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

RIGID PRINTED CIRCUIT BOARD WITH INTEGRATED FLEXIBLE BEND AREAS

IP.com Disclosure Number: IPCOM000008017D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2002-May-13
Document File: 2 page(s) / 91K

Publishing Venue

Motorola

Related People

Gary L. Christopher: AUTHOR

Abstract

The electronics industry is constantly striving to stuff more product functions into increasingly smaller packages. One approach to this challenge is "rigid-flex" printed circuit board (pcb) technology. The term rigid-flex sounds like an oxymoron, but it is one used to describe printed circuit boards that have both rigid andflexible sections. This allows a pcb to "fold" on itself, bending at flexible sections while effectively supporting components on its rigid sections. A folding circuit is able to tit into a small- er housing than an all-rigid circuit, Viewed another way, a folding circuit with many functions will tit into the same size housing as a smaller all-rigid cir- cuit with fewer functions.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Page 1 of 2

0 M MO-LA

Technical Developments

RIGID PRINTED CIRCUIT BOARD WITH INTEGRATED FLEXIBLE BEND AREAS

by Gary L. Christopher

  The electronics industry is constantly striving to stuff more product functions into increasingly smaller packages. One approach to this challenge is "rigid-flex" printed circuit board (pcb) technology. The term rigid-flex sounds like an oxymoron, but it is one used to describe printed circuit boards that have both rigid andflexible sections. This allows a pcb to "fold" on itself, bending at flexible sections while effectively supporting components on its rigid sections. A folding circuit is able to tit into a small- er housing than an all-rigid circuit, Viewed another way, a folding circuit with many functions will tit into the same size housing as a smaller all-rigid cir- cuit with fewer functions.

  Rigid-flex circuits have been around for many years. The early types were relatively expensive due to low fabrication yields caused by combining materials (flexible polyimide and rigid epoxy/glass) with very different thermal expansion characteris- tics. This has led to low cost approaches that are fabricated from all epoxy/glass (FR4) or all epoxyiaramid. However, the new approaches

require special construction methods such as pre- punching no-flow prepreg sheets and applying spe- cial solder masks in bend areas. The result is a lim- ited supply base and higher fabrication costs than for standard rigid boards.

  If a conventional rigid pcb could be converted into a rigid-flex pcb with minimal extra processing, the above limitations would be eliminated.

  This concept achieves this by utilizing con- trolled depth routing to "thin" a rigid board to make it flexible in an area that will be bent after assembly. The idea is to re...