Browse Prior Art Database

METHOD TO OBTAIN FLAT TOP GLOB CARRIER FOR HIGH SPEED PLACEMENT

IP.com Disclosure Number: IPCOM000006725D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2002-Jan-25
Document File: 2 page(s) / 105K

Publishing Venue

Motorola

Related People

Marc Papageorge: AUTHOR [+3]

Abstract

Coplanar or "dome" shape IC packages using stand- ard epoxy dispensing techniques for chip carriers has always been a concern for placement accuracy. Typical epoxy dispensing has always been directly onto a PC mother board and not a chip carrier due to camber and cost concerns. This technical Motorola Publication will describe a new technique in obtaining "flat top" carriers to provide accurate placement via robot placement cells or chip mounters.

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MOIYWlOLA INC. Technical Developments Volume 17 December 1992

METHOD TO OBTAIN FLAT TOP GLOB CARRIER FOR HIGH SPEED PLACEMENT

by Marc Papageorge, Jerry Pine and Gus Suarez

BACKG,ROUND

  Coplanar or "dome" shape IC packages using stand- ard epoxy dispensing techniques for chip carriers has always been a concern for placement accuracy. Typical epoxy dispensing has always been directly onto a PC mother board and not a chip carrier due to camber and cost concerns. This technical Motorola Publication will describe a new technique in obtaining "flat top" carriers to provide accurate placement via robot placement cells or chip mounters.

DESCRIPTION

  The following critical parameters are needed to obtain a flat top carrier using a molded preform that would be placed within the wirebonded area on top of the wirebonded IC:

1. Die Size
2. Wine loop height
3. Material compatabiity
4. Placement method
5. Cure Profile
6. Preform Shape

  The ideal case for a molded preform would be to use the same material as the dispense or encapsulant material. This would eliminate any thermal or delami- nation concerns. The die size and wirebond area is a concern due to the maximum size of the preform. The preform should be round (preventing stress points) and molded within 10 miIs of the aluminum wire bonding pads. The height of the preform should be greater than 15 mils over the wirebonds (Typical: 30 * 5mil thick- ness) depending on the required thickness of the glob material. The preforms...