💣 Electrolytic capacitor rupture
caution
Where you meet it: Aluminium electrolytics during hot-air work
What you need to know
- Heating a sealed electrolytic boils the electrolyte and blows the vent — or the can, if the vent doesn't work. Aim hot air at the board, not at the caps, and stand out of the line of fire.
- Reverse-charging or over-voltage ruptures them violently.
- Electrolyte is a skin, eye and respiratory irritant; some formulations smell strongly of ammonia or fish. Flush immediately.
- Large ones store lethal charge — see stored high voltage.
The rule: Don't heat a capacitor directly with hot air at close range.
Components this applies to
Arcade PCBs / JAMMA Boards
Au 0.05–0.20 g per board ≈ 0.09 g/lbCu ~45 g/lbAu ceramic gold-lid customs (FD1094
C
Enterprise Switches, Line Cards & Optics
Au 0.15–0.6 g per large line card ≈ 0.075 g/lbCu ~70 g/lbBase chassis backplane
C
Instrument clusters & head units
Au 0.008–0.100 g per unitAg 0.2–0.6 g in a premium head unitPd 0.02–0.06 g in a premium head unitCu 20–500 g
C
Xenon HID ballasts & LED drivers
Au 0.003–0.015 g per ballastCu 30–90 g in the HV transformer and inductorsAg trace in thick-film and solder
C
Aluminium electrolytic capacitors
Base aluminium can
D
Power supplies
Au 0.005–0.03 g/lbCu 30–60 g per transformerAg in the relay
D