Continue to place the lower layer to the heating platform. Power on the heating platform and set the temperature to 150℃. With solder paste melting, solder balls start to shape up. Once completed, power off the heating platform and wait for the lower layer to cool for 10 minutes.

Continue to apply BGA Paste Flux to the bonding pad.

Get the upper layer in position and power on the heating platform.

With the temperature of the platform reaching 150℃, continue heating for 1 minute. Once done, power off the heating platform. Wait for the motherboard to cool for 10 minutes.