Thin Film vs Thick Film Case Size for Mexico: Only 4,780 of 11,422 Size-and-Value Pairs Sit on Both Shelves

Thin film vs thick film case size looks like a clean overlap: both Walsin families cover the same eight footprints. It is not. We counted every size-and-resistance pair: 11,422 exist, and only 4,780 (41.9 percent) are on both shelves.

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If your drawing in Mexico says 0603 and 10 kilohm, either family can fill it. If it says 0603 and 2.70 ohm, only one can. Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the chip resistor and thin film export files published by Walsin Technology (Walsin). This post is written from 234,401 distinct chip resistor part numbers and 93,914 thin film part numbers, with embedded spaces removed from the first set. Every part number below is real, every count is of part numbers and never of pieces, and the technology of each row is read from the export file it came from rather than from its prefix.

How many size-and-value pairs do Walsin thin film and thick film share?

Fewer than half. We parsed the resistance of every row at the eight case sizes both exports list and counted distinct pairs of case size and resistance value. Thick film holds 8,053 pairs, thin film holds 8,149, and only 4,780 appear in both. 3,273 are thick film only and 3,369 are thin film only, out of a union of 11,422. The overlap is 41.9 percent of everything either family offers at these footprints.

Case size	Thick film part numbers	Thin film part numbers	Thin film share of the two	Values on both	Thick film only	Thin film only	Match / mismatch
0201	17,827	5,506	23.6%	304	522	243	Mismatch — 522 thick film values have no thin film twin
0402	27,961	6,359	18.5%	501	561	399	Mismatch — fewer than half the thick film values are matched
0603	42,374	7,562	15.1%	604	462	454	Mismatch — the largest thick film shelf, the lowest thin film share
0805	38,044	7,985	17.3%	634	446	454	Mismatch
1206	37,566	29,217	43.7%	719	369	454	Mismatch — thin film lists more values than thick film
1210	18,149	7,216	28.4%	642	324	455	Mismatch
2010	20,938	22,246	51.5%	650	324	455	Mismatch — thin film has more part numbers than thick film
2512	22,154	7,823	26.1%	726	265	455	Mismatch

We have not seen this counted anywhere. The two families do not nest. Thin film is not a precision subset of thick film’s ladder; it carries 3,369 pairs of its own, and thick film carries 3,273 that thin film cannot fill. For the technology comparison itself, see thin film against thick film chip resistors.

Which chip resistor case sizes does thin film not offer at all?

Eleven of the 19. We read the Size column of every chip resistor row and found 19 distinct size strings; the thin film export uses 8 of them. The other 11 strings hold 9,388 thick film part numbers, 4.0 percent of the 234,401, and thin film has no row at any of them. The 8 shared sizes hold the remaining 225,013.

Size string	Part numbers	Series group	A real part	Match / mismatch against thin film
01005 (0402)	755	General purpose	WR01X10R0FDL	Mismatch — smaller than any thin film footprint
02012, 02014, 0602*8	194, 194, 555	Resistor arrays	WA02F100JTL	Mismatch — array footprints, no thin film array in the export
0306 (0816), 0612 (1632), 1225 (3263)	10, 1,725, 47	Metal low-ohm current sense, wide terminal	WW06YR001FTL	Mismatch — current sense, milliohm range
0815 (2037), 1020 (2550), 1225 (3264)	4, 878, 1,708	Low-ohm sense, wide terminal power	WK25L1R00FTL	Mismatch — power footprints
1218 (3248)	3,318	General purpose, low-ohm sense	MR18W1R00FTL	Mismatch — the largest thick film only size

Two of these strings, 1225 (3263) and 1225 (3264), share the imperial code 1225 under two metric codes; that problem is covered in one case size, two metric codes. The long list of case-size notations is in passive component case sizes, imperial and metric.

Where does thin film outnumber thick film, and why?

At 2010 and nearly at 1206, and in both cases because of one series. We counted thin film part numbers by series at each size. At 2010 thin film has 22,246 part numbers against 20,938 for thick film, and 14,810 of the thin film rows (66.6 percent) are the anti-sulfuration SF series. At 1206 thin film has 29,217, and 20,520 (70.2 percent) are the tantalum nitride MF series. Everywhere else thick film is the larger shelf.

So a high thin film share at one footprint does not mean more choice in the thing you are filtering on. At 2010 the SF series publishes tolerances from plus or minus 0.05 to 1 percent, while the WF precision series at that size publishes only plus or minus 0.01 percent. The count is real and the interpretation is series-by-series; the thin film grid is in the 26 live TCR and tolerance cells.

Why do 3,335 of 3,369 thin-film-only pairs use values thick film does not list?

Because the two ladders have different step sizes. We reduced every resistance to its three significant digits, so 10.2 ohm and 1,020 ohm both read 102. Thin film uses 205 distinct three-digit values and thick film uses 137 at the shared sizes; 115 are common, 90 belong to thin film alone and 22 to thick film alone. 3,335 of the 3,369 thin-film-only pairs sit on one of those 90 thin film steps. Only 34 are a shared step that thick film simply does not offer at that footprint.

The range also differs. We read the lowest and highest value at each size.

Case size	Thick film lowest and highest	Thin film lowest and highest	Match / mismatch
0201	0 ohm (jumper) to 10 megohm	27 ohm to 12 kilohm	Mismatch — thin film stops three decades short
0402	0 ohm to 100 megohm	10 ohm to 255 kilohm	Mismatch
0603	0 ohm to 100 megohm	4.7 ohm to 1 megohm	Mismatch
1206	0 ohm to 100 megohm	1 ohm to 2.49 megohm	Mismatch
2512	0 ohm to 100 megohm	1 ohm to 3 megohm	Mismatch

A value you can only find in one export is not a defect. It is a reason to stop asking which family is “better” and ask which cell your resistance falls in.

In a cell both families fill, what actually differs?

Almost always the tolerance and the temperature coefficient, and in one direction. We took the best published limit for every one of the 4,780 shared cells. Thin film’s best temperature coefficient beats thick film’s in 4,713 cells and ties in 67; it is never worse. On tolerance, thin film is tighter in 4,476 cells, ties in 237, and is looser in 67, all at 0201.

Cell	Thick film part	Thin film part	Match / mismatch
0603, 10 kilohm	WK06K1002DTL — plus or minus 0.5%, not more than plus or minus 50 ppm per degree, 1/10 W	WF06B1002TTL — plus or minus 0.01%, not more than plus or minus 3, 1/10 W	Match on size, value and power. Mismatch on tolerance and temperature coefficient
1206, 10 kilohm	WK12K1002FTL — plus or minus 1%, not more than plus or minus 50, 1/4 W	MF12R1002FTL — plus or minus 1%, not more than plus or minus 25, 2/5 W	Match on tolerance. Mismatch on temperature coefficient and power
2010, 10 kilohm	WF20H1002BTL — plus or minus 0.1%, not more than plus or minus 100, 1/2 W	SF20R1002FTL — plus or minus 1%, not more than plus or minus 25, 3/4 W	Mismatch — thin film here is the looser tolerance
0201, 27.1 ohm	none in the export	WF02Q27R1FTL	Mismatch — thin film only
0201, 97.6 kilohm	WR02X9762FGL	none in the export	Mismatch — above the 12 kilohm thin film ceiling

The 2010 row is the one to remember. Thin film is not the tighter option in every cell. We hold no thin film datasheet and only two resistor datasheets, WR and MR, so every figure in this table comes from the export and must be confirmed on Walsin’s own site.

The short version

Walsin’s thick film and thin film chip resistors share 8 case sizes and 4,780 of 11,422 size-and-value pairs. Thick film has 3,273 pairs of its own, thin film 3,369. Eleven of 19 size strings, 9,388 thick film part numbers, have no thin film row. Thin film outnumbers thick film only at 2010 and is led by one series each at 2010 and 1206. 3,335 of the 3,369 thin-film-only pairs use a value step thick film never lists. In shared cells thin film wins temperature coefficient in 4,713 of 4,780 and loses tolerance in 67. We will not tell you a part is equivalent. We will show you where it differs.

Send us the size and resistance on your drawing and we will tell you which shelf holds it, or both. Paste up to 500 part numbers into the free cross-reference tool, and see what is physically in Hong Kong on ready stock, 1,125 part numbers as at 23 September 2026, a dated snapshot and not a live feed. And a question back: when your BOM line says “thin film or thick film, either is fine”, which of the 4,780 cells did you actually mean?

The thin film range sits on the thin film page. We hold 28 Walsin datasheets, 451 pages, sent on request, none for thin film. Confirm against both datasheets and qualify in your own circuit. Venatech Limited, Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong, (852) 2628 4777.

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Frequently asked questions

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