Chip Resistor Part Marking for the United States: 14 of 19 Case Sizes in Walsin’s Export Have No Marking Statement

Chip resistor marking is defined for only 5 of the 19 case sizes in Walsin’s export. We read all 28 datasheets for United States incoming-inspection plans: two resistor sheets define top marking, the 26 MLCC sheets never use the word, and 70,597 of 234,815 resistor rows sit in sizes no sheet mentions.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds 28 datasheets from Walsin Technology (Walsin), 451 pages. This post is written from the MARKING table of the two chip resistor sheets, Walsin_WR_General_Purpose_Chip_Resistor.pdf and Walsin_MR_Automotive_Thick_Film_Chip_Resistor.pdf, from a text search of the 26 MLCC PDFs, and from the 234,815 rows of the 137 chip resistor export files. Every part number is real. A US inspector reading a reel label against a body mark needs to know which sizes have a mark to read. We counted.

Which Walsin datasheets define part-top marking, and for which case sizes?

Two datasheets, five sizes. The WR general purpose sheet (ASC_WR_V24, SEP 2016) defines marking for 1206, 0805 and 0603 and states “N0 MARKING” for 0402. The MR automotive sheet (ASC_MR_V13, Mar 2024) does the same and adds 1210. The other 26 sheets are MLCC datasheets, and the word “marking” appears in none of their 431 pages.

Case size	WR sheet (page 4)	MR sheet (page 4)	Export rows, all prefixes	Match / mismatch between the two sheets
1210	no statement	3-digit at 5% and Jumper, 4-digit at 1%	18,149	Mismatch: MR defines it, WR is silent
1206	3-digit at 5%, 4-digit at 1%	3-digit at 5%, 4-digit at 1%	37,566	Match
0805	3-digit at 5%, 4-digit at 1%	3-digit at 5%, 4-digit at 1%	38,044	Match
0603	3-digit at 5% and 1%	3-digit at 5% and 1%	42,374	Match
0402	“N0 MARKING”	“NO MARKING”	28,085	Match on meaning. Mismatch on spelling: WR prints the digit zero
14 other size strings	none	none	70,597	no statement in either sheet

We have not seen this counted anywhere: 14 of the 19 distinct Size strings in the chip resistor export are in no marking table, and they hold 30.1 percent of the rows. The WR sheet’s zero in “N0 MARKING” is a typing slip in an otherwise matching 0402 line.

How many case sizes in the export have no marking statement?

14 of 19, and 70,597 rows. We parsed all 137 files and read the Size column as printed. The 14 strings are 2512 (22,154 rows), 2010 (21,228), 0201 (17,827), 1218 (3,318), 0612 (1,725), 1225 as 3264 (1,708), 1020 (878), 01005 (755), 06028 (555), 02014 (194), 0201*2 (194), 1225 as 3263 (47), 0306 (10) and 0815 (4).

That counts string spellings: 1225 appears under two metric codes, and three array formats are listed as sizes. Count physical footprints and the number is lower; count the way a selector sees the column and it is 14. The table above is the reason the selector cannot answer “is this part marked?” for 30 percent of the catalogue.

The picture changes again when you count by sheet and prefix, which is how the ordering key decodes. 234,815 rows split four ways:

Row class	Rows	Share	Match / mismatch against “a marking statement exists for this exact prefix and size”
WR or MR prefix, size with a digit rule on its own sheet	25,474	10.8%	Match
WR or MR prefix at 0402, sheet states no marking	7,752	3.3%	Match: the statement is “none”
WR or MR prefix, size its own sheet does not tabulate	29,531	12.6%	Mismatch: WR 25,655, MR 3,876
The 11 other prefixes, no resistor sheet held	172,058	73.3%	Mismatch: no sheet at all

73.3 percent of the catalogue has no marking statement because there is no datasheet. We hold none for the other 11 prefixes, which include the high precision, anti-surge, current sense, array and high voltage lines. Counting is by part-number prefix, WR12 and MR12 style, because that is what the sheets name themselves by. 20,578 of the WR-prefix rows sit in series whose export name says Automotive; we count them as WR on prefix and flag that choice below.

Which real part numbers get which mark, and which get none?

Marks follow the sheet’s rule; the sheet gives worked examples. We applied the rule to real export rows and checked each against the sheet’s own example. We have not read a printed part. The 17.8 ohm 0603 row gets 25X because the sheet prints “17.8Ω=25X”; the 10 ohm 1206 one percent row gets 10R0 because the sheet prints that for 10.

Part number	Size	Tolerance and value	Mark the sheet’s rule gives	Match / mismatch against the sheet’s worked example	Your incumbent part (fill in)
WR12X10R0FTL	1206	±1%, 10.0 Ω	10R0 (4-digit)	Match: the sheet prints 10 Ω as 10R0
WR06X17R8FTL	0603	±1%, 17.8 Ω	25X (E96 code and index)	Match: the sheet prints 17.8Ω=25X
WR08X100 JTL	0805	±5%, 10 Ω	100 (3-digit)	Match: the sheet prints 10 Ω as 100
MR06X17R8FTL	0603	±1%, 17.8 Ω	25X	Match with the WR row; the MR sheet prints the same example
WR10X1001FTLV	1210	±1%, 1000 Ω	none stated by the WR sheet; MR rule would be 4-digit	Mismatch: WR prefix, MR-only size
WR04X10R0FTL	0402	±1%, 10.0 Ω	“N0 MARKING”	Mismatch against the 0603 row: no mark
MR04X10R0FTL	0402	±1%, 10.0 Ω	“NO MARKING”	Mismatch against the 0603 row: no mark
WR02X10R0FTL	0201	±1%, 10.0 Ω	no statement	Mismatch: size absent from both sheets
WR25X10R0FTL	2512	±1%, 10.0 Ω	no statement	Mismatch: size absent from both sheets
MR20X10R0FTL	2010	±1%, 10.0 Ω	no statement	Mismatch: size absent from MR’s table

The stock snapshot is the practical side. The Hong Kong ready-stock snapshot as at 23 September 2026 lists 255 chip resistor part numbers; 250 match an export row once embedded spaces are ignored. 152 are WR parts in 1206, 0805 or 0603, where a digit rule exists. 78 are WR at 0402, where the sheet says none. 6 are WR in 0201 or 2512, and 14 carry other prefixes. Ready stock is a dated snapshot and not a live feed; these are part-number counts.

What does the export carry about marking?

Nothing. We checked the column headers of all 203 export files for “mark”, “print” and “label”. The only hit is Remark in 18 MLCC files, which holds a customised-product note on 432 of its 435 filled rows and is not marking. The chip resistor files carry 10 columns: Part Number, Series Group, Series, Size, Resistance, Tolerance, TCR, Rated Power, Packaging and Termination.

So a selector cannot filter on “has a body mark”. The reader has to infer it from size and prefix, which is the exercise above. For MLCC there is no inference to make: the 26 MLCC sheets carry no marking statement, and the export has 16 clean case-size codes plus one corrupted cell, none with a mark field. We hold no document that says whether Walsin MLCC are marked or unmarked; “not in the documents we hold” is the whole of what we can say, and we will not guess.

A small copy artefact points the same way. The MR sheet’s 0603 E24 line reads “As 0603 WR06X 5%”, naming a WR part stem inside an MR document. The WR sheet’s marking table lists 5% and 1% only, and the export has 47 WR rows with Tolerance Jumper; the MR table names “Jumper (0Ω)” and the export has 18 MR Jumper rows. The WR marking table does not name Jumper, so the 47 WR Jumper rows have no stated rule.

Does the 0603 one percent rule leave any value ambiguous?

Yes, for six values. The 0603 one percent rule has two routes: E24 values follow the 5% three-digit rule, and E96 values use a two-digit code plus an index letter. We built the E96 list from the sheet’s 96-entry code table and the E24 list from the standard series, and tested every 0603 one percent WR and MR row. 344 of 6,392 carry a mantissa both series contain: 1.00, 1.10, 1.30, 1.50, 2.00 or 7.50, in any decade.

The sheet does not say which route governs those. WR06W1R00FTL and MR06W1R00FTL are both 1.00 Ω, 0603, ±1%, and both lists claim 1.00. We found no row outside both lists, so Remark 3, “no marking for the items are not under E-24 and E-96”, excludes nothing in WR or MR 0603 one percent data. In the same 6,392 rows, 5,040 are E96 only and 1,008 are E24 only; those 6,048 follow one route and do not conflict.

What should a US incoming-inspection plan do about unmarked sizes?

Three things. First, do not build a “read the body mark” step for 0402 or smaller: 28,085 rows are 0402 and both sheets say no marking, and 755 are 01005 with no statement. Second, key inspection to the reel label and date code, not the part. Third, map each part number to a row class above before writing the plan. 73.3 percent of rows have no sheet to cite.

The reader’s own check is five minutes: pull the Size column, remove the five sizes in the table, count what is left. A related caution on authenticity is in counterfeit passive components and authorised sourcing, and the E24 and E96 value logic is in E24 vs E96 Walsin resistor values. The resistor range sits on the chip resistor page. We will not tell you a body mark proves a part. We will show you where a mark exists to be read.

The short version

We counted: two datasheets define marking, for 5 sizes (1210, 1206, 0805, 0603 and 0402, the last as “no marking”). The export has 19 Size strings; 14 have no statement, 70,597 rows (30.1%). By prefix, 25,474 rows (10.8%) sit where a digit rule is printed, 7,752 are 0402 with none, 29,531 are WR or MR in sizes their sheet omits and 172,058 (73.3%) have no resistor sheet. The 26 MLCC sheets never use the word marking. 344 of 6,392 0603 one percent rows carry a value both E24 and E96 routes claim. We hold 28 Walsin datasheets, 451 pages, sent on request. Confirm against both datasheets and qualify in your own circuit.

Send us the chip resistor part numbers on your US bill of materials and we will tell you which sheet, if any, defines the mark on each. Venatech Limited, Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong, (852) 2628 4777, or paste up to 500 part numbers into our free cross-reference tool. One question back: if your incoming inspection reads body marks, what does it do with an 0402?

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Frequently asked questions

<!– wp:rank-math/faq-block {"questions":[{"id":"faq-question-01","title":"Which Walsin chip resistor sizes are marked?","content":"The WR and MR datasheets define marking for 1206, 0805 and 0603, and MR adds 1210. Both state no marking for 0402. Neither sheet mentions the other 14 Size strings in the export, which hold 70,597 of 234,815 rows. We have not read a printed part, so this is the datasheet position only.”,”visible”:true},{“id”:”faq-question-02″,”title”:”Do Walsin 0402 chip resistors carry a marking?”,”content”:”Not according to either sheet. The WR sheet prints \”N0 MARKING\” and the MR sheet prints \”NO MARKING\” for 0402. The export has 28,085 rows at 0402, of which 7,752 are WR or MR prefix. For the other prefixes we hold no sheet at all.”,”visible”:true},{“id”:”faq-question-03″,”title”:”How do I read a Walsin 3-digit or 4-digit resistor marking?”,”content”:”Three digits at 5 percent: the first two are digits and the third the multiplier, so 10 ohm reads 100. Four digits at 1 percent in 1206 and 0805: 10 ohm reads 10R0. For 0603 at 1 percent the sheet uses a two-digit E96 code plus an index letter, so 17.8 ohm reads 25X.”,”visible”:true},{“id”:”faq-question-04″,”title”:”Does Walsin define marking for its MLCC?”,”content”:”Not in the documents we hold. We searched all 26 MLCC datasheets, 431 pages, and the word marking does not appear. The export has no marking column either. We do not state whether the parts are marked, and we will not guess.”,”visible”:true},{“id”:”faq-question-05″,”title”:”Can I filter the Walsin export by whether a part is marked?”,”content”:”No. We checked the headers of all 203 export files; none names marking. The only match for the substring is Remark, which holds customised-product notes on 432 of its 435 filled MLCC rows. You must infer marking from size and prefix, as this post does.”,”visible”:true},{“id”:”faq-question-06″,”title”:”Are any 0603 one percent values ambiguous under the sheet’s marking rule?”,”content”:”Six mantissas are, in our reading: 1.00, 1.10, 1.30, 1.50, 2.00 and 7.50 belong to both E24 and E96. 344 of 6,392 WR and MR 0603 one percent rows carry one. The sheet does not say which route applies. We flag it for Walsin and do not guess.”,”visible”:true}],”listStyle”:””,”titleWrapper”:”h3″,”titleCssClasses”:””,”contentCssClasses”:””,”sizeSlug”:””} –>

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