" The heat-induced mechanical stress can be compensated by expansion of the elements. " Note the word CAN, not how it is to be done, or can be done or doing it this way extends the life of the module. Or due to poor quality control the life may be shortened.
It seems like a good idea, allowing the various components to move about due to their different expansion coefficients, but I would not bet my shirt on the technique on the basis of this article.
frank