New developments in the adhesion promotion of electroless Ni or Cu films to polyimide substrates - Polyimides and Other High Temperature Polymers - page 307

Figure 12. Fragmentation test. Dependence of the relative electrical resistance of 200 nm thick Ni
films on the applied strain. Curves (a) and (b) are for Kapton ® HN substrates which were chemically
pretreated (H 2 SO 4 / CrO 3 solution), and then sensitized / activated by immersion successively in
acidic SnCl 2 and PdCl 2 solutions. A reasonable adhesion at the metal / polymer interface is obtained
in the case (a) while a poor adhesion is achieved in the case (b). Curves (c) and (d) were obtained by
integration of curves (a) and (b), respectively. Area [in (%)²] on the right ordinate scales is the result
of these integrations.
fore the electroless metallization does not provide (a) or (b)-type curves with a
good reproducibility. In the present example, curve (a) is characteristic of a rea-
sonable adhesion of the Ni film to its substrate, despite a nearly immediate onset
of the primary fragmentation process. On the other hand, curve (b) bears witness