High Precision Thick Film vs Thin Film Precision: Two Walsin Series That Overlap

They do not compete on precision. They divide at tolerance. Walsin Technology (Walsin)
lists 52,027 parts in its high precision thick film chip resistor group and 58,314 in its
thin film precision WF series. The thick film group spans ±0.1% to ±1%. The thin film series
puts 52,808 of its 58,314 parts at a single tolerance, ±0.01%, and almost nothing between.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 137 of Walsin’s
chip resistor export files and all 20 thin film files — 234,815 and 93,914 rows. Every part
number and every count below comes from that extract. Counts are of part numbers, not pieces.

What is the difference between high precision thick film and thin film precision?

The resistive element. Thick film is a screen-printed and fired paste, laser-trimmed to
value. Thin film is a sputtered metal alloy layer, typically nichrome, trimmed the same way.
Thin film holds a tighter temperature coefficient and better long-term stability. Thick film
holds a wider resistance range and a wider power range in the same case size.

Walsin builds both. The naming is where engineers lose an afternoon, because the two groups
share part-number prefixes and overlap on three of their four tolerances.

Which Walsin series gives you ±0.1%, and how many parts are there?

The thick film group, by a factor of nearly ten. Walsin’s high precision thick film group
holds 16,103 parts at ±0.1%. The thin film precision WF series holds 1,674. If ±0.1% is the
tolerance your circuit needs, the deeper catalogue is the thick film one, not the thin film
one.

Here is the full tolerance split across both groups:

Tolerance	High precision thick film (52,027)	Thin film precision WF (58,314)	Match / mismatch
±0.01%	—	52,808	Mismatch — thin film only
±0.1%	16,103	1,674	Match on tolerance; 9.6× more thick film parts
±0.25%	5,369	—	Mismatch — thick film only
±0.5%	23,041	1,916	Match on tolerance; 12.0× more thick film parts
±1%	7,514	1,916	Match on tolerance; 3.9× more thick film parts

Source: Walsin’s chip resistor and thin film parametric exports held by Venatech, counted
23 September 2026.

The shape of that table is the point. Thin film is bimodal — ultra-precision at ±0.01%, or a
thin commodity band at ±0.5% and ±1%. The middle of the precision market, ±0.1% to ±0.25%,
is served by thick film.

Take one real design point: 0603 case, 10 kΩ. The two groups answer it completely differently.

Part number	Group	Tolerance	TCR (ppm/°C)	Rated power	Match / mismatch
WF06J1002BTL	Thick film, TC25	±0.1%	≦±25	1/10 W	Tightest TCR in thick film at this point
WF06K1002BTL	Thick film, TC50	±0.1%	≦±50	1/10 W	Mismatch on TCR vs the TC25 part
WF06H1002BTL	Thick film, TC100	±0.1%	≦±100	1/10 W	Mismatch on TCR
SF06H1002BTL	Thick film, anti-sulfuration	±0.1%	≦±100	1/10 W	Adds sulfur resistance; TCR unchanged
WF06B1002TTL	Thin film WF	±0.01%	≦±3	1/10 W	Mismatch on tolerance — 10× tighter than any thick film part here
WF06Z1002TTL	Thin film WF	±0.01%	≦±5	1/10 W	Mismatch on tolerance
WF06R1002TTL	Thin film WF	±0.01%	≦±25	1/10 W	Matches WF06J1002BTL on TCR, not on tolerance

At 0603 and 10 kΩ, Walsin lists 20 high precision thick film part numbers across four
tolerances, and 8 thin film precision part numbers at one tolerance. Counted across our
extract, every one of those 8 is ±0.01%. There is no ±0.1% thin film part at 0603 10 kΩ in
the data we hold.

How do you tell a Walsin thick film part from a thin film part?

By the fifth character, and by nothing else in the prefix. All three prefixes used by Walsin’s
thin film lines — WF, MF and SF — are also used by thick film parts.

Prefix	Thick film rows	Thin film rows	Match / mismatch
WF	76,968	58,314	Mismatch of meaning — same prefix, both technologies
MF	14,791	20,520	Mismatch of meaning — thick film in four series groups, thin film tantalum nitride
SF	10,690	15,080	Mismatch of meaning — thick film high precision and high power, thin film anti-sulfuration

No part number appears in both the thick film and thin film extracts. We checked all 328,729
rows: the exact-string overlap is zero. So the prefix is not ambiguous as a whole part number.
It is simply useless as a technology filter, and a prefix filter is what most people try first.

The character that does separate them is the TCR code in position five:

Position-5 code	Technology	TCR published
H	Thick film	≦±100, ≦±200, or −200 to +400
J	Thick film	≦±25
K	Thick film	≦±50 or ≦±100
B	Thin film	≦±3
Z	Thin film	≦±5
W	Thin film	≦±10
F	Thin film	≦±15
R, U	Thin film	≦±25 or ≦±50
Q, T	Thin film	≦±25 or ≦±50

The two sets do not intersect. Across 110,341 parts in these two groups, no position-5 letter
is used by both technologies. That makes it a one-character test you can check yourself against
the table above, and we have not seen it published anywhere.

The tolerance letter in position ten is a second, partial test. T means ±0.01% and appears
only on thin film. C means ±0.25% and appears only on thick film. B, D and F — ±0.1%,
±0.5% and ±1% — appear on both.

Does a series called TC100 always give you 100 ppm/°C?

No. 4,523 of the 52,027 high precision thick film parts publish a TCR looser than the number
printed in their own series name. The series name is a group label, not a specification.

Series	Parts	TCR in the name	Parts looser than the name	What they actually publish
TC25	3,087	25	0	All ≦±25. Match
TC50	14,797	50	1,094	13,703 at ≦±50; 1,094 at ≦±100. Mismatch
TC50 (Automotive)	8,680	50	0	All ≦±50. Match
TC100	11,190	100	2,284	8,906 at ≦±100; 2,284 at ≦±200. Mismatch
TC100 (Automotive)	3,995	100	1,145	2,850 at ≦±100; 570 at ≦±200; 575 at −200 to +400. Mismatch
TC100 LF100ppm	4,568	100	0	All ≦±100. Match

The reason is physical, and Walsin’s own datasheet states it. Thick film TCR degrades at both
ends of the resistance range. The MR general purpose datasheet tabulates ±200 ppm/°C above
1 MΩ and −200 to +400 ppm/°C at 10 Ω and below. Every one of the 585 high precision parts
carrying −200 to +400 is 10 Ω or lower — we checked all 585, and the maximum resistance among
them is exactly 10.0 Ω. The series name does not change the paste.

Walsin’s thin film WF series behaves differently, because its TCR is set per part by the
position-5 code rather than by a group label. Its best grade is ≦±3 ppm/°C on 3,064 parts.
No high precision thick film part in the catalogue goes tighter than ≦±25.

Which series goes higher in resistance?

Thick film, by more than a factor of three. The high precision thick film group runs 1.00 Ω to
10 MΩ. The thin film precision WF series runs 1.00 Ω to 3 MΩ. Above 3 MΩ the thin film option
disappears and thick film is the only precision answer Walsin publishes.

Attribute	High precision thick film	Thin film precision WF	Match / mismatch
Resistance range	1.00 Ω – 10 MΩ	1.00 Ω – 3 MΩ	Mismatch above 3 MΩ
Parts at or above 1 MΩ	1,565	872	Both populated
Tightest tolerance	±0.1%	±0.01%	Mismatch — thin film 10× tighter
Tightest TCR	≦±25	≦±3	Mismatch — thin film 8× tighter
Case sizes	0201 – 2512, 8 sizes	0201 – 2512, 8 sizes	Match
Termination	Sn base, lead free	Sn base, lead free	Match
Automotive sub-series	12,675 parts across two series	None in this series	Mismatch

Distinct resistance values tell the same story from the other side: 802 in the thick film
group against 1,181 in thin film. Thin film is denser inside a narrower span. Thick film is
sparser across a wider one.

Which one should you specify?

Work from the binding constraint, not from the word precision.

• You need ±0.01% or a TCR below 25 ppm/°C. Thin film WF. Nothing else in either group
  reaches it.
• You need ±0.1% or ±0.25% with real part choice. High precision thick film. The ±0.1%
  shelf is 16,103 parts deep against 1,674 in thin film, and ±0.25% exists only in thick film.
• You need above 3 MΩ at a precision tolerance. High precision thick film.
• You need 10 Ω or below with a predictable TCR. Neither group will give you a tight
  thick film TCR there. Read the −200 to +400 band and consider a metal or thin film current
  sense part instead.
• Your board sees sulfur. The high precision anti-sulfuration series, 5,710 parts, keeps
  ±0.1% to ±0.5% and carries the SF prefix. Note that SF is also a thin film prefix.
• It is an automotive programme. The thick film group carries 12,675 parts in two
  automotive series. The thin film precision WF series carries none; Walsin’s thin film
  automotive line is the separate WF-Q professional series, and all nine of its exports
  return zero rows.

For how the two technologies differ in construction and behaviour rather than in catalogue
depth, see Thin film vs thick film chip resistors.
For why a part number that looks right may still not order, see
Why Walsin part numbers do not paste into your BOM.
The full range is on the Walsin chip resistor range page.

The short version

Thin film owns ±0.01% and single-digit TCR. Thick film owns ±0.1% and ±0.25% by depth of
catalogue, and owns everything above 3 MΩ. The prefix will not tell you which you are holding —
read the fifth character. And never take the TCR from the series name: 4,523 parts in the high
precision group publish a looser figure than their own label.

Send us the tolerance, TCR and resistance your circuit actually needs and we will tell you
which of the two groups has parts at that point, with the part numbers. Or give us one part
number and ask us to cross it.

Check it against the catalogue yourself. Cross-reference accepts one part number or a whole BOM column and prints the mismatches as plainly as the matches — qualification stays with you, which is the honest division of labour. Ready stock covers the chip resistor lines held in Hong Kong.

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Frequently asked questions