How USB cables are made

One factory turns out 22,000 to 25,000 USB cables a day, and fewer than 1 percent fail inspection.

stations: 9
things upstream: 77
raw sources: 22
steps from the ground: 9

The short version

A USB cable has fine copper wires, some for power and some for data, each coated in plastic and wrapped in a foil and braid shield under a jacket. Factories cut this raw cable to length, strip the ends, dip them in tin and solder them to the connector by color. Plastic is molded over the joint in two stages, with electrical tests after each.

Draw the copper wire

Copper rod is pulled through a series of ever-smaller dies until it is a thin strand. Several strands are twisted into one flexible conductor.

Goes in
Copper wire
Insulate each conductor

Each strand passes through an extruder that coats it in a thin layer of plastic. Different colors mark power, ground and the data pairs.

Goes in
Polyethylene PVC
Twist and shield the pairs

Data wires are twisted in pairs to cancel interference. A wrap of aluminum foil and a braided shield go around the bundle to stop signals from leaking in or out.

Goes in
Aluminum foil Copper wire
Jacket the cable

The shielded bundle is fed through a second extruder that coats it in a tough outer jacket. The finished raw cable is wound on large spools.

Goes in
PVC Polyethylene
Stamp and plate the connectors

Presses punch metal contacts and shells out of sheet brass or steel. The contacts are electroplated with nickel and a thin gold layer to resist corrosion.

Goes in
Brass Steel Nickel Gold
Cut and strip the ends

Raw cable is cut to lengths such as 1 meter or 2 meters. The outer jacket comes off, the braid is folded back, the foil is removed, and the inner jacket is stripped to bare the conductors.
Tin and solder the wires

Each conductor end is dipped in flux and then in molten tin, and soldered to the matching connector pin by wire color. Some USB-C plugs also carry a small chip that tells the device what the cable can do.

Goes in
Solder Tin Microchip
Mold the inner shell

Plastic is molded over the soldered joint to hold the wires in place, and an iron shell goes on top. The cable gets its first electrical test here.

Goes in
ABS plastic
Mold the outer plug

A second molding forms the outer plug and strain relief. A final electrical test checks every line before packing.

Goes in
ABS plastic

End of the lineUSB cable

Worth repeating

The USB-C connector can carry up to 240 watts of power.
Nearly all bad cables caught early at one factory can be fixed in-house, which keeps waste down.