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Flip chip solder column connection with polymer overcoating

IP.com Disclosure Number: IPCOM000202315D
Publication Date: 2010-Dec-13
Document File: 3 page(s) / 78K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a chip with C4 connections, having polymer encapsulation on the C4 surface, where the polymer is encapsulating the base of the C4 connections, but not the top of the C4 connections. The polymer will efficiently reduce the stress at the base of the C4s.

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Flip chip solder column connection with polymer overcoating

Disclosed is a process for polymer encapsulation of a base of the C4s to mechanically support the base of the C4 connections. More specifically, the disclosed process for encapsulation of a C4 connection can be applied to the bottom side of a 3D chip.

Currently advanced silicon chips often use flip-chip (or C4) connections as input/output contacts to chip carriers. The C4 connections are made of solder, and chip carriers are often made of organic material. Silicon having a coefficient of thermal expansion very different from that of the organic chip carrier typically results in substantial stresses applied to the C4 connection and supporting silicon pad (also called BLM) when the chip is joined to the carrier. In particular chips with low-K dielectric structures, as well as 3D-chips and silicon interposers are sensitive to this stress condition.

The disclosed process of polymer encapsulation of the base of the C4s can be advantageously used to mechanically support the base of the C4 connections. Figure 1 illustrates a general embodiment of this structure. In this example, underfill material is used. More specifically, encapsulation of C4 connection can be applied to the bottom side of a 3D chip.

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Figure 1

Figure 2 depicts a 3D package, having TSVs and C4 connection on the grind side. The bottom side includes oxide and nitride, and polyimide passivation films. The C4 BLM pa...