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Reducing FCMMAP Strip Substrate Warpage and Stiffness by Using a Slot Opening Between Clusters

IP.com Disclosure Number: IPCOM000029156D
Publication Date: 2004-Jun-16
Document File: 3 page(s) / 156K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses a new strip substrate with perpendicular slots running from the longest edges of the strip and between clusters. Benefits include reducing strip warpage and stiffness, and improving the assembly process.

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Reducing FCMMAP Strip Substrate Warpage and Stiffness by Using a Slot Opening Between Clusters

Disclosed is a method that uses a new strip substrate with perpendicular slots running from the longest edges of the strip and between clusters. Benefits include reducing strip warpage and stiffness, and improving the assembly process.

Background

Strip substrate warpage is a major assembly problem. Vacuum suction pressure is reduced on warped and stiffened substrates during the assembly process or the automated handling devices. Also, in many parts of the assembly process, the forces applied on the warped strip substrate can damage the clusters of packages. This produces unreliable packages for customers.

General Description

Currently, the strip substrate of the FCMMAP consists of four clusters of matrixes of molded matrix flip chip packages. The strip design is a simple rectangle (see in Figure 1). The strip substrate undergoes chip attach, capillary underfills (CUF), mold encapsulation, ball attach, and singulation of the cluster into units. Strip substrate warpage is usually caused by a CTE mismatch between substrate die and mold. Typical quarter cluster warpage is shown in Figure 2. This warpage increases with the matrix size or die-to-package ratio of the cluster. In addition to cluster-level warpage, strip-level warpage occurs when the accumulated warpage from one cluster effects to the others by means of the strip substrate border. The strip substrate border acts as a strong...