Walsin Thin Film Resistor Wattage: 15,173 of 15,204 Specifications Above 0201 Come in Two Rated Powers, Chosen by One Letter

Walsin thin film resistor wattage is a second choice hidden inside the TCR choice. We grouped the WF precision rows by case size, resistance, tolerance and TCR. Above 0201, 15,173 of 15,204 groups hold two part numbers at two different rated powers, and the only thing between them is the fifth character.

Pick a TCR grade from the Walsin thin film export and you have not picked a wattage. Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 parametric export files published by Walsin Technology (Walsin). This post is measured from the eight Thin_Film_Precision_Chip_Resistor_WF_Series_*.xlsx sheets that hold rows, 58,314 part numbers, of which the letters Q, R, T and U account for 35,887. Every part number below is real. We hold no thin film datasheet, so what these letters mean is read from the data and nothing else.

How many Walsin thin film specifications come in two rated powers?

Most of them. We grouped the 35,887 rows by case size, resistance, tolerance and TCR grade, which gave 18,244 specifications. 16,817 of them (92.2%) hold exactly two part numbers at two different rated powers, 413 hold three part numbers at two powers, and 1,014 hold one. Not one pair in the whole catalogue shares a wattage.

We have not seen this counted anywhere. Our earlier work counted the 413 pairs that are identical on all five published fields, which are the other side of this coin. Here we count the pairs that differ on exactly one field, and there are 16,817 of them. For the footprint ladder itself see thin film resistor power rating by case size.

Which part number letters carry the full wattage and which the lower one?

Q and R carry the full wattage; T and U carry one step less. We cross-tabulated position five of the part number against TCR and Rated Power on every one of the 30,381 rows above 0201. Q is ≦±50 ppm/°C and R is ≦±25 on all 7,602 of their rows, at the footprint’s full wattage; T is ≦±50 and U is ≦±25, at the next wattage down. The letter pair decides the wattage and the letter within the pair decides the TCR.

The table is the 10 kΩ position at ±0.01% for the two footprints with the widest step. The last column judges each part against a generic incumbent: 1206, 10 kΩ, ±0.01%, ≦±25 ppm/°C, rated 1/8 W.

Of the four 1206 parts, exactly one matches an incumbent specified at ≦±25 and 1/8 W on every published field. A cross that stops at “≦±25 ppm/°C, 1206, 10 kΩ” returns two parts, and one of them runs at twice the rated power. Whether that is an improvement or a cost depends on what your design needs, and the export cannot tell you.

How big is the wattage step at each footprint?

Not constant. We divided the lower wattage by the full wattage at every footprint. The step is 0.625 at 0201, 0402, 0603 and 1210; 0.8 at 0805; 0.5 at 1206; 0.667 at 2010; and 0.75 at 2512. 1206 loses exactly half, the most of any size, and 0805 loses the least.

The ladder overlaps. 1/8 W is the lower wattage at 1206 and the full wattage at 0805, and 1/10 W is the lower wattage at 0805 and the full wattage at 0402 and 0603. So a 1206 U part and an 0805 Q part carry the same 1/8 W on the label from two different footprints. See chip resistor power rating by case size for the same ladder on thick film.

Where does the two-wattage pairing break above 0201?

At 31 cells out of 15,204. We listed every group above 0201 with one part number or three. 27 are ≦±25 ppm/°C full-wattage R parts with no U twin: 19 have no U part number in the export at all, and 8 have a U part number whose Resistance cell reads 100 times too large. The other four are the two 98.8 Ω and 100 Ω cells at 0402, where the code conflict we published earlier splits a pair into a single and a triple.

So for 1210 and ≦±25 ppm/°C at 1/4 W, a design on 101 Ω or 931 Ω has no part. Every one of the 8 wrong-cell rows at 1206 is among the ten resistance-code disagreements we reported in the position-five post, so the twin exists as a part number but not as a searchable row at that value. A filter on 221 Ω at 1206 returns WF12R2210TTL and not its twin. To check any other pair, see the free cross reference.

What changes at 0201?

The letters rearrange. We read all 5,506 rows at 0201 on their own. Only 1,644 of 3,040 specifications (54.1%) are plain pairs, 411 are triples, and 985 stand alone. The reason is that 0201 has no ±0.01% part at all, and that its R letter carries two TCR grades while its Q letter carries one.

At ±0.1%, Q, R and U are all ≦±25 ppm/°C and T is the only ≦±50 part. The three ≦±25 parts are the 411 triples, WF02Q1002BTL and WF02R1002BTL at 1/20 W and WF02U1002BTL at 1/32 W at 10 kΩ; the Q and R twin inside each triple is one of the 413 five-field pairs we published earlier. T has no ≦±50 partner at that tolerance and stands alone on 426 values. At ±0.5% and ±1%, Q and U are ≦±25 and R and T are ≦±50, which gives 411 Q-U pairs (WF02Q1002DTL, WF02U1002DTL) and 411 R-T pairs (WF02R1002DTL, WF02T1002DTL) at each tolerance. The rest stand alone: Q and R below 100 Ω, T and U above 10 kΩ. See the position-five post for the TCR side of this.

Why does the lower-wattage twin exist?

We do not know. The export does not say, and we will not guess. We checked every column of both members of the pair across all 15,173 pairs above 0201: Series, Size, Resistance, Tolerance and TCR are identical, Packaging reads 7" reel taping and Termination reads Sn base (Lead free) on both. The only published field that separates the two parts is Rated Power.

What should a cross do with a wattage pair?

Show both, and say which field differs. A cross on size, value, tolerance and TCR returns two parts in 92.2% of cases, and a tick on either hides the choice. Three rules follow from the counts.

1. Match the wattage explicitly. If your incumbent is rated at the lower step, U or T is the match and R or Q is a mismatch on power in your favour. If it is rated at the higher step, the U twin is a mismatch against you.
2. Do not search by TCR and footprint alone. 15,173 specifications above 0201 return two parts that differ by one letter.
3. Check for the 27 exceptions. At 1206 and 1210 a ≦±25 ppm/°C search can return a single part where a twin might be expected.

We hold 28 Walsin datasheets, 451 pages, and none covers thin film. What is in Hong Kong is on ready stock, a dated snapshot of 1,125 part numbers as at 23 September 2026, and the range itself is on the thin film page.

The short version

Above 0201, 15,173 of 15,204 WF thin film specifications (size, value, tolerance, TCR) come in two part numbers at two rated powers, one letter apart: Q and R at the footprint’s full wattage, T and U one step lower. The step is 0.5 at 1206 and 0.8 at 0805. Across all footprints 16,817 of 18,244 specifications (92.2%) are pairs, and not one pair shares a wattage. 27 values at 0603, 1206 and 1210 have an R part with no U twin. The export gives no reason for the lower wattage, and we hold no thin film datasheet. A cross that returns one part for your specification is hiding the other. Qualification stays with you.

Send us the size, value, tolerance, TCR and wattage off your drawing and we will show you both members of the pair and which field differs. And a question back: when your BOM said “thin film, 1206, 10 kilohm, 25 ppm”, which of the two wattages did you buy?

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