Method for circuitizing through-holes by photo-activated seeding

• Main Authors: SIMPSON; CINDY REIDSEMA, VARSIK; JOSEPH EDWARD, SIMPSON; LOGAN LLOYD
• Format: Patent
• Language: English
• Published: 11.07.2000
• Edition: 7
• Subjects: CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METALLURGY; PRINTED CIRCUITS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

A method for selectively metallizing one or more through-holes, other openings (such as slots), or edges of an electronic circuit package comprising the steps of forming a layer of seeding solution on a drilled surface of a substrate of interest exposing this layer to light of appropriate wavelength, through a mask that does not completely cover the through-holes or openings and thereby results in the formation of metal seed on regions of the substrate surface corresponding to the regions of the layer of seeding solution exposed to light; removing the unexposed regions of the layer of seeding solution by subjecting the exposed and unexposed regions of the layer of seeding solution to an alkaline solution. Thereafter, additional metal is deposited, e.g., plated, onto the metal seed using conventional techniques. Significantly, this method does not involve the use of a photoresist, or of a corresponding chemical developer or photoresist stripper. Of additional significance, this method yields plated through-holes or other openings, each of which can accommodate multiple wires, rather then the traditional one wire per through-hole.