US 4,668,532 A · System for selective metallization of electronic interconnection boards

Abstract

An improved process for selective metallization of insulating substrates, as for example in the manufacture of wire scribed interconnection boards, is provided. The substrates optionally include one or more holes or cavities for electrical connections. The process comprises applying an insulating, hydrophobic mask onto the surface of a suitable insulating substrate so as to leave exposed selected areas to be metallized, contacting the substrate with an activator solution for a sufficient time to deposit a catalytic species onto the exposed areas of the substrate and the mask and on the walls of the holes or cavities and thereby render them catalytic to the reception of metal, accelerating the catalytic species and preferentially removing essentially all of the catalytic species from the hydrophobic mask by contacting the substrate with a chelating agent in an alkaline solution having a pH between about 10 and about 14 for a time period sufficient to remove essentially all of said catalytic species from the mask, and then contacting the substrate with a metal deposition solution to metallize only the exposed catalytic areas of the substrate not protected by the hydrophobic mask.

Claims21

Dependent claims

In a process for depositing metal on a wire scribed circuit board having at least one insulated wire affixed to a surface of a substrate or imbedded therein and having at least a portion of the surfaces of the substrate covered with a hydrophobic mask and having at least one hole or at least one blind via in the substrate and intersecting the wire, wherein the walls of the hole or blind via and the intersected wire are metallized by metal deposition,

the improvement which comprises:
contacting the surface of the substrate including said walls with an activator solution comprising an agent suitable for rendering exposed surfaces receptive to metal deposition;
contacting the entire surface including said walls and said hydrophobic mask with an accelerator solution comprised of a chelating agent in an alkaline solution for a time period sufficient to selectively remove essentially all of the activator from the hydrophobic mask while accelerating the activator on said walls, the accelerator solution having a pH between about 10 and about 14;
and
depositing a metal layer on the catalyzed surface of said walls.

2 more elements

An improved process for producing a printed circuit on surfaces of an insulating substrate by electroless metal plating, said process including the steps of:

applying a negative, hydrophobic and insulating mask onto a surface of the substrate whereby portions of the surface are unmasked and exposed, the surface of the mask material being resistant to the deposition of a catalytic species capable of catalyzing an electroless metal deposition;
contacting with a catalyst comprising an agent capable of promoting metal deposition, the mask and any unmasked portion of the substrate surface;
contacting the entire surface of the substrate and mask with an accelerator solution;
removing the catalytic species from the surface of the mask;
and
contacting the substrate surface with an electroless metal plating solution to form an electroless metal layer on the unmasked portion of the substrate surface;
the improvement which comprises:
using as the accelerator solution a chelating agent in an alkaline solution having a pH between about 10 and about 14, and contacting the substrate surface with such alkaline accelerator for a time period sufficient to remove essentially all the catalytic species from the surface of the mask and leave catalytic species on the unmasked portion of the substrate surface.

5 more elements

Dependencies are inferred from the claim text.

System for selective metallization of electronic interconnection boards

Life of this patent

System for selective metallization of electronic interconnection boards

Life of this patent

Abstract

Claims21