Infineon PG-TO220, Руководство пользователя

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Additional information 26 of 31 Revision 4.0
2021-10-11
Recommendations for board assembly of Infineon transistor outline
type packages
Inspection
6 Inspection
6.1 Optical solder joint inspection
Irrespective of the specific geometry of a TO SMD gullwing lead, the solder joint is generally considered to be of
good quality when the heel region is wetted up to a certain height and additionally the sidewall is sufficiently
covered by solder.
Figure 19 and Figure 20 shows optical side-views of two properly soldered packages with
gullwing leads of different geometries. The tips of the gullwing leads have bare copper (e.g. cut edges) that is
not intended to wet by design according to the IPC-A-610 [7].
The visual inspection of the solder joints of the outer, gullwing-shaped terminations with conventional
automated optical inspection (AOI) systems is a standard procedure. According to IPC-A-610 the top side of a
gullwing lead as well as the cut edges at the toe are not taking part in the solder joint formation [7].
For engineering tasks, cross-sectioning can provide detailed information about the solder joint quality. Due to
its destructive character, cross-sectioning for monitoring purposes is naturally not practical.
Figure 19 Example of a properly mounted HSOG-8 package.
Figure 20 Example of a properly mounted TO263-7 package.
In order to reach an optimal TO THD solder joint, it has to be assured that a metallized via is filled properly. This
cannot be detected by visual inspection, only by X-ray and/or examining cross sections.
For further information about the acceptability of electronic assemblies inspected optically, please also refer to
the IPC-A-610 document [7].