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Simulation Technique for Determination of Polymer Film Thickness

IP.com Disclosure Number: IPCOM000079772D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Barrett, AJ: AUTHOR [+3]

Abstract

The thickness of a conformal polymer film applied to a hidden area of a ceramic module containing a device chip mounted face down, can be determined by a simulation technique. The ceramic module is replaced by a clear glass substrate 1, having the top surface 2 lapped to simulate the same surface roughness as the ceramic substrate. The approximate Metal pads and corresponding metallurgy configuration 3 is fabricated on the substitute substrate and the device chip is joined in the normal fashion. The encapsulation operation 4 is performed and film thickness determined by viewing the underside of the device, as shown in the drawing at 5.

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Simulation Technique for Determination of Polymer Film Thickness

The thickness of a conformal polymer film applied to a hidden area of a ceramic module containing a device chip mounted face down, can be determined by a simulation technique. The ceramic module is replaced by a clear glass substrate 1, having the top surface 2 lapped to simulate the same surface roughness as the ceramic substrate. The approximate Metal pads and corresponding metallurgy configuration 3 is fabricated on the substitute substrate and the device chip is joined in the normal fashion. The encapsulation operation 4 is performed and film thickness determined by viewing the underside of the device, as shown in the drawing at 5.

With no polymer coating, the finely detailed circuitry on the device chip is obscured by the translucence of the rough glass. As the air/ encapsulant space becomes filled, the view of the device becomes clear. Comparison of a test sample with a set of standards provides the thickness value.

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