Package Mounting Methods
5. Processes prior to mounting
Lead shaping/cutting process
Before mounting semiconductor devices on the printed circuit board, the external leads must be bent, shaped, and/or cut.
During this process, if stress is applied to the device body, damage such as leads breaking off or disconnection of internal
wiring may occur, which reduces reliability. In particular, there may be large effects on the seal characteristics of the
border between the external leads and the package for hermetically sealed types or on the moisture resistance for plastic
sealed types. Although no problems may occur at that point, the service life may be reduced. Therefore, care should be
given to the following points during lead processing:
1) When bending external leads, fix the base of the lead in place before bending the lead so that no stress is applied to the
device body. (Figure 5)
2) When performing mass-forming using molds, consider using systems such as a lead holding device so that no stress
will be applied to the entire component. (Figure 6)
3) When bending leads for glass-sealed types, either make the bend at a minimum of distance (a) from the glass body side
or use a clamp to hold the lead firmly. (Figure 7)
4) Bend the leads at a distance of at least 2.5 mm from the base of the lead. Also, keep the bend angle to within 90°C and
make the bend radius at least 0.75 mm. In addition, do not bend the leads toward their thicker side. (Figure 8)
5) The pulling stress along the axis of the lead wires and the bending strength are specified according to the lead diameter
or cross-sectional area. Do not apply loads which exceed these specified values.
6) Depending on the shape of the forming jig, the jig may cause damage to the plating surface on lead wires, reducing
reliability. Be careful when using such jigs.
Forming mechanism
Leave space.
Diode body
Bending radius: R0.75
W: Holding mechanism
Figure 5 Bending external leads
Figure 6 Bending using a mold
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