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Method for a thermally cured insert connection for substrate-chip interconnection

IP.com Disclosure Number: IPCOM000101672D
Publication Date: 2005-Mar-16
Document File: 3 page(s) / 169K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a thermally cured insert connection for substrate-chip interconnection. Benefits include improved functionality, improved reliability, and improved cost effectiveness.

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Method for a thermally cured insert connection for substrate-chip interconnection

Disclosed is a method for a thermally cured insert connection for substrate-chip interconnection. Benefits include improved functionality, improved reliability, and improved cost effectiveness.

Background

 

      The increasingly smaller form factors of electronic devices require increased input/output (I/O) density. The conventional way to increase that density is to reduce the solder bump pitch and decrease the bump diameter. However,  the smaller diameter increases the risk of poor connections and shorts in the ball attach module. Shorts can occur during reflow when solder balls are close to each other. Opens can occur when the height is low and the bump pitch is fine.

      A conventional solution is a flip-chip molded matrix array package (FCMMAP). Leaded or lead-free solder balls are placed below a thin substrate at a 202 µm bump pitch. Cu columns are placed between the substrate and die to support the die and transfer heat. Convection cooling occurs from the exposed die backside (see Figure 1).

      An alternative solution is to dispense under-fill material in the gap between the die and the substrate. However, pressure between the substrate and chip can be lost due to the previous reflow and result in an epoxy void or delamination (see Figure 2).

General description

      The disclosed method is a thermally cured insert connection for joining a chip and substrate. A solder resist open (SRO) with a copper pad is created on the substrate and painted with a conductive adhesive/paste. A micro-metal column array is created on the surface of the chip and covered with a nonconductive adhesive/film. The chip is aligned to the substrate and the column array is inserted in the via on the substrate. After thermal curing, the conductive adhesive/paste connects the circuit to the chip. The nonconductive adhesive/film adheres the substrate and chip.

      The key elements of the method include:

•             Conductive paste of In2O3/SnO2/Ag with epoxy materials to connect the substrate and chip

•             Column metal insert in paste on the pad

•             Micro-groove around the column to contain the excess conductive paste

•             Paste/adhesive that becomes gel and connects the substrate and die

Advantages

              The disclosed method provides advantages, including:

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