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Reliability of press fit contacts and adjoining SMD components on printed circuit boards

 
: Ring, K.; Schreier-Alt, T.

:

Institute of Electrical and Electronics Engineers -IEEE-; IEEE Components, Packaging, and Manufacturing Technology Society:
55th IEEE Holm Conference on Electrical Contacts 2009. Proceedings : 14-16 September 2009, Vancouver, BC, Canada
New York, NY: IEEE, 2009
ISBN: 978-1-4244-3612-5
ISBN: 1-4244-3612-5
ISBN: 978-1-4244-3613-2
pp.225-233
Holm Conference on Electrical Contacts <55, 2009, Vancouver>
English
Conference Paper
Fraunhofer IZM ()
electrical contact; press fit; fiber Bragg grating; strain; SMD

Abstract
Reliability studies of press fit contacts have been performed during environmental stress tests as well as during the manufacturing process. We investigated several press fit pin geometries according to their reliability under thermal, mechanical and electrical load. Correlations with the push-out force have been performed. In this paper we also focus on the mechanical reliability of electronic components which are soldered nearby the press-in pins. During press-in of the contact pin, a strain affected zone is created in the printed circuit board (PCB) near the contacts. The reliability of electronic components soldered near the press fit pins can be reduced if the solder joints are bearing strains > 400 µm/m. We investigated the strains on the surface of PCBs during press fit injection by two different sensor technologies and numerical simulations. Apart from standard electrical strain gauges we used fiber optic Bragg grating sensors. Their advantage is the ability to detect strain gradients, which are common in the sphere of influence of a press fit contact. In a distance of 3 mm away from the investigated contact pins the surface strain on the PCB is around 0.1%; in a distance of 10 mm at least 500 µm/m.

: http://publica.fraunhofer.de/documents/N-107533.html