MT is Walsin Technology (Walsin)’s automotive MLCC series qualified to AEC-Q200, with
2,176 part numbers. MG is the automotive series without AEC-Q200 certification, at 788
parts. ST adds soft termination under AEC-Q200, at 118 parts. If your programme requires
AEC-Q200 on passives, an MG part cannot satisfy that line.
What is the difference between the Walsin MT and MG series?
The qualification carried by the family. MT is qualified to AEC-Q200 and is the series to
quote when a customer specification, a PPAP submission or an IATF-governed BOM requires
it. MG is Walsin’s automotive line without that certification. Both are automotive series;
only one carries the document.
Walsin names the two series explicitly in its own catalogue data: “Automotive Caps
Qualified to AEC-Q200 (MT series)” and “Automotive Caps Without AEC-Q200 Certification
(MG series)”. That naming is unusually direct, and it removes the ambiguity that normally
surrounds automotive-grade claims. There is no inference to make.
The series datasheets are separate documents:
MT series
and
MG series.
Can I use an MG part where AEC-Q200 is specified?
No. AEC-Q200 is a qualification applied to a part family and evidenced by documentation.
It is not a performance grade you can argue your way into by comparing datasheets. If the
requirement on the line is AEC-Q200, the answer is an AEC-Q200 part: MT, or ST where soft
termination is also required.
This catches teams at the worst moment, during a customer audit or a PPAP review, long
after the board is in production. The part may perform perfectly. The line still fails,
because the evidence package does not exist for that family.
Where MG legitimately belongs is automotive-adjacent work that does not carry the
requirement: aftermarket accessories, diagnostic equipment, test fixtures and industrial
builds. Decide that at specification time, and record which series each line calls for.
Compare six real automotive parts field by field
These are not like-for-like substitutes and the table does not present them as such. The
reference is MT15N100F250. The right-hand column states exactly which fields match and
which do not.
| Walsin part number | Series | Qualification | Size | Dielectric | Capacitance | Tolerance | Rated voltage | Match / mismatch vs MT15N100F250 |
|---|---|---|---|---|---|---|---|---|
| MT15N100F250 | MT | AEC-Q200 | 0402 | NPO | 10 pF | ±1% (code F) | 25 Vdc | reference part |
| MT15N100F160 | MT | AEC-Q200 | 0402 | NPO | 10 pF | ±1% (code F) | 16 Vdc | match: series, qualification, size, dielectric, capacitance, tolerance · mismatch: 16 Vdc not 25 Vdc |
| MT15N100F100 | MT | AEC-Q200 | 0402 | NPO | 10 pF | ±1% (code F) | 10 Vdc | match: series, qualification, size, dielectric, capacitance, tolerance · mismatch: 10 Vdc not 25 Vdc |
| MT15N0R5C500 | MT | AEC-Q200 | 0402 | NPO | 0.5 pF | ±0.25 pF (code C) | 50 Vdc | match: series, qualification, size, dielectric · mismatch: 0.5 pF not 10 pF, absolute tolerance not percentage, 50 Vdc |
| MG15B101J500 | MG | none | 0402 | X7R | 100 pF | ±5% (code J) | 50 Vdc | match: size, 1.00 × 0.50 × 0.50 mm body · mismatch: no AEC-Q200, X7R not NPO, 100 pF, ±5%, 50 Vdc |
| MG15B102J160 | MG | none | 0402 | X7R | 1000 pF | ±5% (code J) | 16 Vdc | match: size, 1.00 × 0.50 × 0.50 mm body · mismatch: no AEC-Q200, X7R not NPO, 1000 pF, ±5%, 16 Vdc |
| ST18B473K500 | ST | AEC-Q200 | 0603 | X7R | 47 nF | ±10% (code K) | 50 Vdc | match: AEC-Q200 qualification · mismatch: 0603 not 0402, soft termination, X7R not NPO, 47 nF, ±10%, 50 Vdc |
Sources:
MT series datasheet,
MG series datasheet,
ST series datasheet
All four MT parts and both MG parts share the same 0402 body: 1.00 ±0.05 mm long,
0.50 ±0.05 mm wide, 0.50 ±0.05 mm thick. The mechanical footprint is identical. Everything
electrical, and the qualification, is not.
Which dielectrics does each series cover?
MT is NPO-weighted. Of its 2,176 parts, 1,283 are NPO and 889 are X7R, with three X8G
parts for high-temperature work. MG is X7R-weighted: 414 X7R, 344 NPO and 30 X5R out of
788. MT offers X8G; MG offers X5R. Neither offers the other’s outlier.
| Dielectric | MT (AEC-Q200) | MG (no certification) |
|---|---|---|
| NPO | 1,283 | 344 |
| X7R | 889 | 414 |
| X5R | — | 30 |
| X8G | 3 | — |
That X5R row deserves a note. If your MG line is one of those 30 X5R parts, there is no
X5R option in MT, so an AEC-Q200 requirement forces a dielectric change as well as a
series change. X5R stops at +85 °C; X7R runs to +125 °C.
Is there an MT part for every MG part?
No, and you should not assume a one-for-one path exists. The catalogue data we hold does
not contain a pair of MT and MG parts matching on case size, dielectric, capacitance,
tolerance and rated voltage at the same time. Moving a line from MG to MT is a selection
exercise, not a relabelling exercise.
Work the fields in order. Fix the case size. Fix the dielectric, checking the temperature
ceiling the circuit needs. Fix the capacitance and confirm it after DC bias, not from the
marked value. Then take the tightest tolerance and the highest voltage rating available at
that combination. Whatever is left over is the compromise, and it should be written down.
The same discipline applies in reverse. An MG part chosen because MT did not carry the
value is a deliberate decision to drop the qualification. Record it at design review
rather than discovering it at audit.
When would I choose ST over MT?
When the board bends. ST is the AEC-Q200 soft-termination series, and its conductive
polymer termination layer absorbs board flex that would otherwise crack the ceramic. Both
MT and ST satisfy an AEC-Q200 line item. ST additionally addresses mechanical stress. It
is a much narrower range at 118 parts.
Use ST where the mechanical environment justifies it: near board edges, near mounting
screws, on large boards, on modules that see vibration, and on anything depanelled by
breaking rather than routing. Use MT where the mechanical risk is low and you need the
range — 2,176 parts against 118 is a very large difference in what you can actually find.
If a value exists only in MT and the location is mechanically exposed, the fallback is
layout: orient the part across the bend axis, increase clearance from the edge and the
mounting hole, and review the depanelling method.
How many automotive MLCC parts does Walsin actually have?
2,176 in MT, 788 in MG and 118 in ST, counted from the parametric data rather than from a
published figure. The dielectric breakdowns reconcile exactly to those totals, which is
how we know the counts are complete rather than truncated.
Counting from the data matters more than it sounds. Walsin’s own product counter includes
the header row on some product lines: the site reports 380 varistors, and there are 379
real parts. It is a one-part error and harmless on its own. It is also a reason to verify
any published count before a sourcing decision rests on it. Venatech Limited, an
authorised Walsin distributor in Hong Kong, counts from the exported rows and reconciles
them against the series datasheets.
Frequently asked questions
What does AEC-Q200 actually qualify?
AEC-Q200 is the automotive stress test qualification for passive components. It defines a test suite covering temperature cycling, humidity, mechanical shock, vibration, board flex and operational life, and it is applied to a part family. The evidence is documentary. It cannot be inferred from a datasheet comparison.
Is the MG series lower quality than MT?
That is not the distinction Walsin draws. MG is named in the catalogue as the automotive series without AEC-Q200 certification. The difference stated by the manufacturer is the certification, not a quality grade. Compare the two datasheets field by field for the specific parameters your design depends on.
Does MT cover high-temperature applications above +125 °C?
There are three X8G parts in the MT series. X8G is a Class I dielectric rated to +150 °C. Three parts is a very narrow selection, so confirm the value, case size and voltage you need exists before designing around it. Work from the MT datasheet.
Can I mix MT and MG on the same board?
Technically yes, but only if the programme requirement allows it line by line. Some customer specifications require AEC-Q200 on every passive; others apply it only to safety or powertrain circuits. Record which lines carry the requirement, and do not let an MG part drift onto a line that needs MT.
Which is the larger series, MT or ST?
MT, by a wide margin: 2,176 parts against 118. Both are AEC-Q200 qualified. ST is the soft-termination line and is narrow because it is a specialist construction. Start from MT for range and move to ST when board flex is a real mechanical risk at that location.
Do I need soft termination for an automotive design?
Not automatically. It depends on the mechanical environment at that location, not on the application sector. Board size, mounting method, connector forces, depanelling and vibration decide it. Where those risks are present, ST gives you soft termination and AEC-Q200 in the same part.
Next step
If you have an automotive BOM with ceramic lines chosen before the qualification
requirement was pinned down, that is the BOM to send us. Venatech Limited will mark every
line against MT, MG and ST, state which ones carry AEC-Q200, and return a field-by-field
comparison with matches and mismatches written out. Where no Walsin part matches on every
field we will say so and show you which field gives way. Ask us to cross a part and you
get the differences, not a claim of sameness.
Send us your BOM → · Browse Walsin MLCC →
Related reading: Soft termination MLCC: SH, SG, ST and VT ·
NP0 vs X7R vs X5R: which MLCC dielectric
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.