பொரி(றி)யால் வீணாகும் Electronics | PopCorn Effect
4 Minutes
Popcorn effect in electronics explained for students, showing how moisture damages circuit boards and how baking prevents it. A Tamil science lesson.
- How trapped water turns to steam to make puffed rice and popcorn
- How hygroscopic PCB materials absorb moisture from the air
- Baking circuit boards at 120 to 130 °C to prevent damage
What this lesson teaches
The popcorn effect in electronics is the cracking and physical damage that happens when trapped moisture inside a printed circuit board suddenly turns to steam during high-temperature soldering. This rapid expansion creates intense internal pressure, causing the board to burst open much like a kernel of corn popping in hot oil.
How popping works in food
- Grains like rice and corn have internal moisture sealed beneath their outer surface.
- When heated in hot sand or oil, this trapped water rapidly vaporizes into expanding steam.
- High pressure builds up within the sealed grain because the steam cannot escape easily.
- The grain shell bursts open violently, producing puffed rice (pori) or popcorn.
- Food items like sun-dried crisps (vadagam) can also burst dangerously in hot oil if internal moisture is not dried completely beforehand.
Why circuit boards trap water
Everyday electronic devices such as televisions, mobile phones, and laptops rely on printed circuit boards, known as PCBs, to hold processors and other soldered components. Many circuit boards are made by combining silicon with resins such as polyimide. Polyimide is hygroscopic, which means it naturally absorbs moisture from the surrounding air while boards are stored in factories. Moisture can also enter the board during manufacturing stages like copper plating.
How the popcorn effect occurs
Attaching components to a circuit board requires soldering at temperatures higher than 200 °C. When a moisture-laden board hits this intense heat, the water trapped inside its layers turns into steam almost instantly. The expanding steam generates intense pressure within the board, causing it to crack, split, and burst at the soldering point. This damage can ruin the entire board and cause the electronic device to fail.
Preventing defects by baking
Electronics factories prevent the popcorn effect by using a controlled drying method called baking before any soldering begins.
- Circuit boards are placed in an oven and heated between 120 °C and 130 °C for two to three hours.
- The exact baking temperature depends on the board material and its thickness.
- This gentle heating allows moisture to evaporate slowly and escape without creating destructive pressure.
- Once the boards are completely dried out, electronic components can be safely soldered at high temperatures.