Technique produces high resolution cross-sectional radiographs with close interplane spacing for inspecting multilayer boards to be used in providing circuitry routing and module structural support

Arneson, B. E.

Bennett, H. F.

Gregg, P. C.

Hagedorn, R. H.

Kasparas, R.

Moler, R. B.

Pape, R. C.

Riley, D. L.

English

NASA Technical Reports Server

July 197 	 Brief 71-10226 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.. 20546. 
Multilayered Printed Circuit Boards Inspected by X-Ray Laminography 
A new technique called laminography shows con-
siderable promise in producing high-resolution cross-
sectional radiographs, with very close interplane 
spacing, in the inspection of multilayer printed circuit 
Source I 
as 
Sam 
Image PIarP 
R( 
PC 
boards to be used in the dual role of providing 
circuitry routing and module structural support. In such 
applications, the board is normally made of a 
laminate of several elements to depths as great as 
1.27 cm (0.5 in.). 
The inspection of these boards becomes particularly 
important where they are to be subjected to the vibra-
tion and G forces of high altitude and space missions. 
Previously, radiography was a prime method of in-
that, if the sample and image-forming plane rotate 
synchronously, the source-(X-rays)-sample-image 
plane geometry will determine a plane in the sample 
whose image remains fixed in the rotating image-
forming surface. Other planes in the sample will 
result in images which describe epicycles in the image-
forming plane, and, therefore, no sharp image can 
be observed. The relatively uniform smearing of the 
images of planes in the sample is the essential 
mechanism that accounts for the operation of the 
technique. The figure shows a reinforced point and a 
smeared point after 2r rad (360°) rotation. 
A prototype laminograph can inspect any printed 
circuit board to maximum dimensions of 30.48 by 
30.48 by 1.27 cm (12 by 12 by 0.5 in.), and can 
provide three magnifications: 0.2X, LOX, and 4.OX. 
Resolution of the system in this mode is severely 
limited by the television resolution (selected as the 
image-forming medium in the prototype), and only 
gross detail can be observed. At the LOX magni-
fication, reasonable detail is available, but an area 
of only 3.15 by 3.15 cm (1.24 by 1.24 in.) is 
viewed. At the 4.OX magnification, the viewed area 
is only 0.76 by 0.76 cm (0.3 by 0.3 in.), but the 
resolution approaches 0.0025 cm (0.001 in.). This 
small viewed area represents the most serious design 
compromise and was dictated by the resolution 
detail requirement. 
Note: 
The following documentation may be obtained 
spection, but this technique cannot locate deep
	 from: 
flaws in a sample without multiple exposures and a
	 National Technical Information Service 
subsequent careful analysis by personnel with con-
	 Springfield, Virginia 22151 
siderable skill.	 Single document price $3.00 
The laminography technique is based on the fact
	 (or microfiche $0.95) 
-	 (coutintued overle.ti) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United -States	 will be free from privately owned-rights.
https://ntrs.nasa.gov/search.jsp?R=19710000225 2020-03-17T02:19:02+00:00Z
Reference: 
NASACR-98249 (N69-16859), Development 
of a Continuous Scanning Laminograph 
Patent status: 
No patent action is contemplated by NASA. 
Source: R. B. Moler, D. L. Riley; R. C. Pape, 
R. Kasparas, B. E. Arneson, R. H. Hagedorn,
P. C. Gregg and H. F. Bennett of 
I IT Research Institute
under contract to
Marshall Space Flight Center 
(M FS-20849) 
Brief 71-10226	 Category 02


Multilayered printed circuit boards inspected by X-ray laminography

Multilayered printed circuit boards inspected by X-ray laminography

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