Chip Resistor Power Rating Selection: 19 of 63 Case-Size-by-Watt Cells Exist

Chip resistor power rating selection on the anti-surge shelf is a staircase with real gaps. We gridded Walsin’s 7 anti-surge case sizes against its 9 rated powers. Only 19 of 63 cells are populated — 30.2% of the grid — and no case size reaches more than 5 of the 9 wattages.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 14 files matching Thick_Film_Anti_Surge_Chip_Resistor_*.xlsx in Walsin Technology (Walsin)’s chip resistor export — 17,180 real part numbers. This post grids every one of them by case size and rated power. Every part number below is real and came out of that grid.

Is Walsin’s anti-surge export split by wattage, by tolerance, or both?

By tolerance only — rated power is not a filename-level filter at all. We established in a companion post that the 14-file suffix set (0_5, 1, 5, 10, 20, and 9 empty ones) encodes tolerance, verified against the EIA letter in all 17,180 part numbers. Here is what that means for wattage: the general-purpose shelf splits by tolerance and wattage in its own filenames — Thick_Film_General_Purpose_1_1W.xlsx, ..._1_1_4W.xlsx, ..._1_1_8W.xlsx and eight more. Anti-surge does not. We opened the single ±5% anti-surge file, Thick_Film_Anti_Surge_Chip_Resistor_5.xlsx, and it alone spans all 9 rated powers used anywhere in the family, in one 4,085-row sheet.

How many of the 63 possible case-size-by-wattage cells actually exist?

19 of 63 — 30.2%. We crossed the 7 case sizes where anti-surge exists (0402 through 2512) against the 9 distinct rated powers the family uses (1/10 W, 1/8 W, 1/5 W, 1/4 W, 1/3 W, 1/2 W, 3/4 W, 1 W, 2 W) and counted which of the resulting 63 cells hold at least one part number.

We counted every cell in this grid and have not seen that count published anywhere else. No row sums to more than 5, and the richest case size (0805) still misses 4 of the 9 wattages used in the family.

Which anti-surge case size offers the most rated-power choices?

0805, with 5 of the 9 wattages — but one of those 5 is a near-empty cell, which we flag below. The next richest sizes, 0603, 1206 and 2010, each carry only 3. The smallest size, 0402, carries exactly 1: every one of its 830 rows is rated 1/5 W, with no alternative wattage stocked at that footprint at all.

Does one series map exactly one power rating to each case size?

Yes — Thick Film Triple Power Surge Chip Resistor (Automotive) does, with no exceptions but one. These rows live inside Thick_Film_Anti_Surge_Chip_Resistor_1.xlsx and ..._5.xlsx, Walsin’s own ±1% and ±5% tolerance files, not a dedicated series file. We grouped its 5,810 rows by case size and found exactly 830 parts at every one of the 7 sizes, each size locked to a single rated power: 0402 at 1/5 W, 0603 at 1/3 W, 0805 at 1/2 W, 2010 at 1 W and 2512 at 2 W, with 1206 and 1210 both landing on 3/4 W.

A second series, Thick Flim Power Surge Chip Resistor (Automotive), inverts what a buyer would expect from size alone: its smaller case size, 0603, is rated 1/3 W, while its larger case size, 0805, is rated only 1/4 W — the only two sizes this series reaches, and the bigger one carries the lower rating.

Where is the gap a 1206 design at 1/2 watt actually falls into?

Nowhere in this family. We checked the 1206 (3216) row of the grid directly, across Thick_Film_Anti_Surge_Chip_Resistor_1.xlsx, ..._5.xlsx, ..._10.xlsx and ..._20.xlsx: it holds 1/3 W, 1/4 W and 3/4 W, with zero rows at 1/2 W, 1/8 W or 1/10 W. A design that needs an anti-surge 1206 rated at exactly 1/2 W — a rating general purpose does stock at 1206, per Walsin’s own general-purpose export — has to step up to 3/4 W or down to 1/3 W; there is no part number in between in the data we hold.

How thin is the smallest populated cell in the whole grid?

Three rows out of 3,929 at that case size. The 0805-at-1/10 W cell, one of the 5 that make 0805 the richest row in the grid, holds exactly 3 part numbers: WF06S1R0 JTL, WF06S1R1 JTL and WF06S1R2 JTL, all ±5% tolerance in the baseline Thick Film Anti-Surge Chip Resistor series. That is 0.08% of the 0805 rows in the family. Treat “0805 covers 5 wattages” as technically true and practically thin at the low-power end.

What should a buyer do when the exact wattage step is missing?

Step to the nearest populated cell and confirm it clears your design margin, rather than assuming the gap will be filled later. The trade press has reported passive component lead times stretching through 2026 as AI server and EV volumes compete for the same manufacturing capacity, so knowing which cells in a family are actually stocked — not just which case sizes exist — is the difference between a fast second source and a part that is never coming.

1. Tell us the case size and the exact wattage you need. We will state plainly whether that cell is populated in our extract, rather than imply a part exists because the case size does.
2. Cross the whole BOM in one pass. The free cross-reference tool takes up to 500 pasted part numbers or an Excel or CSV file, decodes 18 manufacturers’ part numbers and matches against 800,000+ crossable Walsin part numbers, stating every difference field by field.
3. Check what is physically in Hong Kong on ready stock, a dated snapshot as at 23 September 2026, before committing a production slot to a thin cell.

For the construction behind the anti-surge power advantage and the fields the export does not publish, see Anti-surge chip resistors. For how a single tolerance letter maps to six wattage steps across the wider catalogue, see Chip resistor rated power steps: one letter, six wattages. The full line is on the Walsin chip resistor range page.

The short version

Chip resistor power rating selection on Walsin’s anti-surge shelf is a 7-by-9 grid, and only 19 of the 63 possible case-size-by-wattage cells are populated. 0805 is the richest at 5 of 9, and even that includes a 3-part sliver at 1/10 W. 0402 holds exactly 1 wattage. One series, Thick Film Triple Power Surge (Automotive), maps one power to each case size with near-perfect discipline; another inverts the expected size-to-power relationship entirely. A 1206 at 1/2 W simply is not in the data we hold.

Send us your case size and target wattage and we will tell you which cell of this grid it falls in — populated, thin, or empty — before you spend a design cycle assuming the step exists.

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