BGA rework step one:
1. Appropriate small steel plates are mounted on the engineering samples and placed on the pads. The thickness of the small steel plates is generally between 100um and 200um. The size of the steel plate is limited to the size outside the surrounding area, so it is usually only a little larger than BGA.
2. Solder paste is required to be printed on the printed circuit board, but under normal circumstances it is a rework condition. It cannot be done without solder paste. Under normal conditions, just apply a layer of flux.
BGA rework step 2:
1. Use image pairs to ensure accurate soldering of parts during reflow soldering.
Especially when the position of sBGA and CSP needs to rely on this function, unlike the large-size BGA that uses some manual or mechanical centering, it can still be due to the cohesion and automatic centering position of tin-lead.
BGA rework step three:
1. The BGA back welding of the engineering sample board is a local heating method of the substrate. In addition to relying on a specially designed heating cover, there is a bottom heater to assist in preheating the part under the substrate. The heating process is similar to ordinary reflow soldering. Therefore, the design function of the heating mantle is very important, especially when the parts themselves or the surrounding parts and the substrate will not be damaged due to overheating or unevenness.
Whether it is the surface of the reworked part or the soldering on the substrate, the surface of the residual tin or oxidized material is properly cleaned. Ensure the reliability after welding.
Since the flux required in the soldering operation can be supplied by solder paste printing, it can also be directly attached to the flux and used without solder paste printing. The solder paste supplier will provide various sizes of tin powder according to the foot density of the part. .
After the BGA ball is planted on the engineering sample board, the flow soldering must be tested by the instrument to detect the adhesion strength after welding to avoid abnormalities caused by excessively weak stress.
Inspection after bga reflow soldering: Due to the characteristics of solder, the size and height of bga reflow soldering will change significantly. Therefore, this feature can be used to test the reliability of soldering after reflow soldering.