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Browse Prior Art Database

FAST EPROM QUARTZ TOPS

IP.com Disclosure Number: IPCOM000008750D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2002-Jul-09
Document File: 3 page(s) / 118K

Publishing Venue

Motorola

Related People

Ken Drake: AUTHOR [+4]

Abstract

EPROM die in a package form which are small enough to fit onto an existing decoder board do not exist. The problem can be resolved in two ways: by creating a low cost quartz top chip carrier package which can be mounted directly on the printed circuit board; and by creating a low cost quartz top pack- age directly on the printed circuit board using a glob-top material.

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MOTOROLA Technical Dev&pn,menis

FAST EPROM QUARTZ TOPS

by Ken Drake, Charles Suter, Therisia Lin and Scott Phillips

  EPROM die in a package form which are small enough to fit onto an existing decoder board do not exist. The problem can be resolved in two ways: by creating a low cost quartz top chip carrier package which can be mounted directly on the printed circuit board; and by creating a low cost quartz top pack- age directly on the printed circuit board using a glob-top material.

  A low cost quartz top chip carrier package, shown in Figure I below, can be created by first die bonding a die to a flat ceramic or glass epoxy substrate and then wire bonding the die to pads on the substrate. A dam formed by an RTV bead is placed around the chip carrier edge area and cured. A second dam is placed atop the first dam to extend

the height of the first dam and then cured. The extended height is required to keep the wire bonds from being crushed by the quartz top when placed on the dam. The bottom side of the quartz glass lid is coated along the edge with the RTV material and is used to seal the quartz glass lid to the dam after the quart glass lid is positioned on the dam and then cured. The finished product is a chip carrier with die that has a quartz glass lid over the EPROM die. The method described above can be used for indi- vidual chip carriers or an entire array of chip carriers. It will also be appreciated that the number of layers of the RTV material does not have to be two when the viscosity of the RTV material is sufficient to maintain the wall height above the wire bonds in a single RTV bead application.

RTV Bead Quartz Glass Lid

Fig. 1

  A low cost quartz top package, shown in Figure 2 on following page, can be created directly on a Printed Circuit Board (PCB) by first die bonding a die directly to the PCB and then wire bonding the die to pads formed on the PCB. A dam formed by an RTV bead is placed around the chip carrier edge area and cured. When a glob top material is used to encapsulate components mounted on the PCB, a dam formed by an RTV bead can be formed around the edge of the PCB at the sam...