Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Double Exposure of Photo-Sensitive Insulator for Pin-Hole Elimination

IP.com Disclosure Number: IPCOM000111170D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Shirai, M: AUTHOR [+2]

Abstract

Disclosed is an exposure method for reducing defects of PCB (Printed Circuit Board) with photo via holes formed by a negative-type photo-sensitive dielectric. For negative type photo-sensitive dielectric, contamination at exposed regions causes defects such as pin-holes. Such defects can be solved by double exposure with different masks.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 90% of the total text.

Double Exposure of Photo-Sensitive Insulator for Pin-Hole Elimination

      Disclosed is an exposure method for reducing defects of PCB
(Printed Circuit Board) with photo via holes formed by a
negative-type photo-sensitive dielectric.  For negative type
photo-sensitive dielectric, contamination at exposed regions causes
defects such as pin-holes.  Such defects can be solved by double
exposure with different masks.

      In a photo process in which a negative-type photo-sensitive
insulator is used to define vias, contamination on the mask, mask
cover film or other parts which lie in the light path results in the
formation of pin-holes in the insulator.  These pin-holes become
serious defects from the point of reliability and electrical
performance.

      The defects caused by such contamination can be eliminated by
double exposure which comprises a first step for exposing the
insulator with a normal mask with original via size and a second step
for exposing the insulator with the mask with larger via size.  The
order of these two masks being used can be reversed.

      The probability that different contaminations hit the same
location is negligible and thus the pin-holes can be eliminated
effectively by exposing the insulator twice with the different masks.

      The reason why the two masks should have different via sizes is
from the tolerance of mask positioning.  The second mask has to have
larger via size to maintain the via size formed by t...