Master Thesis - OUFTI-1

Figure 4.2: Example of dierences between the values provided by manufacturers and the
values determined by experimental tests [44]
The Young's modulus can be determined using a static bend test. However, it is important
to note that most PCBs are laminated and so, their properties may vary depending
on the direction of loading. Thus, the determination of the Young's modulus necessitates
three dierent tests, one according to each axis of the PCB. Figure 4.3 shows an example
of this type of test.
Figure 4.3: Illustration of the experimental set-up for a static bend test
The shear modulus of a PCB may most conveniently be determined through a torsion
test, as shown in Figure 4.4.
So, the shear modulus can be calculated using Equation 4.2.1:
G xy = 3 K t a b
4 t 3 (4.2.1)
where K t is the slope of the load displacement curve, a and b are the dimensions of the
specimen edges and t is its thickness.
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