Passive component sourcing: MLCCs, capacitors, resistors, inductors and crystals
Chip capacitors, aluminium, polymer and tantalum capacitors, chip and precision resistors, inductors, ferrite beads, crystals and oscillators, by complete ordering code or by specification. We check case code, dielectric, voltage, tolerance and reel quantity on every line, and the ratings that decide whether a second source works in your circuit.
- Active, EOL and allocated parts; cut tape to full reels
- Case code, dielectric, voltage and tolerance checked against the datasheet
- Second sources listed with the ratings that differ
What we source
Six groups cover most passive lines on a BOM. Passives are bought as BOM lines, often hundreds at a time, so each line has to be read for the few numbers that decide whether it works.
MLCCs
Multilayer ceramic capacitors from 0201 to 1210 and larger, in C0G, X7R and X5R. Typical lines: GRM188R61E106MA73, GRM155R71C104KA88, CL10B104KB8NNNC.
Aluminium electrolytic and polymer
SMD and radial aluminium capacitors for bulk, bus and input filtering. Typical lines: EEE-FK1E101XP, UWT1E101MCL1GS.
Tantalum
MnO2 and polymer tantalum chip capacitors for compact, stable bulk capacitance. Typical lines: T491A106K016AT, T491T106K016AT, T520D477M004ATE010.
Chip and precision resistors
Thick film, thin film and current-sense chip resistors. Typical lines: RC0603FR-0710KL, ERJ-3EKF1002V.
Induttori e perline di ferrite
Power inductors, RF inductors and ferrite beads for converters and EMI filtering. Typical lines: BLM18PG121SN1D, XAL5030-472ME, LQH32CN4R7M23L.
Cristalli e oscillatori
Quartz crystals, 32.768 kHz tuning-fork crystals and oscillators for MCU and RTC clocks. Typical lines: FC-135 32.768 kHz, ABM8-16.000MHZ-B2-T.
What a passives quote depends on
Send what you have. A complete ordering code is fastest; a value with its specification works too, and we come back with candidate codes.
- Complete ordering code, including case size, dielectric or series, voltage, tolerance and packing letters
- Quantity and target date, so we can compare distribution, independent stock and factory lead time
- Case code system: inch (0603) or metric (1608). "0603" names different parts in the two systems
- Qualification: AEC-Q200 or standard grade, and any temperature requirement
- Alternative rule: original only, discuss first, or your approved list
- For a requirement: value, tolerance, rated voltage or power, case size and dielectric or technology
The quote line states the source channel, packaging, date code, lead time and validity. Parts are supplied as packed by the manufacturer. Nothing is substituted without your written approval.
Representative parts and their key numbers
These are lines we see often. The numbers are the ones a replacement must match, taken from the manufacturers’ datasheets and product pages.
GRM188R61A106KE69D
MLCC, X5R
10 µF ±10%
10 V
Capacitance falls under DC bias
0603 (1608 metric)
GRM188R61E106MA73
MLCC, X5R
10 µF ±20%
25 V
Same value and case, higher voltage
0603 (1608 metric)
EEE-FK1E101XP
Aluminium electrolytic
100 µF
25 V
2,000 h at 105 °C
6.3 × 7.7 mm
T491A106K016AT
Tantalum, MnO2
10 µF ±10%
16 V
ESR 3 Ω; 1.8 mm high
3216 (1206)
T491T106K016AT
Tantalum, MnO2
10 µF ±10%
16 V
ESR 8 Ω; low profile, 1.2 mm
3528 (1411)
RC0603FR-0710KL
Thick film resistor
10 kΩ ±1%
0.1 W at 70 °C
TCR ±100 ppm/°C
0603 (1608 metric)
BLM18PG121SN1D
Perla di ferrite
120 Ω at 100 MHz
2 A
Rated for −55 to 125 °C
0603 (1608 metric)
XAL5030-472ME
Induttore di potenza
4.7 µH
Isat and Irms
Two separate current ratings
XAL5030 series
FC-135 (Q13FC13500005)
32.768 kHz crystal
12.5 pF load
±10 ppm
ESR 70 kΩ max; a 7.0 pF version exists
3.2 × 1.5 mm
Example parts, not a stock list. Confirm the current datasheet and the exact suffix before design or purchase. Need one of these? Send the part number and we confirm the orderable code and stock.
How to specify each group
Two passives with the same value and footprint can behave differently in your circuit. The difference is usually a derating curve, a current rating or a load condition that the value does not show.
Each tab lists what defines the part, the numbers to compare, the trap we see most often, and what to send so we can quote without guessing.
What defines the part. Case size, dielectric (C0G, X7R, X5R), rated voltage, capacitance, tolerance, thickness and packing.
Numbers to check. Capacitance at your working DC voltage, rated voltage, dielectric class, case code system, thickness.
Common trap. X5R and X7R lose capacitance as DC voltage rises; C0G does not. A 10 µF 10 V X5R GRM188R61A106KE69D on a 5 V rail does not give 10 µF, so read the DC bias curve for the exact part. Case codes also collide: 0603 in inch is 1608 metric, while a metric 0603 is a 0201 inch part. State which system your BOM uses.
Inviaci: Full MPN, the working voltage on the net, and the case code system.
What defines the part. Capacitance, rated voltage, case diameter and height, rated life at temperature, ripple current, ESR and temperature range.
Numbers to check. Rated life and its test temperature, ripple current, ESR, case dimensions, polarity mark.
Common trap. Rated life is given at the maximum temperature, and as a rule of thumb it doubles for each 10 °C lower. EEE-FK1E101XP is rated 2,000 h at 105 °C, so at 85 °C expect about 8,000 h; ripple current heats the part and shortens this. The same value and voltage also comes in more than one case size within a series, set by the suffix, so check diameter and height against the land pattern.
Inviaci: Full MPN, the ripple current and the highest ambient temperature at the capacitor.
What defines the part. Capacitance, rated voltage, case size, ESR, electrolyte (MnO2 or polymer) and tolerance.
Numbers to check. Rated voltage against working voltage, ESR, case height, surge conditions.
Common trap. MnO2 tantalum is usually derated by about 50% of rated voltage; polymer types need less. The same value also comes in different bodies: T491A106K016AT has 3 Ω ESR in a 1.8 mm 3216 case, and T491T106K016AT has 8 Ω in a 1.2 mm 3528 case. A swap between them changes the ESR by a factor of almost three.
Inviaci: Full MPN including the case letter, the working voltage and the source impedance.
What defines the part. Resistance, tolerance, TCR, power rating, case size and technology (thick film, thin film, current-sense).
Numbers to check. Power at ambient temperature, tolerance, TCR, working voltage, ordering-code letters.
Common trap. Tolerance is in the ordering code. RC0603FR-0710KL is ±1% with a TCR of ±100 ppm/°C and 0.1 W at 70 °C; above 70 °C the allowed power falls. A drawing that says “10 kΩ 0603” does not say which tolerance, TCR or technology was designed in.
Inviaci: Full MPN, the dissipated power in the circuit, and the tolerance and TCR you need.
What defines the part. Inductance, case size, Isat, Irms, DCR, shielding and, for beads, impedance at 100 MHz.
Numbers to check. Isat and Irms as separate ratings, DCR, inductance tolerance, bead current rating.
Common trap. Isat is the DC current at which inductance falls by a stated amount; Coilcraft lists it at 10%, 20% and 30% drop. Irms is the current for a stated temperature rise, 40 °C on the XAL50xx series. Makers use different drop percentages, so two “3 A” inductors may not be equal. Check both ratings against your peak and RMS current.
Inviaci: Full MPN, peak and RMS current, and the switching frequency.
What defines the part. Frequency, load capacitance, frequency tolerance and stability, ESR, package and temperature range.
Numbers to check. Load capacitance, ESR, drive level, tolerance in ppm, package.
Common trap. Load capacitance sets the frequency. Epson sells the FC-135 32.768 kHz crystal with 7.0 pF and 12.5 pF load options under different ordering codes (Q13FC13500001 and Q13FC13500005). A 12.5 pF crystal on a board designed for 7 pF runs off frequency, and the RTC drifts.
Inviaci: Full MPN, the load capacitors on the board, and the MCU oscillator spec.
Six problems buyers find after the order
Each of these looks fine on a quote and shows up at first power-up, in a test or in the field. We check for them before a line is quoted.
Parts do not fit the pads
Inch and metric case codes read as the same size
Case code system against the land pattern
Output rail ripples more than designed
X5R or X7R lost capacitance under DC bias
Capacitance at working voltage, from the maker’s curve
Capacitor bulges or dries out early
Operated near its maximum temperature, where rated life is shortest
Rated life and temperature, ripple current
Tantalum fails short at power-up
Working voltage too close to rated voltage
Derating, surge current, MnO2 or polymer
Converter overheats or its output sags
Inductor chosen by Irms; peak current saturates it
Isat and Irms against peak and RMS current
Clock starts late or runs off frequency
Crystal load capacitance does not match the board
Crystal CL against the load capacitors and stray
Worked example: matching a crystal to the board
A crystal sees the two load capacitors C1 and C2 in series, plus stray capacitance from the pins, pads and traces: CL = C1 × C2 / (C1 + C2) + Cstray.
Take a 12.5 pF crystal such as the FC-135 (Q13FC13500005) and an estimated stray of 3 pF. The two capacitors must give 12.5 − 3 = 9.5 pF in series. With C1 = C2 that is 19 pF each: 19 × 19 / 38 = 9.5, and 9.5 + 3 = 12.5 pF.
For the 7.0 pF version, the same stray leaves 4 pF, so C1 = C2 = 8 pF. Swap one crystal for the other and the board needs new capacitors. Send the crystal and the capacitor values and we check the match before we quote.
Worked example: two "10 µF" MLCCs
GRM188R61A106KE69D e GRM188R61E106MA73 are both Murata 10 µF X5R capacitors in a 0603 (1608 metric) case. The first is rated 10 V and ±10%; the second is rated 25 V and ±20%.
On a BOM line that reads “10 µF 0603”, either could be meant. Under DC bias they also behave differently, and the capacitance at your working voltage comes from the maker’s characteristic data for the exact part. We quote the code you designed in, and flag it when a candidate has a different voltage rating or dielectric.
Three requests we see, and how we handle them
Each started as a short message with a part number. What we check, and in which order, decides whether the buyer gets a usable part or a second problem.
"Our 10 µF MLCC has a long lead time"
High-capacitance MLCCs go short in cycles. We quote distribution and independent stock with date codes, and list the same value and case from other makers as candidates, with the voltage rating and dielectric stated so your engineers can compare the bias curves.
"Reels of resistors at a fraction of the price"
Passives are small, cheap and easy to remark. We compare the reel label with the parts, check the date codes across the reel and the body against the datasheet drawing, and recommend a third-party test before a large order, quoted separately.
"Our crystal is EOL, can we use any 32.768 kHz?"
Not any. We match load capacitance, tolerance, ESR and package first. A crystal with a different load capacitance needs different capacitors on the board, and we tell you which values to check.
Where these parts go
A drive in a control cabinet and a handheld meter use the same passives, specified differently. These are the requirements that change by application.
Automazione industriale
Aluminium capacitors rated for high ambient temperature, 125 °C MLCCs and crystals with tight tolerance.
Controllo motori e robotica
Bulk capacitors with high ripple ratings, current-sense resistors and AEC-Q200 parts.
Energia e alimentazione
Power inductors with margin on Isat, tantalum and polymer output capacitors, precision resistors.
Edge AI & AIoT
Dense 0201 and 0402 MLCCs for decoupling, ferrite beads and MCU clock crystals.
Elettronica di consumo
Small-case MLCCs and resistors in full reels, with second sources where cost matters.
Audio e voce intelligenti
C0G capacitors and thin-film resistors in signal paths, ferrite beads on supply rails.
Why buyers send passives lines to us
Ordering code decoded
Case size, dielectric, voltage, tolerance and packing are checked against the datasheet on every line.
Second sources with rating differences
Candidates listed with the voltage, bias, current and load ratings that differ. Your engineers approve.
Distribution and independent stock compared
Factory lead time, distributor stock and qualified independent stock in China quoted side by side, channel named.
Lifecycle flagged
EOL and last-time-buy status shown per line, with date codes when a series is going away.
Original packing kept
Reels and cut tape as packed by the manufacturer, labels intact. Partial reels where the source allows.
Answer within 24 hours
A quote, or the specific questions that stop us quoting, within 24 hours of a complete enquiry.
Quality checks for passive components
Passives are among the easiest parts to remark, mix between date codes or pull from used boards. A reel can look right and hold two different values.
- Reel label, marking and date code checked against the manufacturer's scheme
- Body size and terminations compared with the datasheet drawing
- Mixed date codes, remarked bodies and used-board terminations rejected
- Reel quantity checked against the manufacturer's standard packing
- Original reels and moisture bags kept intact where the part calls for them
- Capacitance, resistance or ESR tests, X-ray or decapsulation by an independent laboratory when the risk calls for it, quoted before you order
Passive manufacturers we source
Murata
MLCCs, inductors, ferrite beads
TDK
MLCCs, inductors, ferrites, film
Vishay
Resistors, tantalum, film, inductors
Also Yageo, KEMET, Samsung Electro-Mechanics, Panasonic, Nichicon, Rubycon, Coilcraft, Epson, Abracon and Taiyo Yuden. Tutti i produttori
Passive component questions
Can you quote one passive part number?
Yes. Send the complete ordering code, quantity and target date. We reply within 24 hours of a complete enquiry with a quote or the questions we need answered.
Is 0603 the same size in inch and metric?
No. 0603 inch is 1608 metric. A metric 0603 is a 0201 inch part. State the system on the BOM, or send the dimensions.
Does a 10 µF 10 V X5R MLCC give 10 µF at 5 V?
Not in general. X5R and X7R lose capacitance under DC bias, and C0G does not. The loss depends on the exact part, so read its characteristic curve.
Can I replace a 7 pF load crystal with a 12.5 pF one?
Not without changing the load capacitors. Load capacitance sets the frequency, and a mismatch makes the clock run off frequency.
Do you sell cut tape and partial reels?
Often, where the source allows, at a higher unit price. The quote shows the price for the quantity you asked for.
Can you quote an approved second source?
Yes, from makers on your approved list or approved on the quote. Each maker’s part is a separate line with its own code.
Do you sell automotive-grade passives?
Yes, as the qualified orderable code. The AEC-Q200 grade and temperature range are stated on the quote line.
Can you kit passives with the rest of the BOM?
Yes. With BOM sourcing and kitting, the kit is labelled by line number and reference designator, and passives are quoted with the other lines.
How do you check passives from independent sources?
Visual inspection in-house against a documented checklist, including reel label, markings and date codes. Electrical tests, X-ray or decapsulation are done by an independent laboratory when the order needs it, quoted before you order.