PCB Assembly Tips

Diodes and LED Designation

Half of all LEDs on designs submitted to Advanced Assembly are missing clear cathode markers. This forces us to put your projects on hold. Avoid delays with these best practice tips:

Diodes and LEDS should have the cathodes (-) end designated with a bar in the silk screen. Remember that the bar should be visible even after the diode or LED is soldered on the board. If the polarity mark indicates the Anode (+) instead of the cathode (as the case with multi-colored LED�s), the assembly notes should specify so.

Remember that the bar designates negative instead of positive.

For LEDs, use an "A" for anode and "C" for cathode in the silk screen.

Whenever possible, number the pins/pads of your connectors and odd components the same way the manufacturer of that component numbered them.

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Part Polarity

Failure to designate polarity on capacitors puts assembly projects on hold at least 30% of the time. Avoid pcb assembly project delays with this advice:

SMT Polarized Capacitors
Surface mount polarized capacitors should always have the positive pad designated with a bar or "+" in the silk screen.
Remember that the bar designates positive instead of negative.
Through-hole Polarized Capacitors
Through-hole capacitors should have a "+" in silk screen next to the positive pin's pad.
The positive pin's pad should be square, while the negative pin's pad should be round.