The present invention provides methods of drying radiofrequency-activatable inkjet inks, methods for customizing the radiofrequency parameters of an RF source based on pre-selected printing conditions, and methods for selecting or formulating an RF inkjet ink composition based on pre-selected printing conditions andor printing equipment. Moreover, since the provision of these recessed portions allows an increase in the contact area of the adhesive layer with the substrate and the heat spreader, it can help increase the adhesive strength to provide the heat spreader more securely adhered in position on the substrate. The first material portion has a thick parallel-surface portion including opposite surfaces parallel to each other.