mm thick |
Sources: SH datasheet,
SG datasheet,
ST datasheet
Look at the dimensional tolerance column rather than the nominal dimensions. SG18B104K500
and ST18B473K500 both carry ±0.30 mm on length, width and thickness, while the lower-value
parts in the same series hold ±0.20, ±0.10 and ±0.07. On a fine-pitch layout with a tight
courtyard, the high-value parts in these series need more clearance than their nominal
0603 size suggests.
Is copper-polymer SG better than silver-polymer SH?
Neither is better in general. They are different termination chemistries with different
process and cost characteristics, and Walsin lists them as separate series rather than as
grades of one another. The decisive difference for a designer is range: SH offers 1,524
parts, SG offers 65.
Practically, treat SG as a selection made for a specific process reason and SH as the
default when a design simply needs soft termination. If a customer specification names
copper-polymer, the 65-part SG range is where to look, and the value you need may not be
in it.
Do I need the ST series if my design is automotive?
If the programme requires AEC-Q200 on passives, yes — the qualification is the
requirement, not the termination. ST is Walsin’s soft-termination line qualified to
AEC-Q200, with 118 parts. SH and SG are soft-terminated but are not carried under that
qualification, so they will not satisfy an AEC-Q200 line item.
ST18B473K500 decodes as ST series, 0603, X7R, 47 nF, ±10%, 50 Vdc. ST21B104K500 is the
0805, 100 nF, ±10%, 50 Vdc part. Full series data is in the ST datasheet —
https://www.passivecomponent.com/wp-content/uploads/datasheet/WTC_MLCC_Soft_term_Auto_AECQ200_ST.pdf
A hundred and eighteen parts is a narrow range for an automotive BOM. If ST does not carry
your value, the choice is the wider AEC-Q200 MT series plus mechanical mitigation on the
board: orient the part across the bend, keep it clear of board edges and mounting holes,
and review the depanelling method.
Why does the VT series return nothing on Walsin’s search?
Because it is not indexed. VT is one of six MLCC series that return zero parts on Walsin’s
own parametric search tool. The datasheet exists and the series is real. The parametric
data simply is not there, so a search-driven selection process concludes the series does
not exist.
The six are VT, 0612, OP, S3, SG High Voltage and SH High Voltage. Two of those are
directly relevant to anyone reading this page: the high-voltage variants of both SH and SG
are invisible on Walsin’s search. If you searched for a soft-terminated high-voltage part,
found nothing, and moved to another manufacturer, you may have been reading an indexing
gap rather than a catalogue gap.
This is not published anywhere. We found it by exporting every MLCC series in turn and
recording which ones came back empty. Venatech Limited, an authorised Walsin distributor
in Hong Kong, works from the datasheets for those six series and can confirm what exists
against the drawing and ordering tables directly. The VT datasheet is here —
https://www.passivecomponent.com/wp-content/uploads/datasheet/WTC_MLCC_Soft_term_Auto_VW80808_VT.pdf
Does soft termination change the footprint or the reflow profile?
The land pattern is the standard pattern for the case size. The dimensions above show why
that needs checking on high-value parts: the ±0.30 mm dimensional tolerance on some SG and
ST lines is wider than the ±0.10 and ±0.07 mm on the low-value parts in the same series.
Reflow limits come from the individual series datasheet.
Do not assume that soft termination removes the need for good mechanical practice. It
raises the bend the part survives; it does not make the part immune. Orientation relative
to the bend axis, distance from the board edge, and the depanelling method still matter.
Frequently asked questions
What is a flex crack?
A crack in the ceramic body caused by the board bending under the mounted part. It typically starts at the termination and runs into the dielectric. It often does not cause an immediate open circuit; it creates a leakage path that degrades over time, which is why flex cracks escape production test and appear as field failures.
Which Walsin soft termination series has the widest range?
SH, the silver-polymer series, with 1,524 part numbers in our data. SG has 65 and ST has 118. If your BOM line says only “soft termination” with no series named, start with SH and check the value, voltage and case size you need against the SH datasheet.
Can I use SH where a specification calls for AEC-Q200?
No. SH is soft-terminated but is not carried under AEC-Q200 qualification. The ST series is Walsin’s AEC-Q200 soft-termination line. Qualification is a documentation requirement on the part family and cannot be inferred from the construction.
Where should I place soft termination parts on a board?
Away from board edges, mounting holes and depanelling breakouts, and oriented so the long axis of the part runs across the bend rather than along it. Soft termination increases the bend the part tolerates. Layout decides how much bend the part actually sees.
Does Walsin offer high-voltage soft termination parts?
There are SH High Voltage and SG High Voltage series. Both return zero parts on Walsin’s parametric search, so no downloadable data exists for them. The series are real. Confirm the available values and ratings against the datasheets rather than the search tool.
Is VT the same as ST?
They are different series. ST is qualified to AEC-Q200. VT is built against VW80808, a different automotive requirement, and has no parametric data published. Confirm which standard your programme requires before selecting, and work from the VT datasheet if that is the one named.
Next step
If your board bends and your BOM does not say soft termination anywhere, that is worth an
hour before the next build. Send your BOM to Venatech Limited and we will mark the Class
II lines where flex is a realistic risk, identify which Walsin soft termination series
carries the value and rating, and return a field-by-field comparison with matches and
mismatches stated. For the six series with no parametric data we work from the datasheets
and tell you plainly what we could and could not confirm.
Send us your BOM → · Browse Walsin MLCC →
Related reading: How to read a Walsin MLCC part number ·
AEC-Q200 MLCC: MT vs MG series
Cross it yourself. The cross-reference tool takes a single part number or a whole BOM column and returns the Walsin candidates with every field that differs stated plainly — qualification stays with you. Ready stock shows what is held in Hong Kong today, with an RFQ against any line.