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28 SMT Magazine • June 2015 The acceptance criteria are defined in IPC- A610 in order to distinguish between good and bad solder joints after successful soldering. Table 1 gives an overview of the criteria in excerpts: It is now necessary to select testing technol- ogy which meets the specified acceptance crite- ria. Based on the example of a multi-row con- nector (Figure 2), the following table provides an overview of the test coverage of AOI and 3D AXI systems. AOI systems are highly suited to assessment of the peripheral wetting of the pin and the sleeve and to evaluation of the wetted connect- ing surface on the solder side of a THT solder joint. The disadvantage of a traditional 2D AOI or an innovative 3D AOI system here, however, is that it is often only possible to assess the sol- der side because the pins on the component side are usually concealed by the component body itself. An assessment of the solder joints on the component side is therefore not possible with an AOI system. The solder penetration also re- mains hidden from traditional AOI technology. A modern 3D X-ray system can provide a remedy. The 3D X-ray inspection not only makes the solder joints on the component side (i.e., below the component housing) visible, but is also able to calculate the solder pen- etration and the solder volume. In addition to 3D X-ray technology, 2.5D X- ray imaging (oblique radiation) is also used to test the solder penetration. However, assessment Table 1: overview of selected acceptance criteria for ThT solder joints according to iPc-A610e. figure 2: connectors shot from above and below using Aoi. Feature In-LIne SOLDeR PeneTRATIOn TeSTInG WITH 3D X-RAy InSPeCTIOn continues