02170222| Datasheet

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Effects of Mechanical Stress Effects of mechanical stress
1 General Two types of mechanical stress are dominant in practice and can cause fractures or cracks:
Bending fracture

(forces that result when printed circuit boards are subjected to bending strain)
Fractures caused by forces exerted during component mounting

The figures show the different types of fractures.

Figure 1 1.1

Bending fracture patterns Bending fracture

Figure 2

Mounting fracture patterns

In a bending fracture (see figure 1 and 3), the crack runs obliquely (at an angle of approximately 45 ) from its meniscus end to the underside (end of the solder pad) of the component. The fracture is produced along the line of greatest stress.

Crack Solder

Glue dot

KKE0343-N-E

Figure 3

Typical bending fracture

The ceramic capacitor is clamped securely in place during soldering. When subject to bending stress, it is bent but simultaneously secured at the solder joints. If the force acting on the capacitor becomes too large, it breaks at precisely the point at which the greatest lever action is applied (typical fracture line). 1.2 Fracture during mounting

Mechanical stress can also occur during placement. Here the fracture usually runs from the upper to the lower side of the capacitor. Depending on the intensity of the stress, it may even be more heavily damaged, i.e. entire parts may break off (see figure 2). 217 10/02