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Using Lid with Non-uniform Thickness to Optimize the Flatness and TIM Integrity of Electronic Package

IP.com Disclosure Number: IPCOM000240431D
Publication Date: 2015-Jan-29
Document File: 1 page(s) / 33K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to engineer the cross section of the lid of an electronic package in a way that does not compromise the Thermal Interface Materials (TIM), but keeps the warpage of the package within specification.

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Using Lid with Non-uniform Thickness to Optimize the Flatness and TIM Integrity of Electronic Package

The demand for devices with multi-functionality drives larger die sizes, increased input/output (I/O), and larger laminates. The associated warpage and increased Thermal Interface Materials (TIM) strain impact bond and assembly (BA) yields and package reliability. In prior art, the custom logic chip usually is encapsulated with a one-piece-lid (OPL) of uniform thickness; the package warpage can be improved with increased lid thickness. On the other hand, a more rigid lid exacerbates the stresses in the TIM. To a certain size of chip/laminate, the requirement for package flatness and TIM integrity simultaneously cannot be achieved by using a lid with uniform thickness.

Instead of uniform thickness, the novel solution is to engineer the cross section of the lid in a way that does not rip the TIM, but keeps the warpage of the package within specification. The optimized lid shape for most of the scenario is with less material over the chip, so that it allows the lid to remain compliant with the deformation of chip and thus protect the TIM. In addition, with more material in the peripheral, the package can be stiffened and stay as flat as possible.

Figure: Levels of optimized package flatness and TIM integrity using cavity lid

The Finite Element Method (FEM) of analysis indicates that engineering the cross section of the lid optimizes the packaging solution to keep b...