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CROSS HATCHED PAD DESIGN FOR BONDING EL PANELS TO PCB'S USING Z-AXIS ADHESIVES

IP.com Disclosure Number: IPCOM000006966D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2002-Feb-13
Document File: 1 page(s) / 56K

Publishing Venue

Motorola

Related People

Frank Juskey: AUTHOR [+2]

Abstract

Ditliculties can often be encountered when bondine electroluminescent (EL) panels to PC boards because of the solid gold plane design of the pads. Gold is a noble metal and resists bond formation with almost all substances. Because of gold's inert properties, it is used so that it won't oxidize and cause the EL panel to become intermittent or not light. Many problems have been seen with the current PCB supplier shipping boards with con- taminated bonding pads. The combination of process related contamination and gold's noble bonding proper- ties make it very difficult for the EL panel to be bonded to the board.

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MOTOROLA INC. Technical Developments Volume 19 June 1993

CROSS HATCHED PAD DESIGN FOR BONDING EL PANELS TO PCB'S USING Z-AXIS ADHESIVES

by Frank Juskey and Arnold Hogrefe

Ditliculties can often be encountered when bondine

electroluminescent (EL) panels to PC boards because of the solid gold plane design of the pads. Gold is a noble metal and resists bond formation with almost all substances. Because of gold's inert properties, it is used so that it won't oxidize and cause the EL panel to become intermittent or not light. Many problems have been seen with the current PCB supplier shipping boards with con- taminated bonding pads. The combination of process related contamination and gold's noble bonding proper- ties make it very difficult for the EL panel to be bonded to the board.

  By replacing the. plane design with a cross hatch design made up of a series of parallel and normal 10 mil lines and spaces, portions of the PCB beneath the metalization will be exposed and will allow the forma- tion of a strong bond. A PCB bond pad is defined dur- ing the photolighogmphy step to have a cross hatch design of intersecting lines and spaces typically in a 20 mil pitch. This cross hatching of the pattern will expose the PCB surface below the laminated metal to allow bonding with a z-axis conductive adhesive. It is difhcult to bond to gold, but exposing the organic polymer of the PCB to the organic polymer of the z-axis adhesive will result in a stronger bond.

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Planar Gol...