Ball grid array (BGA) packages are becoming common for chips with large numbers of pins. In a BGA chip, the "pins" are arranged in a grid on the underside of the chip. Each pad has a little ball of solder affixed to it. You can only solder BGA chips using a process called "reflow" soldering. Reflow soldering involves placing the chip on the board, and then heating the whole board to the point where the solder balls melt. The heat requirements are fairly precise, and accurate reflow soldering requires expensive industrial machinery. However, you can solder BGA chips at home with a hotplate if you're comfortable with a higher possibility of error. Be prepared to ruin a few boards before you get this right.
- Skill level:
- Moderately Challenging
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Things you need
- Electric hotplate
Turn the hotplate up to 229 degrees Celsius (230 degrees Celsius.) You can consult the data sheet of your chip for its recommended soldering temperature, but 229 degrees C should work for most components. If your chip is RoHS compliant and uses lead-free solder, you'll need a higher temperature.
Give the hotplate a few minutes to heat up and then use a spatula to gently place the board on the plate.
Carefully place the chip on the board so that the solder balls on the underside of the chip are lined up with the pads on the circuit board.
Wait for the hotplate and board to reach soldering temperature. When the board is hot enough, the solder balls under the BGA chip will melt, soldering the chip to the board. You'll know the solder has melted when you see the chip settle onto the board. The surface tension of the solder will keep the chip in place and prevent the pads from bridging. Once the solder melts, give it a couple of seconds to allow the solder time to flow properly.
Use a spatula to remove the board from the hotplate. Lift up the board carefully so that you don't jerk the chip out of position. Set the board down somewhere it can cool safely, and don't disturb it until it's done cooling.
Tips and warnings
- If your hotplate isn't heating the board evenly, you can try covering the hotplate with a layer of clean, dry, finely-grained sand. The sand will distribute heat more evenly than the bare metal.
- You can't reflow solder a board with through-hole components on it because the component leads on the bottom of the board will lift it off the hotplate and prevent it from heating properly. Solder all your surface-mount components at once on the hotplate, wait for the board to cool, and then hand solder any through-hole components.
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