Because the qfn's solder joints are below the packaging body, and the thickness is thin, X -Ray cannot detect the QFN solder point less tin and the opening of the road. It can only be judged as possible by the external welding joint situation. However, the current QFN welding The determination standards of the point part of the point part of the side have not yet appeared in the IPC standard. With no more ways for the time being, the testing stations that rely on post -production will be relying on the after -production section to judge the quality of welding.

　　From the X -Ray images in Figure 6, the difference between the side part is obvious, but the image of the bottom part of the performance of the welding point performance is the same, so this brings problems to the X -ray detection and judgment. The use of electric iron to add tin, which increases only the side part, which impacts on the bottom part, X -Ray still cannot judge. Judging from the local magnifying of the appearance of the weld, there are still obvious filling parts on the side.