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Improved C4 Reliability Using Low Modulus Dielectric Layer

IP.com Disclosure Number: IPCOM000036956D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 3 page(s) / 65K

Publishing Venue

IBM

Related People

Ellis, TL: AUTHOR [+5]

Abstract

A reduction in controlled collapse chip connector (C4) solder strain can be achieved by using a low modulus dielectric material as a mounting surface for semiconductor chips. Therefore, the C4 reliability can be improved by using a low modulus dielectric material next to the C4. The thermal mismatch between a ceramic carrier and a silicon chip has long been known. The application of a thin layer (1-2 mils) of a low modulus material, e.g., TEFLON*, to a ceramic carrier significant (Image Omitted) ly reduces C4 solder strain, as shown in Fig. 1. The dielectric modulus has a logarithmic relationship to the percentage of solder strain shown by the curve. This curve is drawn from calculated values of solder strain. Plotted in Fig.

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Improved C4 Reliability Using Low Modulus Dielectric Layer

A reduction in controlled collapse chip connector (C4) solder strain can be achieved by using a low modulus dielectric material as a mounting surface for semiconductor chips. Therefore, the C4 reliability can be improved by using a low modulus dielectric material next to the C4. The thermal mismatch between a ceramic carrier and a silicon chip has long been known. The application of a thin layer (1-2 mils) of a low modulus material, e.g., TEFLON*, to a ceramic carrier significant

(Image Omitted)

ly reduces C4 solder strain, as shown in Fig. 1. The dielectric modulus has a logarithmic relationship to the percentage of solder strain shown by the curve. This curve is drawn from calculated values of solder strain. Plotted in Fig. 2 is C4 life test data for three different substrates having approximately the same coefficient of thermal expansion but composed of dielectrics with a wide range of moduli. The materials with lower solder strain predicted in Fig. 1 had improved C4 reliability in Fig. 2. * Trademark of E. I. du Pont de Nemours & Co.

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