Browse Prior Art Database

Dimensionally Controlled Semiconductor Package

IP.com Disclosure Number: IPCOM000041499D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Booth, RB: AUTHOR [+2]

Abstract

In order to obtain efficient heat dissipation in a semiconductor package using a thermal compound to convey heat from the chip to the heat sink, it is imperative that the gap between the chip and the heat sink, which is filled with a thermal compound, be controlled within a very close tolerance. The thickness of the seal between the cap and substrate exerts a profound influence on the thickness of this gap. The thickness dimension of the seal is relatively hard to hold within required tolerances. In this process a lead-tin alloy preform 10 is fabricated to facilitate hermetic sealing of the cap. In the four corners of the preform 10 are located copper disks 12 during manufacture of the preform.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 83% of the total text.

Page 1 of 2

Dimensionally Controlled Semiconductor Package

In order to obtain efficient heat dissipation in a semiconductor package using a thermal compound to convey heat from the chip to the heat sink, it is imperative that the gap between the chip and the heat sink, which is filled with a thermal compound, be controlled within a very close tolerance. The thickness of the seal between the cap and substrate exerts a profound influence on the thickness of this gap. The thickness dimension of the seal is relatively hard to hold within required tolerances. In this process a lead-tin alloy preform 10 is fabricated to facilitate hermetic sealing of the cap. In the four corners of the preform 10 are located copper disks 12 during manufacture of the preform. In placing the cap 14 on substrate 16 provided with a refractory metal and solderable overlayer metal 18, the preform 10 is placed on the substrate and heated. The heating of the assembly attaches the preform including the copper disk to the substrate seal band 18. The resultant preform is then subjected to a flattening operation, and the cap 14 placed in position. Preferably, the cap is preloaded and placed in an inert atmosphere conveyor furnace with a suitable temperature profile to join the cap to the substrate. By controlling the thickness of the solder seal between the substrate 16 and cap 14, the overall dimension between the inner top surface of cap 14 and the top surface of substrate 16 is controlled. Since the distan...