Walsin Technology (Walsin) builds its tantalum nitride thin film resistors as the MF
series. Venatech holds 20,520 MF parts. Every one is 1206 (3216) and every one is rated
2/5 W. The series is 1,026 resistance values from 10 Ω to 1 MΩ, times five tolerance grades
from ±0.05% to ±1%, times four TCR grades from ≦±10 to ≦±50 ppm/°C.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin’s parametric
export for the thin film range. Every count below is measured from that extract.
Flagged for review. We hold no public datasheet URL for the Tantalum Nitride Thin Film
Chip Resistor / MF Series. It is cited by series name throughout this post. Confirm the
public PDF address with Walsin before publishing.
What is a tantalum nitride thin film resistor?
A chip resistor whose resistive element is a sputtered tantalum nitride film rather than a
nickel chromium film or a ruthenium oxide thick film paste. The film forms its own passivating
surface oxide, which is why the technology is chosen where humidity and long-term drift
matter.
Construction is otherwise conventional: alumina substrate, sputtered film, laser trim,
protective overcoat, three-layer termination. What changes is the film chemistry.
Flagged for review. The self-passivating oxide mechanism above is the generally
understood reason tantalum nitride is specified, not a quoted Walsin claim. Venatech does
not hold a Walsin statement of humidity performance for the MF series. Do not put a
numeric moisture specification in a design review until Walsin confirms it.
What case sizes and power ratings does the Walsin MF series come in?
One of each. All 20,520 MF parts in Venatech’s extract are 1206 (3216), and all 20,520 are
rated 2/5 W. There is no 0402 MF part, no 2512 MF part, no 1/4 W MF part and no 1 W MF part.
The series is a single footprint at a single power rating.
Unique to Venatech’s data. Every one of the 20,520 Walsin tantalum nitride MF parts is
1206 (3216) and every one is rated 2/5 W. One size, one power, 20,520 combinations of
resistance, tolerance and TCR. By contrast Walsin’s WF precision thin film series spreads
58,314 parts across eight case sizes and ten power ratings. This single-footprint
concentration is not stated on any Walsin summary page; it only appears when the export is
counted.
2/5 W is itself unusual. Not one of the 234,815 thick film chip resistor rows Venatech holds
carries it. In the thin film catalogue it appears twice: on the 5,039 WF parts at 1210 and on
all 20,520 MF parts at 1206. A BOM filter written to accept 1/4 W or 1/2 W at 1206 silently
excludes the entire MF series.
What tolerance and TCR grades does the MF series offer?
Five tolerances and four TCR grades, fully crossed. Tolerance runs ±0.05%, ±0.1%, ±0.25%,
±0.5% and ±1%, at 4,104 parts each. TCR runs ≦±10, ≦±15, ≦±25 and ≦±50 ppm/°C, at 5,130
parts each. Every tolerance is available at every TCR grade.
| Grade | Parts held | Available at every TCR grade | Match / mismatch vs WF thin film |
|---|---|---|---|
| ±0.05% tolerance | 4,104 | Match — all four | Mismatch — WF has no ±0.05% grade |
| ±0.1% tolerance | 4,104 | Match — all four | Match — WF offers ±0.1% at 0201 only |
| ±0.25% tolerance | 4,104 | Match — all four | Mismatch — WF has no ±0.25% grade |
| ±0.5% tolerance | 4,104 | Match — all four | Match — WF offers ±0.5% at 0201 only |
| ±1% tolerance | 4,104 | Match — all four | Match — WF offers ±1% at 0201 only |
| ≦±10 ppm/°C TCR | 5,130 | — | Match — WF offers ≦±10 |
| ≦±15 ppm/°C TCR | 5,130 | — | Match — WF offers ≦±15 |
| ≦±25 ppm/°C TCR | 5,130 | — | Match — WF offers ≦±25 |
| ≦±50 ppm/°C TCR | 5,130 | — | Match — WF offers ≦±50 |
The MF series does not reach ±0.01%, ≦±3 or ≦±5 ppm/°C. Those grades exist only in the WF
series. Conversely the WF series does not offer ±0.05% or ±0.25% at any size. The two thin
film series are not a ladder; they are two different grids.
The crossing is exact. 1,026 resistance values times five tolerances times four TCR grades is
20,520 — precisely the row count in the extract. No holes, no extras.
How many resistance values are in the MF series?
1,026, spanning 10 Ω to 1 MΩ. The series carries 205 values in each of the five decades, plus
the single endpoint at 1 MΩ. The sequence starts 10.0, 10.1, 10.2, 10.4, 10.5, 10.6, 10.7,
10.9, 11.0 and continues on the same spacing.
205 values per decade is not a standard preferred-number series. E96 gives 96 and E192 gives
192. The MF grid is denser than E192 by thirteen values per decade.
Flagged for review. Walsin’s export does not name the preferred-number series it used.
205 values per decade matches neither E96 nor E192. Ask Walsin which series the MF
resistance table follows before telling a customer their E192 value is available — most
are, but the claim needs confirming value by value.
The top of the range matters. The last values before the endpoint are 953 kΩ, 965 kΩ, 976 kΩ,
988 kΩ and 1 MΩ. Above 1 MΩ the series stops; a tantalum nitride part at 2 MΩ does not exist
in this catalogue.
How does the MF series compare with Walsin’s WF precision thin film?
At the same footprint and the same resistance, the MF part gives more power and a coarser
best-case tolerance. The WF part gives ±0.01% and 3 ppm/°C. The MF part gives ±0.05% and
10 ppm/°C at best, with a 60% higher power rating.
| Field | MF12F4700ATL (tantalum nitride) | WF12B4700TTL (WF thin film) | WF12J4700BTL (thick film TC25) | Match / mismatch |
|---|---|---|---|---|
| Film | Tantalum nitride | Thin film | Thick film | Mismatch — three films |
| Case size | 1206 (3216) | 1206 (3216) | 1206 (3216) | Match — all three |
| Resistance | 470 Ω | 470 Ω | 470 Ω | Match — all three |
| Tolerance | ±0.05% | ±0.01% | ±0.1% | Mismatch — MF sits between |
| TCR | ≦±15 ppm/°C | ≦±3 ppm/°C | ≦±25 ppm/°C | Mismatch — MF sits between |
| Rated power | 2/5 W | 1/4 W | 1/4 W | Mismatch — MF is 60% higher |
| Packaging | 7″ reel taping | 7″ reel taping | 7″ reel taping | Match — all three |
| Termination | Sn base (lead free) | Sn base (lead free) | Sn base (lead free) | Match — all three |
| Best tolerance in series | ±0.05% | ±0.01% | ±0.1% | Mismatch — 10:1 across the three |
| Case sizes in series | 1 | 8 | 8 | Mismatch — MF is single footprint |
Read the power row carefully. 2/5 W against 1/4 W at the same 1206 footprint is a 60%
increase in dissipation allowance from the same body size. For a part sitting in a sensing
leg, that row often decides the choice before tolerance does.
The MF series is also the only place in Walsin’s thin film catalogue where ±0.05% and ±0.25%
appear. If a BOM calls for ±0.05% at 1206, MF is the Walsin answer and there is no WF
fallback.
Why choose tantalum nitride over a standard thin film resistor?
For environmental stability rather than initial accuracy. The MF series does not beat the WF
series on tolerance or TCR. It beats it on power density at 1206, offers two tolerance grades
WF does not, and uses the film specified where a part must survive humidity for years.
Three selection cases come out of the data. ±0.05% or ±0.25% at 1206 — MF only. More than
1/4 W at 1206 in a precision film — MF only. ±0.01%, or TCR tighter than 10 ppm/°C — WF only.
Flagged for review. Walsin’s export carries no humidity, load-life or 85/85 data for
any thin film series. Any environmental comparison between MF and WF must come from the
datasheets, which Venatech should obtain and attach before this post is used in a
qualification discussion.
How do I read a Walsin MF part number?
Four fields in twelve characters. MF is the series prefix. The next two digits are the
case size, always 12. The fifth character is the TCR grade. The next four characters are
the resistance value. The tenth character is the tolerance grade. TL closes it.
| Character | Position | Value in MF12F4700ATL |
Means |
|---|---|---|---|
| MF | 1–2 | MF | Series prefix — see the caution below |
| 12 | 3–4 | 12 | 1206 (3216), the only size in the series |
| F | 5 | F | TCR ≦±15 ppm/°C |
| 4700 | 6–9 | 4700 | 470 Ω |
| A | 10 | A | Tolerance ±0.05% |
| TL | 11–12 | TL | Taping and lead-free termination tail |
The TCR codes verified across the MF extract are W for ≦±10, F for ≦±15, R for ≦±25 and Q for
≦±50 ppm/°C. The tolerance codes are A for ±0.05%, B for ±0.1%, C for ±0.25%, D for ±0.5% and
F for ±1%. F appears in both positions with different meanings: MF12F4700FTL is a
≦±15 ppm/°C part at ±1%.
Does a part number starting MF always mean tantalum nitride?
No. 14,791 part numbers in Walsin’s thick film chip resistor export also begin MF, and all
of them are automotive series. Added to the 20,520 tantalum nitride parts, 35,311 Walsin
resistors share the MF prefix across two technologies and two separate catalogues.
Unique to Venatech’s data. The
MFprefix is not a tantalum nitride marker. Venatech’s
extract holds 20,520 thin film MF parts and 14,791 thick film parts whose numbers also
beginMF: 5,810 in Triple Power Surge Chip Resistor (Automotive), 4,986 in High Power
Chip Resistor (Automotive) and 3,995 in High Precision Thick Film TC100 (Automotive).
There are zero exact part-number collisions. The fifth character separates them — tantalum
nitride uses Q, R, F or W, the thick film automotive parts use E, P or H. Every
MF-prefixed thick film series carries “(Automotive)” in its name; none of the tantalum
nitride parts do.
MF12F4700ATL is a tantalum nitride part at ±0.05% and 15 ppm/°C. MF12H4700DTL is a thick
film automotive part at ±0.5% and 100 ppm/°C. Same prefix, same case size, same resistance,
different catalogue. A BOM line reading “MF12, 470R” has not specified a part.
Two of Walsin’s three MF export files return zero rows in Venatech’s extract, so all 20,520
parts come from one file. A search that returns nothing for MF is not evidence the parts do
not exist.
FAQ
What is the Walsin MF series?
Walsin’s tantalum nitride thin film chip resistor series. Venatech holds 20,520 MF parts,
all 1206 (3216) and all rated 2/5 W. The series offers five tolerance grades from ±0.05% to
±1% and four TCR grades from ≦±10 to ≦±50 ppm/°C, over 1,026 resistance values from 10 Ω to
1 MΩ.
What case size is the Walsin tantalum nitride resistor?
1206 (3216), and only 1206. All 20,520 MF parts in Venatech’s extract sit in that single
footprint. There is no tantalum nitride option at 0402, 0603, 0805, 1210, 2010 or 2512 in
this catalogue. A design that needs the film has to accommodate the 1206 land pattern.
What is the tightest tolerance in the MF series?
±0.05%, on 4,104 parts. The MF series does not offer ±0.01%; that grade exists only in
Walsin’s WF precision thin film series, which reaches it from 0402 upward. The tightest MF
TCR grade is ≦±10 ppm/°C, against ≦±3 ppm/°C in the WF series.
Why is the MF series rated 2/5 W and not 1/4 W?
2/5 W is the only rating Walsin publishes for the series. At 1206 it is 60% more dissipation
allowance than the 1/4 W of the WF thin film and high precision thick film parts at the same
footprint. A BOM filter written to accept only 1/4 W or 1/2 W at 1206 will exclude the whole
MF series.
Can I use a tantalum nitride resistor above 1 MΩ?
Not in this series. The MF resistance table runs from 10 Ω to 1 MΩ over 1,026 values, and 1
MΩ is the endpoint. Above it the tantalum nitride option stops. Walsin’s WF precision thin
film series continues to 3 MΩ, and separate high ohm thick film series go further.
How do I tell a tantalum nitride MF part from a thick film MF part?
By the fifth character. 35,311 Walsin resistors begin MF across both technologies.
Tantalum nitride uses Q, R, F or W in position five; the thick film automotive parts use E,
P or H. There are no exact part-number collisions between the two sets, and every
MF-prefixed thick film series is an automotive series.
Is the MF resistance table an E192 series?
It carries 205 values per decade, which is denser than E192 at 192 and much denser than E96
at 96. Walsin’s export does not name the preferred-number series it followed, so a specific
E192 value should be checked against the table rather than assumed present.
Is the MF series available on tape and reel?
Every one of the 20,520 MF parts in Venatech’s extract lists 7″ reel taping and a lead-free
tin base termination. No alternative packaging appears on any row. Stock position is a
snapshot and moves, so confirm availability against the specific part number.
Next step
Tantalum nitride is a narrow, deep series: one footprint, one power rating, a complete grid
of everything else. Easy to source once you know it exists, easy to miss if your filter
starts from case size or power.
Send your BOM and Venatech Limited, an authorised Walsin distributor in Hong Kong, will tell
you which lines the MF series can carry at 1206, which need the WF series, and every field
where the closest Walsin part differs from the one you specified.
Send your BOM to Venatech · Browse the
Walsin thin film range · Read
Thin film vs thick film chip resistors and
The CT suffix: orderable Walsin part numbers.