Browse Prior Art Database

Multilayer Coding

IP.com Disclosure Number: IPCOM000105498D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Effenberger, H: AUTHOR [+3]

Abstract

Described is a method of coding flat objects, in particular circuit boards, which are subject to different etch and deposition steps, and of retaining such coding during the production process and surface changes occurring therein. The invention is also suitable for semiconductor wafers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 83% of the total text.

Multilayer Coding

      Described is a method of coding flat objects, in particular
circuit boards, which are subject to different etch and deposition
steps, and of retaining such coding during the production process and
surface changes occurring therein.  The invention is also suitable
for semiconductor wafers.

      Previously described is the use of a bar code for marking
circuit boards which is retained as an opening along the edge of the
circuit board during the production process and read by an optical
reader sending a light beam through the opening .[*]  This eliminates
the disadvantages of circuit boards with ink markings which would be
removed during subsequent process steps and contaminate the bath used
for treatment.

      The proposed improvement uses an ink jet to inscribe the
photo-resist protective foil (with a bar code or characters) in the
form of a photomask, thus identifying the individual inner layers of
circuit boards during their production.  In the subsequent etch step,
this marking is transferred to the copper foil and retained during
the entire production process.  It is automatically read, for
example, by a CCD matrix camera and an infrared LED light source and
decoded by image data processing.

      During the assembly of the circuit board consisting of several
inner layers, the markings of the individual layers are read and
converted into an identification for the entire board.  Upon
completion of assembly, the markings of...