A clad planchet is a bit different than the normal metal or alloy planchet. The United States uses an inner core of pure copper that is bonded on either side by a layer composed of an alloy of 75% copper and 25% nickel. This bonding is performed by a bonding mill.
The Eisenhower dollar coins from 1971 to 1976, minted as proofs from San Francisco were also clad planchets , but had a different composition. The inner core was .791 copper to .209 silver alloy bonded to layers made from an alloy of 80% silver and 20% copper.