Jellybeans on us
What's in the jellybean jar
Engineers call them jellybeans: the resistors, capacitors, inductors and ferrite beads scattered across every board. At CopperPCB they're on us. Free doesn't mean generic, so here's exactly whose parts we load, and why.
Why the brand matters
A jellybean costs a fraction of a cent, which makes it tempting to buy whatever is cheapest. But a board is only as reliable as its weakest part, and a cracked capacitor or a drifting resistor fails just as hard as a bad chip. We look for three things: low ESR, precision over temperature and long life. Then we buy from the makers who have been delivering all three for decades.
Every jellybean we place is 0402 or larger.
The jar: on us
These come from our stock at no charge. You pay only to place them.
Ceramic capacitors
All our ceramic capacitors come from Japan. Japanese makers lead the world in multilayer ceramic capacitors (MLCCs), the tiny chips that make up most of the parts on a modern board.
What matters: low ESR, stable capacitance under DC bias and temperature-
MurataKyoto, Japan · 1944
Akira Murata rented a former dye works in central Kyoto in 1944 and started making titanium-oxide ceramic capacitors for radios. His rule was to stay one step ahead and win on quality, not price. Murata is now the world’s largest maker of MLCCs.
Why we like them: The broadest range of low-ESR ceramics anywhere, with published DC-bias and temperature curves for nearly every part, so the value you design with is the value you get.
-
TDKTokyo, Japan · 1935
Two professors at the Tokyo Institute of Technology invented ferrite, a magnetic ceramic, and Kenzo Saito founded TDK in 1935 to commercialize it. It was a university spin-off decades before that was common, and ceramics are still its core.
Why we like them: Rugged automotive-grade parts and soft-termination options that resist cracking when a board flexes.
-
Taiyo YudenTokyo, Japan · 1950
Hikohachi Sato founded Taiyo Yuden in 1950. The name means “sun dielectric.” Its materials know-how led it to make the world’s first recordable CD in 1988, and today it is one of the leading MLCC makers.
Why we like them: Very high capacitance in small cases, which keeps bulk decoupling in 0402 and 0603 instead of larger parts.
Bulk capacitors
For the larger values ceramics can’t reach, we use aluminum electrolytic and polymer capacitors from Japan’s long-life specialists.
What matters: long life at high temperature, low ESR, ripple current-
Nippon Chemi-ConTokyo, Japan · 1931
Nippon Chemi-Con commercialized Japan’s first electrolytic capacitors in 1931 and went on to supply the first capacitors made for transistor radios. It now holds the largest share of the world aluminum electrolytic market.
Why we like them: Long rated life at 105°C and its own aluminum foil production, so quality is controlled from the raw material up.
-
NichiconKyoto, Japan · 1950
Founded in Kyoto in 1950 and named Nichicon in 1961, it has specialized in capacitors for more than seventy years and supplies power supply, audio and automotive makers worldwide.
Why we like them: Consistently low ESR and long-life series that hold up in hot, high-ripple power supplies.
-
PanasonicOsaka, Japan · 1918
Panasonic’s component division is one of the pioneers of conductive polymer capacitors.
Why we like them: Polymer capacitors with very low ESR that don’t dry out the way wet electrolytics eventually do.
Resistors
A resistor is supposed to be the most boring part on the board. The good ones stay boring across temperature, through power surges and over years of service.
What matters: precision over temperature, surge tolerance, consistency-
YageoTaipei, Taiwan · 1977
Pierre Chen founded Yageo in 1977. It grew into the world’s largest maker of chip resistors, then bought Pulse Electronics in 2018 and KEMET in 2020.
Why we like them: The volume king. Yageo is the industry standard for general-purpose resistors, with tight, consistent tolerances and every value always in stock.
-
VishayMalvern, Pennsylvania · 1962
In the 1950s Dr. Felix Zandman, a physicist, invented the Bulk Metal Foil resistor. He founded Vishay in 1962 to build it, then spent decades buying legendary resistor makers, including Dale, Draloric and Beyschlag.
Why we like them: The precision specialist. Vishay leads in high-reliability foil and thin-film resistors for military, aerospace and instrumentation work, where drift over temperature matters most.
-
PanasonicOsaka, Japan · 1918
Konosuke Matsushita was 23 when he started the company in 1918 in his rented house in Osaka, with his wife and her teenage brother. Its first product was an improved attachment plug.
Why we like them: The automotive standard. Its ERJ thick-film and ERA thin-film series include AEC-Q200 anti-surge parts trusted in engine control modules, EVs and industrial automation.
Inductors
Power inductors decide how efficient and how quiet a switching regulator is. Cheap ones run hot, and they saturate suddenly when load current peaks.
What matters: low DC resistance, soft saturation, low core loss-
CoilcraftCary, Illinois · 1945
Coilcraft started in 1945 winding custom coils for the television makers clustered around Chicago. It is still privately held and headquartered outside Chicago.
Why we like them: Molded power inductors with very low DC resistance and soft saturation, excellent online loss calculators, and famously fast free samples.
-
Würth ElektronikWaldenburg, Germany · 1971
Reinhold Würth started Würth Elektronik in 1971 as a division of his family’s fastener business, making circuit boards. Its eiSos division grew into a major maker of passive components.
Why we like them: Thorough datasheets and its REDEXPERT tool, which predicts real losses in your circuit rather than ideal numbers.
-
TDKTokyo, Japan · 1935
TDK shipped its first ferrite cores in 1937, the first ever used in radio equipment. That same ferrite expertise shows up in its inductors.
Why we like them: Compact metal-composite power inductors that handle high current in small footprints.
Ferrite beads
Ferrite beads keep noise off power rails and signal lines. A bead is only useful if its impedance holds at the current it actually carries.
What matters: impedance at frequency, rated current, low DC resistance-
MurataKyoto, Japan · 1944
Murata’s BLM series is the bead many engineers reach for first.
Why we like them: Detailed impedance curves at real DC bias, so the bead filters as designed.
-
TDKTokyo, Japan · 1935
TDK was founded to commercialize ferrite, so beads are about as close to its roots as a product gets.
Why we like them: A wide range of high-current beads for power rails.
-
Würth ElektronikWaldenburg, Germany · 1971
Würth’s WE-CBF beads are a staple of EMC test labs.
Why we like them: Clear documentation and samples that make EMC fixes quick.
Need a specific part number?
If your design calls for a particular passive, such as a precision resistor, a high-voltage capacitor or a specific power inductor, mark it on your parts list when you request a build. We'll confirm whether it's in the jar or whether you should add it to your cart.
Bring the chips. We'll bring the jellybeans.
Jellybeans $0, published rates for everything else. Made in the US with world-class ingredients.
Request a buildMore from the bench
Brands we like to see in your kit
Chips, connectors and LEDs make your board yours. If you're choosing them, these are the makers we'd pick.
The true cost of buying your own jellybeans
Passives cost pennies. Buying them for a prototype run costs a lot more than that. Here is where the money and time really go.
Designing for 0402: a practical guide
Footprints, tombstoning, vias, fiducials and capacitor derating. How to lay out a board that builds cleanly with 0402 and larger parts.
How to ship moisture-sensitive chips
What MSL ratings mean, how long a chip can sit out of its bag, and how to pack your kit so nothing needs baking.