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High Density Probing Using Elastomeric Connectors

IP.com Disclosure Number: IPCOM000102093D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Bradley, SJ: AUTHOR [+2]

Abstract

Disclosed is a method of testing printed circuit boards (PCBs) and flex circuits when the necessary connections to be made are very close together, employing a mirror image flex circuit with fan-out and a layer of anisotropically conductive elastomer placed between the test flex circuit and the mirror flex circuit.

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This is the abbreviated version, containing approximately 63% of the total text.

High Density Probing Using Elastomeric Connectors

       Disclosed is a method of testing printed circuit boards
(PCBs) and flex circuits when the necessary connections to be made
are very close together, employing a mirror image flex circuit with
fan-out and a layer of anisotropically conductive elastomer placed
between the test flex circuit and the mirror flex circuit.

      Conventional testing of PCBs and flex circuits uses a
mechanical device with pins that are brought into contact with
component mounting pads.  Connections from the pins then lead off to
external test equipment. This approach suffers from the fact that the
test rig of pins is expensive to make and it is difficult to position
the pins correctly, especially when the mounting pads are very close
together.

      An improved method using two flex circuits and an intervening
anisotropic elastomer layer is illustrated in Figs. 1 and 2.  A flex
circuit 1 has several components 2 mounted on it.  Each component is
attached via a set of pads 3 to the conducting tracks 4 on the flex
circuit.  The operation of component 5 can be tested using an
anisotropic layer of an elastomer 20, such as metal/silicone rubber
laminate, and a second flex circuit 11.  The elastomeric layer
conducts only in the direction of arrow A, i.e., from flex circuit 1
to flex circuit 11, and so does not short out pads 3.  The positions
of pads 13 on the underside of flex circuit 11 are a mirror image of
the positions of p...