Plated Through-Hole Vias in a Porous Polyimide Foil for Flexible Printed Circuit Boards
2008 (English)In: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 18, no 1, 017001- p.Article in journal (Refereed) Published
A fabrication process for high aspect ratio plated through-hole vias is presented for flexibleprinted circuit boards. A 75 μm thick porous Kapton foil that allows direct definition of highaspect ratio through-hole vias by dry photoresist film lithography and electrodeposition ispresented. Pretreatment with swift heavy ion irradiation and wet etching define the poredensity and porosity of the foil, similar to ion-track-etched filter membranes. Thin filmmetallization of a seed layer and lithography of a laminated dry photoresist film define the viasizes and positions. Subsequent through-hole electrodeposition produces vias consisting ofmultiple wires, where each open pore defines one wire. The via geometries are characterizedby scanning electron microscopy. The electrical properties of the vias are characterized byresistance measurements. Vias with an aspect ratio over 2 and a side length of 33 μm showhigh yield with low resistance and low variation in resistance.
Place, publisher, year, edition, pages
2008. Vol. 18, no 1, 017001- p.
IdentifiersURN: urn:nbn:se:uu:diva-96875DOI: 10.1088/0960-1317/18/1/017001ISI: 000252965900030OAI: oai:DiVA.org:uu-96875DiVA: diva2:171603