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Copper Less Carrier Package

IP.com Disclosure Number: IPCOM000248050D
Publication Date: 2016-Oct-21
Document File: 6 page(s) / 492K

Publishing Venue

The IP.com Prior Art Database

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Page 01 of 6

Copper Less Carrier Package

Background

This invention discloses the integration of Copper Less Carrier package, which is entirely new by utilising encapsulant as carrier or dielectric without the Cu or metal routing designs.

It is a low cost driven concept simply achievable in assembly house given the mold chase design and laser ablation capability. Having said that, the protrusion pattern is designed on the mold chase, this created the cavities or grooves on a mold strip carrier corresponding to the protrusions in the mold cast formation. Alternatively, the cavities can be created by means of laser groove technology on the flat mold carrier, instead of pre-formed by mold chase. Each cavity is dictating the placement location for the solder ball or solder paste, which is either directly placed on it or opposite of it on the reverse side. The top surface of deformed solder ball on the mold carrier enacts as wire bond pad, whereas the bottom surface of solder ball enacts as ball pad or terminal pad, which requires exposure through bottom strip grinding or laser ablation. The Copper Less Carrier package featured with or without stand-off is depending on the design requirements or thickness of the mold strip carrier. The conceptualized features and process methodologies are further illustrated in the next section.

Figure 1A: Copper Less Carrier Package without solder ball stand-off

Description

In the first embodiment, a mold strip carrier with cavities or grooves is created by using the mold chase design or laser groove pattern. The cavity prints on top of strip are the pockets for solder ball placements which are homogenous in squarish or rectangular shape, and uniform in dimensions as represented in Figure 2A. The process to fill the squarish or rectangular cavities with solder balls as shown in Figure 2B can be done either by fluxing followed by solder ball attach, or through the solder paste printing method using stencil. The solder ball size would determine the flatness of deformed solder ball surface in the cavity, whereby the solder ball would fuse and fill up the cavity during reflow process in Figure 2C. The flatness of deformed solder ball surface is critical since its top surface is the landing area for wire connections. After reflow as given in Figure 2D, the IC chips are placed onto the mold


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Copper Less Carrier Package

surface of the mold strip carrier using the die adhesive or epoxy through the die attach process, followed by the wire bonding process to connect wires between the conductive solder pads and bond pads on IC chip. Next, the bonded strip is subjected to molding process as shown in Figure 2E using the encapsulant type based on package requirements, which is denoted as encapsulant 2. On the reverse side of the strip in Figure 2F, the pit holes or terminal pad recesses are created corresponding to respective location of deformed solder balls, whereby the bottom of solder balls or terminal pads are...