A diazo photographic process of clear plastic masters is used in reproducing front and back printed circuit layouts of differing intensity on a single sheet

Perry, J.

English

NASA Technical Reports Server

SECOND EXPOSURE 
Light-Sensitive 
Side of Foil 
Back Layout Master 
Front Layout Master 
Light 04 
Back Layo 
Light-Sensitive 
Side of Foil 
Front Layout Master 
Light
FIRST EXPOSURE 
October 1964	 Brief 63-10596 
NASA TECH BRIEF 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint 
industry with the technical content of an innovation derived from the space program. 
tL	 - ' - 
Front and Back Printed Circuit Layouts Presented on Single Sheet 
i :i 
PRINTED CIRCUIT OVERLAY 
The problem: To reproduce the circuit layouts on 
the front and back of a printed circuit board as over-
lays on one surface of a sheet. Overlay images of the 
two circuits on one sheet would serve as a time-saving 
visual aid to technicians and others concerned with 
the assembly and testing of the electronic modules 
and study of the overall circuitry. 
The solution: A double-exposure method in which 
the front and back circuits are reproduced as images 
of different intensity on a single sheet. A conventional 
diazo process is used for development of the foil on 
which the overlays are imaged.
How it's done: Drawings of the printed circuit 
layouts are made on two sheets of clear plastic mas-
ters, one sheet for the front circuit layout and the 
other for the back circuit layout. Black photographic 
tape and reference markers are used for front-to-back 
registration of the clear plastic masters. A light-sensi-
tive diazo foil is placed between the masters, with the 
sensitive side of the foil facing the master containing 
the front layout. The resulting sandwich is then 
stapled together and placed in a contact copier so that 
the front layout faces a bank of ultraviolet lights. 
After exposure, the sandwich is taken froni the copier 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19630000119 2020-03-11T16:48:05+00:00Z
and the foil is removed and placed behind the two 
masters so that its sensitive side is in direct contact 
with the master containing the back layout. The front-
layout master is registered over the back-layout mas-
ter, which is in contact with the sensitive side of the 
foil. This sandwich is then positioned in the copier, 
with the sensitive side of the film facing the lights, and 
exposed for a prescribed time. After the second ex-
posure, the foil is removed and developed in ammonia 
vapor. 
On the finished print, illustrated above, the darker 
front-circuit layout can easily be distinguished from 
the lighter back-circuit layout. 
Notes: 
1. Although the method described above uses the 
diazo process, other photographic processes can 
also be used. 
2. In lieu of line drawings on clear plastic, the masters 
can consist of diazo transparencies, photographic 
film positives, or drawings on tracing paper.
3. Drawings of electronic components, notes, and 
instructions may be included on the front plastic 
layout or on the mat side of the foil prior to ex-
posure. 
4. This method should have widespread application 
in the preparation of illustrations as teaching aids 
and guides for construction and maintenance of 
complex devices. 
5. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland, 20771 
Reference: B63-10596 
Patent status: NASA encourages commercial use 
of this innovation. No patent action is contemplated. 
Source: J.H. Perry 
(GSFC-93) 
Brief 63-10596


Front and back printed circuit layouts presented on single sheet

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