Walsin Part Number Not Found: 109 Codes We Hold With No Row in Any Export

We hold 109 stock codes that return a Walsin part number not found against all 203 of Walsin’s parametric export files. We published 101 on 6 October 2026. We re-measured cell by cell and the figure is 109 — the other 8 matched our own stock file, not Walsin’s catalogue. 73 of the 109 are Y5V.

---

Venatech Limited, an authorised Walsin distributor in Hong Kong, is publishing a case where our own two data sources disagree with each other. This post is measured from the Hong Kong in-stock workbook — a single .xlsx sheet read with header=3, dated 23 September 2026 in row 2 — against every sheet in Walsin Technology (Walsin) 203-file parametric set, including 00_ALL_MLCC_parts_combined.xlsx. Every part number below is real. Where a code has no matching row we say so on the same line, because that absence is the finding.

Why does a Walsin part number we hold return not found in the catalogue?

Because the stock register and the parametric catalogue are built by different people for different purposes. We took all 1,125 catalogue codes from the 23 September 2026 snapshot and searched every cell of all 203 export files — not only the Part Number column, every column. 109 codes returned nothing anywhere. That is 9.7% of the shelf invisible to any tool that reads Walsin’s published data, including our own cross-reference tool.

What we searched	Scope	Result
Catalogue codes in the dated snapshot	1,125	1,016 found, 109 with no matching row
Export files searched	203	120 non-empty, 83 return zero rows
Distinct part numbers across those files	359,136	None of them matches the 109
Columns searched per file	all	Not just Part Number — every cell, to rule out a column-name miss
MLCC rows in the combined export	24,026 rows, 23,601 distinct	425 duplicate rows, so row count overstates coverage

A part absent from the export is not a part we cannot supply. It is a part the automated path cannot describe. That distinction is the whole post, and nobody else publishes it about their own stock list.

What are the 109 codes, grouped by prefix and case size?

Overwhelmingly small-case chip MLCC. We grouped all 109 by what the code’s own prefix declares. 92 are size-prefixed chip MLCC codes, 12 are series-prefixed MLCC codes, and 5 are chip resistor or resistor-array codes. Within the 92, 0805 is the single biggest group at 22 codes, followed by 1812 at 15, and 1206 and 1210 at 14 each. Not one 2225, 1825, 2211, 1111 or 01R5 code is affected.

Prefix group	What the prefix implies	Codes with no matching row
0805	chip MLCC, 2012 metric	22
1812	chip MLCC, 4532 metric	15
1206	chip MLCC, 3216 metric	14
1210	chip MLCC, 3225 metric	14
0603	chip MLCC, 1608 metric	11
0402	chip MLCC, 1005 metric	9
1808	chip MLCC, 4520 metric	4
0201	chip MLCC, 0603 metric	2
2220	chip MLCC, 5750 metric	1
RF	microwave MLCC	5
SH	soft termination, Ag-poly	3
TT	low profile MLCC	2
HH	high Q and low ESR	1
S2	safety certificated X1/Y2	1
WF, WR, SR	thin film, general purpose and array chip resistor	5

By the dielectric letter in position five, the 104 MLCC-line codes break down as 73 Y5V, 21 NP0, 7 X7R, 2 X5R and one malformed code, 08052R152K501BA, whose fifth character is a digit. Note that the letter only means a dielectric on an MLCC code: WR12X0000FTL carries an X in the same position and is a 1206 zero-ohm chip resistor, which is exactly the kind of collision that makes prefix parsing unsafe without the catalogue behind it.

Why is two thirds of the gap one dielectric?

Because Walsin’s parametric export barely publishes Y5V at all. We counted the dielectric column across all 24,025 real rows of 00_ALL_MLCC_parts_combined.xlsx: exactly 2 rows are Y5V, 1206F474M500 and 1206F474Z500, both 470 nF at 1206 and 50 Vdc. Against that, 73 of our 109 unmatched codes carry the F dielectric letter. We have not seen this counted anywhere. The dielectric is not missing from Walsin’s range — it is missing from Walsin’s published data, and the shelf is the proof.

Code	Prefix implies	What the code decodes to	Walsin export	Match / mismatch
0402F104Z100	0402 Y5V	100 nF, −20/+80%, 10 Vdc	no matching row	Mismatch — dielectric effectively unpublished
0805F474Z500	0805 Y5V	470 nF, −20/+80%, 50 Vdc	no matching row	Mismatch — same value as the only 2 Y5V rows, different case
0805F685Z100	0805 Y5V	6.8 µF, −20/+80%, 10 Vdc	no matching row	Mismatch — no 0805 Y5V row exists at any value
1210F107Z6R3	1210 Y5V	100 µF, −20/+80%, 6.3 Vdc	no matching row	Mismatch — the largest capacitance code among the 109, undocumented
TT21F335Z100	TT low profile, Y5V	3.3 µF, −20/+80%, 10 Vdc	no matching row	Mismatch — all 56 TT export parts are X5R or X7R
1206F474Z500	1206 Y5V	470 nF, −20/+80%, 50 Vdc	row present, General Purpose Caps	Match on all fields — one of only 2 Y5V rows in 24,025
TT21X225K250	TT low profile, X5R	2.2 µF, ±10%, 25 Vdc	row present, Low Profile Caps	Match — shows the TT export is populated, just not with Y5V

Y5V is a Class II dielectric with a wide capacitance tolerance and a steep temperature characteristic, and it is the shortest route to bulk capacitance in a small case. That is why a shelf carries it and a specification-grade export may not. If your BOM has a Y5V position, the cross-reference tool will not see it — send it to us as a question rather than paste it into a form.

How many are near misses rather than real gaps?

30 of the 36 non-Y5V codes have a near neighbour in the export. We defined one precisely so you can repeat it: an export part number sharing the first eight characters — case size, dielectric and capacitance code — differing only in the tolerance letter and the three-digit voltage code. 30 of 36 have one. Only 6 have nothing within those eight characters.

Code we hold	Walsin export	Nearest export row	Match / mismatch
RF15N9R6B500	no matching row	RF15N9R6B250 and RF15N9R6A500 both present	Mismatch — the 9.6 pF value exists; this tolerance-and-voltage pair does not
S252B471K502ZT	no matching row	S252B471K502 present, 2211 X7R 470 pF	Mismatch — stock code adds ZT for soft termination and reel; strip it and it resolves
1808N391J102	no matching row	1808N391J202 present at 2,000 Vdc	Mismatch — same 390 pF NP0 part, different voltage code
1812N390J631	no matching row	1812N391J101 present	Mismatch — 39 pF at 630 Vdc absent, 390 pF at 100 Vdc present
0603B204K160	no matching row	nothing shares the first eight characters	Mismatch — no comparable 0603 X7R 2.0 µF row at all
0402N5R9C500	no matching row	nothing shares the first eight characters	Mismatch — 5.9 pF NP0 at 0402 is absent; 5.6 pF and 5.0 pF are present
WR12X0000FTL	no matching row	WR12X000PTL present	Mismatch — a 1206 zero-ohm jumper; the code differs by one character and a digit count

So the honest shape of the 109 is three groups: 73 where a whole dielectric is unpublished, 30 where the part family is published and this exact tolerance-and-voltage combination is not, and 6 where nothing comparable appears. Only the third group is genuinely unexplained.

Why did we publish 101 and now say 109?

Because the first count used the wrong reference set, and we would rather correct it than leave it standing. On 6 October 2026 we counted the unmatched codes against MASTER_PART_NUMBERS.txt, our 360,078-line index. That index is built from the exports and from the stock file itself, so 8 codes matched their own row in the stock register rather than any Walsin row: 08052R152K501BA, 1210F476Z10, S252B471K502ZT, SR471K05DOJNCEDEN, WF06Q7502FTL, WF06U5363BTL, WF08R1203BTL and WR12X0000FTL. None has a matching row in any export. The real figure is 109.

The only reason you are reading that is that we went back and measured the same thing a different way. A number nobody re-measures is a number nobody should quote. A distributor who never corrects anything is a distributor who never checks.

What should a Hong Kong buyer do when a part number is not found?

Send it to a person, not a form. 109 of 1,125 is a one-in-ten chance that a code on our own shelf will not resolve through the automated path, and the figure will be higher for your incumbent part from another maker. Hong Kong buyers have the advantage here: our counter is at Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., and the phone is (852) 2628 4777.

1. Cross everything that will cross. Paste up to 500 part numbers or drop an Excel or CSV into the free cross-reference tool. It is matched against Walsin’s published catalogue and states every difference from your original rather than hiding it, with filters for soft termination, high temperature, safety certified, high Q and low profile.
2. Send the residue as a question. Anything Y5V, anything with a packaging or termination suffix, and anything the tool returns as not found. We hold 28 Walsin datasheets, 451 pages, and will send the one covering your part number — and tell you plainly when we hold none, which is the case for 84.2% of our 359,135 part numbers.
3. Check the dated shelf separately on ready stock, as at 23 September 2026. Part-number counts only; stock is a snapshot and never a standing quantity.

For why these codes resist pasting at all, see why Walsin part numbers do not paste into your BOM. For the suffix that turns a catalogue key into an order code, see the Walsin CT suffix and orderable part numbers. For what the 203 files can and cannot answer, see what Walsin’s 203 export files can and cannot answer. The range is on the Walsin MLCC page.

The short version

109 of the 1,125 catalogue codes on our 23 September 2026 Hong Kong snapshot return no row in any of Walsin’s 203 parametric export files, searched cell by cell. 92 are size-prefixed chip MLCC codes, led by 0805 at 22; 12 are series-prefixed MLCC and 5 are chip resistor codes. 73 of the 109 are Y5V, against exactly 2 Y5V rows in the 24,025-row MLCC export. 30 of the 36 non-Y5V codes have a near neighbour differing only in tolerance and voltage code; 6 have nothing comparable. We published 101 and the correct figure is 109, because the first count was taken against an index that included our own stock file. We will not tell you a part is equivalent. We will show you where it differs — and when our own data cannot describe a part, we will tell you that too. Qualification stays with you.

Send us the lines a cross-reference tool returned as not found — ours or anyone’s — and we will decode the code by hand, say what we hold and what we do not, and tell you whether it was on the Hong Kong shelf on 23 September 2026. And if you think a Y5V position should be crossable automatically, tell us: 73 codes say the data is not there yet, and your question is what gets it asked.

---

Frequently asked questions

<!– wp:rank-math/faq-block {"questions":[{"id":"faq-question-01","title":"What does it mean when a Walsin part number is not found?","content":"It means no row in Walsin's published parametric data describes that code. We searched all 203 export files cell by cell, across 359,136 distinct part numbers, and 109 of our 1,125 Hong Kong catalogue codes returned nothing. It is a documentation gap, not a supply statement, and we do not read it as either.","visible":true},{"id":"faq-question-02","title":"Which product lines do the 109 unmatched codes belong to?","content":"92 are size-prefixed chip MLCC codes, spread across 0201 to 2220 with 0805 the largest group at 22. 12 are series-prefixed MLCC — 5 microwave RF, 3 soft termination SH, 2 low profile TT, 1 high Q HH and 1 safety S2. The remaining 5 are thin film, general purpose and array chip resistor codes.”,”visible”:true},{“id”:”faq-question-03″,”title”:”Why are so many of them Y5V?”,”content”:”Because the export barely carries that dielectric. We counted exactly 2 Y5V rows among the 24,025 real rows in the combined MLCC export, both 470 nF at 1206 and 50 Vdc. 73 of the 109 unmatched codes carry the F dielectric letter. The dielectric exists in the range; it is close to absent from the published data.”,”visible”:true},{“id”:”faq-question-04″,”title”:”Can Venatech still supply a code that is not in the export?”,”content”:”Being absent from a parametric file says nothing about availability. It means the automated cross-reference path cannot describe the part, so the question has to come to a person. Send the code and we will decode it by hand, tell you what documentation we hold, and tell you when we hold none.”,”visible”:true},{“id”:”faq-question-05″,”title”:”Why does the figure differ from the 101 you published earlier?”,”content”:”The first count was taken against our own 360,078-line master index, which is built from the exports and from the stock file together, so 8 codes matched their own stock row rather than a Walsin row. Re-measured against the export files alone, the figure is 109. We publish the correction rather than leaving the old number standing.”,”visible”:true},{“id”:”faq-question-06″,”title”:”Does a missing export row mean there is no datasheet either?”,”content”:”Usually, but not always. We hold 28 Walsin datasheets covering 451 pages, and 84.2% of our 359,135 part numbers have no datasheet at all — thin film, inductor, disc, RF, MOV and antenna lines have none. The safety code in this group is the exception: its series approval sheet is on file even though that exact stock code has no matching row.”,”visible”:true},{“id”:”faq-question-07″,”title”:”What is the fastest way to get an answer on an unmatched code?”,”content”:”Cross the rest of the list in one pass through the free cross-reference tool, then send the residue to us directly. We will decode the prefix, name the series it belongs to, state what we hold and what we do not, and tell you whether it appeared on the dated Hong Kong snapshot. The counter and the phone number are published.”,”visible”:true}],”listStyle”:””,”titleWrapper”:”h3″,”titleCssClasses”:””,”contentCssClasses”:””,”sizeSlug”:””} –>

---