Method for forming a capacitor having a copper electrode and a high surface area aluminum inner layer

A method of forming a capacitor having a bimetal copper and aluminum structure, comprising:

• providing a bimetal foil comprising an aluminum layer attached to a copper layer;
• providing a sacrificial aluminum carrier;
• temporarily attaching the sacrificial aluminum carrier to the bimetal foil copper layer to form a sandwich, such that the aluminum layer and the sacrificial aluminum carrier are exposed, sufficient to protect the copper layer from attack in a subsequent treatment;
• treating the exposed bimetal foil aluminum layer in a manner sufficient to increase the surface area of said aluminum layer by at least one order of magnitude and not reveal any of the underlying layer of copper;
• forming a capacitor, wherein the copper layer is one electrode of the capacitor and the treated aluminum layer is in intimate contact with a dielectric layer of the capacitor;
• and
• separating the treated bimetal foil from the sacrificial aluminum carrier.

A method of forming bimetal copper and aluminum foil structure for embedding a capacitor in a printed circuit board, comprising:

• providing a bimetal foil comprising an aluminum layer attached to a copper layer;
• providing a protective foil layer, comprising a foil having at least an aluminum layer;
• temporarily attaching the bimetal foil copper layer to the protective foil layer to form a sandwich, such that the aluminum layers of the sandwich are exposed, and sufficient to protect the copper layer from attack in a subsequent treatment;
• treating the exposed aluminum layers of the sandwich to form deep pits in the bimetal foil aluminum layer sufficient to increase the surface area of the bimetal foil aluminum layer by at least one order of magnitude, and not reveal any of the underlying copper layer;
• separating the bimetal foil from the protective foil layer;
• and
• laminating the bimetal foil into a printed circuit board to form a capacitor, wherein the copper layer is one electrode of the capacitor and the treated aluminum layer is in intimate contact with a dielectric layer of the capacitor.

A method of forming a capacitor having a bimetal copper and aluminum structure, comprising:

• providing first and second aluminum foils, each comprising a first surface and an opposing second surface;
• temporarily attaching the first surface of the first aluminum foil to the first surface of the second aluminum foil in a manner sufficient to protect both first surfaces from attack during a subsequent treatment, and such that the second surfaces of both foils are exposed;
• treating the exposed second surfaces of both aluminum foils in a manner sufficient to increase the surface area by at least one order of magnitude;
• separating, after treating, the first aluminum foil from the second aluminum foil;
• plating, after separating, copper on the first surface of the aluminum foils to create one or more bimetal foils;
• and
• forming the capacitor from the one or more bimetal foils, wherein the plated copper is one electrode of the capacitor and the treated second surface is in intimate contact with a dielectric layer of the capacitor.

A method of forming a capacitor having a bimetal copper and aluminum structure, comprising:

• providing an aluminum foil having a first surface and an opposing second surface;
• protecting the first surface of the aluminum foil sufficient to prevent degradation during a subsequent surface modification treatment, and such that the second surface of the foil is exposed;
• modifying the exposed second surface of the aluminum foil in a manner sufficient to increase the surface area by at least one order of magnitude;
• unprotecting the first surface of the aluminum foil;
• providing a layer of copper on the aluminum foil first surface to create a bimetal foil;
• and
• after unprotecting, forming the capacitor from the modified bimetal foil, wherein the layer of copper is one electrode of the capacitor and the modified second surface is in intimate contact with a dielectric layer of the capacitor.