EOL component replacement starts with the specification, not the part number. Read the
last-time-buy date, write down every field from the datasheet, then count how many candidate
parts that specification returns — it is rarely one. Check thickness and dimensional
tolerance, get the orderable packaging code, then qualify the candidate in your own circuit
before production.
This post is about what a buyer does when a notice arrives. It makes no claim about any
manufacturer’s product status. Venatech Limited, an authorised Walsin Technology (Walsin)
distributor in Hong Kong, holds no other manufacturer’s affected-part list, and anything you
have been told about a specific part number should be confirmed with that manufacturer or
their distributor in writing.
What should I do first when an EOL notice lands?
Extract the four dates before anything else: the notice date, the last-time-buy date, the
last-ship date, and any deadline for submitting a final order. Those set your runway.
Everything else in this checklist is engineering work, and engineering work expands to fill
whatever time you leave it.
Then count what you still need. Annual usage times remaining product life, plus a service
tail, gives the last-time-buy quantity. If that number fits inside the last-time-buy window
and inside your storage and cash constraints, a bridge buy buys you time to do the
replacement properly rather than under deadline. If it does not, the replacement is the
project and the dates are the schedule.
Record the affected part numbers exactly as the notice writes them, including any packaging
suffix. A notice that names a bulk-packed code and a notice that names a reel-packed code
are different lines on your BOM even when the die inside is identical.
Why does the replacement search start from the specification, not the part number?
Because a part number is one vendor’s index into their own catalogue, and no other vendor
shares that index. The specification is the thing that is portable. Open the datasheet for
the line you have been asked to replace and write down case size, dielectric, capacitance or
resistance, tolerance, rated voltage, and the qualification the design depends on.
Six fields is the minimum for a ceramic capacitor. Add termination style, thickness and
packaging. For a resistor, add rated power and temperature coefficient. Anything left off the
sheet is a field you will guess at later.
Write the numbers in the datasheet’s own units before converting anything. A 100 nF part, a
0.1 µF part and a 104 code are the same value, but a spreadsheet filter does not know that.
How many candidate parts does one specification actually return?
More than one, almost always. Take a 1206 X7R 1000 pF ±10% 2000 Vdc line. Walsin’s published
catalogue, as held in Venatech’s extract of 24,026 Walsin MLCC part numbers, returns eight
rows against those five fields — three distinct Walsin part numbers, published at four
different thicknesses.
| Walsin part number | Series | Published thickness (mm) | Match / mismatch against a 1206 X7R 1000 pF ±10% 2000 V line |
|---|---|---|---|
1206B102K202 |
Middle to High Voltage (200 V–4 kV) | 0.80±0.10 | Five headline fields match — thinnest of the four published options |
1206B102K202 |
Middle to High Voltage (200 V–4 kV) | 0.95±0.10 | Five fields match — mismatch on thickness against the row above |
1206B102K202 |
Middle to High Voltage (200 V–4 kV) | 1.25±0.10 | Five fields match — mismatch on thickness |
1206B102K202 |
Middle to High Voltage (200 V–4 kV) | 1.60±0.20 | Five fields match — 1.80 mm worst case, more than twice the thinnest row |
1206B102K202 |
Middle to High Voltage (200 V–4 kV) | not stated | Five fields match — mismatch: no thickness published on this row |
SG31B102K202 |
Soft Termination SG, Cu-poly | 1.25±0.10 | Five fields match — mismatch: Cu-poly soft termination, and length is 3.20+0.40/−0.10 |
SH31B102K202 |
Soft Termination SH, Ag-poly | 1.25±0.10 | Five fields match — mismatch: Ag-poly soft termination |
SH31B102K202 |
Soft Termination SH, Ag-poly | 1.60±0.20 | Five fields match — mismatch: termination and thickness both differ |
Sources: Walsin MLCC Middle and High Voltage,
Soft Termination SG
and Soft Termination SH.
The five headline fields match on every row. That is the point. A cross that stops at those five
fields has done its job honestly and still left you a choice, and the choice is thickness and
termination. One Specification, 13 Walsin Parts works
the same arithmetic on a general-purpose 0603 line.
Which two fields do I have to check by hand?
Thickness and tolerance. Walsin’s own cross-reference search tells its users exactly this: its
step 4 reads “Double check the thickness and tolerance of the suggested part to ensure
accuracy.” That is a manufacturer being straight with the people using its tool, and it is the
best single sentence written anywhere about why a cross needs a human afterwards.
Thickness is the field a headline specification never carries. A case code fixes length and
width and says nothing about height. In the eight rows above, the same part number appears at
0.80 mm and at 1.60 mm nominal. A shield can, a stacked board, a conformal coat window or a
wave-solder rule will care about that difference, and the part number will not warn you.
Tolerance needs the same care because the word covers two different things. Capacitance
tolerance is the electrical band. Dimensional tolerance is the mechanical band on length,
width and thickness, and it is quoted separately per series. A part at 1.60±0.20 mm reaches
1.80 mm at worst case; a part at 0.80±0.10 mm tops out at 0.90 mm.
What is the orderable part number, and why is it not the catalogue code?
The catalogue code identifies the part. The orderable code adds packaging. On Walsin MLCC,
that is usually a trailing CT, and the parametric export does not include it — so a code
copied out of a search result is not a code you can raise a purchase order against.
Unique to Venatech’s data. In Venatech’s own stock snapshot of 1,125 part numbers, dated
23 September 2026, 865 order codes differ from the catalogue code for the same part. In every
one of the 865 the difference is exactly a trailingCT. That is 77% of the snapshot where
the code you would search with is not the code you would order with.
Ask for the orderable code in writing as part of the replacement package, alongside the
standard packing quantity. The CT suffix explained
covers the encoding. A related trap is whitespace: some Walsin chip resistor codes carry an
embedded space and will not paste cleanly into a BOM, which
Why Walsin part numbers do not paste into your BOM
sets out in full.
Can I get the candidate now, or does it have to be built?
Ask before you qualify, not after. Qualification work on a candidate that carries a long build
lead time is work you may have to repeat. A candidate that is already sitting in Hong Kong
gives you samples this week and a bridge while the replacement is approved.
Of the 1,125 part numbers in that 23 September 2026 snapshot, 949 appear in Venatech’s
extracts of Walsin’s published catalogue; the remainder are other authorised lines. Counts are
part numbers, not pieces, and a snapshot moves — treat it as a starting point for an enquiry,
never as a guarantee. How to check Walsin stock and reserve it
covers the mechanics.
Two practical asks at this stage. First, request samples from the same date code you would
later buy in volume. Second, ask what buffer arrangement is possible on the candidate, because
a replacement that survives one build and then goes short has not solved anything.
Is a crossed part an approved replacement?
No. A cross result is a specification match against a published catalogue, offered as a
candidate for your evaluation. It is not an approved substitution, and no distributor and no
manufacturer can assess how a part behaves in your circuit. Check the datasheet, then qualify
the candidate in your application.
Venatech’s cross-reference tool, VenaMatch, carries that wording on every result. Walsin’s own
cross-reference preamble says the same thing in its own words: you must evaluate the suggested
replacement and conduct necessary tests before proceeding with mass production. Two independent
tools, one position, and it is the correct one.
What qualification looks like depends on what the part does. A decoupling capacitor in a
digital rail and a snubber across a switching node are different risk cases even at the same
specification. Write the test plan against the function, not against the part number.
What does the finished checklist look like?
Eleven lines, in order, and none of them optional. Dates and quantities first, specification
second, candidates third, the two hand-checked fields fourth, commercial detail fifth, and
qualification last. Nothing here is fast, but every step you skip reappears later as a
production hold.
| # | Step | What good looks like |
|---|---|---|
| 1 | Record the four dates | Notice, last-time-buy, last-ship, order deadline |
| 2 | Size the bridge buy | Annual usage × remaining life + service tail |
| 3 | Rebuild the specification from the datasheet | Case size, dielectric, value, tolerance, voltage, plus power and TCR on resistors |
| 4 | Record termination, thickness and packaging | Three fields a headline specification omits |
| 5 | Cross the specification, not the part number | Expect several candidates, not one |
| 6 | Check thickness worst case | Nominal plus the positive dimensional tolerance |
| 7 | Check both meanings of tolerance | Electrical band and dimensional band, separately |
| 8 | Confirm the qualification you actually need | AEC-Q200 or not, soft termination or not |
| 9 | Get the orderable code and the packing quantity | Catalogue code plus packaging suffix, in writing |
| 10 | Ask what is available now and what is built | Samples from a real date code; buffer arrangement agreed |
| 11 | Qualify in your own application | A candidate becomes a replacement only here |
Keep the sheet. The next notice will ask the same eleven questions about a different line, and
a filled-in sheet from last time is the fastest engineering document you own.
FAQ
What does EOL mean on a component?
End of life. It means the manufacturer has announced that it will stop building and shipping a product, and it normally comes with a last-time-buy date and a last-ship date. It is an announcement about a product line, not a statement that existing stock has become unusable.
How do I find a replacement for an end-of-life capacitor?
Work from the specification, not the part number. Take case size, dielectric, capacitance, tolerance, rated voltage, termination and thickness off the datasheet, then cross that set against another manufacturer’s published catalogue. Expect several candidates. Narrow them on qualification grade, termination and thickness, then qualify in your own circuit.
How much should I buy on a last-time-buy?
Annual usage multiplied by the remaining production life of the product, plus a service and warranty tail, plus scrap allowance. Compare that against the last-time-buy window, your storage conditions and your cash position. If the bridge buy fits, it converts a deadline into a planned replacement project instead of an emergency.
Does a cross-reference tool give me an approved replacement part?
No. It gives a specification match against a published catalogue, offered as a candidate for evaluation. Walsin’s own cross-reference tool asks users to evaluate the suggested replacement and run the necessary tests before mass production. VenaMatch carries the same standing disclaimer on every result it returns.
Why does the part number on my quote differ from the catalogue?
Because the catalogue code identifies the part and the order code adds packaging. On Walsin MLCC that is usually a trailing CT, which the parametric export omits. In Venatech’s stock snapshot of 1,125 part numbers dated 23 September 2026, 865 order codes differ from the catalogue code by exactly that suffix.
Which fields does a case size not tell me?
Thickness, termination style, and qualification grade. A 1206 code fixes nominal length and width. It leaves height open, and Walsin publishes some 1206 part numbers at more than one thickness. It says nothing about whether the part is standard-terminated or soft-terminated, or whether it is AEC-Q200 qualified.
Can Venatech tell me whether a specific competitor part is discontinued?
No. Venatech holds no other manufacturer’s affected-part list and will not assert a status it cannot verify. Confirm any end-of-life claim with that manufacturer or their authorised distributor in writing. What Venatech can do is take the specification and return Walsin candidates with every matching and non-matching field stated.
How long should an EOL replacement take?
Longer than the notice window usually allows, which is why the bridge buy matters. The engineering path is specification, candidate list, thickness and tolerance check, samples, qualification, then a production release. Start the specification sheet on the day the notice arrives, not on the day the last-time-buy deadline is reached.
Next step
Send the specification, not the part number. Give Venatech Limited, an authorised Walsin
distributor in Hong Kong, the case size, dielectric or composition, value, tolerance, voltage
and any qualification requirement, and you get back the Walsin candidates, every field that
matches, every field that does not, the orderable code with its packaging suffix, and what is
available against the current snapshot.
Send the affected BOM lines to Venatech · Browse the
Walsin MLCC range · Read
One Specification, 13 Walsin Parts and
The CT suffix: orderable Walsin part numbers.
Cross it yourself. The cross-reference tool takes a single part number or a whole BOM column and returns the Walsin candidates with every field that differs stated plainly — qualification stays with you. Ready stock shows what is held in Hong Kong today, with an RFQ against any line.