Your Supplier Quoted a 40-Week Lead Time: A 5-Step Plan for Passives, and a 0603 100 nF Search That Grows From 4 Parts to 31, With 16 of the 31 Taller

A 40-week lead time on a passive is a search problem before it is a supply problem. Freeze the specification, count the candidates strictly and then in the safe direction, triage the mismatches, check a dated shelf, and qualify two candidates in parallel. We ran the plan on a 0603 X7R 100 nF capacitor and a 0603 10 kΩ resistor.

Venatech Limited, an authorised Walsin distributor in Hong Kong, wrote this plan from two exports and one stock file: Walsin Technology (Walsin) 00_ALL_MLCC_parts_combined.xlsx (24,026 rows), the 137 chip resistor files (234,815 rows), and our Hong Kong stock snapshot dated 23 September 2026. We make no claim about anyone’s lead time, and we name nobody as short. Every part number below is real, and we re-counted every figure.

What do you do first when a supplier quotes 40 weeks on a passive?

Write the specification off the datasheet and stop reading the part number. A capacitor needs six fields: case size, dielectric, capacitance, tolerance, rated voltage and maximum height. A chip resistor needs five: case size, resistance, tolerance, rated power and temperature coefficient. Our two worked lines have 6 and 5 fields, and each field is a filter that removes parts.

Add the one field nobody writes down: grade. If the line sits in a vehicle or a safety path, say so now, because grade removes candidates faster than any electrical field. Our test lines are a 0603 X7R 100 nF ±10% 16 V capacitor with a 0.87 mm height ceiling, and a 0603 10 kΩ ±1% 1/10 W resistor with a temperature coefficient of 100 ppm per degree Celsius or better. They are generic specifications, not any maker’s part. We read the ordering key in Walsin’s General Purpose approval sheet (01_General_Purpose.pdf, 21 pages, September 2026) to confirm the fields: in 0603B104K160, B is X7R, 104 is 100 nF, K is ±10% and 160 is 16 V. The cross-reference tool takes your incumbent part number and reads those fields for you across 18 manufacturers’ part numbers decoded, so the first step is minutes of work, not a day.

How many parts does a strict search return, and what does relaxing it add?

Strictly, 4 capacitors and 15 resistors. Relaxed only in the safe direction (voltage up, tolerance tighter, power up, TCR tighter), they become 31 and 45. We parsed all 24,026 MLCC rows and all 234,815 chip resistor rows, and the lists grow by 27 and 30 part numbers once we allow the safe direction. The catch is that the safe direction moves fields you did not ask about.

We have not seen this counted anywhere: 16 of the 31 capacitors are taller than the 0.87 mm the strict part allows. The 50 V and 100 V general-purpose parts publish a thickness of 0.80 +0.15/−0.10 mm, a worst case of 0.95 mm, and the soft-termination parts at 50 V and 100 V publish 0.80 ±0.30 mm, a worst case of 1.10 mm. Going up in voltage to find more stock quietly changes the height. Capping height at 0.87 mm leaves 15.

There is a second trap in the strict count. A column filter for “±10%” finds 3 capacitors, not 4. The fourth, MG18B104K160, is hidden because the export’s Tolerance column holds -0.1 on 656 of the 788 MG-series rows, a defect we published earlier and reproduce here on a live search. The K in the part number is what tells you it is ±10%.

Which candidates cross to Walsin and which do not?

Of the strict capacitor list, three parts match on every field and one differs in termination. Of the resistor list, the general-purpose parts match, and the arrays, the high-voltage series and the higher-power series each differ in a field you must read. The column to read is the last one, because it states what differs rather than calling anything an alternative. Leave the incumbent column for your own part.

Six of the 21 resistors that pass the first four fields are arrays. A search that stops at case size, value, tolerance and power returns them, and an array on a single-resistor footprint will not place. Our post on one specification, 13 Walsin parts shows the same effect on a general-purpose capacitor line, and how to cross-reference an MLCC covers the field order.

Which candidates were on the Hong Kong shelf on 23 September 2026?

Five of the 31 capacitors and one of the 45 resistors. We joined both lists to our stock snapshot of 1,125 part numbers, dated 23 September 2026, and we checked every match by catalogue code. The capacitors on the shelf were 0603B104K101, 0603B104K160, 0603B104K250, 0603B104K500 and SH18B104K500; the one resistor was WR06X1002FTL. Inside the 0.87 mm height ceiling, two capacitors remain: 0603B104K160 and 0603B104K250.

A snapshot is not a promise, and quantities move. The shelf proves a candidate exists in Hong Kong today, so you can order samples while the 40 weeks runs. Check Hong Kong ready stock for the current view and send the part for a dated answer. The orderable capacitor code carries a packaging suffix: 0603B104K160CT is what goes on the order, and the CT suffix post explains why. The resistor code WR06X1002FTL is identical in both columns.

The resistor shelf is thin on this value, and we will say so. Across the 95 ten-kilohm 0603 resistors, one is held. The same shelf holds a deep general-purpose resistor range, but a 10 kΩ ±1% part is one value of many. Ask for the value you need, not the family.

What do you run in parallel while the 40 weeks ticks down?

Two candidates, not one, and the original order position left alone. Qualify the closest match and the nearest safe-direction part side by side, and keep the existing order until one has passed in your own circuit. One candidate that fails restarts your clock; two candidates give you a fallback inside the same sample window.

The five steps, in order: (1) freeze the specification off the datasheet; (2) count strictly, then in the safe direction only; (3) triage the mismatches, starting with height, termination and grade; (4) intersect with a dated shelf; (5) order samples of two candidates and qualify both. A cross result is a specification match against a published catalogue, never an approval. For a whole BOM, the BOM checker takes up to 500 part numbers or an Excel or CSV file and states every difference.

Does Walsin’s export tell you a lead time?

No. We opened both exports, 00_ALL_MLCC_parts_combined.xlsx and the 137 chip resistor files, and counted the columns: the MLCC export has 16 and the chip resistor files have 10, and none of them is a lead time, a stock level or a status. Lead time is a fact you ask for, per part number, in writing. We do not publish one, and we make no claim about any maker’s.

That is why steps 1 to 4 matter. They turn “40 weeks” from a number you accept into a question you can put to a second source with a precise list attached. Confirm against both datasheets, and qualify in your own circuit.

The short version

Freeze six capacitor fields or five resistor fields. Strict search: 4 capacitors and 15 resistors. Safe direction: 31 and 45, but 16 of the 31 capacitors are taller than the strict part. A tolerance-column filter hides MG18B104K160. One of the 45 resistors and five of the 31 capacitors were on the Hong Kong shelf on 23 September 2026. Qualify two candidates in parallel and keep the original order.

Paste your incumbent into the free cross-reference tool, or send us the BOM lines behind the quote. We will return the Walsin candidates with every difference stated, and tell you which were on the shelf. Qualification stays with you. And a question: when your buyer last saw “40 weeks”, did anyone count the alternatives before accepting it?

Browse the Walsin MLCC range and the chip resistor range.

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