Walsin Technology (Walsin) builds anti-sulfuration resistors twice over: 15,080 SF thin
film parts in the thin film catalogue and 2,772 SA thick film array parts in the chip
resistor catalogue. Counting every anti-sulfuration series Venatech holds brings the total to
56,227 parts across nine series, two catalogues and five different part-number prefixes.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin’s parametric
exports for both catalogues — 93,914 thin film rows and 234,815 chip resistor rows. Every
count below is measured from those extracts.
Flagged for review. We hold no public datasheet URL for the Anti-Sulfuration Thin Film
Chip Resistor / SF Series or for the Anti-Sulfuration Thick Film Chip Resistor Array
series. Both are cited by series name here. Confirm the public PDF addresses with Walsin
before publishing.
What is an anti-sulfuration resistor?
A chip resistor built so that sulfur in the surrounding air cannot reach and consume the
silver in its internal electrode. In a standard thick film chip resistor the inner electrode
is silver-bearing. Atmospheric sulfur migrates through the protective coat, forms silver
sulfide, and the resistor drifts high and then opens.
The failure is slow, environmental and invisible on an incoming inspection. It shows up in
the field, months into service, in units sited near rubber seals, vulcanised cable, road
traffic, hot springs, paper mills, sewage plants and oil-bearing machinery. The board is fine
when it ships.
Flagged for review. The silver sulfide mechanism above is the generally understood
failure path, not a quoted Walsin statement. Venatech does not hold Walsin’s construction
drawing or its sulfur test conditions for either series. Obtain the datasheets before
quoting a test method or a duration in a qualification document.
Which Walsin series are anti-sulfuration?
Nine, in two catalogues. One is thin film: the SF series, 15,080 parts. Eight are thick film,
totalling 41,147 parts, and they are scattered across four different series groups in the
chip resistor export. No single Walsin filter returns all nine.
| Series | Catalogue | Parts held | Part-number prefix | Case sizes |
|---|---|---|---|---|
| Anti-Sulfuration Thin Film Chip Resistor / SF | Thin film | 15,080 | SF | 1206, 2010 |
| Thick Film High Grade Anti-Sulfuration (Automotive) | Chip resistor | 12,871 | SR | 0402 to 2512 |
| Thick Film General Purpose Anti-Sulfuration (Automotive) | Chip resistor | 10,659 | WR | 0201 to 1210 |
| Thick Film High Power Chip Resistor (Anti-Sulfuration) | Chip resistor | 9,135 | SF and WF | 0402 to 2512 |
| High Precision Anti-Sulfuration Chip Resistor | Chip resistor | 5,710 | SF | 0402 to 1210 |
| Anti-Sulfuration Array 0402×4, Convex | Chip resistor | 693 | SA | 0402 |
| Anti-Sulfuration Array 0402×2, Convex | Chip resistor | 693 | SA | 0402 |
| Anti-Sulfuration Array 0603×4, Convex | Chip resistor | 693 | SA | 0603 |
| Anti-Sulfuration Array 0603×2, Convex | Chip resistor | 693 | SA | 0603 |
Unique to Venatech’s data. Anti-sulfuration is not one Walsin series. Venatech’s
extracts hold 56,227 anti-sulfuration resistors — 15,080 thin film and 41,147 thick film —
across nine series, four chip resistor series groups and five distinct part-number prefixes:
SF, SR, WR, WF and SA. One series, High Power Chip Resistor (Anti-Sulfuration), splits
across two prefixes on its own: 4,980 parts begin SF and 4,155 begin WF. A search on any one
prefix finds a fraction of the range. This mapping is not published anywhere.
The practical reading: if a specification says “anti-sulfuration”, the next question is which
of nine series, because the tolerance, TCR, power and case size coverage differ on every one.
What does the SF thin film anti-sulfuration series cover?
Two case sizes, heavily weighted to one. 14,810 of the 15,080 SF thin film parts are 2010
(5025); the remaining 270 are 1206 (3216). Tolerance runs from ±0.05% to ±1%. TCR is ≦±25 on
9,418 parts, ≦±50 on 5,658 and ≦±10 on 4.
| Field | SF at 2010 (5025) | SF at 1206 (3216) | Match / mismatch |
|---|---|---|---|
| Parts held | 14,810 | 270 | Mismatch — 98.2% sit at 2010 |
| Resistance span | 4.7 Ω – 3 MΩ | 1.00 Ω – 50.5 Ω | Mismatch — no overlap above 50.5 Ω |
| Resistance values | 1,105 | 29 | Mismatch — 38:1 |
| Rated power | 1/2 W and 3/4 W | 1/8 W and 1/4 W | Mismatch — 2010 is 4× higher |
| Tolerance range | ±0.05% to ±1% | ±0.05% to ±1% | Match — same five grades |
| TCR grades | ≦±25 and ≦±50 | ≦±10, ≦±25 and ≦±50 | Mismatch — ≦±10 only at 1206 |
| Packaging | 7″ reel taping | 7″ reel taping | Match |
| Termination | Sn base (lead free) | Sn base (lead free) | Match |
The two sizes are doing different jobs. The 1206 parts stop at 50.5 Ω and start at 1.00 Ω —
that is a low-ohm sensing range, not a general-purpose range. The 2010 parts run the full
4.7 Ω to 3 MΩ span at 1/2 W and 3/4 W. SF12T1R00ATL is the 1 Ω 1206 part at ±0.05% and
≦±50 ppm/°C, 1/8 W. SF20U2944FTL is a 2.94 MΩ 2010 part at ±1% and ≦±25 ppm/°C, 1/2 W.
Note the ≦±10 ppm/°C grade: four parts, all at 1206, all ±1%. It is the tightest TCR in the
anti-sulfuration range and it exists on four part numbers.
What does the SA thick film array series cover?
Four series of exactly 693 parts each — 0402×4, 0402×2, 0603×4 and 0603×2, all convex type,
2,772 parts in total. Tolerance is ±1% on 2,284 parts, ±5% on 484 and Jumper on 4. Resistance
runs from 0 Ω to 1 MΩ over 596 entries in each series.
The element count is in the fifth character of the part number, not in the size field. X is
a four-element array; Y is a two-element array. SA04X4700FTL and SA04Y10R0FTL are both
0402 (1005) in the Size column, and only that character tells you whether you are buying four
resistors in a package or two.
| Series | Parts | Size in export | Fifth character | Rated power | TCR |
|---|---|---|---|---|---|
| 0402×4, Convex | 693 | 0402 (1005) | X | 1/16 W (Jumper 1/10 W) | ≦±300 ppm/°C |
| 0402×2, Convex | 693 | 0402 (1005) | Y | 1/16 W (Jumper 1/10 W) | ≦±300 ppm/°C |
| 0603×4, Convex | 693 | 0603 (1608) | X | 1/10 W | ≦±200 ppm/°C |
| 0603×2, Convex | 693 | 0603 (1608) | Y | 1/10 W | ≦±200 ppm/°C |
Each of the four series carries a 693-row table with 596 distinct resistance entries, so the
four series are one value list replicated across two sizes and two element counts. Each series
holds exactly one Jumper part.
How does an anti-sulfuration array compare with a standard array at the same size?
Same footprint, same resistance, same power, looser TCR. At 0603×4 and 470 Ω the
anti-sulfuration part is specified at ≦±200 ppm/°C where the standard convex array is
≦±100 ppm/°C. The sulfur resistance is bought with a factor of two on temperature
coefficient.
| Field | SA06X4700FTL (anti-sulfuration) | WA06X4700FTL (standard convex) | SA04X4700FTL (anti-sulf. 0402) | Match / mismatch |
|---|---|---|---|---|
| Series group | Array (Anti-Sulfuration) | Thick Film Chip Resistor Array | Array (Anti-Sulfuration) | Mismatch — two groups |
| Elements | 4 | 4 | 4 | Match — all three |
| Case size | 0603 (1608) | 0603 (1608) | 0402 (1005) | Mismatch — third part smaller |
| Resistance | 470 Ω | 470 Ω | 470 Ω | Match — all three |
| Tolerance | ±1% | ±1% | ±1% | Match — all three |
| TCR | ≦±200 ppm/°C | ≦±100 ppm/°C | ≦±300 ppm/°C | Mismatch — anti-sulf. is looser |
| Rated power | 1/10 W | 1/10 W | 1/16 W | Mismatch — 0402 is lower |
| 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 |
| Sulfur resistance | Yes, per series name | Not claimed | Yes, per series name | Mismatch — the whole point |
The TCR row is the one to carry into a design review. Swapping a standard 0603 array for the
anti-sulfuration part at the same value and the same tolerance doubles the published
temperature coefficient limit. In a divider or a pull-up network that is usually irrelevant.
In anything that has to hold a ratio over temperature it is not.
Does anti-sulfuration cost you anything in tolerance or TCR?
In the arrays, yes — TCR doubles from ≦±100 to ≦±200 at 0603 and from ≦±200 to ≦±300 at 0402.
In the thin film SF series, no: it reaches ±0.05% and ≦±25 ppm/°C, the same grades as
Walsin’s non-sulfur thin film parts at the same sizes. The penalty is a thick film array
penalty, not a general one.
The high precision thick film route sits between them. SF12H4700BTL is a 1206 High Precision
Anti-Sulfuration part at ±0.1% and ≦±100 ppm/°C, 1/4 W. That series holds 5,710 parts at
±0.1% and ±0.5% only, with TCR at ≦±100 on 5,700 of them. It gets you ±0.1% with sulfur
resistance, which no array does, but it does not reach ≦±50 ppm/°C.
| Route | Best tolerance | Best TCR | Case sizes | Parts held |
|---|---|---|---|---|
| SF thin film | ±0.05% | ≦±10 ppm/°C (4 parts) | 1206, 2010 | 15,080 |
| High Precision Anti-Sulfuration | ±0.1% | ≦±100 ppm/°C | 0402 to 1210 | 5,710 |
| High Grade Anti-Sulfuration (Auto) | ±1% | ≦±100 ppm/°C | 0402 to 2512 | 12,871 |
| General Purpose Anti-Sulfuration (Auto) | ±1% | not published as a single grade | 0201 to 1210 | 10,659 |
| SA arrays | ±1% | ≦±200 ppm/°C | 0402, 0603 | 2,772 |
Pick the row that matches the specification, then check the case size column before the
tolerance column. Three of the five routes do not exist at 0201 or above 1210.
How do I find every Walsin anti-sulfuration part?
Not with a part-number search. Five prefixes carry anti-sulfuration parts — SF, SR, WR, WF and
SA — and two of them, WF and WR, are also used by tens of thousands of parts that make no
sulfur claim at all. The only reliable filter is the Series field, and it needs a substring
match on “Anti-Sulfuration”.
Three traps sit in that substring. The series names spell it “Anti-Sulfuration” with an
initial capital and a hyphen, so a case-sensitive search for “sulfur” or “anti sulphuration”
returns nothing. The word appears inside a parenthesis on two series — “Thick Film High Power
Chip Resistor (Anti-Sulfuration)” and the series group “Thick Film Chip Resistor Array
(Anti-Sulfuration)”. And two of the nine series sit in the thin film export, which is a
separate download from the chip resistor export.
Flagged for review. Walsin’s public parametric search may expose these nine series
differently from the exports Venatech holds. We have not re-tested the live search tool
against this list. Confirm the public search paths before publishing a “how to find it”
instruction.
Do the SA array part numbers paste into a BOM?
Not all of them. 488 of the 2,772 anti-sulfuration array part numbers contain an embedded
space, and across the whole anti-sulfuration range 6,213 of the 41,147 thick film part numbers
do. SA06X471 JTL is a real Walsin part number with a space between 471 and JTL.
The pattern is consistent: parts whose resistance is expressed as three digits plus a
multiplier — the ±5% and Jumper rows — carry a space where a ±1% part carries a fourth digit.
SA06X4700FTL has no space. SA06X471 JTL does, at the same 470 Ω.
That space breaks a paste into a search box, a BOM importer or a distributor API. It also
breaks a string comparison against a customer’s own BOM, which is how a line that looked
crossed turns out not to be. Strip it, keep it, or quote it — but decide which, and apply the
same rule on both sides of the comparison.
FAQ
What does anti-sulfuration mean on a chip resistor?
That the resistor is built so atmospheric sulfur cannot reach and consume the silver in its
internal electrode. A standard thick film chip resistor uses a silver-bearing inner electrode;
sulfur forms silver sulfide and the part drifts high and then opens. The failure appears in
service, not at incoming inspection.
How many anti-sulfuration resistors does Walsin make?
Venatech’s extracts hold 56,227: 15,080 thin film SF parts and 41,147 thick film parts across
eight further series. They sit in two separate catalogues, four chip resistor series groups,
and five different part-number prefixes — SF, SR, WR, WF and SA. No single Walsin filter
returns all nine series.
What is the difference between the SF and SA series?
SF is a thin film single-element resistor at 1206 and 2010, reaching ±0.05% tolerance. SA is a
thick film resistor array at 0402 and 0603, in two-element and four-element versions, reaching
±1%. Different catalogues, different technologies, different footprints. Both carry
anti-sulfuration in the series name.
Does an anti-sulfuration array have worse TCR than a standard array?
In this catalogue, yes. At 0603 the anti-sulfuration array is specified at ≦±200 ppm/°C where
the standard convex array is ≦±100 ppm/°C, at the same 470 Ω and the same ±1%. At 0402 the
anti-sulfuration part is ≦±300 against ≦±200. Check the ratio stability the circuit needs
before swapping.
Can I get a precision anti-sulfuration resistor?
Yes, by two routes. The SF thin film series reaches ±0.05% tolerance at 1206 and 2010. The High
Precision Anti-Sulfuration thick film series holds 5,710 parts at ±0.1% and ±0.5% across 0402
to 1210, with TCR at ≦±100 ppm/°C. The arrays do not go below ±1%.
Where do sulfur failures actually happen?
In service environments with atmospheric sulfur: near rubber seals and vulcanised cable, in
road traffic, hot springs, paper mills, sewage treatment, oil-bearing machinery and heavy
industry. The board passes every test at manufacture. The failure develops over months, which
is why the part choice has to be made at design time.
Why do some Walsin anti-sulfuration part numbers contain a space?
Because the resistance field is shorter on ±5% and Jumper parts, and Walsin’s export leaves the
gap in. 488 of the 2,772 array parts and 6,213 of the 41,147 thick film anti-sulfuration parts
carry an embedded space. SA06X471 JTL is real. It will not paste cleanly into a BOM importer
or a search box.
How do I tell a two-element array from a four-element array?
By the fifth character, not the Size column. X is four elements, Y is two. SA04X4700FTL
and SA04Y10R0FTL both show 0402 (1005) in the Size field. Walsin’s export puts the element
count only in the Series name and in that single character of the part number.
Next step
Anti-sulfuration is nine series, not one, and the right answer depends on whether the line
needs precision, power, an array or a low-ohm sense value. Each route has a different case size
window.
Send your BOM and Venatech Limited, an authorised Walsin distributor in Hong Kong, will return
which of the nine series can carry each line, the tolerance and TCR available there, and every
field where the closest Walsin part differs from what you specified.
Send your BOM to Venatech · Browse the
Walsin chip resistor range · Read
Chip resistor arrays explained and
Thin film vs thick film chip resistors.