BGA rework generally requires a set temperature profile, with different temperatures at different stages. Failure to adhere to these temperature profiles may result in damage to the BGA chip or PCB board. This is a clear advantage of BGA rework stations over hot air guns. Sometimes, even if a BGA is successfully removed with a hot air gun, the uncontrolled temperature can shorten the lifespan of the BGA, causing damage that may not be visible to the naked eye but is still present.
When using a BGA rework station, it is generally necessary to set a temperature profile with at least 20 segments, and a heating time of 3-5 minutes. The heating rate for the preheating zone, ramp-up zone, reflow zone, and cooling zone varies, and the timing for each zone is also important.
- The first heating ramp, temperature from 75 to 155 degrees, maximum rate: 3.0 degrees/second.
- Preheat temperature from 155 degrees to 185 degrees, time requirement: 50 to 80 seconds.
- The second heating ramp, temperature from 185 to 220 degrees, maximum rate: 3.0 degrees/second.
- Maximum temperature: 225 to 245 degrees.
- Maintain above 220 degrees for 40 to 70 seconds.
- Cooling ramp maximum not exceeding 6.0 degrees/second.
When using a BGA rework station, if the PCB board bubbles, it can almost be determined that the board has been exposed to moisture. During heating, the steam expands, causing the board to bubble. This problem is particularly common in humid climates, especially in some regions of the southern hemisphere. The main reason is inadequate and uneven preheating of the bottom of the board during BGA removal. It is recommended to preheat the BGA and board together for a few minutes (generally 2-3 minutes) before reworking the board, ensuring that the board is dry before applying heat to remove the BGA.