D-MAX DMC-20SEC Manual de usuario descargar pdf (Pagina 20)

achieved, when it cools and solidifies. As a result of this, the microstructure that is created has

a greater surface roughness than in the previous case: as the eutectic melt ebbs away, the

intermetallic crystals that were the first to solidify create a more irregular surface. This surface

scatters light much more than the smoother, more even surface of the tin-lead solder; in other

words the proportion of diffuse reflection will be greater than that of specular reflection.

An attempt to measure the two solders with AOI equipment using the same settings will

probably result in several errors, because after the necessary image conversion procedures the

images made by the equipment will differ. For this reason, it would clearly be useful to calibrate

the AOI equipment specifically for the different solders.

In what follows we present a series of images of tin-lead eutectic and lead-free Sn-Ag-Cu solder

alloys made using a scanning electron microscope (SEM). This instrument is not suitable for

measuring the surface roughness, but it does provide an accurate, high-resolution image of

the examined surfaces and of the two solder alloys with differing composition and surface

roughness, showing the differences in height and material with spectacular contrast.

Figure 8. Tin-copper-silver phase diagram

Materials Science - Advanced Topics

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D-MAX DMC-20SEC Manual de usuario Pagina 20