Chapitre 1 : La fiabilité électronique
1.5. Conclusions
Les sources de la défaillance de l’électronique peuvent se résumer par le diagramme établi par l’équipe d’Ambat et présenté Figure 32. Nous y retrouvons l’eau, le champ électrique et la pollution.
Figure 32 : schéma de la synergie des facteurs de corrosion [29].
A notre connaissance, les études académiques et industrielles menées jusqu’à présent décrivent le phénomène de dégradation des PCB dans des conditions extrêmes d’utilisation, le plus souvent pour arriver de façon accélérer à une défaillance totale du PCB. Dans ce travail, nous avons fait le choix de nous rapprocher de la réalité et d’intégrer à notre étude les paramètres dits « normaux » de fonctionnement d’un PCB. Nous aborderons en particulier pour la première fois la question d’un vieillissement dans des conditions normales d’utilisation des PCB.
Bien que les techniques de mesure d’angle de contact et de spectroscopie d’impédance soient très largement rependues pour la caractérisation des processus électrochimiques, peu de tentatives ont été réalisées pour aborder de façon analytique la problématique du vieillissement des PCB liée à la pollution. Nous avons fait le choix de les mettre en œuvre et de les intégrer dans les dispositifs expérimentaux que nous avons développés.
D’un point de vue caractérisation de surface, les mesures de microspectrométrie Raman n’ont, à ce jour, jamais été réalisées, à notre connaissance, sur des PCB ou les polluants qui les détériorent. Nous avons également choisi de développer cette approche qui permet d’élargir encore le spectre des outils de microscopie, qui s’est avérée être une technique puissante pour l’étude des défaillances matériels.
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