Method of manufacturing plastic foils which are electrically conductive in one direction but insulating in other directions

• US 5,911,863 A
• Filed: 12/03/1997
• Issued: 06/15/1999
• Est. Priority Date: 12/07/1996
• Status: Expired due to Fees

• Current Assignee: Gsf-Forschungszentrum Fur Umwelt und Gesundheit
• Original Assignee: Gessellschaft Fur Schwerionenforschung MbH
• Inventors: Angert, Norbert, Dobrev, Dobri, Vetter, Johann
• Primary Examiner(s): Gorgos, Kathryn
• Assistant Examiner(s): Leader, William T.
• Application Number:
  US08/984,519
• Time in Patent Office: 559 Days
• Field of Search: 205/103, 205/104, 205/118, 205/122, 205/148, 205/161, 205/205, 205/223, 439/66, 439/91, 439/591
• US Class Current: 205/103
• CPC Class Codes: C25D 1/04 Wires; Strips; Foils
• CPC Class Codes: C25D 7/0614 Strips or foils
• CPC Class Codes: H05K 2201/0367 Metallic bump or raised conductor not used as solder bump
• CPC Class Codes: H05K 2201/10378 Interposers
• CPC Class Codes: H05K 2203/0733 Method for plating stud vias, i.e. massive vias formed by plating the bottom of a hole without plating on the walls
• CPC Class Codes: H05K 3/205 using a pattern electroplated or electroformed on a metallic carrier
• CPC Class Codes: H05K 3/423 characterised by electroplating method

Abstract

In a method of manufacturing foils of plastic material which are electrically conductive in a transverse direction, but not in the plane of the foil wherein micropassages are formed in the foil by etching nucleus traces which are generated by exposure to a heavy ion beam, conductive layers are deposited on one side of the foil and the micropassages are filled by electrolytic metal ion depositions from the other side until caps are formed on the passages. After dissolving the two conductive layers, the steps are repeated to form caps also on the passages at the other side of the foil so as to provide for good contacting capabilities at both sides of the foil.

Claims

1. A method of manufacturing foils of plastic or other insulating material, which are electrically conductive in a z-direction and insulating in an x/y direction, wherein the z-direction extends essentially normal to the foil plane and the x/y directions are in the plane of the foil, said method comprising the steps of:

a) irradiating a foil with a beam of high energy ions in the z-direction such that said high energy ions completely penetrate said foil and generate nuclear traces,

b) etching the so-generated nuclear traces so as to provide micropassages of a desired diameter,

c) applying a conductive first layer by sputtering or vapor deposition on one side of said foil with said micropassages whereby said micro passages remain open, that is, said first layer does not enter into said micropassages,

d) applying an insulating cover layer to the other side of said foil,

e) applying a second conductive layer onto said first conductive layer by galvanic deposition from an electrolyte and connecting said first layer as a cathode whereby said micropassages are closed by overgrowth on this one side while the micropassages as such, however, remain open,

f) removing the cover layer on the other side of said foil and galvanically depositing metal ions out of an electrolyte in the micropassages from said other side wherein said second conductive layer is used as a cathode until said micropassages are completely filled forming metal filaments and caps are formed on top of the micropassages at said other side, which caps are not in contact with one another,

g) dissolving the first and second conductive layers on said one side wherein, however, the metal filaments with their caps remain,

h) applying a first conductive layer on said other side of said foil, where said caps are disposed, by sputtering or vapor deposition,

i) galvanically depositing from an electrolyte on said other side a second conductive layer on the other conductive layer and connecting said first conductive layer as a cathode,

j) galvanically depositing from an electrolyte metal ions on the filaments in said micropassages on said one side using said first conductive layer on said other side as a cathode until caps are formed on said micropassages on said one side, which caps are not in contact with one another, and

k) dissolving the conductive layers applied to said other side in the steps h) and i), such that the filaments in said micropassages and the caps at the opposite ends of the micropassages remain.

2. A method according to claim 1, wherein at least during one of the steps e), f), i), and j), said electrolyte is subjected to ultrasound vibrations.

3. A method according to claim 1, wherein a wetting agent is admixed in one of said electrolytes.

4. A method according to claim 1, wherein said conductive filaments in said micropassages with said caps are not soluble in said solutions in which said layers are dissolved and said electrolytes, said solutions, and said foil are further so selected that the foil is not attacked by said electrolyte or said solutions, which are used to dissolve said layers.

5. A method according to claim 1, wherein electric current flow is applied during galvanic deposition in a pulsed fashion.