It is well known that in the BGA chip rework process, there are three key factors directly affecting the success rate of BGA rework: placement accuracy, precise temperature control, and prevention of PCB deformation. Apart from these, there are other factors as well, but these three are particularly crucial and challenging to manage. Let’s delve into the key factors that directly impact the success rate of BGA rework.
- Ensuring Placement Accuracy During BGA Rework
It is essential to ensure a certain level of placement accuracy when soldering BGA components to prevent solder voids. During BGA component soldering, there is a self-centering effect of the solder balls during heating, allowing for slight deviations. When placing the chip, overlapping the center of the housing with the center of the silk screen outline can be considered as the correct placement position. In the absence of an optical-grade BGA rework station, placement accuracy can also be judged based on the feel of moving the BGA chip (although this method is subjective and varies from person to person). Optical-grade BGA rework stations enable clear alignment of BGA components with solder pads and automatic soldering. Currently, most BGA rework stations in China use upper and lower hot air with infrared preheating at the bottom. Therefore, it is necessary to use scientifically designed nozzles to avoid moving the BGA during heating.
- Control of Required BGA Rework Temperature and Duration
Successful rework requires a rework temperature curve that matches the specific requirements of the BGA component. It is crucial to control the temperature and duration within the range that the BGA component can withstand. Under standard conditions, leaded soldering should be below 260°C, and lead-free soldering should be below 280°C. Inaccurate temperature control or large temperature fluctuations can easily damage BGA components. Prolonged heating or excessive rework frequency can lead to oxidation and reduce the lifespan of BGAs.
- Sufficient Preheating to Prevent PCB Deformation
During BGA component soldering or removal, heating only the corresponding BGA component can result in significant temperature differences between the BGA and its surroundings, leading to PCB deformation or damage. Therefore, it is necessary to fix the board and the area where the BGA is located during BGA rework. Typically, BGA rework stations use bottom nozzles to support the PCB, providing adequate support during rework. If using a hot air gun for soldering, the board must be fixed to prevent deformation during heating. Additionally, the entire PCB should be preheated in advance to reduce temperature differences and prevent deformation.
By mastering these key factors during BGA rework, the success rate can be significantly improved. It is also essential to ensure that the BGA rework station used meets the requirements for rework. We recommend Silman Tech’s fully automatic BGA rework station DEZ-R880A. For pricing inquiries, please contact our website customer service for online consultation.
