Chip Resistors Above 10 Megohm: A Selection Checklist

Walsin Technology (Walsin) lists 488 thick film chip resistors in its High Ohm series
group, spanning 1.1 megohms to 100 megohms at 0603, 0805 and 1206, plus eleven parts at
0402. The general purpose thick film range stops at exactly 10 megohms, so anything above
that sits in a series group most parametric searches never reach.

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What is the highest resistance Walsin lists in a thick film chip resistor?

100 megohms. Venatech Limited, an authorised Walsin distributor in Hong Kong, holds six
100 MΩ parts in the High Ohm series group — WF06G1006FTL, WF06G107 JTL,
WF08G1006FTL, WF08G107 JTL, WF12G1006FTL and WF12G107 JTL — one ±1% and one ±5%
part at each of 0603, 0805 and 1206.

Above 100 MΩ there is nothing, in any series group, at any case size. The type code that
identifies the series is G in position five: WF12G1006FTL reads as 1206, high ohm,
1006 for 100 followed by six zeros — 100 MΩ — then F for ±1%.

Part number	Size	Resistance	Tolerance	TCR	Rated power	Space in part number
WF12G1006FTL	1206 (3216)	100 MΩ	±1%	≦±200	1/4 W	No
WF12G107 JTL	1206 (3216)	100 MΩ	±5%	≦±200	1/4 W	Yes, before JTL
WF08G1006FTL	0805 (2012)	100 MΩ	±1%	≦±200	1/8 W	No
WF06G1006FTL	0603 (1608)	100 MΩ	±1%	≦±200	1/10 W	No
WF12G1105FTL	1206 (3216)	11 MΩ	±1%	≦±200	1/4 W	No
WF04G306 JTL	0402 (1005)	30 MΩ	±5%	≦±200	1/16 W	Yes, before JTL

Why does the general purpose thick film range stop at exactly 10 megohms?

Because Walsin draws the line there and puts everything above it in a different series
group. Counting the 75,628 parts in the Thick Film General Purpose group, the maximum
resistance is exactly 10,000,000 Ω and the number of parts above it is zero. Not few —
zero.

Walsin’s own general purpose approval sheet confirms the boundary: the resistance range for
the WR12, WR08, WR06 and WR04 series is given as 1 Ω to 10 MΩ at both ±1% and ±5%,
and the sheet splits the TCR band at 10 MΩ within the same table.

So a search that works upwards from the general purpose series hits a hard wall at
WR12W1005FTL, a 1206 ±1% 10 MΩ part.

Unique to Venatech’s data. Walsin’s general purpose thick film range tops out at
exactly 10 MΩ — 75,628 parts, zero of them above 10,000,000 Ω. The 488 parts in the High
Ohm series group are reached by a different search path entirely, and 416 of them are
above 10 MΩ. Across the whole 234,815-part chip resistor extract, 1,348 parts exceed
10 MΩ and they are spread over four different series groups. Measured from Walsin’s own
export; not published anywhere.

Does the High Ohm series group only contain parts above 10 megohms?

No. Walsin names the group Thick Film High Ohm Chip-Resistor (>10MΩ), but 72 of its 488
parts are at or below 10 MΩ. The group actually starts at 1.1 MΩ, which overlaps the
general purpose range by nearly an order of magnitude.

The overlap is structured, not accidental. At 0603, 0805 and 1206 the list runs through 24
values from 1.1 MΩ to 10 MΩ before continuing above it — 24 values at three sizes is exactly
the 72 parts.

Claim	What the data shows	Match / mismatch
Series group name says >10MΩ	72 of 488 parts are at or below 10 MΩ	Mismatch — the group starts at 1.1 MΩ
Series group is the only home for parts above 10 MΩ	416 of the 1,348 parts above 10 MΩ are in it	Mismatch — 932 sit in three other groups
Group covers four case sizes	0603, 0805, 1206 at 159 parts each; 0402 at 11	Match, but 0402 coverage is minimal
Group offers ±1% and ±5%	333 at ±1%, 155 at ±5%	Match
Group offers a choice of TCR	All 488 are ≦±200 ppm/°C	Mismatch — one band only

Filter on the series group name and 72 of your hits are not above 10 MΩ. Filter on
resistance instead and you get 1,348 hits across four groups, not 416.

Is a high ohm chip resistor limited by power or by voltage?

Voltage, and not by a small margin. A 1206 rated 1/4 W at 100 MΩ would need 5,000 V across
it to reach rated dissipation. The maximum continuous working voltage for a 1206 in
Walsin’s general purpose sheet is 200 V. At 200 V a 100 MΩ part dissipates 0.4 mW — about
0.16% of its 1/4 W rating.

The crossover is calculable. Rated continuous working voltage is the lower of the square
root of rated power times resistance, and the size’s maximum operating voltage:

Size	Rated power in the High Ohm group	Max operating voltage, WR series	Resistance above which voltage governs	Dissipation at that voltage on a 100 MΩ part
1206 (3216)	1/4 W	200 V	40 kΩ	0.40 mW
0805 (2012)	1/8 W	150 V	180 kΩ	0.23 mW
0603 (1608)	1/10 W	75 V	56.3 kΩ	0.06 mW
0402 (1005)	1/16 W	50 V	40 kΩ	0.03 mW

Every part in this group is well past its crossover, so the rated power column is close to
decorative. What matters instead is worst-case voltage and the surface leakage path. At 100 MΩ the
element is comparable in resistance to a contaminated board surface, so coating, flux residue
and humidity become part of the divider you designed.

Flagged for review. The maximum operating voltages above are taken from
Walsin_WR_General_Purpose_Chip_Resistor.pdf, which covers the WR12, WR08, WR06
and WR04 general purpose series only. Venatech holds no approval sheet for the High Ohm
G series and no public URL for the WR file. Confirm the figures and the datasheet URL
with Walsin before a design review.

What tolerance and TCR can I get above 10 megohms?

±1% or ±5%, and one TCR band only. All 488 parts in the High Ohm group are ≦±200 ppm/°C.
There is no ≦±100 ppm option anywhere in the group, at any size, at any value. 333 parts
are ±1% and 155 are ±5%.

The tolerance split is by size. At 0603, 0805 and 1206 there are 111 ±1% parts and 48 ±5%
parts each. At 0402 all eleven are ±5%.

Size	Parts held	±1%	±5%	TCR bands	Rated power
1206 (3216)	159	111	48	≦±200 only	1/4 W
0805 (2012)	159	111	48	≦±200 only	1/8 W
0603 (1608)	159	111	48	≦±200 only	1/10 W
0402 (1005)	11	0	11	≦±200 only	1/16 W

A 200 ppm/°C coefficient on a 100 MΩ part means 2% drift over a 100°C span. Thick film suits
a bleeder, a bias leg or a discharge path, not a precision high-value divider.

What is available at 0402, and what is not?

Eleven parts, all ±5%, all 1/16 W, spanning 11 MΩ to 30 MΩ: WF04G116 JTL,
WF04G126 JTL, WF04G136 JTL, WF04G156 JTL, WF04G166 JTL, WF04G186 JTL,
WF04G206 JTL, WF04G226 JTL, WF04G246 JTL, WF04G276 JTL and WF04G306 JTL. Every
one carries an embedded space.

What is not available at 0402: any ±1% part, anything above 30 MΩ, or any TCR other than
≦±200 ppm/°C. If the design needs 33 MΩ at 0402, it does not exist.

WF04G306 JTL uses 306 — 30 followed by six zeros — plus the trailing blank Walsin’s ±5%
E24 code requires. All eleven must carry it.

Which other series groups hold parts above 10 megohms?

Three, and together they hold more parts above 10 MΩ than the High Ohm group does. Of the
1,348 parts in Venatech’s chip resistor extract above 10 MΩ, 464 are in the High Voltage
group, 416 in the High Ohm group, 240 in the Anti-Surge group and 228 in the High Power
group.

Series group	Parts above 10 MΩ	Highest value	Example part number	Match / mismatch vs WF12G1105FTL
Thick Film High Ohm Chip-Resistor (>10MΩ)	416	100 MΩ	WF12G1105FTL	Reference part — 1206, 11 MΩ, ±1%, ≦±200, 1/4 W
Thick Film High Voltage Chip Resistor	464	100 MΩ	WF12N1105FTL	Size, value, tolerance, TCR, power all match — series group and type code mismatch
Thick Film Anti-Surge Chip Resistor	240	22 MΩ	WK25S116 KTL	Value close at 11 MΩ — size, tolerance ±10%, power 1 W all mismatch
Thick Film High Power Chip Resistor	228	100 MΩ	WF04P1006FTR	100 MΩ at 0402 and 1/8 W — size, value, TCR ≦±100, power all mismatch

The High Voltage row is the one to read twice. WF12N1105FTL and WF12G1105FTL are both
1206, both 11 MΩ, both ±1%, both ≦±200 ppm/°C and both 1/4 W. Every parametric field
matches, yet they sit in different series groups and the High Voltage part carries a UL
Safety Certification series name.

The High Power row is the surprise. WF04P1006FTR is a 0402 at 100 MΩ, ±1%, ≦±100 ppm/°C
and 1/8 W — a tighter TCR at a smaller size than the High Ohm group offers at 0402.

What should I check before committing a high ohm chip resistor?

Eight items, in order. Confirm the value exists at your case size, then the tolerance, then
accept the single TCR band. Calculate working voltage rather than dissipation. Search the
whole catalogue rather than the series group. Check for an embedded space, budget for surface
leakage, and ask Walsin for the approval sheet.

1. Confirm the value exists at the case size you want. 0603, 0805 and 1206 run 1.1 MΩ
   to 100 MΩ. 0402 runs 11 MΩ to 30 MΩ only.
2. Confirm the tolerance exists at that size. ±1% is available at 0603, 0805 and 1206.
   At 0402 the only option here is ±5%.
3. Accept ≦±200 ppm/°C, or change technology. All 488 parts sit in that one band.
4. Calculate the working voltage, not the dissipation. Above roughly 40 kΩ at 1206 the
   voltage limit governs, so rated power is not the binding constraint.
5. Search the whole catalogue, not the series group. 932 of the 1,348 parts above
   10 MΩ sit outside the High Ohm group.
6. Check whether the part number contains a space. 155 of the 488 do — every ±5% part.
   WF12G107 JTL is a different string from WF12G107JTL, and only one of them is real.
7. Budget for surface leakage. Specify the coating, the cleaning process and the
   humidity range explicitly.
8. Ask for the approval sheet. The voltage limits, the derating curve and the insulation
   resistance specification have to come from Walsin directly.

Flagged for review. Venatech holds only two Walsin chip resistor PDFs,
Walsin_WR_General_Purpose_Chip_Resistor.pdf and
Walsin_MR_Automotive_Thick_Film_Chip_Resistor.pdf, and no public URL for either. Item 8
cannot be closed from our own files. Confirm the datasheet URLs before publishing.

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FAQ

What is the highest value chip resistor Walsin makes?

100 megohms, in the Thick Film High Ohm series group, at 0603, 0805 and 1206. Venatech
holds six such parts — one ±1% and one ±5% at each size. Nothing in any Walsin thick film
chip resistor series group exceeds 100 MΩ at any case size.

Why can I not find a chip resistor above 10 megohms in Walsin’s general purpose range?

Because the general purpose range ends there. All 75,628 parts in the Thick Film General
Purpose group are 10 MΩ or below, and the approval sheet gives the range as 1 Ω to 10 MΩ.
Values above 10 MΩ live in the separate High Ohm, High Voltage, Anti-Surge and High Power
series groups.

How many Walsin chip resistors are above 10 megohms?

1,348 across the whole 234,815-part extract Venatech holds: 464 in the High Voltage group,
416 in the High Ohm group, 240 in the Anti-Surge group and 228 in the High Power group.
Searching only the group named for high ohms finds fewer than a third of them.

Is the power rating meaningful on a 100 megohm chip resistor?

Barely. A 1206 rated 1/4 W would need 5,000 V to reach rated dissipation, against a
200 V maximum working voltage for that size in Walsin’s general purpose sheet. At 200 V the
part dissipates 0.4 mW. Selection is governed by working voltage and surface leakage, not
by power.

Can I get a 1% tolerance 0402 chip resistor above 10 megohms?

Not in the High Ohm group. All eleven 0402 parts there are ±5%, 1/16 W, and span 11 MΩ to
30 MΩ. A ±1% 0402 at 100 MΩ does exist in the High Power group as WF04P1006FTR, at
1/8 W and ≦±100 ppm/°C, which is a different series group with a different specification.

What TCR is available above 10 megohms?

One band: ≦±200 ppm/°C, on all 488 parts in the High Ohm group. That is 2% drift over a
100°C span. For a precision high-value divider the thick film range is not the right
technology; for a bleeder, bias leg or discharge path it usually is.

Does the High Ohm series really only contain parts above 10 megohms?

No, despite the group name. 72 of the 488 parts are at or below 10 MΩ, and the range
actually begins at 1.1 MΩ. Those 72 are the 24 resistance values from 1.1 MΩ to 10 MΩ,
repeated at 0603, 0805 and 1206. Only the 0402 block starts above 10 MΩ.

Why does my high ohm Walsin part number have a space in it?

Because it is a ±5% part. Walsin’s E24 resistance code is two significant digits, then the
zero count, then a blank. 155 of the 488 High Ohm part numbers carry that space, all of
them ±5%. WF12G107 JTL and WF04G306 JTL must both be written with it.

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Next step

High ohm selection fails on voltage and on search path, not on resistance. Send the BOM
lines and Venatech Limited, an authorised Walsin distributor in Hong Kong, will return every
Walsin part above 10 MΩ at that case size and tolerance, including the ones outside the High
Ohm series group.

Send your BOM to Venatech · Browse the
Walsin chip resistor range · Read
Chip resistor power rating by case size and
Anti-surge chip resistors.

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