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Stacked Die with Vertical Wires for Wearable IC Packages

IP.com Disclosure Number: IPCOM000244836D
Publication Date: 2016-Jan-20
Document File: 5 page(s) / 217K

Publishing Venue

The IP.com Prior Art Database

Abstract

The use of flexible integrated circuit packages for wearable electronic devices is becoming very popular in the industry. There is a high demand in the consumer electronics market segment because of the hype in internet of things (IoT). Companies have been toiling to produce good quality yet flexible integrated circuit packages. These packages must be flexible, bendable and able to withstand high moisture environmental conditions. Some of the electronic products where wearable integrated circuit packages can be found include watches, arm bands, sports shoes, blouses, pants, etc. There is a huge demand by consumers to have wearable electronic gadgets due to the many benefits and conveniences they bring. This market demand will last for years and shape the electronic industry of the future.

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TITLE

Stacked Die with Vertical Wires for Wearable IC Packages

ABSTRACT

The use of flexible integrated circuit packages for wearable electronic devices is becoming very popular in the industry. There is a high demand in the consumer electronics market segment because of the hype in internet of things (IoT).  Companies have been toiling to produce good quality yet flexible integrated circuit packages.  These packages must be flexible, bendable and able to withstand high moisture environmental conditions.  Some of the electronic products where wearable integrated circuit packages can be found include watches, arm bands, sports shoes, blouses, pants, etc.  There is a huge demand by consumers to have wearable electronic gadgets due to the many benefits and conveniences they bring. This market demand will last for years and shape the electronic industry of the future.

CONTENT

Packaging wearable integrated circuits can be a challenge depending on the complexity of the product and the number of dies required.  Packaging cost is also a major concern.  As more dies are put in a package, assembly cost and cycle time increase dramatically.  All these add to the overall cost of the package.  As the functionality of the product grows, people are looking into smarter and cheaper ways to incorporate more dies within a package.

The standard, known method of putting more dies within a single package is to stack them one atop another.  The top die can be smaller, the same or bigger than the bottom die.  In order to stack two dies, typically a spacer (blank die) or something similar like an epoxy with large filler or even a thick die attach film (DAF) must be placed between the dies.  Figures 1 illustrates the standard method of stacking two dies.

Figure 1 Stacking 2 dies with top die smaller, same or larger than the bottom die

We propose an additional method of spacing the stacked dies – by using vertical wires, in order to address the cost concern in stack die packaging.  The most important component towards realizing this die stacking method is the vertical wire itself.  The other component is the silicone encapsulation material that allows the final molded package to be flexible.

The bottom die is bonded to the substrate using standard known die attach methods and materials.  In preparation to bond the top die onto the bottom die, vertical wires are formed on the bond pads of the bottom die.  Wires are also bonded from the bottom die to the substrate.  The top die is then bonded onto the vertical wires.  There is a layer of thin, low cost DAF on the back of the top die to assist in the bonding to the vertical wires.  This follows by wire bonding from the top die to substrate.  Next, the stacked configuration goes for silicone molding or coating, followed by dicing to form individual packages from a molded panel.  Figure 2 illustrates the assembly process steps.

Figure 2 Assembly proc...