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The Seven Fields You Need Before Anyone Can Cross Your Chip Resistor

A chip resistor cross reference needs seven fields: case size, resistance, tolerance,
temperature coefficient, rated power, packaging and termination. A ceramic capacitor cross
needs five. The two extra fields — rated power and TCR — are where a resistor cross is won or
lost, because two parts can share size, value and tolerance and still be rated differently.

Venatech Limited, an authorised Walsin Technology (Walsin) distributor in Hong Kong, holds an
extract of 234,815 Walsin chip resistor part numbers across 137 files. Every figure below comes
from it. Walsin’s own cross-reference search covers two product types, MLCC and CHIP-R, so a
chip resistor cross is a first-class path on the manufacturer’s tool as well as on ours.


What do I need in front of me before I can cross a chip resistor?

Seven fields off the incumbent datasheet: case size, resistance, resistance tolerance,
temperature coefficient of resistance, rated power at the reference temperature, packaging, and
termination finish. Add the working voltage limit if the resistor sits near it, and any
anti-sulfuration or automotive requirement.

Three of the seven are routinely skipped. TCR, because most general-purpose parts are
±100 ppm/°C and it feels like a default. Rated power, because engineers read the case size as if
it fixed the rating, which it does not. Termination finish, until the assembly house asks.

Write the resistance in ohms, unconverted. Walsin’s parametric export states resistance as a
plain ohm figure — a 10 kΩ part is 10000Ω in the data, not 10K.

How is a chip resistor cross different from an MLCC cross?

Two more fields, and both of them are electrical limits rather than nominal values. On an
MLCC, the five headline fields are size, dielectric, capacitance, tolerance and rated voltage.
On a chip resistor, rated power and TCR sit alongside size, resistance and tolerance, and
neither can be inferred from the others.

Rated power is the sharper of the two. In Walsin’s extract, the same case size carries several
different ratings depending on the series. Across Walsin’s extract, parts labelled 0603 (1608)
appear at six different rated powers: 1/16 W, 1/10 W, 1/8 W, 1/4 W, 1/3 W and 1/2 W. Reading a
rating off a case code is the single most common chip resistor error, and
chip resistor power rating by case size sets
out what the code does and does not fix.

TCR matters in a different way. A divider that sets a reference, a current-sense shunt or a
bridge leg moves with temperature at whatever the TCR allows. Walsin publishes discrete TCR
classes — ≦±25, ≦±50, ≦±100, ≦±200, ≦±300 ppm/°C and several asymmetric bands — and a cross
that moves you from ≦±50 to ≦±200 has changed your circuit.

How many Walsin parts match one 0603 10k ohm 1% line?

Thirteen. Take a 0603 (1608) 10 kΩ ±1% 1/10 W ≦±100 ppm/°C line and Walsin’s published
catalogue returns thirteen part numbers across nine series. All thirteen match on case size,
resistance, tolerance, TCR class, rated power, packaging and termination. They differ on grade
and construction.

Walsin part number Series Match / mismatch against a 0603 10 kΩ ±1% 1/10 W ≦±100 ppm/°C line
WR06X1002FTL Thick Film General Purpose Chip Resistor Match on all seven fields — baseline commercial part
WR06X1002FTR General Purpose, LF 100 ppm Match on seven fields — mismatch: different TCR construction within the same class
WR06X1002FTLJ General Purpose (Automotive) Match on seven fields — mismatch: automotive grade, not a commercial part
WR06X1002FTLV General Purpose Anti-Sulfuration (Automotive) Match on seven fields — mismatch: anti-sulfuration and automotive
WR06X1002FTLZ General Purpose Anti-Sulfuration (Automotive) Match on seven fields — mismatch: anti-sulfuration and automotive
MR06X1002FTR General Purpose LF 100 ppm (Automotive) Match on seven fields — mismatch: automotive series prefix MR
MR06X1002FTLV General Purpose (Automotive) Match on seven fields — mismatch: automotive series prefix MR
SR06X1002FTL High Grade Anti-Sulfuration (Automotive) Match on seven fields — mismatch: high-grade anti-sulfuration construction
SR06X1002FTLW High Grade Anti-Sulfuration (Automotive) Match on seven fields — mismatch: high-grade anti-sulfuration construction
WK06V1002FTL Thick Film High Voltage Match on seven fields — mismatch: high-voltage series, different working voltage limit
WK06V1002FTLJ Thick Film High Voltage (Automotive) Match on seven fields — mismatch: high-voltage and automotive
WF06V1002FTL Thick Film High Voltage Match on seven fields — mismatch: high-voltage series, different prefix
WA06X1002FTL Chip Resistor Array, 0603×4, Convex type Mismatch — this is a four-element array, not a discrete 0603 chip

All thirteen are listed with 7-inch reel taping and an Sn-base lead-free termination, from the
Walsin thick film chip resistor datasheets.

The last row is the one to notice. Twelve of the thirteen are discrete chips; the thirteenth is
a resistor array, and it arrived because of how the size field is written.

Why does a size filter return array parts alongside discrete chips?

Because on array parts the Size field describes the element, not the package. Walsin’s
extract lists WA06X1002FTL with a size of 0603(1608) and a series of “Chip Resistor Array
0603×4, Convex type”. The size is the size of each of the four resistors inside, not the
footprint you would lay down.

Unique to Venatech’s data. 42,374 rows in Walsin’s chip resistor export carry a Size
field reading 0603(1608). 5,076 of them are array parts whose series name states an element
count — 0603×2, 0603×4 or 0602×8. A cross or a filter that works on the size field alone
will return arrays alongside discrete chips, and the two are not interchangeable on a board.
The series name is the field that separates them.

This is not an error in the data. It is a labelling convention that makes sense from the
manufacturer’s side, where an array is specified by its element. If the result names a series
with a multiplier in it, you are looking at an array.
Chip resistor arrays explained covers convex, concave
and the pinout differences.

Which Walsin chip resistor part numbers will not paste cleanly?

39,576 of them contain an embedded space. That is 16.9% of the 234,815-row extract, covering
39,162 distinct part numbers, and it matters because a space breaks a paste into a BOM column,
a search box or a cross-reference field. Not one of Walsin’s 24,026 MLCC part numbers has this
property.

Pattern Rows Example, verbatim from the extract Match / mismatch on a paste
Stem + space + 3 characters 26,114 WF04A000 PTL Mismatch — splits into two tokens
Stem + space + 4 characters 12,466 WK25S1R0 KTLJ Mismatch — splits into two tokens
Full code + space + 2 characters 921 WR20F1R00FTL HN Mismatch — trailing token looks like a note
Two separate spaces 75 WR12F1R0 JTL FN Mismatch — splits into three tokens
No space 195,239 WR06X1002FTL Match — pastes as one token

Unique to Venatech’s data. Two Walsin chip resistor series groups are 100% affected. Every
one of the 2,940 Trimmable Chip Resistor part numbers carries an embedded space, and so does
every one of the 98 Chip Resistor Network, Convex Type part numbers. If you are crossing into
either of those families, expect to normalise every line.

Strip the space and the code is fine; the failure is silent, which is the problem.
Why Walsin part numbers do not paste into your BOM
sets out the normalisation step.

Which rated powers does a public filter dropdown not offer?

Two: 1.5 W and 1/5 W. Both are real, orderable Walsin ratings with parts behind them, and
neither appears in the rated-power dropdown on Walsin’s public parametric search. A cross built
by driving that dropdown will therefore never reach them. Venatech’s extract holds 3,615 parts
between the two.

Rated power Parts in Venatech’s extract Case size Series groups Match / mismatch against a dropdown-driven search
1.5 W 1,950 2010 (5025) only Thick Film High Power Mismatch — rating not offered in the public filter
1/5 W 1,665 0402 (1005) only High Power, Anti-Surge Mismatch — rating not offered in the public filter
1 W 24,569 seven case sizes, 2512 to 0815 several Match — a rating the filter reaches normally

Unique to Venatech’s data. Each of the two ratings sits in exactly one case size. All
1,950 of the 1.5 W parts are 2010 (5025). All 1,665 of the 1/5 W parts are 0402 (1005), split
between the High Power and Anti-Surge series groups. If a cross needs 1.5 W it needs a 2010,
and 1/5 W in an 0402 does exist — ask for it by specification.

Where do I enter a chip resistor cross, and what comes back?

Two routes, both valid, with different endpoints. Walsin’s own cross-reference search takes
CHIP-R as a product type, asks you to name the vendor from its list, accepts comma-separated
part numbers or an uploaded Excel file, and returns the identification. VenaMatch offers “Chip
resistor” at its category step and carries the answer into a quantity and an RFQ line.

That is a division of labour. Walsin does not sell direct, so naming a compatible Walsin part is
the whole of what the manufacturer can responsibly do. Venatech is the authorised distributor,
so the answer can continue into a quantity, a price break and a person. Walsin’s tool does the
engineering half; we do the commercial half.
Why a manufacturer’s cross tool ends where your decision begins
covers the handover.

Is the crossed resistor approved for my board?

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. Neither Walsin nor Venatech
can assess how a resistor behaves in your circuit, and on a resistor the behaviour that matters
is often thermal.

Walsin’s cross-reference preamble puts it plainly: you must evaluate the suggested replacement
and conduct necessary tests before proceeding with mass production. VenaMatch prints the same
position on every result. Two tools, one standard.

For a resistor, the evaluation list is short. Measure the temperature rise at worst-case
dissipation, not at nominal. Confirm the working voltage limit against the actual node, not the
rail. Check pulse handling if the part sees inrush or ESD. Confirm the termination finish
against your solder process before the first build.


FAQ

What do I need to cross-reference a chip resistor?

Seven fields from the incumbent datasheet: case size, resistance, resistance tolerance, temperature coefficient, rated power, packaging and termination finish. Add the working voltage limit and any automotive or anti-sulfuration requirement. Rated power and TCR are the two that cannot be inferred from the others, and they are the two most often omitted.

How many Walsin parts can match one chip resistor specification?

More than one, routinely. A 0603 10 kΩ ±1% 1/10 W ≦±100 ppm/°C line returns thirteen Walsin part numbers across nine series in Venatech’s extract, all matching on the seven headline fields. They differ on grade and construction: commercial, automotive, anti-sulfuration, high-voltage, and in one case a four-element array.

Does a 0603 chip resistor always have the same power rating?

No. Case size does not fix rated power. In Walsin’s extract, parts labelled 0603 (1608) appear at six rated powers: 1/16 W, 1/10 W, 1/8 W, 1/4 W, 1/3 W and 1/2 W. Read the rating off the datasheet for the specific series, and confirm the derating curve above the reference temperature before committing to a cross.

Why does my chip resistor part number break when pasted into a BOM?

Because 39,576 rows in Walsin’s chip resistor export contain an embedded space inside the part number, covering 39,162 distinct codes. A space splits the value across two spreadsheet cells or two search tokens. Strip the space and the code is correct. None of Walsin’s 24,026 MLCC part numbers has this property.

Which Walsin chip resistor ratings are not in the public filter?

1.5 W and 1/5 W. Both are real, orderable ratings. Venatech’s extract holds 1,950 parts at 1.5 W, all in 2010 (5025), and 1,665 at 1/5 W, all in 0402 (1005). Neither rating appears in the public rated-power dropdown, so ask for them by specification instead.

How do I tell a resistor array from a discrete chip in a cross result?

Read the series name, not the size field. On array parts the size describes the element, so an array shows 0603(1608) while its series reads “0603×4”. 5,076 of the 42,374 rows labelled 0603(1608) in Walsin’s export are array parts. An array and a discrete chip are not interchangeable on a board.

Does Walsin’s own cross-reference tool cover chip resistors?

Yes. Its product type selection covers two lines, MLCC and CHIP-R, so a chip resistor cross is a first-class path on the manufacturer’s tool. It asks you to name the vendor from its own list, accepts comma-separated part numbers or an uploaded Excel file, and returns the identification of a suggested Walsin part.

Is a crossed chip resistor an approved substitution?

No. It is a specification match against Walsin’s published catalogue, offered as a candidate for evaluation. Walsin’s tool asks users to evaluate the suggested replacement and run the necessary tests before mass production. Measure temperature rise at worst-case dissipation, confirm the working voltage at the actual node, and qualify in your application.


Next step

Send the seven fields, not the part number. Give Venatech Limited, an authorised Walsin
distributor in Hong Kong, the case size, resistance, tolerance, TCR, rated power, packaging and
termination, and you get back the Walsin candidates, every field that matches, every field that
does not, and the orderable code.

Send your resistor lines to Venatech · Browse the
Walsin chip resistor range · Read
Chip resistor power rating by case size and
Why Walsin part numbers do not paste into your BOM.


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.

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