Browse Prior Art Database

LOW COST BGA ASSEMBLY

IP.com Disclosure Number: IPCOM000009746D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-16
Document File: 2 page(s) / 90K

Publishing Venue

Motorola

Related People

George Carson: AUTHOR [+3]

Abstract

Manufacturing of ball grid array (BGA) packages is composed of many steps and requires a substantial investment in capital equipment and materials. Currently, plastic substrate BGAs are the standard within Motorola. The packages have demonstrated enhanced performance in harsh environmental conditions: liquid-to-liquid thermal shock, air-toair temperature cycling, elevated temperature/high humidity/bias, drop testing, flexure, high tempera~ ture storage, high temperature operating, autoclave, and multiple reflow.

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MOTOROLA

Technical Developments

LOW COST BGA ASSEMBLY

by George Carson, Lillian Thompson and Dan Gamota

Manufacturing of ball grid array (BGA) packages is composed of many steps and requires a substantial investment in capital equipment and materials. Currently, plastic substrate BGAs are the standard within Motorola. The packages have demonstrated enhanced performance in harsh environmental conditions: liquid-to-liquid thermal shock, air-toair temperature cycling, elevated temperature/high humidity/bias, drop testing, flexure, high tempera~ ture storage, high temperature operating, autoclave, and multiple reflow.

The present BGA fabrication process requires several manufacturing steps: die placement and attachment, wire~bonding, a pre-encapsulation bake out step, encapsulation consisting of the dispense of both the glob and the dam materials and associated thermal curing, package logo marking, flux dispense and solder ball attach followed by reflow and flux residue clean. Several robots. engineers, and operators are required for each step. The assembly is per formed in a clean room which further increases the cost for BGA fabrication. Also, the equipment platforms are large and require several different utility connections.

In addition, to the cost associated with the personnel, capital and utilities, material cost represent a large portion of the final cost of the BGA package.

Specifically, the cost of the substrate waste associat~ ed with the panel routing process is substantial; The substrate comprises approximately 60% of the pack~ aging materials cost.

The developed low cost BGA assembly is comprised of a 3-dimensional, monolithic, injectionmolded thermoplastic BGA substrate which incorporates molded through-holes and plastic bumps (Figure 1). A depression is made in the substrate into which a DCA or wire-bondable chip is placed. The geometry of the depression provides a natural dam to conation the encapsu...