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Reactive solder material

Reactive solder material description/claims

This is a Divisional Application of Ser. No. 10/141,735 filed May 9, 2002, which is presently pending.

Embodiments described relate to the attachment of devices to a semiconductor die. In particular, embodiments described here relate to thermal management device attachment to a semiconductor die with a solder material.

In the fabrication of microchips or dice, semiconductor wafers are processed and sliced into individual dice. The dice may then be used in a wide variety of devices. For example, a die may be used in an electronic device by being electronically coupled to a printed circuit board (PCB) of the device. However, prior to such an electronic coupling a thermal management device such as an integrated heat spreader (IHS) is often attached to a surface of the die. The IHS may help ensure that any heat within the die is adequately dissipated to prevent damage to the die during operation.

In order to attach a thermal management device to a die, an adhesive is placed at a surface of the die and the device placed atop the adhesive. Adhesives may be of conventional polymers, such as siloxane-based polymers, or other conventional thermally conductive adhesive material.

The ability of an IHS to dissipate heat from the die is dependent in part upon the IHS material selected. Highly efficient heat dissipating materials such as aluminum and copper may be employed. However, the ability of the IHS to dissipate heat from the die is also dependent upon the adhesive which secures the IHS to the die. That is, heat transfer from the die to the IHS is limited by the conductivity of the adhesive between the IHS and the die. Therefore, for example, even where an IHS of a highly efficient heat dissipating material is employed, the effectiveness of the IHS will nevertheless be substantially compromised where the adhesive is of a relatively low conductivity.

In order to more effectively transfer heat, solder materials may be used as a thermal interface. Solder materials, such as indium, are of generally higher conductivity than conventional polymer adhesives. However, solder materials require a metallized surface, flux, and other processing for complete curing and bonding to an otherwise silicon-based non-metal surface. Metallization incurs additional processing time and equipment. Additionally, a conventional solder, such as indium will require the addition of a flux material to clean soldering surface and encourage solder flow. The flux may be delivered by a syringe of yet another piece of equipment. Flux delivery also incurs additional processing time and is required for bonding of conventional solder material to the metallized surface. Solder material is then dispensed above the flux before the heat management device is placed.

While conventional solder materials display better conductivity, they also require a longer and less efficient process than processes already available for use of conventional polymer adhesives. Additional equipment cost and expense associated with reduced throughput is also incurred.

FIG. 1 is a side cross-sectional view of a semiconductor package with a solder preform placed thereon.

FIG. 2 is a perspective view of the semiconductor package of FIG. 1 including a reactive solder material layer.

FIG. 3 is a side cross-sectional view of the semiconductor package of FIG. 2 to accommodate an IHS placed by a pick and place device.

FIG. 4 is a side cross-sectional view of the semiconductor package of FIG. 3 in a reflow apparatus.

FIG. 5 is a perspective view of the semiconductor package of FIG. 4 following reflow.

FIG. 6 is a flow chart summarizing certain embodiments of securing a thermal management device to a semiconductor surface.

• Provisional Patent
• Utility Patent

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