Master Thesis - OUFTI-1

Figure 4.20: MAC matrix using the local mass smearing method
4.3.7 Application of a homemade method
Generally, the methods used in the previous sections, are applied to the entire PCB.
However, as already mentioned in section 4.2.5, these methods can be particularized to the
dierent categories of components and several methods can be applied on the same PCB.
The homemade method described here is based on this concept. It considers the following
simplications:
• The light components are completely neglected.
• The SMT components, including: the I 2 C − EEP ROM, the two MAX 890, the
MSP 430, the Crystal 32.768 kHz and the JT AG connector, are modeled using the
global mass smearing method. This solution was chosen because it is easier to apply
than the local mass smearing method and, with regard to the mass contributions of
these components, it brings the same level of accuracy.
• The heavy components, including only the P C 104 connector, are modeled using a
detailed FE model. This solution was chosen because, owing to its dimensions and
its properties, the P C 104 connector plays an important role in the PCB dynamic
response. So, it is better to model it entirely. To be able to create this particular
model, the properties of this connector are necessary. Its mass is easily obtained
by weighting it and has a value of 10.12 g, which leads to a density calculated in
Equation 4.3.2
95