copper and have a thickness ranging from 1 um to 36 um further the bonding force between the release layer 201 and the carrying board 200 is greater than the bonding force between the release layer 201 and the first metal layer 202 the release layer 201 is only temporarily bonded to the first metal layer 202 so as to facilitate subsequent separation of the release layer 201 from the first metal layer 202 by an external force alternatively referring to fig2 a u2032 the carrier 20 has a carrying board 200 a second metal layer 203 formed on each of two opposite surfaces of the carrying board 200 a release layer 201 formed on the second metal layer 203 and a first metal layer 202 formed on the release layer 201 the carrying board 200 can be made of an organic polymer material such as bismaleimide triazine bt alternatively the carrying board 200 can be a copper clad laminate ccl with a dielectric material such as prepreg formed on two opposite surfaces thereof the second metal layer 203 can be made of copper and have a thickness ranging from 5 um to 40 um the release layer 201 can be made of an organic material such as a release film a metal material such as nickel or an inorganic material such as nickel oxide in other embodiments a copper foil bonded with a release layer as provided by companies such as mitsui nippon denk furukawa or olin can be used the first metal layer 202 can be.