The present invention relates to a metal laminate which is broadly used
for a flexible wiring board or the like and an etching method therefor.
In particular, the present invention relates to a metal laminate which
includes a layer obtained by laminating a metal layer and an insulating
layer, where the insulating layer is subjected to an etching process,
wherein, in a surface of the metal layer which is positioned so as to
come in contact with the insulating layer, respective concentrations of
main metal element and oxygen element constituting the metal layer are
measured from the surface of the metal layer towards inside of the metal
layer in a time-elapsing manner according to AES (Auger electron
spectroscopy) and a value of the thickness of a metal oxide film of the
surface of the metal layer measured at a time when atomic concentrations
of the main metal element and the oxygen element constituting the metal
layer become equal to each other is in a range of at least 0 .ANG. to
less than 50 .ANG..According to the present invention, an etching time of
polyimide in the polyimide metal laminate can be calculated and a flexure
used for a suspension for a hard disc drive having a high productivity
can be provided.