Assembly BGA soldering defects and solutions

Tin plating

Tin connection, also known as short circuit on printed circuit board during assembly, refers to the short circuit between solder balls during the soldering process, causing two solder pads to connect and resulting in a short circuit.

Solution: Adjust the temperature curve, reduces the reflux pressure, and improves the printing quality.

Fake welding

Fake soldering, also known as the Head in Pillow (HIP) effect during PCB assembly process, can be caused by various factors such as oxidation of solder balls or pads, insufficient furnace temperature, PCB deformation, and poor solder paste activity. The characteristics of BGA false soldering are difficult to detect and identify.

Solution: Need to confirm the cause of the false welding before resolving it.

Cold welding

Cold soldering is not completely equivalent to false soldering. Cold soldering is caused by abnormal reflow soldering temperature, which results in incomplete melting of the solder paste. This may be due to the temperature not reaching the melting point of the solder paste or insufficient reflow time in the reflow zone.

Solution: Adjust the temperature curve and reduces vibration during the cooling process.

Bubble

Bubbles (or pores) are not an absolute negative phenomenon on circuit board, but if the bubbles are too large, it can easily lead to quality problems. The acceptance of bubbles is subject to IPC standards. Bubbles are mainly caused by the air trapped in blind holes not being discharged in a timely manner during the welding process.

Solution: Use X-ray to check for pores inside the raw materials and adjust the temperature curve during PCB assembly.