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Optimization of BGA, BGA rework and the main influencing factors

Writer:KrystalSource:Shuttle Star Date:2016年7月4日 15:06

Now there are many types of BGA package component, such as computer graphics,  South Bridge  and North, CPU, there are products such as mobile phones, projectors, televisions, servers. Summarize key factors that affect the success rate of BGA rework the main points.


Factors can be divided into three main points:

1.prevent deformation of PCB;

2.precise temperature control;

3.the accuracy of the mount.



These three aspects are hard to grasp, so there is a separate list for it.

First: when welding or remove the BGA components, because hot air heating heating BGA components separately. BGA are easily at this point with the surrounding temperature is too large, easily deformed, damaged the Board. BGA rework needs to fix the Board and the BGA site. BGA rework station BGA rework will generally use lower wind up against the PCB Board, and the lower hot air can play a supporting role. If you use air gun desoldering, you'll need to fix the Board to prevent deformation caused by heating directly cause damage to the PCB.
                                       Wind up diagram

                                        12*12mm bga rework


Second: reasonable, quality repair repair of the need to adapt to the temperature curve. Control the temperature and time, to BGA can bear range. Typically, a lead of less than 260 ℃, no lead and less than 280 ℃. If the temperature control is not precise enough, large temperature fluctuations, so it is easy to damage the BGA components. Heating time should not be too long, rework number should not be excessive, in high temperature situations can cause oxidation of BGA, for a long time will shorten the life of BGA.


Third: soldering BGA components need to guarantee placement accuracy, or it will cause blank welding. Xiqiu welding heat with some effect in, allowing a slight deviation. When mounted, the casing of the device Center coinciding with the printing center of bounding box approximation, as a mounting location is correct. In the case of not using optical BGA rework station, also according to the texture of the BGA is moved to determine whether contact (this is subjective, everyone's feelings are not necessarily the same). Optical BGA rework station can see BGA components and pad alignment and automatic welding. Because currently the BGA rework station using the upper and lower parts of the hot infrared Preheat mode at the bottom, so you need to use properly designed wind up, preventing heating hot air moves the BGA.


                                Optical BGA rework station to bitmap


There are other factors that affect the quality of BGA rework, as follows:

1. after opening the BGA components if not placed in moisture-proof cabinets, need to bake preheating the BGA (time of 8-20 hours at a temperature of 80~100℃). Prevent cracking in the BGA rapidly when heated. Similarly PCB needs to warm up to some extent.

2. when welding solder balls, you need to ensure the quality of solder balls. Avoid using oxidation of solder balls or other impurities on the contamination of solder ball. Industrial production, brush the paste to note the mix paste, temperature and so on.

3. when welding, in uniform need to brush on a PCB Board, the right amount of solder paste, too much easy to cause a short circuit.

4. mobility, good welding properties of lead-containing solder balls, but not environmentally friendly. Currently used only in military fields will lead, normally choose lead-free rework.

5. perimeter of the BGA component when welding, use wind up, preventing heat to other components, components and dense needs more attention, like the phone is more intensive.

6. There are fixed by glue on the BGA components, and commonly used way is to heat and pry the colloid.

7. remove end, move the BGA component when best to use a vacuum pen, avoid the use of metal tweezers, which may damage the chip.8. avoid press BGA components, prevent BGA damage or cracks;


TypeInfo: Tech

Keywords for the information:BGA  BGA wrap  BGA components  Remove the BGA 

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