LGA/QFN Solderability

摘要

LGA/QFN solderability can be a challenge, and with an increasing number of components produced in this format, care needs to be taken to find a suitable test method. In reality we mainly focus on the bottom surfaces of the packages, as the side sections of the lead frame are often not solderable. FIGURE 1 shows a package reflowed on a glass slide with the same solder paste used in production and the same stencil aperture design used for assembly. Clearly the wetting viewed through the glass is very poor. This would result in component float and open connections during assembly if the parts were used in production. This type of simple solderability test is practical for the shop floor or for researchers but does not provide the quantitative measurements suppliers want to see when faced with a part being rejected.