Transfer lamination of vapor deposited foils, method and product

DETAILED DESCRIPTION OF THE INVENTION As illustrated in FIG.
1, the product of this invention is a laminate 10 comprised of a substrate 12 having a foil of copper 14 adhering thereto.
Foil 14 consisting of a vapor deposited film 15 and an electrolytically deposited bonding layer 16 has a surface 17 of irregular nodular appearance embedded in substrate 12.
Thus, nodules or dendrites 20 project from layer 16 and have club-headed portions 21 formed on them which provide re-entrant cavities for mechanical interlocking of foil 14 with substrate 12.
FIG.
2 illustrates the preferred method of this invention.
First, an aluminum carrier sheet, preferably of thickness from one to seven mils but possibly thinner or much thicker, is coated with a suitable substance which tends to form a relatively weak bond with copper.
Such substances, known and designated herein as release agents, are silicon dioxide, silicon oxide or soda-lime window glass or other materials capable of serving this purpose satisfactorily.
A coating of silicon dioxide may be applied by sputtering, chemical vapor deposition or electron beam evaporation techniques known to those skilled in the art.
Once the aluminum carrier sheet is suitably coated, a copper coating is applied thereto by sputtering or another vapor deposition process.
The deposited coat is suitably an ultra-thin film, but may be much thicker as up to 25 microns.
The advantage of vapor deposition is that a smooth, continuous and virtually pinhole-free coat of copper will result even in such thin sections.
The next step in the process is the electrolytic treatment of the exposed surface of the copper coat to promote bondability.
As is well known greatly increased mechanical interlocking of a copper film or foil to a glass epoxy substrate can be achieved by altering the morphology of the copper surface that is to be bonded.
One well known method of accomplishing this is described in an article which appeared in the "Transactions of the Institute of Metal Finishing" (Vol